Stop using $USER for shadow entries

This was extremely bad practice, effectively making the program behave
different depending on which architecture you are running it on.

OpenBSD offers getpwuid_shadow, but there is no getspuid for getspnam,
so we resort to using the pw_name entry in the struct passwd we filled
earlier.

This prevents slock from crashing when $USER is empty (easy to do). If
you want to run slock as a different user, don't use

	$ USER="tom" slock

but doas or sudo which were designed for this purpose.

diff --git a/slock.c b/slock.c
index f799174..6dedc69 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -103,14 +103,14 @@ gethash(void)
 #if HAVE_SHADOW_H
        if (hash[0] == 'x' && hash[1] == '\0') {
                struct spwd *sp;
-               if (!(sp = getspnam(getenv("USER"))))
+               if (!(sp = getspnam(pw->pw_name)))
                        die("slock: getspnam: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
                hash = sp->sp_pwdp;
        }
 #else
        if (hash[0] == '*' && hash[1] == '\0') {
 #ifdef __OpenBSD__
-               if (!(pw = getpwnam_shadow(getenv("USER"))))
+               if (!(pw = getpwuid_shadow(getuid())))
                        die("slock: getpwnam_shadow: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
                hash = pw->pw_passwd;
 #else