make update-server-info more robust
[gitweb.git] / diff.c
diff --git a/diff.c b/diff.c
index 0ecbf325a264f3829922017e46451009a332d0ef..867f034b8ffc052d28f28a86fd9f52a5aa5b2c82 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -15,6 +15,8 @@
 #include "sigchain.h"
 #include "submodule.h"
 #include "ll-merge.h"
+#include "string-list.h"
+#include "argv-array.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
 #endif
 
 static int diff_detect_rename_default;
-static int diff_rename_limit_default = 200;
+static int diff_rename_limit_default = 400;
 static int diff_suppress_blank_empty;
-int diff_use_color_default = -1;
+static int diff_use_color_default = -1;
+static int diff_context_default = 3;
 static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
+static const char *diff_order_file_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
+static int diff_stat_graph_width;
+static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
+static long diff_algorithm;
 
 static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
@@ -45,27 +52,91 @@ static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_NORMAL,       /* FUNCINFO */
 };
 
-static int parse_diff_color_slot(const char *var, int ofs)
+static int parse_diff_color_slot(const char *var)
 {
-       if (!strcasecmp(var+ofs, "plain"))
+       if (!strcasecmp(var, "plain"))
                return DIFF_PLAIN;
-       if (!strcasecmp(var+ofs, "meta"))
+       if (!strcasecmp(var, "meta"))
                return DIFF_METAINFO;
-       if (!strcasecmp(var+ofs, "frag"))
+       if (!strcasecmp(var, "frag"))
                return DIFF_FRAGINFO;
-       if (!strcasecmp(var+ofs, "old"))
+       if (!strcasecmp(var, "old"))
                return DIFF_FILE_OLD;
-       if (!strcasecmp(var+ofs, "new"))
+       if (!strcasecmp(var, "new"))
                return DIFF_FILE_NEW;
-       if (!strcasecmp(var+ofs, "commit"))
+       if (!strcasecmp(var, "commit"))
                return DIFF_COMMIT;
-       if (!strcasecmp(var+ofs, "whitespace"))
+       if (!strcasecmp(var, "whitespace"))
                return DIFF_WHITESPACE;
-       if (!strcasecmp(var+ofs, "func"))
+       if (!strcasecmp(var, "func"))
                return DIFF_FUNCINFO;
        return -1;
 }
 
+static int parse_dirstat_params(struct diff_options *options, const char *params_string,
+                               struct strbuf *errmsg)
+{
+       char *params_copy = xstrdup(params_string);
+       struct string_list params = STRING_LIST_INIT_NODUP;
+       int ret = 0;
+       int i;
+
+       if (*params_copy)
+               string_list_split_in_place(&params, params_copy, ',', -1);
+       for (i = 0; i < params.nr; i++) {
+               const char *p = params.items[i].string;
+               if (!strcmp(p, "changes")) {
+                       DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
+                       DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
+               } else if (!strcmp(p, "lines")) {
+                       DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
+                       DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
+               } else if (!strcmp(p, "files")) {
+                       DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
+                       DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
+               } else if (!strcmp(p, "noncumulative")) {
+                       DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
+               } else if (!strcmp(p, "cumulative")) {
+                       DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
+               } else if (isdigit(*p)) {
+                       char *end;
+                       int permille = strtoul(p, &end, 10) * 10;
+                       if (*end == '.' && isdigit(*++end)) {
+                               /* only use first digit */
+                               permille += *end - '0';
+                               /* .. and ignore any further digits */
+                               while (isdigit(*++end))
+                                       ; /* nothing */
+                       }
+                       if (!*end)
+                               options->dirstat_permille = permille;
+                       else {
+                               strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
+                                           p);
+                               ret++;
+                       }
+               } else {
+                       strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
+                       ret++;
+               }
+
+       }
+       string_list_clear(&params, 0);
+       free(params_copy);
+       return ret;
+}
+
+static int parse_submodule_params(struct diff_options *options, const char *value)
+{
+       if (!strcmp(value, "log"))
+               DIFF_OPT_SET(options, SUBMODULE_LOG);
+       else if (!strcmp(value, "short"))
+               DIFF_OPT_CLR(options, SUBMODULE_LOG);
+       else
+               return -1;
+       return 0;
+}
+
 static int git_config_rename(const char *var, const char *value)
 {
        if (!value)
@@ -75,6 +146,21 @@ static int git_config_rename(const char *var, const char *value)
        return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
 }
 
+long parse_algorithm_value(const char *value)
+{
+       if (!value)
+               return -1;
+       else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
+               return 0;
+       else if (!strcasecmp(value, "minimal"))
+               return XDF_NEED_MINIMAL;
+       else if (!strcasecmp(value, "patience"))
+               return XDF_PATIENCE_DIFF;
+       else if (!strcasecmp(value, "histogram"))
+               return XDF_HISTOGRAM_DIFF;
+       return -1;
+}
+
 /*
  * These are to give UI layer defaults.
  * The core-level commands such as git-diff-files should
@@ -84,7 +170,13 @@ static int git_config_rename(const char *var, const char *value)
 int git_diff_ui_config(const char *var, const char *value, void *cb)
 {
        if (!strcmp(var, "diff.color") || !strcmp(var, "color.diff")) {
-               diff_use_color_default = git_config_colorbool(var, value, -1);
+               diff_use_color_default = git_config_colorbool(var, value);
+               return 0;
+       }
+       if (!strcmp(var, "diff.context")) {
+               diff_context_default = git_config_int(var, value);
+               if (diff_context_default < 0)
+                       return -1;
                return 0;
        }
        if (!strcmp(var, "diff.renames")) {
@@ -103,32 +195,55 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
                diff_no_prefix = git_config_bool(var, value);
                return 0;
        }
+       if (!strcmp(var, "diff.statgraphwidth")) {
+               diff_stat_graph_width = git_config_int(var, value);
+               return 0;
+       }
        if (!strcmp(var, "diff.external"))
                return git_config_string(&external_diff_cmd_cfg, var, value);
        if (!strcmp(var, "diff.wordregex"))
                return git_config_string(&diff_word_regex_cfg, var, value);
+       if (!strcmp(var, "diff.orderfile"))
+               return git_config_pathname(&diff_order_file_cfg, var, value);
 
        if (!strcmp(var, "diff.ignoresubmodules"))
                handle_ignore_submodules_arg(&default_diff_options, value);
 
+       if (!strcmp(var, "diff.submodule")) {
+               if (parse_submodule_params(&default_diff_options, value))
+                       warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
+                               value);
+               return 0;
+       }
+
+       if (!strcmp(var, "diff.algorithm")) {
+               diff_algorithm = parse_algorithm_value(value);
+               if (diff_algorithm < 0)
+                       return -1;
+               return 0;
+       }
+
+       if (git_color_config(var, value, cb) < 0)
+               return -1;
+
        return git_diff_basic_config(var, value, cb);
 }
 
 int git_diff_basic_config(const char *var, const char *value, void *cb)
 {
+       const char *name;
+
        if (!strcmp(var, "diff.renamelimit")) {
                diff_rename_limit_default = git_config_int(var, value);
                return 0;
        }
 
-       switch (userdiff_config(var, value)) {
-               case 0: break;
-               case -1: return -1;
-               default: return 0;
-       }
+       if (userdiff_config(var, value) < 0)
+               return -1;
 
-       if (!prefixcmp(var, "diff.color.") || !prefixcmp(var, "color.diff.")) {
-               int slot = parse_diff_color_slot(var, 11);
+       if (skip_prefix(var, "diff.color.", &name) ||
+           skip_prefix(var, "color.diff.", &name)) {
+               int slot = parse_diff_color_slot(name);
                if (slot < 0)
                        return 0;
                if (!value)
@@ -145,10 +260,21 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
                return 0;
        }
 
-       if (!prefixcmp(var, "submodule."))
+       if (!strcmp(var, "diff.dirstat")) {
+               struct strbuf errmsg = STRBUF_INIT;
+               default_diff_options.dirstat_permille = diff_dirstat_permille_default;
+               if (parse_dirstat_params(&default_diff_options, value, &errmsg))
+                       warning(_("Found errors in 'diff.dirstat' config variable:\n%s"),
+                               errmsg.buf);
+               strbuf_release(&errmsg);
+               diff_dirstat_permille_default = default_diff_options.dirstat_permille;
+               return 0;
+       }
+
+       if (starts_with(var, "submodule."))
                return parse_submodule_config_option(var, value);
 
-       return git_color_default_config(var, value, cb);
+       return git_default_config(var, value, cb);
 }
 
 static char *quote_two(const char *one, const char *two)
@@ -245,6 +371,15 @@ static int fill_mmfile(mmfile_t *mf, struct diff_filespec *one)
        return 0;
 }
 
+/* like fill_mmfile, but only for size, so we can avoid retrieving blob */
+static unsigned long diff_filespec_size(struct diff_filespec *one)
+{
+       if (!DIFF_FILE_VALID(one))
+               return 0;
+       diff_populate_filespec(one, 1);
+       return one->size;
+}
+
 static int count_trailing_blank(mmfile_t *mf, unsigned ws_rule)
 {
        char *ptr = mf->ptr;
@@ -297,12 +432,7 @@ static void emit_line_0(struct diff_options *o, const char *set, const char *res
        int nofirst;
        FILE *file = o->file;
 
-       if (o->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = o->output_prefix(o, o->output_prefix_data);
-               assert(msg);
-               fwrite(msg->buf, msg->len, 1, file);
-       }
+       fputs(diff_line_prefix(o), file);
 
        if (len == 0) {
                has_trailing_newline = (first == '\n');
@@ -395,9 +525,9 @@ static void emit_hunk_header(struct emit_callback *ecbdata,
        ep += 2; /* skip over @@ */
 
        /* The hunk header in fraginfo color */
-       strbuf_add(&msgbuf, frag, strlen(frag));
+       strbuf_addstr(&msgbuf, frag);
        strbuf_add(&msgbuf, line, ep - line);
-       strbuf_add(&msgbuf, reset, strlen(reset));
+       strbuf_addstr(&msgbuf, reset);
 
        /*
         * trailing "\r\n"
@@ -411,15 +541,15 @@ static void emit_hunk_header(struct emit_callback *ecbdata,
                if (*ep != ' ' && *ep != '\t')
                        break;
        if (ep != cp) {
-               strbuf_add(&msgbuf, plain, strlen(plain));
+               strbuf_addstr(&msgbuf, plain);
                strbuf_add(&msgbuf, cp, ep - cp);
-               strbuf_add(&msgbuf, reset, strlen(reset));
+               strbuf_addstr(&msgbuf, reset);
        }
 
        if (ep < line + len) {
-               strbuf_add(&msgbuf, func, strlen(func));
+               strbuf_addstr(&msgbuf, func);
                strbuf_add(&msgbuf, ep, line + len - ep);
-               strbuf_add(&msgbuf, reset, strlen(reset));
+               strbuf_addstr(&msgbuf, reset);
        }
 
        strbuf_add(&msgbuf, line + len, org_len - len);
@@ -496,6 +626,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
        if (!endp) {
                const char *plain = diff_get_color(ecb->color_diff,
                                                   DIFF_PLAIN);
+               putc('\n', ecb->opt->file);
                emit_line_0(ecb->opt, plain, reset, '\\',
                            nneof, strlen(nneof));
        }
@@ -510,23 +641,16 @@ static void emit_rewrite_diff(const char *name_a,
                              struct diff_options *o)
 {
        int lc_a, lc_b;
-       int color_diff = DIFF_OPT_TST(o, COLOR_DIFF);
        const char *name_a_tab, *name_b_tab;
-       const char *metainfo = diff_get_color(color_diff, DIFF_METAINFO);
-       const char *fraginfo = diff_get_color(color_diff, DIFF_FRAGINFO);
-       const char *reset = diff_get_color(color_diff, DIFF_RESET);
+       const char *metainfo = diff_get_color(o->use_color, DIFF_METAINFO);
+       const char *fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
+       const char *reset = diff_get_color(o->use_color, DIFF_RESET);
        static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
        const char *a_prefix, *b_prefix;
        char *data_one, *data_two;
        size_t size_one, size_two;
        struct emit_callback ecbdata;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
-
-       if (o && o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
                a_prefix = o->b_prefix;
@@ -550,9 +674,9 @@ static void emit_rewrite_diff(const char *name_a,
        size_two = fill_textconv(textconv_two, two, &data_two);
 
        memset(&ecbdata, 0, sizeof(ecbdata));
-       ecbdata.color_diff = color_diff;
+       ecbdata.color_diff = want_color(o->use_color);
        ecbdata.found_changesp = &o->found_changes;
-       ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
+       ecbdata.ws_rule = whitespace_rule(name_b);
        ecbdata.opt = o;
        if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
                mmfile_t mf1, mf2;
@@ -572,11 +696,14 @@ static void emit_rewrite_diff(const char *name_a,
                line_prefix, metainfo, a_name.buf, name_a_tab, reset,
                line_prefix, metainfo, b_name.buf, name_b_tab, reset,
                line_prefix, fraginfo);
-       print_line_count(o->file, lc_a);
+       if (!o->irreversible_delete)
+               print_line_count(o->file, lc_a);
+       else
+               fprintf(o->file, "?,?");
        fprintf(o->file, " +");
        print_line_count(o->file, lc_b);
        fprintf(o->file, " @@%s\n", reset);
-       if (lc_a)
+       if (lc_a && !o->irreversible_delete)
                emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
        if (lc_b)
                emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
@@ -606,22 +733,20 @@ static void diff_words_append(char *line, unsigned long len,
        buffer->text.ptr[buffer->text.size] = '\0';
 }
 
