slock.c

   1 /* © 2006-2007 Anselm R. Garbe <garbeam at gmail dot com>
   2  * See LICENSE file for license details. */
   3 #define _XOPEN_SOURCE 500
   4 #if HAVE_SHADOW_H
   5 #include <shadow.h>
   6 #endif
   7
   8 #include <ctype.h>
   9 #include <pwd.h>
  10 #include <stdarg.h>
  11 #include <stdlib.h>
  12 #include <stdio.h>
  13 #include <string.h>
  14 #include <unistd.h>
  15 #include <sys/types.h>
  16 #include <X11/keysym.h>
  17 #include <X11/Xlib.h>
  18 #include <X11/Xutil.h>
  19
  20 void
  21 eprint(const char *errstr, ...) {
  22         va_list ap;
  23
  24         va_start(ap, errstr);
  25         vfprintf(stderr, errstr, ap);
  26         va_end(ap);
  27         exit(EXIT_FAILURE);
  28 }
  29
  30 const char *
  31 get_password() { /* only run as root */
  32         const char *rval;
  33         struct passwd *pw;
  34
  35         if(geteuid() != 0)
  36                 eprint("slock: cannot retrieve password entry (make sure to suid slock)\n");
  37         pw = getpwuid(getuid());
  38         endpwent();
  39         rval =  pw->pw_passwd;
  40
  41 #if HAVE_SHADOW_H
  42         {
  43                 struct spwd *sp;
  44                 sp = getspnam(getenv("USER"));
  45                 endspent();
  46                 rval = sp->sp_pwdp;
  47         }
  48 #endif
  49         /* drop privileges */
  50         if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
  51                 eprint("slock: cannot drop privileges\n");
  52         return rval;
  53 }
  54
  55 int
  56 main(int argc, char **argv) {
  57         char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
  58         char buf[32], passwd[256];
  59         int num, screen;
  60         const char *pws;
  61         unsigned int len;
  62         Bool running = True;
  63         Cursor invisible;
  64         Display *dpy;
  65         KeySym ksym;
  66         Pixmap pmap;
  67         Window root, w;
  68         XColor black, dummy;
  69         XEvent ev;
  70         XSetWindowAttributes wa;
  71
  72         if((argc > 1) && !strncmp(argv[1], "-v", 3))
  73                 eprint("slock-"VERSION", © 2006-2007 Anselm R. Garbe, Sander van Dijk\n");
  74         pws = get_password();
  75         if(!(dpy = XOpenDisplay(0)))
  76                 eprint("slock: cannot open display\n");
  77         screen = DefaultScreen(dpy);
  78         root = RootWindow(dpy, screen);
  79
  80         /* init */
  81         wa.override_redirect = 1;
  82         wa.background_pixel = BlackPixel(dpy, screen);
  83         w = XCreateWindow(dpy, root, 0, 0, DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
  84                         0, DefaultDepth(dpy, screen), CopyFromParent,
  85                         DefaultVisual(dpy, screen), CWOverrideRedirect | CWBackPixel, &wa);
  86         XAllocNamedColor(dpy, DefaultColormap(dpy, screen), "black", &black, &dummy);
  87         pmap = XCreateBitmapFromData(dpy, w, curs, 8, 8);
  88         invisible = XCreatePixmapCursor(dpy, pmap, pmap, &black, &black, 0, 0);
  89         XDefineCursor(dpy, w, invisible);
  90         XMapRaised(dpy, w);
  91         for(len = 1000; len; len--) {
  92                 if(XGrabPointer(dpy, root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
  93                         GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
  94                         break;
  95                 usleep(1000);
  96         }
  97         if((running = running && (len > 0))) {
  98                 for(len = 1000; len; len--) {
  99                         if(XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
 100                                 == GrabSuccess)
 101                                 break;
 102                         usleep(1000);
 103                 }
 104                 running = (len > 0);
 105         }
 106         len = 0;
 107         XSync(dpy, False);
 108
 109         /* main event loop */
 110         while(running && !XNextEvent(dpy, &ev))
 111                 if(ev.type == KeyPress) {
 112                         buf[0] = 0;
 113                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 114                         if(IsFunctionKey(ksym) || IsKeypadKey(ksym)
 115                                         || IsMiscFunctionKey(ksym) || IsPFKey(ksym)
 116                                         || IsPrivateKeypadKey(ksym))
 117                                 continue;
 118                         switch(ksym) {
 119                         case XK_Return:
 120                                 passwd[len] = 0;
 121                                 if((running = strcmp(crypt(passwd, pws), pws)) != 0)
 122                                         XBell(dpy, 100);
 123                                 len = 0;
 124                                 break;
 125                         case XK_Escape:
 126                                 len = 0;
 127                                 break;
 128                         case XK_BackSpace:
 129                                 if(len)
 130                                         --len;
 131                                 break;
 132                         default:
 133                                 if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 134                                         memcpy(passwd + len, buf, num);
 135                                         len += num;
 136                                 }
 137                                 break;
 138                         }
 139                 }
 140         XUngrabPointer(dpy, CurrentTime);
 141         XFreePixmap(dpy, pmap);
 142         XDestroyWindow(dpy, w);
 143         XCloseDisplay(dpy);
 144         return 0;
 145 }