git-remote-ext
[gitweb.git] / diff.c
diff --git a/diff.c b/diff.c
index 8d8405aba29a4240f6a68c5fb1e3f0ad15050318..9a5c77c13ff3406a85e8a94f309a639529f2d88b 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -13,6 +13,8 @@
 #include "utf8.h"
 #include "userdiff.h"
 #include "sigchain.h"
+#include "submodule.h"
+#include "ll-merge.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
@@ -28,6 +30,8 @@ static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
+static int diff_no_prefix;
+static struct diff_options default_diff_options;
 
 static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
@@ -38,11 +42,9 @@ static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_GREEN,        /* NEW */
        GIT_COLOR_YELLOW,       /* COMMIT */
        GIT_COLOR_BG_RED,       /* WHITESPACE */
+       GIT_COLOR_NORMAL,       /* FUNCINFO */
 };
 
-static void diff_filespec_load_driver(struct diff_filespec *one);
-static char *run_textconv(const char *, struct diff_filespec *, size_t *);
-
 static int parse_diff_color_slot(const char *var, int ofs)
 {
        if (!strcasecmp(var+ofs, "plain"))
@@ -59,6 +61,8 @@ static int parse_diff_color_slot(const char *var, int ofs)
                return DIFF_COMMIT;
        if (!strcasecmp(var+ofs, "whitespace"))
                return DIFF_WHITESPACE;
+       if (!strcasecmp(var+ofs, "func"))
+               return DIFF_FUNCINFO;
        return -1;
 }
 
@@ -95,11 +99,18 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
                diff_mnemonic_prefix = git_config_bool(var, value);
                return 0;
        }
+       if (!strcmp(var, "diff.noprefix")) {
+               diff_no_prefix = git_config_bool(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.ignoresubmodules"))
+               handle_ignore_submodules_arg(&default_diff_options, value);
+
        return git_diff_basic_config(var, value, cb);
 }
 
@@ -134,6 +145,9 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
                return 0;
        }
 
+       if (!prefixcmp(var, "submodule."))
+               return parse_submodule_config_option(var, value);
+
        return git_color_default_config(var, value, cb);
 }
 
@@ -188,8 +202,9 @@ struct emit_callback {
        sane_truncate_fn truncate;
        const char **label_path;
        struct diff_words_data *diff_words;
+       struct diff_options *opt;
        int *found_changesp;
-       FILE *file;
+       struct strbuf *header;
 };
 
 static int count_lines(const char *data, int size)
@@ -275,11 +290,19 @@ static void check_blank_at_eof(mmfile_t *mf1, mmfile_t *mf2,
        ecbdata->blank_at_eof_in_postimage = (at - l2) + 1;
 }
 
-static void emit_line_0(FILE *file, const char *set, const char *reset,
+static void emit_line_0(struct diff_options *o, const char *set, const char *reset,
                        int first, const char *line, int len)
 {
        int has_trailing_newline, has_trailing_carriage_return;
        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);
+       }
 
        if (len == 0) {
                has_trailing_newline = (first == '\n');
@@ -296,22 +319,23 @@ static void emit_line_0(FILE *file, const char *set, const char *reset,
                nofirst = 0;
        }
 
-       fputs(set, file);
-
-       if (!nofirst)
-               fputc(first, file);
-       fwrite(line, len, 1, file);
-       fputs(reset, file);
+       if (len || !nofirst) {
+               fputs(set, file);
+               if (!nofirst)
+                       fputc(first, file);
+               fwrite(line, len, 1, file);
+               fputs(reset, file);
+       }
        if (has_trailing_carriage_return)
                fputc('\r', file);
        if (has_trailing_newline)
                fputc('\n', file);
 }
 
-static void emit_line(FILE *file, const char *set, const char *reset,
+static void emit_line(struct diff_options *o, const char *set, const char *reset,
                      const char *line, int len)
 {
-       emit_line_0(file, set, reset, line[0], line+1, len-1);
+       emit_line_0(o, set, reset, line[0], line+1, len-1);
 }
 
 static int new_blank_line_at_eof(struct emit_callback *ecbdata, const char *line, int len)
@@ -333,18 +357,76 @@ static void emit_add_line(const char *reset,
        const char *set = diff_get_color(ecbdata->color_diff, DIFF_FILE_NEW);
 
        if (!*ws)
-               emit_line_0(ecbdata->file, set, reset, '+', line, len);
+               emit_line_0(ecbdata->opt, set, reset, '+', line, len);
        else if (new_blank_line_at_eof(ecbdata, line, len))
                /* Blank line at EOF - paint '+' as well */
-               emit_line_0(ecbdata->file, ws, reset, '+', line, len);
+               emit_line_0(ecbdata->opt, ws, reset, '+', line, len);
        else {
                /* Emit just the prefix, then the rest. */
-               emit_line_0(ecbdata->file, set, reset, '+', "", 0);
+               emit_line_0(ecbdata->opt, set, reset, '+', "", 0);
                ws_check_emit(line, len, ecbdata->ws_rule,
-                             ecbdata->file, set, reset, ws);
+                             ecbdata->opt->file, set, reset, ws);
        }
 }
 
+static void emit_hunk_header(struct emit_callback *ecbdata,
+                            const char *line, int len)
+{
+       const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
+       const char *frag = diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO);
+       const char *func = diff_get_color(ecbdata->color_diff, DIFF_FUNCINFO);
+       const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
+       static const char atat[2] = { '@', '@' };
+       const char *cp, *ep;
+       struct strbuf msgbuf = STRBUF_INIT;
+       int org_len = len;
+       int i = 1;
+
+       /*
+        * As a hunk header must begin with "@@ -<old>, +<new> @@",
+        * it always is at least 10 bytes long.
+        */
+       if (len < 10 ||
+           memcmp(line, atat, 2) ||
+           !(ep = memmem(line + 2, len - 2, atat, 2))) {
+               emit_line(ecbdata->opt, plain, reset, line, len);
+               return;
+       }
+       ep += 2; /* skip over @@ */
+
+       /* The hunk header in fraginfo color */
+       strbuf_add(&msgbuf, frag, strlen(frag));
+       strbuf_add(&msgbuf, line, ep - line);
+       strbuf_add(&msgbuf, reset, strlen(reset));
+
+       /*
+        * trailing "\r\n"
+        */
+       for ( ; i < 3; i++)
+               if (line[len - i] == '\r' || line[len - i] == '\n')
+                       len--;
+
+       /* blank before the func header */
+       for (cp = ep; ep - line < len; ep++)
+               if (*ep != ' ' && *ep != '\t')
+                       break;
+       if (ep != cp) {
+               strbuf_add(&msgbuf, plain, strlen(plain));
+               strbuf_add(&msgbuf, cp, ep - cp);
+               strbuf_add(&msgbuf, reset, strlen(reset));
+       }
+
+       if (ep < line + len) {
+               strbuf_add(&msgbuf, func, strlen(func));
+               strbuf_add(&msgbuf, ep, line + len - ep);
+               strbuf_add(&msgbuf, reset, strlen(reset));
+       }
+
+       strbuf_add(&msgbuf, line + len, org_len - len);
+       emit_line(ecbdata->opt, "", "", msgbuf.buf, msgbuf.len);
+       strbuf_release(&msgbuf);
+}
+
 static struct diff_tempfile *claim_diff_tempfile(void) {
        int i;
        for (i = 0; i < ARRAY_SIZE(diff_temp); i++)
@@ -402,7 +484,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
                len = endp ? (endp - data + 1) : size;
                if (prefix != '+') {
                        ecb->lno_in_preimage++;
-                       emit_line_0(ecb->file, old, reset, '-',
+                       emit_line_0(ecb->opt, old, reset, '-',
                                    data, len);
                } else {
                        ecb->lno_in_postimage++;
@@ -414,7 +496,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
        if (!endp) {
                const char *plain = diff_get_color(ecb->color_diff,
                                                   DIFF_PLAIN);
-               emit_line_0(ecb->file, plain, reset, '\\',
+               emit_line_0(ecb->opt, plain, reset, '\\',
                            nneof, strlen(nneof));
        }
 }
@@ -423,8 +505,8 @@ static void emit_rewrite_diff(const char *name_a,
                              const char *name_b,
                              struct diff_filespec *one,
                              struct diff_filespec *two,
-                             const char *textconv_one,
-                             const char *textconv_two,
+                             struct userdiff_driver *textconv_one,
+                             struct userdiff_driver *textconv_two,
                              struct diff_options *o)
 {
        int lc_a, lc_b;
@@ -435,9 +517,16 @@ static void emit_rewrite_diff(const char *name_a,
        const char *reset = diff_get_color(color_diff, DIFF_RESET);
        static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
        const char *a_prefix, *b_prefix;
-       const char *data_one, *data_two;
+       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;
+       }
 
        if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
                a_prefix = o->b_prefix;
@@ -457,32 +546,14 @@ static void emit_rewrite_diff(const char *name_a,
        quote_two_c_style(&a_name, a_prefix, name_a, 0);
        quote_two_c_style(&b_name, b_prefix, name_b, 0);
 