-struct diff_words_style_elem
-{
+struct diff_words_style_elem {
        const char *prefix;
        const char *suffix;
        const char *color; /* NULL; filled in by the setup code if
                            * color is enabled */
 };
 
-struct diff_words_style
-{
+struct diff_words_style {
        enum diff_words_type type;
        struct diff_words_style_elem new, old, ctx;
        const char *newline;
 };
 
-struct diff_words_style diff_words_styles[] = {
+static struct diff_words_style diff_words_styles[] = {
        { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
        { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
        { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
@@ -721,18 +846,14 @@ static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
        int minus_first, minus_len, plus_first, plus_len;
        const char *minus_begin, *minus_end, *plus_begin, *plus_end;
        struct diff_options *opt = diff_words->opt;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix;
 
        if (line[0] != '@' || parse_hunk_header(line, len,
                        &minus_first, &minus_len, &plus_first, &plus_len))
                return;
 
        assert(opt);
-       if (opt->output_prefix) {
-               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(opt);
 
        /* POSIX requires that first be decremented by one if len == 0... */
        if (minus_len) {
@@ -856,14 +977,10 @@ static void diff_words_show(struct diff_words_data *diff_words)
        struct diff_words_style *style = diff_words->style;
 
        struct diff_options *opt = diff_words->opt;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix;
 
        assert(opt);
-       if (opt->output_prefix) {
-               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(opt);
 
        /* special case: only removal */
        if (!diff_words->plus.text.size) {
@@ -911,10 +1028,74 @@ static void diff_words_flush(struct emit_callback *ecbdata)
                diff_words_show(ecbdata->diff_words);
 }
 
+static void diff_filespec_load_driver(struct diff_filespec *one)
+{
+       /* Use already-loaded driver */
+       if (one->driver)
+               return;
+
+       if (S_ISREG(one->mode))
+               one->driver = userdiff_find_by_path(one->path);
+
+       /* Fallback to default settings */
+       if (!one->driver)
+               one->driver = userdiff_find_by_name("default");
+}
+
+static const char *userdiff_word_regex(struct diff_filespec *one)
+{
+       diff_filespec_load_driver(one);
+       return one->driver->word_regex;
+}
+
+static void init_diff_words_data(struct emit_callback *ecbdata,
+                                struct diff_options *orig_opts,
+                                struct diff_filespec *one,
+                                struct diff_filespec *two)
+{
+       int i;
+       struct diff_options *o = xmalloc(sizeof(struct diff_options));
+       memcpy(o, orig_opts, sizeof(struct diff_options));
+
+       ecbdata->diff_words =
+               xcalloc(1, sizeof(struct diff_words_data));
+       ecbdata->diff_words->type = o->word_diff;
+       ecbdata->diff_words->opt = o;
+       if (!o->word_regex)
+               o->word_regex = userdiff_word_regex(one);
+       if (!o->word_regex)
+               o->word_regex = userdiff_word_regex(two);
+       if (!o->word_regex)
+               o->word_regex = diff_word_regex_cfg;
+       if (o->word_regex) {
+               ecbdata->diff_words->word_regex = (regex_t *)
+                       xmalloc(sizeof(regex_t));
+               if (regcomp(ecbdata->diff_words->word_regex,
+                           o->word_regex,
+                           REG_EXTENDED | REG_NEWLINE))
+                       die ("Invalid regular expression: %s",
+                            o->word_regex);
+       }
+       for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
+               if (o->word_diff == diff_words_styles[i].type) {
+                       ecbdata->diff_words->style =
+                               &diff_words_styles[i];
+                       break;
+               }
+       }
+       if (want_color(o->use_color)) {
+               struct diff_words_style *st = ecbdata->diff_words->style;
+               st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
+               st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
+               st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
+       }
+}
+
 static void free_diff_words_data(struct emit_callback *ecbdata)
 {
        if (ecbdata->diff_words) {
                diff_words_flush(ecbdata);
+               free (ecbdata->diff_words->opt);
                free (ecbdata->diff_words->minus.text.ptr);
                free (ecbdata->diff_words->minus.orig);
                free (ecbdata->diff_words->plus.text.ptr);
@@ -930,11 +1111,21 @@ static void free_diff_words_data(struct emit_callback *ecbdata)
 
 const char *diff_get_color(int diff_use_color, enum color_diff ix)
 {
-       if (diff_use_color)
+       if (want_color(diff_use_color))
                return diff_colors[ix];
        return "";
 }
 
+const char *diff_line_prefix(struct diff_options *opt)
+{
+       struct strbuf *msgbuf;
+       if (!opt->output_prefix)
+               return "";
+
+       msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+       return msgbuf->buf;
+}
+
 static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
 {
        const char *cp;
@@ -975,13 +1166,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
        struct diff_options *o = ecbdata->opt;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
-
-       if (o && o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (ecbdata->header) {
                fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
@@ -1037,14 +1222,31 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                        diff_words_append(line, len,
                                          &ecbdata->diff_words->plus);
                        return;
+               } else if (starts_with(line, "\\ ")) {
+                       /*
+                        * Eat the "no newline at eof" marker as if we
+                        * saw a "+" or "-" line with nothing on it,
+                        * and return without diff_words_flush() to
+                        * defer processing. If this is the end of
+                        * preimage, more "+" lines may come after it.
+                        */
+                       return;
                }
                diff_words_flush(ecbdata);
                if (ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN) {
                        emit_line(ecbdata->opt, plain, reset, line, len);
                        fputs("~\n", ecbdata->opt->file);
                } else {
-                       /* don't print the prefix character */
-                       emit_line(ecbdata->opt, plain, reset, line+1, len-1);
+                       /*
+                        * Skip the prefix character, if any.  With
+                        * diff_suppress_blank_empty, there may be
+                        * none.
+                        */
+                       if (line[0] != '\n') {
+                             line++;
+                             len--;
+                       }
+                       emit_line(ecbdata->opt, plain, reset, line, len);
                }
                return;
        }
@@ -1069,6 +1271,7 @@ static char *pprint_rename(const char *a, const char *b)
        const char *new = b;
        struct strbuf name = STRBUF_INIT;
        int pfx_length, sfx_length;
+       int pfx_adjust_for_slash;
        int len_a = strlen(a);
        int len_b = strlen(b);
        int a_midlen, b_midlen;
@@ -1095,7 +1298,18 @@ static char *pprint_rename(const char *a, const char *b)
        old = a + len_a;
        new = b + len_b;
        sfx_length = 0;
-       while (a <= old && b <= new && *old == *new) {
+       /*
+        * If there is a common prefix, it must end in a slash.  In
+        * that case we let this loop run 1 into the prefix to see the
+        * same slash.
+        *
+        * If there is no common prefix, we cannot do this as it would
+        * underrun the input strings.
+        */
+       pfx_adjust_for_slash = (pfx_length ? 1 : 0);
+       while (a + pfx_length - pfx_adjust_for_slash <= old &&
+              b + pfx_length - pfx_adjust_for_slash <= new &&
+              *old == *new) {
                if (*old == '/')
                        sfx_length = len_a - (old - a);
                old--;
@@ -1140,6 +1354,7 @@ struct diffstat_t {
                unsigned is_unmerged:1;
                unsigned is_binary:1;
                unsigned is_renamed:1;
+               unsigned is_interesting:1;
                uintmax_t added, deleted;
        } **files;
 };
@@ -1149,12 +1364,8 @@ static struct diffstat_file *diffstat_add(struct diffstat_t *diffstat,
                                          const char *name_b)
 {
        struct diffstat_file *x;
-       x = xcalloc(sizeof (*x), 1);
-       if (diffstat->nr == diffstat->alloc) {
-               diffstat->alloc = alloc_nr(diffstat->alloc);
-               diffstat->files = xrealloc(diffstat->files,
-                               diffstat->alloc * sizeof(x));
-       }
+       x = xcalloc(1, sizeof(*x));
+       ALLOC_GROW(diffstat->files, diffstat->nr + 1, diffstat->alloc);
        diffstat->files[diffstat->nr++] = x;
        if (name_b) {
                x->from_name = xstrdup(name_a);
@@ -1183,13 +1394,15 @@ const char mime_boundary_leader[] = "------------";
 
 static int scale_linear(int it, int width, int max_change)
 {
+       if (!it)
+               return 0;
        /*
-        * make sure that at least one '-' is printed if there were deletions,
-        * and likewise for '+'.
+        * make sure that at least one '-' or '+' is printed if
+        * there is any change to this path. The easiest way is to
+        * scale linearly as if the alloted width is one column shorter
+        * than it is, and then add 1 to the result.
         */
-       if (max_change < 2)
-               return it;
-       return ((it - 1) * (width - 1) + max_change - 1) / (max_change - 1);
+       return 1 + (it * (width - 1) / max_change);
 }
 
 static void show_name(FILE *file,
@@ -1229,77 +1442,196 @@ static void fill_print_name(struct diffstat_file *file)
        file->print_name = pname;
 }
 
+int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
+{
+       struct strbuf sb = STRBUF_INIT;
+       int ret;
+
+       if (!files) {
+               assert(insertions == 0 && deletions == 0);
+               return fprintf(fp, "%s\n", " 0 files changed");
+       }
+
+       strbuf_addf(&sb,
+                   (files == 1) ? " %d file changed" : " %d files changed",
+                   files);
+
+       /*
+        * For binary diff, the caller may want to print "x files
+        * changed" with insertions == 0 && deletions == 0.
+        *
+        * Not omitting "0 insertions(+), 0 deletions(-)" in this case
+        * is probably less confusing (i.e skip over "2 files changed
+        * but nothing about added/removed lines? Is this a bug in Git?").
+        */
+       if (insertions || deletions == 0) {
+               strbuf_addf(&sb,
+                           (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
+                           insertions);
+       }
+
+       if (deletions || insertions == 0) {
+               strbuf_addf(&sb,
+                           (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
+                           deletions);
+       }
+       strbuf_addch(&sb, '\n');
+       ret = fputs(sb.buf, fp);
+       strbuf_release(&sb);
+       return ret;
+}
+
 static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
        int i, len, add, del, adds = 0, dels = 0;
        uintmax_t max_change = 0, max_len = 0;
-       int total_files = data->nr;
-       int width, name_width;
-       const char *reset, *set, *add_c, *del_c;
+       int total_files = data->nr, count;
+       int width, name_width, graph_width, number_width = 0, bin_width = 0;
+       const char *reset, *add_c, *del_c;
        const char *line_prefix = "";
-       struct strbuf *msg = NULL;
+       int extra_shown = 0;
 
        if (data->nr == 0)
                return;
 
-       if (options->output_prefix) {
-               msg = options->output_prefix(options, options->output_prefix_data);
-               line_prefix = msg->buf;
-       }
-
-       width = options->stat_width ? options->stat_width : 80;
-       name_width = options->stat_name_width ? options->stat_name_width : 50;
+       line_prefix = diff_line_prefix(options);
+       count = options->stat_count ? options->stat_count : data->nr;
 
-       /* Sanity: give at least 5 columns to the graph,
-        * but leave at least 10 columns for the name.
-        */
-       if (width < 25)
-               width = 25;
-       if (name_width < 10)
-               name_width = 10;
-       else if (width < name_width + 15)
-               name_width = width - 15;
-
-       /* Find the longest filename and max number of changes */
        reset = diff_get_color_opt(options, DIFF_RESET);
-       set   = diff_get_color_opt(options, DIFF_PLAIN);
        add_c = diff_get_color_opt(options, DIFF_FILE_NEW);
        del_c = diff_get_color_opt(options, DIFF_FILE_OLD);
 
