Merge branch 'jc/index-output'

* jc/index-output:
  git-read-tree --index-output=<file>
  _GIT_INDEX_OUTPUT: allow plumbing to output to an alternative index file.

Conflicts:

	builtin-apply.c

13 files changed, 66 insertions, 25 deletions

diff --git a/Documentation/git-read-tree.txt b/Documentation/git-read-tree.txt
index 0ff2890..019c8be 100644
--- a/Documentation/git-read-tree.txt
+++ b/Documentation/git-read-tree.txt
@@ -8,7 +8,7 @@ git-read-tree - Reads tree information into the index
 
 SYNOPSIS
 --------
-'git-read-tree' (<tree-ish> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] [--exclude-per-directory=<gitignore>] <tree-ish1> [<tree-ish2> [<tree-ish3>]])
+'git-read-tree' (<tree-ish> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] [--exclude-per-directory=<gitignore>] [--index-output=<file>] <tree-ish1> [<tree-ish2> [<tree-ish3>]])
 
 
 DESCRIPTION
@@ -86,6 +86,18 @@ OPTIONS
 	file (usually '.gitignore') and allows such an untracked
 	but explicitly ignored file to be overwritten.
 
+--index-output=<file>::
+	Instead of writing the results out to `$GIT_INDEX_FILE`,
+	write the resulting index in the named file.  While the
+	command is operating, the original index file is locked
+	with the same mechanism as usual.  The file must allow
+	to be rename(2)ed into from a temporary file that is
+	created next to the usual index file; typically this
+	means it needs to be on the same filesystem as the index
+	file itself, and you need write permission to the
+	directories the index file and index output file are
+	located in.
+
 <tree-ish#>::
 	The id of the tree object(s) to be read/merged.
 
diff --git a/builtin-add.c b/builtin-add.c
index 7d1d5dc..9ec2925 100644
--- a/builtin-add.c
+++ b/builtin-add.c
@@ -133,7 +133,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	git_config(git_add_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
+	newfd = hold_locked_index(&lock_file, 1);
 
 	for (i = 1; i < argc; i++) {
 		const char *arg = argv[i];
@@ -209,7 +209,7 @@ int cmd_add(int argc, const char **argv, const char *prefix)
 
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    close(newfd) || commit_lock_file(&lock_file))
+		    close(newfd) || commit_locked_index(&lock_file))
 			die("Unable to write new index file");
 	}
 
diff --git a/builtin-apply.c b/builtin-apply.c
index 4b8311b..fd92ef7 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -2664,8 +2664,8 @@ static int apply_patch(int fd, const char *filename, int inaccurate_eof)
 
 	update_index = check_index && apply;
 	if (update_index && newfd < 0)
-		newfd = hold_lock_file_for_update(&lock_file,
-						  get_index_file(), 1);
+		newfd = hold_locked_index(&lock_file, 1);
+
 	if (check_index) {
 		if (read_cache() < 0)
 			die("unable to read index file");
@@ -2872,7 +2872,7 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 
 	if (update_index) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    close(newfd) || commit_lock_file(&lock_file))
+		    close(newfd) || commit_locked_index(&lock_file))
 			die("Unable to write new index file");
 	}
 
diff --git a/builtin-checkout-index.c b/builtin-checkout-index.c
index afe4b0e..8460f97 100644
--- a/builtin-checkout-index.c
+++ b/builtin-checkout-index.c
@@ -202,10 +202,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 		if (!strcmp(arg, "-u") || !strcmp(arg, "--index")) {
 			state.refresh_cache = 1;
 			if (newfd < 0)
-				newfd = hold_lock_file_for_update
-					(&lock_file, get_index_file(), 1);
-			if (newfd < 0)
-				die("cannot open index.lock file.");
+				newfd = hold_locked_index(&lock_file, 1);
 			continue;
 		}
 		if (!strcmp(arg, "-z")) {
@@ -302,7 +299,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 
 	if (0 <= newfd &&
 	    (write_cache(newfd, active_cache, active_nr) ||
-	     close(newfd) || commit_lock_file(&lock_file)))
+	     close(newfd) || commit_locked_index(&lock_file)))
 		die("Unable to write new index file");
 	return 0;
 }
diff --git a/builtin-mv.c b/builtin-mv.c
index c4ab478..3563216 100644
--- a/builtin-mv.c
+++ b/builtin-mv.c
@@ -77,7 +77,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
+	newfd = hold_locked_index(&lock_file, 1);
 	if (read_cache() < 0)
 		die("index file corrupt");
 
@@ -285,7 +285,7 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 		if (active_cache_changed) {
 			if (write_cache(newfd, active_cache, active_nr) ||
 			    close(newfd) ||
-			    commit_lock_file(&lock_file))
+			    commit_locked_index(&lock_file))
 				die("Unable to write new index file");
 		}
 	}
diff --git a/builtin-read-tree.c b/builtin-read-tree.c
index 793eae0..213bd93 100644
--- a/builtin-read-tree.c
+++ b/builtin-read-tree.c
@@ -84,7 +84,7 @@ static void prime_cache_tree(void)
 
 }
 
-static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] [--exclude-per-directory=<gitignore>] <sha1> [<sha2> [<sha3>]])";
+static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] [--exclude-per-directory=<gitignore>] [--index-output=<file>] <sha1> [<sha2> [<sha3>]])";
 
 static struct lock_file lock_file;
 
@@ -100,7 +100,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	setup_git_directory();
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
+	newfd = hold_locked_index(&lock_file, 1);
 
 	git_config(git_default_config);
 
@@ -128,6 +128,11 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 			continue;
 		}
 
