Add a "git-describe" command
[git/git.git] / describe.c
CommitLineData
908e5310
LT
1#include "cache.h"
2#include "commit.h"
3#include "refs.h"
4
5#define SEEN (1u << 0)
6
7static const char describe_usage[] = "git-describe [--all] <committish>*";
8
9static int all = 0; /* Default to tags only */
10
11static int names = 0, allocs = 0;
12static struct commit_name {
13 const struct commit *commit;
14 char path[];
15} **name_array = NULL;
16
17static struct commit_name *match(struct commit *cmit)
18{
19 int i = names;
20 struct commit_name **p = name_array;
21
22 while (i-- > 0) {
23 struct commit_name *n = *p++;
24 if (n->commit == cmit)
25 return n;
26 }
27 return NULL;
28}
29
30static void add_to_known_names(const char *path, const struct commit *commit)
31{
32 int idx;
33 int len = strlen(path)+1;
34 struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
35
36 name->commit = commit;
37 memcpy(name->path, path, len);
38 idx = names;
39 if (idx >= allocs) {
40 allocs = (idx + 50) * 3 / 2;
41 name_array = xrealloc(name_array, allocs*sizeof(*name_array));
42 }
43 name_array[idx] = name;
44 names = ++idx;
45}
46
47static int get_name(const char *path, const unsigned char *sha1)
48{
49 struct commit *commit = lookup_commit_reference_gently(sha1, 1);
50 if (!commit)
51 return 0;
52 if (!all && strncmp(path, "refs/tags/", 10))
53 return 0;
54 add_to_known_names(path, commit);
55 return 0;
56}
57
58static int compare_names(const void *_a, const void *_b)
59{
60 struct commit_name *a = *(struct commit_name **)_a;
61 struct commit_name *b = *(struct commit_name **)_b;
62 unsigned long a_date = a->commit->date;
63 unsigned long b_date = b->commit->date;
64 return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
65}
66
67static void describe(struct commit *cmit)
68{
69 struct commit_list *list;
70 static int initialized = 0;
71 struct commit_name *n;
72
73 if (!initialized) {
74 initialized = 1;
75 for_each_ref(get_name);
76 qsort(name_array, names, sizeof(*name_array), compare_names);
77 }
78
79 n = match(cmit);
80 if (n) {
81 printf("%s\n", n->path);
82 return;
83 }
84
85 list = NULL;
86 commit_list_insert(cmit, &list);
87 while (list) {
88 struct commit *c = pop_most_recent_commit(&list, SEEN);
89 n = match(c);
90 if (n) {
91 printf("%s-g%.8s\n", n->path, sha1_to_hex(cmit->object.sha1));
92 return;
93 }
94 }
95}
96
97int main(int argc, char **argv)
98{
99 int i;
100
101 for (i = 1; i < argc; i++) {
102 const char *arg = argv[i];
103 unsigned char sha1[20];
104 struct commit *cmit;
105
106 if (!strcmp(arg, "--all")) {
107 all = 1;
108 continue;
109 }
110 if (get_sha1(arg, sha1) < 0)
111 usage(describe_usage);
112 cmit = lookup_commit_reference(sha1);
113 if (!cmit)
114 usage(describe_usage);
115 describe(cmit);
116 }
117 return 0;
118}