[PATCH] commit: allow partial commits with relative paths

[Clemens Buchacher <drizzd@aon.at>]

In order to do partial commits, git-commit overlays a tree on the
cache and checks pathspecs against the result. Currently, the overlaying
is done using "prefix" which prevents relative pathspecs with ".." and
absolute pathspec from matching when they refer to files not under
"prefix" and absent from the index, but still in the tree (i.e. files
staged for removal).

Instead, determine the maximal common prefix for all specified
paths using the pathspec_prefix() routine from ls-files.c.  Any use
of global variables is removed from pathspec_prefix() so that it
can be called from commit.c.

Reported-by: Reuben Thomas <rrt@sc3d.org>
Analyzed-by: Michael J Gruber <git@drmicha.warpmail.net>
Signed-off-by: Clemens Buchacher <drizzd@aon.at>

On Mon, Jul 25, 2011 at 09:42:10AM +0200, Michael J Gruber wrote:
> 
> Overlay the full tree instead.

That is one option. On the other hand, ls-files already provides
the function we need to do this properly.

With your permission I am stealing your commit message.

Clemens
---
 builtin/commit.c   |    6 ++++--
 builtin/ls-files.c |   38 ++------------------------------------
 cache.h            |    1 +
 setup.c            |   32 ++++++++++++++++++++++++++++++++
 4 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index a16d00b..c2db12a 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -256,8 +256,10 @@ static int list_paths(struct string_list *list, const char *with_tree,
 		;
 	m = xcalloc(1, i);
 
-	if (with_tree)
-		overlay_tree_on_cache(with_tree, prefix);
+	if (with_tree) {
+		const char *max_prefix = pathspec_prefix(prefix, pattern);
+		overlay_tree_on_cache(with_tree, max_prefix);
+	}
 
 	for (i = 0; i < active_nr; i++) {
 		struct cache_entry *ce = active_cache[i];
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 72b986f..fef5642 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -276,41 +276,6 @@ static void prune_cache(const char *prefix)
 	active_nr = last;
 }
 
-static const char *pathspec_prefix(const char *prefix)
-{
-	const char **p, *n, *prev;
-	unsigned long max;
-
-	if (!pathspec) {
-		max_prefix_len = prefix ? strlen(prefix) : 0;
-		return prefix;
-	}
-
-	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 == '*' || c == '?')
-				break;
-			if (c == '/')
-				len = i+1;
-		}
-		prev = n;
-		if (len < max) {
-			max = len;
-			if (!max)
-				break;
-		}
-	}
-
-	max_prefix_len = max;
-	return max ? xmemdupz(prev, max) : NULL;
-}
-
 static void strip_trailing_slash_from_submodules(void)
 {
 	const char **p;
@@ -581,7 +546,8 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 		strip_trailing_slash_from_submodules();
 
 	/* Find common prefix for all pathspec's */
-	max_prefix = pathspec_prefix(prefix);
+	max_prefix = pathspec_prefix(prefix, pathspec);
+	max_prefix_len = max_prefix ? strlen(max_prefix) : 0;
 
 	/* Treat unmatching pathspec elements as errors */
 	if (pathspec && error_unmatch) {
diff --git a/cache.h b/cache.h
index 86518fb..dd3edaa 100644
--- a/cache.h
+++ b/cache.h
@@ -441,6 +441,7 @@ extern void set_git_work_tree(const char *tree);
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
 extern const char **get_pathspec(const char *prefix, const char **pathspec);
+extern const char *pathspec_prefix(const char *prefix, const char **pathspec);
 extern void setup_work_tree(void);
 extern const char *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
diff --git a/setup.c b/setup.c
index 5ea5502..2c51a9a 100644
--- a/setup.c
+++ b/setup.c
@@ -264,6 +264,38 @@ const char **get_pathspec(const char *prefix, const char **pathspec)
 	return pathspec;
 }
 
+const char *pathspec_prefix(const char *prefix, const char **pathspec)
+{
+	const char **p, *n, *prev;
+	unsigned long max;
+
+	if (!pathspec)
+		return prefix ? xmemdupz(prefix, strlen(prefix)) : NULL;
+
+	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 == '*' || c == '?')
+				break;
+			if (c == '/')
+				len = i+1;
+		}
+		prev = n;
+		if (len < max) {
+			max = len;
+			if (!max)
+				break;
+		}
+	}
+
+	return max ? xmemdupz(prev, max) : NULL;
+}
+
 /*
  * Test if it looks like we're at a git directory.
  * We want to see:
-- 
1.7.3.1.105.g84915