builtin-merge: avoid run_command_v_opt() for recursive and subtree
[gitweb.git] / builtin-blame.c
index fbc441fb9f219d85f9f6504ed1f2024a77e40593..e4d12de8a994434058745439a86929c0d556a3ec 100644 (file)
 #include "quote.h"
 #include "xdiff-interface.h"
 #include "cache-tree.h"
-#include "path-list.h"
+#include "string-list.h"
 #include "mailmap.h"
+#include "parse-options.h"
 
-static char blame_usage[] =
-"git-blame [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-p] [-w] [-L n,m] [-S <revs-file>] [-M] [-C] [-C] [--contents <filename>] [--incremental] [commit] [--] file\n"
-"  -c                  Use the same output mode as git-annotate (Default: off)\n"
-"  -b                  Show blank SHA-1 for boundary commits (Default: off)\n"
-"  -l                  Show long commit SHA1 (Default: off)\n"
-"  --root              Do not treat root commits as boundaries (Default: off)\n"
-"  -t                  Show raw timestamp (Default: off)\n"
-"  -f, --show-name     Show original filename (Default: auto)\n"
-"  -n, --show-number   Show original linenumber (Default: off)\n"
-"  -s                  Suppress author name and timestamp (Default: off)\n"
-"  -p, --porcelain     Show in a format designed for machine consumption\n"
-"  -w                  Ignore whitespace differences\n"
-"  -L n,m              Process only line range n,m, counting from 1\n"
-"  -M, -C              Find line movements within and across files\n"
-"  --incremental       Show blame entries as we find them, incrementally\n"
-"  --contents file     Use <file>'s contents as the final image\n"
-"  -S revs-file        Use revisions from revs-file instead of calling git-rev-list\n";
+static char blame_usage[] = "git blame [options] [rev-opts] [rev] [--] file";
+
+static const char *blame_opt_usage[] = {
+       blame_usage,
+       "",
+       "[rev-opts] are documented in git-rev-list(1)",
+       NULL
+};
 
 static int longest_file;
 static int longest_author;
@@ -43,11 +35,12 @@ static int max_orig_digits;
 static int max_digits;
 static int max_score_digits;
 static int show_root;
+static int reverse;
 static int blank_boundary;
 static int incremental;
 static int cmd_is_annotate;
 static int xdl_opts = XDF_NEED_MINIMAL;
-static struct path_list mailmap;
+static struct string_list mailmap;
 
 #ifndef DEBUG
 #define DEBUG 0
@@ -160,6 +153,10 @@ struct blame_entry {
         */
        char guilty;
 
+       /* true if the entry has been scanned for copies in the current parent
+        */
+       char scanned;
+
        /* the line number of the first line of this group in the
         * suspect's file; internally all line numbers are 0 based.
         */
@@ -177,7 +174,7 @@ struct blame_entry {
 struct scoreboard {
        /* the final commit (i.e. where we started digging from) */
        struct commit *final;
-
+       struct rev_info *revs;
        const char *path;
 
        /*
@@ -468,7 +465,6 @@ struct patch {
 };
 
 struct blame_diff_state {
-       struct xdiff_emit_state xm;
        struct patch *ret;
        unsigned hunk_post_context;
        unsigned hunk_in_pre_context : 1;
@@ -531,15 +527,12 @@ static struct patch *compare_buffer(mmfile_t *file_p, mmfile_t *file_o,
        xpp.flags = xdl_opts;
        memset(&xecfg, 0, sizeof(xecfg));
        xecfg.ctxlen = context;
-       ecb.outf = xdiff_outf;
-       ecb.priv = &state;
        memset(&state, 0, sizeof(state));
-       state.xm.consume = process_u_diff;
        state.ret = xmalloc(sizeof(struct patch));
        state.ret->chunks = NULL;
        state.ret->num = 0;
 
