push: require force for refs under refs/tags/
[gitweb.git] / diff.c
diff --git a/diff.c b/diff.c
index 8f2abc8fe4b73590cbdecbaaa5cfe75eb1a4829c..e89a2015eb794616416cd02a8f87695efc28d4bd 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -15,6 +15,7 @@
 #include "sigchain.h"
 #include "submodule.h"
 #include "ll-merge.h"
+#include "string-list.h"
 
 #ifdef NO_FAST_WORKING_DIRECTORY
 #define FAST_WORKING_DIRECTORY 0
 static int diff_detect_rename_default;
 static int diff_rename_limit_default = 400;
 static int diff_suppress_blank_empty;
-int diff_use_color_default = -1;
+static int diff_use_color_default = -1;
+static int diff_context_default = 3;
 static const char *diff_word_regex_cfg;
 static const char *external_diff_cmd_cfg;
 int diff_auto_refresh_index = 1;
 static int diff_mnemonic_prefix;
 static int diff_no_prefix;
+static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
 
@@ -67,26 +70,30 @@ static int parse_diff_color_slot(const char *var, int ofs)
        return -1;
 }
 
-static int parse_dirstat_params(struct diff_options *options, const char *params,
+static int parse_dirstat_params(struct diff_options *options, const char *params_string,
                                struct strbuf *errmsg)
 {
-       const char *p = params;
-       int p_len, ret = 0;
+       char *params_copy = xstrdup(params_string);
+       struct string_list params = STRING_LIST_INIT_NODUP;
+       int ret = 0;
+       int i;
 
-       while (*p) {
-               p_len = strchrnul(p, ',') - p;
-               if (!memcmp(p, "changes", p_len)) {
+       if (*params_copy)
+               string_list_split_in_place(&params, params_copy, ',', -1);
+       for (i = 0; i < params.nr; i++) {
+               const char *p = params.items[i].string;
+               if (!strcmp(p, "changes")) {
                        DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
                        DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
-               } else if (!memcmp(p, "lines", p_len)) {
+               } else if (!strcmp(p, "lines")) {
                        DIFF_OPT_SET(options, DIRSTAT_BY_LINE);
                        DIFF_OPT_CLR(options, DIRSTAT_BY_FILE);
-               } else if (!memcmp(p, "files", p_len)) {
+               } else if (!strcmp(p, "files")) {
                        DIFF_OPT_CLR(options, DIRSTAT_BY_LINE);
                        DIFF_OPT_SET(options, DIRSTAT_BY_FILE);
-               } else if (!memcmp(p, "noncumulative", p_len)) {
+               } else if (!strcmp(p, "noncumulative")) {
                        DIFF_OPT_CLR(options, DIRSTAT_CUMULATIVE);
-               } else if (!memcmp(p, "cumulative", p_len)) {
+               } else if (!strcmp(p, "cumulative")) {
                        DIFF_OPT_SET(options, DIRSTAT_CUMULATIVE);
                } else if (isdigit(*p)) {
                        char *end;
@@ -98,24 +105,21 @@ static int parse_dirstat_params(struct diff_options *options, const char *params
                                while (isdigit(*++end))
                                        ; /* nothing */
                        }
-                       if (end - p == p_len)
+                       if (!*end)
                                options->dirstat_permille = permille;
                        else {
-                               strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%.*s'\n"),
-                                           p_len, p);
+                               strbuf_addf(errmsg, _("  Failed to parse dirstat cut-off percentage '%s'\n"),
+                                           p);
                                ret++;
                        }
                } else {
-                       strbuf_addf(errmsg, _("  Unknown dirstat parameter '%.*s'\n"),
-                                   p_len, p);
+                       strbuf_addf(errmsg, _("  Unknown dirstat parameter '%s'\n"), p);
                        ret++;
                }
 
-               p += p_len;
-
-               if (*p)
-                       p++; /* more parameters, swallow separator */
        }
+       string_list_clear(&params, 0);
+       free(params_copy);
        return ret;
 }
 