+		if (!prefixcmp(arg, "--index-output=")) {
+			set_alternate_index_output(arg + 15);
+			continue;
+		}
+
 		/* "--prefix=<subdirectory>/" means keep the current index
 		 *  entries and put the entries from the tree under the
 		 * given subdirectory.
@@ -267,7 +272,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 	}
 
 	if (write_cache(newfd, active_cache, active_nr) ||
-	    close(newfd) || commit_lock_file(&lock_file))
+	    close(newfd) || commit_locked_index(&lock_file))
 		die("unable to write new index file");
 	return 0;
 }
diff --git a/builtin-rm.c b/builtin-rm.c
index bf42003..8a0738f 100644
--- a/builtin-rm.c
+++ b/builtin-rm.c
@@ -110,7 +110,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config);
 
-	newfd = hold_lock_file_for_update(&lock_file, get_index_file(), 1);
+	newfd = hold_locked_index(&lock_file, 1);
 
 	if (read_cache() < 0)
 		die("index file corrupt");
@@ -220,7 +220,7 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	if (active_cache_changed) {
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    close(newfd) || commit_lock_file(&lock_file))
+		    close(newfd) || commit_locked_index(&lock_file))
 			die("Unable to write new index file");
 	}
 
diff --git a/builtin-update-index.c b/builtin-update-index.c
index d1e5cf7..47d42ed 100644
--- a/builtin-update-index.c
+++ b/builtin-update-index.c
@@ -495,7 +495,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	/* We can't free this memory, it becomes part of a linked list parsed atexit() */
 	lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_lock_file_for_update(lock_file, get_index_file(), 0);
+	newfd = hold_locked_index(lock_file, 0);
 	if (newfd < 0)
 		lock_error = errno;
 
@@ -661,7 +661,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 			    get_index_file(), strerror(lock_error));
 		}
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    close(newfd) || commit_lock_file(lock_file))
+		    close(newfd) || commit_locked_index(lock_file))
 			die("Unable to write new index file");
 	}
 
diff --git a/builtin-write-tree.c b/builtin-write-tree.c
index 90fc1cf..c88bbd1 100644
--- a/builtin-write-tree.c
+++ b/builtin-write-tree.c
@@ -18,7 +18,7 @@ int write_tree(unsigned char *sha1, int missing_ok, const char *prefix)
 	/* We can't free this memory, it becomes part of a linked list parsed atexit() */
 	struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_lock_file_for_update(lock_file, get_index_file(), 0);
+	newfd = hold_locked_index(lock_file, 1);
 
 	entries = read_cache();
 	if (entries < 0)
diff --git a/cache.h b/cache.h
index ece0c04..1b50c32 100644
--- a/cache.h
+++ b/cache.h
@@ -211,6 +211,11 @@ struct lock_file {
 };
 extern int hold_lock_file_for_update(struct lock_file *, const char *path, int);
 extern int commit_lock_file(struct lock_file *);
+
+extern int hold_locked_index(struct lock_file *, int);
+extern int commit_locked_index(struct lock_file *);
+extern void set_alternate_index_output(const char *);
+
 extern void rollback_lock_file(struct lock_file *);
 extern int delete_ref(const char *, unsigned char *sha1);
 
diff --git a/git-commit.sh b/git-commit.sh
index 292cf96..9e0959a 100755
--- a/git-commit.sh
+++ b/git-commit.sh
@@ -370,8 +370,8 @@ t,)
 		# the same way.
 		if test -z "$initial_commit"
 		then
-			cp "$THIS_INDEX" "$TMP_INDEX"
-			GIT_INDEX_FILE="$TMP_INDEX" git-read-tree -i -m HEAD
+			GIT_INDEX_FILE="$THIS_INDEX" \
+			git-read-tree --index-output="$TMP_INDEX" -i -m HEAD
 		else
 			rm -f "$TMP_INDEX"
 		fi || exit
diff --git a/lockfile.c b/lockfile.c
index 4824f4d..bed6b21 100644
--- a/lockfile.c
+++ b/lockfile.c
@@ -4,6 +4,7 @@
 #include "cache.h"
 
 static struct lock_file *lock_file_list;
+static const char *alternate_index_output;
 
 static void remove_lock_file(void)
 {
@@ -65,6 +66,27 @@ int commit_lock_file(struct lock_file *lk)
 	return i;
 }
 
+int hold_locked_index(struct lock_file *lk, int die_on_error)
+{
+	return hold_lock_file_for_update(lk, get_index_file(), die_on_error);
+}
+
+void set_alternate_index_output(const char *name)
+{
+	alternate_index_output = name;
+}
+
+int commit_locked_index(struct lock_file *lk)
+{
+	if (alternate_index_output) {
+		int result = rename(lk->filename, alternate_index_output);
+		lk->filename[0] = 0;
+		return result;
+	}
+	else
+		return commit_lock_file(lk);
+}
+
 void rollback_lock_file(struct lock_file *lk)
 {
 	if (lk->filename[0])
diff --git a/merge-recursive.c b/merge-recursive.c
index 3611a2b..2b614b6 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1378,7 +1378,7 @@ int main(int argc, char *argv[])
 	if (show(3))
 		printf("Merging %s with %s\n", branch1, branch2);
 
-	index_fd = hold_lock_file_for_update(lock, get_index_file(), 1);
+	index_fd = hold_locked_index(lock, 1);
 
 	for (i = 0; i < bases_count; i++) {
 		struct commit *ancestor = get_ref(bases[i]);
@@ -1388,7 +1388,7 @@ int main(int argc, char *argv[])
 
 	if (active_cache_changed &&
 	    (write_cache(index_fd, active_cache, active_nr) ||
-	     close(index_fd) || commit_lock_file(lock)))
+	     close(index_fd) || commit_locked_index(lock)))
 			die ("unable to write %s", get_index_file());
 
 	return clean ? 0: 1;