-       diff_populate_filespec(one, 0);
-       diff_populate_filespec(two, 0);
-       if (textconv_one) {
-               data_one = run_textconv(textconv_one, one, &size_one);
-               if (!data_one)
-                       die("unable to read files to diff");
-       }
-       else {
-               data_one = one->data;
-               size_one = one->size;
-       }
-       if (textconv_two) {
-               data_two = run_textconv(textconv_two, two, &size_two);
-               if (!data_two)
-                       die("unable to read files to diff");
-       }
-       else {
-               data_two = two->data;
-               size_two = two->size;
-       }
+       size_one = fill_textconv(textconv_one, one, &data_one);
+       size_two = fill_textconv(textconv_two, two, &data_two);
 
        memset(&ecbdata, 0, sizeof(ecbdata));
        ecbdata.color_diff = color_diff;
        ecbdata.found_changesp = &o->found_changes;
        ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
-       ecbdata.file = o->file;
+       ecbdata.opt = o;
        if (ecbdata.ws_rule & WS_BLANK_AT_EOF) {
                mmfile_t mf1, mf2;
                mf1.ptr = (char *)data_one;
@@ -497,9 +568,10 @@ static void emit_rewrite_diff(const char *name_a,
        lc_a = count_lines(data_one, size_one);
        lc_b = count_lines(data_two, size_two);
        fprintf(o->file,
-               "%s--- %s%s%s\n%s+++ %s%s%s\n%s@@ -",
-               metainfo, a_name.buf, name_a_tab, reset,
-               metainfo, b_name.buf, name_b_tab, reset, fraginfo);
+               "%s%s--- %s%s%s\n%s%s+++ %s%s%s\n%s%s@@ -",
+               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);
        fprintf(o->file, " +");
        print_line_count(o->file, lc_b);
@@ -508,6 +580,10 @@ static void emit_rewrite_diff(const char *name_a,
                emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
        if (lc_b)
                emit_rewrite_lines(&ecbdata, '+', data_two, size_two);
+       if (textconv_one)
+               free((char *)data_one);
+       if (textconv_two)
+               free((char *)data_two);
 }
 
 struct diff_words_buffer {
@@ -530,23 +606,134 @@ static void diff_words_append(char *line, unsigned long len,
        buffer->text.ptr[buffer->text.size] = '\0';
 }
 
+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
+{
+       enum diff_words_type type;
+       struct diff_words_style_elem new, old, ctx;
+       const char *newline;
+};
+
+struct diff_words_style diff_words_styles[] = {
+       { DIFF_WORDS_PORCELAIN, {"+", "\n"}, {"-", "\n"}, {" ", "\n"}, "~\n" },
+       { DIFF_WORDS_PLAIN, {"{+", "+}"}, {"[-", "-]"}, {"", ""}, "\n" },
+       { DIFF_WORDS_COLOR, {"", ""}, {"", ""}, {"", ""}, "\n" }
+};
+
 struct diff_words_data {
        struct diff_words_buffer minus, plus;
        const char *current_plus;
-       FILE *file;
+       int last_minus;
+       struct diff_options *opt;
        regex_t *word_regex;
+       enum diff_words_type type;
+       struct diff_words_style *style;
 };
 
+static int fn_out_diff_words_write_helper(FILE *fp,
+                                         struct diff_words_style_elem *st_el,
+                                         const char *newline,
+                                         size_t count, const char *buf,
+                                         const char *line_prefix)
+{
+       int print = 0;
+
+       while (count) {
+               char *p = memchr(buf, '\n', count);
+               if (print)
+                       fputs(line_prefix, fp);
+               if (p != buf) {
+                       if (st_el->color && fputs(st_el->color, fp) < 0)
+                               return -1;
+                       if (fputs(st_el->prefix, fp) < 0 ||
+                           fwrite(buf, p ? p - buf : count, 1, fp) != 1 ||
+                           fputs(st_el->suffix, fp) < 0)
+                               return -1;
+                       if (st_el->color && *st_el->color
+                           && fputs(GIT_COLOR_RESET, fp) < 0)
+                               return -1;
+               }
+               if (!p)
+                       return 0;
+               if (fputs(newline, fp) < 0)
+                       return -1;
+               count -= p + 1 - buf;
+               buf = p + 1;
+               print = 1;
+       }
+       return 0;
+}
+
+/*
+ * '--color-words' algorithm can be described as:
+ *
+ *   1. collect a the minus/plus lines of a diff hunk, divided into
+ *      minus-lines and plus-lines;
+ *
+ *   2. break both minus-lines and plus-lines into words and
+ *      place them into two mmfile_t with one word for each line;
+ *
+ *   3. use xdiff to run diff on the two mmfile_t to get the words level diff;
+ *
+ * And for the common parts of the both file, we output the plus side text.
+ * diff_words->current_plus is used to trace the current position of the plus file
+ * which printed. diff_words->last_minus is used to trace the last minus word
+ * printed.
+ *
+ * For '--graph' to work with '--color-words', we need to output the graph prefix
+ * on each line of color words output. Generally, there are two conditions on
+ * which we should output the prefix.
+ *
+ *   1. diff_words->last_minus == 0 &&
+ *      diff_words->current_plus == diff_words->plus.text.ptr
+ *
+ *      that is: the plus text must start as a new line, and if there is no minus
+ *      word printed, a graph prefix must be printed.
+ *
+ *   2. diff_words->current_plus > diff_words->plus.text.ptr &&
+ *      *(diff_words->current_plus - 1) == '\n'
+ *
+ *      that is: a graph prefix must be printed following a '\n'
+ */
+static int color_words_output_graph_prefix(struct diff_words_data *diff_words)
+{
+       if ((diff_words->last_minus == 0 &&
+               diff_words->current_plus == diff_words->plus.text.ptr) ||
+               (diff_words->current_plus > diff_words->plus.text.ptr &&
+               *(diff_words->current_plus - 1) == '\n')) {
+               return 1;
+       } else {
+               return 0;
+       }
+}
+
 static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
 {
        struct diff_words_data *diff_words = priv;
+       struct diff_words_style *style = diff_words->style;
        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 = "";
 
        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;
+       }
+
        /* POSIX requires that first be decremented by one if len == 0... */
        if (minus_len) {
                minus_begin = diff_words->minus.orig[minus_first].begin;
@@ -562,20 +749,32 @@ static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
        } else
                plus_begin = plus_end = diff_words->plus.orig[plus_first].end;
 
-       if (diff_words->current_plus != plus_begin)
-               fwrite(diff_words->current_plus,
-                               plus_begin - diff_words->current_plus, 1,
-                               diff_words->file);
-       if (minus_begin != minus_end)
-               color_fwrite_lines(diff_words->file,
-                               diff_get_color(1, DIFF_FILE_OLD),
-                               minus_end - minus_begin, minus_begin);
-       if (plus_begin != plus_end)
-               color_fwrite_lines(diff_words->file,
-                               diff_get_color(1, DIFF_FILE_NEW),
-                               plus_end - plus_begin, plus_begin);
+       if (color_words_output_graph_prefix(diff_words)) {
+               fputs(line_prefix, diff_words->opt->file);
+       }
+       if (diff_words->current_plus != plus_begin) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->ctx, style->newline,
+                               plus_begin - diff_words->current_plus,
+                               diff_words->current_plus, line_prefix);
+               if (*(plus_begin - 1) == '\n')
+                       fputs(line_prefix, diff_words->opt->file);
+       }
+       if (minus_begin != minus_end) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->old, style->newline,
+                               minus_end - minus_begin, minus_begin,
+                               line_prefix);
+       }
+       if (plus_begin != plus_end) {
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                               &style->new, style->newline,
+                               plus_end - plus_begin, plus_begin,
+                               line_prefix);
+       }
 
        diff_words->current_plus = plus_end;
+       diff_words->last_minus = minus_first;
 }
 
 /* This function starts looking at *begin, and returns 0 iff a word was found. */
@@ -653,37 +852,54 @@ static void diff_words_show(struct diff_words_data *diff_words)
 {
        xpparam_t xpp;
        xdemitconf_t xecfg;
-       xdemitcb_t ecb;
        mmfile_t minus, plus;
+       struct diff_words_style *style = diff_words->style;
+
+       struct diff_options *opt = diff_words->opt;
+       struct strbuf *msgbuf;
+       char *line_prefix = "";
+
+       assert(opt);
+       if (opt->output_prefix) {
+               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        /* special case: only removal */
        if (!diff_words->plus.text.size) {
-               color_fwrite_lines(diff_words->file,
-                       diff_get_color(1, DIFF_FILE_OLD),
-                       diff_words->minus.text.size, diff_words->minus.text.ptr);
+               fputs(line_prefix, diff_words->opt->file);
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                       &style->old, style->newline,
+                       diff_words->minus.text.size,
+                       diff_words->minus.text.ptr, line_prefix);
                diff_words->minus.text.size = 0;
                return;
        }
 
        diff_words->current_plus = diff_words->plus.text.ptr;
+       diff_words->last_minus = 0;
 
        memset(&xpp, 0, sizeof(xpp));
        memset(&xecfg, 0, sizeof(xecfg));
        diff_words_fill(&diff_words->minus, &minus, diff_words->word_regex);
        diff_words_fill(&diff_words->plus, &plus, diff_words->word_regex);
-       xpp.flags = XDF_NEED_MINIMAL;
+       xpp.flags = 0;
        /* as only the hunk header will be parsed, we need a 0-context */
        xecfg.ctxlen = 0;
        xdi_diff_outf(&minus, &plus, fn_out_diff_words_aux, diff_words,
-                     &xpp, &xecfg, &ecb);
+                     &xpp, &xecfg);
        free(minus.ptr);
        free(plus.ptr);
        if (diff_words->current_plus != diff_words->plus.text.ptr +
-                       diff_words->plus.text.size)
-               fwrite(diff_words->current_plus,
+                       diff_words->plus.text.size) {
+               if (color_words_output_graph_prefix(diff_words))
+                       fputs(line_prefix, diff_words->opt->file);
+               fn_out_diff_words_write_helper(diff_words->opt->file,
+                       &style->ctx, style->newline,
                        diff_words->plus.text.ptr + diff_words->plus.text.size
-                       - diff_words->current_plus, 1,
-                       diff_words->file);
+                       - diff_words->current_plus, diff_words->current_plus,
+                       line_prefix);
+       }
        diff_words->minus.text.size = diff_words->plus.text.size = 0;
 }
 
