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-rw-r--r--Makefile3
-rw-r--r--describe.c118
2 files changed, 120 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 3395a9e10..47e78982e 100644
--- a/Makefile
+++ b/Makefile
@@ -135,7 +135,8 @@ PROGRAMS = \
git-unpack-objects$X git-update-index$X git-update-server-info$X \
git-upload-pack$X git-verify-pack$X git-write-tree$X \
git-update-ref$X git-symbolic-ref$X git-check-ref-format$X \
- git-name-rev$X git-pack-redundant$X git-repo-config$X git-var$X
+ git-name-rev$X git-pack-redundant$X git-repo-config$X git-var$X \
+ git-describe$X
# what 'all' will build and 'install' will install.
ALL_PROGRAMS = $(PROGRAMS) $(SIMPLE_PROGRAMS) $(SCRIPTS) git$X
diff --git a/describe.c b/describe.c
new file mode 100644
index 000000000..ebfa4290e
--- /dev/null
+++ b/describe.c
@@ -0,0 +1,118 @@
+#include "cache.h"
+#include "commit.h"
+#include "refs.h"
+
+#define SEEN (1u << 0)
+
+static const char describe_usage[] = "git-describe [--all] <committish>*";
+
+static int all = 0; /* Default to tags only */
+
+static int names = 0, allocs = 0;
+static struct commit_name {
+ const struct commit *commit;
+ char path[];
+} **name_array = NULL;
+
+static struct commit_name *match(struct commit *cmit)
+{
+ int i = names;
+ struct commit_name **p = name_array;
+
+ while (i-- > 0) {
+ struct commit_name *n = *p++;
+ if (n->commit == cmit)
+ return n;
+ }
+ return NULL;
+}
+
+static void add_to_known_names(const char *path, const struct commit *commit)
+{
+ int idx;
+ int len = strlen(path)+1;
+ struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
+
+ name->commit = commit;
+ memcpy(name->path, path, len);
+ idx = names;
+ if (idx >= allocs) {
+ allocs = (idx + 50) * 3 / 2;
+ name_array = xrealloc(name_array, allocs*sizeof(*name_array));
+ }
+ name_array[idx] = name;
+ names = ++idx;
+}
+
+static int get_name(const char *path, const unsigned char *sha1)
+{
+ struct commit *commit = lookup_commit_reference_gently(sha1, 1);
+ if (!commit)
+ return 0;
+ if (!all && strncmp(path, "refs/tags/", 10))
+ return 0;
+ add_to_known_names(path, commit);
+ return 0;
+}
+
+static int compare_names(const void *_a, const void *_b)
+{
+ struct commit_name *a = *(struct commit_name **)_a;
+ struct commit_name *b = *(struct commit_name **)_b;
+ unsigned long a_date = a->commit->date;
+ unsigned long b_date = b->commit->date;
+ return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
+}
+
+static void describe(struct commit *cmit)
+{
+ struct commit_list *list;
+ static int initialized = 0;
+ struct commit_name *n;
+
+ if (!initialized) {
+ initialized = 1;
+ for_each_ref(get_name);
+ qsort(name_array, names, sizeof(*name_array), compare_names);
+ }
+
+ n = match(cmit);
+ if (n) {
+ printf("%s\n", n->path);
+ return;
+ }
+
+ list = NULL;
+ commit_list_insert(cmit, &list);
+ while (list) {
+ struct commit *c = pop_most_recent_commit(&list, SEEN);
+ n = match(c);
+ if (n) {
+ printf("%s-g%.8s\n", n->path, sha1_to_hex(cmit->object.sha1));
+ return;
+ }
+ }
+}
+
+int main(int argc, char **argv)
+{
+ int i;
+
+ for (i = 1; i < argc; i++) {
+ const char *arg = argv[i];
+ unsigned char sha1[20];
+ struct commit *cmit;
+
+ if (!strcmp(arg, "--all")) {
+ all = 1;
+ continue;
+ }
+ if (get_sha1(arg, sha1) < 0)
+ usage(describe_usage);
+ cmit = lookup_commit_reference(sha1);
+ if (!cmit)
+ usage(describe_usage);
+ describe(cmit);
+ }
+ return 0;
+}