1 files changed, 437 insertions, 0 deletions

diff --git a/builtin/describe.c b/builtin/describe.c
new file mode 100644
index 0000000000..43caff2ffe
--- /dev/null
+++ b/builtin/describe.c
@@ -0,0 +1,437 @@
+#include "cache.h"
+#include "commit.h"
+#include "tag.h"
+#include "refs.h"
+#include "builtin.h"
+#include "exec_cmd.h"
+#include "parse-options.h"
+#include "diff.h"
+
+#define SEEN		(1u<<0)
+#define MAX_TAGS	(FLAG_BITS - 1)
+
+static const char * const describe_usage[] = {
+	"git describe [options] <committish>*",
+	"git describe [options] --dirty",
+	NULL
+};
+
+static int debug;	/* Display lots of verbose info */
+static int all;	/* Any valid ref can be used */
+static int tags;	/* Allow lightweight tags */
+static int longformat;
+static int abbrev = DEFAULT_ABBREV;
+static int max_candidates = 10;
+static int found_names;
+static const char *pattern;
+static int always;
+static const char *dirty;
+
+/* diff-index command arguments to check if working tree is dirty. */
+static const char *diff_index_args[] = {
+	"diff-index", "--quiet", "HEAD", "--", NULL
+};
+
+
+struct commit_name {
+	struct tag *tag;
+	unsigned prio:2; /* annotated tag = 2, tag = 1, head = 0 */
+	unsigned name_checked:1;
+	unsigned char sha1[20];
+	char path[FLEX_ARRAY]; /* more */
+};
+static const char *prio_names[] = {
+	"head", "lightweight", "annotated",
+};
+
+static int replace_name(struct commit_name *e,
+			       int prio,
+			       const unsigned char *sha1,
+			       struct tag **tag)
+{
+	if (!e || e->prio < prio)
+		return 1;
+
+	if (e->prio == 2 && prio == 2) {
+		/* Multiple annotated tags point to the same commit.
+		 * Select one to keep based upon their tagger date.
+		 */
+		struct tag *t;
+
+		if (!e->tag) {
+			t = lookup_tag(e->sha1);
+			if (!t || parse_tag(t))
+				return 1;
+			e->tag = t;
+		}
+
+		t = lookup_tag(sha1);
+		if (!t || parse_tag(t))
+			return 0;
+		*tag = t;
+
+		if (e->tag->date < t->date)
+			return 1;
+	}
+
+	return 0;
+}
+
+static void add_to_known_names(const char *path,
+			       struct commit *commit,
+			       int prio,
+			       const unsigned char *sha1)
+{
+	struct commit_name *e = commit->util;
+	struct tag *tag = NULL;
+	if (replace_name(e, prio, sha1, &tag)) {
+		size_t len = strlen(path)+1;
+		free(e);
+		e = xmalloc(sizeof(struct commit_name) + len);
+		e->tag = tag;
+		e->prio = prio;
+		e->name_checked = 0;
+		hashcpy(e->sha1, sha1);
+		memcpy(e->path, path, len);
+		commit->util = e;
+	}
+	found_names = 1;
+}
+
+static int get_name(const char *path, const unsigned char *sha1, int flag, void *cb_data)
+{
+	int might_be_tag = !prefixcmp(path, "refs/tags/");
+	struct commit *commit;
+	struct object *object;
+	unsigned char peeled[20];
+	int is_tag, prio;
+
+	if (!all && !might_be_tag)
+		return 0;
+
+	if (!peel_ref(path, peeled) && !is_null_sha1(peeled)) {
+		commit = lookup_commit_reference_gently(peeled, 1);
+		if (!commit)
+			return 0;
+		is_tag = !!hashcmp(sha1, commit->object.sha1);
+	} else {
+		commit = lookup_commit_reference_gently(sha1, 1);
+		object = parse_object(sha1);
+		if (!commit || !object)
+			return 0;
+		is_tag = object->type == OBJ_TAG;
+	}
+
+	/* If --all, then any refs are used.
+	 * If --tags, then any tags are used.
+	 * Otherwise only annotated tags are used.