@@ -140,6 +144,12 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
                diff_use_color_default = git_config_colorbool(var, value);
                return 0;
        }
+       if (!strcmp(var, "diff.context")) {
+               diff_context_default = git_config_int(var, value);
+               if (diff_context_default < 0)
+                       return -1;
+               return 0;
+       }
        if (!strcmp(var, "diff.renames")) {
                diff_detect_rename_default = git_config_rename(var, value);
                return 0;
@@ -156,6 +166,10 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
                diff_no_prefix = git_config_bool(var, value);
                return 0;
        }
+       if (!strcmp(var, "diff.statgraphwidth")) {
+               diff_stat_graph_width = git_config_int(var, value);
+               return 0;
+       }
        if (!strcmp(var, "diff.external"))
                return git_config_string(&external_diff_cmd_cfg, var, value);
        if (!strcmp(var, "diff.wordregex"))
@@ -177,11 +191,8 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
                return 0;
        }
 
-       switch (userdiff_config(var, value)) {
-               case 0: break;
-               case -1: return -1;
-               default: return 0;
-       }
+       if (userdiff_config(var, value) < 0)
+               return -1;
 
        if (!prefixcmp(var, "diff.color.") || !prefixcmp(var, "color.diff.")) {
                int slot = parse_diff_color_slot(var, 11);
@@ -572,6 +583,7 @@ static void emit_rewrite_lines(struct emit_callback *ecb,
        if (!endp) {
                const char *plain = diff_get_color(ecb->color_diff,
                                                   DIFF_PLAIN);
+               putc('\n', ecb->opt->file);
                emit_line_0(ecb->opt, plain, reset, '\\',
                            nneof, strlen(nneof));
        }
@@ -987,10 +999,74 @@ static void diff_words_flush(struct emit_callback *ecbdata)
                diff_words_show(ecbdata->diff_words);
 }
 
+static void diff_filespec_load_driver(struct diff_filespec *one)
+{
+       /* Use already-loaded driver */
+       if (one->driver)
+               return;
+
+       if (S_ISREG(one->mode))
+               one->driver = userdiff_find_by_path(one->path);
+
+       /* Fallback to default settings */
+       if (!one->driver)
+               one->driver = userdiff_find_by_name("default");
+}
+
+static const char *userdiff_word_regex(struct diff_filespec *one)
+{
+       diff_filespec_load_driver(one);
+       return one->driver->word_regex;
+}
+
+static void init_diff_words_data(struct emit_callback *ecbdata,
+                                struct diff_options *orig_opts,
+                                struct diff_filespec *one,
+                                struct diff_filespec *two)
+{
+       int i;
+       struct diff_options *o = xmalloc(sizeof(struct diff_options));
+       memcpy(o, orig_opts, sizeof(struct diff_options));
+
+       ecbdata->diff_words =
+               xcalloc(1, sizeof(struct diff_words_data));
+       ecbdata->diff_words->type = o->word_diff;
+       ecbdata->diff_words->opt = o;
+       if (!o->word_regex)
+               o->word_regex = userdiff_word_regex(one);
+       if (!o->word_regex)
+               o->word_regex = userdiff_word_regex(two);
+       if (!o->word_regex)
+               o->word_regex = diff_word_regex_cfg;
+       if (o->word_regex) {
+               ecbdata->diff_words->word_regex = (regex_t *)
+                       xmalloc(sizeof(regex_t));
+               if (regcomp(ecbdata->diff_words->word_regex,
+                           o->word_regex,
+                           REG_EXTENDED | REG_NEWLINE))
+                       die ("Invalid regular expression: %s",
+                            o->word_regex);
+       }
+       for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
+               if (o->word_diff == diff_words_styles[i].type) {
+                       ecbdata->diff_words->style =
+                               &diff_words_styles[i];
+                       break;
+               }
+       }
+       if (want_color(o->use_color)) {
+               struct diff_words_style *st = ecbdata->diff_words->style;
+               st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
+               st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
+               st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
+       }
+}
+
 static void free_diff_words_data(struct emit_callback *ecbdata)
 {
        if (ecbdata->diff_words) {
                diff_words_flush(ecbdata);
+               free (ecbdata->diff_words->opt);
                free (ecbdata->diff_words->minus.text.ptr);
                free (ecbdata->diff_words->minus.orig);
                free (ecbdata->diff_words->plus.text.ptr);
@@ -1324,12 +1400,59 @@ static void fill_print_name(struct diffstat_file *file)
        file->print_name = pname;
 }
 
