Merge refs/heads/master from .

11 files changed, 587 insertions, 178 deletions

diff --git a/Documentation/git-show-branch.txt b/Documentation/git-show-branch.txt
new file mode 100644
index 0000000000..71d5ba8fd7
--- /dev/null
+++ b/Documentation/git-show-branch.txt
@@ -0,0 +1,107 @@
+git-show-branch(1)
+==================
+v0.99.4, Aug 2005
+
+NAME
+----
+git-show-branch - Show branches and their commits.
+
+SYNOPSIS
+--------
+'git show-branch [--all] [--heads] [--tags] [--more=<n>] [--merge-base] <reference>...'
+
+DESCRIPTION
+-----------
+Shows the head commits from the named <reference> (or all refs under
+$GIT_DIR/refs/heads), and displays concise list of commit logs
+to show their relationship semi-visually.
+
+OPTIONS
+-------
+<reference>::
+	Name of the reference under $GIT_DIR/refs/.
+
+--all --heads --tags::
+	Show all refs under $GIT_DIR/refs, $GIT_DIR/refs/heads,
+	and $GIT_DIR/refs/tags, respectively.
+
+--more=<n>::
+	Usually the command stops output upon showing the commit
+	that is the common ancestor of all the branches.  This
+	flag tells the command to go <n> commits beyond that.
+
+--merge-base::
+	Instead of showing the commit list, just act like the
+	'git-merge-base' command except that it can accept more
+	than two heads.
+
+
+OUTPUT
+------
+Given N <references>, the first N lines are the one-line
+description from their commit message.  The branch head that is
+pointed at by $GIT_DIR/HEAD is prefixed with an asterisk '*'
+character while other heads are prefixed with a '!' character.
+
+Following these N lines, one-line log for each commit is
+displayed, indented N places.  If a commit is on the I-th
+branch, the I-th indentation character shows a '+' sign;
+otherwise it shows a space.  Each commit shows a short name that
+can be used as an exended SHA1 to name that commit.
+
+The following example shows three branches, "master", "fixes"
+and "mhf":
+
+------------------------------------------------
+$ git show-branch master fixes mhf
+! [master] Add 'git show-branch'.
+ ! [fixes] Introduce "reset type" flag to "git reset"
+  ! [mhf] Allow "+remote:local" refspec to cause --force when fetching.
+---
+  + [mhf] Allow "+remote:local" refspec to cause --force when fetching.
+  + [mhf~1] Use git-octopus when pulling more than one heads.
+ +  [fixes] Introduce "reset type" flag to "git reset"
+  + [mhf~2] "git fetch --force".
+  + [mhf~3] Use .git/remote/origin, not .git/branches/origin.
+  + [mhf~4] Make "git pull" and "git fetch" default to origin
+  + [mhf~5] Infamous 'octopus merge'
+  + [mhf~6] Retire git-parse-remote.
+  + [mhf~7] Multi-head fetch.
+  + [mhf~8] Start adding the $GIT_DIR/remotes/ support.
++++ [master] Add 'git show-branch'.
+------------------------------------------------
+
+These three branches all forked from a common commit, [master],
+whose commit message is "Add 'git show-branch'.  "fixes" branch
+adds one commit 'Introduce "reset type"'.  "mhf" branch has many
+other commits.
+
+When only one head is given, the output format changes slightly
+to conserve space.  The '+' sign to show which commit is
+reachable from which head and the first N lines to show the list
+of heads being displayed are both meaningless so they are
+omitted.  Also the label given to each commit does not repeat
+the name of the branch because it is obvious.
+
+------------------------------------------------
+$ git show-branch --more=4 master
+[master] Add 'git show-branch'.
+[~1] Add a new extended SHA1 syntax <name>~<num>
+[~2] Fix "git-diff-script A B"
+[~3] git-ls-files: generalized pathspecs
+[~4] Make "git-ls-files" work in subdirectories
+------------------------------------------------
+
+Author
+------
+Written by Junio C Hamano <junkio@cox.net>
+
+
+Documentation
+--------------
+Documentation by Junio C Hamano.
+
+
+GIT
+---
+Part of the link:git.html[git] suite
diff --git a/Documentation/git-show-branches-script.txt b/Documentation/git-show-branches-script.txt
deleted file mode 100644
index c7fb02cf7b..0000000000
--- a/Documentation/git-show-branches-script.txt
+++ /dev/null
@@ -1,71 +0,0 @@
-git-show-branches-script(1)
-===========================
-v0.99.4, Aug 2005
-
-NAME
-----
-git-show-branches-script - Show branches and their commits.
-
-SYNOPSIS
---------
-'git show-branches <reference>...'
-
-DESCRIPTION
------------
-Shows the head commits from the named <reference> (or all refs under
-$GIT_DIR/refs/heads), and displays concise list of commit logs
-to show their relationship semi-visually.
-
-OPTIONS
--------
-<reference>::
-	Name of the reference under $GIT_DIR/refs/heads/.
-
-
-OUTPUT
-------
-Given N <references>, the first N lines are the one-line
-description from their commit message.  The branch head that is
-pointed at by $GIT_DIR/HEAD is prefixed with an asterisk '*'
-character while other heads are prefixed with a '!' character.
-
-Following these N lines, one-line log for each commit is
-displayed, indented N places.  If a commit is on the I-th
-branch, the I-th indentation character shows a '+' sign;
-otherwise it shows a space.
-
-The following example shows three branches, "pu", "master" and
-"rc":
-
-------------------------------------------------
-* [pu] Add cheap local clone '-s' flag to git-clone-script
- ! [master] Documentation updates.
-  ! [rc] Merge master into rc
-+   Add cheap local clone '-s' flag to git-clone-script
-+   Alternate object pool mechanism updates.
-+   Audit rev-parse users.
-++  Documentation updates.
-  + Merge master into rc
-+++ [PATCH] plug memory leak in diff.c::diff_free_filepair()
-------------------------------------------------
-
-These three branches all forked from a common commit, "[PATCH]
-plug memory leak...", and "rc" has one commit ahead of it.  The
-"master" branch has one different commit that is also shared by
-"pu" branch, and "pu" branch has three more commits on top of
-"master" branch.
-
-
-Author
-------
-Written by Junio C Hamano <junkio@cox.net>
-
-
-Documentation
---------------
-Documentation by Junio C Hamano.
-
-
-GIT
----
-Part of the link:git.html[git] suite
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 8d313cba6e..9d4fccdd47 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -208,7 +208,7 @@ link:git-pull-script.html[git-pull-script]::
 link:git-commit-script.html[git-commit-script]::
 	Record changes to the repository.
 
