[PATCH] branch as a builtin (again)

["Kristian Høgsberg" <hoegsberg@gmail.com>]

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Hi,

I sent a patch to rewrite branch in C and make it a builtin a couple
of months ago.  Junio had a few comments about the patch that I now
finally had the time to address.  One of the problems was that
merge-base didn't clean up its state, which has now been fixed.
Here's the updated version.

Signed-off-by: Kristian Høgsberg <krh@redhat.com>

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commit 8153d336ad9643507922932a2ac2277073c66432
Author: Kristian Høgsberg <krh@redhat.com>
Date:   Sun Aug 20 17:04:14 2006 -0400

    Rewrite branch in C and make it a builtin.

diff --git a/Makefile b/Makefile
index 23cd8a0..adf043e 100644
--- a/Makefile
+++ b/Makefile
@@ -149,7 +149,7 @@ SPARSE_FLAGS = -D__BIG_ENDIAN__ -D__powe
 ### --- END CONFIGURATION SECTION ---
 
 SCRIPT_SH = \
-	git-bisect.sh git-branch.sh git-checkout.sh \
+	git-bisect.sh git-checkout.sh \
 	git-cherry.sh git-clean.sh git-clone.sh git-commit.sh \
 	git-fetch.sh \
 	git-ls-remote.sh \
@@ -253,6 +253,7 @@ LIB_OBJS = \
 BUILTIN_OBJS = \
 	builtin-add.o \
 	builtin-apply.o \
+	builtin-branch.o \
 	builtin-cat-file.o \
 	builtin-checkout-index.o \
 	builtin-check-ref-format.o \
diff --git a/builtin-branch.c b/builtin-branch.c
new file mode 100644
index 0000000..25c6313
--- /dev/null
+++ b/builtin-branch.c
@@ -0,0 +1,170 @@
+/*
+ * Builtin "git branch"
+ *
+ * Copyright (c) 2006 Kristian Høgsberg <krh@redhat.com>
+ * Based on git-branch.sh by Junio C Hamano.
+ */
+
+#include "cache.h"
+#include "refs.h"
+#include "commit.h"
+#include "builtin.h"
+
+static const char builtin_branch_usage[] =
+    "git-branch [(-d | -D) <branchname>] | [[-f] <branchname> [<start-point>]] | -r";
+
+
+static int remote_only = 0;
+static const char *head;
+static unsigned char head_sha1[20];
+
+static int in_merge_bases(const unsigned char *sha1,
+			  struct commit *rev1,
+			  struct commit *rev2)
+{
+	struct commit_list *bases, *b;
+
+	bases = get_merge_bases(rev1, rev2, 1);
+	for (b = bases; b != NULL; b = b->next) {
+		if (!hashcmp(sha1, b->item->object.sha1)) {
+			free_commit_list(bases);
+			return 1;
+		}
+	}
+
+	free_commit_list(bases);
+	return 0;
+}
+
+static void delete_branches(int argc, const char **argv, int force)
+{
+	struct commit *rev1, *rev2;
+	unsigned char sha1[20];
+	const char *p, *name;
+	int i;
+
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(head, argv[i]))
+			die("Cannot delete the branch you are currently on.");
+
+		name = git_path("refs/heads/%s", argv[i]);
+		p = resolve_ref(name, sha1, 1);
+		if (p == NULL)
+			die("Branch '%s' not found.", argv[i]);
+
+		rev1 = lookup_commit_reference(sha1);
+		rev2 = lookup_commit_reference(head_sha1);
+		if (!rev1 || !rev2)
+			die("Couldn't look up commit objects.");
+
