Remove cleanup and deglobalize and rework data structures

The cleanup removal is a joint-venture with Markus. We assume the X server does
the cleanup, so we don't need it. The idea is that the fds are closed at exit
and thus already indicate to the X server that the client has quit. Analogously
the same applies to freeing memory sections previously allocated for the X
server.

We love XXXXXL burgers and therefore removed
XUngrabPointer
XUngrabKeyboard
XFreeColors
XFreePixmap
XDestroyWindow
Lines of Code.

For a project like slock there is no need to carry around global state. By
moving the three structures to main() it is now clear which functions modify
which state, greatly improving the readability of the code, especially given
slock is a suid program.

slock.c

@@ -33,18 +33,18 @@ enum {
 
 #include "config.h"
 
-typedef struct {
+struct lock {
 	int screen;
 	Window root, win;
 	Pixmap pmap;
 	unsigned long colors[NUMCOLS];
-} Lock;
+};
 
-static Lock **locks;
+struct xrandr {
-static int nscreens;
+	int active;
-static Bool rr;
+	int evbase;
-static int rrevbase;
+	int errbase;
-static int rrerrbase;
+};
 
 static void
 die(const char *errstr, ...)
@@ -123,7 +123,8 @@ getpw(void)
 }
 
 static void
-readpw(Display *dpy, const char *pws)
+readpw(Display *dpy, struct xrandr *rr, struct lock **locks, int nscreens,
+       const char *pws)
 {
 	char buf[32], passwd[256], *encrypted;
 	int num, screen, running, failure;
@@ -194,7 +195,7 @@ readpw(Display *dpy, const char *pws)
 				}
 				oldc = color;
 			}
-		} else if (rr && ev.type == rrevbase + RRScreenChangeNotify) {
+		} else if (rr->active && ev.type == rr->evbase + RRScreenChangeNotify) {
 			XRRScreenChangeNotifyEvent *rre = (XRRScreenChangeNotifyEvent*)&ev;
 			for (screen = 0; screen < nscreens; screen++) {
 				if (locks[screen]->win == rre->window) {
@@ -207,44 +208,17 @@ readpw(Display *dpy, const char *pws)
 	}
 }
 
-static void
+static struct lock *
-unlockscreen(Display *dpy, Lock *lock)
+lockscreen(Display *dpy, struct xrandr *rr, int screen)
-{
-	if(dpy == NULL || lock == NULL)
-		return;
-
-	XUngrabPointer(dpy, CurrentTime);
-	XUngrabKeyboard(dpy, CurrentTime);
-	XFreeColors(dpy, DefaultColormap(dpy, lock->screen), lock->colors, NUMCOLS, 0);
-	XFreePixmap(dpy, lock->pmap);
-	XDestroyWindow(dpy, lock->win);
-
-	free(lock);
-}
-
-static void
-cleanup(Display *dpy)
-{
-	int s;
-
-	for (s = 0; s < nscreens; ++s)
-		unlockscreen(dpy, locks[s]);
-
-	free(locks);
-	XCloseDisplay(dpy);
-}
-
-static Lock *
-lockscreen(Display *dpy, int screen)
 {
 	char curs[] = {0, 0, 0, 0, 0, 0, 0, 0};
 	int i, ptgrab, kbgrab;
-	Lock *lock;
+	struct lock *lock;
 	XColor color, dummy;
 	XSetWindowAttributes wa;
 	Cursor invisible;
 
-	if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(Lock))))
+	if (dpy == NULL || screen < 0 || !(lock = malloc(sizeof(struct lock))))
 		return NULL;
 
 	lock->screen = screen;
@@ -281,7 +255,7 @@ lockscreen(Display *dpy, int screen)
 		/* input is grabbed: we can lock the screen */
 		if (ptgrab == GrabSuccess && kbgrab == GrabSuccess) {
 			XMapRaised(dpy, lock->win);
-			if (rr)
+			if (rr->active)
 				XRRSelectInput(dpy, lock->win, RRScreenChangeNotifyMask);
 
 			XSelectInput(dpy, lock->root, SubstructureNotifyMask);
@@ -312,13 +286,15 @@ usage(void)
 
 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 *pws;
 	Display *dpy;
-	int s, nlocks;
+	int s, nlocks, nscreens;
 
 	ARGBEGIN {
 	case 'v':
@@ -360,16 +336,14 @@ main(int argc, char **argv) {
 		die("slock: setuid: %s\n", strerror(errno));
 
 	/* check for Xrandr support */
-	rr = XRRQueryExtension(dpy, &rrevbase, &rrerrbase);
+	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(Lock *)))) {
+	if (!(locks = calloc(nscreens, sizeof(struct lock *))))
-		XCloseDisplay(dpy);
 		die("slock: out of memory\n");
-	}
 	for (nlocks = 0, s = 0; s < nscreens; s++) {
-		if ((locks[s] = lockscreen(dpy, s)) != NULL)
+		if ((locks[s] = lockscreen(dpy, &rr, s)) != NULL)
 			nlocks++;
 		else
 			break;
@@ -377,16 +351,13 @@ main(int argc, char **argv) {
 	XSync(dpy, 0);
 
 	/* did we manage to lock everything? */
-	if (nlocks != nscreens) {
+	if (nlocks != nscreens)
-		cleanup(dpy);
 		return 1;
-	}
 
 	/* run post-lock command */
 	if (argc > 0) {
 		switch (fork()) {
 		case -1:
-			cleanup(dpy);
 			die("slock: fork failed: %s\n", strerror(errno));
 		case 0:
 			if (close(ConnectionNumber(dpy)) < 0)
@@ -399,10 +370,7 @@ main(int argc, char **argv) {
 	}
 
 	/* everything is now blank. Wait for the correct password */
-	readpw(dpy, pws);
+	readpw(dpy, &rr, locks, nscreens, pws);
-
-	/* password ok, unlock everything and quit */
-	cleanup(dpy);
 
 	return 0;
 }