Set critical env PATH + SHELL early

When running Finit under boothcartd (bootchart2 project) the PATH is
lost due to a bug.  This was a wakeup, so set critical variables in
main() early, before calling fs_init().

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/finit.c

@@ -39,6 +39,7 @@
 #include <sys/sysmacros.h>
 #endif
 #include <sys/prctl.h>
+#include <paths.h>
 #ifdef _LIBITE_LITE
 # include <libite/lite.h>
 #else
@@ -622,6 +623,15 @@ int main(int argc, char *argv[])
 		return EX_NOPERM;
 	}
 
+	/*
+	 * Sanity check critical environment variables.  We need PATH
+	 * and SHELL for early commands like mount in fs_init().
+	 */
+	if (!checkenv("PATH"))
+		setenv("PATH", _PATH_STDPATH, 1);
+	if (!checkenv("SHELL"))
+		setenv("SHELL", _PATH_BSHELL, 1);
+
 	/*
 	 * Need /dev, /proc, and /sys for console=, remount and cgroups
 	 */

src/helpers.h

@@ -82,6 +82,17 @@ pid_t   run_sh          (char *tty, int noclear, int nowait, struct rlimit rlimi
 pid_t   run_bg          (char *cmd, char *args[]);
 int     run_parts       (char *dir, char *cmd, const char *env[], int progress, int sysv);
 
+
+static inline int checkenv(const char *env)
+{
+	const char *val = getenv(env);
+
+	if (!val || !val[0])
+		return 0;
+
+	return 1;
+}
+
 static inline int dprint(int fd, const char *s, size_t len)
 {
 	size_t loop = 3;