-link:git-show-branches-script.html[git-show-branches-script]::
+link:git-show-branch.html[git-show-branch]::
 	Show branches and their commits.
 
 link:git-repack-script.html[git-repack-script]::
diff --git a/Makefile b/Makefile
index c0a84298b5..797c27fb04 100644
--- a/Makefile
+++ b/Makefile
@@ -71,7 +71,6 @@ SCRIPTS=git git-apply-patch-script git-merge-one-file-script git-prune-script \
 SCRIPTS += git-count-objects-script
 # SCRIPTS += git-send-email-script
 SCRIPTS += git-revert-script
-SCRIPTS += git-show-branches-script
 
 PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-read-tree git-commit-tree git-cat-file git-fsck-cache \
@@ -84,7 +83,7 @@ PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-diff-stages git-rev-parse git-patch-id git-pack-objects \
 	git-unpack-objects git-verify-pack git-receive-pack git-send-pack \
 	git-prune-packed git-fetch-pack git-upload-pack git-clone-pack \
-	git-show-index git-daemon git-var git-peek-remote \
+	git-show-index git-daemon git-var git-peek-remote git-show-branch \
 	git-update-server-info git-show-rev-cache git-build-rev-cache
 
 ifndef NO_CURL
diff --git a/commit.c b/commit.c
index 59e93d4590..e51eda1524 100644
--- a/commit.c
+++ b/commit.c
@@ -38,23 +38,32 @@ enum cmit_fmt get_commit_format(const char *arg)
 	die("invalid --pretty format");
 }
 
-static struct commit *check_commit(struct object *obj, const unsigned char *sha1)
+static struct commit *check_commit(struct object *obj,
+				   const unsigned char *sha1,
+				   int quiet)
 {
 	if (obj->type != commit_type) {
-		error("Object %s is a %s, not a commit", 
-		      sha1_to_hex(sha1), obj->type);
+		if (!quiet)
+			error("Object %s is a %s, not a commit",
+			      sha1_to_hex(sha1), obj->type);
 		return NULL;
 	}
 	return (struct commit *) obj;
 }
 
