[PATCH] set bash env variables before running scripts

[Andrew Gregory]

Bash sources user configuration files under a number of conditions that
can cause issues with scripts when bash is used as the scriptlet shell.

Bash assumes it's being run under rsh/ssh if stdin is connected to a
socket and sources the user bashrc unless the environment variable
$SHLVL is >= 2.  Commit 6a4c6a02de9b45abe4c0f78c4f5d14d92d3359d6
switched from pipes to sockets when communicating with child processes
to work around SIGPIPE issues.  Normally $SHLVL would be inherited from
the shell running pacman, but operations involving scriptlets are
generally run with sudo which does not let the $SHLVL variable through
unless specifically configured to.

Similarly $BASH_ENV can cause bash to source user-specified configuration
files if set.

https://lists.gnu.org/archive/html/help-bash/2022-02/msg00082.html

Signed-off-by: Andrew Gregory <andrew.gregory.8 at gmail.com>
---

Not entirely sure we should actually be unsetting $BASH_ENV, but Chet
recommended it.

 lib/libalpm/util.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c
index 06e0fe7f2..7340ce832 100644
--- a/lib/libalpm/util.c
+++ b/lib/libalpm/util.c
@@ -659,6 +659,11 @@ int _alpm_run_chroot(alpm_handle_t *handle, const char *cmd, char *const argv[],
 					"/", strerror(errno));
 			exit(1);
 		}
+		/* bash thinks it's being run under rsh/ssh if stdin is a socket and
+		 * sources ~/.bashrc unles SHLVL is > 1 */
+		setenv("SHLVL", "1", 0);
+		/* bash sources $BASH_ENV when run non-interactively */
+		unsetenv("BASH_ENV");
 		umask(0022);
 		_alpm_reset_signals();
 		execv(cmd, argv);
-- 
2.35.1