@@ -703,7 +919,10 @@ static void free_diff_words_data(struct emit_callback *ecbdata)
                free (ecbdata->diff_words->minus.orig);
                free (ecbdata->diff_words->plus.text.ptr);
                free (ecbdata->diff_words->plus.orig);
-               free(ecbdata->diff_words->word_regex);
+               if (ecbdata->diff_words->word_regex) {
+                       regfree(ecbdata->diff_words->word_regex);
+                       free(ecbdata->diff_words->word_regex);
+               }
                free(ecbdata->diff_words);
                ecbdata->diff_words = NULL;
        }
@@ -755,7 +974,20 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        const char *meta = diff_get_color(ecbdata->color_diff, DIFF_METAINFO);
        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;
+       }
 
+       if (ecbdata->header) {
+               fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
+               strbuf_reset(ecbdata->header);
+               ecbdata->header = NULL;
+       }
        *(ecbdata->found_changesp) = 1;
 
        if (ecbdata->label_path[0]) {
@@ -764,10 +996,10 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                name_a_tab = strchr(ecbdata->label_path[0], ' ') ? "\t" : "";
                name_b_tab = strchr(ecbdata->label_path[1], ' ') ? "\t" : "";
 
-               fprintf(ecbdata->file, "%s--- %s%s%s\n",
-                       meta, ecbdata->label_path[0], reset, name_a_tab);
-               fprintf(ecbdata->file, "%s+++ %s%s%s\n",
-                       meta, ecbdata->label_path[1], reset, name_b_tab);
+               fprintf(ecbdata->opt->file, "%s%s--- %s%s%s\n",
+                       line_prefix, meta, ecbdata->label_path[0], reset, name_a_tab);
+               fprintf(ecbdata->opt->file, "%s%s+++ %s%s%s\n",
+                       line_prefix, meta, ecbdata->label_path[1], reset, name_b_tab);
                ecbdata->label_path[0] = ecbdata->label_path[1] = NULL;
        }
 
@@ -782,16 +1014,17 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                        diff_words_flush(ecbdata);
                len = sane_truncate_line(ecbdata, line, len);
                find_lno(line, ecbdata);
-               emit_line(ecbdata->file,
-                         diff_get_color(ecbdata->color_diff, DIFF_FRAGINFO),
-                         reset, line, len);
+               emit_hunk_header(ecbdata, line, len);
                if (line[len-1] != '\n')
-                       putc('\n', ecbdata->file);
+                       putc('\n', ecbdata->opt->file);
                return;
        }
 
        if (len < 1) {
-               emit_line(ecbdata->file, reset, reset, line, len);
+               emit_line(ecbdata->opt, reset, reset, line, len);
+               if (ecbdata->diff_words
+                   && ecbdata->diff_words->type == DIFF_WORDS_PORCELAIN)
+                       fputs("~\n", ecbdata->opt->file);
                return;
        }
 
@@ -806,9 +1039,13 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                        return;
                }
                diff_words_flush(ecbdata);
-               line++;
-               len--;
-               emit_line(ecbdata->file, plain, reset, line, len);
+               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);
+               }
                return;
        }
 
@@ -819,7 +1056,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
                ecbdata->lno_in_preimage++;
                if (line[0] == ' ')
                        ecbdata->lno_in_postimage++;
-               emit_line(ecbdata->file, color, reset, line, len);
+               emit_line(ecbdata->opt, color, reset, line, len);
        } else {
                ecbdata->lno_in_postimage++;
                emit_add_line(reset, ecbdata, line + 1, len - 1);
@@ -903,7 +1140,7 @@ struct diffstat_t {
                unsigned is_unmerged:1;
                unsigned is_binary:1;
                unsigned is_renamed:1;
-               unsigned int added, deleted;
+               uintmax_t added, deleted;
        } **files;
 };
 
@@ -995,14 +1232,21 @@ static void fill_print_name(struct diffstat_file *file)
 static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
        int i, len, add, del, adds = 0, dels = 0;
-       int max_change = 0, max_len = 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;
+       const char *line_prefix = "";
+       struct strbuf *msg = NULL;
 
        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;
 
@@ -1024,7 +1268,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 
        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
-               int change = file->added + file->deleted;
+               uintmax_t change = file->added + file->deleted;
                fill_print_name(file);
                len = strlen(file->print_name);
                if (max_len < len)
@@ -1052,8 +1296,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
        for (i = 0; i < data->nr; i++) {
                const char *prefix = "";
                char *name = data->files[i]->print_name;
-               int added = data->files[i]->added;
-               int deleted = data->files[i]->deleted;
+               uintmax_t added = data->files[i]->added;
+               uintmax_t deleted = data->files[i]->deleted;
                int name_len;
 
                /*
@@ -1072,16 +1316,20 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                }
 
                if (data->files[i]->is_binary) {
+                       fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, "  Bin ");
-                       fprintf(options->file, "%s%d%s", del_c, deleted, reset);
+                       fprintf(options->file, "%s%"PRIuMAX"%s",
+                               del_c, deleted, reset);
                        fprintf(options->file, " -> ");
-                       fprintf(options->file, "%s%d%s", add_c, added, reset);
+                       fprintf(options->file, "%s%"PRIuMAX"%s",
+                               add_c, added, reset);
                        fprintf(options->file, " bytes");
                        fprintf(options->file, "\n");
                        continue;
                }
                else if (data->files[i]->is_unmerged) {
+                       fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, "  Unmerged\n");
                        continue;
@@ -1104,19 +1352,21 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                        add = scale_linear(add, width, max_change);
                        del = scale_linear(del, width, max_change);
                }
+               fprintf(options->file, "%s", line_prefix);
                show_name(options->file, prefix, name, len);
-               fprintf(options->file, "%5d%s", added + deleted,
+               fprintf(options->file, "%5"PRIuMAX"%s", added + deleted,
                                added + deleted ? " " : "");
                show_graph(options->file, '+', add, add_c, reset);
                show_graph(options->file, '-', del, del_c, reset);
                fprintf(options->file, "\n");
        }
+       fprintf(options->file, "%s", line_prefix);
        fprintf(options->file,
               " %d files changed, %d insertions(+), %d deletions(-)\n",
               total_files, adds, dels);
 }
 
-static void show_shortstats(struct diffstat_tdata, struct diff_options *options)
+static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
 {
        int i, adds = 0, dels = 0, total_files = data->nr;
 
@@ -1137,6 +1387,12 @@ static void show_shortstats(struct diffstat_t* data, struct diff_options *option
                        }
                }
        }
+       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);
 }
@@ -1151,11 +1407,19 @@ 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);
+               }
+
                if (file->is_binary)
                        fprintf(options->file, "-\t-\t");
                else
                        fprintf(options->file,
-                               "%d\t%d\t", file->added, file->deleted);
+                               "%"PRIuMAX"\t%"PRIuMAX"\t",
+                               file->added, file->deleted);
                if (options->line_termination) {
                        fill_print_name(file);
                        if (!file->is_renamed)
@@ -1185,10 +1449,18 @@ struct dirstat_dir {
        int alloc, nr, percent, cumulative;
 };
 
-static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long changed, const char *base, int baselen)
+static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
+               unsigned long changed, const char *base, int baselen)
 {
        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;
+       }
 
        while (dir->nr) {
                struct dirstat_file *f = dir->files;
@@ -1203,7 +1475,7 @@ static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long ch
                slash = strchr(f->name + baselen, '/');
                if (slash) {
                        int newbaselen = slash + 1 - f->name;
-                       this = gather_dirstat(file, dir, changed, f->name, newbaselen);
+                       this = gather_dirstat(opt, dir, changed, f->name, newbaselen);
                        sources++;
                } else {
                        this = f->changed;
@@ -1225,7 +1497,8 @@ static long gather_dirstat(FILE *file, struct dirstat_dir *dir, unsigned long ch
                if (permille) {
                        int percent = permille / 10;
                        if (percent >= dir->percent) {
-                               fprintf(file, "%4d.%01d%% %.*s\n", percent, permille % 10, baselen, base);
+                               fprintf(opt->file, "%s%4d.%01d%% %.*s\n", line_prefix,
+                                       percent, permille % 10, baselen, base);
                                if (!dir->cumulative)
                                        return 0;
                        }
@@ -1305,7 +1578,7 @@ static void show_dirstat(struct diff_options *options)
 
        /* Show all directories with more than x% of the changes */
        qsort(dir.files, dir.nr, sizeof(dir.files[0]), dirstat_compare);
-       gather_dirstat(options->file, &dir, changed, "", 0);
+       gather_dirstat(options, &dir, changed, "", 0);
 }
 
 static void free_diffstat_info(struct diffstat_t *diffstat)
@@ -1325,37 +1598,32 @@ static void free_diffstat_info(struct diffstat_t *diffstat)
 struct checkdiff_t {
        const char *filename;
        int lineno;
+       int conflict_marker_size;
        struct diff_options *o;
        unsigned ws_rule;
        unsigned status;
 };
 
-static int is_conflict_marker(const char *line, unsigned long len)
+static int is_conflict_marker(const char *line, int marker_size, unsigned long len)
 {
        char firstchar;
        int cnt;
 
