[PATCH 0/9] add --ff option to cherry-pick

[PATCH 0/9] add --ff option to cherry-pick

[Christian Couder]

Changes since the previous series are the following:

- added some tests in a new patch
- added some documentation in a new patch
- added a patch to use the new "reset" function in builtin-merge.c
- made --ff incompatible with --edit -x and --signoff too, thanks to Paolo
- improved the first patch with suggestions from Stephen Boyd, thanks
- made a "struct lock_file" static to initialize it in the first patch
- improved commit messages

Christian Couder (8):
  reset: refactor updating heads into a static function
  reset: refactor reseting in its own function
  reset: make reset function non static and declare it in "reset.h"
  revert: add --ff option to allow fast forward when cherry-picking
  cherry-pick: add tests for new --ff option
  Documentation: describe new cherry-pick --ff option
  rebase -i: use new --ff cherry-pick option
  merge: use new "reset" function instead of running "git read-tree"

Stephan Beyer (1):
  revert: libify cherry-pick and revert functionnality

 Documentation/git-cherry-pick.txt |    6 +-
 Makefile                          |    2 +
 builtin-merge.c                   |   31 ++---
 builtin-reset.c                   |  175 ++++++++++++----------
 builtin-revert.c                  |  303 +++++++++----------------------------
 git-rebase--interactive.sh        |   15 +--
 pick.c                            |  218 ++++++++++++++++++++++++++
 pick.h                            |   13 ++
 reset.h                           |   10 ++
 t/t3506-cherry-pick-ff.sh         |   38 +++++
 10 files changed, 471 insertions(+), 340 deletions(-)
 create mode 100644 pick.c
 create mode 100644 pick.h
 create mode 100644 reset.h
 create mode 100755 t/t3506-cherry-pick-ff.sh

[PATCH 1/9] revert: libify cherry-pick and revert functionnality

[Christian Couder]

From: Stephan Beyer <s-beyer@gmx.net>

The goal of this commit is to abstract out "git cherry-pick" and
"git revert" functionnality into a new pick_commit() function made
of code from "builtin-revert.c".

The new pick_commit() function is in a new "pick.c" file with an
associated "pick.h".

This function starts from the current index (not HEAD), and allow
the effect of one commit replayed (either forward or backward) to
that state, leaving the result in the index. So it makes it
possible to replay many commits to the index in sequence without
commiting in between.

This commit is made of code from the sequencer GSoC project:

git://repo.or.cz/git/sbeyer.git

(at commit 5a78908b70ceb5a4ea9fd4b82f07ceba1f019079)

And it contains some changes and comments suggested by Junio.

The original commit in the sequencer project that introduced
this change is: 94a568a78d243d7a6c13778bc6b7ac1eb46e48cc

Mentored-by: Daniel Barkalow <barkalow@iabervon.org>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Makefile         |    2 +
 builtin-revert.c |  272 +++++++++---------------------------------------------
 pick.c           |  218 +++++++++++++++++++++++++++++++++++++++++++
 pick.h           |   13 +++
 4 files changed, 277 insertions(+), 228 deletions(-)
 create mode 100644 pick.c
 create mode 100644 pick.h

diff --git a/Makefile b/Makefile
index d624530..71901c8 100644
--- a/Makefile
+++ b/Makefile
@@ -458,6 +458,7 @@ LIB_H += pack-refs.h
 LIB_H += pack-revindex.h
 LIB_H += parse-options.h
 LIB_H += patch-ids.h
+LIB_H += pick.h
 LIB_H += pkt-line.h
 LIB_H += progress.h
 LIB_H += quote.h
@@ -550,6 +551,7 @@ LIB_OBJS += parse-options.o
 LIB_OBJS += patch-delta.o
 LIB_OBJS += patch-ids.o
 LIB_OBJS += path.o
+LIB_OBJS += pick.o
 LIB_OBJS += pkt-line.o
 LIB_OBJS += preload-index.o
 LIB_OBJS += pretty.o
diff --git a/builtin-revert.c b/builtin-revert.c
index 8ac86f0..7488d4c 100644
--- a/builtin-revert.c
+++ b/builtin-revert.c
@@ -1,18 +1,14 @@
 #include "cache.h"
 #include "builtin.h"
-#include "object.h"
 #include "commit.h"
 #include "tag.h"
-#include "wt-status.h"
-#include "run-command.h"
 #include "exec_cmd.h"
 #include "utf8.h"
 #include "parse-options.h"
-#include "cache-tree.h"
 #include "diff.h"
 #include "revision.h"
 #include "rerere.h"
-#include "merge-recursive.h"
+#include "pick.h"
 
 /*
  * This implements the builtins revert and cherry-pick.
@@ -35,26 +31,24 @@ static const char * const cherry_pick_usage[] = {
 	NULL
 };
 
-static int edit, no_replay, no_commit, mainline, signoff;
-static enum { REVERT, CHERRY_PICK } action;
+static int edit, no_commit, mainline, signoff;
+static int flags;
 static struct commit *commit;
 static int allow_rerere_auto;
 
-static const char *me;
-
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
 static void parse_args(int argc, const char **argv)
 {
 	const char * const * usage_str =
-		action == REVERT ?  revert_usage : cherry_pick_usage;
+		flags & PICK_REVERSE ? revert_usage : cherry_pick_usage;
 	unsigned char sha1[20];
 	const char *arg;
 	int noop;
 	struct option options[] = {
 		OPT_BOOLEAN('n', "no-commit", &no_commit, "don't automatically commit"),
 		OPT_BOOLEAN('e', "edit", &edit, "edit the commit message"),
-		OPT_BOOLEAN('x', NULL, &no_replay, "append commit name when cherry-picking"),
+		OPT_BIT('x', NULL, &flags, "append commit name when cherry-picking", PICK_ADD_NOTE),
 		OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
 		OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
 		OPT_INTEGER('m', "mainline", &mainline, "parent number"),
@@ -79,42 +73,12 @@ static void parse_args(int argc, const char **argv)
 		die ("'%s' does not point to a commit", arg);
 }
 
-static char *get_oneline(const char *message)
-{
-	char *result;
-	const char *p = message, *abbrev, *eol;
-	int abbrev_len, oneline_len;
-
-	if (!p)
-		die ("Could not read commit message of %s",
-				sha1_to_hex(commit->object.sha1));
-	while (*p && (*p != '\n' || p[1] != '\n'))
-		p++;
-
-	if (*p) {
-		p += 2;
-		for (eol = p + 1; *eol && *eol != '\n'; eol++)
-			; /* do nothing */
-	} else
-		eol = p;
-	abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
-	abbrev_len = strlen(abbrev);
-	oneline_len = eol - p;
-	result = xmalloc(abbrev_len + 5 + oneline_len);
-	memcpy(result, abbrev, abbrev_len);
-	memcpy(result + abbrev_len, "... ", 4);
-	memcpy(result + abbrev_len + 4, p, oneline_len);
-	result[abbrev_len + 4 + oneline_len] = '\0';
-	return result;
-}
-
 static char *get_encoding(const char *message)
 {
 	const char *p = message, *eol;
 
 	if (!p)
-		die ("Could not read commit message of %s",
-				sha1_to_hex(commit->object.sha1));
+		return NULL;
 	while (*p && *p != '\n') {
 		for (eol = p + 1; *eol && *eol != '\n'; eol++)
 			; /* do nothing */
@@ -130,30 +94,6 @@ static char *get_encoding(const char *message)
 	return NULL;
 }
 