+int print_stat_summary(FILE *fp, int files, int insertions, int deletions)
+{
+       struct strbuf sb = STRBUF_INIT;
+       int ret;
+
+       if (!files) {
+               assert(insertions == 0 && deletions == 0);
+               return fprintf(fp, "%s\n", " 0 files changed");
+       }
+
+       strbuf_addf(&sb,
+                   (files == 1) ? " %d file changed" : " %d files changed",
+                   files);
+
+       /*
+        * For binary diff, the caller may want to print "x files
+        * changed" with insertions == 0 && deletions == 0.
+        *
+        * Not omitting "0 insertions(+), 0 deletions(-)" in this case
+        * is probably less confusing (i.e skip over "2 files changed
+        * but nothing about added/removed lines? Is this a bug in Git?").
+        */
+       if (insertions || deletions == 0) {
+               /*
+                * TRANSLATORS: "+" in (+) is a line addition marker;
+                * do not translate it.
+                */
+               strbuf_addf(&sb,
+                           (insertions == 1) ? ", %d insertion(+)" : ", %d insertions(+)",
+                           insertions);
+       }
+
+       if (deletions || insertions == 0) {
+               /*
+                * TRANSLATORS: "-" in (-) is a line removal marker;
+                * do not translate it.
+                */
+               strbuf_addf(&sb,
+                           (deletions == 1) ? ", %d deletion(-)" : ", %d deletions(-)",
+                           deletions);
+       }
+       strbuf_addch(&sb, '\n');
+       ret = fputs(sb.buf, fp);
+       strbuf_release(&sb);
+       return ret;
+}
+
 static void show_stats(struct diffstat_t *data, struct diff_options *options)
 {
        int i, len, add, del, adds = 0, dels = 0;
        uintmax_t max_change = 0, max_len = 0;
-       int total_files = data->nr;
-       int width, name_width, graph_width, number_width = 4, count;
+       int total_files = data->nr, count;
+       int width, name_width, graph_width, number_width = 0, bin_width = 0;
        const char *reset, *add_c, *del_c;
        const char *line_prefix = "";
        int extra_shown = 0;
@@ -1365,8 +1488,21 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                if (max_len < len)
                        max_len = len;
 
-               if (file->is_binary || file->is_unmerged)
+               if (file->is_unmerged) {
+                       /* "Unmerged" is 8 characters */
+                       bin_width = bin_width < 8 ? 8 : bin_width;
+                       continue;
+               }
+               if (file->is_binary) {
+                       /* "Bin XXX -> YYY bytes" */
+                       int w = 14 + decimal_width(file->added)
+                               + decimal_width(file->deleted);
+                       bin_width = bin_width < w ? w : bin_width;
+                       /* Display change counts aligned with "Bin" */
+                       number_width = 3;
                        continue;
+               }
+
                if (max_change < change)
                        max_change = change;
        }
@@ -1391,12 +1527,25 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
         * stat_name_width fixes the maximum width of the filename,
         * and is also used to divide available columns if there
         * aren't enough.
+        *
+        * Binary files are displayed with "Bin XXX -> YYY bytes"
+        * instead of the change count and graph. This part is treated
+        * similarly to the graph part, except that it is not
+        * "scaled". If total width is too small to accomodate the
+        * guaranteed minimum width of the filename part and the
+        * separators and this message, this message will "overflow"
+        * making the line longer than the maximum width.
         */
 
        if (options->stat_width == -1)
-               width = term_columns();
+               width = term_columns() - options->output_prefix_length;
        else
                width = options->stat_width ? options->stat_width : 80;
+       number_width = decimal_width(max_change) > number_width ?
+               decimal_width(max_change) : number_width;
+
+       if (options->stat_graph_width == -1)
+               options->stat_graph_width = diff_stat_graph_width;
 
