[PATCH 1/2] run-command.c: Define SHELL_PATH macro for use in prepare_shell_cmd

The shell spawned in run-command.c:prepare_shell_cmd was hard coded to
'sh'.  Instead, make this a macro named SHELL_PATH so that it can be
overridden by the build system.  Use 'sh' as the default to preserve
original behaviour and ensure that a value is always set.

This avoids a situation where some commands were spawned using a
different shell than the one configured at build time.  Previously, it
was possible for things to be executed by a non-POSIX shell depending
on the user's PATH.

Signed-off-by: Ben Walton <redacted>
---
 run-command.c |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)

diff --git a/run-command.c b/run-command.c
index 1db8abf..f005a31 100644
--- a/run-command.c
+++ b/run-command.c

@@ -4,6 +4,10 @@
 #include "sigchain.h"
 #include "argv-array.h"
 
+#ifndef SHELL_PATH
+# define SHELL_PATH "sh"
+#endif
+
 struct child_to_clean {
 	pid_t pid;
 	struct child_to_clean *next;

@@ -90,7 +94,7 @@ static const char **prepare_shell_cmd(const char **argv)
 		die("BUG: shell command is empty");
 
 	if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
-		nargv[nargc++] = "sh";
+		nargv[nargc++] = SHELL_PATH;
 		nargv[nargc++] = "-c";
 
 		if (argc < 2)

-- 
1.7.5.4