[PATCH 1/3] Localize and rework data structures

From: FRIGN <dev_AT_frign.de>
Date: Sun, 11 Sep 2016 23:08:19 +0200

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 | 62 ++++++++++++++++++++++++++++++++++----------------------------
 1 file changed, 34 insertions(+), 28 deletions(-)
diff --git a/slock.c b/slock.c
index 7127ebe..83f6810 100644
--- a/slock.c
+++ b/slock.c
_AT_@ -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;
-static int nscreens;
-static Bool rr;
-static int rrevbase;
-static int rrerrbase;
+struct xrandr {
+	int active;
+	int evbase;
+	int errbase;
+};
 
 static void
 die(const char *errstr, ...)
_AT_@ -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;
_AT_@ -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) {
_AT_@ -208,7 +209,7 @@ readpw(Display *dpy, const char *pws)
 }
 
 static void
-unlockscreen(Display *dpy, Lock *lock)
+unlockscreen(Display *dpy, struct lock *lock)
 {
 	if(dpy == NULL || lock == NULL)
 		return;
_AT_@ -223,28 +224,31 @@ unlockscreen(Display *dpy, Lock *lock)
 }
 
 static void
-cleanup(Display *dpy)
+cleanup(Display **dpy, struct lock ***locks, int *nscreens)
 {
 	int s;
 
-	for (s = 0; s < nscreens; ++s)
-		unlockscreen(dpy, locks[s]);
+	for (s = 0; s < *nscreens; ++s)
+		unlockscreen(*dpy, (*locks)[s]);
+	*nscreens = 0;
 
-	free(locks);
-	XCloseDisplay(dpy);
+	free(*locks);
+	*locks = NULL;
+	XCloseDisplay(*dpy);
+	*dpy = NULL;
 }
 
-static Lock *
-lockscreen(Display *dpy, int screen)
+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;
-	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;
_AT_@ -281,7 +285,7 @@ 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);
_AT_@ -312,13 +316,15 @@ 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':
_AT_@ -360,16 +366,16 @@ 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;
_AT_@ -378,7 +384,7 @@ main(int argc, char **argv) {
 
 	/* did we manage to lock everything? */
 	if (nlocks != nscreens) {
-		cleanup(dpy);
+		cleanup(&dpy, &locks, &nscreens);
 		return 1;
 	}
 
_AT_@ -386,7 +392,7 @@ main(int argc, char **argv) {
 	if (argc > 0) {
 		switch (fork()) {
 		case -1:
-			cleanup(dpy);
+			cleanup(&dpy, &locks, &nscreens);
 			die("slock: fork failed: %s\n", strerror(errno));
 		case 0:
 			if (close(ConnectionNumber(dpy)) < 0)
_AT_@ -399,10 +405,10 @@ 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);
+	cleanup(&dpy, &locks, &nscreens);
 
 	return 0;
 }
-- 
2.7.3
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Received on Mon Sep 17 2001 - 00:00:00 CEST