-       xdi_diff(file_p, file_o, &xpp, &xecfg, &ecb);
+       xdi_diff_outf(file_p, file_o, process_u_diff, &state, &xpp, &xecfg, &ecb);
 
        if (state.ret->num) {
                struct chunk *chunk;
@@ -1015,7 +1008,8 @@ static int find_move_in_parent(struct scoreboard *sb,
        while (made_progress) {
                made_progress = 0;
                for (e = sb->ent; e; e = e->next) {
-                       if (e->guilty || !same_suspect(e->suspect, target))
+                       if (e->guilty || !same_suspect(e->suspect, target) ||
+                           ent_score(sb, e) < blame_move_score)
                                continue;
                        find_copy_in_blob(sb, e, parent, split, &file_p);
                        if (split[1].suspect &&
@@ -1040,6 +1034,7 @@ struct blame_list {
  */
 static struct blame_list *setup_blame_list(struct scoreboard *sb,
                                           struct origin *target,
+                                          int min_score,
                                           int *num_ents_p)
 {
        struct blame_entry *e;
@@ -1047,18 +1042,32 @@ static struct blame_list *setup_blame_list(struct scoreboard *sb,
        struct blame_list *blame_list = NULL;
 
        for (e = sb->ent, num_ents = 0; e; e = e->next)
-               if (!e->guilty && same_suspect(e->suspect, target))
+               if (!e->scanned && !e->guilty &&
+                   same_suspect(e->suspect, target) &&
+                   min_score < ent_score(sb, e))
                        num_ents++;
        if (num_ents) {
                blame_list = xcalloc(num_ents, sizeof(struct blame_list));
                for (e = sb->ent, i = 0; e; e = e->next)
-                       if (!e->guilty && same_suspect(e->suspect, target))
+                       if (!e->scanned && !e->guilty &&
+                           same_suspect(e->suspect, target) &&
+                           min_score < ent_score(sb, e))
                                blame_list[i++].ent = e;
        }
        *num_ents_p = num_ents;
        return blame_list;
 }
 
+/*
+ * Reset the scanned status on all entries.
+ */
+static void reset_scanned_flag(struct scoreboard *sb)
+{
+       struct blame_entry *e;
+       for (e = sb->ent; e; e = e->next)
+               e->scanned = 0;
+}
+
 /*
  * For lines target is suspected for, see if we can find code movement
  * across file boundary from the parent commit.  porigin is the path
@@ -1077,7 +1086,7 @@ static int find_copy_in_parent(struct scoreboard *sb,
        struct blame_list *blame_list;
        int num_ents;
 
-       blame_list = setup_blame_list(sb, target, &num_ents);
+       blame_list = setup_blame_list(sb, target, blame_copy_score, &num_ents);
        if (!blame_list)
                return 1; /* nothing remains for this target */
 
@@ -1151,18 +1160,21 @@ static int find_copy_in_parent(struct scoreboard *sb,
                                split_blame(sb, split, blame_list[j].ent);
                                made_progress = 1;
                        }
+                       else
+                               blame_list[j].ent->scanned = 1;
                        decref_split(split);
                }
                free(blame_list);
 
                if (!made_progress)
                        break;
-               blame_list = setup_blame_list(sb, target, &num_ents);
+               blame_list = setup_blame_list(sb, target, blame_copy_score, &num_ents);
                if (!blame_list) {
                        retval = 1;
                        break;
                }
        }
+       reset_scanned_flag(sb);
        diff_flush(&diff_opts);
        diff_tree_release_paths(&diff_opts);
        return retval;
@@ -1196,15 +1208,17 @@ static void pass_whole_blame(struct scoreboard *sb,
  * "parent" (and "porigin"), but what we mean is to find scapegoat to
  * exonerate ourselves.
  */
-static struct commit_list *first_scapegoat(struct commit *commit)
+static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit *commit)
 {
-       return commit->parents;
+       if (!reverse)
+               return commit->parents;
+       return lookup_decoration(&revs->children, &commit->object);
 }
 
-static int num_scapegoats(struct commit *commit)
+static int num_scapegoats(struct rev_info *revs, struct commit *commit)
 {
        int cnt;
-       struct commit_list *l = first_scapegoat(commit);
+       struct commit_list *l = first_scapegoat(revs, commit);
        for (cnt = 0; l; l = l->next)
                cnt++;
        return cnt;
@@ -1214,13 +1228,14 @@ static int num_scapegoats(struct commit *commit)
 
 static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
 {
+       struct rev_info *revs = sb->revs;
        int i, pass, num_sg;
        struct commit *commit = origin->commit;
        struct commit_list *sg;
        struct origin *sg_buf[MAXSG];
        struct origin *porigin, **sg_origin = sg_buf;
 
