some cleanups/fixes inspired by Jukka Salmi's feedback

event.c

@@ -267,7 +267,7 @@ expose(XEvent *e)
 static void
 keypress(XEvent *e)
 {
-	static unsigned int len = key ? sizeof(key) / sizeof(key[0]) : 0;
+	static unsigned int len = sizeof(key) / sizeof(key[0]);
 	unsigned int i;
 	KeySym keysym;
 	XKeyEvent *ev = &e->xkey;
@@ -370,7 +370,7 @@ void (*handler[LASTEvent]) (XEvent *) = {
 void
 grabkeys()
 {
-	static unsigned int len = key ? sizeof(key) / sizeof(key[0]) : 0;
+	static unsigned int len = sizeof(key) / sizeof(key[0]);
 	unsigned int i;
 	KeyCode code;
 

main.c

@@ -10,6 +10,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/select.h>
 #include <X11/cursorfont.h>
 #include <X11/Xatom.h>
 #include <X11/Xproto.h>
@@ -163,7 +164,7 @@ xerror(Display *dpy, XErrorEvent *ee)
 int
 main(int argc, char *argv[])
 {
-	int i, n;
+	int i;
 	unsigned int mask;
 	fd_set rd;
 	Bool readin = True;

tag.c

@@ -165,18 +165,13 @@ void
 settags(Client *c)
 {
 	char classinst[256];
-	static unsigned int len = rule ? sizeof(rule) / sizeof(rule[0]) : 0;
+	static unsigned int len = sizeof(rule) / sizeof(rule[0]);
 	unsigned int i, j;
 	regex_t regex;
 	regmatch_t tmp;
 	Bool matched = False;
 	XClassHint ch;
 
-	if(!len) {
-		c->tags[tsel] = tags[tsel];
-		return;
-	}
-
 	if(XGetClassHint(dpy, c->win, &ch)) {
 		snprintf(classinst, sizeof(classinst), "%s:%s",
 				ch.res_class ? ch.res_class : "",

util.c

@@ -15,9 +15,7 @@
 static void
 bad_malloc(unsigned int size)
 {
-	fprintf(stderr, "fatal: could not malloc() %d bytes\n",
-			(int) size);
-	exit(EXIT_FAILURE);
+	eprint("fatal: could not malloc() %u bytes\n", size);
 }
 
 /* extern */
@@ -58,7 +56,7 @@ spawn(Arg *arg)
 			fprintf(stderr, "dwm: execvp %s", argv[0]);
 			perror(" failed");
 		}
-		exit(EXIT_FAILURE);
+		exit(0);
 	}
 	wait(0);
 }