Exec git programs without using PATH.
[git.git] / describe.c
1 #include "cache.h"
2 #include "commit.h"
3 #include "tag.h"
4 #include "refs.h"
5
6 #define SEEN (1u << 0)
7
8 static const char describe_usage[] =
9 "git-describe [--all] [--tags] [--abbrev=<n>] <committish>*";
10
11 static int all = 0;     /* Default to annotated tags only */
12 static int tags = 0;    /* But allow any tags if --tags is specified */
13
14 #define DEFAULT_ABBREV 8 /* maybe too many */
15 static int abbrev = DEFAULT_ABBREV;
16
17 static int names = 0, allocs = 0;
18 static struct commit_name {
19         const struct commit *commit;
20         int prio; /* annotated tag = 2, tag = 1, head = 0 */
21         char path[FLEX_ARRAY]; /* more */
22 } **name_array = NULL;
23
24 static struct commit_name *match(struct commit *cmit)
25 {
26         int i = names;
27         struct commit_name **p = name_array;
28
29         while (i-- > 0) {
30                 struct commit_name *n = *p++;
31                 if (n->commit == cmit)
32                         return n;
33         }
34         return NULL;
35 }
36
37 static void add_to_known_names(const char *path,
38                                const struct commit *commit,
39                                int prio)
40 {
41         int idx;
42         int len = strlen(path)+1;
43         struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
44
45         name->commit = commit;
46         name->prio = prio; 
47         memcpy(name->path, path, len);
48         idx = names;
49         if (idx >= allocs) {
50                 allocs = (idx + 50) * 3 / 2;
51                 name_array = xrealloc(name_array, allocs*sizeof(*name_array));
52         }
53         name_array[idx] = name;
54         names = ++idx;
55 }
56
57 static int get_name(const char *path, const unsigned char *sha1)
58 {
59         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
60         struct object *object;
61         int prio;
62
63         if (!commit)
64                 return 0;
65         object = parse_object(sha1);
66         /* If --all, then any refs are used.
67          * If --tags, then any tags are used.
68          * Otherwise only annotated tags are used.
69          */
70         if (!strncmp(path, "refs/tags/", 10)) {
71                 if (object->type == tag_type)
72                         prio = 2;
73                 else
74                         prio = 1;
75         }
76         else
77                 prio = 0;
78
79         if (!all) {
80                 if (!prio)
81                         return 0;
82                 if (!tags && prio < 2)
83                         return 0;
84         }
85         add_to_known_names(all ? path + 5 : path + 10, commit, prio);
86         return 0;
87 }
88
89 static int compare_names(const void *_a, const void *_b)
90 {
91         struct commit_name *a = *(struct commit_name **)_a;
92         struct commit_name *b = *(struct commit_name **)_b;
93         unsigned long a_date = a->commit->date;
94         unsigned long b_date = b->commit->date;
95
96         if (a->prio != b->prio)
97                 return b->prio - a->prio;
98         return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
99 }
100
101 static void describe(char *arg)
102 {
103         unsigned char sha1[20];
104         struct commit *cmit;
105         struct commit_list *list;
106         static int initialized = 0;
107         struct commit_name *n;
108
109         if (get_sha1(arg, sha1) < 0)
110                 usage(describe_usage);
111         cmit = lookup_commit_reference(sha1);
112         if (!cmit)
113                 usage(describe_usage);
114
115         if (!initialized) {
116                 initialized = 1;
117                 for_each_ref(get_name);
118                 qsort(name_array, names, sizeof(*name_array), compare_names);
119         }
120
121         n = match(cmit);
122         if (n) {
123                 printf("%s\n", n->path);
124                 return;
125         }
126
127         list = NULL;
128         commit_list_insert(cmit, &list);
129         while (list) {
130                 struct commit *c = pop_most_recent_commit(&list, SEEN);
131                 n = match(c);
132                 if (n) {
133                         printf("%s-g%s\n", n->path,
134                                find_unique_abbrev(cmit->object.sha1, abbrev));
135                         break;
136                 }
137         }
138         clear_commit_marks(cmit, SEEN);
139 }
140
141 int main(int argc, char **argv)
142 {
143         int i;
144
145         for (i = 1; i < argc; i++) {
146                 const char *arg = argv[i];
147
148                 if (*arg != '-')
149                         break;
150                 else if (!strcmp(arg, "--all"))
151                         all = 1;
152                 else if (!strcmp(arg, "--tags"))
153                         tags = 1;
154                 else if (!strncmp(arg, "--abbrev=", 9)) {
155                         abbrev = strtoul(arg + 9, NULL, 10);
156                         if (abbrev < 4 || 40 <= abbrev)
157                                 abbrev = DEFAULT_ABBREV;
158                 }
159                 else
160                         usage(describe_usage);
161         }
162
163         if (i == argc)
164                 describe("HEAD");
165         else
166                 while (i < argc)
167                         describe(argv[i++]);
168
169         return 0;
170 }