-       num_sg = num_scapegoats(commit);
+       num_sg = num_scapegoats(revs, commit);
        if (!num_sg)
                goto finish;
        else if (num_sg < ARRAY_SIZE(sg_buf))
@@ -1237,7 +1252,7 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
                                       struct commit *, struct origin *);
                find = pass ? find_rename : find_origin;
 
-               for (i = 0, sg = first_scapegoat(commit);
+               for (i = 0, sg = first_scapegoat(revs, commit);
                     i < num_sg && sg;
                     sg = sg->next, i++) {
                        struct commit *p = sg->item;
@@ -1270,7 +1285,7 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
        }
 
        num_commits++;
-       for (i = 0, sg = first_scapegoat(commit);
+       for (i = 0, sg = first_scapegoat(revs, commit);
             i < num_sg && sg;
             sg = sg->next, i++) {
                struct origin *porigin = sg_origin[i];
@@ -1284,7 +1299,7 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
         * Optionally find moves in parents' files.
         */
        if (opt & PICKAXE_BLAME_MOVE)
-               for (i = 0, sg = first_scapegoat(commit);
+               for (i = 0, sg = first_scapegoat(revs, commit);
                     i < num_sg && sg;
                     sg = sg->next, i++) {
                        struct origin *porigin = sg_origin[i];
@@ -1298,7 +1313,7 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
         * Optionally find copies from parents' files.
         */
        if (opt & PICKAXE_BLAME_COPY)
-               for (i = 0, sg = first_scapegoat(commit);
+               for (i = 0, sg = first_scapegoat(revs, commit);
                     i < num_sg && sg;
                     sg = sg->next, i++) {
                        struct origin *porigin = sg_origin[i];
@@ -1515,8 +1530,10 @@ static void found_guilty_entry(struct blame_entry *ent)
  * is still unknown, pick one blame_entry, and allow its current
  * suspect to pass blames to its parents.
  */
-static void assign_blame(struct scoreboard *sb, struct rev_info *revs, int opt)
+static void assign_blame(struct scoreboard *sb, int opt)
 {
+       struct rev_info *revs = sb->revs;
+
        while (1) {
                struct blame_entry *ent;
                struct commit *commit;
@@ -1537,8 +1554,9 @@ static void assign_blame(struct scoreboard *sb, struct rev_info *revs, int opt)
                commit = suspect->commit;
                if (!commit->object.parsed)
                        parse_commit(commit);
-               if (!(commit->object.flags & UNINTERESTING) &&
-                   !(revs->max_age != -1 && commit->date < revs->max_age))
+               if (reverse ||
+                   (!(commit->object.flags & UNINTERESTING) &&
+                    !(revs->max_age != -1 && commit->date < revs->max_age)))
                        pass_blame(sb, suspect, opt);
                else {
                        commit->object.flags |= UNINTERESTING;
@@ -1904,7 +1922,7 @@ static void sanity_check_refcnt(struct scoreboard *sb)
  * Used for the command line parsing; check if the path exists
  * in the working tree.
  */
-static int has_path_in_work_tree(const char *path)
+static int has_string_in_work_tree(const char *path)
 {
        struct stat st;
        return !lstat(path, &st);
@@ -2021,7 +2039,7 @@ static void prepare_blame_range(struct scoreboard *sb,
                usage(blame_usage);
 }
 
-static int git_blame_config(const char *var, const char *value)
+static int git_blame_config(const char *var, const char *value, void *cb)
 {
        if (!strcmp(var, "blame.showroot")) {
                show_root = git_config_bool(var, value);
@@ -2031,7 +2049,7 @@ static int git_blame_config(const char *var, const char *value)
                blank_boundary = git_config_bool(var, value);
                return 0;
        }
-       return git_default_config(var, value);
+       return git_default_config(var, value, cb);
 }
 
 /*
@@ -2154,10 +2172,11 @@ static struct commit *fake_working_tree_commit(const char *path, const char *con
        return commit;
 }
 
