describe.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "refs.h"
   4
   5 #define SEEN (1u << 0)
   6
   7 static const char describe_usage[] = "git-describe [--all] <committish>*";
   8
   9 static int all = 0;     /* Default to tags only */
  10
  11 static int names = 0, allocs = 0;
  12 static struct commit_name {
  13         const struct commit *commit;
  14         char path[];
  15 } **name_array = NULL;
  16
  17 static 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
  30 static 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
  47 static 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
  58 static 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
  67 static 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
  97 int 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 }