/* See LICENSE file for license details. */
#define _XOPEN_SOURCE   500
#define LENGTH(X)       (sizeof X / sizeof X[0])
#if HAVE_SHADOW_H
#include <shadow.h>
#endif

#include <ctype.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <X11/extensions/Xrandr.h>
#ifdef XINERAMA
#include <X11/extensions/Xinerama.h>
#endif
#include <X11/keysym.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xft/Xft.h>

#include "arg.h"
#include "util.h"

char *argv0;

enum {
  BACKGROUND,
  INIT,
  INPUT,
  FAILED,
  NUMCOLS
};

#include "config.h"

struct lock {
  int screen;
  Window root, win;
  Pixmap pmap;
  unsigned long colors[NUMCOLS];
  unsigned int x, y;
  unsigned int xoff, yoff, mw, mh;
  Drawable drawable;
  GC gc;
  XRectangle rectangles[LENGTH(rectangles)];
};

struct xrandr {
  int active;
  int evbase;
  int errbase;
};

  static void
die(const char *errstr, ...)
{
  va_list ap;

  va_start(ap, errstr);
  vfprintf(stderr, errstr, ap);
  va_end(ap);
  exit(1);
}

#ifdef __linux__
#include <fcntl.h>
#include <linux/oom.h>

  static void
dontkillme(void)
{
  FILE *f;
  const char oomfile[] = "/proc/self/oom_score_adj";

  if (!(f = fopen(oomfile, "w"))) {
    if (errno == ENOENT)
      return;
    die("slock: fopen %s: %s\n", oomfile, strerror(errno));
  }
  fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
  if (fclose(f)) {
    if (errno == EACCES)
      die("slock: unable to disable OOM killer. "
          "Make sure to suid or sgid slock.\n");
    else
      die("slock: fclose %s: %s\n", oomfile, strerror(errno));
  }
}
#endif

  static const char *
gethash(void)
{
  const char *hash;
  struct passwd *pw;

  /* Check if the current user has a password entry */
  errno = 0;
  if (!(pw = getpwuid(getuid()))) {
    if (errno)
      die("slock: getpwuid: %s\n", strerror(errno));
    else
      die("slock: cannot retrieve password entry\n");
  }
  hash = pw->pw_passwd;

#if HAVE_SHADOW_H
  if (!strcmp(hash, "x")) {
    struct spwd *sp;
    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 (!strcmp(hash, "*")) {
#ifdef __OpenBSD__
    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
    die("slock: getpwuid: cannot retrieve shadow entry. "
        "Make sure to suid or sgid slock.\n");
#endif /* __OpenBSD__ */
  }
#endif /* HAVE_SHADOW_H */

  return hash;
}

  static void
resizerectangles(struct lock *lock)
{
  int i;

  for (i = 0; i < LENGTH(rectangles); i++){
    lock->rectangles[i].x = (rectangles[i].x * logosize)
      + lock->xoff + ((lock->mw) / 2) - (logow / 2 * logosize);
    lock->rectangles[i].y = (rectangles[i].y * logosize)
      + lock->yoff + ((lock->mh) / 2) - (logoh / 2 * logosize);
    lock->rectangles[i].width = rectangles[i].width * logosize;
    lock->rectangles[i].height = rectangles[i].height * logosize;
  }
}

  static void
drawlogo(Display *dpy, struct lock *lock, int color)
{
  XSetForeground(dpy, lock->gc, lock->colors[BACKGROUND]);
  XFillRectangle(dpy, lock->drawable, lock->gc, 0, 0, lock->x, lock->y);
  XSetForeground(dpy, lock->gc, lock->colors[color]);
  XFillRectangles(dpy, lock->drawable, lock->gc, lock->rectangles, LENGTH(rectangles));
  XCopyArea(dpy, lock->drawable, lock->win, lock->gc, 0, 0, lock->x, lock->y, 0, 0);
  XSync(dpy, False);
}

  static void
readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens,
    const char *hash)
{
  XRRScreenChangeNotifyEvent *rre;
  char buf[32], passwd[256], *inputhash;
  int num, screen, running, failure, oldc;
  unsigned int len, color;
  KeySym ksym;
  XEvent ev;

  len = 0;
  running = 1;
  failure = 0;
  oldc = INIT;