-static const char *prepare_final(struct scoreboard *sb, struct rev_info *revs)
+static const char *prepare_final(struct scoreboard *sb)
 {
        int i;
        const char *final_commit_name = NULL;
+       struct rev_info *revs = sb->revs;
 
        /*
         * There must be one and only one positive commit in the
@@ -2181,6 +2200,80 @@ static const char *prepare_final(struct scoreboard *sb, struct rev_info *revs)
        return final_commit_name;
 }
 
+static const char *prepare_initial(struct scoreboard *sb)
+{
+       int i;
+       const char *final_commit_name = NULL;
+       struct rev_info *revs = sb->revs;
+
+       /*
+        * There must be one and only one negative commit, and it must be
+        * the boundary.
+        */
+       for (i = 0; i < revs->pending.nr; i++) {
+               struct object *obj = revs->pending.objects[i].item;
+               if (!(obj->flags & UNINTERESTING))
+                       continue;
+               while (obj->type == OBJ_TAG)
+                       obj = deref_tag(obj, NULL, 0);
+               if (obj->type != OBJ_COMMIT)
+                       die("Non commit %s?", revs->pending.objects[i].name);
+               if (sb->final)
+                       die("More than one commit to dig down to %s and %s?",
+                           revs->pending.objects[i].name,
+                           final_commit_name);
+               sb->final = (struct commit *) obj;
+               final_commit_name = revs->pending.objects[i].name;
+       }
+       if (!final_commit_name)
+               die("No commit to dig down to?");
+       return final_commit_name;
+}
+
+static int blame_copy_callback(const struct option *option, const char *arg, int unset)
+{
+       int *opt = option->value;
+
+       /*
+        * -C enables copy from removed files;
+        * -C -C enables copy from existing files, but only
+        *       when blaming a new file;
+        * -C -C -C enables copy from existing files for
+        *          everybody
+        */
+       if (*opt & PICKAXE_BLAME_COPY_HARDER)
+               *opt |= PICKAXE_BLAME_COPY_HARDEST;
+       if (*opt & PICKAXE_BLAME_COPY)
+               *opt |= PICKAXE_BLAME_COPY_HARDER;
+       *opt |= PICKAXE_BLAME_COPY | PICKAXE_BLAME_MOVE;
+
+       if (arg)
+               blame_copy_score = parse_score(arg);
+       return 0;
+}
+
+static int blame_move_callback(const struct option *option, const char *arg, int unset)
+{
+       int *opt = option->value;
+
+       *opt |= PICKAXE_BLAME_MOVE;
+
+       if (arg)
+               blame_move_score = parse_score(arg);
+       return 0;
+}
+
+static int blame_bottomtop_callback(const struct option *option, const char *arg, int unset)
+{
+       const char **bottomtop = option->value;
+       if (!arg)
+               return -1;
+       if (*bottomtop)
+               die("More than one '-L n,m' option given");
+       *bottomtop = arg;
+       return 0;
+}
+
 int cmd_blame(int argc, const char **argv, const char *prefix)
 {
        struct rev_info revs;
