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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 (9634B)
	---
	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 }
	189 break;
	190 }
	191 color = len ? INPUT : ((failure \|\| failonclear) …
	192 if (running && oldc != color) {
	193 for (screen = 0; screen < nscreens; scre…
	194 XSetWindowBackground(dpy,
	195 locks[scree…
	196 locks[scree…
	197 XClearWindow(dpy, locks[screen]-…
	198 }
	199 oldc = color;
	200 }
	201 } else if (rr->active && ev.type == rr->evbase + RRScree…
	202 rre = (XRRScreenChangeNotifyEvent*)&ev;
	203 for (screen = 0; screen < nscreens; screen++) {
	204 if (locks[screen]->win == rre->window) {
	205 if (rre->rotation == RR_Rotate_9…
	206 rre->rotation == RR_Rotate_2…
	207 XResizeWindow(dpy, locks…
	208 rre->heigh…
	209 else
	210 XResizeWindow(dpy, locks…
	211 rre->width…
	212 XClearWindow(dpy, locks[screen]-…
	213 break;
	214 }
	215 }
	216 } else {
	217 for (screen = 0; screen < nscreens; screen++)
	218 XRaiseWindow(dpy, locks[screen]->win);
	219 }
	220 }
	221 }
	222
	223 static struct lock *
	224 lockscreen(Display dpy, struct xrandr rr, int screen)
	225 {
	226 char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
	227 int i, ptgrab, kbgrab;
	228 struct lock *lock;
	229 XColor color, dummy;
	230 XSetWindowAttributes wa;
	231 Cursor invisible;
	232
	233 if (dpy == NULL \|\| screen < 0 \|\| !(lock = malloc(sizeof(struct l…
	234 return NULL;
	235
	236 lock->screen = screen;
	237 lock->root = RootWindow(dpy, lock->screen);
	238
	239 for (i = 0; i < NUMCOLS; i++) {
	240 XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen),
	241 colorname[i], &color, &dummy);
	242 lock->colors[i] = color.pixel;
	243 }
	244
	245 /* init */
	246 wa.override_redirect = 1;
	247 wa.background_pixel = lock->colors[INIT];
	248 lock->win = XCreateWindow(dpy, lock->root, 0, 0,
	249 DisplayWidth(dpy, lock->screen),
	250 DisplayHeight(dpy, lock->screen),
	251 0, DefaultDepth(dpy, lock->screen),
	252 CopyFromParent,
	253 DefaultVisual(dpy, lock->screen),
	254 CWOverrideRedirect \| CWBackPixel, &wa);
	255 lock->pmap = XCreateBitmapFromData(dpy, lock->win, curs, 8, 8);
	256 invisible = XCreatePixmapCursor(dpy, lock->pmap, lock->pmap,
	257 &color, &color, 0, 0);
	258 XDefineCursor(dpy, lock->win, invisible);
	259
	260 /* Try to grab mouse pointer and keyboard for 600ms, else fail…
	261 for (i = 0, ptgrab = kbgrab = -1; i < 6; i++) {
	262 if (ptgrab != GrabSuccess) {
	263 ptgrab = XGrabPointer(dpy, lock->root, False,
	264 ButtonPressMask \| ButtonRe…
	265 PointerMotionMask, GrabMod…
	266 GrabModeAsync, None, invis…
	267 }
	268 if (kbgrab != GrabSuccess) {
	269 kbgrab = XGrabKeyboard(dpy, lock->root, True,
	270 GrabModeAsync, GrabModeAs…
	271 }
	272
	273 /* input is grabbed: we can lock the screen */
	274 if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
	275 XMapRaised(dpy, lock->win);
	276 if (rr->active)
	277 XRRSelectInput(dpy, lock->win, RRScreenC…
	278
	279 XSelectInput(dpy, lock->root, SubstructureNotify…
	280 return lock;
	281 }
	282
	283 /* retry on AlreadyGrabbed but fail on other errors */
	284 if ((ptgrab != AlreadyGrabbed && ptgrab != GrabSuccess) …
	285 (kbgrab != AlreadyGrabbed && kbgrab != GrabSuccess))
	286 break;
	287
	288 usleep(100000);
	289 }
	290
	291 /* we couldn't grab all input: fail out */
	292 if (ptgrab != GrabSuccess)
	293 fprintf(stderr, "slock: unable to grab mouse pointer for…
	294 screen);
	295 if (kbgrab != GrabSuccess)
	296 fprintf(stderr, "slock: unable to grab keyboard for scre…
	297 screen);
	298 return NULL;
	299 }
	300
	301 static void
	302 usage(void)
	303 {
	304 die("usage: slock [-v] [cmd [arg ...]]\n");
	305 }
	306
	307 int
	308 main(int argc, char **argv) {
	309 struct xrandr rr;
	310 struct lock **locks;
	311 struct passwd *pwd;
	312 struct group *grp;
	313 uid_t duid;
	314 gid_t dgid;
	315 const char *hash;
	316 Display *dpy;
	317 int s, nlocks, nscreens;
	318
	319 ARGBEGIN {
	320 case 'v':
	321 puts("slock-"VERSION);
	322 return 0;
	323 default:
	324 usage();
	325 } ARGEND
	326
	327 /* validate drop-user and -group */
	328 errno = 0;
	329 if (!(pwd = getpwnam(user)))
	330 die("slock: getpwnam %s: %s\n", user,
	331 errno ? strerror(errno) : "user entry not found");
	332 duid = pwd->pw_uid;
	333 errno = 0;
	334 if (!(grp = getgrnam(group)))
	335 die("slock: getgrnam %s: %s\n", group,
	336 errno ? strerror(errno) : "group entry not found");
	337 dgid = grp->gr_gid;
	338
	339 #ifdef __linux__
	340 dontkillme();
	341 #endif
	342
	343 hash = gethash();
	344 errno = 0;
	345 if (!crypt("", hash))
	346 die("slock: crypt: %s\n", strerror(errno));
	347
	348 if (!(dpy = XOpenDisplay(NULL)))
	349 die("slock: cannot open display\n");
	350
	351 /* drop privileges */
	352 if (setgroups(0, NULL) < 0)
	353 die("slock: setgroups: %s\n", strerror(errno));
	354 if (setgid(dgid) < 0)
	355 die("slock: setgid: %s\n", strerror(errno));
	356 if (setuid(duid) < 0)
	357 die("slock: setuid: %s\n", strerror(errno));
	358
	359 /* check for Xrandr support */
	360 rr.active = XRRQueryExtension(dpy, &rr.evbase, &rr.errbase);
	361
	362 /* get number of screens in display "dpy" and blank them */
	363 nscreens = ScreenCount(dpy);
	364 if (!(locks = calloc(nscreens, sizeof(struct lock *))))
	365 die("slock: out of memory\n");
	366 for (nlocks = 0, s = 0; s < nscreens; s++) {
	367 if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
	368 nlocks++;
	369 else
	370 break;
	371 }
	372 XSync(dpy, 0);
	373
	374 /* did we manage to lock everything? */
	375 if (nlocks != nscreens)
	376 return 1;
	377
	378 /* run post-lock command */
	379 if (argc > 0) {
	380 pid_t pid;
	381 extern char **environ;
	382 int err = posix_spawnp(&pid, argv[0], NULL, NULL, argv, …
	383 if (err) {
	384 die("slock: failed to execute post-lock command:…
	385 argv[0], strerror(err));
	386 }
	387 }
	388
	389 /* everything is now blank. Wait for the correct password */
	390 readpw(dpy, &rr, locks, nscreens, hash);
	391
	392 return 0;
	393 }