/* 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 <math.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 <X11/Xresource.h>
#include <security/pam_appl.h>
#include <security/pam_misc.h>

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

char *argv0;
static int pam_conv(int num_msg, const struct pam_message **msg, struct pam_response **resp, void *appdata_ptr);
struct pam_conv pamc = {pam_conv, NULL};
char passwd[256];

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

/* Xresources preferences */
enum resource_type {
	STRING = 0,
	INTEGER = 1,
	FLOAT = 2
};

typedef struct {
	char *name;
	enum resource_type type;
	void *dst;
} ResourcePref;

#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);
}

static int
pam_conv(int num_msg, const struct pam_message **msg,
		struct pam_response **resp, void *appdata_ptr)
{
	int retval = PAM_CONV_ERR;
	for(int i=0; i<num_msg; i++) {
		if (msg[i]->msg_style == PAM_PROMPT_ECHO_OFF &&
				strncmp(msg[i]->msg, "Password: ", 10) == 0) {
			struct pam_response *resp_msg = malloc(sizeof(struct pam_response));
			if (!resp_msg)
				die("malloc failed\n");
			char *password = malloc(strlen(passwd) + 1);
			if (!password)
				die("malloc failed\n");
			memset(password, 0, strlen(passwd) + 1);
			strcpy(password, passwd);
			resp_msg->resp_retcode = 0;
			resp_msg->resp = password;
			resp[i] = resp_msg;
			retval = PAM_SUCCESS;
		}
	}
	return retval;
}

#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 */

	/* pam, store user name */
	hash = pw->pw_name;
	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];
	int num, screen, running, failure, oldc, retval;
	unsigned int len, color;
	KeySym ksym;
	XEvent ev;
	pam_handle_t *pamh;

	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;
				retval = pam_start(pam_service, hash, &pamc, &pamh);
				for (screen = 0; screen < nscreens; screen++) {
					drawlogo(dpy, locks[screen], PAM);
					XRaiseWindow(dpy, locks[screen]->win);
				}
				XSync(dpy, False);

				if (retval == PAM_SUCCESS)
					retval = pam_authenticate(pamh, 0);
				if (retval == PAM_SUCCESS)
					retval = pam_acct_mgmt(pamh, 0);

				running = 1;
				if (retval == PAM_SUCCESS)
					running = 0;
				else
					fprintf(stderr, "slock: %s\n", pam_strerror(pamh, retval));
				pam_end(pamh, retval);
				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;
}

int
resource_load(XrmDatabase db, char *name, enum resource_type rtype, void *dst)
{
	char **sdst = dst;
	int *idst = dst;
	float *fdst = dst;

	char fullname[256];
	char fullclass[256];
	char *type;
	XrmValue ret;

	snprintf(fullname, sizeof(fullname), "%s.%s", "slock", name);
	snprintf(fullclass, sizeof(fullclass), "%s.%s", "Slock", name);
	fullname[sizeof(fullname) - 1] = fullclass[sizeof(fullclass) - 1] = '\0';

	XrmGetResource(db, fullname, fullclass, &type, &ret);
	if (ret.addr == NULL || strncmp("String", type, 64))
		return 1;

	switch (rtype) {
	case STRING:
		*sdst = ret.addr;
		break;
	case INTEGER:
		*idst = strtoul(ret.addr, NULL, 10);
		break;
	case FLOAT:
		*fdst = strtof(ret.addr, NULL);
		break;
	}
	return 0;
}

void
config_init(Display *dpy)
{
	char *resm;
	XrmDatabase db;
	ResourcePref *p;

	XrmInitialize();
	resm = XResourceManagerString(dpy);
	if (!resm)
		return;

	db = XrmGetStringDatabase(resm);
	for (p = resources; p < resources + LEN(resources); p++)
		resource_load(db, p->name, p->type, p->dst);
}

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

	/* the contents of hash are used to transport the current user name */
	hash = gethash();
	errno = 0;

	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));

	config_init(dpy);

	/* 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);
		}
	}

  // Run a post system-lock command:
  system(cmd);

	/* 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;
}