Merge branch 'jc/maint-diff-core-safecrlf' into maint
[git/git.git] / diff.c
diff --git a/diff.c b/diff.c
index 3e406f1..71e4df9 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
@@ -25,7 +26,8 @@
 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;
@@ -34,6 +36,7 @@ static int diff_no_prefix;
 static int diff_stat_graph_width;
 static int diff_dirstat_permille_default = 30;
 static struct diff_options default_diff_options;
+static long diff_algorithm;
 
 static char diff_colors[][COLOR_MAXLEN] = {
        GIT_COLOR_RESET,
@@ -68,26 +71,30 @@ 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;
@@ -99,27 +106,35 @@ 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;
 }
 
+static int parse_submodule_params(struct diff_options *options, const char *value)
+{
+       if (!strcmp(value, "log"))
+               DIFF_OPT_SET(options, SUBMODULE_LOG);
+       else if (!strcmp(value, "short"))
+               DIFF_OPT_CLR(options, SUBMODULE_LOG);
+       else
+               return -1;
+       return 0;
+}
+
 static int git_config_rename(const char *var, const char *value)
 {
        if (!value)
@@ -129,6 +144,21 @@ static int git_config_rename(const char *var, const char *value)
        return git_config_bool(var,value) ? DIFF_DETECT_RENAME : 0;
 }
 
+long parse_algorithm_value(const char *value)
+{
+       if (!value)
+               return -1;
+       else if (!strcasecmp(value, "myers") || !strcasecmp(value, "default"))
+               return 0;
+       else if (!strcasecmp(value, "minimal"))
+               return XDF_NEED_MINIMAL;
+       else if (!strcasecmp(value, "patience"))
+               return XDF_PATIENCE_DIFF;
+       else if (!strcasecmp(value, "histogram"))
+               return XDF_HISTOGRAM_DIFF;
+       return -1;
+}
+
 /*
  * These are to give UI layer defaults.
  * The core-level commands such as git-diff-files should
@@ -141,6 +171,12 @@ 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;
@@ -169,6 +205,20 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
        if (!strcmp(var, "diff.ignoresubmodules"))
                handle_ignore_submodules_arg(&default_diff_options, value);
 
+       if (!strcmp(var, "diff.submodule")) {
+               if (parse_submodule_params(&default_diff_options, value))
+                       warning(_("Unknown value for 'diff.submodule' config variable: '%s'"),
+                               value);
+               return 0;
+       }
+
+       if (!strcmp(var, "diff.algorithm")) {
+               diff_algorithm = parse_algorithm_value(value);
+               if (diff_algorithm < 0)
+                       return -1;
+               return 0;
+       }
+
        if (git_color_config(var, value, cb) < 0)
                return -1;
 
@@ -375,12 +425,7 @@ static void emit_line_0(struct diff_options *o, const char *set, const char *res
        int nofirst;
        FILE *file = o->file;
 
-       if (o->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = o->output_prefix(o, o->output_prefix_data);
-               assert(msg);
-               fwrite(msg->buf, msg->len, 1, file);
-       }
+       fputs(diff_line_prefix(o), file);
 
        if (len == 0) {
                has_trailing_newline = (first == '\n');
@@ -598,13 +643,7 @@ static void emit_rewrite_diff(const char *name_a,
        char *data_one, *data_two;
        size_t size_one, size_two;
        struct emit_callback ecbdata;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
-
-       if (o && o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
                a_prefix = o->b_prefix;
@@ -800,18 +839,14 @@ static void fn_out_diff_words_aux(void *priv, char *line, unsigned long len)
        int minus_first, minus_len, plus_first, plus_len;
        const char *minus_begin, *minus_end, *plus_begin, *plus_end;
        struct diff_options *opt = diff_words->opt;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix;
 
        if (line[0] != '@' || parse_hunk_header(line, len,
                        &minus_first, &minus_len, &plus_first, &plus_len))
                return;
 
        assert(opt);
-       if (opt->output_prefix) {
-               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(opt);
 
        /* POSIX requires that first be decremented by one if len == 0... */
        if (minus_len) {
@@ -935,14 +970,10 @@ static void diff_words_show(struct diff_words_data *diff_words)
        struct diff_words_style *style = diff_words->style;
 
        struct diff_options *opt = diff_words->opt;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix;
 
        assert(opt);
-       if (opt->output_prefix) {
-               msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(opt);
 