-       for (i = 0; i < data->nr; i++) {
+       /*
+        * Find the longest filename and max number of changes
+        */
+       for (i = 0; (i < count) && (i < data->nr); i++) {
                struct diffstat_file *file = data->files[i];
                uintmax_t change = file->added + file->deleted;
+
+               if (!file->is_interesting && (change == 0)) {
+                       count++; /* not shown == room for one more */
+                       continue;
+               }
                fill_print_name(file);
                len = strlen(file->print_name);
                if (max_len < len)
                        max_len = len;
 
-               if (file->is_binary || file->is_unmerged)
+               if (file->is_unmerged) {
+                       /* "Unmerged" is 8 characters */
+                       bin_width = bin_width < 8 ? 8 : bin_width;
                        continue;
+               }
+               if (file->is_binary) {
+                       /* "Bin XXX -> YYY bytes" */
+                       int w = 14 + decimal_width(file->added)
+                               + decimal_width(file->deleted);
+                       bin_width = bin_width < w ? w : bin_width;
+                       /* Display change counts aligned with "Bin" */
+                       number_width = 3;
+                       continue;
+               }
+
                if (max_change < change)
                        max_change = change;
        }
+       count = i; /* where we can stop scanning in data->files[] */
 
-       /* Compute the width of the graph part;
-        * 10 is for one blank at the beginning of the line plus
-        * " | count " between the name and the graph.
+       /*
+        * We have width = stat_width or term_columns() columns total.
+        * We want a maximum of min(max_len, stat_name_width) for the name part.
+        * We want a maximum of min(max_change, stat_graph_width) for the +- part.
+        * We also need 1 for " " and 4 + decimal_width(max_change)
+        * for " | NNNN " and one the empty column at the end, altogether
+        * 6 + decimal_width(max_change).
+        *
+        * If there's not enough space, we will use the smaller of
+        * stat_name_width (if set) and 5/8*width for the filename,
+        * and the rest for constant elements + graph part, but no more
+        * than stat_graph_width for the graph part.
+        * (5/8 gives 50 for filename and 30 for the constant parts + graph
+        * for the standard terminal size).
+        *
+        * In other words: stat_width limits the maximum width, and
+        * stat_name_width fixes the maximum width of the filename,
+        * and is also used to divide available columns if there
+        * aren't enough.
         *
-        * From here on, name_width is the width of the name area,
-        * and width is the width of the graph area.
+        * Binary files are displayed with "Bin XXX -> YYY bytes"
+        * instead of the change count and graph. This part is treated
+        * similarly to the graph part, except that it is not
+        * "scaled". If total width is too small to accommodate the
+        * guaranteed minimum width of the filename part and the
+        * separators and this message, this message will "overflow"
+        * making the line longer than the maximum width.
         */
-       name_width = (name_width < max_len) ? name_width : max_len;
-       if (width < (name_width + 10) + max_change)
-               width = width - (name_width + 10);
+
+       if (options->stat_width == -1)
+               width = term_columns() - options->output_prefix_length;
        else
-               width = max_change;
+               width = options->stat_width ? options->stat_width : 80;
+       number_width = decimal_width(max_change) > number_width ?
+               decimal_width(max_change) : number_width;
 
-       for (i = 0; i < data->nr; i++) {
+       if (options->stat_graph_width == -1)
+               options->stat_graph_width = diff_stat_graph_width;
+
+       /*
+        * Guarantee 3/8*16==6 for the graph part
+        * and 5/8*16==10 for the filename part
+        */
+       if (width < 16 + 6 + number_width)
+               width = 16 + 6 + number_width;
+
+       /*
+        * First assign sizes that are wanted, ignoring available width.
+        * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
+        * starting from "XXX" should fit in graph_width.
+        */
+       graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
+       if (options->stat_graph_width &&
+           options->stat_graph_width < graph_width)
+               graph_width = options->stat_graph_width;
+
+       name_width = (options->stat_name_width > 0 &&
+                     options->stat_name_width < max_len) ?
+               options->stat_name_width : max_len;
+
+       /*
+        * Adjust adjustable widths not to exceed maximum width
+        */
+       if (name_width + number_width + 6 + graph_width > width) {
+               if (graph_width > width * 3/8 - number_width - 6) {
+                       graph_width = width * 3/8 - number_width - 6;
+                       if (graph_width < 6)
+                               graph_width = 6;
+               }
+
+               if (options->stat_graph_width &&
+                   graph_width > options->stat_graph_width)
+                       graph_width = options->stat_graph_width;
+               if (name_width > width - number_width - 6 - graph_width)
+                       name_width = width - number_width - 6 - graph_width;
+               else
+                       graph_width = width - number_width - 6 - name_width;
+       }
+
+       /*
+        * From here name_width is the width of the name area,
+        * and graph_width is the width of the graph area.
+        * max_change is used to scale graph properly.
+        */
+       for (i = 0; i < count; i++) {
                const char *prefix = "";
-               char *name = data->files[i]->print_name;
-               uintmax_t added = data->files[i]->added;
-               uintmax_t deleted = data->files[i]->deleted;
+               struct diffstat_file *file = data->files[i];
+               char *name = file->print_name;
+               uintmax_t added = file->added;
+               uintmax_t deleted = file->deleted;
                int name_len;
 
+               if (!file->is_interesting && (added + deleted == 0))
+                       continue;
+
                /*
                 * "scale" the filename
                 */
@@ -1315,11 +1647,15 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                                name = slash;
                }
 
-               if (data->files[i]->is_binary) {
+               if (file->is_binary) {
                        fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
-                       fprintf(options->file, "  Bin ");
-                       fprintf(options->file, "%s%"PRIuMAX"%s",
+                       fprintf(options->file, " %*s", number_width, "Bin");
+                       if (!added && !deleted) {
+                               putc('\n', options->file);
+                               continue;
+                       }
+                       fprintf(options->file, " %s%"PRIuMAX"%s",
                                del_c, deleted, reset);
                        fprintf(options->file, " -> ");
                        fprintf(options->file, "%s%"PRIuMAX"%s",
@@ -1328,15 +1664,10 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                        fprintf(options->file, "\n");
                        continue;
                }
-               else if (data->files[i]->is_unmerged) {
+               else if (file->is_unmerged) {
                        fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
-                       fprintf(options->file, "  Unmerged\n");
-                       continue;
-               }
-               else if (!data->files[i]->is_renamed &&
-                        (added + deleted == 0)) {
-                       total_files--;
+                       fprintf(options->file, " Unmerged\n");
                        continue;
                }
 
@@ -1345,25 +1676,53 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                 */
                add = added;
                del = deleted;
-               adds += add;
-               dels += del;
 
-               if (width <= max_change) {
-                       add = scale_linear(add, width, max_change);
-                       del = scale_linear(del, width, max_change);
+               if (graph_width <= max_change) {
+                       int total = scale_linear(add + del, graph_width, max_change);
+                       if (total < 2 && add && del)
+                               /* width >= 2 due to the sanity check */
+                               total = 2;
+                       if (add < del) {
+                               add = scale_linear(add, graph_width, max_change);
+                               del = total - add;
+                       } else {
+                               del = scale_linear(del, graph_width, max_change);
+                               add = total - del;
+                       }
                }
                fprintf(options->file, "%s", line_prefix);
                show_name(options->file, prefix, name, len);
-               fprintf(options->file, "%5"PRIuMAX"%s", added + deleted,
-                               added + deleted ? " " : "");
+               fprintf(options->file, " %*"PRIuMAX"%s",
+                       number_width, added + deleted,
+                       added + deleted ? " " : "");
                show_graph(options->file, '+', add, add_c, reset);
                show_graph(options->file, '-', del, del_c, reset);
                fprintf(options->file, "\n");
        }
+
+       for (i = 0; i < data->nr; i++) {
+               struct diffstat_file *file = data->files[i];
+               uintmax_t added = file->added;
+               uintmax_t deleted = file->deleted;
+
+               if (file->is_unmerged ||
+                   (!file->is_interesting && (added + deleted == 0))) {
+                       total_files--;
+                       continue;
+               }
+
+               if (!file->is_binary) {
+                       adds += added;
+                       dels += deleted;
+               }
+               if (i < count)
+                       continue;
+               if (!extra_shown)
+                       fprintf(options->file, "%s ...\n", line_prefix);
+               extra_shown = 1;
+       }
        fprintf(options->file, "%s", line_prefix);
-       fprintf(options->file,
-              " %d files changed, %d insertions(+), %d deletions(-)\n",
-              total_files, adds, dels);
+       print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
@@ -1374,27 +1733,19 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
                return;
 
        for (i = 0; i < data->nr; i++) {
-               if (!data->files[i]->is_binary &&
-                   !data->files[i]->is_unmerged) {
-                       int added = data->files[i]->added;
-                       int deleted= data->files[i]->deleted;
-                       if (!data->files[i]->is_renamed &&
-                           (added + deleted == 0)) {
-                               total_files--;
-                       } else {
-                               adds += added;
-                               dels += deleted;
-                       }
+               int added = data->files[i]->added;
+               int deleted= data->files[i]->deleted;
+
+               if (data->files[i]->is_unmerged ||
+                   (!data->files[i]->is_interesting && (added + deleted == 0))) {
+                       total_files--;
+               } else if (!data->files[i]->is_binary) { /* don't count bytes */
+                       adds += added;
+                       dels += deleted;
                }
        }
-       if (options->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = options->output_prefix(options,
-                               options->output_prefix_data);
-               fprintf(options->file, "%s", msg->buf);
-       }
-       fprintf(options->file, " %d files changed, %d insertions(+), %d deletions(-)\n",
-              total_files, adds, dels);
+       fprintf(options->file, "%s", diff_line_prefix(options));
+       print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_numstat(struct diffstat_t *data, struct diff_options *options)
@@ -1407,12 +1758,7 @@ static void show_numstat(struct diffstat_t *data, struct diff_options *options)
        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
 
-               if (options->output_prefix) {
-                       struct strbuf *msg = NULL;
-                       msg = options->output_prefix(options,
-                                       options->output_prefix_data);
-                       fprintf(options->file, "%s", msg->buf);
-               }
+               fprintf(options->file, "%s", diff_line_prefix(options));
 
                if (file->is_binary)
                        fprintf(options->file, "-\t-\t");
@@ -1446,7 +1792,7 @@ struct dirstat_file {
 
 struct dirstat_dir {
        struct dirstat_file *files;
-       int alloc, nr, percent, cumulative;
+       int alloc, nr, permille, cumulative;
 };
 
 static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
@@ -1454,13 +1800,7 @@ static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
 {
        unsigned long this_dir = 0;
        unsigned int sources = 0;
-       const char *line_prefix = "";
-       struct strbuf *msg = NULL;
-
-       if (opt->output_prefix) {
-               msg = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msg->buf;
-       }
+       const char *line_prefix = diff_line_prefix(opt);
 
        while (dir->nr) {
                struct dirstat_file *f = dir->files;
@@ -1493,12 +1833,11 @@ static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
         *    under this directory (sources == 1).
         */
        if (baselen && sources != 1) {
-               int permille = this_dir * 1000 / changed;
-               if (permille) {
-                       int percent = permille / 10;
-                       if (percent >= dir->percent) {
+               if (this_dir) {
+                       int permille = this_dir * 1000 / changed;
+                       if (permille >= dir->permille) {
                                fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
-                                       percent, permille % 10, baselen, base);
+                                       permille / 10, permille % 10, baselen, base);
                                if (!dir->cumulative)
                                        return 0;
                        }
@@ -1524,7 +1863,7 @@ static void show_dirstat(struct diff_options *options)
        dir.files = NULL;
        dir.alloc = 0;
        dir.nr = 0;
-       dir.percent = options->dirstat_percent;
+       dir.permille = options->dirstat_permille;
        dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
 
        changed = 0;
@@ -1532,8 +1871,36 @@ static void show_dirstat(struct diff_options *options)
                struct diff_filepair *p = q->queue[i];
                const char *name;
                unsigned long copied, added, damage;
+               int content_changed;
+
+               name = p->two->path ? p->two->path : p->one->path;
+
+               if (p->one->sha1_valid && p->two->sha1_valid)
+                       content_changed = hashcmp(p->one->sha1, p->two->sha1);
+               else
+                       content_changed = 1;
+
+               if (!content_changed) {
+                       /*
+                        * The SHA1 has not changed, so pre-/post-content is
+                        * identical. We can therefore skip looking at the
+                        * file contents altogether.
+                        */
+                       damage = 0;
+                       goto found_damage;
+               }
 
