fixed usage string

Calling them unconditionally can result in memory corruption.

.hgtags

@@ -6,3 +6,5 @@ bd24ea7fcca26b161225c464df23ecbfe85280e1 0.5
 dd226a81c09adfa86db232419b3000b7e406df68 0.6
 c4635bb35a4581261f0187b347d5e596dd390ca3 0.7
 c0eb8221ba49c6d10becc93c063c45196a3bb1ba 0.8
+1e8a77601cb9c872921bbfc47909d9339027b295 0.9
+05b949016e85da011c48783d6896de801d347bed 1.0

LICENSE

@@ -1,6 +1,7 @@
 MIT/X Consortium License
 
-© 2006-2008 Anselm R Garbe <garbeam at gmail dot com>
+© 2014 Dimitris Papastamos <sin@2f30.org>
+© 2006-2014 Anselm R Garbe <anselm@garbe.us>
 
 Permission is hereby granted, free of charge, to any person obtaining a
 copy of this software and associated documentation files (the "Software"),

Makefile

@@ -1,5 +1,5 @@
 # slock - simple screen locker
-# © 2006-2007 Anselm R. Garbe, Sander van Dijk
+# See LICENSE file for copyright and license details.
 
 include config.mk
 
@@ -18,7 +18,11 @@ options:
 	@echo CC $<
 	@${CC} -c ${CFLAGS} $<
 
-${OBJ}: config.mk
+${OBJ}: config.h config.mk
+
+config.h:
+	@echo creating $@ from config.def.h
+	@cp config.def.h $@
 
 slock: ${OBJ}
 	@echo CC -o $@
@@ -31,7 +35,7 @@ clean:
 dist: clean
 	@echo creating dist tarball
 	@mkdir -p slock-${VERSION}
-	@cp -R LICENSE Makefile README config.mk ${SRC} slock-${VERSION}
+	@cp -R LICENSE Makefile README config.def.h config.mk ${SRC} slock-${VERSION}
 	@tar -cf slock-${VERSION}.tar slock-${VERSION}
 	@gzip slock-${VERSION}.tar
 	@rm -rf slock-${VERSION}

config.def.h

@@ -0,0 +1,2 @@
+#define COLOR1 "black"
+#define COLOR2 "#005577"

config.mk

@@ -1,5 +1,5 @@
 # slock version
-VERSION = 0.9
+VERSION = 1.2
 
 # Customize below to fit your system
 

slock.c

@@ -1,3 +1,4 @@
+
 /* See LICENSE file for license details. */
 #define _XOPEN_SOURCE 500
 #if HAVE_SHADOW_H
@@ -5,6 +6,7 @@
 #endif
 
 #include <ctype.h>
+#include <errno.h>
 #include <pwd.h>
 #include <stdarg.h>
 #include <stdlib.h>
@@ -15,13 +17,25 @@
 #include <X11/keysym.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
-#include <X11/extensions/dpms.h>
 
 #if HAVE_BSD_AUTH
 #include <login_cap.h>
 #include <bsd_auth.h>
 #endif
 
+#include "config.h"
+
+typedef struct {
+	int screen;
+	Window root, win;
+	Pixmap pmap;
+	unsigned long colors[2];
+} Lock;
+
+static Lock **locks;
+static int nscreens;
+static Bool running = True;
+
 static void
 die(const char *errstr, ...) {
 	va_list ap;
@@ -32,103 +46,76 @@ die(const char *errstr, ...) {
 	exit(EXIT_FAILURE);
 }
 
+#ifdef __linux__
+#include <fcntl.h>
+
+static void
+dontkillme(void) {
+	int fd;
+
+	fd = open("/proc/self/oom_score_adj", O_WRONLY);
+	if (fd < 0 && errno == ENOENT)
+		return;
+	if (fd < 0 || write(fd, "-1000\n", 6) != 6 || close(fd) != 0)
+		die("cannot disable the out-of-memory killer for this process\n");
+}
+#endif
+
 #ifndef HAVE_BSD_AUTH
 static const char *
-get_password() { /* only run as root */
+getpw(void) { /* only run as root */
 	const char *rval;
 	struct passwd *pw;
 
-	if(geteuid() != 0)
-		die("slock: cannot retrieve password entry (make sure to suid slock)\n");
+	errno = 0;
 	pw = getpwuid(getuid());
-	endpwent();
+	if (!pw) {
+		if (errno)
+			die("slock: getpwuid: %s\n", strerror(errno));
+		else
+			die("slock: cannot retrieve password entry (make sure to suid or sgid slock)\n");
+	}
 	rval =  pw->pw_passwd;
 
 #if HAVE_SHADOW_H
-	{
+	if (rval[0] == 'x' && rval[1] == '\0') {
 		struct spwd *sp;
 		sp = getspnam(getenv("USER"));
-		endspent();
+		if(!sp)
+			die("slock: cannot retrieve shadow entry (make sure to suid or sgid slock)\n");
 		rval = sp->sp_pwdp;
 	}
 #endif
 