-static struct lock_file msg_file;
-static int msg_fd;
-
-static void add_to_msg(const char *string)
-{
-	int len = strlen(string);
-	if (write_in_full(msg_fd, string, len) < 0)
-		die_errno ("Could not write to MERGE_MSG");
-}
-
-static void add_message_to_msg(const char *message)
-{
-	const char *p = message;
-	while (*p && (*p != '\n' || p[1] != '\n'))
-		p++;
-
-	if (!*p)
-		add_to_msg(sha1_to_hex(commit->object.sha1));
-
-	p += 2;
-	add_to_msg(p);
-	return;
-}
-
 static void set_author_ident_env(const char *message)
 {
 	const char *p = message;
@@ -216,7 +156,7 @@ static char *help_msg(const unsigned char *sha1)
 	       "mark the corrected paths with 'git add <paths>' "
 	       "or 'git rm <paths>' and commit the result.");
 
-	if (action == CHERRY_PICK) {
+	if (!(flags & PICK_REVERSE)) {
 		sprintf(helpbuf + strlen(helpbuf),
 			"\nWhen commiting, use the option "
 			"'-c %s' to retain authorship and message.",
@@ -225,14 +165,17 @@ static char *help_msg(const unsigned char *sha1)
 	return helpbuf;
 }
 
-static struct tree *empty_tree(void)
+static void write_message(struct strbuf *msgbuf, const char *filename)
 {
-	struct tree *tree = xcalloc(1, sizeof(struct tree));
-
-	tree->object.parsed = 1;
-	tree->object.type = OBJ_TREE;
-	pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
-	return tree;
+	static struct lock_file msg_file;
+	int msg_fd;
+	msg_fd = hold_lock_file_for_update(&msg_file, filename,
+					   LOCK_DIE_ON_ERROR);
+	if (write_in_full(msg_fd, msgbuf->buf, msgbuf->len) < 0)
+		die_errno("Could not write to %s.", filename);
+	strbuf_release(msgbuf);
+	if (commit_lock_file(&msg_file) < 0)
+		die("Error wrapping up %s", filename);
 }
 
 static NORETURN void die_dirty_index(const char *me)
@@ -250,175 +193,53 @@ static NORETURN void die_dirty_index(const char *me)
 
 static int revert_or_cherry_pick(int argc, const char **argv)
 {
-	unsigned char head[20];
-	struct commit *base, *next, *parent;
-	int i, index_fd, clean;
-	char *oneline, *reencoded_message = NULL;
-	const char *message, *encoding;
-	char *defmsg = git_pathdup("MERGE_MSG");
-	struct merge_options o;
-	struct tree *result, *next_tree, *base_tree, *head_tree;
-	static struct lock_file index_lock;
+	const char *me;
+	struct strbuf msgbuf;
+	char *reencoded_message = NULL;
+	const char *encoding;
+	int failed;
 
 	git_config(git_default_config, NULL);
-	me = action == REVERT ? "revert" : "cherry-pick";
+	me = flags & PICK_REVERSE ? "revert" : "cherry-pick";
 	setenv(GIT_REFLOG_ACTION, me, 0);
 	parse_args(argc, argv);
 
-	/* this is copied from the shell script, but it's never triggered... */
-	if (action == REVERT && !no_replay)
-		die("revert is incompatible with replay");
-
 	if (read_cache() < 0)
 		die("git %s: failed to read the index", me);
-	if (no_commit) {
-		/*
-		 * We do not intend to commit immediately.  We just want to
-		 * merge the differences in, so let's compute the tree
-		 * that represents the "current" state for merge-recursive
-		 * to work on.
-		 */
-		if (write_cache_as_tree(head, 0, NULL))
-			die ("Your index file is unmerged.");
-	} else {
-		if (get_sha1("HEAD", head))
-			die ("You do not have a valid HEAD");
-		if (index_differs_from("HEAD", 0))
-			die_dirty_index(me);
-	}
-	discard_cache();
-
-	index_fd = hold_locked_index(&index_lock, 1);
+	if (!no_commit && index_differs_from("HEAD", 0))
+		die_dirty_index(me);
 
-	if (!commit->parents) {
-		if (action == REVERT)
-			die ("Cannot revert a root commit");
-		parent = NULL;
-	}
-	else if (commit->parents->next) {
-		/* Reverting or cherry-picking a merge commit */
-		int cnt;
-		struct commit_list *p;
-
-		if (!mainline)
-			die("Commit %s is a merge but no -m option was given.",
-			    sha1_to_hex(commit->object.sha1));
-
-		for (cnt = 1, p = commit->parents;
-		     cnt != mainline && p;
-		     cnt++)
-			p = p->next;
-		if (cnt != mainline || !p)
-			die("Commit %s does not have parent %d",
-			    sha1_to_hex(commit->object.sha1), mainline);
-		parent = p->item;
-	} else if (0 < mainline)
-		die("Mainline was specified but commit %s is not a merge.",
-		    sha1_to_hex(commit->object.sha1));
-	else
-		parent = commit->parents->item;
-
-	if (!(message = commit->buffer))
-		die ("Cannot get commit message for %s",
+	if (!commit->buffer)
+		return error("Cannot get commit message for %s",
 				sha1_to_hex(commit->object.sha1));
-
-	if (parent && parse_commit(parent) < 0)
-		die("%s: cannot parse parent commit %s",
-		    me, sha1_to_hex(parent->object.sha1));
-
-	/*
-	 * "commit" is an existing commit.  We would want to apply
-	 * the difference it introduces since its first parent "prev"
-	 * on top of the current HEAD if we are cherry-pick.  Or the
-	 * reverse of it if we are revert.
-	 */
-
-	msg_fd = hold_lock_file_for_update(&msg_file, defmsg,
-					   LOCK_DIE_ON_ERROR);
-
-	encoding = get_encoding(message);
+	encoding = get_encoding(commit->buffer);
 	if (!encoding)
 		encoding = "UTF-8";
 	if (!git_commit_encoding)
 		git_commit_encoding = "UTF-8";
-	if ((reencoded_message = reencode_string(message,
+	if ((reencoded_message = reencode_string(commit->buffer,
 					git_commit_encoding, encoding)))
-		message = reencoded_message;
-
-	oneline = get_oneline(message);
-
-	if (action == REVERT) {
-		char *oneline_body = strchr(oneline, ' ');
-
-		base = commit;
-		next = parent;
-		add_to_msg("Revert \"");
-		add_to_msg(oneline_body + 1);
-		add_to_msg("\"\n\nThis reverts commit ");
-		add_to_msg(sha1_to_hex(commit->object.sha1));
-
-		if (commit->parents->next) {
-			add_to_msg(", reversing\nchanges made to ");
-			add_to_msg(sha1_to_hex(parent->object.sha1));
-		}
-		add_to_msg(".\n");
-	} else {
-		base = parent;
-		next = commit;
-		set_author_ident_env(message);
-		add_message_to_msg(message);
-		if (no_replay) {
-			add_to_msg("(cherry picked from commit ");
-			add_to_msg(sha1_to_hex(commit->object.sha1));
-			add_to_msg(")\n");
-		}
-	}
-
-	read_cache();
-	init_merge_options(&o);
-	o.branch1 = "HEAD";
-	o.branch2 = oneline;
+		commit->buffer = reencoded_message;
 