-               name = p->one->path ? p->one->path : p->two->path;
+               if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE)) {
+                       /*
+                        * In --dirstat-by-file mode, we don't really need to
+                        * look at the actual file contents at all.
+                        * The fact that the SHA1 changed is enough for us to
+                        * add this file to the list of results
+                        * (with each file contributing equal damage).
+                        */
+                       damage = 1;
+                       goto found_damage;
+               }
 
                if (DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
                        diff_populate_filespec(p->one, 0);
@@ -1557,14 +1924,18 @@ static void show_dirstat(struct diff_options *options)
                /*
                 * Original minus copied is the removed material,
                 * added is the new material.  They are both damages
-                * made to the preimage. In --dirstat-by-file mode, count
-                * damaged files, not damaged lines. This is done by
-                * counting only a single damaged line per file.
+                * made to the preimage.
+                * If the resulting damage is zero, we know that
+                * diffcore_count_changes() considers the two entries to
+                * be identical, but since content_changed is true, we
+                * know that there must have been _some_ kind of change,
+                * so we force all entries to have damage > 0.
                 */
                damage = (p->one->size - copied) + added;
-               if (DIFF_OPT_TST(options, DIRSTAT_BY_FILE) && damage > 0)
+               if (!damage)
                        damage = 1;
 
+found_damage:
                ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
                dir.files[dir.nr].name = name;
                dir.files[dir.nr].changed = damage;
@@ -1581,6 +1952,50 @@ static void show_dirstat(struct diff_options *options)
        gather_dirstat(options, &dir, changed, "", 0);
 }
 
+static void show_dirstat_by_line(struct diffstat_t *data, struct diff_options *options)
+{
+       int i;
+       unsigned long changed;
+       struct dirstat_dir dir;
+
+       if (data->nr == 0)
+               return;
+
+       dir.files = NULL;
+       dir.alloc = 0;
+       dir.nr = 0;
+       dir.permille = options->dirstat_permille;
+       dir.cumulative = DIFF_OPT_TST(options, DIRSTAT_CUMULATIVE);
+
+       changed = 0;
+       for (i = 0; i < data->nr; i++) {
+               struct diffstat_file *file = data->files[i];
+               unsigned long damage = file->added + file->deleted;
+               if (file->is_binary)
+                       /*
+                        * binary files counts bytes, not lines. Must find some
+                        * way to normalize binary bytes vs. textual lines.
+                        * The following heuristic assumes that there are 64
+                        * bytes per "line".
+                        * This is stupid and ugly, but very cheap...
+                        */
+                       damage = (damage + 63) / 64;
+               ALLOC_GROW(dir.files, dir.nr + 1, dir.alloc);
+               dir.files[dir.nr].name = file->name;
+               dir.files[dir.nr].changed = damage;
+               changed += damage;
+               dir.nr++;
+       }
+
+       /* This can happen even with many files, if everything was renames */
+       if (!changed)
+               return;
+
+       /* Show all directories with more than x% of the changes */
+       qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
+       gather_dirstat(options, &dir, changed, "", 0);
+}
+
 static void free_diffstat_info(struct diffstat_t *diffstat)
 {
        int i;
@@ -1630,21 +2045,15 @@ static int is_conflict_marker(const char *line, int marker_size, unsigned long l
 static void checkdiff_consume(void *priv, char *line, unsigned long len)
 {
        struct checkdiff_t *data = priv;
-       int color_diff = DIFF_OPT_TST(data->o, COLOR_DIFF);
        int marker_size = data->conflict_marker_size;
-       const char *ws = diff_get_color(color_diff, DIFF_WHITESPACE);
-       const char *reset = diff_get_color(color_diff, DIFF_RESET);
-       const char *set = diff_get_color(color_diff, DIFF_FILE_NEW);
+       const char *ws = diff_get_color(data->o->use_color, DIFF_WHITESPACE);
+       const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
+       const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
        char *err;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
+       const char *line_prefix;
 
        assert(data->o);
-       if (data->o->output_prefix) {
-               msgbuf = data->o->output_prefix(data->o,
-                       data->o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(data->o);
 
        if (line[0] == '+') {
                unsigned bad;
@@ -1683,25 +2092,26 @@ static unsigned char *deflate_it(char *data,
 {
        int bound;
        unsigned char *deflated;
-       z_stream stream;
+       git_zstream stream;
 
        memset(&stream, 0, sizeof(stream));
-       deflateInit(&stream, zlib_compression_level);
-       bound = deflateBound(&stream, size);
+       git_deflate_init(&stream, zlib_compression_level);
+       bound = git_deflate_bound(&stream, size);
        deflated = xmalloc(bound);
        stream.next_out = deflated;
        stream.avail_out = bound;
 
        stream.next_in = (unsigned char *)data;
        stream.avail_in = size;
-       while (deflate(&stream, Z_FINISH) == Z_OK)
+       while (git_deflate(&stream, Z_FINISH) == Z_OK)
                ; /* nothing */
-       deflateEnd(&stream);
+       git_deflate_end(&stream);
        *result_size = stream.total_out;
        return deflated;
 }
 
-static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
+                                 const char *prefix)
 {
        void *cp;
        void *delta;
@@ -1762,27 +2172,14 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char
        free(data);
 }
 
-static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
+                            const char *prefix)
 {
        fprintf(file, "%sGIT binary patch\n", prefix);
        emit_binary_diff_body(file, one, two, prefix);
        emit_binary_diff_body(file, two, one, prefix);
 }
 
-static void diff_filespec_load_driver(struct diff_filespec *one)
-{
-       /* Use already-loaded driver */
-       if (one->driver)
-               return;
-
-       if (S_ISREG(one->mode))
-               one->driver = userdiff_find_by_path(one->path);
-
-       /* Fallback to default settings */
-       if (!one->driver)
-               one->driver = userdiff_find_by_name("default");
-}
-
 int diff_filespec_is_binary(struct diff_filespec *one)
 {
        if (one->is_binary == -1) {
@@ -1808,12 +2205,6 @@ static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespe
        return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
 }
 
-static const char *userdiff_word_regex(struct diff_filespec *one)
-{
-       diff_filespec_load_driver(one);
-       return one->driver->word_regex;
-}
-
 void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
 {
        if (!options->a_prefix)
@@ -1828,19 +2219,7 @@ struct userdiff_driver *get_textconv(struct diff_filespec *one)
                return NULL;
 
        diff_filespec_load_driver(one);
-       if (!one->driver->textconv)
-               return NULL;
-
-       if (one->driver->textconv_want_cache && !one->driver->textconv_cache) {
-               struct notes_cache *c = xmalloc(sizeof(*c));
-               struct strbuf name = STRBUF_INIT;
-
-               strbuf_addf(&name, "textconv/%s", one->driver->name);
-               notes_cache_init(c, name.buf, one->driver->textconv);
-               one->driver->textconv_cache = c;
-       }
-
-       return one->driver;
+       return userdiff_get_textconv(one->driver);
 }
 
 static void builtin_diff(const char *name_a,
@@ -1855,28 +2234,23 @@ static void builtin_diff(const char *name_a,
        mmfile_t mf1, mf2;
        const char *lbl[2];
        char *a_one, *b_two;
-       const char *set = diff_get_color_opt(o, DIFF_METAINFO);
+       const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
        struct userdiff_driver *textconv_one = NULL;
        struct userdiff_driver *textconv_two = NULL;
        struct strbuf header = STRBUF_INIT;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
-
-       if (o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
                        (!one->mode || S_ISGITLINK(one->mode)) &&
                        (!two->mode || S_ISGITLINK(two->mode))) {
                const char *del = diff_get_color_opt(o, DIFF_FILE_OLD);
                const char *add = diff_get_color_opt(o, DIFF_FILE_NEW);
-               show_submodule_summary(o->file, one ? one->path : two->path,
+               show_submodule_summary(o->file, one->path ? one->path : two->path,
+                               line_prefix,
                                one->sha1, two->sha1, two->dirty_submodule,
-                               del, add, reset);
+                               meta, del, add, reset);
                return;
        }
 
@@ -1902,24 +2276,24 @@ static void builtin_diff(const char *name_a,
        b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, set, a_one, b_two, reset);
+       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
-               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, set, two->mode, reset);
+               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
-               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, set, one->mode, reset);
+               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
-                       strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, set, one->mode, reset);
-                       strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, set, two->mode, reset);
+                       strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
+                       strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
                        must_show_header = 1;
                }
                if (xfrm_msg)
@@ -1943,7 +2317,11 @@ static void builtin_diff(const char *name_a,
                }
        }
 
-       if (!DIFF_OPT_TST(o, TEXT) &&
+       if (o->irreversible_delete && lbl[1][0] == '/') {
+               fprintf(o->file, "%s", header.buf);
+               strbuf_reset(&header);
+               goto free_ab_and_return;
+       } else if (!DIFF_OPT_TST(o, TEXT) &&
            ( (!textconv_one && diff_filespec_is_binary(one)) ||
              (!textconv_two && diff_filespec_is_binary(two)) )) {
                if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
@@ -1963,10 +2341,10 @@ static void builtin_diff(const char *name_a,
                        fprintf(o->file, "%sBinary files %s and %s differ\n",
                                line_prefix, lbl[0], lbl[1]);
                o->found_changes = 1;
-       }
-       else {
+       } else {
                /* Crazy xdl interfaces.. */
                const char *diffopts = getenv("GIT_DIFF_OPTS");
+               const char *v;
                xpparam_t xpp;
                xdemitconf_t xecfg;
                struct emit_callback ecbdata;
@@ -1988,9 +2366,9 @@ static void builtin_diff(const char *name_a,
                memset(&xecfg, 0, sizeof(xecfg));
                memset(&ecbdata, 0, sizeof(ecbdata));
                ecbdata.label_path = lbl;
-               ecbdata.color_diff = DIFF_OPT_TST(o, COLOR_DIFF);
+               ecbdata.color_diff = want_color(o->use_color);
                ecbdata.found_changesp = &o->found_changes;
-               ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
+               ecbdata.ws_rule = whitespace_rule(name_b);
                if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
                ecbdata.opt = o;
@@ -1999,50 +2377,18 @@ static void builtin_diff(const char *name_a,
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
+               if (DIFF_OPT_TST(o, FUNCCONTEXT))
+                       xecfg.flags |= XDL_EMIT_FUNCCONTEXT;
                if (pe)
                        xdiff_set_find_func(&xecfg, pe->pattern, pe->cflags);
                if (!diffopts)
                        ;
-               else if (!prefixcmp(diffopts, "--unified="))
-                       xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
-               else if (!prefixcmp(diffopts, "-u"))
-                       xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-               if (o->word_diff) {
-                       int i;
-
-                       ecbdata.diff_words =
-                               xcalloc(1, sizeof(struct diff_words_data));
-                       ecbdata.diff_words->type = o->word_diff;
-                       ecbdata.diff_words->opt = o;
-                       if (!o->word_regex)
-                               o->word_regex = userdiff_word_regex(one);
-                       if (!o->word_regex)
-                               o->word_regex = userdiff_word_regex(two);
-                       if (!o->word_regex)
-                               o->word_regex = diff_word_regex_cfg;
-                       if (o->word_regex) {
-                               ecbdata.diff_words->word_regex = (regex_t *)
-                                       xmalloc(sizeof(regex_t));
-                               if (regcomp(ecbdata.diff_words->word_regex,
-                                               o->word_regex,
-                                               REG_EXTENDED | REG_NEWLINE))
-                                       die ("Invalid regular expression: %s",
-                                                       o->word_regex);
-                       }
-                       for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
-                               if (o->word_diff == diff_words_styles[i].type) {
-                                       ecbdata.diff_words->style =
-                                               &diff_words_styles[i];
-                                       break;
-                               }
-                       }
-                       if (DIFF_OPT_TST(o, COLOR_DIFF)) {
-                               struct diff_words_style *st = ecbdata.diff_words->style;
-                               st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
-                               st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
-                               st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
-                       }
-               }
+               else if (skip_prefix(diffopts, "--unified=", &v))
+                       xecfg.ctxlen = strtoul(v, NULL, 10);
+               else if (skip_prefix(diffopts, "-u", &v))
+                       xecfg.ctxlen = strtoul(v, NULL, 10);
+               if (o->word_diff)
+                       init_diff_words_data(&ecbdata, o, one, two);
                xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
                              &xpp, &xecfg);
                if (o->word_diff)
@@ -2068,44 +2414,63 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                             struct diff_filespec *two,
                             struct diffstat_t *diffstat,
                             struct diff_options *o,
-                            int complete_rewrite)
+                            struct diff_filepair *p)
 {
        mmfile_t mf1, mf2;
        struct diffstat_file *data;
+       int same_contents;
+       int complete_rewrite = 0;
+
+       if (!DIFF_PAIR_UNMERGED(p)) {
+               if (p->status == DIFF_STATUS_MODIFIED && p->score)
+                       complete_rewrite = 1;
+       }
 
        data = diffstat_add(diffstat, name_a, name_b);
+       data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
 
        if (!one || !two) {
                data->is_unmerged = 1;
                return;
        }
-       if (complete_rewrite) {
+
+       same_contents = !hashcmp(one->sha1, two->sha1);
+
+       if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
+               data->is_binary = 1;
+               if (same_contents) {
+                       data->added = 0;
+                       data->deleted = 0;
+               } else {
+                       data->added = diff_filespec_size(two);
+                       data->deleted = diff_filespec_size(one);
+               }
+       }
+
+       else if (complete_rewrite) {
                diff_populate_filespec(one, 0);
                diff_populate_filespec(two, 0);
                data->deleted = count_lines(one->data, one->size);
                data->added = count_lines(two->data, two->size);
-               goto free_and_return;
        }
-       if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-               die("unable to read files to diff");
 