@@ -2188,102 +2281,70 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        struct scoreboard sb;
        struct origin *o;
        struct blame_entry *ent;
-       int i, seen_dashdash, unk, opt;
-       long bottom, top, lno;
-       int output_option = 0;
-       int show_stats = 0;
-       const char *revs_file = NULL;
+       long dashdash_pos, bottom, top, lno;
        const char *final_commit_name = NULL;
        enum object_type type;
-       const char *bottomtop = NULL;
-       const char *contents_from = NULL;
+
+       static const char *bottomtop = NULL;
+       static int output_option = 0, opt = 0;
+       static int show_stats = 0;
+       static const char *revs_file = NULL;
+       static const char *contents_from = NULL;
+       static const struct option options[] = {
+               OPT_BOOLEAN(0, "incremental", &incremental, "Show blame entries as we find them, incrementally"),
+               OPT_BOOLEAN('b', NULL, &blank_boundary, "Show blank SHA-1 for boundary commits (Default: off)"),
+               OPT_BOOLEAN(0, "root", &show_root, "Do not treat root commits as boundaries (Default: off)"),
+               OPT_BOOLEAN(0, "show-stats", &show_stats, "Show work cost statistics"),
+               OPT_BIT(0, "score-debug", &output_option, "Show output score for blame entries", OUTPUT_SHOW_SCORE),
+               OPT_BIT('f', "show-name", &output_option, "Show original filename (Default: auto)", OUTPUT_SHOW_NAME),
+               OPT_BIT('n', "show-number", &output_option, "Show original linenumber (Default: off)", OUTPUT_SHOW_NUMBER),
+               OPT_BIT('p', "porcelain", &output_option, "Show in a format designed for machine consumption", OUTPUT_PORCELAIN),
+               OPT_BIT('c', NULL, &output_option, "Use the same output mode as git-annotate (Default: off)", OUTPUT_ANNOTATE_COMPAT),
+               OPT_BIT('t', NULL, &output_option, "Show raw timestamp (Default: off)", OUTPUT_RAW_TIMESTAMP),
+               OPT_BIT('l', NULL, &output_option, "Show long commit SHA1 (Default: off)", OUTPUT_LONG_OBJECT_NAME),
+               OPT_BIT('s', NULL, &output_option, "Suppress author name and timestamp (Default: off)", OUTPUT_NO_AUTHOR),
+               OPT_BIT('w', NULL, &xdl_opts, "Ignore whitespace differences", XDF_IGNORE_WHITESPACE),
+               OPT_STRING('S', NULL, &revs_file, "file", "Use revisions from <file> instead of calling git-rev-list"),
+               OPT_STRING(0, "contents", &contents_from, "file", "Use <file>'s contents as the final image"),
+               { OPTION_CALLBACK, 'C', NULL, &opt, "score", "Find line copies within and across files", PARSE_OPT_OPTARG, blame_copy_callback },
+               { OPTION_CALLBACK, 'M', NULL, &opt, "score", "Find line movements within and across files", PARSE_OPT_OPTARG, blame_move_callback },
+               OPT_CALLBACK('L', NULL, &bottomtop, "n,m", "Process only line range n,m, counting from 1", blame_bottomtop_callback),
+               OPT_END()
+       };
+
+       struct parse_opt_ctx_t ctx;
 