-	head_tree = parse_tree_indirect(head);
-	next_tree = next ? next->tree : empty_tree();
-	base_tree = base ? base->tree : empty_tree();
-
-	clean = merge_trees(&o,
-			    head_tree,
-			    next_tree, base_tree, &result);
-
-	if (active_cache_changed &&
-	    (write_cache(index_fd, active_cache, active_nr) ||
-	     commit_locked_index(&index_lock)))
-		die("%s: Unable to write new index file", me);
-	rollback_lock_file(&index_lock);
-
-	if (!clean) {
-		add_to_msg("\nConflicts:\n\n");
-		for (i = 0; i < active_nr;) {
-			struct cache_entry *ce = active_cache[i++];
-			if (ce_stage(ce)) {
-				add_to_msg("\t");
-				add_to_msg(ce->name);
-				add_to_msg("\n");
-				while (i < active_nr && !strcmp(ce->name,
-						active_cache[i]->name))
-					i++;
-			}
-		}
-		if (commit_lock_file(&msg_file) < 0)
-			die ("Error wrapping up %s", defmsg);
+	failed = pick_commit(commit, mainline, flags, &msgbuf);
+	if (failed < 0) {
+		exit(1);
+	} else if (failed > 0) {
 		fprintf(stderr, "Automatic %s failed.%s\n",
 			me, help_msg(commit->object.sha1));
+		write_message(&msgbuf, git_path("MERGE_MSG"));
 		rerere(allow_rerere_auto);
 		exit(1);
 	}
-	if (commit_lock_file(&msg_file) < 0)
-		die ("Error wrapping up %s", defmsg);
+	if (!(flags & PICK_REVERSE))
+		set_author_ident_env(commit->buffer);
+	free(reencoded_message);
+
 	fprintf(stderr, "Finished one %s.\n", me);
 
+	write_message(&msgbuf, git_path("MERGE_MSG"));
+
 	/*
-	 *
 	 * If we are cherry-pick, and if the merge did not result in
 	 * hand-editing, we will hit this commit and inherit the original
 	 * author date and name.
@@ -436,14 +257,11 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 			args[i++] = "-s";
 		if (!edit) {
 			args[i++] = "-F";
-			args[i++] = defmsg;
+			args[i++] = git_path("MERGE_MSG");
 		}
 		args[i] = NULL;
 		return execv_git_cmd(args);
 	}
-	free(reencoded_message);
-	free(defmsg);
-
 	return 0;
 }
 
@@ -451,14 +269,12 @@ int cmd_revert(int argc, const char **argv, const char *prefix)
 {
 	if (isatty(0))
 		edit = 1;
-	no_replay = 1;
-	action = REVERT;
+	flags = PICK_REVERSE | PICK_ADD_NOTE;
 	return revert_or_cherry_pick(argc, argv);
 }
 
 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 {
-	no_replay = 0;
-	action = CHERRY_PICK;
+	flags = 0;
 	return revert_or_cherry_pick(argc, argv);
 }
diff --git a/pick.c b/pick.c
new file mode 100644
index 0000000..1e1628a
--- /dev/null
+++ b/pick.c
@@ -0,0 +1,218 @@
+#include "cache.h"
+#include "commit.h"
+#include "run-command.h"
+#include "cache-tree.h"
+#include "pick.h"
+#include "merge-recursive.h"
+
+static struct commit *commit;
+
+static char *get_oneline(const char *message)
+{
+	char *result;
+	const char *p = message, *abbrev, *eol;
+	int abbrev_len, oneline_len;
+
+	if (!p)
+		return NULL;
+	while (*p && (*p != '\n' || p[1] != '\n'))
+		p++;
+
+	if (*p) {
+		p += 2;
+		for (eol = p + 1; *eol && *eol != '\n'; eol++)
+			; /* do nothing */
+	} else
+		eol = p;
+	abbrev = find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV);
+	abbrev_len = strlen(abbrev);
+	oneline_len = eol - p;
+	result = xmalloc(abbrev_len + 5 + oneline_len);
+	memcpy(result, abbrev, abbrev_len);
+	memcpy(result + abbrev_len, "... ", 4);
+	memcpy(result + abbrev_len + 4, p, oneline_len);
+	result[abbrev_len + 4 + oneline_len] = '\0';
+	return result;
+}
+
+static void add_message_to_msg(struct strbuf *msg, const char *message)
+{
+	const char *p = message;
+	while (*p && (*p != '\n' || p[1] != '\n'))
+		p++;
+
+	if (!*p)
+		strbuf_addstr(msg, sha1_to_hex(commit->object.sha1));
+
+	p += 2;
+	strbuf_addstr(msg, p);
+	return;
+}
+
+static struct tree *empty_tree(void)
+{
+	struct tree *tree = xcalloc(1, sizeof(struct tree));
+
+	tree->object.parsed = 1;
+	tree->object.type = OBJ_TREE;
+	pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
+	return tree;
+}
+
+/*
+ * Pick changes introduced by "commit" argument into current working
+ * tree and index.
+ *
+ * It starts from the current index (not HEAD), and allow the effect
+ * of one commit replayed (either forward or backward) to that state,
+ * leaving the result in the index.
+ *
+ * You do not have to start from a commit, so you can replay many commits
+ * to the index in sequence without commiting in between to squash multiple
+ * steps if you wanted to.
+ *
+ * Return 0 on success.
+ * Return negative value on error before picking,
+ * and a positive value after picking,
+ * and return 1 if and only if a conflict occurs but no other error.
+ */
+int pick_commit(struct commit *pick_commit, int mainline, int flags,
+		struct strbuf *msg)
+{
+	unsigned char head[20];
+	struct commit *base, *next, *parent;
+	int i, index_fd, clean;
+	int ret = 0;
+	char *oneline;
+	const char *message;
+	struct merge_options o;
+	struct tree *result, *next_tree, *base_tree, *head_tree;
+	static struct lock_file index_lock;
+
+	strbuf_init(msg, 0);
+	commit = pick_commit;
+
+	/*
+	 * Let's compute the tree that represents the "current" state
+	 * for merge-recursive to work on.
+	 */
+	if (write_cache_as_tree(head, 0, NULL))
+		return error("Your index file is unmerged.");
+	discard_cache();
+
+	index_fd = hold_locked_index(&index_lock, 0);
+	if (index_fd < 0)
+		return error("Unable to create locked index: %s",
+			     strerror(errno));
+
+	if (!commit->parents) {
+		if (flags & PICK_REVERSE)
+			return error("Cannot revert a root commit");
+		parent = NULL;
+	}
+	else if (commit->parents->next) {
+		/* Reverting or cherry-picking a merge commit */
+		int cnt;
+		struct commit_list *p;
+
+		if (!mainline)
+			return error("Commit %s is a merge but no mainline was given.",
+				     sha1_to_hex(commit->object.sha1));
+
+		for (cnt = 1, p = commit->parents;
+		     cnt != mainline && p;
+		     cnt++)
+			p = p->next;
+		if (cnt != mainline || !p)
+			return error("Commit %s does not have parent %d",
+				     sha1_to_hex(commit->object.sha1),
+				     mainline);
+		parent = p->item;
+	} else if (0 < mainline)
+		return error("Mainline was specified but commit %s is not a merge.",
+			     sha1_to_hex(commit->object.sha1));
+	else
+		parent = commit->parents->item;
+
+	if (!(message = commit->buffer))
+		return error("Cannot get commit message for %s",
+			     sha1_to_hex(commit->object.sha1));
+
+	if (parent && parse_commit(parent) < 0)
+		return error("Cannot parse parent commit %s",
+			     sha1_to_hex(parent->object.sha1));
+
+	oneline = get_oneline(message);
+
+	if (flags & PICK_REVERSE) {
+		char *oneline_body = strchr(oneline, ' ') + 1;
+
+		base = commit;
+		next = parent;
+		strbuf_addstr(msg, "Revert \"");
+		strbuf_addstr(msg, oneline_body);
+		strbuf_addstr(msg, "\"\n\nThis reverts commit ");
+		strbuf_addstr(msg, sha1_to_hex(commit->object.sha1));
+
+		if (commit->parents->next) {
+			strbuf_addstr(msg, ", reversing\nchanges made to ");
+			strbuf_addstr(msg, sha1_to_hex(parent->object.sha1));
+		}
+		strbuf_addstr(msg, ".\n");
+	} else {
+		base = parent;
+		next = commit;
+		add_message_to_msg(msg, message);
+		if (flags & PICK_ADD_NOTE) {
+			strbuf_addstr(msg, "(cherry picked from commit ");
+			strbuf_addstr(msg, sha1_to_hex(commit->object.sha1));
+			strbuf_addstr(msg, ")\n");
+		}
+	}
+
+	read_cache();
+	init_merge_options(&o);
+	o.branch1 = "HEAD";
+	o.branch2 = oneline;
+
+	head_tree = parse_tree_indirect(head);
+	next_tree = next ? next->tree : empty_tree();
+	base_tree = base ? base->tree : empty_tree();
+
+	clean = merge_trees(&o,
+			    head_tree,
+			    next_tree, base_tree, &result);
+
+	if (active_cache_changed &&
+	    (write_cache(index_fd, active_cache, active_nr) ||
+	     commit_locked_index(&index_lock))) {
+		error("Unable to write new index file");
+		return 2;
+	}
+	rollback_lock_file(&index_lock);
+
+	if (!clean) {
+		strbuf_addstr(msg, "\nConflicts:\n\n");
+		for (i = 0; i < active_nr;) {
+			struct cache_entry *ce = active_cache[i++];
+			if (ce_stage(ce)) {
+				strbuf_addch(msg, '\t');
+				strbuf_addstr(msg, ce->name);
+				strbuf_addch(msg, '\n');
+				while (i < active_nr && !strcmp(ce->name,
+						active_cache[i]->name))
+					i++;
+			}
+		}
+		ret = 1;
+	}
+	free(oneline);
+
+	discard_cache();
+	if (read_cache() < 0) {
+		error("Cannot read the index");
+		return 2;
+	}
+
+	return ret;
+}
diff --git a/pick.h b/pick.h
new file mode 100644
index 0000000..7a74ad8
--- /dev/null
+++ b/pick.h
@@ -0,0 +1,13 @@
+#ifndef PICK_H
+#define PICK_H
+
+#include "commit.h"
+
+/* Pick flags: */
+#define PICK_REVERSE   1 /* pick the reverse changes ("revert") */
+#define PICK_ADD_NOTE  2 /* add note about original commit (unless conflict) */
+/* We don't need a PICK_QUIET. This is done by
+ *	setenv("GIT_MERGE_VERBOSITY", "0", 1); */
+extern int pick_commit(struct commit *commit, int mainline, int flags, struct strbuf *msg);
+
+#endif
-- 
1.6.6.1.557.g77031