 	/* drop privileges */
-	if(setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0)
+	if (geteuid() == 0
+	   && ((getegid() != pw->pw_gid && setgid(pw->pw_gid) < 0) || setuid(pw->pw_uid) < 0))
 		die("slock: cannot drop privileges\n");
 	return rval;
 }
 #endif
 
-int
-main(int argc, char **argv) {
-	char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
+static void
+#ifdef HAVE_BSD_AUTH
+readpw(Display *dpy)
+#else
+readpw(Display *dpy, const char *pws)
+#endif
+{
 	char buf[32], passwd[256];
 	int num, screen;
-
-#ifndef HAVE_BSD_AUTH
-	const char *pws;
-#endif
-	unsigned int len;
-	Bool running = True;
-	Cursor invisible;
-	Display *dpy;
+	unsigned int len, llen;
 	KeySym ksym;
-	Pixmap pmap;
-	Window root, w;
-	XColor black, dummy;
 	XEvent ev;
-	XSetWindowAttributes wa;
 
-	if((argc == 2) && !strcmp("-v", argv[1]))
-		die("slock-"VERSION", © 2006-2008 Anselm R Garbe\n");
-	else if(argc != 1)
-		die("usage: slock [-v]\n");
+	len = llen = 0;
+	running = True;
 
-#ifndef HAVE_BSD_AUTH
-	pws = get_password();
-#endif
-
-	if(!(dpy = XOpenDisplay(0)))
-		die("slock: cannot open display\n");
-	screen = DefaultScreen(dpy);
-	root = RootWindow(dpy, screen);
-
-	/* init */
-	wa.override_redirect = 1;
-	wa.background_pixel = BlackPixel(dpy, screen);
-	w = XCreateWindow(dpy, root, 0, 0, DisplayWidth(dpy, screen), DisplayHeight(dpy, screen),
-			0, DefaultDepth(dpy, screen), CopyFromParent,
-			DefaultVisual(dpy, screen), CWOverrideRedirect | CWBackPixel, &wa);
-	XAllocNamedColor(dpy, DefaultColormap(dpy, screen), "black", &black, &dummy);
-	pmap = XCreateBitmapFromData(dpy, w, curs, 8, 8);
-	invisible = XCreatePixmapCursor(dpy, pmap, pmap, &black, &black, 0, 0);
-	XDefineCursor(dpy, w, invisible);
-	XMapRaised(dpy, w);
-	for(len = 1000; len; len--) {
-		if(XGrabPointer(dpy, root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
-			GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
-			break;
-		usleep(1000);
-	}
-	if((running = running && (len > 0))) {
-		for(len = 1000; len; len--) {
-			if(XGrabKeyboard(dpy, root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
-				== GrabSuccess)
-				break;
-			usleep(1000);
-		}
-		running = (len > 0);
-	}
-	len = 0;
-	XSync(dpy, False);
-
-	/* main event loop */
+	/* As "slock" stands for "Simple X display locker", the DPMS settings
+	 * had been removed and you can set it with "xset" or some other
+	 * utility. This way the user can easily set a customized DPMS
+	 * timeout. */
 	while(running && !XNextEvent(dpy, &ev)) {
-		if(len == 0 && DPMSCapable(dpy)) {
-			DPMSEnable(dpy);
-			DPMSForceLevel(dpy, DPMSModeOff);
-		}
 		if(ev.type == KeyPress) {
 			buf[0] = 0;
 			num = XLookupString(&ev.xkey, buf, sizeof buf, &ksym, 0);
@@ -148,9 +135,9 @@ main(int argc, char **argv) {
 #ifdef HAVE_BSD_AUTH
 				running = !auth_userokay(getlogin(), NULL, "auth-xlock", passwd);
 #else
-				running = strcmp(crypt(passwd, pws), pws);
+				running = !!strcmp(crypt(passwd, pws), pws);
 #endif
-				if (running != 0)
+				if(running)
 					XBell(dpy, 100);
 				len = 0;
 				break;
@@ -162,17 +149,167 @@ main(int argc, char **argv) {
 					--len;
 				break;
 			default:
-				if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) { 
+				if(num && !iscntrl((int) buf[0]) && (len + num < sizeof passwd)) {
 					memcpy(passwd + len, buf, num);
 					len += num;
 				}
 				break;
 			}
+			if(llen == 0 && len != 0) {
+				for(screen = 0; screen < nscreens; screen++) {
+					XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[1]);
+					XClearWindow(dpy, locks[screen]->win);
+				}
+			} else if(llen != 0 && len == 0) {
+				for(screen = 0; screen < nscreens; screen++) {
+					XSetWindowBackground(dpy, locks[screen]->win, locks[screen]->colors[0]);