        cmd_is_annotate = !strcmp(argv[0], "annotate");
 
-       git_config(git_blame_config);
+       git_config(git_blame_config, NULL);
+       init_revisions(&revs, NULL);
        save_commit_buffer = 0;
-
-       opt = 0;
-       seen_dashdash = 0;
-       for (unk = i = 1; i < argc; i++) {
-               const char *arg = argv[i];
-               if (*arg != '-')
-                       break;
-               else if (!strcmp("-b", arg))
-                       blank_boundary = 1;
-               else if (!strcmp("--root", arg))
-                       show_root = 1;
-               else if (!strcmp(arg, "--show-stats"))
-                       show_stats = 1;
-               else if (!strcmp("-c", arg))
-                       output_option |= OUTPUT_ANNOTATE_COMPAT;
-               else if (!strcmp("-t", arg))
-                       output_option |= OUTPUT_RAW_TIMESTAMP;
-               else if (!strcmp("-l", arg))
-                       output_option |= OUTPUT_LONG_OBJECT_NAME;
-               else if (!strcmp("-s", arg))
-                       output_option |= OUTPUT_NO_AUTHOR;
-               else if (!strcmp("-w", arg))
-                       xdl_opts |= XDF_IGNORE_WHITESPACE;
-               else if (!strcmp("-S", arg) && ++i < argc)
-                       revs_file = argv[i];
-               else if (!prefixcmp(arg, "-M")) {
-                       opt |= PICKAXE_BLAME_MOVE;
-                       blame_move_score = parse_score(arg+2);
-               }
-               else if (!prefixcmp(arg, "-C")) {
-                       /*
-                        * -C enables copy from removed files;
-                        * -C -C enables copy from existing files, but only
-                        *       when blaming a new file;
-                        * -C -C -C enables copy from existing files for
-                        *          everybody
-                        */
-                       if (opt & PICKAXE_BLAME_COPY_HARDER)
-                               opt |= PICKAXE_BLAME_COPY_HARDEST;
-                       if (opt & PICKAXE_BLAME_COPY)
-                               opt |= PICKAXE_BLAME_COPY_HARDER;
-                       opt |= PICKAXE_BLAME_COPY | PICKAXE_BLAME_MOVE;
-                       blame_copy_score = parse_score(arg+2);
+       dashdash_pos = 0;
+
+       parse_options_start(&ctx, argc, argv, PARSE_OPT_KEEP_DASHDASH |
+                           PARSE_OPT_KEEP_ARGV0);
+       for (;;) {
+               switch (parse_options_step(&ctx, options, blame_opt_usage)) {
+               case PARSE_OPT_HELP:
+                       exit(129);
+               case PARSE_OPT_DONE:
+                       if (ctx.argv[0])
+                               dashdash_pos = ctx.cpidx;
+                       goto parse_done;
                }
-               else if (!prefixcmp(arg, "-L")) {
-                       if (!arg[2]) {
-                               if (++i >= argc)
-                                       usage(blame_usage);
-                               arg = argv[i];
-                       }
-                       else
-                               arg += 2;
-                       if (bottomtop)
-                               die("More than one '-L n,m' option given");
-                       bottomtop = arg;
-               }
-               else if (!strcmp("--contents", arg)) {
-                       if (++i >= argc)
-                               usage(blame_usage);
-                       contents_from = argv[i];
-               }
-               else if (!strcmp("--incremental", arg))
-                       incremental = 1;
-               else if (!strcmp("--score-debug", arg))
-                       output_option |= OUTPUT_SHOW_SCORE;
-               else if (!strcmp("-f", arg) ||
-                        !strcmp("--show-name", arg))
-                       output_option |= OUTPUT_SHOW_NAME;
-               else if (!strcmp("-n", arg) ||
-                        !strcmp("--show-number", arg))
-                       output_option |= OUTPUT_SHOW_NUMBER;
-               else if (!strcmp("-p", arg) ||
-                        !strcmp("--porcelain", arg))
-                       output_option |= OUTPUT_PORCELAIN;
-               else if (!strcmp("--", arg)) {
-                       seen_dashdash = 1;
-                       i++;
-                       break;
+
+               if (!strcmp(ctx.argv[0], "--reverse")) {
+                       ctx.argv[0] = "--children";
+                       reverse = 1;
                }
-               else
-                       argv[unk++] = arg;
+               parse_revision_opt(&revs, &ctx, options, blame_opt_usage);
        }
+parse_done:
+       argc = parse_options_end(&ctx);
+
+       if (DIFF_OPT_TST(&revs.diffopt, FIND_COPIES_HARDER))
+               opt |= (PICKAXE_BLAME_COPY | PICKAXE_BLAME_MOVE |
+                       PICKAXE_BLAME_COPY_HARDER);
 