-       if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
-               data->is_binary = 1;
-               data->added = mf2.size;
-               data->deleted = mf1.size;
-       } else {
+       else if (!same_contents) {
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;
 
+               if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
+                       die("unable to read files to diff");
+
                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                xpp.flags = o->xdl_opts;
+               xecfg.ctxlen = o->context;
+               xecfg.interhunkctxlen = o->interhunkcontext;
                xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
                              &xpp, &xecfg);
        }
 
- free_and_return:
        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
 }
@@ -2158,7 +2523,7 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
 
                        ecbdata.ws_rule = data.ws_rule;
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
-                       blank_at_eof = ecbdata.blank_at_eof_in_preimage;
+                       blank_at_eof = ecbdata.blank_at_eof_in_postimage;
 
                        if (blank_at_eof) {
                                static char *err;
@@ -2199,12 +2564,12 @@ void free_filespec(struct diff_filespec *spec)
 }
 
 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
-                  unsigned short mode)
+                  int sha1_valid, unsigned short mode)
 {
        if (mode) {
                spec->mode = canon_mode(mode);
                hashcpy(spec->sha1, sha1);
-               spec->sha1_valid = !is_null_sha1(sha1);
+               spec->sha1_valid = sha1_valid;
        }
 }
 
@@ -2215,7 +2580,7 @@ void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
  */
 static int reuse_worktree_file(const char *name, const unsigned char *sha1, int want_file)
 {
-       struct cache_entry *ce;
+       const struct cache_entry *ce;
        struct stat st;
        int pos, len;
 
@@ -2277,22 +2642,6 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int
        return 0;
 }
 
-static int populate_from_stdin(struct diff_filespec *s)
-{
-       struct strbuf buf = STRBUF_INIT;
-       size_t size = 0;
-
-       if (strbuf_read(&buf, 0, 0) < 0)
-               return error("error while reading from stdin %s",
-                                    strerror(errno));
-
-       s->should_munmap = 0;
-       s->data = strbuf_detach(&buf, &size);
-       s->size = size;
-       s->should_free = 1;
-       return 0;
-}
-
 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 {
        int len;
@@ -2322,6 +2671,14 @@ static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 int diff_populate_filespec(struct diff_filespec *s, int size_only)
 {
        int err = 0;
+       /*
+        * demote FAIL to WARN to allow inspecting the situation
+        * instead of refusing.
+        */
+       enum safe_crlf crlf_warn = (safe_crlf == SAFE_CRLF_FAIL
+                                   ? SAFE_CRLF_WARN
+                                   : safe_crlf);
+
        if (!DIFF_FILE_VALID(s))
                die("internal error: asking to populate invalid file.");
        if (S_ISDIR(s->mode))
@@ -2342,9 +2699,6 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
                struct stat st;
                int fd;
 
-               if (!strcmp(s->path, "-"))
-                       return populate_from_stdin(s);
-
                if (lstat(s->path, &st) < 0) {
                        if (errno == ENOENT) {
                        err_empty:
@@ -2380,7 +2734,7 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
                /*
                 * Convert from working tree format to canonical git format
                 */
-               if (convert_to_git(s->path, s->data, s->size, &buf, safe_crlf)) {
+               if (convert_to_git(s->path, s->data, s->size, &buf, crlf_warn)) {
                        size_t size = 0;
                        munmap(s->data, s->size);
                        s->should_munmap = 0;
@@ -2391,10 +2745,14 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
        }
        else {
                enum object_type type;
-               if (size_only)
+               if (size_only) {
                        type = sha1_object_info(s->sha1, &s->size);
-               else {
+                       if (type < 0)
+                               die("unable to read %s", sha1_to_hex(s->sha1));
+               } else {
                        s->data = read_sha1_file(s->sha1, &type, &s->size);
+                       if (!s->data)
+                               die("unable to read %s", sha1_to_hex(s->sha1));
                        s->should_free = 1;
                }
        }
@@ -2480,8 +2838,9 @@ static struct diff_tempfile *prepare_temp_file(const char *name,
                remove_tempfile_installed = 1;
        }
 
-       if (!one->sha1_valid ||
-           reuse_worktree_file(name, one->sha1, 1)) {
+       if (!S_ISGITLINK(one->mode) &&
+           (!one->sha1_valid ||
+            reuse_worktree_file(name, one->sha1, 1))) {
                struct stat st;
                if (lstat(name, &st) < 0) {
                        if (errno == ENOENT)
@@ -2525,6 +2884,16 @@ static struct diff_tempfile *prepare_temp_file(const char *name,
        return temp;
 }
 
+static void add_external_diff_name(struct argv_array *argv,
+                                  const char *name,
+                                  struct diff_filespec *df)
+{
+       struct diff_tempfile *temp = prepare_temp_file(name, df);
+       argv_array_push(argv, temp->name);
+       argv_array_push(argv, temp->hex);
+       argv_array_push(argv, temp->mode);
+}
+
 /* An external diff command takes:
  *
  * diff-cmd name infile1 infile1-sha1 infile1-mode \
@@ -2537,41 +2906,36 @@ static void run_external_diff(const char *pgm,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
                              const char *xfrm_msg,
-                             int complete_rewrite)
+                             int complete_rewrite,
+                             struct diff_options *o)
 {
-       const char *spawn_arg[10];
-       int retval;
-       const char **arg = &spawn_arg[0];
+       struct argv_array argv = ARGV_ARRAY_INIT;
+       struct argv_array env = ARGV_ARRAY_INIT;
+       struct diff_queue_struct *q = &diff_queued_diff;
+
+       argv_array_push(&argv, pgm);
+       argv_array_push(&argv, name);
 
        if (one && two) {
-               struct diff_tempfile *temp_one, *temp_two;
-               const char *othername = (other ? other : name);
-               temp_one = prepare_temp_file(name, one);
-               temp_two = prepare_temp_file(othername, two);
-               *arg++ = pgm;
-               *arg++ = name;
-               *arg++ = temp_one->name;
-               *arg++ = temp_one->hex;
-               *arg++ = temp_one->mode;
-               *arg++ = temp_two->name;
-               *arg++ = temp_two->hex;
-               *arg++ = temp_two->mode;
-               if (other) {
-                       *arg++ = other;
-                       *arg++ = xfrm_msg;
+               add_external_diff_name(&argv, name, one);
+               if (!other)
+                       add_external_diff_name(&argv, name, two);
+               else {
+                       add_external_diff_name(&argv, other, two);
+                       argv_array_push(&argv, other);
+                       argv_array_push(&argv, xfrm_msg);
                }
-       } else {
-               *arg++ = pgm;
-               *arg++ = name;
        }
-       *arg = NULL;
-       fflush(NULL);
-       retval = run_command_v_opt(spawn_arg, RUN_USING_SHELL);
+
+       argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);
+       argv_array_pushf(&env, "GIT_DIFF_PATH_TOTAL=%d", q->nr);
+
+       if (run_command_v_opt_cd_env(argv.argv, RUN_USING_SHELL, NULL, env.argv))
+               die(_("external diff died, stopping at %s"), name);
+
        remove_tempfile();
-       if (retval) {
-               fprintf(stderr, "external diff died, stopping at %s.\n", name);
-               exit(1);
-       }
+       argv_array_clear(&argv);
+       argv_array_clear(&env);
 }
 
 static int similarity_index(struct diff_filepair *p)
@@ -2591,14 +2955,9 @@ static void fill_metainfo(struct strbuf *msg,
 {
        const char *set = diff_get_color(use_color, DIFF_METAINFO);
        const char *reset = diff_get_color(use_color, DIFF_RESET);
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix = diff_line_prefix(o);
 
        *must_show_header = 1;
-       if (o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
        strbuf_init(msg, PATH_MAX * 2 + 300);
        switch (p->status) {
        case DIFF_STATUS_COPIED:
@@ -2665,9 +3024,8 @@ static void run_diff_cmd(const char *pgm,
        int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
        int must_show_header = 0;
 
-       if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
-               pgm = NULL;
-       else {
+
+       if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
                struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
                if (drv && drv->external)
                        pgm = drv->external;
@@ -2680,13 +3038,13 @@ static void run_diff_cmd(const char *pgm,
                 */
                fill_metainfo(msg, name, other, one, two, o, p,
                              &must_show_header,
-                             DIFF_OPT_TST(o, COLOR_DIFF) && !pgm);
+                             want_color(o->use_color) && !pgm);
                xfrm_msg = msg->len ? msg->buf : NULL;
        }
 
        if (pgm) {
                run_external_diff(pgm, name, other, one, two, xfrm_msg,
-                                 complete_rewrite);
+                                 complete_rewrite, o);
                return;
        }
        if (one && two)
@@ -2702,7 +3060,7 @@ static void diff_fill_sha1_info(struct diff_filespec *one)
        if (DIFF_FILE_VALID(one)) {
                if (!one->sha1_valid) {
                        struct stat st;
-                       if (!strcmp(one->path, "-")) {
+                       if (one->is_stdin) {
                                hashcpy(one->sha1, null_sha1);
                                return;
                        }
@@ -2747,6 +3105,9 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
        if (o->prefix_length)
                strip_prefix(o->prefix_length, &name, &other);
 
+       if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
+               pgm = NULL;
+
        if (DIFF_PAIR_UNMERGED(p)) {
                run_diff_cmd(pgm, name, NULL, attr_path,
                             NULL, NULL, NULL, o, p);
@@ -2786,11 +3147,10 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
 {
        const char *name;
        const char *other;
-       int complete_rewrite = 0;
 
        if (DIFF_PAIR_UNMERGED(p)) {
                /* unmerged */
-               builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, 0);
+               builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
                return;
        }
 
@@ -2803,9 +3163,7 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
        diff_fill_sha1_info(p->one);
        diff_fill_sha1_info(p->two);
 
-       if (p->status == DIFF_STATUS_MODIFIED && p->score)
-               complete_rewrite = 1;
-       builtin_diffstat(name, other, p->one, p->two, diffstat, o, complete_rewrite);
+       builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
 }
 
 static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
@@ -2841,14 +3199,18 @@ void diff_setup(struct diff_options *options)
        options->line_termination = '\n';
        options->break_opt = -1;
        options->rename_limit = -1;
-       options->dirstat_percent = 3;
-       options->context = 3;
+       options->dirstat_permille = diff_dirstat_permille_default;
+       options->context = diff_context_default;
+       DIFF_OPT_SET(options, RENAME_EMPTY);
 
+       /* pathchange left =NULL by default */
        options->change = diff_change;
        options->add_remove = diff_addremove;
-       if (diff_use_color_default > 0)
-               DIFF_OPT_SET(options, COLOR_DIFF);
+       options->use_color = diff_use_color_default;
        options->detect_rename = diff_detect_rename_default;
+       options->xdl_opts |= diff_algorithm;
+
+       options->orderfile = diff_order_file_cfg;
 
        if (diff_no_prefix) {
                options->a_prefix = options->b_prefix = "";
@@ -2858,10 +3220,13 @@ void diff_setup(struct diff_options *options)
        }
 }
 
-int diff_setup_done(struct diff_options *options)
+void diff_setup_done(struct diff_options *options)
 {
        int count = 0;
 
+       if (options->set_default)
+               options->set_default(options);
+
        if (options->output_format & DIFF_FORMAT_NAME)
                count++;
        if (options->output_format & DIFF_FORMAT_NAME_STATUS)
@@ -2958,7 +3323,10 @@ int diff_setup_done(struct diff_options *options)
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        }
 