        /*
         * Guarantee 3/8*16==6 for the graph part
@@ -1407,10 +1556,14 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 
        /*
         * First assign sizes that are wanted, ignoring available width.
+        * strlen("Bin XXX -> YYY bytes") == bin_width, and the part
+        * starting from "XXX" should fit in graph_width.
         */
-       graph_width = (options->stat_graph_width &&
-                      options->stat_graph_width < max_change) ?
-               options->stat_graph_width : max_change;
+       graph_width = max_change + 4 > bin_width ? max_change : bin_width - 4;
+       if (options->stat_graph_width &&
+           options->stat_graph_width < graph_width)
+               graph_width = options->stat_graph_width;
+
        name_width = (options->stat_name_width > 0 &&
                      options->stat_name_width < max_len) ?
                options->stat_name_width : max_len;
@@ -1419,8 +1572,12 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
         * Adjust adjustable widths not to exceed maximum width
         */
        if (name_width + number_width + 6 + graph_width > width) {
-               if (graph_width > width * 3/8 - number_width - 6)
+               if (graph_width > width * 3/8 - number_width - 6) {
                        graph_width = width * 3/8 - number_width - 6;
+                       if (graph_width < 6)
+                               graph_width = 6;
+               }
+
                if (options->stat_graph_width &&
                    graph_width > options->stat_graph_width)
                        graph_width = options->stat_graph_width;
@@ -1465,8 +1622,12 @@ 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%"PRIuMAX"%s",
+                       fprintf(options->file, " %*s", number_width, "Bin");
+                       if (!added && !deleted) {
+                               putc('\n', options->file);
+                               continue;
+                       }
+                       fprintf(options->file, " %s%"PRIuMAX"%s",
                                del_c, deleted, reset);
                        fprintf(options->file, " -> ");
                        fprintf(options->file, "%s%"PRIuMAX"%s",
@@ -1478,7 +1639,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                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");
+                       fprintf(options->file, " Unmerged\n");
                        continue;
                }
 
@@ -1507,8 +1668,9 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                }
                fprintf(options->file, "%s", line_prefix);
                show_name(options->file, prefix, name, len);
-               fprintf(options->file, "%5"PRIuMAX"%s", added + deleted,
-                               added + deleted ? " " : "");
+               fprintf(options->file, " %*"PRIuMAX"%s",
+                       number_width, added + deleted,
+                       added + deleted ? " " : "");
                show_graph(options->file, '+', add, add_c, reset);
                show_graph(options->file, '-', del, del_c, reset);
                fprintf(options->file, "\n");
@@ -1528,9 +1690,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                extra_shown = 1;
        }
        fprintf(options->file, "%s", line_prefix);
-       fprintf(options->file,
-              " %d files changed, %d insertions(+), %d deletions(-)\n",
-              total_files, adds, dels);
+       print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_shortstats(struct diffstat_t *data, struct diff_options *options)
@@ -1541,17 +1701,16 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
                return;
 
        for (i = 0; i < data->nr; i++) {
-               if (!data->files[i]->is_binary &&
-                   !data->files[i]->is_unmerged) {
-                       int added = data->files[i]->added;
-                       int deleted= data->files[i]->deleted;
-                       if (!data->files[i]->is_renamed &&
-                           (added + deleted == 0)) {
-                               total_files--;
-                       } else {
-                               adds += added;
-                               dels += deleted;
-                       }
+               int added = data->files[i]->added;
+               int deleted= data->files[i]->deleted;
+
+               if (data->files[i]->is_unmerged)
+                       continue;
+               if (!data->files[i]->is_renamed && (added + deleted == 0)) {
+                       total_files--;
+               } else if (!data->files[i]->is_binary) { /* don't count bytes */
+                       adds += added;
+                       dels += deleted;
                }
        }
        if (options->output_prefix) {
@@ -1560,8 +1719,7 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
                                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);
+       print_stat_summary(options->file, total_files, adds, dels);
 }
 
 static void show_numstat(struct diffstat_t *data, struct diff_options *options)
@@ -2010,20 +2168,6 @@ static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *pre
        emit_binary_diff_body(file, two, one, prefix);
 }
 