        /* special case: only removal */
        if (!diff_words->plus.text.size) {
@@ -1078,6 +1109,16 @@ const char *diff_get_color(int diff_use_color, enum color_diff ix)
        return "";
 }
 
+const char *diff_line_prefix(struct diff_options *opt)
+{
+       struct strbuf *msgbuf;
+       if (!opt->output_prefix)
+               return "";
+
+       msgbuf = opt->output_prefix(opt, opt->output_prefix_data);
+       return msgbuf->buf;
+}
+
 static unsigned long sane_truncate_line(struct emit_callback *ecb, char *line, unsigned long len)
 {
        const char *cp;
@@ -1118,13 +1159,7 @@ static void fn_out_consume(void *priv, char *line, unsigned long len)
        const char *plain = diff_get_color(ecbdata->color_diff, DIFF_PLAIN);
        const char *reset = diff_get_color(ecbdata->color_diff, DIFF_RESET);
        struct diff_options *o = ecbdata->opt;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
-
-       if (o && o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (ecbdata->header) {
                fprintf(ecbdata->opt->file, "%s", ecbdata->header->buf);
@@ -1229,6 +1264,7 @@ static char *pprint_rename(const char *a, const char *b)
        const char *new = b;
        struct strbuf name = STRBUF_INIT;
        int pfx_length, sfx_length;
+       int pfx_adjust_for_slash;
        int len_a = strlen(a);
        int len_b = strlen(b);
        int a_midlen, b_midlen;
@@ -1255,7 +1291,18 @@ static char *pprint_rename(const char *a, const char *b)
        old = a + len_a;
        new = b + len_b;
        sfx_length = 0;
-       while (a <= old && b <= new && *old == *new) {
+       /*
+        * If there is a common prefix, it must end in a slash.  In
+        * that case we let this loop run 1 into the prefix to see the
+        * same slash.
+        *
+        * If there is no common prefix, we cannot do this as it would
+        * underrun the input strings.
+        */
+       pfx_adjust_for_slash = (pfx_length ? 1 : 0);
+       while (a + pfx_length - pfx_adjust_for_slash <= old &&
+              b + pfx_length - pfx_adjust_for_slash <= new &&
+              *old == *new) {
                if (*old == '/')
                        sfx_length = len_a - (old - a);
                old--;
@@ -1300,6 +1347,7 @@ struct diffstat_t {
                unsigned is_unmerged:1;
                unsigned is_binary:1;
                unsigned is_renamed:1;
+               unsigned is_interesting:1;
                uintmax_t added, deleted;
        } **files;
 };
@@ -1447,16 +1495,11 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
        const char *reset, *add_c, *del_c;
        const char *line_prefix = "";
        int extra_shown = 0;
-       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;
-       }
-
+       line_prefix = diff_line_prefix(options);
        count = options->stat_count ? options->stat_count : data->nr;
 
        reset = diff_get_color_opt(options, DIFF_RESET);
@@ -1469,8 +1512,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
        for (i = 0; (i < count) && (i < data->nr); i++) {
                struct diffstat_file *file = data->files[i];
                uintmax_t change = file->added + file->deleted;
-               if (!data->files[i]->is_renamed &&
-                        (change == 0)) {
+
+               if (!file->is_interesting && (change == 0)) {
                        count++; /* not shown == room for one more */
                        continue;
                }
@@ -1497,7 +1540,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                if (max_change < change)
                        max_change = change;
        }
-       count = i; /* min(count, data->nr) */
+       count = i; /* where we can stop scanning in data->files[] */
 
        /*
         * We have width = stat_width or term_columns() columns total.
@@ -1522,7 +1565,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
         * 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
+        * "scaled". If total width is too small to accommodate the
         * guaranteed minimum width of the filename part and the
         * separators and this message, this message will "overflow"
         * making the line longer than the maximum width.
@@ -1585,16 +1628,15 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
         */
        for (i = 0; i < count; i++) {
                const char *prefix = "";
-               char *name = data->files[i]->print_name;
-               uintmax_t added = data->files[i]->added;
-               uintmax_t deleted = data->files[i]->deleted;
+               struct diffstat_file *file = data->files[i];
+               char *name = file->print_name;
+               uintmax_t added = file->added;
+               uintmax_t deleted = file->deleted;
                int name_len;
 
-               if (!data->files[i]->is_renamed &&
-                        (added + deleted == 0)) {
-                       total_files--;
+               if (!file->is_interesting && (added + deleted == 0))
                        continue;
-               }
+
                /*
                 * "scale" the filename
                 */
@@ -1610,7 +1652,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                                name = slash;
                }
 