-       return 0;
+       options->diff_path_counter = 0;
+
+       if (DIFF_OPT_TST(options, FOLLOW_RENAMES) && options->pathspec.nr != 1)
+               die(_("--follow requires exactly one pathspec"));
 }
 
 static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
@@ -2988,14 +3356,11 @@ static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *va
        if (c != '-')
                return 0;
        arg++;
-       eq = strchr(arg, '=');
-       if (eq)
-               len = eq - arg;
-       else
-               len = strlen(arg);
+       eq = strchrnul(arg, '=');
+       len = eq - arg;
        if (!len || strncmp(arg, arg_long, len))
                return 0;
-       if (eq) {
+       if (*eq) {
                int n;
                char *end;
                if (!isdigit(*++eq))
@@ -3030,13 +3395,11 @@ int parse_long_opt(const char *opt, const char **argv,
                   const char **optarg)
 {
        const char *arg = argv[0];
-       if (arg[0] != '-' || arg[1] != '-')
+       if (!skip_prefix(arg, "--", &arg))
                return 0;
-       arg += strlen("--");
-       if (prefixcmp(arg, opt))
+       if (!skip_prefix(arg, opt, &arg))
                return 0;
-       arg += strlen(opt);
-       if (*arg == '=') { /* sticked form: --option=value */
+       if (*arg == '=') { /* stuck form: --option=value */
                *optarg = arg + 1;
                return 1;
        }
@@ -3055,15 +3418,17 @@ static int stat_opt(struct diff_options *options, const char **av)
        char *end;
        int width = options->stat_width;
        int name_width = options->stat_name_width;
+       int graph_width = options->stat_graph_width;
+       int count = options->stat_count;
        int argcount = 1;
 
-       arg += strlen("--stat");
+       if (!skip_prefix(arg, "--stat", &arg))
+               die("BUG: stat option does not begin with --stat: %s", arg);
        end = (char *)arg;
 
        switch (*arg) {
        case '-':
-               if (!prefixcmp(arg, "-width")) {
-                       arg += strlen("-width");
+               if (skip_prefix(arg, "-width", &arg)) {
                        if (*arg == '=')
                                width = strtoul(arg + 1, &end, 10);
                        else if (!*arg && !av[1])
@@ -3072,8 +3437,7 @@ static int stat_opt(struct diff_options *options, const char **av)
                                width = strtoul(av[1], &end, 10);
                                argcount = 2;
                        }
-               } else if (!prefixcmp(arg, "-name-width")) {
-                       arg += strlen("-name-width");
+               } else if (skip_prefix(arg, "-name-width", &arg)) {
                        if (*arg == '=')
                                name_width = strtoul(arg + 1, &end, 10);
                        else if (!*arg && !av[1])
@@ -3082,12 +3446,32 @@ static int stat_opt(struct diff_options *options, const char **av)
                                name_width = strtoul(av[1], &end, 10);
                                argcount = 2;
                        }
+               } else if (skip_prefix(arg, "-graph-width", &arg)) {
+                       if (*arg == '=')
+                               graph_width = strtoul(arg + 1, &end, 10);
+                       else if (!*arg && !av[1])
+                               die("Option '--stat-graph-width' requires a value");
+                       else if (!*arg) {
+                               graph_width = strtoul(av[1], &end, 10);
+                               argcount = 2;
+                       }
+               } else if (skip_prefix(arg, "-count", &arg)) {
+                       if (*arg == '=')
+                               count = strtoul(arg + 1, &end, 10);
+                       else if (!*arg && !av[1])
+                               die("Option '--stat-count' requires a value");
+                       else if (!*arg) {
+                               count = strtoul(av[1], &end, 10);
+                               argcount = 2;
+                       }
                }
                break;
        case '=':
                width = strtoul(arg+1, &end, 10);
                if (*end == ',')
                        name_width = strtoul(end+1, &end, 10);
+               if (*end == ',')
+                       count = strtoul(end+1, &end, 10);
        }
 
        /* Important! This checks all the error cases! */
@@ -3095,10 +3479,114 @@ static int stat_opt(struct diff_options *options, const char **av)
                return 0;
        options->output_format |= DIFF_FORMAT_DIFFSTAT;
        options->stat_name_width = name_width;
+       options->stat_graph_width = graph_width;
        options->stat_width = width;
+       options->stat_count = count;
        return argcount;
 }
 
+static int parse_dirstat_opt(struct diff_options *options, const char *params)
+{
+       struct strbuf errmsg = STRBUF_INIT;
+       if (parse_dirstat_params(options, params, &errmsg))
+               die(_("Failed to parse --dirstat/-X option parameter:\n%s"),
+                   errmsg.buf);
+       strbuf_release(&errmsg);
+       /*
+        * The caller knows a dirstat-related option is given from the command
+        * line; allow it to say "return this_function();"
+        */
+       options->output_format |= DIFF_FORMAT_DIRSTAT;
+       return 1;
+}
+
+static int parse_submodule_opt(struct diff_options *options, const char *value)
+{
+       if (parse_submodule_params(options, value))
+               die(_("Failed to parse --submodule option parameter: '%s'"),
+                       value);
+       return 1;
+}
+
+static const char diff_status_letters[] = {
+       DIFF_STATUS_ADDED,
+       DIFF_STATUS_COPIED,
+       DIFF_STATUS_DELETED,
+       DIFF_STATUS_MODIFIED,
+       DIFF_STATUS_RENAMED,
+       DIFF_STATUS_TYPE_CHANGED,
+       DIFF_STATUS_UNKNOWN,
+       DIFF_STATUS_UNMERGED,
+       DIFF_STATUS_FILTER_AON,
+       DIFF_STATUS_FILTER_BROKEN,
+       '\0',
+};
+
+static unsigned int filter_bit['Z' + 1];
+
+static void prepare_filter_bits(void)
+{
+       int i;
+
+       if (!filter_bit[DIFF_STATUS_ADDED]) {
+               for (i = 0; diff_status_letters[i]; i++)
+                       filter_bit[(int) diff_status_letters[i]] = (1 << i);
+       }
+}
+
+static unsigned filter_bit_tst(char status, const struct diff_options *opt)
+{
+       return opt->filter & filter_bit[(int) status];
+}
+
+static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
+{
+       int i, optch;
+
+       prepare_filter_bits();
+
+       /*
+        * If there is a negation e.g. 'd' in the input, and we haven't
+        * initialized the filter field with another --diff-filter, start
+        * from full set of bits, except for AON.
+        */
+       if (!opt->filter) {
+               for (i = 0; (optch = optarg[i]) != '\0'; i++) {
+                       if (optch < 'a' || 'z' < optch)
+                               continue;
+                       opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
+                       opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
+                       break;
+               }
+       }
+
+       for (i = 0; (optch = optarg[i]) != '\0'; i++) {
+               unsigned int bit;
+               int negate;
+
+               if ('a' <= optch && optch <= 'z') {
+                       negate = 1;
+                       optch = toupper(optch);
+               } else {
+                       negate = 0;
+               }
+
+               bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
+               if (!bit)
+                       return optarg[i];
+               if (negate)
+                       opt->filter &= ~bit;
+               else
+                       opt->filter |= bit;
+       }
+       return 0;
+}
+
+static void enable_patch_output(int *fmt) {
+       *fmt &= ~DIFF_FORMAT_NO_OUTPUT;
+       *fmt |= DIFF_FORMAT_PATCH;
+}
+
 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 {
        const char *arg = av[0];
@@ -3106,86 +3594,117 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        int argcount;
 
        /* Output format options */
-       if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch"))
-               options->output_format |= DIFF_FORMAT_PATCH;
-       else if (opt_arg(arg, 'U', "unified", &options->context))
-               options->output_format |= DIFF_FORMAT_PATCH;
+       if (!strcmp(arg, "-p") || !strcmp(arg, "-u") || !strcmp(arg, "--patch")
+           || opt_arg(arg, 'U', "unified", &options->context))
+               enable_patch_output(&options->output_format);
        else if (!strcmp(arg, "--raw"))
                options->output_format |= DIFF_FORMAT_RAW;
-       else if (!strcmp(arg, "--patch-with-raw"))
-               options->output_format |= DIFF_FORMAT_PATCH | DIFF_FORMAT_RAW;
-       else if (!strcmp(arg, "--numstat"))
+       else if (!strcmp(arg, "--patch-with-raw")) {
+               enable_patch_output(&options->output_format);
+               options->output_format |= DIFF_FORMAT_RAW;
+       } else if (!strcmp(arg, "--numstat"))
                options->output_format |= DIFF_FORMAT_NUMSTAT;
        else if (!strcmp(arg, "--shortstat"))
                options->output_format |= DIFF_FORMAT_SHORTSTAT;
-       else if (opt_arg(arg, 'X', "dirstat", &options->dirstat_percent))
-               options->output_format |= DIFF_FORMAT_DIRSTAT;
-       else if (!strcmp(arg, "--cumulative")) {
-               options->output_format |= DIFF_FORMAT_DIRSTAT;
-               DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
-       } else if (opt_arg(arg, 0, "dirstat-by-file",
-                          &options->dirstat_percent)) {
-               options->output_format |= DIFF_FORMAT_DIRSTAT;
-               DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
+       else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
+               return parse_dirstat_opt(options, "");
+       else if (skip_prefix(arg, "-X", &arg))
+               return parse_dirstat_opt(options, arg);
+       else if (skip_prefix(arg, "--dirstat=", &arg))
+               return parse_dirstat_opt(options, arg);
+       else if (!strcmp(arg, "--cumulative"))
+               return parse_dirstat_opt(options, "cumulative");
+       else if (!strcmp(arg, "--dirstat-by-file"))
+               return parse_dirstat_opt(options, "files");
+       else if (skip_prefix(arg, "--dirstat-by-file=", &arg)) {
+               parse_dirstat_opt(options, "files");
+               return parse_dirstat_opt(options, arg);
        }
        else if (!strcmp(arg, "--check"))
                options->output_format |= DIFF_FORMAT_CHECKDIFF;
        else if (!strcmp(arg, "--summary"))
                options->output_format |= DIFF_FORMAT_SUMMARY;
-       else if (!strcmp(arg, "--patch-with-stat"))
-               options->output_format |= DIFF_FORMAT_PATCH | DIFF_FORMAT_DIFFSTAT;
-       else if (!strcmp(arg, "--name-only"))
+       else if (!strcmp(arg, "--patch-with-stat")) {
+               enable_patch_output(&options->output_format);
+               options->output_format |= DIFF_FORMAT_DIFFSTAT;
+       } else if (!strcmp(arg, "--name-only"))
                options->output_format |= DIFF_FORMAT_NAME;
        else if (!strcmp(arg, "--name-status"))
                options->output_format |= DIFF_FORMAT_NAME_STATUS;
-       else if (!strcmp(arg, "-s"))
+       else if (!strcmp(arg, "-s") || !strcmp(arg, "--no-patch"))
                options->output_format |= DIFF_FORMAT_NO_OUTPUT;
-       else if (!prefixcmp(arg, "--stat"))
-               /* --stat, --stat-width, or --stat-name-width */
+       else if (starts_with(arg, "--stat"))
+               /* --stat, --stat-width, --stat-name-width, or --stat-count */
                return stat_opt(options, av);
 
        /* renames options */
-       else if (!prefixcmp(arg, "-B") || !prefixcmp(arg, "--break-rewrites=") ||
+       else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
                 !strcmp(arg, "--break-rewrites")) {
                if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
-                       return -1;
+                       return error("invalid argument to -B: %s", arg+2);
        }
-       else if (!prefixcmp(arg, "-M") || !prefixcmp(arg, "--detect-renames=") ||
-                !strcmp(arg, "--detect-renames")) {
+       else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
+                !strcmp(arg, "--find-renames")) {
                if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
-                       return -1;
+                       return error("invalid argument to -M: %s", arg+2);
                options->detect_rename = DIFF_DETECT_RENAME;
        }
-       else if (!prefixcmp(arg, "-C") || !prefixcmp(arg, "--detect-copies=") ||
-                !strcmp(arg, "--detect-copies")) {
+       else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
+               options->irreversible_delete = 1;
+       }
+       else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
+                !strcmp(arg, "--find-copies")) {
                if (options->detect_rename == DIFF_DETECT_COPY)
                        DIFF_OPT_SET(options, FIND_COPIES_HARDER);
                if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
-                       return -1;
+                       return error("invalid argument to -C: %s", arg+2);
                options->detect_rename = DIFF_DETECT_COPY;
        }
        else if (!strcmp(arg, "--no-renames"))
                options->detect_rename = 0;
+       else if (!strcmp(arg, "--rename-empty"))
+               DIFF_OPT_SET(options, RENAME_EMPTY);
+       else if (!strcmp(arg, "--no-rename-empty"))
+               DIFF_OPT_CLR(options, RENAME_EMPTY);
        else if (!strcmp(arg, "--relative"))
                DIFF_OPT_SET(options, RELATIVE_NAME);
-       else if (!prefixcmp(arg, "--relative=")) {
+       else if (skip_prefix(arg, "--relative=", &arg)) {
                DIFF_OPT_SET(options, RELATIVE_NAME);
-               options->prefix = arg + 11;
+               options->prefix = arg;
        }
 
