describe --always: fall back to showing an abbreviated object name

Some callers may find it useful if "git describe" always gave back a
string that can be used as a shorter name for a commit object, rather than
checking its exit status (while squelching its error message, which could
potentially talk about more grave errors that should not be squelched) and
implementing a fallback themselves.

This teaches describe/name-rev a new option, --always, to use an
abbreviated object name when no tags or refs to use is found.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-describe.c b/builtin-describe.c
index 2f1e7ba150098dfa85c8ffe009b318c22bedcbbd..2946457e9adbddd93784a13d1d604686ebf7a548 100644 (file)
--- a/builtin-describe.c
+++ b/builtin-describe.c
@@ -21,6 +21,7 @@ static int longformat;
 static int abbrev = DEFAULT_ABBREV;
 static int max_candidates = 10;
 const char *pattern = NULL;
+static int always;
 
 struct commit_name {
        struct tag *tag;
@@ -250,8 +251,14 @@ static void describe(const char *arg, int last_one)
                }
        }
 
-       if (!match_cnt)
-               die("cannot describe '%s'", sha1_to_hex(cmit->object.sha1));
+       if (!match_cnt) {
+               const unsigned char *sha1 = cmit->object.sha1;
+               if (always) {
+                       printf("%s\n", find_unique_abbrev(sha1, abbrev));
+                       return;
+               }
+               die("cannot describe '%s'", sha1_to_hex(sha1));
+       }
 
        qsort(all_matches, match_cnt, sizeof(all_matches[0]), compare_pt);
 
@@ -305,6 +312,8 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
                            "consider <n> most recent tags (default: 10)"),
                OPT_STRING(0, "match",       &pattern, "pattern",
                           "only consider tags matching <pattern>"),
+               OPT_BOOLEAN(0, "always",     &always,
+                          "show abbreviated commit object as fallback"),
                OPT_END(),
        };
 
@@ -320,11 +329,13 @@ int cmd_describe(int argc, const char **argv, const char *prefix)
                die("--long is incompatible with --abbrev=0");
 
        if (contains) {
-               const char **args = xmalloc((6 + argc) * sizeof(char*));
+               const char **args = xmalloc((7 + argc) * sizeof(char*));
                int i = 0;
                args[i++] = "name-rev";
                args[i++] = "--name-only";
                args[i++] = "--no-undefined";
+               if (always)
+                       args[i++] = "--always";
                if (!all) {
                        args[i++] = "--tags";
                        if (pattern) {

diff --git a/builtin-name-rev.c b/builtin-name-rev.c
index f22c8b5f5da0031657f10ddb827d33a07056e3a5..384da4db13d9ff82b9bd45e6ab26b5dbf925dc22 100644 (file)
--- a/builtin-name-rev.c
+++ b/builtin-name-rev.c
@@ -125,7 +125,7 @@ static int name_ref(const char *path, const unsigned char *sha1, int flags, void
 }
 
 /* returns a static buffer */
-static const char *get_rev_name(struct object *o)
+static const char *get_rev_name(const struct object *o)
 {
        static char buffer[1024];
        struct rev_name *n;
@@ -151,6 +151,26 @@ static const char *get_rev_name(struct object *o)
        }
 }
 
+static void show_name(const struct object *obj,
+                     const char *caller_name,
+                     int always, int allow_undefined, int name_only)
+{
+       const char *name;
+       const unsigned char *sha1 = obj->sha1;
+
+       if (!name_only)
+               printf("%s ", caller_name ? caller_name : sha1_to_hex(sha1));
+       name = get_rev_name(obj);
+       if (name)
+               printf("%s\n", name);
+       else if (allow_undefined)
+               printf("undefined\n");
+       else if (always)
+               printf("%s\n", find_unique_abbrev(sha1, DEFAULT_ABBREV));
+       else
+               die("cannot describe '%s'", sha1_to_hex(sha1));
+}
+
 static char const * const name_rev_usage[] = {
        "git-name-rev [options] ( --all | --stdin | <commit>... )",
        NULL
@@ -159,7 +179,7 @@ static char const * const name_rev_usage[] = {
 int cmd_name_rev(int argc, const char **argv, const char *prefix)
 {
        struct object_array revs = { 0, 0, NULL };
-       int all = 0, transform_stdin = 0, allow_undefined = 1;
+       int all = 0, transform_stdin = 0, allow_undefined = 1, always = 0;
        struct name_ref_data data = { 0, 0, NULL };
        struct option opts[] = {
                OPT_BOOLEAN(0, "name-only", &data.name_only, "print only names (no SHA-1)"),
@@ -170,6 +190,8 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
                OPT_BOOLEAN(0, "all", &all, "list all commits reachable from all refs"),
                OPT_BOOLEAN(0, "stdin", &transform_stdin, "read from stdin"),
                OPT_BOOLEAN(0, "undefined", &allow_undefined, "allow to print `undefined` names"),
+               OPT_BOOLEAN(0, "always",     &always,
+                          "show abbreviated commit object as fallback"),
                OPT_END(),
        };
 
@@ -258,35 +280,14 @@ int cmd_name_rev(int argc, const char **argv, const char *prefix)
                int i, max;
 
                max = get_max_object_index();
-               for (i = 0; i < max; i++) {
-                       struct object * obj = get_indexed_object(i);
-                       const char *name;
-                       if (!obj)
-                               continue;
-                       if (!data.name_only)
-                               printf("%s ", sha1_to_hex(obj->sha1));
-                       name = get_rev_name(obj);
-                       if (name)
-                               printf("%s\n", name);
-                       else if (allow_undefined)
-                               printf("undefined\n");
-                       else
-                               die("cannot describe '%s'", sha1_to_hex(obj->sha1));
-               }
+               for (i = 0; i < max; i++)
+                       show_name(get_indexed_object(i), NULL,
+                                 always, allow_undefined, data.name_only);
        } else {
                int i;
-               for (i = 0; i < revs.nr; i++) {
-                       const char *name;
-                       if (!data.name_only)
-                               printf("%s ", revs.objects[i].name);
-                       name = get_rev_name(revs.objects[i].item);
-                       if (name)
-                               printf("%s\n", name);
-                       else if (allow_undefined)
-                               printf("undefined\n");
-                       else
-                               die("cannot describe '%s'", sha1_to_hex(revs.objects[i].item->sha1));
-               }
+               for (i = 0; i < revs.nr; i++)
+                       show_name(revs.objects[i].item, revs.objects[i].name,
+                                 always, allow_undefined, data.name_only);
        }
 
        return 0;