-static void diff_filespec_load_driver(struct diff_filespec *one)
-{
-       /* Use already-loaded driver */
-       if (one->driver)
-               return;
-
-       if (S_ISREG(one->mode))
-               one->driver = userdiff_find_by_path(one->path);
-
-       /* Fallback to default settings */
-       if (!one->driver)
-               one->driver = userdiff_find_by_name("default");
-}
-
 int diff_filespec_is_binary(struct diff_filespec *one)
 {
        if (one->is_binary == -1) {
@@ -2049,12 +2193,6 @@ static const struct userdiff_funcname *diff_funcname_pattern(struct diff_filespe
        return one->driver->funcname.pattern ? &one->driver->funcname : NULL;
 }
 
-static const char *userdiff_word_regex(struct diff_filespec *one)
-{
-       diff_filespec_load_driver(one);
-       return one->driver->word_regex;
-}
-
 void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
 {
        if (!options->a_prefix)
@@ -2204,7 +2342,7 @@ static void builtin_diff(const char *name_a,
                struct emit_callback ecbdata;
                const struct userdiff_funcname *pe;
 
-               if (!DIFF_XDL_TST(o, WHITESPACE_FLAGS) || must_show_header) {
+               if (must_show_header) {
                        fprintf(o->file, "%s", header.buf);
                        strbuf_reset(&header);
                }
@@ -2241,42 +2379,8 @@ 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 (o->word_diff) {
-                       int i;
-
-                       ecbdata.diff_words =
-                               xcalloc(1, sizeof(struct diff_words_data));
-                       ecbdata.diff_words->type = o->word_diff;
-                       ecbdata.diff_words->opt = o;
-                       if (!o->word_regex)
-                               o->word_regex = userdiff_word_regex(one);
-                       if (!o->word_regex)
-                               o->word_regex = userdiff_word_regex(two);
-                       if (!o->word_regex)
-                               o->word_regex = diff_word_regex_cfg;
-                       if (o->word_regex) {
-                               ecbdata.diff_words->word_regex = (regex_t *)
-                                       xmalloc(sizeof(regex_t));
-                               if (regcomp(ecbdata.diff_words->word_regex,
-                                               o->word_regex,
-                                               REG_EXTENDED | REG_NEWLINE))
-                                       die ("Invalid regular expression: %s",
-                                                       o->word_regex);
-                       }
-                       for (i = 0; i < ARRAY_SIZE(diff_words_styles); i++) {
-                               if (o->word_diff == diff_words_styles[i].type) {
-                                       ecbdata.diff_words->style =
-                                               &diff_words_styles[i];
-                                       break;
-                               }
-                       }
-                       if (want_color(o->use_color)) {
-                               struct diff_words_style *st = ecbdata.diff_words->style;
-                               st->old.color = diff_get_color_opt(o, DIFF_FILE_OLD);
-                               st->new.color = diff_get_color_opt(o, DIFF_FILE_NEW);
-                               st->ctx.color = diff_get_color_opt(o, DIFF_PLAIN);
-                       }
-               }
+               if (o->word_diff)
+                       init_diff_words_data(&ecbdata, o, one, two);
                xdi_diff_outf(&mf1, &mf2, fn_out_consume, &ecbdata,
                              &xpp, &xecfg);
                if (o->word_diff)
@@ -2306,6 +2410,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
 {
        mmfile_t mf1, mf2;
        struct diffstat_file *data;
+       int same_contents;
 
        data = diffstat_add(diffstat, name_a, name_b);
 
@@ -2314,10 +2419,17 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                return;
        }
 
+       same_contents = !hashcmp(one->sha1, two->sha1);
+
        if (diff_filespec_is_binary(one) || diff_filespec_is_binary(two)) {
                data->is_binary = 1;
-               data->added = diff_filespec_size(two);
-               data->deleted = diff_filespec_size(one);
+               if (same_contents) {
+                       data->added = 0;
+                       data->deleted = 0;
+               } else {
+                       data->added = diff_filespec_size(two);
+                       data->deleted = diff_filespec_size(one);
+               }
        }
 
        else if (complete_rewrite) {
@@ -2327,7 +2439,7 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                data->added = count_lines(two->data, two->size);
        }
 