-       if (len < 8)
+       if (len < marker_size + 1)
                return 0;
        firstchar = line[0];
        switch (firstchar) {
-       case '=': case '>': case '<':
+       case '=': case '>': case '<': case '|':
                break;
        default:
                return 0;
        }
-       for (cnt = 1; cnt < 7; cnt++)
+       for (cnt = 1; cnt < marker_size; cnt++)
                if (line[cnt] != firstchar)
                        return 0;
-       /* line[0] thru line[6] are same as firstchar */
-       if (firstchar == '=') {
-               /* divider between ours and theirs? */
-               if (len != 8 || line[7] != '\n')
-                       return 0;
-       } else if (len < 8 || !isspace(line[7])) {
-               /* not divider before ours nor after theirs */
+       /* line[1] thru line[marker_size-1] are same as firstchar */
+       if (len < marker_size + 1 || !isspace(line[marker_size]))
                return 0;
-       }
        return 1;
 }
 
@@ -1363,29 +1631,39 @@ 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);
        char *err;
+       char *line_prefix = "";
+       struct strbuf *msgbuf;
+
+       assert(data->o);
+       if (data->o->output_prefix) {
+               msgbuf = data->o->output_prefix(data->o,
+                       data->o->output_prefix_data);
+               line_prefix = msgbuf->buf;
+       }
 
        if (line[0] == '+') {
                unsigned bad;
                data->lineno++;
-               if (is_conflict_marker(line + 1, len - 1)) {
+               if (is_conflict_marker(line + 1, marker_size, len - 1)) {
                        data->status |= 1;
                        fprintf(data->o->file,
-                               "%s:%d: leftover conflict marker\n",
-                               data->filename, data->lineno);
+                               "%s%s:%d: leftover conflict marker\n",
+                               line_prefix, data->filename, data->lineno);
                }
                bad = ws_check(line + 1, len - 1, data->ws_rule);
                if (!bad)
                        return;
                data->status |= bad;
                err = whitespace_error_string(bad);
-               fprintf(data->o->file, "%s:%d: %s.\n",
-                       data->filename, data->lineno, err);
+               fprintf(data->o->file, "%s%s:%d: %s.\n",
+                       line_prefix, data->filename, data->lineno, err);
                free(err);
-               emit_line(data->o->file, set, reset, line, 1);
+               emit_line(data->o, set, reset, line, 1);
                ws_check_emit(line + 1, len - 1, data->ws_rule,
                              data->o->file, set, reset, ws);
        } else if (line[0] == ' ') {
@@ -1423,7 +1701,7 @@ static unsigned char *deflate_it(char *data,
        return deflated;
 }
 
-static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
+static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
 {
        void *cp;
        void *delta;
@@ -1452,13 +1730,13 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
        }
 
        if (delta && delta_size < deflate_size) {
-               fprintf(file, "delta %lu\n", orig_size);
+               fprintf(file, "%sdelta %lu\n", prefix, orig_size);
                free(deflated);
                data = delta;
                data_size = delta_size;
        }
        else {
-               fprintf(file, "literal %lu\n", two->size);
+               fprintf(file, "%sliteral %lu\n", prefix, two->size);
                free(delta);
                data = deflated;
                data_size = deflate_size;
@@ -1476,18 +1754,19 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two)
                        line[0] = bytes - 26 + 'a' - 1;
                encode_85(line + 1, cp, bytes);
                cp = (char *) cp + bytes;
+               fprintf(file, "%s", prefix);
                fputs(line, file);
                fputc('\n', file);
        }
-       fprintf(file, "\n");
+       fprintf(file, "%s\n", prefix);
        free(data);
 }
 
-static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two)
+static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
 {
-       fprintf(file, "GIT binary patch\n");
-       emit_binary_diff_body(file, one, two);
-       emit_binary_diff_body(file, two, one);
+       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)
@@ -1537,14 +1816,26 @@ void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const
                options->b_prefix = b;
 }
 
-static const char *get_textconv(struct diff_filespec *one)
+struct userdiff_driver *get_textconv(struct diff_filespec *one)
 {
        if (!DIFF_FILE_VALID(one))
                return NULL;
        if (!S_ISREG(one->mode))
                return NULL;
        diff_filespec_load_driver(one);
-       return one->driver->textconv;
+       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;
 }
 
 static void builtin_diff(const char *name_a,
@@ -1552,6 +1843,7 @@ static void builtin_diff(const char *name_a,
                         struct diff_filespec *one,
                         struct diff_filespec *two,
                         const char *xfrm_msg,
+                        int must_show_header,
                         struct diff_options *o,
                         int complete_rewrite)
 {
@@ -1561,7 +1853,27 @@ static void builtin_diff(const char *name_a,
        const char *set = diff_get_color_opt(o, DIFF_METAINFO);
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
-       const char *textconv_one = NULL, *textconv_two = NULL;
+       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;
+       }
+
+       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,
+                               one->sha1, two->sha1, two->dirty_submodule,
+                               del, add, reset);
+               return;
+       }
 
        if (DIFF_OPT_TST(o, ALLOW_TEXTCONV)) {
                textconv_one = get_textconv(one);
@@ -1585,25 +1897,29 @@ 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";
-       fprintf(o->file, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
+       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, set, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
-               fprintf(o->file, "%snew file mode %06o%s\n", set, two->mode, reset);
-               if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, set, two->mode, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
+               must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
-               fprintf(o->file, "%sdeleted file mode %06o%s\n", set, one->mode, reset);
-               if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, set, one->mode, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
+               must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
-                       fprintf(o->file, "%sold mode %06o%s\n", set, one->mode, reset);
-                       fprintf(o->file, "%snew mode %06o%s\n", set, two->mode, reset);
+                       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);
+                       must_show_header = 1;
                }
-               if (xfrm_msg && xfrm_msg[0])
-                       fprintf(o->file, "%s%s%s\n", set, xfrm_msg, reset);
+               if (xfrm_msg)
+                       strbuf_addstr(&header, xfrm_msg);
+
                /*
                 * we do not run diff between different kind
                 * of objects.
@@ -1613,6 +1929,8 @@ static void builtin_diff(const char *name_a,
                if (complete_rewrite &&
                    (textconv_one || !diff_filespec_is_binary(one)) &&
                    (textconv_two || !diff_filespec_is_binary(two))) {
+                       fprintf(o->file, "%s", header.buf);
+                       strbuf_reset(&header);
                        emit_rewrite_diff(name_a, name_b, one, two,
                                                textconv_one, textconv_two, o);
                        o->found_changes = 1;
@@ -1620,21 +1938,25 @@ static void builtin_diff(const char *name_a,
                }
        }
 
-       if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
-               die("unable to read files to diff");
-
        if (!DIFF_OPT_TST(o, TEXT) &&
-           ( (diff_filespec_is_binary(one) && !textconv_one) ||
-             (diff_filespec_is_binary(two) && !textconv_two) )) {
+           ( (!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)
+                       die("unable to read files to diff");
                /* Quite common confusing case */
                if (mf1.size == mf2.size &&
-                   !memcmp(mf1.ptr, mf2.ptr, mf1.size))
+                   !memcmp(mf1.ptr, mf2.ptr, mf1.size)) {
+                       if (must_show_header)
+                               fprintf(o->file, "%s", header.buf);
                        goto free_ab_and_return;
+               }
+               fprintf(o->file, "%s", header.buf);
+               strbuf_reset(&header);
                if (DIFF_OPT_TST(o, BINARY))
-                       emit_binary_diff(o->file, &mf1, &mf2);
+                       emit_binary_diff(o->file, &mf1, &mf2, line_prefix);
                else
-                       fprintf(o->file, "Binary files %s and %s differ\n",
-                               lbl[0], lbl[1]);
+                       fprintf(o->file, "%sBinary files %s and %s differ\n",
+                               line_prefix, lbl[0], lbl[1]);
                o->found_changes = 1;
        }
        else {
@@ -1642,25 +1964,17 @@ static void builtin_diff(const char *name_a,
                const char *diffopts = getenv("GIT_DIFF_OPTS");
                xpparam_t xpp;
                xdemitconf_t xecfg;
-               xdemitcb_t ecb;
                struct emit_callback ecbdata;
                const struct userdiff_funcname *pe;
 
-               if (textconv_one) {
-                       size_t size;
-                       mf1.ptr = run_textconv(textconv_one, one, &size);
-                       if (!mf1.ptr)
-                               die("unable to read files to diff");
-                       mf1.size = size;
-               }
-               if (textconv_two) {
-                       size_t size;
-                       mf2.ptr = run_textconv(textconv_two, two, &size);
-                       if (!mf2.ptr)
-                               die("unable to read files to diff");
-                       mf2.size = size;
+               if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS) || must_show_header) {
+                       fprintf(o->file, "%s", header.buf);
+                       strbuf_reset(&header);
                }
 
