Exec git programs without using PATH.

The git suite may not be in PATH (and thus programs such as
git-send-pack could not exec git-rev-list).  Thus there is a need for
logic that will locate these programs.  Modifying PATH is not
desirable as it result in behavior differing from the user's
intentions, as we may end up prepending "/usr/bin" to PATH.

- git C programs will use exec*_git_cmd() APIs to exec sub-commands.
- exec*_git_cmd() will execute a git program by searching for it in
  the following directories:
	1. --exec-path (as used by "git")
	2. The GIT_EXEC_PATH environment variable.
	3. $(gitexecdir) as set in Makefile (default value $(bindir)).
- git wrapper will modify PATH as before to enable shell scripts to
  invoke "git-foo" commands.

Ideally, shell scripts should use the git wrapper to become independent
of PATH, and then modifying PATH will not be necessary.

[jc: with minor updates after a brief review.]

Signed-off-by: Michal Ostrowski <mostrows@watson.ibm.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

1 files changed, 10 insertions, 0 deletions

diff --git a/exec_cmd.h b/exec_cmd.h
new file mode 100644
index 0000000000..5150ee29f7
--- /dev/null
+++ b/exec_cmd.h
@@ -0,0 +1,10 @@
+#ifndef __GIT_EXEC_CMD_H_
+#define __GIT_EXEC_CMD_H_
+
+extern void git_set_exec_path(const char *exec_path);
+extern const char* git_exec_path(void);
+extern int execv_git_cmd(char **argv); /* NULL terminated */
+extern int execl_git_cmd(char *cmd, ...);
+
+
+#endif /* __GIT_EXEC_CMD_H_ */