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	slock.c - slock - simple X display locker utility
	git clone git://git.suckless.org/slock
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	---
	slock.c (9755B)
	---
	1 /* See LICENSE file for license details. */
	2 #define _XOPEN_SOURCE 500
	3 #if HAVE_SHADOW_H
	4 #include <shadow.h>
	5 #endif
	6
	7 #include <ctype.h>
	8 #include <errno.h>
	9 #include <grp.h>
	10 #include <pwd.h>
	11 #include <stdarg.h>
	12 #include <stdlib.h>
	13 #include <stdio.h>
	14 #include <string.h>
	15 #include <unistd.h>
	16 #include <spawn.h>
	17 #include <sys/types.h>
	18 #include <X11/extensions/Xrandr.h>
	19 #include <X11/keysym.h>
	20 #include <X11/Xlib.h>
	21 #include <X11/Xutil.h>
	22
	23 #include "arg.h"
	24 #include "util.h"
	25
	26 char *argv0;
	27
	28 enum {
	29 INIT,
	30 INPUT,
	31 FAILED,
	32 NUMCOLS
	33 };
	34
	35 struct lock {
	36 int screen;
	37 Window root, win;
	38 Pixmap pmap;
	39 unsigned long colors[NUMCOLS];
	40 };
	41
	42 struct xrandr {
	43 int active;
	44 int evbase;
	45 int errbase;
	46 };
	47
	48 #include "config.h"
	49
	50 static void
	51 die(const char *errstr, ...)
	52 {
	53 va_list ap;
	54
	55 va_start(ap, errstr);
	56 vfprintf(stderr, errstr, ap);
	57 va_end(ap);
	58 exit(1);
	59 }
	60
	61 #ifdef __linux__
	62 #include <fcntl.h>
	63 #include <linux/oom.h>
	64
	65 static void
	66 dontkillme(void)
	67 {
	68 FILE *f;
	69 const char oomfile[] = "/proc/self/oom_score_adj";
	70
	71 if (!(f = fopen(oomfile, "w"))) {
	72 if (errno == ENOENT)
	73 return;
	74 die("slock: fopen %s: %s\n", oomfile, strerror(errno));
	75 }
	76 fprintf(f, "%d", OOM_SCORE_ADJ_MIN);
	77 if (fclose(f)) {
	78 if (errno == EACCES)
	79 die("slock: unable to disable OOM killer. "
	80 "Make sure to suid or sgid slock.\n");
	81 else
	82 die("slock: fclose %s: %s\n", oomfile, strerror(…
	83 }
	84 }
	85 #endif
	86
	87 static const char *
	88 gethash(void)
	89 {
	90 const char *hash;
	91 struct passwd *pw;
	92
	93 /* Check if the current user has a password entry */
	94 errno = 0;
	95 if (!(pw = getpwuid(getuid()))) {
	96 if (errno)
	97 die("slock: getpwuid: %s\n", strerror(errno));
	98 else
	99 die("slock: cannot retrieve password entry\n");
	100 }
	101 hash = pw->pw_passwd;
	102
	103 #if HAVE_SHADOW_H
	104 if (!strcmp(hash, "x")) {
	105 struct spwd *sp;
	106 if (!(sp = getspnam(pw->pw_name)))
	107 die("slock: getspnam: cannot retrieve shadow ent…
	108 "Make sure to suid or sgid slock.\n");
	109 hash = sp->sp_pwdp;
	110 }
	111 #else
	112 if (!strcmp(hash, "*")) {
	113 #ifdef __OpenBSD__
	114 if (!(pw = getpwuid_shadow(getuid())))
	115 die("slock: getpwnam_shadow: cannot retrieve sha…
	116 "Make sure to suid or sgid slock.\n");
	117 hash = pw->pw_passwd;
	118 #else
	119 die("slock: getpwuid: cannot retrieve shadow entry. "
	120 "Make sure to suid or sgid slock.\n");
	121 #endif /* __OpenBSD__ */
	122 }
	123 #endif /* HAVE_SHADOW_H */
	124
	125 return hash;
	126 }
	127
	128 static void
	129 readpw(Display dpy, struct xrandr rr, struct lock **locks, int nscreen…
	130 const char *hash)
	131 {
	132 XRRScreenChangeNotifyEvent *rre;
	133 char buf[32], passwd[256], *inputhash;
	134 int num, screen, running, failure, oldc;
	135 unsigned int len, color;
	136 KeySym ksym;
	137 XEvent ev;
	138
	139 len = 0;
	140 running = 1;
	141 failure = 0;
	142 oldc = INIT;
	143
	144 while (running && !XNextEvent(dpy, &ev)) {
	145 if (ev.type == KeyPress) {
	146 explicit_bzero(&buf, sizeof(buf));