[PATCH 2/9] reset: refactor updating heads into a static function

[Christian Couder]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin-reset.c |   43 +++++++++++++++++++++++++++----------------
 1 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/builtin-reset.c b/builtin-reset.c
index 0f5022e..3569695 100644
--- a/builtin-reset.c
+++ b/builtin-reset.c
@@ -211,15 +211,38 @@ static void prepend_reflog_action(const char *action, char *buf, size_t size)
 		warning("Reflog action message too long: %.*s...", 50, buf);
 }
 
+/*
+ * Any resets update HEAD to the head being switched to,
+ * saving the previous head in ORIG_HEAD before.
+ */
+static int update_heads(unsigned char *sha1)
+{
+	unsigned char sha1_orig[20], *orig = NULL,
+		sha1_old_orig[20], *old_orig = NULL;
+	char msg[1024];
+
+	if (!get_sha1("ORIG_HEAD", sha1_old_orig))
+		old_orig = sha1_old_orig;
+	if (!get_sha1("HEAD", sha1_orig)) {
+		orig = sha1_orig;
+		prepend_reflog_action("updating ORIG_HEAD", msg, sizeof(msg));
+		update_ref(msg, "ORIG_HEAD", orig, old_orig, 0, MSG_ON_ERR);
+	}
+	else if (old_orig)
+		delete_ref("ORIG_HEAD", old_orig, 0);
+	prepend_reflog_action("updating HEAD", msg, sizeof(msg));
+
+	return update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
+}
+
 int cmd_reset(int argc, const char **argv, const char *prefix)
 {
 	int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0;
 	int patch_mode = 0;
 	const char *rev = "HEAD";
-	unsigned char sha1[20], *orig = NULL, sha1_orig[20],
-				*old_orig = NULL, sha1_old_orig[20];
+	unsigned char sha1[20];
 	struct commit *commit;
-	char *reflog_action, msg[1024];
+	char *reflog_action;
 	const struct option options[] = {
 		OPT__QUIET(&quiet),
 		OPT_SET_INT(0, "mixed", &reset_type,
@@ -321,19 +344,7 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	else if (reset_index_file(sha1, reset_type, quiet))
 		die("Could not reset index file to revision '%s'.", rev);
 
-	/* Any resets update HEAD to the head being switched to,
-	 * saving the previous head in ORIG_HEAD before. */
-	if (!get_sha1("ORIG_HEAD", sha1_old_orig))
-		old_orig = sha1_old_orig;
-	if (!get_sha1("HEAD", sha1_orig)) {
-		orig = sha1_orig;
-		prepend_reflog_action("updating ORIG_HEAD", msg, sizeof(msg));
-		update_ref(msg, "ORIG_HEAD", orig, old_orig, 0, MSG_ON_ERR);
-	}
-	else if (old_orig)
-		delete_ref("ORIG_HEAD", old_orig, 0);
-	prepend_reflog_action("updating HEAD", msg, sizeof(msg));
-	update_ref_status = update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
+	update_ref_status = update_heads(sha1);
 
 	switch (reset_type) {
 	case HARD:
-- 
1.6.6.1.557.g77031

[PATCH 3/9] reset: refactor reseting in its own function

[Christian Couder]

This splits the reseting logic away from the argument parsing.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin-reset.c |  138 +++++++++++++++++++++++++++++-------------------------
 1 files changed, 74 insertions(+), 64 deletions(-)

diff --git a/builtin-reset.c b/builtin-reset.c
index 3569695..bf97931 100644
--- a/builtin-reset.c
+++ b/builtin-reset.c
@@ -235,68 +235,13 @@ static int update_heads(unsigned char *sha1)
 	return update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
 }
 