-struct commit *lookup_commit_reference(const unsigned char *sha1)
+struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
+					      int quiet)
 {
 	struct object *obj = deref_tag(parse_object(sha1));
 
 	if (!obj)
 		return NULL;
-	return check_commit(obj, sha1);
+	return check_commit(obj, sha1, quiet);
+}
+
+struct commit *lookup_commit_reference(const unsigned char *sha1)
+{
+	return lookup_commit_reference_gently(sha1, 0);
 }
 
 struct commit *lookup_commit(const unsigned char *sha1)
@@ -69,7 +78,7 @@ struct commit *lookup_commit(const unsigned char *sha1)
 	}
 	if (!obj->type)
 		obj->type = commit_type;
-	return check_commit(obj, sha1);
+	return check_commit(obj, sha1, 0);
 }
 
 static unsigned long parse_commit_date(const char *buf)
diff --git a/commit.h b/commit.h
index 5d179d4dc8..9dda2f045f 100644
--- a/commit.h
+++ b/commit.h
@@ -21,6 +21,8 @@ extern const char *commit_type;
 
 struct commit *lookup_commit(const unsigned char *sha1);
 struct commit *lookup_commit_reference(const unsigned char *sha1);
+struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
+					      int quiet);
 
 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size);
 
diff --git a/git-diff-script b/git-diff-script
index 926f594be4..99ff2640f1 100755
--- a/git-diff-script
+++ b/git-diff-script
@@ -8,8 +8,14 @@ case "${#rev[*]}" in
 1)
 	git-diff-cache -M -p "$@";;
 2)
-	begin=$(echo "${rev[1]}" | tr -d '^')
-	end="${rev[0]}"
+	case "${rev[1]}" in
+	^?*)
+		begin=$(echo "${rev[1]}" | tr -d '^')
+		end="${rev[0]}" ;;
+	*)
+		begin="${rev[0]}"
+		end="${rev[1]}"	;;
+	esac
 	git-diff-tree -M -p $flags $begin $end $files;;
 *)
 	echo "I don't understand"
diff --git a/git-show-branches-script b/git-show-branches-script
deleted file mode 100755
index 90018a9e88..0000000000
--- a/git-show-branches-script
+++ /dev/null
@@ -1,61 +0,0 @@
-#!/bin/sh
-#
-# Show refs and their recent commits.
-#
-
-. git-sh-setup-script || die "Not a git repository"
-
-usage () {
-    die "usage: $0 <ref>..."
-}
-
-headref=`readlink $GIT_DIR/HEAD`
-
-case "$(git-rev-parse --no-revs)" in '') ;; *) usage ;; esac
-revs=$(git-rev-parse --revs-only --symbolic --no-flags "$@")
-flags=$(git-rev-parse --revs-only --flags "$@")
-case "$revs" in
-'')
-	revs=$(git-rev-parse --symbolic --all | sed -ne 's|^refs/heads/||p' |
-	       sort)
-	shift ;;
-esac
-set x $revs
-shift
-
-hh= in=
-for ref
-do
-	case "/$headref" in
-	*/"$ref") H='*' ;;
-	*) H='!' ;;
-	esac
-	h=`git-rev-parse --verify "$ref^0" 2>/dev/null` || continue
-	l=`git-log-script --max-count=1 --pretty=oneline "$h" |
-		sed -e 's/^[^ ]* //'`
-	hh="$hh $h"
-	echo "$in$H [$ref] $l"
-	in="$in "
-done
-set x $hh
-shift
-
-git-rev-list --pretty=oneline $flags $@ |
-while read v l
-do
-	in=''
-	for h
-	do
-		b=`git-merge-base $h $v`
-		case "$b" in
-		$v) in="$in+" ;;
-		*)  in="$in " ;;
-		esac
-	done
-
-	echo "$in $l"
-	case "$in" in
-	*' '*) ;;
-	*) break ;;
-	esac
-done
diff --git a/ls-files.c b/ls-files.c
index c76e30e990..2c7aada88c 100644
--- a/ls-files.c
+++ b/ls-files.c
@@ -21,7 +21,7 @@ static int line_terminator = '\n';
 
 static int prefix_len = 0, prefix_offset = 0;
 static const char *prefix = NULL;
-static const char *glob = NULL;
+static const char **pathspec = NULL;
 
 static const char *tag_cached = "";
 static const char *tag_unmerged = "";
@@ -302,6 +302,33 @@ static int cmp_name(const void *p1, const void *p2)
 				  e2->name, e2->len);
 }
 