-       else {
+       else if (!same_contents) {
                /* Crazy xdl interfaces.. */
                xpparam_t xpp;
                xdemitconf_t xecfg;
@@ -2437,12 +2549,12 @@ void free_filespec(struct diff_filespec *spec)
 }
 
 void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
-                  unsigned short mode)
+                  int sha1_valid, unsigned short mode)
 {
        if (mode) {
                spec->mode = canon_mode(mode);
                hashcpy(spec->sha1, sha1);
-               spec->sha1_valid = !is_null_sha1(sha1);
+               spec->sha1_valid = sha1_valid;
        }
 }
 
@@ -2515,22 +2627,6 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int
        return 0;
 }
 
-static int populate_from_stdin(struct diff_filespec *s)
-{
-       struct strbuf buf = STRBUF_INIT;
-       size_t size = 0;
-
-       if (strbuf_read(&buf, 0, 0) < 0)
-               return error("error while reading from stdin %s",
-                                    strerror(errno));
-
-       s->should_munmap = 0;
-       s->data = strbuf_detach(&buf, &size);
-       s->size = size;
-       s->should_free = 1;
-       return 0;
-}
-
 static int diff_populate_gitlink(struct diff_filespec *s, int size_only)
 {
        int len;
@@ -2580,9 +2676,6 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only)
                struct stat st;
                int fd;
 
-               if (!strcmp(s->path, "-"))
-                       return populate_from_stdin(s);
-
                if (lstat(s->path, &st) < 0) {
                        if (errno == ENOENT) {
                        err_empty:
@@ -2907,9 +3000,8 @@ static void run_diff_cmd(const char *pgm,
        int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
        int must_show_header = 0;
 
-       if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
-               pgm = NULL;
-       else {
+
+       if (DIFF_OPT_TST(o, ALLOW_EXTERNAL)) {
                struct userdiff_driver *drv = userdiff_find_by_path(attr_path);
                if (drv && drv->external)
                        pgm = drv->external;
@@ -2944,7 +3036,7 @@ static void diff_fill_sha1_info(struct diff_filespec *one)
        if (DIFF_FILE_VALID(one)) {
                if (!one->sha1_valid) {
                        struct stat st;
-                       if (!strcmp(one->path, "-")) {
+                       if (one->is_stdin) {
                                hashcpy(one->sha1, null_sha1);
                                return;
                        }
@@ -2989,6 +3081,9 @@ static void run_diff(struct diff_filepair *p, struct diff_options *o)
        if (o->prefix_length)
                strip_prefix(o->prefix_length, &name, &other);
 
+       if (!DIFF_OPT_TST(o, ALLOW_EXTERNAL))
+               pgm = NULL;
+
        if (DIFF_PAIR_UNMERGED(p)) {
                run_diff_cmd(pgm, name, NULL, attr_path,
                             NULL, NULL, NULL, o, p);
@@ -3084,7 +3179,8 @@ void diff_setup(struct diff_options *options)
        options->break_opt = -1;
        options->rename_limit = -1;
        options->dirstat_permille = diff_dirstat_permille_default;
-       options->context = 3;
+       options->context = diff_context_default;
+       DIFF_OPT_SET(options, RENAME_EMPTY);
 
        options->change = diff_change;
        options->add_remove = diff_addremove;
@@ -3099,7 +3195,7 @@ void diff_setup(struct diff_options *options)
        }
 }
 
-int diff_setup_done(struct diff_options *options)
+void diff_setup_done(struct diff_options *options)
 {
        int count = 0;
 
@@ -3198,8 +3294,6 @@ int diff_setup_done(struct diff_options *options)
                options->output_format = DIFF_FORMAT_NO_OUTPUT;
                DIFF_OPT_SET(options, EXIT_WITH_STATUS);
        }
-
-       return 0;
 }
 
 static int opt_arg(const char *arg, int arg_short, const char *arg_long, int *val)
@@ -3455,6 +3549,10 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        }
        else if (!strcmp(arg, "--no-renames"))
                options->detect_rename = 0;
+       else if (!strcmp(arg, "--rename-empty"))
+               DIFF_OPT_SET(options, RENAME_EMPTY);
+       else if (!strcmp(arg, "--no-rename-empty"))
+               DIFF_OPT_CLR(options, RENAME_EMPTY);
        else if (!strcmp(arg, "--relative"))
                DIFF_OPT_SET(options, RELATIVE_NAME);
        else if (!prefixcmp(arg, "--relative=")) {
@@ -3474,9 +3572,9 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
        else if (!strcmp(arg, "--ignore-space-at-eol"))
                DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL);
        else if (!strcmp(arg, "--patience"))
-               DIFF_XDL_SET(options, PATIENCE_DIFF);
+               options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
        else if (!strcmp(arg, "--histogram"))
-               DIFF_XDL_SET(options, HISTOGRAM_DIFF);
+               options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
 