-int cmd_reset(int argc, const char **argv, const char *prefix)
+static int reset(const char *rev, const char *prefix,
+		 int reset_type, int quiet, int patch_mode,
+		 int argc, const char **argv)
 {
-	int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0;
-	int patch_mode = 0;
-	const char *rev = "HEAD";
-	unsigned char sha1[20];
 	struct commit *commit;
-	char *reflog_action;
-	const struct option options[] = {
-		OPT__QUIET(&quiet),
-		OPT_SET_INT(0, "mixed", &reset_type,
-						"reset HEAD and index", MIXED),
-		OPT_SET_INT(0, "soft", &reset_type, "reset only HEAD", SOFT),
-		OPT_SET_INT(0, "hard", &reset_type,
-				"reset HEAD, index and working tree", HARD),
-		OPT_SET_INT(0, "merge", &reset_type,
-				"reset HEAD, index and working tree", MERGE),
-		OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
-		OPT_END()
-	};
-
-	git_config(git_default_config, NULL);
-
-	argc = parse_options(argc, argv, prefix, options, git_reset_usage,
-						PARSE_OPT_KEEP_DASHDASH);
-	reflog_action = args_to_str(argv);
-	setenv("GIT_REFLOG_ACTION", reflog_action, 0);
-
-	/*
-	 * Possible arguments are:
-	 *
-	 * git reset [-opts] <rev> <paths>...
-	 * git reset [-opts] <rev> -- <paths>...
-	 * git reset [-opts] -- <paths>...
-	 * git reset [-opts] <paths>...
-	 *
-	 * At this point, argv[i] points immediately after [-opts].
-	 */
-
-	if (i < argc) {
-		if (!strcmp(argv[i], "--")) {
-			i++; /* reset to HEAD, possibly with paths */
-		} else if (i + 1 < argc && !strcmp(argv[i+1], "--")) {
-			rev = argv[i];
-			i += 2;
-		}
-		/*
-		 * Otherwise, argv[i] could be either <rev> or <paths> and
-		 * has to be unambiguous.
-		 */
-		else if (!get_sha1(argv[i], sha1)) {
-			/*
-			 * Ok, argv[i] looks like a rev; it should not
-			 * be a filename.
-			 */
-			verify_non_filename(prefix, argv[i]);
-			rev = argv[i++];
-		} else {
-			/* Otherwise we treat this as a filename */
-			verify_filename(prefix, argv[i]);
-		}
-	}
+	unsigned char sha1[20];
+	int update_ref_status;
 
 	if (get_sha1(rev, sha1))
 		die("Failed to resolve '%s' as a valid ref.", rev);
@@ -309,19 +254,19 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (patch_mode) {
 		if (reset_type != NONE)
 			die("--patch is incompatible with --{hard,mixed,soft}");
-		return interactive_reset(rev, argv + i, prefix);
+		return interactive_reset(rev, argv, prefix);
 	}
 
 	/* git reset tree [--] paths... can be used to
 	 * load chosen paths from the tree into the index without
 	 * affecting the working tree nor HEAD. */
-	if (i < argc) {
+	if (argc > 0) {
 		if (reset_type == MIXED)
 			warning("--mixed option is deprecated with paths.");
 		else if (reset_type != NONE)
 			die("Cannot do %s reset with paths.",
 					reset_type_names[reset_type]);
-		return read_from_tree(prefix, argv + i, sha1,
+		return read_from_tree(prefix, argv, sha1,
 				quiet ? REFRESH_QUIET : REFRESH_IN_PORCELAIN);
 	}
 	if (reset_type == NONE)
@@ -361,7 +306,72 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 
 	remove_branch_state();
 
+	return update_ref_status;
+}
+
+int cmd_reset(int argc, const char **argv, const char *prefix)
+{
+	int i = 0, reset_type = NONE, quiet = 0;
+	int patch_mode = 0;
+	const char *rev = "HEAD";
+	unsigned char sha1[20];
+	char *reflog_action;
+	const struct option options[] = {
+		OPT__QUIET(&quiet),
+		OPT_SET_INT(0, "mixed", &reset_type,
+						"reset HEAD and index", MIXED),
+		OPT_SET_INT(0, "soft", &reset_type, "reset only HEAD", SOFT),
+		OPT_SET_INT(0, "hard", &reset_type,
+				"reset HEAD, index and working tree", HARD),
+		OPT_SET_INT(0, "merge", &reset_type,
+				"reset HEAD, index and working tree", MERGE),
+		OPT_BOOLEAN('p', "patch", &patch_mode, "select hunks interactively"),
+		OPT_END()
+	};
+
+	git_config(git_default_config, NULL);
+
+	argc = parse_options(argc, argv, prefix, options, git_reset_usage,
+						PARSE_OPT_KEEP_DASHDASH);
+	reflog_action = args_to_str(argv);
+	setenv("GIT_REFLOG_ACTION", reflog_action, 0);
 	free(reflog_action);
 
-	return update_ref_status;
+	/*
+	 * Possible arguments are:
+	 *
+	 * git reset [-opts] <rev> <paths>...
+	 * git reset [-opts] <rev> -- <paths>...
+	 * git reset [-opts] -- <paths>...
+	 * git reset [-opts] <paths>...
+	 *
+	 * At this point, argv[i] points immediately after [-opts].
+	 */
+
+	if (i < argc) {
+		if (!strcmp(argv[i], "--")) {
+			i++; /* reset to HEAD, possibly with paths */
+		} else if (i + 1 < argc && !strcmp(argv[i+1], "--")) {
+			rev = argv[i];
+			i += 2;
+		}
+		/*
+		 * Otherwise, argv[i] could be either <rev> or <paths> and
+		 * has to be unambiguous.
+		 */
+		else if (!get_sha1(argv[i], sha1)) {
+			/*
+			 * Ok, argv[i] looks like a rev; it should not
+			 * be a filename.
+			 */
+			verify_non_filename(prefix, argv[i]);
+			rev = argv[i++];
+		} else {
+			/* Otherwise we treat this as a filename */
+			verify_filename(prefix, argv[i]);
+		}
+	}
+
+	return reset(rev, prefix, reset_type, quiet, patch_mode,
+		     argc - i, argv + i);
 }
-- 
1.6.6.1.557.g77031

[PATCH 4/9] reset: make reset function non static and declare it in "reset.h"

[Christian Couder]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin-reset.c |    8 ++++----
 reset.h         |   10 ++++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)
 create mode 100644 reset.h

diff --git a/builtin-reset.c b/builtin-reset.c
index bf97931..b004f9a 100644
--- a/builtin-reset.c
+++ b/builtin-reset.c
@@ -20,6 +20,7 @@
 #include "parse-options.h"
 #include "unpack-trees.h"
 #include "cache-tree.h"
+#include "reset.h"
 
 static const char * const git_reset_usage[] = {
 	"git reset [--mixed | --soft | --hard | --merge] [-q] [<commit>]",
@@ -27,7 +28,6 @@ static const char * const git_reset_usage[] = {
 	NULL
 };
 
-enum reset_type { MIXED, SOFT, HARD, MERGE, NONE };
 static const char *reset_type_names[] = { "mixed", "soft", "hard", "merge", NULL };
 
 static char *args_to_str(const char **argv)
@@ -235,9 +235,9 @@ static int update_heads(unsigned char *sha1)
 	return update_ref(msg, "HEAD", sha1, orig, 0, MSG_ON_ERR);
 }
 
-static int reset(const char *rev, const char *prefix,
-		 int reset_type, int quiet, int patch_mode,
-		 int argc, const char **argv)
+int reset(const char *rev, const char *prefix,
+	  int reset_type, int quiet, int patch_mode,
+	  int argc, const char **argv)
 {
 	struct commit *commit;
 	unsigned char sha1[20];
diff --git a/reset.h b/reset.h
new file mode 100644
index 0000000..c8497e4
--- /dev/null
+++ b/reset.h
@@ -0,0 +1,10 @@
+#ifndef RESET_H
+#define RESET_H
+
+enum reset_type { MIXED, SOFT, HARD, MERGE, NONE };
+
+int reset(const char *rev, const char *prefix,
+	  int reset_type, int quiet, int patch_mode,
+	  int argc, const char **argv);
+
+#endif
-- 
1.6.6.1.557.g77031

[PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Christian Couder]

As "git merge" fast forwards if possible, it seems sensible to
have such a feature for "git cherry-pick" too, especially as it
could be used in git-rebase--interactive.sh.