	147 num = XLookupString(&ev.xkey, buf, sizeof(buf), …
	148 if (IsKeypadKey(ksym)) {
	149 if (ksym == XK_KP_Enter)
	150 ksym = XK_Return;
	151 else if (ksym >= XK_KP_0 && ksym <= XK_K…
	152 ksym = (ksym - XK_KP_0) + XK_0;
	153 }
	154 if (IsFunctionKey(ksym) \|\|
	155 IsKeypadKey(ksym) \|\|
	156 IsMiscFunctionKey(ksym) \|\|
	157 IsPFKey(ksym) \|\|
	158 IsPrivateKeypadKey(ksym))
	159 continue;
	160 switch (ksym) {
	161 case XK_Return:
	162 passwd[len] = '\0';
	163 errno = 0;
	164 if (!(inputhash = crypt(passwd, hash)))
	165 fprintf(stderr, "slock: crypt: %…
	166 else
	167 running = !!strcmp(inputhash, ha…
	168 if (running) {
	169 XBell(dpy, 100);
	170 failure = 1;
	171 }
	172 explicit_bzero(&passwd, sizeof(passwd));
	173 len = 0;
	174 break;
	175 case XK_Escape:
	176 explicit_bzero(&passwd, sizeof(passwd));
	177 len = 0;
	178 break;
	179 case XK_BackSpace:
	180 if (len)
	181 passwd[--len] = '\0';
	182 break;
	183 default:
	184 if (num && !iscntrl((int)buf[0]) &&
	185 (len + num < sizeof(passwd))) {
	186 memcpy(passwd + len, buf, num);
	187 len += num;
	188 } else if (buf[0] == '\025') { /* ctrl-u…
	189 explicit_bzero(&passwd, sizeof(p…
	190 len = 0;
	191 }
	192 break;
	193 }
	194 color = len ? INPUT : ((failure \|\| failonclear) …
	195 if (running && oldc != color) {
	196 for (screen = 0; screen < nscreens; scre…
	197 XSetWindowBackground(dpy,
	198 locks[scree…
	199 locks[scree…
	200 XClearWindow(dpy, locks[screen]-…
	201 }
	202 oldc = color;
	203 }
	204 } else if (rr->active && ev.type == rr->evbase + RRScree…
	205 rre = (XRRScreenChangeNotifyEvent*)&ev;
	206 for (screen = 0; screen < nscreens; screen++) {
	207 if (locks[screen]->win == rre->window) {
	208 if (rre->rotation == RR_Rotate_9…
	209 rre->rotation == RR_Rotate_2…
	210 XResizeWindow(dpy, locks…
	211 rre->heigh…
	212 else
	213 XResizeWindow(dpy, locks…
	214 rre->width…
	215 XClearWindow(dpy, locks[screen]-…
	216 break;
	217 }
	218 }
	219 } else {
	220 for (screen = 0; screen < nscreens; screen++)
	221 XRaiseWindow(dpy, locks[screen]->win);
	222 }
	223 }
	224 }
	225
	226 static struct lock *
	227 lockscreen(Display dpy, struct xrandr rr, int screen)
	228 {
	229 char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
	230 int i, ptgrab, kbgrab;
	231 struct lock *lock;
	232 XColor color, dummy;
	233 XSetWindowAttributes wa;
	234 Cursor invisible;
	235
	236 if (dpy == NULL \|\| screen < 0 \|\| !(lock = malloc(sizeof(struct l…
	237 return NULL;
	238
	239 lock->screen = screen;
	240 lock->root = RootWindow(dpy, lock->screen);
	241
	242 for (i = 0; i < NUMCOLS; i++) {
	243 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen),
	244 colorname[i], &color, &dummy);
	245 lock->colors[i] = color.pixel;
	246 }
	247
	248 /* init */
	249 wa.override_redirect = 1;
	250 wa.background_pixel = lock->colors[INIT];
	251 lock->win = XCreateWindow(dpy, lock->root, 0, 0,
	252 DisplayWidth(dpy, lock->screen),
	253 DisplayHeight(dpy, lock->screen),
	254 0, DefaultDepth(dpy, lock->screen),
	255 CopyFromParent,
	256 DefaultVisual(dpy, lock->screen),
	257 CWOverrideRedirect \| CWBackPixel, &wa);
	258 lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
	259 invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap,
	260 &color, &color, 0, 0);
	261 XDefineCursor(dpy, lock->win, invisible);
	262
	263 /* Try to grab mouse pointer and keyboard for 600ms, else fail…
	264 for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
	265 if (ptgrab != GrabSuccess) {
	266 ptgrab = XGrabPointer(dpy, lock->root, False,