  while (running && !XNextEvent(dpy, &ev)) {
    if (ev.type == KeyPress) {
      explicit_bzero(&buf, sizeof(buf));
      num = XLookupString(&ev.xkey, buf, sizeof(buf), &ksym, 0);
      if (IsKeypadKey(ksym)) {
        if (ksym == XK_KP_Enter)
          ksym = XK_Return;
        else if (ksym >= XK_KP_0 && ksym <= XK_KP_9)
          ksym = (ksym - XK_KP_0) + XK_0;
      }
      if (IsFunctionKey(ksym) ||
          IsKeypadKey(ksym) ||
          IsMiscFunctionKey(ksym) ||
          IsPFKey(ksym) ||
          IsPrivateKeypadKey(ksym))
        continue;
      switch (ksym) {
        case XK_Return:
          passwd[len] = '\0';
          errno = 0;
          if (!(inputhash = crypt(passwd, hash)))
            fprintf(stderr, "slock: crypt: %s\n", strerror(errno));
          else
            running = !!strcmp(inputhash, hash);
          if (running) {
            XBell(dpy, 100);
            failure = 1;
          }
          explicit_bzero(&passwd, sizeof(passwd));
          len = 0;
          break;
        case XK_Escape:
          explicit_bzero(&passwd, sizeof(passwd));
          len = 0;
          break;
        case XK_BackSpace:
          if (len)
            passwd[--len] = '\0';
          break;
        default:
          if (num && !iscntrl((int)buf[0]) &&
              (len + num < sizeof(passwd))) {
            memcpy(passwd + len, buf, num);
            len += num;
          }
          break;
      }
      color = len ? INPUT : ((failure || failonclear) ? FAILED : INIT);
      if (running && oldc != color) {
        for (screen = 0; screen < nscreens; screen++) {
          drawlogo(dpy, locks[screen], color);
        }
        oldc = color;
      }
    } else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) {
      rre = (XRRScreenChangeNotifyEvent*)&ev;
      for (screen = 0; screen < nscreens; screen++) {
        if (locks[screen]->win == rre->window) {
          if (rre->rotation == RR_Rotate_90 ||
              rre->rotation == RR_Rotate_270)
            XResizeWindow(dpy, locks[screen]->win,
                rre->height, rre->width);
          else
            XResizeWindow(dpy, locks[screen]->win,
                rre->width, rre->height);
          XClearWindow(dpy, locks[screen]->win);
          break;
        }
      }
    } else {
      for (screen = 0; screen < nscreens; screen++)
        XRaiseWindow(dpy, locks[screen]->win);
    }
  }
}

  static struct lock *
lockscreen(Display *dpy, struct xrandr *rr, int screen)
{
  char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
  int i, ptgrab, kbgrab;
  struct lock *lock;
  XColor color, dummy;
  XSetWindowAttributes wa;
  Cursor invisible;
#ifdef XINERAMA
  XineramaScreenInfo *info;
  int n;
#endif

  if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock))))
    return NULL;

  lock->screen = screen;
  lock->root = RootWindow(dpy, lock->screen);

  for (i = 0; i < NUMCOLS; i++) {
    XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen),
        colorname[i], &color, &dummy);
    lock->colors[i] = color.pixel;
  }

  lock->x = DisplayWidth(dpy, lock->screen);
  lock->y = DisplayHeight(dpy, lock->screen);
#ifdef XINERAMA
  if ((info = XineramaQueryScreens(dpy, &n))) {
    lock->xoff = info[0].x_org;
    lock->yoff = info[0].y_org;
    lock->mw = info[0].width;
    lock->mh = info[0].height;
  } else
#endif
  {
    lock->xoff = lock->yoff = 0;
    lock->mw = lock->x;
    lock->mh = lock->y;
  }
  lock->drawable = XCreatePixmap(dpy, lock->root,
      lock->x, lock->y, DefaultDepth(dpy, screen));
  lock->gc = XCreateGC(dpy, lock->root, 0, NULL);
  XSetLineAttributes(dpy, lock->gc, 1, LineSolid, CapButt, JoinMiter);

  /* init */
  wa.override_redirect = 1;
  wa.background_pixel = lock->colors[BACKGROUND];
  lock->win = XCreateWindow(dpy, lock->root, 0, 0,
      lock->x, lock->y,
      0, DefaultDepth(dpy, lock->screen),
      CopyFromParent,
      DefaultVisual(dpy, lock->screen),
      CWOverrideRedirect | CWBackPixel, &wa);
  lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
  invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap,
      &color, &color, 0, 0);
  XDefineCursor(dpy, lock->win, invisible);

  resizerectangles(lock);