+	 */
+	if (might_be_tag) {
+		if (is_tag)
+			prio = 2;
+		else
+			prio = 1;
+
+		if (pattern && fnmatch(pattern, path + 10, 0))
+			prio = 0;
+	}
+	else
+		prio = 0;
+
+	if (!all) {
+		if (!prio)
+			return 0;
+	}
+	add_to_known_names(all ? path + 5 : path + 10, commit, prio, sha1);
+	return 0;
+}
+
+struct possible_tag {
+	struct commit_name *name;
+	int depth;
+	int found_order;
+	unsigned flag_within;
+};
+
+static int compare_pt(const void *a_, const void *b_)
+{
+	struct possible_tag *a = (struct possible_tag *)a_;
+	struct possible_tag *b = (struct possible_tag *)b_;
+	if (a->depth != b->depth)
+		return a->depth - b->depth;
+	if (a->found_order != b->found_order)
+		return a->found_order - b->found_order;
+	return 0;
+}
+
+static unsigned long finish_depth_computation(
+	struct commit_list **list,
+	struct possible_tag *best)
+{
+	unsigned long seen_commits = 0;
+	while (*list) {
+		struct commit *c = pop_commit(list);
+		struct commit_list *parents = c->parents;
+		seen_commits++;
+		if (c->object.flags & best->flag_within) {
+			struct commit_list *a = *list;
+			while (a) {
+				struct commit *i = a->item;
+				if (!(i->object.flags & best->flag_within))
+					break;
+				a = a->next;
+			}
+			if (!a)
+				break;
+		} else
+			best->depth++;
+		while (parents) {
+			struct commit *p = parents->item;
+			parse_commit(p);
+			if (!(p->object.flags & SEEN))
+				insert_by_date(p, list);
+			p->object.flags |= c->object.flags;
+			parents = parents->next;
+		}
+	}
+	return seen_commits;
+}
+
+static void display_name(struct commit_name *n)
+{
+	if (n->prio == 2 && !n->tag) {
+		n->tag = lookup_tag(n->sha1);
+		if (!n->tag || parse_tag(n->tag))
+			die("annotated tag %s not available", n->path);
+	}
+	if (n->tag && !n->name_checked) {
+		if (!n->tag->tag)
+			die("annotated tag %s has no embedded name", n->path);
+		if (strcmp(n->tag->tag, all ? n->path + 5 : n->path))
+			warning("tag '%s' is really '%s' here", n->tag->tag, n->path);
+		n->name_checked = 1;
+	}
+
+	if (n->tag)
+		printf("%s", n->tag->tag);
+	else
+		printf("%s", n->path);
+}
+
+static void show_suffix(int depth, const unsigned char *sha1)
+{
+	printf("-%d-g%s", depth, find_unique_abbrev(sha1, abbrev));
+}
+
+static void describe(const char *arg, int last_one)
+{
+	unsigned char sha1[20];
+	struct commit *cmit, *gave_up_on = NULL;
+	struct commit_list *list;
+	struct commit_name *n;
+	struct possible_tag all_matches[MAX_TAGS];
+	unsigned int match_cnt = 0, annotated_cnt = 0, cur_match;
+	unsigned long seen_commits = 0;
+	unsigned int unannotated_cnt = 0;
+
+	if (get_sha1(arg, sha1))
+		die("Not a valid object name %s", arg);
+	cmit = lookup_commit_reference(sha1);
+	if (!cmit)
+		die("%s is not a valid '%s' object", arg, commit_type);
+
+	n = cmit->util;
+	if (n && (tags || all || n->prio == 2)) {
+		/*
+		 * Exact match to an existing ref.
+		 */
+		display_name(n);
+		if (longformat)
+			show_suffix(0, n->tag ? n->tag->tagged->sha1 : sha1);
+		if (dirty)
+			printf("%s", dirty);
+		printf("\n");
+		return;
+	}
+
+	if (!max_candidates)
+		die("no tag exactly matches '%s'", sha1_to_hex(cmit->object.sha1));
+	if (debug)
+		fprintf(stderr, "searching to describe %s\n", arg);
+
+	list = NULL;
+	cmit->object.flags = SEEN;
+	commit_list_insert(cmit, &list);
+	while (list) {
+		struct commit *c = pop_commit(&list);
+		struct commit_list *parents = c->parents;
+		seen_commits++;
+		n = c->util;
+		if (n) {
+			if (!tags && !all && n->prio < 2) {
+				unannotated_cnt++;
+			} else if (match_cnt < max_candidates) {
+				struct possible_tag *t = &all_matches[match_cnt++];
+				t->name = n;
+				t->depth = seen_commits - 1;
+				t->flag_within = 1u << match_cnt;
+				t->found_order = match_cnt;
+				c->object.flags |= t->flag_within;
+				if (n->prio == 2)
+					annotated_cnt++;
+			}
+			else {
+				gave_up_on = c;
+				break;
+			}
+		}
+		for (cur_match = 0; cur_match < match_cnt; cur_match++) {
+			struct possible_tag *t = &all_matches[cur_match];
+			if (!(c->object.flags & t->flag_within))
+				t->depth++;
+		}
+		if (annotated_cnt && !list) {
+			if (debug)
+				fprintf(stderr, "finished search at %s\n",