+/*
+ * Match a pathspec against a filename. The first "len" characters
+ * are the common prefix
+ */
+static int match(const char **spec, const char *filename, int len)
+{
+	const char *m;
+
+	while ((m = *spec++) != NULL) {
+		int matchlen = strlen(m + len);
+
+		if (!matchlen)
+			return 1;
+		if (!strncmp(m + len, filename + len, matchlen)) {
+			if (m[len + matchlen - 1] == '/')
+				return 1;
+			switch (filename[len + matchlen]) {
+			case '/': case '\0':
+				return 1;
+			}
+		}
+		if (!fnmatch(m + len, filename + len, 0))
+			return 1;
+	}
+	return 0;
+}
+
 static void show_dir_entry(const char *tag, struct nond_on_fs *ent)
 {
 	int len = prefix_len;
@@ -310,7 +337,7 @@ static void show_dir_entry(const char *tag, struct nond_on_fs *ent)
 	if (len >= ent->len)
 		die("git-ls-files: internal error - directory entry not superset of prefix");
 
-	if (glob && fnmatch(glob, ent->name + len, 0))
+	if (pathspec && !match(pathspec, ent->name, len))
 		return;
 
 	printf("%s%s%c", tag, ent->name + offset, line_terminator);
@@ -373,7 +400,7 @@ static void show_ce_entry(const char *tag, struct cache_entry *ce)
 	if (len >= ce_namelen(ce))
 		die("git-ls-files: internal error - cache entry not superset of prefix");
 
-	if (glob && fnmatch(glob, ce->name + len, 0))
+	if (pathspec && !match(pathspec, ce->name, len))
 		return;
 
 	if (!show_stage)
@@ -455,36 +482,44 @@ static void prune_cache(void)
 	active_nr = last;
 }
 
-/*
- * If the glob starts with a subdirectory, append it to
- * the prefix instead, for more efficient operation.
- *
- * But we do not update the "prefix_offset", which tells
- * how much of the name to ignore at printout.
- */
-static void extend_prefix(void)
+static void verify_pathspec(void)
 {
-	const char *p, *slash;
-	char c;
-
-	p = glob;
-	slash = NULL;
-	while ((c = *p++) != '\0') {
-		if (c == '*')
-			break;
-		if (c == '/')
-			slash = p;
+	const char **p, *n, *prev;
+	char *real_prefix;
+	unsigned long max;
+
+	prev = NULL;
+	max = PATH_MAX;
+	for (p = pathspec; (n = *p) != NULL; p++) {
+		int i, len = 0;
+		for (i = 0; i < max; i++) {
+			char c = n[i];
+			if (prev && prev[i] != c)
+				break;
+			if (c == '*' || c == '?')
+				break;
+			if (c == '/')
+				len = i+1;
+		}
+		prev = n;
+		if (len < max) {
+			max = len;
+			if (!max)
+				break;
+		}
 	}
-	if (slash) {
-		int len = slash - glob;
-		char *newprefix = xmalloc(len + prefix_len + 1);
-		memcpy(newprefix, prefix, prefix_len);
-		memcpy(newprefix + prefix_len, glob, len);
-		prefix_len += len;
-		newprefix[prefix_len] = 0;
-		prefix = newprefix;
-		glob = *slash ? slash : NULL;
+
+	if (prefix_offset > max || memcmp(prev, prefix, prefix_offset))
+		die("git-ls-files: cannot generate relative filenames containing '..'");
+
+	real_prefix = NULL;
+	prefix_len = max;
+	if (max) {
+		real_prefix = xmalloc(max + 1);
+		memcpy(real_prefix, prev, max);
+		real_prefix[max] = 0;
 	}
+	prefix = real_prefix;
 }
 
 static const char ls_files_usage[] =
@@ -499,7 +534,7 @@ int main(int argc, char **argv)
 
 	prefix = setup_git_directory();
 	if (prefix)
-		prefix_offset = prefix_len = strlen(prefix);
+		prefix_offset = strlen(prefix);
 
 	for (i = 1; i < argc; i++) {
 		char *arg = argv[i];
@@ -577,13 +612,16 @@ int main(int argc, char **argv)
 			prefix_offset = 0;
 			continue;
 		}
-		if (glob || *arg == '-')
+		if (*arg == '-')
 			usage(ls_files_usage);
-		glob = arg;
+		break;
 	}
 