        /* xdiff options */
+       else if (!strcmp(arg, "--minimal"))
+               DIFF_XDL_SET(options, NEED_MINIMAL);
+       else if (!strcmp(arg, "--no-minimal"))
+               DIFF_XDL_CLR(options, NEED_MINIMAL);
        else if (!strcmp(arg, "-w") || !strcmp(arg, "--ignore-all-space"))
                DIFF_XDL_SET(options, IGNORE_WHITESPACE);
        else if (!strcmp(arg, "-b") || !strcmp(arg, "--ignore-space-change"))
                DIFF_XDL_SET(options, IGNORE_WHITESPACE_CHANGE);
        else if (!strcmp(arg, "--ignore-space-at-eol"))
                DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
+       else if (!strcmp(arg, "--ignore-blank-lines"))
+               DIFF_XDL_SET(options, IGNORE_BLANK_LINES);
        else if (!strcmp(arg, "--patience"))
-               DIFF_XDL_SET(options, PATIENCE_DIFF);
+               options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
+       else if (!strcmp(arg, "--histogram"))
+               options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
+       else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
+               long value = parse_algorithm_value(optarg);
+               if (value < 0)
+                       return error("option diff-algorithm accepts \"myers\", "
+                                    "\"minimal\", \"patience\" and \"histogram\"");
+               /* clear out previous settings */
+               DIFF_XDL_CLR(options, NEED_MINIMAL);
+               options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
+               options->xdl_opts |= value;
+               return argcount;
+       }
 
        /* flags options */
        else if (!strcmp(arg, "--binary")) {
-               options->output_format |= DIFF_FORMAT_PATCH;
+               enable_patch_output(&options->output_format);
                DIFF_OPT_SET(options, BINARY);
        }
        else if (!strcmp(arg, "--full-index"))
@@ -3198,46 +3717,44 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                DIFF_OPT_SET(options, FIND_COPIES_HARDER);
        else if (!strcmp(arg, "--follow"))
                DIFF_OPT_SET(options, FOLLOW_RENAMES);
+       else if (!strcmp(arg, "--no-follow"))
+               DIFF_OPT_CLR(options, FOLLOW_RENAMES);
        else if (!strcmp(arg, "--color"))
-               DIFF_OPT_SET(options, COLOR_DIFF);
-       else if (!prefixcmp(arg, "--color=")) {
-               int value = git_config_colorbool(NULL, arg+8, -1);
-               if (value == 0)
-                       DIFF_OPT_CLR(options, COLOR_DIFF);
-               else if (value > 0)
-                       DIFF_OPT_SET(options, COLOR_DIFF);
-               else
+               options->use_color = 1;
+       else if (skip_prefix(arg, "--color=", &arg)) {
+               int value = git_config_colorbool(NULL, arg);
+               if (value < 0)
                        return error("option `color' expects \"always\", \"auto\", or \"never\"");
+               options->use_color = value;
        }
        else if (!strcmp(arg, "--no-color"))
-               DIFF_OPT_CLR(options, COLOR_DIFF);
+               options->use_color = 0;
        else if (!strcmp(arg, "--color-words")) {
-               DIFF_OPT_SET(options, COLOR_DIFF);
+               options->use_color = 1;
                options->word_diff = DIFF_WORDS_COLOR;
        }
-       else if (!prefixcmp(arg, "--color-words=")) {
-               DIFF_OPT_SET(options, COLOR_DIFF);
+       else if (skip_prefix(arg, "--color-words=", &arg)) {
+               options->use_color = 1;
                options->word_diff = DIFF_WORDS_COLOR;
-               options->word_regex = arg + 14;
+               options->word_regex = arg;
        }
        else if (!strcmp(arg, "--word-diff")) {
                if (options->word_diff == DIFF_WORDS_NONE)
                        options->word_diff = DIFF_WORDS_PLAIN;
        }
-       else if (!prefixcmp(arg, "--word-diff=")) {
-               const char *type = arg + 12;
-               if (!strcmp(type, "plain"))
+       else if (skip_prefix(arg, "--word-diff=", &arg)) {
+               if (!strcmp(arg, "plain"))
                        options->word_diff = DIFF_WORDS_PLAIN;
-               else if (!strcmp(type, "color")) {
-                       DIFF_OPT_SET(options, COLOR_DIFF);
+               else if (!strcmp(arg, "color")) {
+                       options->use_color = 1;
                        options->word_diff = DIFF_WORDS_COLOR;
                }
-               else if (!strcmp(type, "porcelain"))
+               else if (!strcmp(arg, "porcelain"))
                        options->word_diff = DIFF_WORDS_PORCELAIN;
-               else if (!strcmp(type, "none"))
+               else if (!strcmp(arg, "none"))
                        options->word_diff = DIFF_WORDS_NONE;
                else
-                       die("bad --word-diff argument: %s", type);
+                       die("bad --word-diff argument: %s", arg);
        }
        else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
                if (options->word_diff == DIFF_WORDS_NONE)
@@ -3260,15 +3777,13 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        else if (!strcmp(arg, "--ignore-submodules")) {
                DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
                handle_ignore_submodules_arg(options, "all");
-       } else if (!prefixcmp(arg, "--ignore-submodules=")) {
+       } else if (skip_prefix(arg, "--ignore-submodules=", &arg)) {
                DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
-               handle_ignore_submodules_arg(options, arg + 20);
+               handle_ignore_submodules_arg(options, arg);
        } else if (!strcmp(arg, "--submodule"))
                DIFF_OPT_SET(options, SUBMODULE_LOG);
-       else if (!prefixcmp(arg, "--submodule=")) {
-               if (!strcmp(arg + 12, "log"))
-                       DIFF_OPT_SET(options, SUBMODULE_LOG);
-       }
+       else if (skip_prefix(arg, "--submodule=", &arg))
+               return parse_submodule_opt(options, arg);
 
        /* misc options */
        else if (!strcmp(arg, "-z"))
@@ -3295,13 +3810,16 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                return argcount;
        }
        else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
-               options->filter = optarg;
+               int offending = parse_diff_filter_opt(optarg, options);
+               if (offending)
+                       die("unknown change class '%c' in --diff-filter=%s",
+                           offending, optarg);
                return argcount;
        }
        else if (!strcmp(arg, "--abbrev"))
                options->abbrev = DEFAULT_ABBREV;
-       else if (!prefixcmp(arg, "--abbrev=")) {
-               options->abbrev = strtoul(arg + 9, NULL, 10);
+       else if (skip_prefix(arg, "--abbrev=", &arg)) {
+               options->abbrev = strtoul(arg, NULL, 10);
                if (options->abbrev < MINIMUM_ABBREV)
                        options->abbrev = MINIMUM_ABBREV;
                else if (40 < options->abbrev)
@@ -3320,6 +3838,12 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        else if (opt_arg(arg, '\0', "inter-hunk-context",
                         &options->interhunkcontext))
                ;
+       else if (!strcmp(arg, "-W"))
+               DIFF_OPT_SET(options, FUNCCONTEXT);
+       else if (!strcmp(arg, "--function-context"))
+               DIFF_OPT_SET(options, FUNCCONTEXT);
+       else if (!strcmp(arg, "--no-function-context"))
+               DIFF_OPT_CLR(options, FUNCCONTEXT);
        else if ((argcount = parse_long_opt("output", av, &optarg))) {
                options->file = fopen(optarg, "w");
                if (!options->file)
@@ -3376,22 +3900,19 @@ static int diff_scoreopt_parse(const char *opt)
        cmd = *opt++;
        if (cmd == '-') {
                /* convert the long-form arguments into short-form versions */
-               if (!prefixcmp(opt, "break-rewrites")) {
-                       opt += strlen("break-rewrites");
+               if (skip_prefix(opt, "break-rewrites", &opt)) {
                        if (*opt == 0 || *opt++ == '=')
                                cmd = 'B';
-               } else if (!prefixcmp(opt, "detect-copies")) {
-                       opt += strlen("detect-copies");
+               } else if (skip_prefix(opt, "find-copies", &opt)) {
                        if (*opt == 0 || *opt++ == '=')
                                cmd = 'C';
-               } else if (!prefixcmp(opt, "detect-renames")) {
-                       opt += strlen("detect-renames");
+               } else if (skip_prefix(opt, "find-renames", &opt)) {
                        if (*opt == 0 || *opt++ == '=')
                                cmd = 'M';
                }
        }
        if (cmd != 'M' && cmd != 'C' && cmd != 'B')
-               return -1; /* that is not a -M, -C nor -B option */
+               return -1; /* that is not a -M, -Cor -B option */
 
        opt1 = parse_rename_score(&opt);
        if (cmd != 'B')
@@ -3415,11 +3936,7 @@ struct diff_queue_struct diff_queued_diff;
 
 void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 {
-       if (queue->alloc <= queue->nr) {
-               queue->alloc = alloc_nr(queue->alloc);
-               queue->queue = xrealloc(queue->queue,
-                                       sizeof(dp) * queue->alloc);
-       }
+       ALLOC_GROW(queue->queue, queue->nr + 1, queue->alloc);
        queue->queue[queue->nr++] = dp;
 }
 
@@ -3469,12 +3986,8 @@ static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
 {
        int line_termination = opt->line_termination;
        int inter_name_termination = line_termination ? '\t' : '\0';
-       if (opt->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = opt->output_prefix(opt, opt->output_prefix_data);
-               fprintf(opt->file, "%s", msg->buf);
-       }
 
+       fprintf(opt->file, "%s", diff_line_prefix(opt));
        if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
                fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
                        diff_unique_abbrev(p->one->sha1, opt->abbrev));
@@ -3593,9 +4106,9 @@ void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
                DIFF_FILE_VALID(s) ? "valid" : "invalid",
                s->mode,
                s->sha1_valid ? sha1_to_hex(s->sha1) : "");
-       fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
+       fprintf(stderr, "queue[%d] %s size %lu\n",
                x, one ? one : "",
-               s->size, s->xfrm_flags);
+               s->size);
 }
 
 void diff_debug_filepair(const struct diff_filepair *p, int i)
@@ -3744,12 +4257,7 @@ static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_fil
 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
 {
        FILE *file = opt->file;
-       char *line_prefix = "";
-
-       if (opt->output_prefix) {
-               struct strbuf *buf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = buf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(opt);
 
        switch(p->status) {
        case DIFF_STATUS_DELETED:
@@ -3803,7 +4311,7 @@ static void patch_id_consume(void *priv, char *line, unsigned long len)
        int new_len;
 
        /* Ignore line numbers when computing the SHA1 of the patch */
-       if (!prefixcmp(line, "@@ -"))
+       if (starts_with(line, "@@ -"))
                return;
 
        new_len = remove_space(line, len);
@@ -3894,7 +4402,7 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
 
                xpp.flags = 0;
                xecfg.ctxlen = 3;
-               xecfg.flags = XDL_EMIT_FUNCNAMES;
+               xecfg.flags = 0;
                xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
                              &xpp, &xecfg);
        }
@@ -3943,11 +4451,34 @@ static int is_summary_empty(const struct diff_queue_struct *q)
        return 1;
 }
 
+static const char rename_limit_warning[] =
+"inexact rename detection was skipped due to too many files.";
+
+static const char degrade_cc_to_c_warning[] =
+"only found copies from modified paths due to too many files.";
+
+static const char rename_limit_advice[] =
+"you may want to set your %s variable to at least "
+"%d and retry the command.";
+
+void diff_warn_rename_limit(const char *varname, int needed, int degraded_cc)
+{
+       if (degraded_cc)
+               warning(degrade_cc_to_c_warning);
+       else if (needed)
+               warning(rename_limit_warning);
+       else
+               return;
+       if (0 < needed && needed < 32767)
+               warning(rename_limit_advice, varname, needed);
+}
+
 void diff_flush(struct diff_options *options)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
        int i, output_format = options->output_format;
        int separator = 0;
+       int dirstat_by_line = 0;
 
        /*
         * Order: raw, stat, summary, patch
@@ -3968,7 +4499,11 @@ void diff_flush(struct diff_options *options)
                separator++;
        }
 