+					sha1_to_hex(c->object.sha1));
+			break;
+		}
+		while (parents) {
+			struct commit *p = parents->item;
+			parse_commit(p);
+			if (!(p->object.flags & SEEN))
+				insert_by_date(p, &list);
+			p->object.flags |= c->object.flags;
+			parents = parents->next;
+		}
+	}
+
+	if (!match_cnt) {
+		const unsigned char *sha1 = cmit->object.sha1;
+		if (always) {
+			printf("%s", find_unique_abbrev(sha1, abbrev));
+			if (dirty)
+				printf("%s", dirty);
+			printf("\n");
+			return;
+		}
+		if (unannotated_cnt)
+			die("No annotated tags can describe '%s'.\n"
+			    "However, there were unannotated tags: try --tags.",
+			    sha1_to_hex(sha1));
+		else
+			die("No tags can describe '%s'.\n"
+			    "Try --always, or create some tags.",
+			    sha1_to_hex(sha1));
+	}
+
+	qsort(all_matches, match_cnt, sizeof(all_matches[0]), compare_pt);
+
+	if (gave_up_on) {
+		insert_by_date(gave_up_on, &list);
+		seen_commits--;
+	}
+	seen_commits += finish_depth_computation(&list, &all_matches[0]);
+	free_commit_list(list);
+
+	if (debug) {
+		for (cur_match = 0; cur_match < match_cnt; cur_match++) {
+			struct possible_tag *t = &all_matches[cur_match];
+			fprintf(stderr, " %-11s %8d %s\n",
+				prio_names[t->name->prio],
+				t->depth, t->name->path);
+		}
+		fprintf(stderr, "traversed %lu commits\n", seen_commits);
+		if (gave_up_on) {
+			fprintf(stderr,
+				"more than %i tags found; listed %i most recent\n"
+				"gave up search at %s\n",
+				max_candidates, max_candidates,
+				sha1_to_hex(gave_up_on->object.sha1));
+		}
+	}
+
+	display_name(all_matches[0].name);
+	if (abbrev)
+		show_suffix(all_matches[0].depth, cmit->object.sha1);
+	if (dirty)
+		printf("%s", dirty);
+	printf("\n");
+
+	if (!last_one)
+		clear_commit_marks(cmit, -1);
+}
+
+int cmd_describe(int argc, const char **argv, const char *prefix)
+{
+	int contains = 0;
+	struct option options[] = {
+		OPT_BOOLEAN(0, "contains",   &contains, "find the tag that comes after the commit"),
+		OPT_BOOLEAN(0, "debug",      &debug, "debug search strategy on stderr"),
+		OPT_BOOLEAN(0, "all",        &all, "use any ref in .git/refs"),
+		OPT_BOOLEAN(0, "tags",       &tags, "use any tag in .git/refs/tags"),
+		OPT_BOOLEAN(0, "long",       &longformat, "always use long format"),
+		OPT__ABBREV(&abbrev),
+		OPT_SET_INT(0, "exact-match", &max_candidates,
+			    "only output exact matches", 0),
+		OPT_INTEGER(0, "candidates", &max_candidates,
+			    "consider <n> most recent tags (default: 10)"),
+		OPT_STRING(0, "match",       &pattern, "pattern",
+			   "only consider tags matching <pattern>"),
+		OPT_BOOLEAN(0, "always",     &always,
+			   "show abbreviated commit object as fallback"),
+		{OPTION_STRING, 0, "dirty",  &dirty, "mark",
+			   "append <mark> on dirty working tree (default: \"-dirty\")",
+		 PARSE_OPT_OPTARG, NULL, (intptr_t) "-dirty"},
+		OPT_END(),
+	};
+
+	argc = parse_options(argc, argv, prefix, options, describe_usage, 0);
+	if (max_candidates < 0)
+		max_candidates = 0;
+	else if (max_candidates > MAX_TAGS)
+		max_candidates = MAX_TAGS;
+
+	save_commit_buffer = 0;
+
+	if (longformat && abbrev == 0)
+		die("--long is incompatible with --abbrev=0");
+
+	if (contains) {
+		const char **args = xmalloc((7 + argc) * sizeof(char *));
+		int i = 0;
+		args[i++] = "name-rev";
+		args[i++] = "--name-only";
+		args[i++] = "--no-undefined";
+		if (always)
+			args[i++] = "--always";
+		if (!all) {
+			args[i++] = "--tags";
+			if (pattern) {
+				char *s = xmalloc(strlen("--refs=refs/tags/") + strlen(pattern) + 1);
+				sprintf(s, "--refs=refs/tags/%s", pattern);
+				args[i++] = s;
+			}
+		}
+		memcpy(args + i, argv, argc * sizeof(char *));
+		args[i + argc] = NULL;
+		return cmd_name_rev(i + argc, args, prefix);
+	}
+
+	for_each_ref(get_name, NULL);
+	if (!found_names && !always)
+		die("No names found, cannot describe anything.");
+
+	if (argc == 0) {
+		if (dirty && !cmd_diff_index(ARRAY_SIZE(diff_index_args) - 1, diff_index_args, prefix))
+			dirty = NULL;
+		describe("HEAD", 1);
+	} else if (dirty) {
+		die("--dirty is incompatible with committishes");
+	} else {
+		while (argc-- > 0) {
+			describe(*argv++, argc == 0);
+		}
+	}
+	return 0;
+}