-               if (data->files[i]->is_binary) {
+               if (file->is_binary) {
                        fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, " %*s", number_width, "Bin");
@@ -1627,7 +1669,7 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                        fprintf(options->file, "\n");
                        continue;
                }
-               else if (data->files[i]->is_unmerged) {
+               else if (file->is_unmerged) {
                        fprintf(options->file, "%s", line_prefix);
                        show_name(options->file, prefix, name, len);
                        fprintf(options->file, " Unmerged\n");
@@ -1639,8 +1681,6 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                 */
                add = added;
                del = deleted;
-               adds += add;
-               dels += del;
 
                if (graph_width <= max_change) {
                        int total = add + del;
@@ -1666,16 +1706,24 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
                show_graph(options->file, '-', del, del_c, reset);
                fprintf(options->file, "\n");
        }
-       for (i = count; i < data->nr; i++) {
-               uintmax_t added = data->files[i]->added;
-               uintmax_t deleted = data->files[i]->deleted;
-               if (!data->files[i]->is_renamed &&
-                        (added + deleted == 0)) {
+
+       for (i = 0; i < data->nr; i++) {
+               struct diffstat_file *file = data->files[i];
+               uintmax_t added = file->added;
+               uintmax_t deleted = file->deleted;
+
+               if (file->is_unmerged ||
+                   (!file->is_interesting && (added + deleted == 0))) {
                        total_files--;
                        continue;
                }
-               adds += added;
-               dels += deleted;
+
+               if (!file->is_binary) {
+                       adds += added;
+                       dels += deleted;
+               }
+               if (i < count)
+                       continue;
                if (!extra_shown)
                        fprintf(options->file, "%s ...\n", line_prefix);
                extra_shown = 1;
@@ -1695,21 +1743,15 @@ static void show_shortstats(struct diffstat_t *data, struct diff_options *option
                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)) {
+               if (data->files[i]->is_unmerged ||
+                   (!data->files[i]->is_interesting && (added + deleted == 0))) {
                        total_files--;
                } else if (!data->files[i]->is_binary) { /* don't count bytes */
                        adds += added;
                        dels += deleted;
                }
        }
-       if (options->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = options->output_prefix(options,
-                               options->output_prefix_data);
-               fprintf(options->file, "%s", msg->buf);
-       }
+       fprintf(options->file, "%s", diff_line_prefix(options));
        print_stat_summary(options->file, total_files, adds, dels);
 }
 
@@ -1723,12 +1765,7 @@ static void show_numstat(struct diffstat_t *data, struct diff_options *options)
        for (i = 0; i < data->nr; i++) {
                struct diffstat_file *file = data->files[i];
 
-               if (options->output_prefix) {
-                       struct strbuf *msg = NULL;
-                       msg = options->output_prefix(options,
-                                       options->output_prefix_data);
-                       fprintf(options->file, "%s", msg->buf);
-               }
+               fprintf(options->file, "%s", diff_line_prefix(options));
 
                if (file->is_binary)
                        fprintf(options->file, "-\t-\t");
@@ -1770,13 +1807,7 @@ static long gather_dirstat(struct diff_options *opt, struct dirstat_dir *dir,
 {
        unsigned long this_dir = 0;
        unsigned int sources = 0;
-       const char *line_prefix = "";
-       struct strbuf *msg = NULL;
-
-       if (opt->output_prefix) {
-               msg = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = msg->buf;
-       }
+       const char *line_prefix = diff_line_prefix(opt);
 
        while (dir->nr) {
                struct dirstat_file *f = dir->files;
@@ -2026,15 +2057,10 @@ static void checkdiff_consume(void *priv, char *line, unsigned long len)
        const char *reset = diff_get_color(data->o->use_color, DIFF_RESET);
        const char *set = diff_get_color(data->o->use_color, DIFF_FILE_NEW);
        char *err;
-       char *line_prefix = "";
-       struct strbuf *msgbuf;
+       const char *line_prefix;
 
        assert(data->o);
-       if (data->o->output_prefix) {
-               msgbuf = data->o->output_prefix(data->o,
-                       data->o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       line_prefix = diff_line_prefix(data->o);
 
        if (line[0] == '+') {
                unsigned bad;
@@ -2091,7 +2117,8 @@ static unsigned char *deflate_it(char *data,
        return deflated;
 }
 