+		/* This checks wether the merge bases of branch and
+		 * HEAD contains branch -- which means that the HEAD
+		 * contains everything in both.
+		 */
+
+		if (!force &&
+		    !in_merge_bases(sha1, rev1, rev2)) {
+			fprintf(stderr,
+				"The branch '%s' is not a strict subset of your current HEAD.\n"
+				"If you are sure you want to delete it, run 'git branch -D %s'.\n",
+				argv[i], argv[i]);
+			exit(1);
+		}
+
+		unlink(name);
+		printf("Deleted branch %s.\n", argv[i]);
+	}
+}
+
+static int show_reference(const char *refname, const unsigned char *sha1)
+{
+	int is_head = !strcmp(refname, head);
+
+	printf("%c %s\n", (is_head ? '*' : ' '), refname);
+
+	return 0;
+}
+
+static void create_branch (const char *name, const char *start, int force)
+{
+	struct ref_lock *lock;
+	unsigned char sha1[20];
+	char ref[PATH_MAX];
+
+	snprintf(ref, sizeof ref, "refs/heads/%s", name);
+	if (check_ref_format(ref + 5))
+		die("'%s' is not a valid branch name.", name);
+
+	if (resolve_ref(ref, sha1, 1)) {
+		if (!force)
+			die("A branch named '%s' already exists.", name);
+		else if (!strcmp(head, name))
+			die("Cannot force update the current branch.");
+	}
+
+	if (get_sha1(start, sha1))
+		die("Not a valid branch point: '%s'", start);
+
+	lock = lock_any_ref_for_update(ref, NULL, 0);
+	if (!lock)
+		die("Failed to lock ref for update: %s.", strerror(errno));
+	if (write_ref_sha1(lock, sha1, NULL) < 0)
+		die("Failed to write ref: %s.", strerror(errno));
+}
+
+int cmd_branch(int argc, const char **argv, const char *prefix)
+{
+	int delete = 0, force_delete = 0, force_create = 0;
+	int i, prefix_length;
+	const char *p;
+
+	git_config(git_default_config);
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+
+		if (arg[0] != '-')
+			break;
+		if (!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		if (!strcmp(arg, "-d")) {
+			delete = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-D")) {
+			delete = 1;
+			force_delete = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-f")) {
+			force_create = 1;
+			continue;
+		}
+		if (!strcmp(arg, "-r")) {
+			remote_only = 1;
+			continue;
+		}
+		die(builtin_branch_usage);
+	}
+
+	prefix_length = strlen(git_path("refs/heads/"));
+	p = resolve_ref(git_path("HEAD"), head_sha1, 0);
+	if (!p)
+		die("Failed to resolve HEAD as a valid ref");
+	head = strdup(p + prefix_length);
+
+	if (delete)
+		delete_branches(argc - i, argv + i, force_delete);
+	else if (i == argc && remote_only)
+		for_each_remote_ref(show_reference);
+	else if (i == argc)
+		for_each_branch_ref(show_reference);
+	else if (argc - i == 1)
+		create_branch (argv[i], head, force_create);
+	else
+		create_branch (argv[i], argv[i + 1], force_create);
+
+	return 0;
+}
diff --git a/builtin.h b/builtin.h
index ade58c4..eb28986 100644
--- a/builtin.h
+++ b/builtin.h
@@ -15,6 +15,7 @@ extern int write_tree(unsigned char *sha
 
