slock.c

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