        /* flags options */
        else if (!strcmp(arg, "--binary")) {
@@ -4348,6 +4446,12 @@ void diff_flush(struct diff_options *options)
 
        if (output_format & DIFF_FORMAT_PATCH) {
                if (separator) {
+                       if (options->output_prefix) {
+                               struct strbuf *msg = NULL;
+                               msg = options->output_prefix(options,
+                                       options->output_prefix_data);
+                               fwrite(msg->buf, msg->len, 1, stdout);
+                       }
                        putc(options->line_termination, options->file);
                        if (options->stat_sep) {
                                /* attach patch instead of inline */
@@ -4595,6 +4699,7 @@ static int is_submodule_ignored(const char *path, struct diff_options *options)
 void diff_addremove(struct diff_options *options,
                    int addremove, unsigned mode,
                    const unsigned char *sha1,
+                   int sha1_valid,
                    const char *concatpath, unsigned dirty_submodule)
 {
        struct diff_filespec *one, *two;
@@ -4626,9 +4731,9 @@ void diff_addremove(struct diff_options *options,
        two = alloc_filespec(concatpath);
 
        if (addremove != '+')
-               fill_filespec(one, sha1, mode);
+               fill_filespec(one, sha1, sha1_valid, mode);
        if (addremove != '-') {
-               fill_filespec(two, sha1, mode);
+               fill_filespec(two, sha1, sha1_valid, mode);
                two->dirty_submodule = dirty_submodule;
        }
 
@@ -4641,6 +4746,7 @@ void diff_change(struct diff_options *options,
                 unsigned old_mode, unsigned new_mode,
                 const unsigned char *old_sha1,
                 const unsigned char *new_sha1,
+                int old_sha1_valid, int new_sha1_valid,
                 const char *concatpath,
                 unsigned old_dirty_submodule, unsigned new_dirty_submodule)
 {
@@ -4655,6 +4761,8 @@ void diff_change(struct diff_options *options,
                const unsigned char *tmp_c;
                tmp = old_mode; old_mode = new_mode; new_mode = tmp;
                tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
+               tmp = old_sha1_valid; old_sha1_valid = new_sha1_valid;
+                       new_sha1_valid = tmp;
                tmp = old_dirty_submodule; old_dirty_submodule = new_dirty_submodule;
                        new_dirty_submodule = tmp;
        }
@@ -4665,8 +4773,8 @@ void diff_change(struct diff_options *options,
 
        one = alloc_filespec(concatpath);
        two = alloc_filespec(concatpath);
-       fill_filespec(one, old_sha1, old_mode);
-       fill_filespec(two, new_sha1, new_mode);
+       fill_filespec(one, old_sha1, old_sha1_valid, old_mode);
+       fill_filespec(two, new_sha1, new_sha1_valid, new_mode);
        one->dirty_submodule = old_dirty_submodule;
        two->dirty_submodule = new_dirty_submodule;
 
@@ -4772,3 +4880,19 @@ size_t fill_textconv(struct userdiff_driver *driver,
 
        return size;
 }
+
+void setup_diff_pager(struct diff_options *opt)
+{
+       /*
+        * If the user asked for our exit code, then either they want --quiet
+        * or --exit-code. We should definitely not bother with a pager in the
+        * former case, as we will generate no output. Since we still properly
+        * report our exit code even when a pager is run, we _could_ run a
+        * pager with --exit-code. But since we have not done so historically,
+        * and because it is easy to find people oneline advising "git diff
+        * --exit-code" in hooks and other scripts, we do not do so.
+        */
+       if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
+           check_pager_config("diff") != 0)
+               setup_pager();
+}