-static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two,
+                                 const char *prefix)
 {
        void *cp;
        void *delta;
@@ -2152,7 +2179,8 @@ static void emit_binary_diff_body(FILE *file, mmfile_t *one, mmfile_t *two, char
        free(data);
 }
 
-static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two, char *prefix)
+static void emit_binary_diff(FILE *file, mmfile_t *one, mmfile_t *two,
+                            const char *prefix)
 {
        fprintf(file, "%sGIT binary patch\n", prefix);
        emit_binary_diff_body(file, one, two, prefix);
@@ -2213,19 +2241,13 @@ static void builtin_diff(const char *name_a,
        mmfile_t mf1, mf2;
        const char *lbl[2];
        char *a_one, *b_two;
-       const char *set = diff_get_color_opt(o, DIFF_METAINFO);
+       const char *meta = diff_get_color_opt(o, DIFF_METAINFO);
        const char *reset = diff_get_color_opt(o, DIFF_RESET);
        const char *a_prefix, *b_prefix;
        struct userdiff_driver *textconv_one = NULL;
        struct userdiff_driver *textconv_two = NULL;
        struct strbuf header = STRBUF_INIT;
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
-
-       if (o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(o);
 
        if (DIFF_OPT_TST(o, SUBMODULE_LOG) &&
                        (!one->mode || S_ISGITLINK(one->mode)) &&
@@ -2233,8 +2255,9 @@ static void builtin_diff(const char *name_a,
                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,
+                               line_prefix,
                                one->sha1, two->sha1, two->dirty_submodule,
-                               del, add, reset);
+                               meta, del, add, reset);
                return;
        }
 
@@ -2260,24 +2283,24 @@ static void builtin_diff(const char *name_a,
        b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
        lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
        lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
-       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, set, a_one, b_two, reset);
+       strbuf_addf(&header, "%s%sdiff --git %s %s%s\n", line_prefix, meta, a_one, b_two, reset);
        if (lbl[0][0] == '/') {
                /* /dev/null */
-               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, set, two->mode, reset);
+               strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
-               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, set, one->mode, reset);
+               strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
                must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
-                       strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, set, one->mode, reset);
-                       strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, set, two->mode, reset);
+                       strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
+                       strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
                        must_show_header = 1;
                }
                if (xfrm_msg)
@@ -2397,13 +2420,20 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
                             struct diff_filespec *two,
                             struct diffstat_t *diffstat,
                             struct diff_options *o,
-                            int complete_rewrite)
+                            struct diff_filepair *p)
 {
        mmfile_t mf1, mf2;
        struct diffstat_file *data;
        int same_contents;
+       int complete_rewrite = 0;
+
+       if (!DIFF_PAIR_UNMERGED(p)) {
+               if (p->status == DIFF_STATUS_MODIFIED && p->score)
+                       complete_rewrite = 1;
+       }
 
        data = diffstat_add(diffstat, name_a, name_b);
+       data->is_interesting = p->status != DIFF_STATUS_UNKNOWN;
 
        if (!one || !two) {
                data->is_unmerged = 1;
@@ -2925,14 +2955,9 @@ static void fill_metainfo(struct strbuf *msg,
 {
        const char *set = diff_get_color(use_color, DIFF_METAINFO);
        const char *reset = diff_get_color(use_color, DIFF_RESET);
-       struct strbuf *msgbuf;
-       char *line_prefix = "";
+       const char *line_prefix = diff_line_prefix(o);
 
        *must_show_header = 1;
-       if (o->output_prefix) {
-               msgbuf = o->output_prefix(o, o->output_prefix_data);
-               line_prefix = msgbuf->buf;
-       }
        strbuf_init(msg, PATH_MAX * 2 + 300);
        switch (p->status) {
        case DIFF_STATUS_COPIED:
@@ -3122,11 +3147,10 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
 {
        const char *name;
        const char *other;
-       int complete_rewrite = 0;
 
        if (DIFF_PAIR_UNMERGED(p)) {
                /* unmerged */
-               builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, 0);
+               builtin_diffstat(p->one->path, NULL, NULL, NULL, diffstat, o, p);
                return;
        }
 
@@ -3139,9 +3163,7 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
        diff_fill_sha1_info(p->one);
        diff_fill_sha1_info(p->two);
 