        if (!blame_move_score)
                blame_move_score = BLAME_DEFAULT_MOVE_SCORE;
@@ -2297,96 +2358,60 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
         *
         * The remaining are:
         *
-        * (1) if seen_dashdash, its either
-        *     "-options -- <path>" or
-        *     "-options -- <path> <rev>".
-        *     but the latter is allowed only if there is no
-        *     options that we passed to revision machinery.
+        * (1) if dashdash_pos != 0, its either
+        *     "blame [revisions] -- <path>" or
+        *     "blame -- <path> <rev>"
         *
-        * (2) otherwise, we may have "--" somewhere later and
-        *     might be looking at the first one of multiple 'rev'
-        *     parameters (e.g. " master ^next ^maint -- path").
-        *     See if there is a dashdash first, and give the
-        *     arguments before that to revision machinery.
-        *     After that there must be one 'path'.
+        * (2) otherwise, its one of the two:
+        *     "blame [revisions] <path>"
+        *     "blame <path> <rev>"
         *
-        * (3) otherwise, its one of the three:
-        *     "-options <path> <rev>"
-        *     "-options <rev> <path>"
-        *     "-options <path>"
-        *     but again the first one is allowed only if
-        *     there is no options that we passed to revision
-        *     machinery.
+        * Note that we must strip out <path> from the arguments: we do not
+        * want the path pruning but we may want "bottom" processing.
         */
-
-       if (seen_dashdash) {
-               /* (1) */
-               if (argc <= i)
-                       usage(blame_usage);
-               path = add_prefix(prefix, argv[i]);
-               if (i + 1 == argc - 1) {
-                       if (unk != 1)
-                               usage(blame_usage);
-                       argv[unk++] = argv[i + 1];
+       if (dashdash_pos) {
+               switch (argc - dashdash_pos - 1) {
+               case 2: /* (1b) */
+                       if (argc != 4)
+                               usage_with_options(blame_opt_usage, options);
+                       /* reorder for the new way: <rev> -- <path> */
+                       argv[1] = argv[3];
+                       argv[3] = argv[2];
+                       argv[2] = "--";
+                       /* FALLTHROUGH */
+               case 1: /* (1a) */
+                       path = add_prefix(prefix, argv[--argc]);
+                       argv[argc] = NULL;
+                       break;
+               default:
+                       usage_with_options(blame_opt_usage, options);
                }
-               else if (i + 1 != argc)
-                       /* garbage at end */
-                       usage(blame_usage);
-       }
-       else {
-               int j;
-               for (j = i; !seen_dashdash && j < argc; j++)
-                       if (!strcmp(argv[j], "--"))
-                               seen_dashdash = j;
-               if (seen_dashdash) {
-                       /* (2) */
-                       if (seen_dashdash + 1 != argc - 1)
-                               usage(blame_usage);
-                       path = add_prefix(prefix, argv[seen_dashdash + 1]);
-                       for (j = i; j < seen_dashdash; j++)
-                               argv[unk++] = argv[j];
+       } else {
+               if (argc < 2)
+                       usage_with_options(blame_opt_usage, options);
+               path = add_prefix(prefix, argv[argc - 1]);
+               if (argc == 3 && !has_string_in_work_tree(path)) { /* (2b) */
+                       path = add_prefix(prefix, argv[1]);
+                       argv[1] = argv[2];
                }
-               else {
-                       /* (3) */
-                       if (argc <= i)
-                               usage(blame_usage);
-                       path = add_prefix(prefix, argv[i]);
-                       if (i + 1 == argc - 1) {
-                               final_commit_name = argv[i + 1];
-
-                               /* if (unk == 1) we could be getting
-                                * old-style
-                                */
-                               if (unk == 1 && !has_path_in_work_tree(path)) {
-                                       path = add_prefix(prefix, argv[i + 1]);
-                                       final_commit_name = argv[i];
-                               }
-                       }
-                       else if (i != argc - 1)
-                               usage(blame_usage); /* garbage at end */
+               argv[argc - 1] = "--";
 
-                       setup_work_tree();
-                       if (!has_path_in_work_tree(path))
-                               die("cannot stat path %s: %s",
-                                   path, strerror(errno));
-               }
+               setup_work_tree();
+               if (!has_string_in_work_tree(path))
+                       die("cannot stat path %s: %s", path, strerror(errno));
        }
 
-       if (final_commit_name)
-               argv[unk++] = final_commit_name;
-
-       /*
-        * Now we got rev and path.  We do not want the path pruning
-        * but we may want "bottom" processing.
-        */
-       argv[unk++] = "--"; /* terminate the rev name */
-       argv[unk] = NULL;
-
-       init_revisions(&revs, NULL);
-       setup_revisions(unk, argv, &revs, NULL);
+       setup_revisions(argc, argv, &revs, NULL);
        memset(&sb, 0, sizeof(sb));
 
-       final_commit_name = prepare_final(&sb, &revs);
+       sb.revs = &revs;
+       if (!reverse)
+               final_commit_name = prepare_final(&sb);
+       else if (contents_from)
+               die("--contents and --children do not blend well.");
+       else
+               final_commit_name = prepare_initial(&sb);
+
        if (!sb.final) {
                /*
                 * "--not A B -- path" without anything positive;
@@ -2464,7 +2489,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
        if (!incremental)
                setup_pager();
 
-       assign_blame(&sb, &revs, opt);
+       assign_blame(&sb, opt);
 
        if (incremental)
                return 0;