[PATCH 4/5] make get_short_ref a public function
Often we want to shorten a full ref name to something "prettier" to show a user. For example, "refs/heads/master" is often shown simply as "master", or "refs/remotes/origin/master" is shown as "origin/master".
Many places in the code use a very simple formula: skip common prefixes like refs/heads, refs/remotes, etc. This is codified in the prettify_ref function.
for-each-ref has a more correct (but more expensive) approach: consider the ref lookup rules, and try shortening as much as possible while remaining unambiguous.
This patch makes the latter strategy globally available as shorten_unambiguous_ref.
Signed-off-by: Jeff King <peff@peff.net>
---
Actually, I am not quite sure that this function is "more correct". It
looks at the rev-parsing rules as a hierarchy, so if you have
"refs/remotes/foo" and "refs/heads/foo", then it will abbreviate the
first to "remotes/foo" (as expected) and the latter to just "foo".
This is technically correct, as "refs/heads/foo" will be selected by "foo", but it will warn about ambiguity. Should we actually try to avoid reporting refs which would be ambiguous?
Should this simply replace prettify_ref (and other places which should be using prettify_ref but aren't)? It is definitely more expensive, as it has to resolve refs to look for ambiguities, but I don't know if we care in most code paths.
builtin-for-each-ref.c | 105 +-----------------------------------------------
refs.c | 99 +++++++++++++++++++++++++++++++++++++++++++++
refs.h | 1 +
3 files changed, 101 insertions(+), 104 deletions(-)
Show changes to 3 files +101 −104
builtin-for-each-ref.c, refs.c, refs.h
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index 277d1fb..8c82484 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -546,109 +546,6 @@ static void grab_values(struct atom_value *val, int deref, struct object *obj, v
}
/*
- * 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;
-}
-
-/*
- * Shorten the refname to an non-ambiguous form
- */
-static char *get_short_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);
-}
-
-
-/*
* Parse the object referred by ref, and grab needed value.
*/
static void populate_value(struct refinfo *ref)
@@ -704,7 +601,7 @@ static void populate_value(struct refinfo *ref)
if (formatp) {
formatp++;
if (!strcmp(formatp, "short"))
- refname = get_short_ref(refname);
+ refname = shorten_unambiguous_ref(refname);
else
die("unknown %.*s format %s",
formatp - name, name, formatp);
diff --git a/refs.c b/refs.c
index 59c373f..1e5e7b4 100644
--- a/refs.c
+++ b/refs.c
@@ -1652,3 +1652,102 @@ 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);
+}
diff --git a/refs.h b/refs.h
index 68c2d16..2d0f961 100644
--- a/refs.h
+++ b/refs.h
@@ -80,6 +80,7 @@ extern int for_each_reflog(each_ref_fn, void *);
extern int check_ref_format(const char *target);
extern const char *prettify_ref(const struct ref *ref);
+extern char *shorten_unambiguous_ref(const char *ref);
/** rename ref, return 0 on success **/
extern int rename_ref(const char *oldref, const char *newref, const char *logmsg);
--
1.6.2.2.450.gd6aa9.dirty
Jeff King