+               mf1.size = fill_textconv(textconv_one, one, &mf1.ptr);
+               mf2.size = fill_textconv(textconv_two, two, &mf2.ptr);
+
                pe = diff_funcname_pattern(one);
                if (!pe)
                        pe = diff_funcname_pattern(two);
@@ -1674,8 +1988,9 @@ static void builtin_diff(const char *name_a,
                ecbdata.ws_rule = whitespace_rule(name_b ? name_b : name_a);
                if (ecbdata.ws_rule & WS_BLANK_AT_EOF)
                        check_blank_at_eof(&mf1, &mf2, &ecbdata);
-               ecbdata.file = o->file;
-               xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
+               ecbdata.opt = o;
+               ecbdata.header = header.len ? &header : NULL;
+               xpp.flags = o->xdl_opts;
                xecfg.ctxlen = o->context;
                xecfg.interhunkctxlen = o->interhunkcontext;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
@@ -1687,10 +2002,13 @@ static void builtin_diff(const char *name_a,
                        xecfg.ctxlen = strtoul(diffopts + 10, NULL, 10);
                else if (!prefixcmp(diffopts, "-u"))
                        xecfg.ctxlen = strtoul(diffopts + 2, NULL, 10);
-               if (DIFF_OPT_TST(o, COLOR_DIFF_WORDS)) {
+               if (o->word_diff) {
+                       int i;
+
                        ecbdata.diff_words =
                                xcalloc(1, sizeof(struct diff_words_data));
-                       ecbdata.diff_words->file = o->file;
+                       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)
@@ -1706,10 +2024,23 @@ static void builtin_diff(const char *name_a,
                                        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);
+                       }
                }
                xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
-                             &xpp, &xecfg, &ecb);
-               if (DIFF_OPT_TST(o, COLOR_DIFF_WORDS))
+                             &xpp, &xecfg);
+               if (o->word_diff)
                        free_diff_words_data(&ecbdata);
                if (textconv_one)
                        free(mf1.ptr);
@@ -1719,6 +2050,7 @@ static void builtin_diff(const char *name_a,
        }
 
  free_ab_and_return:
+       strbuf_release(&header);
        diff_free_filespec_data(one);
        diff_free_filespec_data(two);
        free(a_one);
@@ -1760,13 +2092,12 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;
-               xdemitcb_t ecb;
 
                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
-               xpp.flags = XDF_NEED_MINIMAL | o->xdl_opts;
+               xpp.flags = o->xdl_opts;
                xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
-                             &xpp, &xecfg, &ecb);
+                             &xpp, &xecfg);
        }
 
  free_and_return:
@@ -1791,6 +2122,7 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
        data.lineno = 0;
        data.o = o;
        data.ws_rule = whitespace_rule(attr_path);
+       data.conflict_marker_size = ll_merge_marker_size(attr_path);
 
        if (fill_mmfile(&mf1, one) < 0 || fill_mmfile(&mf2, two) < 0)
                die("unable to read files to diff");
@@ -1807,14 +2139,13 @@ static void builtin_checkdiff(const char *name_a, const char *name_b,
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;
-               xdemitcb_t ecb;
 
                memset(&xpp, 0, sizeof(xpp));
                memset(&xecfg, 0, sizeof(xecfg));
                xecfg.ctxlen = 1; /* at least one context line */
-               xpp.flags = XDF_NEED_MINIMAL;
+               xpp.flags = 0;
                xdi_diff_outf(&mf1, &mf2, checkdiff_consume, &data,
-                             &xpp, &xecfg, &ecb);
+                             &xpp, &xecfg);
 
                if (data.ws_rule & WS_BLANK_AT_EOF) {
                        struct emit_callback ecbdata;
@@ -1928,7 +2259,7 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int
         * If ce is marked as "assume unchanged", there is no
         * guarantee that work tree matches what we are looking for.
         */
-       if (ce->ce_flags & CE_VALID)
+       if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
                return 0;
 
        /*
@@ -1960,9 +2291,14 @@ static int populate_from_stdin(struct diff_filespec *s)
 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 {
        int len;
-       char *data = xmalloc(100);
+       char *data = xmalloc(100), *dirty = "";
+
+       /* Are we looking at the work tree? */
+       if (s->dirty_submodule)
+               dirty = "-dirty";
+
        len = snprintf(data, 100,
-               "Subproject commit %s\n", sha1_to_hex(s->sha1));
+                      "Subproject commit %s%s\n", sha1_to_hex(s->sha1), dirty);
        s->data = data;
        s->size = len;
        s->should_free = 1;
@@ -2225,7 +2561,7 @@ static void run_external_diff(const char *pgm,
        }
        *arg = NULL;
        fflush(NULL);
-       retval = run_command_v_opt(spawn_arg, 0);
+       retval = run_command_v_opt(spawn_arg, RUN_USING_SHELL);
        remove_tempfile();
        if (retval) {
                fprintf(stderr, "external diff died, stopping at %s.\n", name);
@@ -2244,36 +2580,53 @@ static void fill_metainfo(struct strbuf *msg,
                          struct diff_filespec *one,
                          struct diff_filespec *two,
                          struct diff_options *o,
-                         struct diff_filepair *p)
+                         struct diff_filepair *p,
+                         int *must_show_header,
+                         int use_color)
 {
+       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 = "";
+
+       *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:
-               strbuf_addf(msg, "similarity index %d%%", similarity_index(p));
-               strbuf_addstr(msg, "\ncopy from ");
+               strbuf_addf(msg, "%s%ssimilarity index %d%%",
+                           line_prefix, set, similarity_index(p));
+               strbuf_addf(msg, "%s\n%s%scopy from ",
+                           reset,  line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
-               strbuf_addstr(msg, "\ncopy to ");
+               strbuf_addf(msg, "%s\n%s%scopy to ", reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_RENAMED:
-               strbuf_addf(msg, "similarity index %d%%", similarity_index(p));
-               strbuf_addstr(msg, "\nrename from ");
+               strbuf_addf(msg, "%s%ssimilarity index %d%%",
+                           line_prefix, set, similarity_index(p));
+               strbuf_addf(msg, "%s\n%s%srename from ",
+                           reset, line_prefix, set);
                quote_c_style(name, msg, NULL, 0);
-               strbuf_addstr(msg, "\nrename to ");
+               strbuf_addf(msg, "%s\n%s%srename to ",
+                           reset, line_prefix, set);
                quote_c_style(other, msg, NULL, 0);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
                break;
        case DIFF_STATUS_MODIFIED:
                if (p->score) {
-                       strbuf_addf(msg, "dissimilarity index %d%%\n",
-                                   similarity_index(p));
+                       strbuf_addf(msg, "%s%sdissimilarity index %d%%%s\n",
+                                   line_prefix,
+                                   set, similarity_index(p), reset);
                        break;
                }
                /* fallthru */
        default:
-               /* nothing */
-               ;
+               *must_show_header = 0;
        }
        if (one && two && hashcmp(one->sha1, two->sha1)) {
                int abbrev = DIFF_OPT_TST(o, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
@@ -2284,15 +2637,13 @@ static void fill_metainfo(struct strbuf *msg,
                            (!fill_mmfile(&mf, two) && diff_filespec_is_binary(two)))
                                abbrev = 40;
                }
-               strbuf_addf(msg, "index %.*s..%.*s",
-                           abbrev, sha1_to_hex(one->sha1),
-                           abbrev, sha1_to_hex(two->sha1));
+               strbuf_addf(msg, "%s%sindex %s..", line_prefix, set,
+                           find_unique_abbrev(one->sha1, abbrev));
+               strbuf_addstr(msg, find_unique_abbrev(two->sha1, abbrev));
                if (one->mode == two->mode)
                        strbuf_addf(msg, " %06o", one->mode);
-               strbuf_addch(msg, '\n');
+               strbuf_addf(msg, "%s\n", reset);
        }
-       if (msg->len)
-               strbuf_setlen(msg, msg->len - 1);
 }
 
 static void run_diff_cmd(const char *pgm,
@@ -2307,11 +2658,7 @@ static void run_diff_cmd(const char *pgm,
 {
        const char *xfrm_msg = NULL;
        int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
-
-       if (msg) {
-               fill_metainfo(msg, name, other, one, two, o, p);
-               xfrm_msg = msg->len ? msg->buf : NULL;
-       }
+       int must_show_header = 0;
 
        if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
                pgm = NULL;
@@ -2321,6 +2668,17 @@ static void run_diff_cmd(const char *pgm,
                        pgm = drv->external;
        }
 
+       if (msg) {
+               /*
+                * don't use colors when the header is intended for an
+                * external diff driver
+                */
+               fill_metainfo(msg, name, other, one, two, o, p,
+                             &must_show_header,
+                             DIFF_OPT_TST(o, COLOR_DIFF) && !pgm);
+               xfrm_msg = msg->len ? msg->buf : NULL;
+       }
+
        if (pgm) {
                run_external_diff(pgm, name, other, one, two, xfrm_msg,
                                  complete_rewrite);
@@ -2328,7 +2686,8 @@ static void run_diff_cmd(const char *pgm,
        }
        if (one && two)
                builtin_diff(name, other ? other : name,
-                            one, two, xfrm_msg, o, complete_rewrite);
+                            one, two, xfrm_msg, must_show_header,
+                            o, complete_rewrite);
        else
                fprintf(o->file, "* Unmerged path %s\n", name);
 }
@@ -2355,10 +2714,16 @@ static void diff_fill_sha1_info(struct diff_filespec *one)
 static void strip_prefix(int prefix_length, const char **namep, const char **otherp)
 {
        /* Strip the prefix but do not molest /dev/null and absolute paths */
-       if (*namep && **namep != '/')
+       if (*namep && **namep != '/') {
                *namep += prefix_length;
-       if (*otherp && **otherp != '/')
+               if (**namep == '/')
+                       ++*namep;
+       }
+       if (*otherp && **otherp != '/') {
                *otherp += prefix_length;
+               if (**otherp == '/')
+                       ++*otherp;
+       }
 }
 
 static void run_diff(struct diff_filepair *p, struct diff_options *o)
@@ -2464,7 +2829,7 @@ static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
 
 void diff_setup(struct diff_options *options)
 {
-       memset(options, 0, sizeof(*options));
+       memcpy(options, &default_diff_options, sizeof(*options));
 
        options->file = stdout;
 