-       if (p->status == DIFF_STATUS_MODIFIED && p->score)
-               complete_rewrite = 1;
-       builtin_diffstat(name, other, p->one, p->two, diffstat, o, complete_rewrite);
+       builtin_diffstat(name, other, p->one, p->two, diffstat, o, p);
 }
 
 static void run_checkdiff(struct diff_filepair *p, struct diff_options *o)
@@ -3178,13 +3200,14 @@ 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;
        options->use_color = diff_use_color_default;
        options->detect_rename = diff_detect_rename_default;
+       options->xdl_opts |= diff_algorithm;
 
        if (diff_no_prefix) {
                options->a_prefix = options->b_prefix = "";
@@ -3474,6 +3497,14 @@ static int parse_dirstat_opt(struct diff_options *options, const char *params)
        return 1;
 }
 
+static int parse_submodule_opt(struct diff_options *options, const char *value)
+{
+       if (parse_submodule_params(options, value))
+               die(_("Failed to parse --submodule option parameter: '%s'"),
+                       value);
+       return 1;
+}
+
 int diff_opt_parse(struct diff_options *options, const char **av, int ac)
 {
        const char *arg = av[0];
@@ -3574,6 +3605,17 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
        else if (!strcmp(arg, "--histogram"))
                options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
+       else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
+               long value = parse_algorithm_value(optarg);
+               if (value < 0)
+                       return error("option diff-algorithm accepts \"myers\", "
+                                    "\"minimal\", \"patience\" and \"histogram\"");
+               /* clear out previous settings */
+               DIFF_XDL_CLR(options, NEED_MINIMAL);
+               options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
+               options->xdl_opts |= value;
+               return argcount;
+       }
 
        /* flags options */
        else if (!strcmp(arg, "--binary")) {
@@ -3590,6 +3632,8 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                DIFF_OPT_SET(options, FIND_COPIES_HARDER);
        else if (!strcmp(arg, "--follow"))
                DIFF_OPT_SET(options, FOLLOW_RENAMES);
+       else if (!strcmp(arg, "--no-follow"))
+               DIFF_OPT_CLR(options, FOLLOW_RENAMES);
        else if (!strcmp(arg, "--color"))
                options->use_color = 1;
        else if (!prefixcmp(arg, "--color=")) {
@@ -3654,10 +3698,8 @@ int diff_opt_parse(struct diff_options *options, const char **av, int ac)
                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);
-       }
+       else if (!prefixcmp(arg, "--submodule="))
+               return parse_submodule_opt(options, arg + 12);
 
        /* misc options */
        else if (!strcmp(arg, "-z"))
@@ -3864,12 +3906,8 @@ static void diff_flush_raw(struct diff_filepair *p, struct diff_options *opt)
 {
        int line_termination = opt->line_termination;
        int inter_name_termination = line_termination ? '\t' : '\0';
-       if (opt->output_prefix) {
-               struct strbuf *msg = NULL;
-               msg = opt->output_prefix(opt, opt->output_prefix_data);
-               fprintf(opt->file, "%s", msg->buf);
-       }
 
+       fprintf(opt->file, "%s", diff_line_prefix(opt));
        if (!(opt->output_format & DIFF_FORMAT_NAME_STATUS)) {
                fprintf(opt->file, ":%06o %06o %s ", p->one->mode, p->two->mode,
                        diff_unique_abbrev(p->one->sha1, opt->abbrev));
@@ -4139,12 +4177,7 @@ static void show_rename_copy(FILE *file, const char *renamecopy, struct diff_fil
 static void diff_summary(struct diff_options *opt, struct diff_filepair *p)
 {
        FILE *file = opt->file;
-       char *line_prefix = "";
-
-       if (opt->output_prefix) {
-               struct strbuf *buf = opt->output_prefix(opt, opt->output_prefix_data);
-               line_prefix = buf->buf;
-       }
+       const char *line_prefix = diff_line_prefix(opt);
 
        switch(p->status) {
        case DIFF_STATUS_DELETED:
@@ -4445,13 +4478,9 @@ 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);
+                       fprintf(options->file, "%s%c",
+                               diff_line_prefix(options),
+                               options->line_termination);
                        if (options->stat_sep) {
                                /* attach patch instead of inline */
                                fputs(options->stat_sep, options->file);
@@ -4655,7 +4684,7 @@ int diff_result_code(struct diff_options *opt, int status)
 {
        int result = 0;
 
-       diff_warn_rename_limit("diff.renamelimit",
+       diff_warn_rename_limit("diff.renameLimit",
                               opt->needed_rename_limit,
                               opt->degraded_cc_to_c);
        if (!DIFF_OPT_TST(opt, EXIT_WITH_STATUS) &&
@@ -4879,3 +4908,19 @@ 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();
+}