Maybe this option could be made the default in the long run, with
another --no-ff option to disable this default behavior, but that
could make some scripts backward incompatible and/or that would
require testing if some GIT_AUTHOR_* environment variables are
set. So we don't do that for now.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin-revert.c |   35 +++++++++++++++++++++++++++++++----
 1 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/builtin-revert.c b/builtin-revert.c
index 7488d4c..b78926f 100644
--- a/builtin-revert.c
+++ b/builtin-revert.c
@@ -9,6 +9,7 @@
 #include "revision.h"
 #include "rerere.h"
 #include "pick.h"
+#include "reset.h"
 
 /*
  * This implements the builtins revert and cherry-pick.
@@ -31,13 +32,19 @@ static const char * const cherry_pick_usage[] = {
 	NULL
 };
 
-static int edit, no_commit, mainline, signoff;
+static int edit, no_commit, mainline, signoff, ff_ok;
 static int flags;
 static struct commit *commit;
 static int allow_rerere_auto;
 
 #define GIT_REFLOG_ACTION "GIT_REFLOG_ACTION"
 
+static void die_if_ff_incompatible(int opt_set, const char *opt_name)
+{
+	if (opt_set)
+		die ("options --ff and %s are incompatible", opt_name);
+}
+
 static void parse_args(int argc, const char **argv)
 {
 	const char * const * usage_str =
@@ -51,6 +58,7 @@ static void parse_args(int argc, const char **argv)
 		OPT_BIT('x', NULL, &flags, "append commit name when cherry-picking", PICK_ADD_NOTE),
 		OPT_BOOLEAN('r', NULL, &noop, "no-op (backward compatibility)"),
 		OPT_BOOLEAN('s', "signoff", &signoff, "add Signed-off-by:"),
+		OPT_BOOLEAN(0, "ff", &ff_ok, "allow fast forward"),
 		OPT_INTEGER('m', "mainline", &mainline, "parent number"),
 		OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 		OPT_END(),
@@ -71,6 +79,12 @@ static void parse_args(int argc, const char **argv)
 	}
 	if (commit->object.type != OBJ_COMMIT)
 		die ("'%s' does not point to a commit", arg);
+	if (ff_ok) {
+		die_if_ff_incompatible(edit, "--edit");
+		die_if_ff_incompatible(flags & PICK_ADD_NOTE, "-x");
+		die_if_ff_incompatible(no_commit, "--no-commit");
+		die_if_ff_incompatible(signoff, "--signoff");
+	}
 }
 
 static char *get_encoding(const char *message)
@@ -191,7 +205,7 @@ static NORETURN void die_dirty_index(const char *me)
 	}
 }
 
-static int revert_or_cherry_pick(int argc, const char **argv)
+static int revert_or_cherry_pick(int argc, const char **argv, const char *prefix)
 {
 	const char *me;
 	struct strbuf msgbuf;
@@ -209,6 +223,19 @@ static int revert_or_cherry_pick(int argc, const char **argv)
 	if (!no_commit && index_differs_from("HEAD", 0))
 		die_dirty_index(me);
 
+	if (!(flags & PICK_REVERSE) && ff_ok && commit->parents) {
+		unsigned char head_sha1[20];
+		if (get_sha1("HEAD", head_sha1))
+			die("You do not have a valid HEAD.");
+		if (!hashcmp(commit->parents->item->object.sha1, head_sha1)) {
+			char *hex = sha1_to_hex(commit->object.sha1);
+			int res = reset(hex, prefix, HARD, 0, 0, 0, NULL);
+			if (!res)
+				fprintf(stderr, "Fast-forward to %s\n", hex);
+			return res;
+		}
+	}
+
 	if (!commit->buffer)
 		return error("Cannot get commit message for %s",
 				sha1_to_hex(commit->object.sha1));
@@ -270,11 +297,11 @@ int cmd_revert(int argc, const char **argv, const char *prefix)
 	if (isatty(0))
 		edit = 1;
 	flags = PICK_REVERSE | PICK_ADD_NOTE;
-	return revert_or_cherry_pick(argc, argv);
+	return revert_or_cherry_pick(argc, argv, prefix);
 }
 
 int cmd_cherry_pick(int argc, const char **argv, const char *prefix)
 {
 	flags = 0;
-	return revert_or_cherry_pick(argc, argv);
+	return revert_or_cherry_pick(argc, argv, prefix);
 }
-- 
1.6.6.1.557.g77031

[PATCH 6/9] cherry-pick: add tests for new --ff option

[Christian Couder]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t3506-cherry-pick-ff.sh |   38 ++++++++++++++++++++++++++++++++++++++
 1 files changed, 38 insertions(+), 0 deletions(-)
 create mode 100755 t/t3506-cherry-pick-ff.sh

diff --git a/t/t3506-cherry-pick-ff.sh b/t/t3506-cherry-pick-ff.sh
new file mode 100755
index 0000000..21c0729
--- /dev/null
+++ b/t/t3506-cherry-pick-ff.sh
@@ -0,0 +1,38 @@
+#!/bin/sh
+
+test_description='test cherry-picking with --ff option'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo first > file1 &&
+	git add file1 &&
+	test_tick &&
+	git commit -m "first" &&
+	git tag first &&
+
+	git checkout -b other &&
+	echo second >> file1 &&
+	git add file1 &&
+	test_tick &&
+	git commit -m "second" &&
+	git tag second
+'
+
+test_expect_success 'cherry-pick using --ff fast forwards' '
+	git checkout master &&
+	git reset --hard first &&
+	test_tick &&
+	git cherry-pick --ff second &&
+	test "$(git rev-parse --verify HEAD)" = "$(git rev-parse --verify second)"
+'
+
+test_expect_success 'cherry-pick not using --ff does not fast forwards' '
+	git checkout master &&
+	git reset --hard first &&
+	test_tick &&
+	git cherry-pick second &&
+	test "$(git rev-parse --verify HEAD)" != "$(git rev-parse --verify second)"
+'
+
+test_done
-- 
1.6.6.1.557.g77031

[PATCH 7/9] Documentation: describe new cherry-pick --ff option

[Christian Couder]

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 Documentation/git-cherry-pick.txt |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/Documentation/git-cherry-pick.txt b/Documentation/git-cherry-pick.txt
index 78f4714..d71607a 100644
--- a/Documentation/git-cherry-pick.txt
+++ b/Documentation/git-cherry-pick.txt
@@ -7,7 +7,7 @@ git-cherry-pick - Apply the change introduced by an existing commit
 
 SYNOPSIS
 --------
-'git cherry-pick' [--edit] [-n] [-m parent-number] [-s] [-x] <commit>
+'git cherry-pick' [--edit] [-n] [-m parent-number] [-s] [-x] [--ff] <commit>
 
 DESCRIPTION
 -----------
@@ -70,6 +70,10 @@ effect to your index in a row.
 --signoff::
 	Add Signed-off-by line at the end of the commit message.
 
