Add new "git replace" command

This command can only be used now to list replace refs in
"refs/replace/" and to delete them.

The option to list replace refs is "-l".
The option to delete replace refs is "-d".

The behavior should be consistent with how "git tag" and "git branch"
are working.

The code has been copied from "builtin-tag.c" by Kristian Høgsberg
<krh@redhat.com> and Carlos Rica <jasampler@gmail.com> that was itself
based on git-tag.sh and mktag.c by Linus Torvalds.

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

Makefile

@@ -602,6 +602,7 @@ BUILTIN_OBJS += builtin-read-tree.o
 BUILTIN_OBJS += builtin-receive-pack.o
 BUILTIN_OBJS += builtin-reflog.o
 BUILTIN_OBJS += builtin-remote.o
+BUILTIN_OBJS += builtin-replace.o
 BUILTIN_OBJS += builtin-rerere.o
 BUILTIN_OBJS += builtin-reset.o
 BUILTIN_OBJS += builtin-rev-list.o

builtin-replace.c

@@ -0,0 +1,105 @@
+/*
+ * Builtin "git replace"
+ *
+ * Copyright (c) 2008 Christian Couder <chriscool@tuxfamily.org>
+ *
+ * Based on builtin-tag.c by Kristian Høgsberg <krh@redhat.com>
+ * and Carlos Rica <jasampler@gmail.com> that was itself based on
+ * git-tag.sh and mktag.c by Linus Torvalds.
+ */
+
+#include "cache.h"
+#include "builtin.h"
+#include "refs.h"
+#include "parse-options.h"
+
+static const char * const git_replace_usage[] = {
+	"git replace -d <object>...",
+	"git replace -l [<pattern>]",
+	NULL
+};
+
+static int show_reference(const char *refname, const unsigned char *sha1,
+			  int flag, void *cb_data)
+{
+	const char *pattern = cb_data;
+
+	if (!fnmatch(pattern, refname, 0))
+		printf("%s\n", refname);
+
+	return 0;
+}
+
+static int list_replace_refs(const char *pattern)
+{
+	if (pattern == NULL)
+		pattern = "*";
+
+	for_each_replace_ref(show_reference, (void *) pattern);
+
+	return 0;
+}
+
+typedef int (*each_replace_name_fn)(const char *name, const char *ref,
+				    const unsigned char *sha1);
+
+static int for_each_replace_name(const char **argv, each_replace_name_fn fn)
+{
+	const char **p;
+	char ref[PATH_MAX];
+	int had_error = 0;
+	unsigned char sha1[20];
+
+	for (p = argv; *p; p++) {
+		if (snprintf(ref, sizeof(ref), "refs/replace/%s", *p)
+					>= sizeof(ref)) {
+			error("replace ref name too long: %.*s...", 50, *p);
+			had_error = 1;
+			continue;
+		}
+		if (!resolve_ref(ref, sha1, 1, NULL)) {
+			error("replace ref '%s' not found.", *p);
+			had_error = 1;
+			continue;
+		}
+		if (fn(*p, ref, sha1))
+			had_error = 1;
+	}
+	return had_error;
+}
+
+static int delete_replace_ref(const char *name, const char *ref,
+			      const unsigned char *sha1)
+{
+	if (delete_ref(ref, sha1, 0))
+		return 1;
+	printf("Deleted replace ref '%s'\n", name);
+	return 0;
+}
+
+int cmd_replace(int argc, const char **argv, const char *prefix)
+{
+	int list = 0, delete = 0;
+	struct option options[] = {
+		OPT_BOOLEAN('l', NULL, &list, "list replace refs"),
+		OPT_BOOLEAN('d', NULL, &delete, "delete replace refs"),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, options, git_replace_usage, 0);
+
+	if (list && delete)
+		usage_with_options(git_replace_usage, options);
+
+	if (delete) {
+		if (argc < 1)
+			usage_with_options(git_replace_usage, options);
+		return for_each_replace_name(argv, delete_replace_ref);
+	}
+
+	/* List refs, even if "list" is not set */
+	if (argc > 1)
+		usage_with_options(git_replace_usage, options);
+
+	return list_replace_refs(argv[0]);
+}

builtin.h

@@ -112,5 +112,6 @@ extern int cmd_write_tree(int argc, const char **argv, const char *prefix);
 extern int cmd_verify_pack(int argc, const char **argv, const char *prefix);
 extern int cmd_show_ref(int argc, const char **argv, const char *prefix);
 extern int cmd_pack_refs(int argc, const char **argv, const char *prefix);
+extern int cmd_replace(int argc, const char **argv, const char *prefix);
 
 #endif

git.c

@@ -340,6 +340,7 @@ static void handle_internal_command(int argc, const char **argv)
 		{ "receive-pack", cmd_receive_pack },
 		{ "reflog", cmd_reflog, RUN_SETUP },
 		{ "remote", cmd_remote, RUN_SETUP },
+		{ "replace", cmd_replace, RUN_SETUP },
 		{ "repo-config", cmd_config },
 		{ "rerere", cmd_rerere, RUN_SETUP },
 		{ "reset", cmd_reset, RUN_SETUP },

t/t6050-replace.sh

@@ -105,6 +105,18 @@ test_expect_success 'repack, clone and fetch work' '
      cd ..
 '
 
+test_expect_success '"git replace" listing and deleting' '
+     test "$HASH2" = "$(git replace -l)" &&
+     test "$HASH2" = "$(git replace)" &&
+     aa=${HASH2%??????????????????????????????????????} &&
+     test "$HASH2" = "$(git replace -l "$aa*")" &&
+     test_must_fail git replace -d $R &&
+     test_must_fail git replace -d &&
+     test_must_fail git replace -l -d $HASH2 &&
+     git replace -d $HASH2 &&
+     test -z "$(git replace -l)"
+'
+
 #
 #
 test_done