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![Shawn O. Pearce](/assets/img/avatar_default.png)
If a project has a very large number of tags then git-describe will spend a good part of its time looping over the tags testing them one at a time to determine if it matches a given commit. For 10 tags this is not a big deal, but for hundreds of tags the time could become considerable if we don't find an exact match for the input commit and we need to walk back along the history chain. Signed-off-by: Shawn O. Pearce <spearce@spearce.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
241 lines
5.5 KiB
C
241 lines
5.5 KiB
C
#include "cache.h"
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#include "commit.h"
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#include "tag.h"
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#include "refs.h"
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#include "diff.h"
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#include "diffcore.h"
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#include "revision.h"
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#include "builtin.h"
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static const char describe_usage[] =
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"git-describe [--all] [--tags] [--abbrev=<n>] <committish>*";
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static int all; /* Default to annotated tags only */
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static int tags; /* But allow any tags if --tags is specified */
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static int abbrev = DEFAULT_ABBREV;
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static unsigned int names[256], allocs[256];
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static struct commit_name {
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struct commit *commit;
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int prio; /* annotated tag = 2, tag = 1, head = 0 */
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char path[FLEX_ARRAY]; /* more */
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} **name_array[256];
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static struct commit_name *match(struct commit *cmit)
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{
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unsigned char m = cmit->object.sha1[0];
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unsigned int i = names[m];
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struct commit_name **p = name_array[m];
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while (i-- > 0) {
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struct commit_name *n = *p++;
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if (n->commit == cmit)
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return n;
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}
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return NULL;
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}
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static void add_to_known_names(const char *path,
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struct commit *commit,
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int prio)
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{
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int idx;
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int len = strlen(path)+1;
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struct commit_name *name = xmalloc(sizeof(struct commit_name) + len);
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unsigned char m = commit->object.sha1[0];
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name->commit = commit;
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name->prio = prio;
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memcpy(name->path, path, len);
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idx = names[m];
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if (idx >= allocs[m]) {
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allocs[m] = (idx + 50) * 3 / 2;
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name_array[m] = xrealloc(name_array[m],
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allocs[m] * sizeof(*name_array));
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}
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name_array[m][idx] = name;
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names[m] = ++idx;
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}
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static int get_name(const char *path, const unsigned char *sha1, int flag, void *cb_data)
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{
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struct commit *commit = lookup_commit_reference_gently(sha1, 1);
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struct object *object;
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int prio;
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if (!commit)
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return 0;
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object = parse_object(sha1);
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/* If --all, then any refs are used.
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* If --tags, then any tags are used.
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* Otherwise only annotated tags are used.
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*/
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if (!strncmp(path, "refs/tags/", 10)) {
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if (object->type == OBJ_TAG)
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prio = 2;
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else
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prio = 1;
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}
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else
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prio = 0;
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if (!all) {
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if (!prio)
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return 0;
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if (!tags && prio < 2)
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return 0;
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}
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add_to_known_names(all ? path + 5 : path + 10, commit, prio);
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return 0;
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}
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static int compare_names(const void *_a, const void *_b)
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{
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struct commit_name *a = *(struct commit_name **)_a;
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struct commit_name *b = *(struct commit_name **)_b;
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unsigned long a_date = a->commit->date;
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unsigned long b_date = b->commit->date;
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if (a->prio != b->prio)
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return b->prio - a->prio;
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return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1;
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}
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struct possible_tag {
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struct possible_tag *next;
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struct commit_name *name;
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unsigned long depth;
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};
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static void describe(const char *arg, int last_one)
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{
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unsigned char sha1[20];
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struct commit *cmit;
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struct commit_list *list;
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static int initialized = 0;
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struct commit_name *n;
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struct possible_tag *all_matches, *min_match, *cur_match;
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if (get_sha1(arg, sha1))
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die("Not a valid object name %s", arg);
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cmit = lookup_commit_reference(sha1);
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if (!cmit)
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die("%s is not a valid '%s' object", arg, commit_type);
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if (!initialized) {
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unsigned int m;
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initialized = 1;
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for_each_ref(get_name, NULL);
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for (m = 0; m < ARRAY_SIZE(name_array); m++)
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qsort(name_array[m], names[m],
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sizeof(*name_array[m]), compare_names);
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}
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n = match(cmit);
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if (n) {
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printf("%s\n", n->path);
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return;
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}
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list = NULL;
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all_matches = NULL;
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cur_match = NULL;
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commit_list_insert(cmit, &list);
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while (list) {
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struct commit *c = pop_commit(&list);
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struct commit_list *parents = c->parents;
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n = match(c);
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if (n) {
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struct possible_tag *p = xmalloc(sizeof(*p));
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p->name = n;
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p->next = NULL;
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if (cur_match)
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cur_match->next = p;
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else
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all_matches = p;
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cur_match = p;
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if (n->prio == 2)
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continue;
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}
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while (parents) {
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struct commit *p = parents->item;
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parse_commit(p);
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if (!(p->object.flags & SEEN)) {
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p->object.flags |= SEEN;
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insert_by_date(p, &list);
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}
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parents = parents->next;
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}
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}
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if (!all_matches)
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die("cannot describe '%s'", sha1_to_hex(cmit->object.sha1));
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min_match = NULL;
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for (cur_match = all_matches; cur_match; cur_match = cur_match->next) {
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struct rev_info revs;
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struct commit *tagged = cur_match->name->commit;
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clear_commit_marks(cmit, -1);
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init_revisions(&revs, NULL);
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tagged->object.flags |= UNINTERESTING;
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add_pending_object(&revs, &tagged->object, NULL);
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add_pending_object(&revs, &cmit->object, NULL);
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prepare_revision_walk(&revs);
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cur_match->depth = 0;
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while ((!min_match || cur_match->depth < min_match->depth)
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&& get_revision(&revs))
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cur_match->depth++;
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if (!min_match || (cur_match->depth < min_match->depth
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&& cur_match->name->prio >= min_match->name->prio))
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min_match = cur_match;
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free_commit_list(revs.commits);
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}
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printf("%s-g%s\n", min_match->name->path,
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find_unique_abbrev(cmit->object.sha1, abbrev));
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if (!last_one) {
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for (cur_match = all_matches; cur_match; cur_match = min_match) {
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min_match = cur_match->next;
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free(cur_match);
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}
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clear_commit_marks(cmit, SEEN);
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}
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}
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int cmd_describe(int argc, const char **argv, const char *prefix)
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{
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int i;
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for (i = 1; i < argc; i++) {
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const char *arg = argv[i];
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if (*arg != '-')
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break;
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else if (!strcmp(arg, "--all"))
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all = 1;
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else if (!strcmp(arg, "--tags"))
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tags = 1;
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else if (!strncmp(arg, "--abbrev=", 9)) {
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abbrev = strtoul(arg + 9, NULL, 10);
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if (abbrev < MINIMUM_ABBREV || 40 < abbrev)
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abbrev = DEFAULT_ABBREV;
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}
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else
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usage(describe_usage);
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}
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save_commit_buffer = 0;
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if (argc <= i)
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describe("HEAD", 1);
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else
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while (i < argc) {
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describe(argv[i], (i == argc - 1));
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i++;
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}
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return 0;
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}
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