+--ff::
+	If the current HEAD is the same as the parent of the
+	cherry-pick'ed commit, then a fast forward to this commit will
+	be performed.
 
 Author
 ------
-- 
1.6.6.1.557.g77031

[PATCH 8/9] rebase -i: use new --ff cherry-pick option

[Christian Couder]

This simplifies rebase -i a little bit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 git-rebase--interactive.sh |   15 +++------------
 1 files changed, 3 insertions(+), 12 deletions(-)

diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index c2f6089..6b224a6 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -222,8 +222,8 @@ do_with_author () {
 }
 
 pick_one () {
-	no_ff=
-	case "$1" in -n) sha1=$2; no_ff=t ;; *) sha1=$1 ;; esac
+	ff=--ff
+	case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac
 	output git rev-parse --verify $sha1 || die "Invalid commit name: $sha1"
 	test -d "$REWRITTEN" &&
 		pick_one_preserving_merges "$@" && return
@@ -232,16 +232,7 @@ pick_one () {
 		output git cherry-pick "$@"
 		return
 	fi
-	parent_sha1=$(git rev-parse --verify $sha1^) ||
-		die "Could not get the parent of $sha1"
-	current_sha1=$(git rev-parse --verify HEAD)
-	if test -z "$no_ff" && test "$current_sha1" = "$parent_sha1"
-	then
-		output git reset --hard $sha1
-		output warn Fast-forward to $(git rev-parse --short $sha1)
-	else
-		output git cherry-pick "$@"
-	fi
+	output git cherry-pick $ff "$@"
 }
 
 pick_one_preserving_merges () {
-- 
1.6.6.1.557.g77031

[PATCH 9/9] merge: use new "reset" function instead of running "git read-tree"

[Christian Couder]

This simplifies "git merge" code and make it more efficient in some
cases.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 builtin-merge.c |   31 +++++++++++--------------------
 1 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/builtin-merge.c b/builtin-merge.c
index 3aaec7b..de2343a 100644
--- a/builtin-merge.c
+++ b/builtin-merge.c
@@ -25,6 +25,7 @@
 #include "help.h"
 #include "merge-recursive.h"
 #include "resolve-undo.h"
+#include "reset.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -231,24 +232,14 @@ static void save_state(void)
 		die("not a valid object: %s", buffer.buf);
 }
 
-static void reset_hard(unsigned const char *sha1, int verbose)
+static void reset_hard(const char *prefix, unsigned const char *sha1, int verbose)
 {
-	int i = 0;
-	const char *args[6];
-
-	args[i++] = "read-tree";
-	if (verbose)
-		args[i++] = "-v";
-	args[i++] = "--reset";
-	args[i++] = "-u";
-	args[i++] = sha1_to_hex(sha1);
-	args[i] = NULL;
-
-	if (run_command_v_opt(args, RUN_GIT_CMD))
-		die("read-tree failed");
+	int res = reset(sha1_to_hex(sha1), prefix, HARD, !verbose, 0, 0, NULL);
+	if (res)
+		die("hard reset failed");
 }
 
-static void restore_state(void)
+static void restore_state(const char *prefix)
 {
 	struct strbuf sb = STRBUF_INIT;
 	const char *args[] = { "stash", "apply", NULL, NULL };
@@ -256,7 +247,7 @@ static void restore_state(void)
 	if (is_null_sha1(stash))
 		return;
 
-	reset_hard(head, 1);
+	reset_hard(prefix, head, 1);
 
 	args[2] = sha1_to_hex(stash);
 
@@ -970,7 +961,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			die("%s - not something we can merge", argv[0]);
 		update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
 				DIE_ON_ERR);
-		reset_hard(remote_head->sha1, 0);
+		reset_hard(prefix, remote_head->sha1, 0);
 		return 0;
 	} else {
 		struct strbuf msg = STRBUF_INIT;
@@ -1167,7 +1158,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		int ret;
 		if (i) {
 			printf("Rewinding the tree to pristine...\n");
-			restore_state();
+			restore_state(prefix);
 		}
 		if (use_strategies_nr != 1)
 			printf("Trying merge strategy %s...\n",
@@ -1228,7 +1219,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 	 * it up.
 	 */
 	if (!best_strategy) {
-		restore_state();
+		restore_state(prefix);
 		if (use_strategies_nr > 1)
 			fprintf(stderr,
 				"No merge strategy handled the merge.\n");
@@ -1240,7 +1231,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		; /* We already have its result in the working tree. */
 	else {
 		printf("Rewinding the tree to pristine...\n");
-		restore_state();
+		restore_state(prefix);
 		printf("Using the %s to prepare resolving by hand.\n",
 			best_strategy);
 		try_merge_strategy(best_strategy, common, head_arg);
-- 
1.6.6.1.557.g77031

Re: [PATCH 0/9] add --ff option to cherry-pick

[Junio C Hamano]

Christian Couder <chriscool@tuxfamily.org> writes:

> Changes since the previous series are the following:

Could you please briefly describe what good does "adding -ff option to
cherry-pick" do in the first place?

IOW, help reviewers to convince themselves that it is worth allocating a
block of time to read through a 9 patch series.  That is what the cover
letter is for.

Thanks.

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Junio C Hamano]

Christian Couder <chriscool@tuxfamily.org> writes:

> As "git merge" fast forwards if possible, it seems sensible to
> have such a feature for "git cherry-pick" too, especially as it
> could be used in git-rebase--interactive.sh.


> +	if (!(flags & PICK_REVERSE) && ff_ok && commit->parents) {
> +		unsigned char head_sha1[20];
> +		if (get_sha1("HEAD", head_sha1))
> +			die("You do not have a valid HEAD.");
> +		if (!hashcmp(commit->parents->item->object.sha1, head_sha1)) {
> +			char *hex = sha1_to_hex(commit->object.sha1);

With this check, you are saying:

	If we are cherry-picking commit $C, and if the current HEAD is
        the first parent of $C, then just reset to $C instead of running a
        cherry-pick.

I didn't check if you have access to commit->parents->item->object.sha1 at
this point in the codepath, though (e.g. have you parsed "commit" yet?).

If the goal is to make untouched 'pick' in rebase-i to fast forward
without actually running cherry-picking, perhaps it is much cleaner to do
this kind of comparison in the caller of cherry-pick (i.e. rebase-i and
anything that runs cherry-pick)?

The whole series is titled as if "cherry-pick --ff" is the primary goal,
but I am puzzled why earlier patches in the series were necessary for this
change.

Re: [PATCH 9/9] merge: use new "reset" function instead of running "git read-tree"

[Junio C Hamano]

Christian Couder <chriscool@tuxfamily.org> writes:

> This simplifies "git merge" code and make it more efficient in some
> cases.

I vaguely recall somebody (perhaps it was you) tried to do something like
this before to drive unpack_trees() inside the main process, broke the
program rather badly, and then we ended up keeping read-tree invocation
external to the process.  Am I misremembering things?

If not, could you describe how is this round different from the old one?

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Junio C Hamano]

Junio C Hamano <gitster@pobox.com> writes:

> Christian Couder <chriscool@tuxfamily.org> writes:
>
>> As "git merge" fast forwards if possible, it seems sensible to
>> have such a feature for "git cherry-pick" too, especially as it
>> could be used in git-rebase--interactive.sh.