-	if (glob)
-		extend_prefix();
+	pathspec = get_pathspec(prefix, argv + i);
+
+	/* Verify that the pathspec matches the prefix */
+	if (pathspec)
+		verify_pathspec();
 
 	if (show_ignored && !exc_given) {
 		fprintf(stderr, "%s: --ignored needs some exclude pattern\n",
diff --git a/sha1_name.c b/sha1_name.c
index 6744bbbef5..133af3b6c1 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -191,9 +191,29 @@ static int get_parent(const char *name, int len,
 	return -1;
 }
 
+static int get_nth_ancestor(const char *name, int len,
+			    unsigned char *result, int generation)
+{
+	unsigned char sha1[20];
+	int ret = get_sha1_1(name, len, sha1);
+	if (ret)
+		return ret;
+
+	while (generation--) {
+		struct commit *commit = lookup_commit_reference(sha1);
+
+		if (!commit || parse_commit(commit) || !commit->parents)
+			return -1;
+		memcpy(sha1, commit->parents->item->object.sha1, 20);
+	}
+	memcpy(result, sha1, 20);
+	return 0;
+}
+
 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 {
 	int parent, ret;
+	const char *cp;
 
 	/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 	if (len > 2 && name[len-2] == '^' &&
@@ -210,6 +230,27 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 	if (parent >= 0)
 		return get_parent(name, len, sha1, parent);
 