@@ -2480,7 +2845,9 @@ void diff_setup(struct diff_options *options)
                DIFF_OPT_SET(options, COLOR_DIFF);
        options->detect_rename = diff_detect_rename_default;
 
-       if (!diff_mnemonic_prefix) {
+       if (diff_no_prefix) {
+               options->a_prefix = options->b_prefix = "";
+       } else if (!diff_mnemonic_prefix) {
                options->a_prefix = "a/";
                options->b_prefix = "b/";
        }
@@ -2501,6 +2868,20 @@ int diff_setup_done(struct diff_options *options)
        if (count > 1)
                die("--name-only, --name-status, --check and -s are mutually exclusive");
 
+       /*
+        * Most of the time we can say "there are changes"
+        * only by checking if there are changed paths, but
+        * --ignore-whitespace* options force us to look
+        * inside contents.
+        */
+
+       if (DIFF_XDL_TST(options, IGNORE_WHITESPACE) ||
+           DIFF_XDL_TST(options, IGNORE_WHITESPACE_CHANGE) ||
+           DIFF_XDL_TST(options, IGNORE_WHITESPACE_AT_EOL))
+               DIFF_OPT_SET(options, DIFF_FROM_CONTENTS);
+       else
+               DIFF_OPT_CLR(options, DIFF_FROM_CONTENTS);
+
        if (DIFF_OPT_TST(options, FIND_COPIES_HARDER))
                options->detect_rename = DIFF_DETECT_COPY;
 
@@ -2540,6 +2921,12 @@ int diff_setup_done(struct diff_options *options)
         */
        if (options->pickaxe)
                DIFF_OPT_SET(options, RECURSIVE);
+       /*
+        * When patches are generated, submodules diffed against the work tree
+        * must be checked for dirtiness too so it can be shown in the output
+        */
+       if (options->output_format & DIFF_FORMAT_PATCH)
+               DIFF_OPT_SET(options, DIRTY_SUBMODULES);
 
        if (options->detect_rename && options->rename_limit < 0)
                options->rename_limit = diff_rename_limit_default;
@@ -2561,7 +2948,7 @@ int diff_setup_done(struct diff_options *options)
         * to have found.  It does not make sense not to return with
         * exit code in such a case either.
         */
-       if (DIFF_OPT_TST(options, QUIET)) {
+       if (DIFF_OPT_TST(options, QUICK)) {
                options->output_format = DIFF_FORMAT_NO_OUTPUT;
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        }
@@ -2618,12 +3005,103 @@ static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *va
 
 static int diff_scoreopt_parse(const char *opt);
 
+static inline int short_opt(char opt, const char **argv,
+                           const char **optarg)
+{
+       const char *arg = argv[0];
+       if (arg[0] != '-' || arg[1] != opt)
+               return 0;
+       if (arg[2] != '\0') {
+               *optarg = arg + 2;
+               return 1;
+       }
+       if (!argv[1])
+               die("Option '%c' requires a value", opt);
+       *optarg = argv[1];
+       return 2;
+}
+
+int parse_long_opt(const char *opt, const char **argv,
+                  const char **optarg)
+{
+       const char *arg = argv[0];
+       if (arg[0] != '-' || arg[1] != '-')
+               return 0;
+       arg += strlen("--");
+       if (prefixcmp(arg, opt))
+               return 0;
+       arg += strlen(opt);
+       if (*arg == '=') { /* sticked form: --option=value */
+               *optarg = arg + 1;
+               return 1;
+       }
+       if (*arg != '\0')
+               return 0;
+       /* separate form: --option value */
+       if (!argv[1])
+               die("Option '--%s' requires a value", opt);
+       *optarg = argv[1];
+       return 2;
+}
+
+static int stat_opt(struct diff_options *options, const char **av)
+{
+       const char *arg = av[0];
+       char *end;
+       int width = options->stat_width;
+       int name_width = options->stat_name_width;
+       int argcount = 1;
+
+       arg += strlen("--stat");
+       end = (char *)arg;
+
+       switch (*arg) {
+       case '-':
+               if (!prefixcmp(arg, "-width")) {
+                       arg += strlen("-width");
+                       if (*arg == '=')
+                               width = strtoul(arg + 1, &end, 10);
+                       else if (!*arg && !av[1])
+                               die("Option '--stat-width' requires a value");
+                       else if (!*arg) {
+                               width = strtoul(av[1], &end, 10);
+                               argcount = 2;
+                       }
+               } else if (!prefixcmp(arg, "-name-width")) {
+                       arg += strlen("-name-width");
+                       if (*arg == '=')
+                               name_width = strtoul(arg + 1, &end, 10);
+                       else if (!*arg && !av[1])
+                               die("Option '--stat-name-width' requires a value");
+                       else if (!*arg) {
+                               name_width = strtoul(av[1], &end, 10);
+                               argcount = 2;
+                       }
+               }
+               break;
+       case '=':
+               width = strtoul(arg+1, &end, 10);
+               if (*end == ',')
+                       name_width = strtoul(end+1, &end, 10);
+       }
+
+       /* Important! This checks all the error cases! */
+       if (*end)
+               return 0;
+       options->output_format |= DIFF_FORMAT_DIFFSTAT;
+       options->stat_name_width = name_width;
+       options->stat_width = width;
+       return argcount;
+}
+
 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 {
        const char *arg = av[0];
+       const char *optarg;
+       int argcount;
 
        /* Output format options */
-       if (!strcmp(arg, "-p") || !strcmp(arg, "-u"))
+       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;
@@ -2657,33 +3135,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                options->output_format |= DIFF_FORMAT_NAME_STATUS;
        else if (!strcmp(arg, "-s"))
                options->output_format |= DIFF_FORMAT_NO_OUTPUT;
-       else if (!prefixcmp(arg, "--stat")) {
-               char *end;
-               int width = options->stat_width;
-               int name_width = options->stat_name_width;
-               arg += 6;
-               end = (char *)arg;
-
-               switch (*arg) {
-               case '-':
-                       if (!prefixcmp(arg, "-width="))
-                               width = strtoul(arg + 7, &end, 10);
-                       else if (!prefixcmp(arg, "-name-width="))
-                               name_width = strtoul(arg + 12, &end, 10);
-                       break;
-               case '=':
-                       width = strtoul(arg+1, &end, 10);
-                       if (*end == ',')
-                               name_width = strtoul(end+1, &end, 10);
-               }
-
-               /* Important! This checks all the error cases! */
-               if (*end)
-                       return 0;
-               options->output_format |= DIFF_FORMAT_DIFFSTAT;
-               options->stat_name_width = name_width;
-               options->stat_width = width;
-       }
+       else if (!prefixcmp(arg, "--stat"))
+               /* --stat, --stat-width, or --stat-name-width */
+               return stat_opt(options, av);
 
        /* renames options */
        else if (!prefixcmp(arg, "-B")) {
@@ -2738,21 +3192,55 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                DIFF_OPT_SET(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
+                       return error("option `color' expects \"always\", \"auto\", or \"never\"");
+       }
        else if (!strcmp(arg, "--no-color"))
                DIFF_OPT_CLR(options, COLOR_DIFF);
        else if (!strcmp(arg, "--color-words")) {
                DIFF_OPT_SET(options, COLOR_DIFF);
-               DIFF_OPT_SET(options, COLOR_DIFF_WORDS);
+               options->word_diff = DIFF_WORDS_COLOR;
        }
        else if (!prefixcmp(arg, "--color-words=")) {
                DIFF_OPT_SET(options, COLOR_DIFF);
-               DIFF_OPT_SET(options, COLOR_DIFF_WORDS);
+               options->word_diff = DIFF_WORDS_COLOR;
                options->word_regex = arg + 14;
        }
+       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"))
+                       options->word_diff = DIFF_WORDS_PLAIN;
+               else if (!strcmp(type, "color")) {
+                       DIFF_OPT_SET(options, COLOR_DIFF);
+                       options->word_diff = DIFF_WORDS_COLOR;
+               }
+               else if (!strcmp(type, "porcelain"))
+                       options->word_diff = DIFF_WORDS_PORCELAIN;
+               else if (!strcmp(type, "none"))
+                       options->word_diff = DIFF_WORDS_NONE;
+               else
+                       die("bad --word-diff argument: %s", type);
+       }
+       else if ((argcount = parse_long_opt("word-diff-regex", av, &optarg))) {
+               if (options->word_diff == DIFF_WORDS_NONE)
+                       options->word_diff = DIFF_WORDS_PLAIN;
+               options->word_regex = optarg;
+               return argcount;
+       }
        else if (!strcmp(arg, "--exit-code"))
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        else if (!strcmp(arg, "--quiet"))
-               DIFF_OPT_SET(options, QUIET);
+               DIFF_OPT_SET(options, QUICK);
        else if (!strcmp(arg, "--ext-diff"))
                DIFF_OPT_SET(options, ALLOW_EXTERNAL);
        else if (!strcmp(arg, "--no-ext-diff"))
@@ -2761,24 +3249,42 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                DIFF_OPT_SET(options, ALLOW_TEXTCONV);
        else if (!strcmp(arg, "--no-textconv"))
                DIFF_OPT_CLR(options, ALLOW_TEXTCONV);
-       else if (!strcmp(arg, "--ignore-submodules"))
-               DIFF_OPT_SET(options, IGNORE_SUBMODULES);
+       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=")) {
+               DIFF_OPT_SET(options, OVERRIDE_SUBMODULE_CONFIG);
+               handle_ignore_submodules_arg(options, arg + 20);
+       } 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);
+       }
 