One more thing, in the same part of the code:

>> +	if (!(flags & PICK_REVERSE) && ff_ok && commit->parents) {
>> +		unsigned char head_sha1[20];
>> +		if (get_sha1("HEAD", head_sha1))
>> +			die("You do not have a valid HEAD.");
>> +		if (!hashcmp(commit->parents->item->object.sha1, head_sha1)) {
>> +			char *hex = sha1_to_hex(commit->object.sha1);

Is there a need to check commit->parents->next?

Should this code work the same way if the commit being cherry-picked is a
merge?  Should "-m <parent-num>" option affect this codepath in any way?

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Paolo Bonzini]

On 02/06/2010 12:11 AM, Christian Couder wrote:
> As "git merge" fast forwards if possible, it seems sensible to
> have such a feature for "git cherry-pick" too, especially as it
> could be used in git-rebase--interactive.sh.
>
> Maybe this option could be made the default in the long run, with
> another --no-ff option to disable this default behavior, but that
> could make some scripts backward incompatible and/or that would
> require testing if some GIT_AUTHOR_* environment variables are
> set. So we don't do that for now.

I would still like to have a no-op --no-ff so that scripts that do rely 
on that can be future proofed (or also, scripts that do "git cherry-pick 
$blah -e COMMIT" could use --no-ff to avoid errors in case $blah 
contains --ff).

Paolo

Re: [PATCH 0/9] add --ff option to cherry-pick

[Christian Couder]

On samedi 06 février 2010, Junio C Hamano wrote:
> Christian Couder <chriscool@tuxfamily.org> writes:
> > Changes since the previous series are the following:
>
> Could you please briefly describe what good does "adding -ff option to
> cherry-pick" do in the first place?

Ok I will do that.

Thanks,
Christian.

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Christian Couder]

On samedi 06 février 2010, Paolo Bonzini wrote:
> On 02/06/2010 12:11 AM, Christian Couder wrote:
> > As "git merge" fast forwards if possible, it seems sensible to
> > have such a feature for "git cherry-pick" too, especially as it
> > could be used in git-rebase--interactive.sh.
> >
> > Maybe this option could be made the default in the long run, with
> > another --no-ff option to disable this default behavior, but that
> > could make some scripts backward incompatible and/or that would
> > require testing if some GIT_AUTHOR_* environment variables are
> > set. So we don't do that for now.
>
> I would still like to have a no-op --no-ff so that scripts that do rely
> on that can be future proofed (or also, scripts that do "git cherry-pick
> $blah -e COMMIT" could use --no-ff to avoid errors in case $blah
> contains --ff).

Ok, I will add a --no-ff option but I think it should be incompatible 
with --ff rather than overide it.

Thanks,
Christian.

Re: [PATCH 9/9] merge: use new "reset" function instead of running "git read-tree"

[Christian Couder]

On samedi 06 février 2010, Junio C Hamano wrote:
> Christian Couder <chriscool@tuxfamily.org> writes:
> > This simplifies "git merge" code and make it more efficient in some
> > cases.
>
> I vaguely recall somebody (perhaps it was you) tried to do something like
> this before to drive unpack_trees() inside the main process, broke the
> program rather badly, and then we ended up keeping read-tree invocation
> external to the process.  Am I misremembering things?

I don't think it was me and I don't recall that, but I don't follow all the 
threads on the mailing list.

I will search the archive, but any pointer would be very appreciated.

Thanks anyway,
Christian.

> If not, could you describe how is this round different from the old one?

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Paolo Bonzini]

On 02/06/2010 04:29 PM, Christian Couder wrote:
> On samedi 06 février 2010, Paolo Bonzini wrote:
>> On 02/06/2010 12:11 AM, Christian Couder wrote:
>>> As "git merge" fast forwards if possible, it seems sensible to
>>> have such a feature for "git cherry-pick" too, especially as it
>>> could be used in git-rebase--interactive.sh.
>>>
>>> Maybe this option could be made the default in the long run, with
>>> another --no-ff option to disable this default behavior, but that
>>> could make some scripts backward incompatible and/or that would
>>> require testing if some GIT_AUTHOR_* environment variables are
>>> set. So we don't do that for now.
>>
>> I would still like to have a no-op --no-ff so that scripts that do rely
>> on that can be future proofed (or also, scripts that do "git cherry-pick
>> $blah -e COMMIT" could use --no-ff to avoid errors in case $blah
>> contains --ff).
>
> Ok, I will add a --no-ff option but I think it should be incompatible
> with --ff rather than overide it.

Whatever it does it should be the same as git merge.

Paolo

Re: [PATCH 5/9] revert: add --ff option to allow fast forward when cherry-picking

[Christian Couder]

On Saturday 06 February 2010 00:57:18 Junio C Hamano wrote:
> Christian Couder <chriscool@tuxfamily.org> writes:
> > As "git merge" fast forwards if possible, it seems sensible to
> > have such a feature for "git cherry-pick" too, especially as it
> > could be used in git-rebase--interactive.sh.
> >
> >
> > +	if (!(flags & PICK_REVERSE) && ff_ok && commit->parents) {
> > +		unsigned char head_sha1[20];
> > +		if (get_sha1("HEAD", head_sha1))
> > +			die("You do not have a valid HEAD.");
> > +		if (!hashcmp(commit->parents->item->object.sha1, head_sha1)) {
> > +			char *hex = sha1_to_hex(commit->object.sha1);
> 
> With this check, you are saying:
> 
> 	If we are cherry-picking commit $C, and if the current HEAD is
>         the first parent of $C, then just reset to $C instead of running a
>         cherry-pick.
> 
> I didn't check if you have access to commit->parents->item->object.sha1 at
> this point in the codepath, though (e.g. have you parsed "commit" yet?).

Yes it is parsed by the call to lookup_commit_reference() in parse_args().

> If the goal is to make untouched 'pick' in rebase-i to fast forward
> without actually running cherry-picking, perhaps it is much cleaner to do
> this kind of comparison in the caller of cherry-pick (i.e. rebase-i and
> anything that runs cherry-pick)?

At least Daniel Barkalow and Paolo Bonzini have stated before that they would 
find natural that git cherry-pick itself can fast forward.

The argument in the commit message is that as "git merge" can and does fast 
forward by default it seems strange that "git cherry-pick" cannot fast 
forward. It's not just because rebase-i tries to fast forward, as I think it 
is just simpler to fast forward if possible when using cherry-pick by hand.

> The whole series is titled as if "cherry-pick --ff" is the primary goal,
> but I am puzzled why earlier patches in the series were necessary for this
> change.

Earlier patches are just refactoring and making the needed functions extern to 
make the implementation of cherry-pick --ff possible and clean.

> One more thing, in the same part of the code:
> >> +	if (!(flags & PICK_REVERSE) && ff_ok && commit->parents) {
> >> +		unsigned char head_sha1[20];
> >> +		if (get_sha1("HEAD", head_sha1))
> >> +			die("You do not have a valid HEAD.");
> >> +		if (!hashcmp(commit->parents->item->object.sha1, head_sha1)) {
> >> +			char *hex = sha1_to_hex(commit->object.sha1);
> 
> Is there a need to check commit->parents->next?
> 
> Should this code work the same way if the commit being cherry-picked is a
> merge?  Should "-m <parent-num>" option affect this codepath in any way?

Yeah I had not even checked what happens with merge commits and/or "-m 
<parent-num>". The next version of the patch series takes care of that.

Thanks,
Christian.