+					XClearWindow(dpy, locks[screen]->win);
+				}
+			}
+			llen = len;
+		}
+		else for(screen = 0; screen < nscreens; screen++)
+			XRaiseWindow(dpy, locks[screen]->win);
+	}
+}
+
+static void
+unlockscreen(Display *dpy, Lock *lock) {
+	if(dpy == NULL || lock == NULL)
+		return;
+
+	XUngrabPointer(dpy, CurrentTime);
+	XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, 2, 0);
+	XFreePixmap(dpy, lock->pmap);
+	XDestroyWindow(dpy, lock->win);
+
+	free(lock);
+}
+
+static Lock *
+lockscreen(Display *dpy, int screen) {
+	char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
+	unsigned int len;
+	Lock *lock;
+	XColor color, dummy;
+	XSetWindowAttributes wa;
+	Cursor invisible;
+
+	if(dpy == NULL || screen < 0)
+		return NULL;
+
+	lock = malloc(sizeof(Lock));
+	if(lock == NULL)
+		return NULL;
+
+	lock->screen = screen;
+
+	lock->root = RootWindow(dpy, lock->screen);
+
+	/* init */
+	wa.override_redirect = 1;
+	wa.background_pixel = BlackPixel(dpy, lock->screen);
+	lock->win = XCreateWindow(dpy, lock->root, 0, 0, DisplayWidth(dpy, lock->screen), DisplayHeight(dpy, lock->screen),
+			0, DefaultDepth(dpy, lock->screen), CopyFromParent,
+			DefaultVisual(dpy, lock->screen), CWOverrideRedirect | CWBackPixel, &wa);
+	XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR2, &color, &dummy);
+	lock->colors[1] = color.pixel;
+	XAllocNamedColor(dpy, DefaultColormap(dpy, lock->screen), COLOR1, &color, &dummy);
+	lock->colors[0] = color.pixel;
+	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);
+	XMapRaised(dpy, lock->win);
+	for(len = 1000; len; len--) {
+		if(XGrabPointer(dpy, lock->root, False, ButtonPressMask | ButtonReleaseMask | PointerMotionMask,
+			GrabModeAsync, GrabModeAsync, None, invisible, CurrentTime) == GrabSuccess)
+			break;
+		usleep(1000);
+	}
+	if(running && (len > 0)) {
+		for(len = 1000; len; len--) {
+			if(XGrabKeyboard(dpy, lock->root, True, GrabModeAsync, GrabModeAsync, CurrentTime)
+				== GrabSuccess)
+				break;
+			usleep(1000);
 		}
 	}
-	XUngrabPointer(dpy, CurrentTime);
-	XFreePixmap(dpy, pmap);
-	XDestroyWindow(dpy, w);
+
+	running &= (len > 0);
+	if(!running) {
+		unlockscreen(dpy, lock);
+		lock = NULL;
+	}
+	else 
+		XSelectInput(dpy, lock->root, SubstructureNotifyMask);
+
+	return lock;
+}
+
+static void
+usage(void) {
+	fprintf(stderr, "usage: slock [-v]\n");
+	exit(EXIT_FAILURE);
+}
+
+int
+main(int argc, char **argv) {
+#ifndef HAVE_BSD_AUTH
+	const char *pws;
+#endif
+	Display *dpy;
+	int screen;
+
+	if((argc == 2) && !strcmp("-v", argv[1]))
+		die("slock-%s, © 2006-2014 slock engineers\n", VERSION);
+	else if(argc != 1)
+		usage();
+
+#ifdef __linux__
+	dontkillme();
+#endif
+
+	if(!getpwuid(getuid()))
+		die("slock: no passwd entry for you\n");
+
+#ifndef HAVE_BSD_AUTH
+	pws = getpw();
+#endif
+
+	if(!(dpy = XOpenDisplay(0)))
+		die("slock: cannot open display\n");
+	/* Get the number of screens in display "dpy" and blank them all. */
+	nscreens = ScreenCount(dpy);
+	locks = malloc(sizeof(Lock *) * nscreens);
+	if(locks == NULL)
+		die("slock: malloc: %s\n", strerror(errno));
+	int nlocks = 0;
+	for(screen = 0; screen < nscreens; screen++) {
+		if ( (locks[screen] = lockscreen(dpy, screen)) != NULL)
+			nlocks++;
+	}
+	XSync(dpy, False);
+
+	/* Did we actually manage to lock something? */
+	if (nlocks == 0) { // nothing to protect
+		free(locks);
+		XCloseDisplay(dpy);
+		return 1;
+	}
+
+	/* Everything is now blank. Now wait for the correct password. */
+#ifdef HAVE_BSD_AUTH
+	readpw(dpy);
+#else
+	readpw(dpy, pws);
+#endif
+
+	/* Password ok, unlock everything and quit. */
+	for(screen = 0; screen < nscreens; screen++)
+		unlockscreen(dpy, locks[screen]);
+
+	free(locks);
 	XCloseDisplay(dpy);
+
 	return 0;
 }