builtin-replace: teach "git replace" to actually replace

Teach the syntax: "git replace <object> <replacement>", so that
"git replace" can now create replace refs. These replace refs
will be used by read_sha1_file to substitute <object> with
<replacement> for most of the commands.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-replace.c b/builtin-replace.c
index b5c40aa22a0b4e66daf46708c33e6b96051f1dda..e3767b9661f20660498add7b7fcd8928094a36d6 100644 (file)
--- a/builtin-replace.c
+++ b/builtin-replace.c
@@ -14,6 +14,7 @@
 #include "parse-options.h"
 
 static const char * const git_replace_usage[] = {
+       "git replace [-f] <object> <replacement>",
        "git replace -d <object>...",
        "git replace -l [<pattern>]",
        NULL
@@ -77,12 +78,46 @@ static int delete_replace_ref(const char *name, const char *ref,
        return 0;
 }
 
+static int replace_object(const char *object_ref, const char *replace_ref,
+                         int force)
+{
+       unsigned char object[20], prev[20], repl[20];
+       char ref[PATH_MAX];
+       struct ref_lock *lock;
+
+       if (get_sha1(object_ref, object))
+               die("Failed to resolve '%s' as a valid ref.", object_ref);
+       if (get_sha1(replace_ref, repl))
+               die("Failed to resolve '%s' as a valid ref.", replace_ref);
+
+       if (snprintf(ref, sizeof(ref),
+                    "refs/replace/%s",
+                    sha1_to_hex(object)) > sizeof(ref) - 1)
+               die("replace ref name too long: %.*s...", 50, ref);
+       if (check_ref_format(ref))
+               die("'%s' is not a valid ref name.", ref);
+
+       if (!resolve_ref(ref, prev, 1, NULL))
+               hashclr(prev);
+       else if (!force)
+               die("replace ref '%s' already exists", ref);
+
+       lock = lock_any_ref_for_update(ref, prev, 0);
+       if (!lock)
+               die("%s: cannot lock the ref", ref);
+       if (write_ref_sha1(lock, repl, NULL) < 0)
+               die("%s: cannot update the ref", ref);
+
+       return 0;
+}
+
 int cmd_replace(int argc, const char **argv, const char *prefix)
 {
-       int list = 0, delete = 0;
+       int list = 0, delete = 0, force = 0;
        struct option options[] = {
                OPT_BOOLEAN('l', NULL, &list, "list replace refs"),
                OPT_BOOLEAN('d', NULL, &delete, "delete replace refs"),
+               OPT_BOOLEAN('f', NULL, &force, "replace the ref if it exists"),
                OPT_END()
        };
 
@@ -91,15 +126,28 @@ int cmd_replace(int argc, const char **argv, const char *prefix)
        if (list && delete)
                usage_with_options(git_replace_usage, options);
 
+       if (force && (list || delete))
+               usage_with_options(git_replace_usage, options);
+
+       /* Delete refs */
        if (delete) {
                if (argc < 1)
                        usage_with_options(git_replace_usage, options);
                return for_each_replace_name(argv, delete_replace_ref);
        }
 
+       /* Replace object */
+       if (!list && argc) {
+               if (argc != 2)
+                       usage_with_options(git_replace_usage, options);
+               return replace_object(argv[0], argv[1], force);
+       }
+
        /* List refs, even if "list" is not set */
        if (argc > 1)
                usage_with_options(git_replace_usage, options);
+       if (force)
+               usage_with_options(git_replace_usage, options);
 
        return list_replace_refs(argv[0]);
 }

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index bf4c93f7f84be0fd6c7590aaf0d3d3847de05ef7..448a19a5ecf4bf1ca0d5e79f5beeb12010b1d4d9 100755 (executable)
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -114,9 +114,19 @@ test_expect_success '"git replace" listing and deleting' '
      test_must_fail git replace -d &&
      test_must_fail git replace -l -d $HASH2 &&
      git replace -d $HASH2 &&
+     git show $HASH2 | grep "A U Thor" &&
      test -z "$(git replace -l)"
 '
 
+test_expect_success '"git replace" replacing' '
+     git replace $HASH2 $R &&
+     git show $HASH2 | grep "O Thor" &&
+     test_must_fail git replace $HASH2 $R &&
+     git replace -f $HASH2 $R &&
+     test_must_fail git replace -f &&
+     test "$HASH2" = "$(git replace)"
+'
+
 #
 #
 test_done