        /* misc options */
        else if (!strcmp(arg, "-z"))
                options->line_termination = 0;
-       else if (!prefixcmp(arg, "-l"))
-               options->rename_limit = strtoul(arg+2, NULL, 10);
-       else if (!prefixcmp(arg, "-S"))
-               options->pickaxe = arg + 2;
+       else if ((argcount = short_opt('l', av, &optarg))) {
+               options->rename_limit = strtoul(optarg, NULL, 10);
+               return argcount;
+       }
+       else if ((argcount = short_opt('S', av, &optarg))) {
+               options->pickaxe = optarg;
+               return argcount;
+       }
        else if (!strcmp(arg, "--pickaxe-all"))
                options->pickaxe_opts = DIFF_PICKAXE_ALL;
        else if (!strcmp(arg, "--pickaxe-regex"))
                options->pickaxe_opts = DIFF_PICKAXE_REGEX;
-       else if (!prefixcmp(arg, "-O"))
-               options->orderfile = arg + 2;
-       else if (!prefixcmp(arg, "--diff-filter="))
-               options->filter = arg + 14;
+       else if ((argcount = short_opt('O', av, &optarg))) {
+               options->orderfile = optarg;
+               return argcount;
+       }
+       else if ((argcount = parse_long_opt("diff-filter", av, &optarg))) {
+               options->filter = optarg;
+               return argcount;
+       }
        else if (!strcmp(arg, "--abbrev"))
                options->abbrev = DEFAULT_ABBREV;
        else if (!prefixcmp(arg, "--abbrev=")) {
@@ -2788,20 +3294,25 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                else if (40 < options->abbrev)
                        options->abbrev = 40;
        }
-       else if (!prefixcmp(arg, "--src-prefix="))
-               options->a_prefix = arg + 13;
-       else if (!prefixcmp(arg, "--dst-prefix="))
-               options->b_prefix = arg + 13;
+       else if ((argcount = parse_long_opt("src-prefix", av, &optarg))) {
+               options->a_prefix = optarg;
+               return argcount;
+       }
+       else if ((argcount = parse_long_opt("dst-prefix", av, &optarg))) {
+               options->b_prefix = optarg;
+               return argcount;
+       }
        else if (!strcmp(arg, "--no-prefix"))
                options->a_prefix = options->b_prefix = "";
        else if (opt_arg(arg, '\0', "inter-hunk-context",
                         &options->interhunkcontext))
                ;
-       else if (!prefixcmp(arg, "--output=")) {
-               options->file = fopen(arg + strlen("--output="), "w");
+       else if ((argcount = parse_long_opt("output", av, &optarg))) {
+               options->file = fopen(optarg, "w");
                if (!options->file)
                        die_errno("Could not open '%s'", arg + strlen("--output="));
                options->close_file = 1;
+               return argcount;
        } else
                return 0;
        return 1;
@@ -2929,6 +3440,11 @@ 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);
+       }
 
        if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
                fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
@@ -2983,7 +3499,8 @@ int diff_unmodified_pair(struct diff_filepair *p)
         * dealing with a change.
         */
        if (one->sha1_valid && two->sha1_valid &&
-           !hashcmp(one->sha1, two->sha1))
+           !hashcmp(one->sha1, two->sha1) &&
+           !one->dirty_submodule && !two->dirty_submodule)
                return 1; /* no change */
        if (!one->sha1_valid && !two->sha1_valid)
                return 1; /* both look at the same file on the filesystem. */
@@ -3118,6 +3635,8 @@ static void diff_resolve_rename_copy(void)
                }
                else if (hashcmp(p->one->sha1, p->two->sha1) ||
                         p->one->mode != p->two->mode ||
+                        p->one->dirty_submodule ||
+                        p->two->dirty_submodule ||
                         is_null_sha1(p->one->sha1))
                        p->status = DIFF_STATUS_MODIFIED;
                else {
@@ -3171,48 +3690,62 @@ static void show_file_mode_name(FILE *file, const char *newdelete, struct diff_f
 }
 
 
-static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name)
+static void show_mode_change(FILE *file, struct diff_filepair *p, int show_name,
+               const char *line_prefix)
 {
        if (p->one->mode && p->two->mode && p->one->mode != p->two->mode) {
-               fprintf(file, " mode change %06o => %06o%c", p->one->mode, p->two->mode,
-                       show_name ? ' ' : '\n');
+               fprintf(file, "%s mode change %06o => %06o%c", line_prefix, p->one->mode,
+                       p->two->mode, show_name ? ' ' : '\n');
                if (show_name) {
                        write_name_quoted(p->two->path, file, '\n');
                }
        }
 }
 
-static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p)
+static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_filepair *p,
+                       const char *line_prefix)
 {
        char *names = pprint_rename(p->one->path, p->two->path);
 
        fprintf(file, " %s %s (%d%%)\n", renamecopy, names, similarity_index(p));
        free(names);
-       show_mode_change(file, p, 0);
+       show_mode_change(file, p, 0, line_prefix);
 }
 
-static void diff_summary(FILE *file, struct diff_filepair *p)
+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;
+       }
+
        switch(p->status) {
        case DIFF_STATUS_DELETED:
+               fputs(line_prefix, file);
                show_file_mode_name(file, "delete", p->one);
                break;
        case DIFF_STATUS_ADDED:
+               fputs(line_prefix, file);
                show_file_mode_name(file, "create", p->two);
                break;
        case DIFF_STATUS_COPIED:
-               show_rename_copy(file, "copy", p);
+               fputs(line_prefix, file);
+               show_rename_copy(file, "copy", p, line_prefix);
                break;
        case DIFF_STATUS_RENAMED:
-               show_rename_copy(file, "rename", p);
+               fputs(line_prefix, file);
+               show_rename_copy(file, "rename", p, line_prefix);
                break;
        default:
                if (p->score) {
-                       fputs(" rewrite ", file);
+                       fprintf(file, "%s rewrite ", line_prefix);
                        write_name_quoted(p->two->path, file, ' ');
                        fprintf(file, "(%d%%)\n", similarity_index(p));
                }
-               show_mode_change(file, p, !p->score);
+               show_mode_change(file, p, !p->score, line_prefix);
                break;
        }
 }
@@ -3266,7 +3799,6 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
        for (i = 0; i < q->nr; i++) {
                xpparam_t xpp;
                xdemitconf_t xecfg;
-               xdemitcb_t ecb;
                mmfile_t mf1, mf2;
                struct diff_filepair *p = q->queue[i];
                int len1, len2;
@@ -3324,11 +3856,18 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
                                        len2, p->two->path);
                git_SHA1_Update(&ctx, buffer, len1);
 
-               xpp.flags = XDF_NEED_MINIMAL;
+               if (diff_filespec_is_binary(p->one) ||
+                   diff_filespec_is_binary(p->two)) {
+                       git_SHA1_Update(&ctx, sha1_to_hex(p->one->sha1), 40);
+                       git_SHA1_Update(&ctx, sha1_to_hex(p->two->sha1), 40);
+                       continue;
+               }
+
+               xpp.flags = 0;
                xecfg.ctxlen = 3;
                xecfg.flags = XDL_EMIT_FUNCNAMES;
                xdi_diff_outf(&mf1, &mf2, patch_id_consume, &data,
-                             &xpp, &xecfg, &ecb);
+                             &xpp, &xecfg);
        }
 
        git_SHA1_Final(sha1, &ctx);
@@ -3345,8 +3884,7 @@ int diff_flush_patch_id(struct diff_options *options, unsigned char *sha1)
                diff_free_filepair(q->queue[i]);
 
        free(q->queue);
-       q->queue = NULL;
-       q->nr = q->alloc = 0;
+       DIFF_QUEUE_CLEAR(q);
 
        return result;
 }
@@ -3423,11 +3961,35 @@ void diff_flush(struct diff_options *options)
                show_dirstat(options);
 
        if (output_format & DIFF_FORMAT_SUMMARY && !is_summary_empty(q)) {
-               for (i = 0; i < q->nr; i++)
-                       diff_summary(options->file, q->queue[i]);
+               for (i = 0; i < q->nr; i++) {
+                       diff_summary(options, q->queue[i]);
+               }
                separator++;
        }
 
+       if (output_format & DIFF_FORMAT_NO_OUTPUT &&
+           DIFF_OPT_TST(options, EXIT_WITH_STATUS) &&
+           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
+                * aren't supposed to produce any output anyway.
+                */
+               if (options->close_file)
+                       fclose(options->file);
+               options->file = fopen("/dev/null", "w");
+               if (!options->file)
+                       die_errno("Could not open /dev/null");
+               options->close_file = 1;
+               for (i = 0; i < q->nr; i++) {
+                       struct diff_filepair *p = q->queue[i];
+                       if (check_pair_status(p))
+                               diff_flush_patch(p, options);
+                       if (options->found_changes)
+                               break;
+               }
+       }
+
        if (output_format & DIFF_FORMAT_PATCH) {
                if (separator) {
                        putc(options->line_termination, options->file);
@@ -3451,10 +4013,21 @@ void diff_flush(struct diff_options *options)
                diff_free_filepair(q->queue[i]);
 free_queue:
        free(q->queue);
-       q->queue = NULL;
-       q->nr = q->alloc = 0;
+       DIFF_QUEUE_CLEAR(q);
        if (options->close_file)
                fclose(options->file);
+
+       /*
+        * Report the content-level differences with HAS_CHANGES;
+        * diff_addremove/diff_change does not set the bit when
+        * DIFF_FROM_CONTENTS is in effect (e.g. with -w).
+        */
+       if (DIFF_OPT_TST(options, DIFF_FROM_CONTENTS)) {
+               if (options->found_changes)
+                       DIFF_OPT_SET(options, HAS_CHANGES);
+               else
+                       DIFF_OPT_CLR(options, HAS_CHANGES);
+       }
 }
 
 static void diffcore_apply_filter(const char *filter)
@@ -3462,8 +4035,7 @@ static void diffcore_apply_filter(const char *filter)
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
-       outq.queue = NULL;
-       outq.nr = outq.alloc = 0;
+       DIFF_QUEUE_CLEAR(&outq);
 
        if (!filter)
                return;
@@ -3531,14 +4103,13 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
        int i;
        struct diff_queue_struct *q = &diff_queued_diff;
        struct diff_queue_struct outq;
-       outq.queue = NULL;
-       outq.nr = outq.alloc = 0;
+       DIFF_QUEUE_CLEAR(&outq);
 
        for (i = 0; i < q->nr; i++) {
                struct diff_filepair *p = q->queue[i];
 
