[PATCH 2/2] git-add: introduce --edit (to edit the diff vs. the index)

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

With "git add -e [<files>]", Git will fire up an editor with the current
diff relative to the index (i.e. what you would get with "git diff
[<files>]").

Now you can edit the patch as much as you like, including adding/removing
lines, editing the text, whatever.  Make sure, though, that the first
character of the hunk lines is still a space, a plus or a minus.

After you closed the editor, Git will adjust the line counts of the
hunks if necessary, thanks to the --fixup-line-counts option of apply,
and commit the patch.  Except if you deleted everything, in which case
nothing happens (for obvious reasons).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---

	This was too useful to let slip by.  I even committed it using 
	"git add -e <files>" several times!

	Anyway, bed time.

 Documentation/git-add.txt |    9 ++++++-
 builtin-add.c             |   49 ++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/Documentation/git-add.txt b/Documentation/git-add.txt
index 1afd0c6..dd744f1 100644
--- a/Documentation/git-add.txt
+++ b/Documentation/git-add.txt
@@ -8,8 +8,8 @@ git-add - Add file contents to the index
 SYNOPSIS
 --------
 [verse]
-'git-add' [-n] [-v] [-f] [--interactive | -i] [--patch | -p] [-u] [--refresh]
-	  [--ignore-errors] [--] <filepattern>...
+'git-add' [-n] [-v] [-f] [--interactive | -i] [--patch | -p] [--edit | -e]
+	  [-u] [--refresh] [--ignore-errors] [--] <filepattern>...
 
 DESCRIPTION
 -----------
@@ -70,6 +70,11 @@ OPTIONS
 	bypassed and the 'patch' subcommand is invoked using each of
 	the specified filepatterns before exiting.
 
+-e, \--edit::
+	Open the diff vs. the index in an editor and let the user
+	edit it.  After the editor was closed, adjust the hunk headers
+	and apply the patch to the index.
+
 -u::
 	Update only files that git already knows about, staging modified
 	content for commit and marking deleted files for removal. This
diff --git a/builtin-add.c b/builtin-add.c
index 1da22ee..05ae40d 100644
--- a/builtin-add.c
+++ b/builtin-add.c
@@ -19,7 +19,7 @@ static const char * const builtin_add_usage[] = {
 	"git-add [options] [--] <filepattern>...",
 	NULL
 };
-static int patch_interactive = 0, add_interactive = 0;
+static int patch_interactive = 0, add_interactive = 0, edit_interactive = 0;
 static int take_worktree_changes;
 
 static void prune_directory(struct dir_struct *dir, const char **pathspec, int prefix)
@@ -186,6 +186,50 @@ int interactive_add(int argc, const char **argv, const char *prefix)
 	return status;
 }
 
+int edit_patch(int argc, const char **argv, const char *prefix)
+{
+	static struct lock_file lock;
+	struct child_process child;
+	int ac;
+	struct stat st;
+
+	memset(&child, 0, sizeof(child));
+	child.argv = xcalloc(sizeof(const char *), (argc + 5));
+	ac = 0;
+	child.git_cmd = 1;
+	child.argv[ac++] = "diff-files";
+	child.argv[ac++] = "--no-color";
+	child.argv[ac++] = "-p";
+	child.argv[ac++] = "--";
+	if (argc) {
+		const char **pathspec = validate_pathspec(argc, argv, prefix);
+		if (!pathspec)
+			return -1;
+		memcpy(&(child.argv[ac]), pathspec, sizeof(*argv) * argc);
+		ac += argc;
+	}
+	child.argv[ac] = NULL;
+	child.out = hold_lock_file_for_update(&lock, git_path("EDIT_PATCH"), 1);
+
+	if (run_command(&child))
+		return 1;
+	free(child.argv);
+
+	launch_editor(lock.filename, NULL, NULL);
+
+	if (stat(lock.filename, &st))
+		return 1;
+	if (!st.st_size) {
+		fprintf(stderr, "Empty patch. Aborted.\n");
+		return 0;
+	}
+
+	execl_git_cmd("apply", "--fixup-line-counts", "--cached",
+			lock.filename, NULL);
+
+	return 1;
+}
+
 static struct lock_file lock_file;
 
 static const char ignore_error[] =
@@ -200,6 +244,7 @@ static struct option builtin_add_options[] = {
 	OPT_GROUP(""),
 	OPT_BOOLEAN('i', "interactive", &add_interactive, "interactive picking"),
 	OPT_BOOLEAN('p', "patch", &patch_interactive, "interactive patching"),
+	OPT_BOOLEAN('e', "edit", &edit_interactive, "super-interactive patching"),
 	OPT_BOOLEAN('f', NULL, &ignored_too, "allow adding otherwise ignored files"),
 	OPT_BOOLEAN('u', NULL, &take_worktree_changes, "update tracked files"),
 	OPT_BOOLEAN( 0 , "refresh", &refresh_only, "don't add, only refresh the index"),
@@ -226,6 +271,8 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	argc = parse_options(argc, argv, builtin_add_options,
 			  builtin_add_usage, 0);
+	if (edit_interactive)
+		return(edit_patch(argc, argv, prefix));
 	if (patch_interactive)
 		add_interactive = 1;
 	if (add_interactive)
-- 
1.5.6.rc1.181.gb439d