[PATCH v2] Add command line option --chdir/-C to allow setting git process work directory.

Maciej Pasternacki· Oct 19, 2008, 16:18 UTC · lore

When "git pull" is ran outside of work tree, it is unable to update work tree with pulled changes; specifying --git-dir and --work-tree does not help here because "cd_to_toplevel" call in git-pull occurs after "require_work_tree"; changing order may break the commend if there is no working tree. Some more commands behave in a similar way.

In my project, I need to call "git pull" from outside of work tree, but I need it to update the work tree. It seems to require doing chdir() before running git, but this is problematic thing to do in the calling program because of portability issues. Proper solution seems to be providing -C / --chdir command line option, similar to this of Make, that would make main git program perform chdir() to specified directory before running the specific command. This would make using git from outside programs much more straightforward.

This patch provides -C and --chdir command line options that behave as described above.

Signed-off-by: Maciej Pasternacki <maciej@pasternacki.net>
---
 Documentation/git.txt |    6 +++++-
 git.c                 |   19 ++++++++++++++++++-
 2 files changed, 23 insertions(+), 2 deletions(-)

Show changes to 2 files +23 −2

Documentation/git.txt, git.c

diff --git a/Documentation/git.txt b/Documentation/git.txt
index df420ae..6676d68 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -12,7 +12,7 @@ SYNOPSIS
 'git' [--version] [--exec-path[=GIT_EXEC_PATH]]
     [-p|--paginate|--no-pager]
     [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE]
-    [--help] COMMAND [ARGS]
+    [-C DIRECTORY|--chdir=DIRECTORY] [--help] COMMAND [ARGS]
 
 DESCRIPTION
 -----------
@@ -185,6 +185,10 @@ help ...`.
 	environment is not set, it is set to the current working
 	directory.
 
+-C <directory>::
+--chdir=<directory>::
+	Change working directory before doing anything.
+
 
 FURTHER DOCUMENTATION
 ---------------------
diff --git a/git.c b/git.c
index 89feb0b..c63d754 100644
--- a/git.c
+++ b/git.c
@@ -4,7 +4,7 @@
 #include "quote.h"
 
 const char git_usage_string[] =
-	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [--help] COMMAND [ARGS]";
+	"git [--version] [--exec-path[=GIT_EXEC_PATH]] [-p|--paginate|--no-pager] [--bare] [--git-dir=GIT_DIR] [--work-tree=GIT_WORK_TREE] [-C DIR|--chdir=DIR] [--help] COMMAND [ARGS]";
 
 const char git_more_info_string[] =
 	"See 'git help COMMAND' for more information on a specific command.";
@@ -115,6 +115,23 @@ static int handle_options(const char*** argv, int* argc, int* envchanged)
 			setenv(GIT_DIR_ENVIRONMENT, getcwd(git_dir, sizeof(git_dir)), 0);
 			if (envchanged)
 				*envchanged = 1;
+		} else if (!strcmp(cmd, "-C") || !strcmp(cmd, "--chdir")) {
+			if (*argc < 2) {
+				fprintf(stderr, "No directory given for --chdir or -C.\n" );
+				usage(git_usage_string);
+			}
+			if (chdir((*argv)[1])) {
+				fprintf(stderr, "Cannot change directory to %s: %s\n", (*argv)[1], strerror(errno));
+				usage(git_usage_string);
+			}
+			(*argv)++;
+			(*argc)--;
+			handled++;
+		} else if (!prefixcmp(cmd,"--chdir=")) {
+			if (chdir(cmd+8)) {
+				fprintf(stderr, "Cannot change directory to %s: %s\n", cmd+8, strerror(errno));				     
+				usage(git_usage_string);
+			}
 		} else {
 			fprintf(stderr, "Unknown option: %s\n", cmd);
 			usage(git_usage_string);

-- 
1.6.0.1

Jeff King· Oct 19, 2008, 21:02 UTC · re: Maciej Pasternacki · lore

Re: [PATCH v2] Add command line option --chdir/-C to allow setting git process work directory.

On Sun, Oct 19, 2008 at 09:18:19AM -0700, Maciej Pasternacki wrote:

Show 5 quoted lines

> When "git pull" is ran outside of work tree, it is unable to update work tree
> with pulled changes; specifying --git-dir and --work-tree does not help here
> because "cd_to_toplevel" call in git-pull occurs after "require_work_tree";
> changing order may break the commend if there is no working tree.  Some more
> commands behave in a similar way.

I took a closer look at this. I'm not sure that there is actually a problem with moving the cd_to_toplevel before require_work_tree. cd_to_toplevel makes sure there is actually something to cdup to. In my test without a work-tree, "git rev-parse --show-cdup" simply printed nothing, causing no "cd" to occur.

Moreover, git-pull is not the only script with this problem. There are quite a few with

  require_work_tree
  cd_to_toplevel

which will break in the same way with --work-tree. And there are even more with just require_work_tree that don't cd_to_toplevel at all. So I suspect that --work-tree is largely broken in our scripts and nobody has actually tried it.

So:

  1. I think we can fix this breakage by swapping the two.

  2. There is still breakage in other scripts, some of which may need
     quite in-depth fixes (e.g., git-bisect requires a work tree but
     does not chdir at all. For the require_work_tree test to work, it
     needs to be inside the work tree, and the script will need a
     careful looking over to see what ramifications that has).

  3. I think your -C option has some merit independent of this, since
     it allows you to chdir and still use the usual lookup rules (e.g.,
     see if it is bare vs a regular repository). But I don't feel
     strongly about it one way or the other.

-Peff

v2Add command line option --chdir/-C to allow setting git process work directory.