[PATCH] Add support for GIT_ONE_FILESYSTEM

[Lars Damerow <lars@pixar.com>]

This patch makes git pay attention to the GIT_ONE_FILESYSTEM environment
variable. When that variable is set, git will stop searching for a
GIT_DIR when it attempts to cross a filesystem boundary.

When working in an environment with too many automount points to make
maintaining a GIT_CEILING_DIRECTORIES list enjoyable, GIT_ONE_FILESYSTEM
gives the option of turning all such attempts off with one setting.

Signed-off-by: Lars R. Damerow <lars@pixar.com>
---
 Documentation/git.txt |    3 +++
 setup.c               |   11 +++++++++++
 2 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/Documentation/git.txt b/Documentation/git.txt
index 35c0c79..dbb590f 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -529,6 +529,9 @@ git so take care if using Cogito etc.
 	a GIT_DIR set on the command line or in the environment.
 	(Useful for excluding slow-loading network directories.)
 
+'GIT_ONE_FILESYSTEM'::
+	Stop at filesystem boundaries when looking for .git or objects.
+
 git Commits
 ~~~~~~~~~~~
 'GIT_AUTHOR_NAME'::
diff --git a/setup.c b/setup.c
index 5716d90..63dc52e 100644
--- a/setup.c
+++ b/setup.c
@@ -323,6 +323,8 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	const char *gitdirenv;
 	const char *gitfile_dir;
 	int len, offset, ceil_offset, root_len;
+	int current_device = 0;
+	struct stat buf;
 
 	/*
 	 * Let's assume that we are in a git repository.
@@ -390,6 +392,9 @@ const char *setup_git_directory_gently(int *nongit_ok)
 	 *   etc.
 	 */
 	offset = len = strlen(cwd);
+	if (stat(".", &buf))
+		die_errno("failed to stat '.'");
+	current_device = buf.st_dev;
 	for (;;) {
 		gitfile_dir = read_gitfile_gently(DEFAULT_GIT_DIR_ENVIRONMENT);
 		if (gitfile_dir) {
@@ -422,6 +427,12 @@ const char *setup_git_directory_gently(int *nongit_ok)
 			}
 			die("Not a git repository (or any of the parent directories): %s", DEFAULT_GIT_DIR_ENVIRONMENT);
 		}
+		if (getenv("GIT_ONE_FILESYSTEM") != NULL) {
+			if (stat("..", &buf))
+				die_errno("failed to stat '..'");
+			if (buf.st_dev != current_device)
+				die("refusing to cross filesystem boundary '%s/..'", cwd);
+		}
 		if (chdir(".."))
 			die_errno("Cannot change to '%s/..'", cwd);
 	}
-- 
1.6.5.2