  /* Try to grab mouse pointer *and* keyboard for 600ms, else fail the lock */
  for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
    if (ptgrab != GrabSuccess) {
      ptgrab = XGrabPointer(dpy, lock->root, False,
          ButtonPressMask | ButtonReleaseMask |
          PointerMotionMask, GrabModeAsync,
          GrabModeAsync, None, invisible, CurrentTime);
    }
    if (kbgrab != GrabSuccess) {
      kbgrab = XGrabKeyboard(dpy, lock->root, True,
          GrabModeAsync, GrabModeAsync, CurrentTime);
    }

    /* input is grabbed: we can lock the screen */
    if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
      XMapRaised(dpy, lock->win);
      if (rr->active)
        XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);

      XSelectInput(dpy, lock->root, SubstructureNotifyMask);
      drawlogo(dpy, lock, INIT);
      return lock;
    }

    /* retry on AlreadyGrabbed but fail on other errors */
    if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) ||
        (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
      break;

    usleep(100000);
  }

  /* we couldn't grab all input: fail out */
  if (ptgrab != GrabSuccess)
    fprintf(stderr, "slock: unable to grab mouse pointer for screen %d\n",
        screen);
  if (kbgrab != GrabSuccess)
    fprintf(stderr, "slock: unable to grab keyboard for screen %d\n",
        screen);
  return NULL;
}

  static void
usage(void)
{
  die("usage: slock [-v] [cmd [arg ...]]\n");
}

int
main(int argc, char **argv) {
  struct xrandr rr;
  struct lock **locks;
  struct passwd *pwd;
  struct group *grp;
  uid_t duid;
  gid_t dgid;
  const char *hash;
  Display *dpy;
  int s, nlocks, nscreens;

  ARGBEGIN {
    case 'v':
      fprintf(stderr, "slock-"VERSION"\n");
      return 0;
    default:
      usage();
  } ARGEND

  /* validate drop-user and -group */
  errno = 0;
  if (!(pwd = getpwnam(user)))
    die("slock: getpwnam %s: %s\n", user,
        errno ? strerror(errno) : "user entry not found");
  duid = pwd->pw_uid;
  errno = 0;
  if (!(grp = getgrnam(group)))
    die("slock: getgrnam %s: %s\n", group,
        errno ? strerror(errno) : "group entry not found");
  dgid = grp->gr_gid;

#ifdef __linux__
  dontkillme();
#endif

  hash = gethash();
  errno = 0;
  if (!crypt("", hash))
    die("slock: crypt: %s\n", strerror(errno));

  if (!(dpy = XOpenDisplay(NULL)))
    die("slock: cannot open display\n");

  /* drop privileges */
  if (setgroups(0, NULL) < 0)
    die("slock: setgroups: %s\n", strerror(errno));
  if (setgid(dgid) < 0)
    die("slock: setgid: %s\n", strerror(errno));
  if (setuid(duid) < 0)
    die("slock: setuid: %s\n", strerror(errno));

  /* check for Xrandr support */
  rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase);

  /* get number of screens in display "dpy" and blank them */
  nscreens = ScreenCount(dpy);
  if (!(locks = calloc(nscreens, sizeof(struct lock *))))
    die("slock: out of memory\n");
  for (nlocks = 0, s = 0; s < nscreens; s++) {
    if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
      nlocks++;
    else
      break;
  }
  XSync(dpy, 0);

  /* did we manage to lock everything? */
  if (nlocks != nscreens)
    return 1;

  /* run post-lock command */
  if (argc > 0) {
    switch (fork()) {
      case -1:
        die("slock: fork failed: %s\n", strerror(errno));
      case 0:
        if (close(ConnectionNumber(dpy)) < 0)
          die("slock: close: %s\n", strerror(errno));
        execvp(argv[0], argv);
        fprintf(stderr, "slock: execvp %s: %s\n", argv[0], strerror(errno));
        _exit(1);
    }
  }

  /* everything is now blank. Wait for the correct password */
  readpw(dpy, &rr, locks, nscreens, hash);

  for (nlocks = 0, s = 0; s < nscreens; s++) {
    XFreePixmap(dpy, locks[s]->drawable);
    XFreeGC(dpy, locks[s]->gc);
  }

  XSync(dpy, 0);
  XCloseDisplay(dpy);
  return 0;
}