 extern int cmd_add(int argc, const char **argv, const char *prefix);
 extern int cmd_apply(int argc, const char **argv, const char *prefix);
+extern int cmd_branch(int argc, const char **argv, const char *prefix);
 extern int cmd_cat_file(int argc, const char **argv, const char *prefix);
 extern int cmd_checkout_index(int argc, const char **argv, const char *prefix);
 extern int cmd_check_ref_format(int argc, const char **argv, const char *prefix);
diff --git a/git-branch.sh b/git-branch.sh
deleted file mode 100755
index e0501ec..0000000
--- a/git-branch.sh
+++ /dev/null
@@ -1,130 +0,0 @@
-#!/bin/sh
-
-USAGE='[-l] [(-d | -D) <branchname>] | [[-f] <branchname> [<start-point>]] | -r'
-LONG_USAGE='If no arguments, show available branches and mark current branch with a star.
-If one argument, create a new branch <branchname> based off of current HEAD.
-If two arguments, create a new branch <branchname> based off of <start-point>.'
-
-SUBDIRECTORY_OK='Yes'
-. git-sh-setup
-
-headref=$(git-symbolic-ref HEAD | sed -e 's|^refs/heads/||')
-
-delete_branch () {
-    option="$1"
-    shift
-    for branch_name
-    do
-	case ",$headref," in
-	",$branch_name,")
-	    die "Cannot delete the branch you are on." ;;
-	,,)
-	    die "What branch are you on anyway?" ;;
-	esac
-	branch=$(cat "$GIT_DIR/refs/heads/$branch_name") &&
-	    branch=$(git-rev-parse --verify "$branch^0") ||
-		die "Seriously, what branch are you talking about?"
-	case "$option" in
-	-D)
-	    ;;
-	*)
-	    mbs=$(git-merge-base -a "$branch" HEAD | tr '\012' ' ')
-	    case " $mbs " in
-	    *' '$branch' '*)
-		# the merge base of branch and HEAD contains branch --
-		# which means that the HEAD contains everything in both.
-		;;
-	    *)
-		echo >&2 "The branch '$branch_name' is not a strict subset of your current HEAD.
-If you are sure you want to delete it, run 'git branch -D $branch_name'."
-		exit 1
-		;;
-	    esac
-	    ;;
-	esac
-	rm -f "$GIT_DIR/logs/refs/heads/$branch_name"
-	rm -f "$GIT_DIR/refs/heads/$branch_name"
-	echo "Deleted branch $branch_name."
-    done
-    exit 0
-}
-
-ls_remote_branches () {
-    git-rev-parse --symbolic --all |
-    sed -ne 's|^refs/\(remotes/\)|\1|p' |
-    sort
-}
-
-force=
-create_log=
-while case "$#,$1" in 0,*) break ;; *,-*) ;; *) break ;; esac
-do
-	case "$1" in
-	-d | -D)
-		delete_branch "$@"
-		exit
-		;;
-	-r)
-		ls_remote_branches
-		exit
-		;;
-	-f)
-		force="$1"
-		;;
-	-l)
-		create_log="yes"
-		;;
-	--)
-		shift
-		break
-		;;
-	-*)
-		usage
-		;;
-	esac
-	shift
-done
-
-case "$#" in
-0)
-	git-rev-parse --symbolic --branches |
-	sort |
-	while read ref
-	do
-		if test "$headref" = "$ref"
-		then
-			pfx='*'
-		else
-			pfx=' '
-		fi
-		echo "$pfx $ref"
-	done
-	exit 0 ;;
-1)
-	head=HEAD ;;
-2)
-	head="$2^0" ;;
-esac
-branchname="$1"
-
-rev=$(git-rev-parse --verify "$head") || exit
-
-git-check-ref-format "heads/$branchname" ||
-	die "we do not like '$branchname' as a branch name."
-
-if [ -e "$GIT_DIR/refs/heads/$branchname" ]
-then
-	if test '' = "$force"
-	then
-		die "$branchname already exists."
-	elif test "$branchname" = "$headref"
-	then
-		die "cannot force-update the current branch."
-	fi
-fi
-if test "$create_log" = 'yes'
-then
-	mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$branchname")
-	touch "$GIT_DIR/logs/refs/heads/$branchname"
-fi
-git update-ref -m "branch: Created from $head" "refs/heads/$branchname" $rev
diff --git a/git.c b/git.c
index 930998b..5738cb4 100644
--- a/git.c
+++ b/git.c
@@ -226,6 +226,7 @@ static void handle_internal_command(int 
 	} commands[] = {
 		{ "add", cmd_add, RUN_SETUP },
 		{ "apply", cmd_apply },
+		{ "branch", cmd_branch, RUN_SETUP },
 		{ "cat-file", cmd_cat_file, RUN_SETUP },
 		{ "checkout-index", cmd_checkout_index, RUN_SETUP },
 		{ "check-ref-format", cmd_check_ref_format },