applied Robert Schneider's Linux suggestions, also bumped version and updated LICENSE...

[slock.git] / slock.c

diff --git a/slock.c b/slock.c
index 154a0918bee1b272ddd911d2c3736d08ef2b99ca..467937cee0c0474ea98b5bfb1bf7c2c9b2a9cbd4 100644 (file)
--- a/slock.c
+++ b/slock.c
@@ -44,6 +44,21 @@ die(const char *errstr, ...) {
        exit(EXIT_FAILURE);
 }
 
+#ifdef __linux__
+#include <fcntl.h>
+
+static void
+dontkillme(void) {
+       int fd;
+
+       fd = open("/proc/self/oom_score_adj", O_WRONLY);
+       if (fd < 0 && errno == ENOENT)
+               return;
+       if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
+               die("cannot disable the out-of-memory killer for this process\n");
+}
+#endif
+
 #ifndef HAVE_BSD_AUTH
 static const char *
 getpw(void) { /* only run as root */
@@ -52,7 +67,7 @@ getpw(void) { /* only run as root */
 
        pw = getpwuid(getuid());
        if(!pw)
-               die("slock: cannot retrieve password entry (make sure to suid or sgid slock)");
+               die("slock: cannot retrieve password entry (make sure to suid or sgid slock)\n");
        endpwent();
        rval =  pw->pw_passwd;
 
@@ -68,8 +83,9 @@ getpw(void) { /* only run as root */
 #endif
 
        /* drop privileges */
-       if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
-               die("slock: cannot drop privileges");
+       if (geteuid() == 0
+          && ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
+               die("slock: cannot drop privileges\n");
        return rval;
 }
 #endif
@@ -114,9 +130,9 @@ readpw(Display *dpy, const char *pws)
 #ifdef HAVE_BSD_AUTH
                                running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 #else
-                               running = strcmp(crypt(passwd, pws), pws);
+                               running = !!strcmp(crypt(passwd, pws), pws);
 #endif
-                               if(running != False)
+                               if(running)
                                        XBell(dpy, 100);
                                len = 0;
                                break;
@@ -244,20 +260,24 @@ main(int argc, char **argv) {
        else if(argc != 1)
                usage();
 
+#ifdef __linux__
+       dontkillme();
+#endif
+
        if(!getpwuid(getuid()))
-               die("slock: no passwd entry for you");
+               die("slock: no passwd entry for you\n");
 
 #ifndef HAVE_BSD_AUTH
        pws = getpw();
 #endif
 
        if(!(dpy = XOpenDisplay(0)))
-               die("slock: cannot open display");
+               die("slock: cannot open display\n");
        /* Get the number of screens in display "dpy" and blank them all. */
        nscreens = ScreenCount(dpy);
        locks = malloc(sizeof(Lock *) * nscreens);
        if(locks == NULL)
-               die("slock: malloc: %s", strerror(errno));
+               die("slock: malloc: %s\n", strerror(errno));
        int nlocks = 0;
        for(screen = 0; screen < nscreens; screen++) {
                if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)