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 == 2) && !strcmp("-v", argv[1]))
  73                 eprint("slock-"VERSION", © 2006-2007 Anselm R. Garbe\n");
  74         else if(argc != 1)
  75                 eprint("usage: slock [-v]\n");
  76         pws = get_password();
  77         if(!(dpy = XOpenDisplay(0)))
  78                 eprint("slock: cannot open display\n");
  79         screen = DefaultScreen(dpy);
  80         root = RootWindow(dpy, screen);
  81
  82         /* init */
  83         wa.override_redirect = 1;
  84         wa.background_pixel = BlackPixel(dpy, screen);
  85         w = XCreateWindow(dpy, root, 0, 0, DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
  86                         0, DefaultDepth(dpy, screen), CopyFromParent,
  87                         DefaultVisual(dpy, screen), CWOverrideRedirect | CWBackPixel, &wa);
  88         XAllocNamedColor(dpy, DefaultColormap(dpy, screen), "black", &black, &dummy);
  89         pmap = XCreateBitmapFromData(dpy, w, curs, 8, 8);
  90         invisible = XCreatePixmapCursor(dpy, pmap, pmap, &black, &black, 0, 0);
  91         XDefineCursor(dpy, w, invisible);
  92         XMapRaised(dpy, w);
  93         for(len = 1000; len; len--) {
  94                 if(XGrabPointer(dpy, root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
  95                         GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
  96                         break;
  97                 usleep(1000);
  98         }
  99         if((running = running && (len > 0))) {
 100                 for(len = 1000; len; len--) {
 101                         if(XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
 102                                 == GrabSuccess)
 103                                 break;
 104                         usleep(1000);
 105                 }
 106                 running = (len > 0);
 107         }
 108         len = 0;
 109         XSync(dpy, False);
 110
 111         /* main event loop */
 112         while(running && !XNextEvent(dpy, &ev))
 113                 if(ev.type == KeyPress) {
 114                         buf[0] = 0;
 115                         num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
 116                         if(IsFunctionKey(ksym) || IsKeypadKey(ksym)
 117                                         || IsMiscFunctionKey(ksym) || IsPFKey(ksym)
 118                                         || IsPrivateKeypadKey(ksym))
 119                                 continue;
 120                         switch(ksym) {
 121                         case XK_Return:
 122                                 passwd[len] = 0;
 123                                 if((running = strcmp(crypt(passwd, pws), pws)) != 0)
 124                                         XBell(dpy, 100);
 125                                 len = 0;
 126                                 break;
 127                         case XK_Escape:
 128                                 len = 0;
 129                                 break;
 130                         case XK_BackSpace:
 131                                 if(len)
 132                                         --len;
 133                                 break;
 134                         default:
 135                                 if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 136                                         memcpy(passwd + len, buf, num);
 137                                         len += num;
 138                                 }
 139                                 break;
 140                         }
 141                 }
 142         XUngrabPointer(dpy, CurrentTime);
 143         XFreePixmap(dpy, pmap);
 144         XDestroyWindow(dpy, w);
 145         XCloseDisplay(dpy);
 146         return 0;
 147 }