-       if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT)) {
+       if (output_format & DIFF_FORMAT_DIRSTAT && DIFF_OPT_TST(options, DIRSTAT_BY_LINE))
+               dirstat_by_line = 1;
+
+       if (output_format & (DIFF_FORMAT_DIFFSTAT|DIFF_FORMAT_SHORTSTAT|DIFF_FORMAT_NUMSTAT) ||
+           dirstat_by_line) {
                struct diffstat_t diffstat;
 
                memset(&diffstat, 0, sizeof(struct diffstat_t));
@@ -3983,10 +4518,12 @@ void diff_flush(struct diff_options *options)
                        show_stats(&diffstat, options);
                if (output_format & DIFF_FORMAT_SHORTSTAT)
                        show_shortstats(&diffstat, options);
+               if (output_format & DIFF_FORMAT_DIRSTAT)
+                       show_dirstat_by_line(&diffstat, options);
                free_diffstat_info(&diffstat);
                separator++;
        }
-       if (output_format & DIFF_FORMAT_DIRSTAT)
+       if ((output_format & DIFF_FORMAT_DIRSTAT) && !dirstat_by_line)
                show_dirstat(options);
 
        if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
@@ -4001,7 +4538,7 @@ void diff_flush(struct diff_options *options)
            DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
                /*
                 * run diff_flush_patch for the exit status. setting
-                * options->file to /dev/null should be safe, becaue we
+                * options->file to /dev/null should be safe, because we
                 * aren't supposed to produce any output anyway.
                 */
                if (options->close_file)
@@ -4021,7 +4558,9 @@ void diff_flush(struct diff_options *options)
 
        if (output_format & DIFF_FORMAT_PATCH) {
                if (separator) {
-                       putc(options->line_termination, options->file);
+                       fprintf(options->file, "%s%c",
+                               diff_line_prefix(options),
+                               options->line_termination);
                        if (options->stat_sep) {
                                /* attach patch instead of inline */
                                fputs(options->stat_sep, options->file);
@@ -4059,27 +4598,32 @@ void diff_flush(struct diff_options *options)
        }
 }
 
-static void diffcore_apply_filter(const char *filter)
+static int match_filter(const struct diff_options *options, const struct diff_filepair *p)
+{
+       return (((p->status == DIFF_STATUS_MODIFIED) &&
+                ((p->score &&
+                  filter_bit_tst(DIFF_STATUS_FILTER_BROKEN, options)) ||
+                 (!p->score &&
+                  filter_bit_tst(DIFF_STATUS_MODIFIED, options)))) ||
+               ((p->status != DIFF_STATUS_MODIFIED) &&
+                filter_bit_tst(p->status, options)));
+}
+
+static void diffcore_apply_filter(struct diff_options *options)
 {
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
+
        DIFF_QUEUE_CLEAR(&outq);
 
-       if (!filter)
+       if (!options->filter)
                return;
 
-       if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
+       if (filter_bit_tst(DIFF_STATUS_FILTER_AON, options)) {
                int found;
                for (i = found = 0; !found && i < q->nr; i++) {
-                       struct diff_filepair *p = q->queue[i];
-                       if (((p->status == DIFF_STATUS_MODIFIED) &&
-                            ((p->score &&
-                              strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-                             (!p->score &&
-                              strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-                           ((p->status != DIFF_STATUS_MODIFIED) &&
-                            strchr(filter, p->status)))
+                       if (match_filter(options, q->queue[i]))
                                found++;
                }
                if (found)
@@ -4097,14 +4641,7 @@ static void diffcore_apply_filter(const char *filter)
                /* Only the matching ones */
                for (i = 0; i < q->nr; i++) {
                        struct diff_filepair *p = q->queue[i];
-
-                       if (((p->status == DIFF_STATUS_MODIFIED) &&
-                            ((p->score &&
-                              strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
-                             (!p->score &&
-                              strchr(filter, DIFF_STATUS_MODIFIED)))) ||
-                           ((p->status != DIFF_STATUS_MODIFIED) &&
-                            strchr(filter, p->status)))
+                       if (match_filter(options, p))
                                diff_q(&outq, p);
                        else
                                diff_free_filepair(p);
@@ -4127,6 +4664,38 @@ static int diff_filespec_is_identical(struct diff_filespec *one,
        return !memcmp(one->data, two->data, one->size);
 }
 
+static int diff_filespec_check_stat_unmatch(struct diff_filepair *p)
+{
+       if (p->done_skip_stat_unmatch)
+               return p->skip_stat_unmatch_result;
+
+       p->done_skip_stat_unmatch = 1;
+       p->skip_stat_unmatch_result = 0;
+       /*
+        * 1. Entries that come from stat info dirtiness
+        *    always have both sides (iow, not create/delete),
+        *    one side of the object name is unknown, with
+        *    the same mode and size.  Keep the ones that
+        *    do not match these criteria.  They have real
+        *    differences.
+        *
+        * 2. At this point, the file is known to be modified,
+        *    with the same mode and size, and the object
+        *    name of one side is unknown.  Need to inspect
+        *    the identical contents.
+        */
+       if (!DIFF_FILE_VALID(p->one) || /* (1) */
+           !DIFF_FILE_VALID(p->two) ||
+           (p->one->sha1_valid && p->two->sha1_valid) ||
+           (p->one->mode != p->two->mode) ||
+           diff_populate_filespec(p->one, 1) ||
+           diff_populate_filespec(p->two, 1) ||
+           (p->one->size != p->two->size) ||
+           !diff_filespec_is_identical(p->one, p->two)) /* (2) */
+               p->skip_stat_unmatch_result = 1;
+       return p->skip_stat_unmatch_result;
+}
+
 static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
 {
        int i;
@@ -4137,27 +4706,7 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
 
-               /*
-                * 1. Entries that come from stat info dirtiness
-                *    always have both sides (iow, not create/delete),
-                *    one side of the object name is unknown, with
-                *    the same mode and size.  Keep the ones that
-                *    do not match these criteria.  They have real
-                *    differences.
-                *
-                * 2. At this point, the file is known to be modified,
-                *    with the same mode and size, and the object
-                *    name of one side is unknown.  Need to inspect
-                *    the identical contents.
-                */
-               if (!DIFF_FILE_VALID(p->one) || /* (1) */
-                   !DIFF_FILE_VALID(p->two) ||
-                   (p->one->sha1_valid && p->two->sha1_valid) ||
-                   (p->one->mode != p->two->mode) ||
-                   diff_populate_filespec(p->one, 1) ||
-                   diff_populate_filespec(p->two, 1) ||
-                   (p->one->size != p->two->size) ||
-                   !diff_filespec_is_identical(p->one, p->two)) /* (2) */
+               if (diff_filespec_check_stat_unmatch(p))
                        diff_q(&outq, p);
                else {
                        /*
@@ -4193,6 +4742,7 @@ void diffcore_fix_diff_index(struct diff_options *options)
 
 void diffcore_std(struct diff_options *options)
 {
+       /* NOTE please keep the following in sync with diff_tree_combined() */
        if (options->skip_stat_unmatch)
                diffcore_skip_stat_unmatch(options);
        if (!options->found_follow) {
@@ -4211,7 +4761,7 @@ void diffcore_std(struct diff_options *options)
        if (!options->found_follow)
                /* See try_to_follow_renames() in tree-diff.c */
                diff_resolve_rename_copy();
-       diffcore_apply_filter(options->filter);
+       diffcore_apply_filter(options);
 
        if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
                DIFF_OPT_SET(options, HAS_CHANGES);
@@ -4224,6 +4774,10 @@ void diffcore_std(struct diff_options *options)
 int diff_result_code(struct diff_options *opt, int status)
 {
        int result = 0;
+
+       diff_warn_rename_limit("diff.renameLimit",
+                              opt->needed_rename_limit,
+                              opt->degraded_cc_to_c);
        if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
            !(opt->output_format & DIFF_FORMAT_CHECKDIFF))
                return status;
@@ -4236,6 +4790,13 @@ int diff_result_code(struct diff_options *opt, int status)
        return result;
 }
 
+int diff_can_quit_early(struct diff_options *opt)
+{
+       return (DIFF_OPT_TST(opt, QUICK) &&
+               !opt->filter &&
+               DIFF_OPT_TST(opt, HAS_CHANGES));
+}
+
 /*
  * Shall changes to this submodule be ignored?
  *
@@ -4257,6 +4818,7 @@ static int is_submodule_ignored(const char *path, struct diff_options *options)
 void diff_addremove(struct diff_options *options,
                    int addremove, unsigned mode,
                    const unsigned char *sha1,
+                   int sha1_valid,
                    const char *concatpath, unsigned dirty_submodule)
 {
        struct diff_filespec *one, *two;
@@ -4288,9 +4850,9 @@ void diff_addremove(struct diff_options *options,
        two = alloc_filespec(concatpath);
 
        if (addremove != '+')
-               fill_filespec(one, sha1, mode);
+               fill_filespec(one, sha1, sha1_valid, mode);
        if (addremove != '-') {
-               fill_filespec(two, sha1, mode);
+               fill_filespec(two, sha1, sha1_valid, mode);
                two->dirty_submodule = dirty_submodule;
        }
 
@@ -4303,10 +4865,12 @@ void diff_change(struct diff_options *options,
                 unsigned old_mode, unsigned new_mode,
                 const unsigned char *old_sha1,
                 const unsigned char *new_sha1,
+                int old_sha1_valid, int new_sha1_valid,
                 const char *concatpath,
                 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
 {
        struct diff_filespec *one, *two;
+       struct diff_filepair *p;
 
        if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
            is_submodule_ignored(concatpath, options))
@@ -4317,6 +4881,8 @@ void diff_change(struct diff_options *options,
                const unsigned char *tmp_c;
                tmp = old_mode; old_mode = new_mode; new_mode = tmp;
                tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
+               tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
+                       new_sha1_valid = tmp;
                tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
                        new_dirty_submodule = tmp;
        }
@@ -4327,30 +4893,36 @@ void diff_change(struct diff_options *options,
 
        one = alloc_filespec(concatpath);
        two = alloc_filespec(concatpath);
-       fill_filespec(one, old_sha1, old_mode);
-       fill_filespec(two, new_sha1, new_mode);
+       fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
+       fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
        one->dirty_submodule = old_dirty_submodule;
        two->dirty_submodule = new_dirty_submodule;
+       p = diff_queue(&diff_queued_diff, one, two);
 
-       diff_queue(&diff_queued_diff, one, two);
-       if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
-               DIFF_OPT_SET(options, HAS_CHANGES);
+       if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
+               return;
+
+       if (DIFF_OPT_TST(options, QUICK) && options->skip_stat_unmatch &&
+           !diff_filespec_check_stat_unmatch(p))
+               return;
+
+       DIFF_OPT_SET(options, HAS_CHANGES);
 }
 
-void diff_unmerge(struct diff_options *options,
-                 const char *path,
-                 unsigned mode, const unsigned char *sha1)
+struct diff_filepair *diff_unmerge(struct diff_options *options, const char *path)
 {
+       struct diff_filepair *pair;
        struct diff_filespec *one, *two;
 
        if (options->prefix &&
            strncmp(path, options->prefix, options->prefix_length))
-               return;
+               return NULL;
 
        one = alloc_filespec(path);
        two = alloc_filespec(path);
-       fill_filespec(one, sha1, mode);
-       diff_queue(&diff_queued_diff, one, two)->is_unmerged = 1;
+       pair = diff_queue(&diff_queued_diff, one, two);
+       pair->is_unmerged = 1;
+       return pair;
 }
 
 static char *run_textconv(const char *pgm, struct diff_filespec *spec,
@@ -4408,7 +4980,7 @@ size_t fill_textconv(struct userdiff_driver *driver,
                return df->size;
        }
 
-       if (driver->textconv_cache) {
+       if (driver->textconv_cache && df->sha1_valid) {
                *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
                                          &size);
                if (*outbuf)
@@ -4419,7 +4991,7 @@ size_t fill_textconv(struct userdiff_driver *driver,
        if (!*outbuf)
                die("unable to read files to diff");
 
-       if (driver->textconv_cache) {
+       if (driver->textconv_cache && df->sha1_valid) {
                /* ignore errors, as we might be in a readonly repository */
                notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
                                size);
@@ -4434,3 +5006,19 @@ size_t fill_textconv(struct userdiff_driver *driver,
 
        return size;
 }
+
+void setup_diff_pager(struct diff_options *opt)
+{
+       /*
+        * If the user asked for our exit code, then either they want --quiet
+        * or --exit-code. We should definitely not bother with a pager in the
+        * former case, as we will generate no output. Since we still properly
+        * report our exit code even when a pager is run, we _could_ run a
+        * pager with --exit-code. But since we have not done so historically,
+        * and because it is easy to find people oneline advising "git diff
+        * --exit-code" in hooks and other scripts, we do not do so.
+        */
+       if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
+           check_pager_config("diff") != 0)
+               setup_pager();
+}