	267 ButtonPressMask \| ButtonRe…
	268 PointerMotionMask, GrabMod…
	269 GrabModeAsync, None, invis…
	270 }
	271 if (kbgrab != GrabSuccess) {
	272 kbgrab = XGrabKeyboard(dpy, lock->root, True,
	273 GrabModeAsync, GrabModeAs…
	274 }
	275
	276 /* input is grabbed: we can lock the screen */
	277 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
	278 XMapRaised(dpy, lock->win);
	279 if (rr->active)
	280 XRRSelectInput(dpy, lock->win, RRScreenC…
	281
	282 XSelectInput(dpy, lock->root, SubstructureNotify…
	283 return lock;
	284 }
	285
	286 /* retry on AlreadyGrabbed but fail on other errors */
	287 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) …
	288 (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
	289 break;
	290
	291 usleep(100000);
	292 }
	293
	294 /* we couldn't grab all input: fail out */
	295 if (ptgrab != GrabSuccess)
	296 fprintf(stderr, "slock: unable to grab mouse pointer for…
	297 screen);
	298 if (kbgrab != GrabSuccess)
	299 fprintf(stderr, "slock: unable to grab keyboard for scre…
	300 screen);
	301 return NULL;
	302 }
	303
	304 static void
	305 usage(void)
	306 {
	307 die("usage: slock [-v] [cmd [arg ...]]\n");
	308 }
	309
	310 int
	311 main(int argc, char **argv) {
	312 struct xrandr rr;
	313 struct lock **locks;
	314 struct passwd *pwd;
	315 struct group *grp;
	316 uid_t duid;
	317 gid_t dgid;
	318 const char *hash;
	319 Display *dpy;
	320 int s, nlocks, nscreens;
	321
	322 ARGBEGIN {
	323 case 'v':
	324 puts("slock-"VERSION);
	325 return 0;
	326 default:
	327 usage();
	328 } ARGEND
	329
	330 /* validate drop-user and -group */
	331 errno = 0;
	332 if (!(pwd = getpwnam(user)))
	333 die("slock: getpwnam %s: %s\n", user,
	334 errno ? strerror(errno) : "user entry not found");
	335 duid = pwd->pw_uid;
	336 errno = 0;
	337 if (!(grp = getgrnam(group)))
	338 die("slock: getgrnam %s: %s\n", group,
	339 errno ? strerror(errno) : "group entry not found");
	340 dgid = grp->gr_gid;
	341
	342 #ifdef __linux__
	343 dontkillme();
	344 #endif
	345
	346 hash = gethash();
	347 errno = 0;
	348 if (!crypt("", hash))
	349 die("slock: crypt: %s\n", strerror(errno));
	350
	351 if (!(dpy = XOpenDisplay(NULL)))
	352 die("slock: cannot open display\n");
	353
	354 /* drop privileges */
	355 if (setgroups(0, NULL) < 0)
	356 die("slock: setgroups: %s\n", strerror(errno));
	357 if (setgid(dgid) < 0)
	358 die("slock: setgid: %s\n", strerror(errno));
	359 if (setuid(duid) < 0)
	360 die("slock: setuid: %s\n", strerror(errno));
	361
	362 /* check for Xrandr support */
	363 rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase);
	364
	365 /* get number of screens in display "dpy" and blank them */
	366 nscreens = ScreenCount(dpy);
	367 if (!(locks = calloc(nscreens, sizeof(struct lock *))))
	368 die("slock: out of memory\n");
	369 for (nlocks = 0, s = 0; s < nscreens; s++) {
	370 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
	371 nlocks++;
	372 else
	373 break;
	374 }
	375 XSync(dpy, 0);
	376
	377 /* did we manage to lock everything? */
	378 if (nlocks != nscreens)
	379 return 1;
	380
	381 /* run post-lock command */
	382 if (argc > 0) {
	383 pid_t pid;
	384 extern char **environ;
	385 int err = posix_spawnp(&pid, argv[0], NULL, NULL, argv, …
	386 if (err) {
	387 die("slock: failed to execute post-lock command:…
	388 argv[0], strerror(err));
	389 }
	390 }
	391
	392 /* everything is now blank. Wait for the correct password */
	393 readpw(dpy, &rr, locks, nscreens, hash);
	394
	395 return 0;
	396 }