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[] = "git-describe [--all] <committish>*";
   9
  10 static int all = 0;     /* Default to annotated tags only */
  11
  12 static int names = 0, allocs = 0;
  13 static struct commit_name {
  14         const struct commit *commit;
  15         char path[];
  16 } **name_array = NULL;
  17
  18 static struct commit_name *match(struct commit *cmit)
  19 {
  20         int i = names;
  21         struct commit_name **p = name_array;
  22
  23         while (i-- > 0) {
  24                 struct commit_name *n = *p++;
  25                 if (n->commit == cmit)
  26                         return n;
  27         }
  28         return NULL;
  29 }
  30
  31 static void add_to_known_names(const char *path, const struct commit *commit)
  32 {
  33         int idx;
  34         int len = strlen(path)+1;
  35         struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
  36
  37         name->commit = commit;
  38         memcpy(name->path, path, len);
  39         idx = names;
  40         if (idx >= allocs) {
  41                 allocs = (idx + 50) * 3 / 2;
  42                 name_array = xrealloc(name_array, allocs*sizeof(*name_array));
  43         }
  44         name_array[idx] = name;
  45         names = ++idx;
  46 }
  47
  48 static int get_name(const char *path, const unsigned char *sha1)
  49 {
  50         struct commit *commit = lookup_commit_reference_gently(sha1, 1);
  51         if (!commit)
  52                 return 0;
  53         if (!all) {
  54                 struct object *object;
  55                 if (strncmp(path, "refs/tags/", 10))
  56                         return 0;
  57                 object = parse_object(sha1);
  58                 if (object->type != tag_type)
  59                         return 0;
  60         }
  61         add_to_known_names(all ? path : path + 10, commit);
  62         return 0;
  63 }
  64
  65 static int compare_names(const void *_a, const void *_b)
  66 {
  67         struct commit_name *a = *(struct commit_name **)_a;
  68         struct commit_name *b = *(struct commit_name **)_b;
  69         unsigned long a_date = a->commit->date;
  70         unsigned long b_date = b->commit->date;
  71         return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
  72 }
  73
  74 static void describe(struct commit *cmit)
  75 {
  76         struct commit_list *list;
  77         static int initialized = 0;
  78         struct commit_name *n;
  79
  80         if (!initialized) {
  81                 initialized = 1;
  82                 for_each_ref(get_name);
  83                 qsort(name_array, names, sizeof(*name_array), compare_names);
  84         }
  85
  86         n = match(cmit);
  87         if (n) {
  88                 printf("%s\n", n->path);
  89                 return;
  90         }
  91
  92         list = NULL;
  93         commit_list_insert(cmit, &list);
  94         while (list) {
  95                 struct commit *c = pop_most_recent_commit(&list, SEEN);
  96                 n = match(c);
  97                 if (n) {
  98                         printf("%s-g%.8s\n", n->path, sha1_to_hex(cmit->object.sha1));
  99                         return;
 100                 }
 101         }
 102 }
 103
 104 int main(int argc, char **argv)
 105 {
 106         int i;
 107
 108         for (i = 1; i < argc; i++) {
 109                 const char *arg = argv[i];
 110                 unsigned char sha1[20];
 111                 struct commit *cmit;
 112
 113                 if (!strcmp(arg, "--all")) {
 114                         all = 1;
 115                         continue;
 116                 }
 117                 if (get_sha1(arg, sha1) < 0)
 118                         usage(describe_usage);
 119                 cmit = lookup_commit_reference(sha1);
 120                 if (!cmit)
 121                         usage(describe_usage);
 122                 describe(cmit);
 123         }
 124         return 0;
 125 }