                /*
-                * 1. Entries that come from stat info dirtyness
+                * 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
@@ -3574,27 +4145,51 @@ static void diffcore_skip_stat_unmatch(struct diff_options *diffopt)
        *q = outq;
 }
 
+static int diffnamecmp(const void *a_, const void *b_)
+{
+       const struct diff_filepair *a = *((const struct diff_filepair **)a_);
+       const struct diff_filepair *b = *((const struct diff_filepair **)b_);
+       const char *name_a, *name_b;
+
+       name_a = a->one ? a->one->path : a->two->path;
+       name_b = b->one ? b->one->path : b->two->path;
+       return strcmp(name_a, name_b);
+}
+
+void diffcore_fix_diff_index(struct diff_options *options)
+{
+       struct diff_queue_struct *q = &diff_queued_diff;
+       qsort(q->queue, q->nr, sizeof(q->queue[0]), diffnamecmp);
+}
+
 void diffcore_std(struct diff_options *options)
 {
        if (options->skip_stat_unmatch)
                diffcore_skip_stat_unmatch(options);
-       if (options->break_opt != -1)
-               diffcore_break(options->break_opt);
-       if (options->detect_rename)
-               diffcore_rename(options);
-       if (options->break_opt != -1)
-               diffcore_merge_broken();
+       if (!options->found_follow) {
+               /* See try_to_follow_renames() in tree-diff.c */
+               if (options->break_opt != -1)
+                       diffcore_break(options->break_opt);
+               if (options->detect_rename)
+                       diffcore_rename(options);
+               if (options->break_opt != -1)
+                       diffcore_merge_broken();
+       }
        if (options->pickaxe)
                diffcore_pickaxe(options->pickaxe, options->pickaxe_opts);
        if (options->orderfile)
                diffcore_order(options->orderfile);
-       diff_resolve_rename_copy();
+       if (!options->found_follow)
+               /* See try_to_follow_renames() in tree-diff.c */
+               diff_resolve_rename_copy();
        diffcore_apply_filter(options->filter);
 
-       if (diff_queued_diff.nr)
+       if (diff_queued_diff.nr && !DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
                DIFF_OPT_SET(options, HAS_CHANGES);
        else
                DIFF_OPT_CLR(options, HAS_CHANGES);
+
+       options->found_follow = 0;
 }
 
 int diff_result_code(struct diff_options *opt, int status)
@@ -3612,14 +4207,32 @@ int diff_result_code(struct diff_options *opt, int status)
        return result;
 }
 
+/*
+ * Shall changes to this submodule be ignored?
+ *
+ * Submodule changes can be configured to be ignored separately for each path,
+ * but that configuration can be overridden from the command line.
+ */
+static int is_submodule_ignored(const char *path, struct diff_options *options)
+{
+       int ignored = 0;
+       unsigned orig_flags = options->flags;
+       if (!DIFF_OPT_TST(options, OVERRIDE_SUBMODULE_CONFIG))
+               set_diffopt_flags_from_submodule_config(options, path);
+       if (DIFF_OPT_TST(options, IGNORE_SUBMODULES))
+               ignored = 1;
+       options->flags = orig_flags;
+       return ignored;
+}
+
 void diff_addremove(struct diff_options *options,
                    int addremove, unsigned mode,
                    const unsigned char *sha1,
-                   const char *concatpath)
+                   const char *concatpath, unsigned dirty_submodule)
 {
        struct diff_filespec *one, *two;
 
-       if (DIFF_OPT_TST(options, IGNORE_SUBMODULES) && S_ISGITLINK(mode))
+       if (S_ISGITLINK(mode) && is_submodule_ignored(concatpath, options))
                return;
 
        /* This may look odd, but it is a preparation for
@@ -3647,23 +4260,27 @@ void diff_addremove(struct diff_options *options,
 
        if (addremove != '+')
                fill_filespec(one, sha1, mode);
-       if (addremove != '-')
+       if (addremove != '-') {
                fill_filespec(two, sha1, mode);
+               two->dirty_submodule = dirty_submodule;
+       }
 
        diff_queue(&diff_queued_diff, one, two);
-       DIFF_OPT_SET(options, HAS_CHANGES);
+       if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
+               DIFF_OPT_SET(options, HAS_CHANGES);
 }
 
 void diff_change(struct diff_options *options,
                 unsigned old_mode, unsigned new_mode,
                 const unsigned char *old_sha1,
                 const unsigned char *new_sha1,
-                const char *concatpath)
+                const char *concatpath,
+                unsigned old_dirty_submodule, unsigned new_dirty_submodule)
 {
        struct diff_filespec *one, *two;
 
-       if (DIFF_OPT_TST(options, IGNORE_SUBMODULES) && S_ISGITLINK(old_mode)
-                       && S_ISGITLINK(new_mode))
+       if (S_ISGITLINK(old_mode) && S_ISGITLINK(new_mode) &&
+           is_submodule_ignored(concatpath, options))
                return;
 
        if (DIFF_OPT_TST(options, REVERSE_DIFF)) {
@@ -3671,6 +4288,8 @@ 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_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
+                       new_dirty_submodule = tmp;
        }
 
        if (options->prefix &&
@@ -3681,9 +4300,12 @@ void diff_change(struct diff_options *options,
        two = alloc_filespec(concatpath);
        fill_filespec(one, old_sha1, old_mode);
        fill_filespec(two, new_sha1, new_mode);
+       one->dirty_submodule = old_dirty_submodule;
+       two->dirty_submodule = new_dirty_submodule;
 
        diff_queue(&diff_queued_diff, one, two);
-       DIFF_OPT_SET(options, HAS_CHANGES);
+       if (!DIFF_OPT_TST(options, DIFF_FROM_CONTENTS))
+               DIFF_OPT_SET(options, HAS_CHANGES);
 }
 
 void diff_unmerge(struct diff_options *options,
@@ -3710,6 +4332,7 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
        const char **arg = argv;
        struct child_process child;
        struct strbuf buf = STRBUF_INIT;
+       int err = 0;
 
        temp = prepare_temp_file(spec->path, spec);
        *arg++ = pgm;
@@ -3717,19 +4340,68 @@ static char *run_textconv(const char *pgm, struct diff_filespec *spec,
        *arg = NULL;
 
        memset(&child, 0, sizeof(child));
+       child.use_shell = 1;
        child.argv = argv;
        child.out = -1;
-       if (start_command(&child) != 0 ||
-           strbuf_read(&buf, child.out, 0) < 0 ||
-           finish_command(&child) != 0) {
-               close(child.out);
-               strbuf_release(&buf);
+       if (start_command(&child)) {
                remove_tempfile();
-               error("error running textconv command '%s'", pgm);
                return NULL;
        }
+
+       if (strbuf_read(&buf, child.out, 0) < 0)
+               err = error("error reading from textconv command '%s'", pgm);
        close(child.out);
+
+       if (finish_command(&child) || err) {
+               strbuf_release(&buf);
+               remove_tempfile();
+               return NULL;
+       }
        remove_tempfile();
 
        return strbuf_detach(&buf, outsize);
 }
+
+size_t fill_textconv(struct userdiff_driver *driver,
+                    struct diff_filespec *df,
+                    char **outbuf)
+{
+       size_t size;
+
+       if (!driver || !driver->textconv) {
+               if (!DIFF_FILE_VALID(df)) {
+                       *outbuf = "";
+                       return 0;
+               }
+               if (diff_populate_filespec(df, 0))
+                       die("unable to read files to diff");
+               *outbuf = df->data;
+               return df->size;
+       }
+
+       if (driver->textconv_cache) {
+               *outbuf = notes_cache_get(driver->textconv_cache, df->sha1,
+                                         &size);
+               if (*outbuf)
+                       return size;
+       }
+
+       *outbuf = run_textconv(driver->textconv, df, &size);
+       if (!*outbuf)
+               die("unable to read files to diff");
+
+       if (driver->textconv_cache) {
+               /* ignore errors, as we might be in a readonly repository */
+               notes_cache_put(driver->textconv_cache, df->sha1, *outbuf,
+                               size);
+               /*
+                * we could save up changes and flush them all at the end,
+                * but we would need an extra call after all diffing is done.
+                * Since generating a cache entry is the slow path anyway,
+                * this extra overhead probably isn't a big deal.
+                */
+               notes_cache_write(driver->textconv_cache);
+       }
+
+       return size;
+}