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-rw-r--r--refs.c99
1 files changed, 99 insertions, 0 deletions
diff --git a/refs.c b/refs.c
index 9ccaf40..82afb87 100644
--- a/refs.c
+++ b/refs.c
@@ -1657,3 +1657,102 @@ struct ref *find_ref_by_name(const struct ref *list, const char *name)
return (struct ref *)list;
return NULL;
}
+
+/*
+ * generate a format suitable for scanf from a ref_rev_parse_rules
+ * rule, that is replace the "%.*s" spec with a "%s" spec
+ */
+static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
+{
+ char *spec;
+
+ spec = strstr(rule, "%.*s");
+ if (!spec || strstr(spec + 4, "%.*s"))
+ die("invalid rule in ref_rev_parse_rules: %s", rule);
+
+ /* copy all until spec */
+ strncpy(scanf_fmt, rule, spec - rule);
+ scanf_fmt[spec - rule] = '\0';
+ /* copy new spec */
+ strcat(scanf_fmt, "%s");
+ /* copy remaining rule */
+ strcat(scanf_fmt, spec + 4);
+
+ return;
+}
+
+char *shorten_unambiguous_ref(const char *ref)
+{
+ int i;
+ static char **scanf_fmts;
+ static int nr_rules;
+ char *short_name;
+
+ /* pre generate scanf formats from ref_rev_parse_rules[] */
+ if (!nr_rules) {
+ size_t total_len = 0;
+
+ /* the rule list is NULL terminated, count them first */
+ for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
+ /* no +1 because strlen("%s") < strlen("%.*s") */
+ total_len += strlen(ref_rev_parse_rules[nr_rules]);
+
+ scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
+
+ total_len = 0;
+ for (i = 0; i < nr_rules; i++) {
+ scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
+ + total_len;
+ gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
+ total_len += strlen(ref_rev_parse_rules[i]);
+ }
+ }
+
+ /* bail out if there are no rules */
+ if (!nr_rules)
+ return xstrdup(ref);
+
+ /* buffer for scanf result, at most ref must fit */
+ short_name = xstrdup(ref);
+
+ /* skip first rule, it will always match */
+ for (i = nr_rules - 1; i > 0 ; --i) {
+ int j;
+ int short_name_len;
+
+ if (1 != sscanf(ref, scanf_fmts[i], short_name))
+ continue;
+
+ short_name_len = strlen(short_name);
+
+ /*
+ * check if the short name resolves to a valid ref,
+ * but use only rules prior to the matched one
+ */
+ for (j = 0; j < i; j++) {
+ const char *rule = ref_rev_parse_rules[j];
+ unsigned char short_objectname[20];
+ char refname[PATH_MAX];
+
+ /*
+ * the short name is ambiguous, if it resolves
+ * (with this previous rule) to a valid ref
+ * read_ref() returns 0 on success
+ */
+ mksnpath(refname, sizeof(refname),
+ rule, short_name_len, short_name);
+ if (!read_ref(refname, short_objectname))
+ break;
+ }
+
+ /*
+ * short name is non-ambiguous if all previous rules
+ * haven't resolved to a valid ref
+ */
+ if (j == i)
+ return short_name;
+ }
+
+ free(short_name);
+ return xstrdup(ref);
+}