+	/* "name~3" is "name^^^",
+	 * "name~12" is "name^^^^^^^^^^^^", and
+	 * "name~" and "name~0" are name -- not "name^0"!
+	 */
+	parent = 0;
+	for (cp = name + len - 1; name <= cp; cp--) {
+		int ch = *cp;
+		if ('0' <= ch && ch <= '9')
+			continue;
+		if (ch != '~')
+			parent = -1;
+		break;
+	}
+	if (!parent && *cp == '~') {
+		int len1 = cp - name;
+		cp++;
+		while (cp < name + len)
+			parent = parent * 10 + *cp++ - '0';
+		return get_nth_ancestor(name, len1, sha1, parent);
+	}
+
 	ret = get_sha1_basic(name, len, sha1);
 	if (!ret)
 		return 0;
diff --git a/show-branch.c b/show-branch.c
new file mode 100644
index 0000000000..fc827ee497
--- /dev/null
+++ b/show-branch.c
@@ -0,0 +1,339 @@
+#include <stdlib.h>
+#include "cache.h"
+#include "commit.h"
+#include "refs.h"
+
+static const char show_branch_usage[] =
+"git-show-branch [--all] [--heads] [--tags] [--more=count] [<refs>...]";
+
+#define UNINTERESTING	01
+
+#define REV_SHIFT	 2
+#define MAX_REVS	29 /* should not exceed bits_per_int - REV_SHIFT */
+
+static struct commit *interesting(struct commit_list *list)
+{
+	while (list) {
+		struct commit *commit = list->item;
+		list = list->next;
+		if (commit->object.flags & UNINTERESTING)
+			continue;
+		return commit;
+	}
+	return NULL;
+}
+
+static struct commit *pop_one_commit(struct commit_list **list_p)
+{
+	struct commit *commit;
+	struct commit_list *list;
+	list = *list_p;
+	commit = list->item;
+	*list_p = list->next;
+	free(list);
+	return commit;
+}
+
+struct commit_name {
+	int head_rev;	/* which head's ancestor? */
+	int generation;	/* how many parents away from head_rev */
+};
+
+/* Name the commit as nth generation ancestor of head_rev;
+ * we count only the first-parent relationship for naming purposes.
+ */
+static void name_commit(struct commit *commit, int head_rev, int nth)
+{
+	struct commit_name *name;
+	if (!commit->object.util)
+		commit->object.util = xmalloc(sizeof(struct commit_name));
+	name = commit->object.util;
+	name->head_rev = head_rev;
+	name->generation = nth;
+}
+
+/* Parent is the first parent of the commit.  We may name it
+ * as (n+1)th generation ancestor of the same head_rev as
+ * commit is nth generation ancestore of, if that generation
+ * number is better than the name it already has.
+ */
+static void name_parent(struct commit *commit, struct commit *parent)
+{
+	struct commit_name *commit_name = commit->object.util;
+	struct commit_name *parent_name = parent->object.util;
+	if (!commit_name)
+		return;
+	if (!parent_name ||
+	    commit_name->generation + 1 < parent_name->generation)
+		name_commit(parent, commit_name->head_rev,
+			    commit_name->generation + 1);
+}
+
+static int mark_seen(struct commit *commit, struct commit_list **seen_p)
+{
+	if (!commit->object.flags) {
+		insert_by_date(commit, seen_p);
+		return 1;
+	}
+	return 0;
+}
+
+static void join_revs(struct commit_list **list_p,
+		      struct commit_list **seen_p,
+		      int num_rev, int extra)
+{
+	int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
+	int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
+
+	while (*list_p) {
+		struct commit_list *parents;
+		struct commit *commit = pop_one_commit(list_p);
+		int flags = commit->object.flags & all_mask;
+		int nth_parent = 0;
+		int still_interesting = !!interesting(*list_p);
+
+		if (!still_interesting && extra < 0)
+			break;
+
+		mark_seen(commit, seen_p);
+		if ((flags & all_revs) == all_revs)
+			flags |= UNINTERESTING;
+		parents = commit->parents;
+
+		while (parents) {
+			struct commit *p = parents->item;
+			int this_flag = p->object.flags;
+			parents = parents->next;
+			nth_parent++;
+			if (nth_parent == 1)
+				name_parent(commit, p);
+
+			if ((this_flag & flags) == flags)
+				continue;
+			parse_commit(p);
+			if (mark_seen(p, seen_p) && !still_interesting)
+				extra--;
+			p->object.flags |= flags;
+			insert_by_date(p, list_p);
+		}
+	}
+}
+
+static void show_one_commit(struct commit *commit, char **head_name)
+{
+	char pretty[128], *cp;
+	struct commit_name *name = commit->object.util;
+	pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
+			    pretty, sizeof(pretty));
+	if (!strncmp(pretty, "[PATCH] ", 8))
+		cp = pretty + 8;
+	else
+		cp = pretty;
+	if (name && head_name) {
+		printf("[%s", head_name[name->head_rev]);
+		if (name->generation)
+			printf("~%d", name->generation);
+		printf("] ");
+	}
+	puts(cp);
+}
+
+static char *ref_name[MAX_REVS + 1];
+static int ref_name_cnt;
+
+static int append_ref(const char *refname, const unsigned char *sha1)
+{
+	struct commit *commit = lookup_commit_reference_gently(sha1, 1);
+	if (!commit)
+		return 0;
+	if (MAX_REVS < ref_name_cnt) {
+		fprintf(stderr, "warning: ignoring %s; "
