Simplify the meaning of %s

The rules governing %s where just too complicated. First of
all, looking at $SHELL is dangerous. For systemd --system,
it usually wouldn't be set. But it could be set if the admin
first started a debug shell, let's say /sbin/sash, and then
launched systemd from it. This shouldn't influence how daemons
are started later on, so is better ignored. Similar reasoning
holds for session mode. Some shells set $SHELL, while other
set it only when it wasn't set previously (e.g. zsh). This
results in fragility that is better avoided by ignoring $SHELL
totally.

With $SHELL out of the way, simplify things by saying that
%s==/bin/sh for root, and the configured shell otherwise.
get_shell() is the only caller, so it can be inlined.

Fixes one issue seen with 'make check'.

2 files changed, 0 insertions, 48 deletions

diff --git a/src/shared/util.c b/src/shared/util.c
index 03d6f00622..0444cf4456 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -5246,53 +5246,6 @@ int get_home_dir(char **_h) {
         return 0;
 }
 
-int get_shell(char **_sh) {
-        char *sh;
-        const char *e;
-        uid_t u;
-        struct passwd *p;
-
-        assert(_sh);
-
-        /* Take the user specified one */
-        e = getenv("SHELL");
-        if (e) {
-                sh = strdup(e);
-                if (!sh)
-                        return -ENOMEM;
-
-                *_sh = sh;
-                return 0;
-        }
-
-        /* Hardcode home directory for root to avoid NSS */
-        u = getuid();
-        if (u == 0) {
-                sh = strdup("/bin/sh");
-                if (!sh)
-                        return -ENOMEM;
-
-                *_sh = sh;
-                return 0;
-        }
-
-        /* Check the database... */
-        errno = 0;
-        p = getpwuid(u);
-        if (!p)
-                return errno ? -errno : -ESRCH;
-
-        if (!path_is_absolute(p->pw_shell))
-                return -EINVAL;
-
-        sh = strdup(p->pw_shell);
-        if (!sh)
-                return -ENOMEM;
-
-        *_sh = sh;
-        return 0;
-}
-
 void fclosep(FILE **f) {
         if (*f)
                 fclose(*f);
diff --git a/src/shared/util.h b/src/shared/util.h
index 7a38421007..52c33238b1 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -519,7 +519,6 @@ bool in_initrd(void);
 
 void warn_melody(void);
 
-int get_shell(char **ret);
 int get_home_dir(char **ret);
 
 static inline void freep(void *p) {