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[];
  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(struct commit *cmit)
 102 {
 103         struct commit_list *list;
 104         static int initialized = 0;
 105         struct commit_name *n;
 106
 107         if (!initialized) {
 108                 initialized = 1;
 109                 for_each_ref(get_name);
 110                 qsort(name_array, names, sizeof(*name_array), compare_names);
 111         }
 112
 113         n = match(cmit);
 114         if (n) {
 115                 printf("%s\n", n->path);
 116                 return;
 117         }
 118
 119         list = NULL;
 120         commit_list_insert(cmit, &list);
 121         while (list) {
 122                 struct commit *c = pop_most_recent_commit(&list, SEEN);
 123                 n = match(c);
 124                 if (n) {
 125                         printf("%s-g%s\n", n->path,
 126                                find_unique_abbrev(cmit->object.sha1, abbrev));
 127                         return;
 128                 }
 129         }
 130 }
 131
 132 int main(int argc, char **argv)
 133 {
 134         int i;
 135
 136         for (i = 1; i < argc; i++) {
 137                 const char *arg = argv[i];
 138                 unsigned char sha1[20];
 139                 struct commit *cmit;
 140
 141                 if (!strcmp(arg, "--all")) {
 142                         all = 1;
 143                         continue;
 144                 }
 145                 if (!strcmp(arg, "--tags")) {
 146                         tags = 1;
 147                         continue;
 148                 }
 149                 if (!strncmp(arg, "--abbrev=", 9)) {
 150                         abbrev = strtoul(arg + 9, NULL, 10);
 151                         if (abbrev < 4 || 40 <= abbrev)
 152                                 abbrev = DEFAULT_ABBREV;
 153                         continue;
 154                 }
 155                 if (get_sha1(arg, sha1) < 0)
 156                         usage(describe_usage);
 157                 cmit = lookup_commit_reference(sha1);
 158                 if (!cmit)
 159                         usage(describe_usage);
 160                 describe(cmit);
 161         }
 162         return 0;
 163 }