+			"cannot handle more than %d refs",
+			refname, MAX_REVS);
+		return 0;
+	}
+	ref_name[ref_name_cnt++] = strdup(refname);
+	ref_name[ref_name_cnt] = NULL;
+	return 0;
+}
+
+static int append_head_ref(const char *refname, const unsigned char *sha1)
+{
+	if (strncmp(refname, "refs/heads/", 11))
+		return 0;
+	return append_ref(refname + 5, sha1);
+}
+
+static int append_tag_ref(const char *refname, const unsigned char *sha1)
+{
+	if (strncmp(refname, "refs/tags/", 10))
+		return 0;
+	return append_ref(refname + 5, sha1);
+}
+
+static void snarf_refs(int head, int tag)
+{
+	if (head)
+		for_each_ref(append_head_ref);
+	if (tag)
+		for_each_ref(append_tag_ref);
+}
+
+static int rev_is_head(char *head_path, int headlen,
+		       char *name,
+		       unsigned char *head_sha1, unsigned char *sha1)
+{
+	int namelen;
+	if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
+		return 0;
+	namelen = strlen(name);
+	if ((headlen < namelen) ||
+	    memcmp(head_path + headlen - namelen, name, namelen))
+		return 0;
+	if (headlen == namelen ||
+	    head_path[headlen - namelen - 1] == '/')
+		return 1;
+	return 0;
+}
+
+static int show_merge_base(struct commit_list *seen, int num_rev)
+{
+	int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
+	int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
+
+	while (seen) {
+		struct commit *commit = pop_one_commit(&seen);
+		int flags = commit->object.flags & all_mask;
+		if (!(flags & UNINTERESTING) &&
+		    ((flags & all_revs) == all_revs)) {
+			puts(sha1_to_hex(commit->object.sha1));
+			return 0;
+		}
+	}
+	return 1;
+}
+
+int main(int ac, char **av)
+{
+	struct commit *rev[MAX_REVS], *commit;
+	struct commit_list *list = NULL, *seen = NULL;
+	int num_rev, i, extra = 0;
+	int all_heads = 0, all_tags = 0;
+	char head_path[128];
+	int head_path_len;
+	unsigned char head_sha1[20];
+	int merge_base = 0;
+	char **label;
+
+	while (1 < ac && av[1][0] == '-') {
+		char *arg = av[1];
+		if (!strcmp(arg, "--all"))
+			all_heads = all_tags = 1;
+		else if (!strcmp(arg, "--heads"))
+			all_heads = 1;
+		else if (!strcmp(arg, "--tags"))
+			all_tags = 1;
+		else if (!strcmp(arg, "--more"))
+			extra = 1;
+		else if (!strncmp(arg, "--more=", 7)) {
+			extra = atoi(arg + 7);
+			if (extra < 0)
+				usage(show_branch_usage);
+		}
+		else if (!strcmp(arg, "--merge-base"))
+			merge_base = 1;
+		else
+			usage(show_branch_usage);
+		ac--; av++;
+	}
+	ac--; av++;
+
+	if (all_heads + all_tags)
+		snarf_refs(all_heads, all_tags);
+
+	while (0 < ac) {
+		unsigned char revkey[20];
+		if (get_sha1(*av, revkey))
+			die("bad sha1 reference %s", *av);
+		append_ref(*av, revkey);
+		ac--; av++;
+	}
+
+	/* If still no revs, then add heads */
+	if (!ref_name_cnt)
+		snarf_refs(1, 0);
+
+	for (num_rev = 0; ref_name[num_rev]; num_rev++) {
+		unsigned char revkey[20];
+
+		if (MAX_REVS <= num_rev)
+			die("cannot handle more than %d revs.", MAX_REVS);
+		if (get_sha1(ref_name[num_rev], revkey))
+			usage(show_branch_usage);
+		commit = lookup_commit_reference(revkey);
+		if (!commit)
+			die("cannot find commit %s (%s)",
+			    ref_name[num_rev], revkey);
+		parse_commit(commit);
+		if (!commit->object.util)
+			name_commit(commit, num_rev, 0);
+		mark_seen(commit, &seen);
+
+		/* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
+		 * and so on.  REV_SHIFT bits from bit 0 are used for
+		 * internal bookkeeping.
+		 */
+		commit->object.flags |= 1u << (num_rev + REV_SHIFT);
+		insert_by_date(commit, &list);
+		rev[num_rev] = commit;
+	}
+	join_revs(&list, &seen, num_rev, extra);
+
+	head_path_len = readlink(".git/HEAD", head_path, sizeof(head_path)-1);
+	if ((head_path_len < 0) || get_sha1("HEAD", head_sha1))
+		head_path[0] = 0;
+	else
+		head_path[head_path_len] = 0;
+
+	if (merge_base)
+		return show_merge_base(seen, num_rev);
+
+	/* Show list */
+	if (1 < num_rev) {
+		for (i = 0; i < num_rev; i++) {
+			int j;
+			int is_head = rev_is_head(head_path,
+						  head_path_len,
+						  ref_name[i],
+						  head_sha1,
+						  rev[i]->object.sha1);
+			for (j = 0; j < i; j++)
+				putchar(' ');
+			printf("%c [%s] ", is_head ? '*' : '!', ref_name[i]);
+			show_one_commit(rev[i], NULL);
+		}
+		for (i = 0; i < num_rev; i++)
+			putchar('-');
+		putchar('\n');
+	}
+
+	label = ref_name;
+	while (seen) {
+		struct commit *commit = pop_one_commit(&seen);
+		int this_flag = commit->object.flags;
+		static char *obvious[] = { "" };
+
+		if ((this_flag & UNINTERESTING) && (--extra < 0))
+			break;
+		if (1 < num_rev) {
+			for (i = 0; i < num_rev; i++)
+				putchar((this_flag & (1u << (i + REV_SHIFT)))
+					? '+' : ' ');
+			putchar(' ');
+		}
+		show_one_commit(commit, label);
+		if (num_rev == 1)
+			label = obvious;
+	}
+	return 0;
+}