helpful errors

dmenu.c

@@ -440,9 +440,9 @@ readstdin(void) {
 		if((p = strchr(buf, '\n')))
 			*p = '\0';
 		if(!(item = calloc(1, sizeof *item)))
-			eprintf("cannot malloc %u bytes\n", sizeof *item);
+			eprintf("cannot malloc %u bytes:", sizeof *item);
 		if(!(item->text = strdup(buf)))
-			eprintf("cannot strdup %u bytes\n", strlen(buf)+1);
+			eprintf("cannot strdup %u bytes:", strlen(buf)+1);
 		inputw = MAX(inputw, textw(dc, item->text));
 	}
 }

draw.c

@@ -68,6 +68,11 @@ eprintf(const char *fmt, ...) {
 	va_start(ap, fmt);
 	vfprintf(stderr, fmt, ap);
 	va_end(ap);
+
+	if(fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	}
 	exit(EXIT_FAILURE);
 }
 
@@ -101,7 +106,7 @@ initdc(void) {
 	if(!setlocale(LC_CTYPE, "") || !XSupportsLocale())
 		weprintf("no locale support\n");
 	if(!(dc = calloc(1, sizeof *dc)))
-		eprintf("cannot malloc %u bytes\n", sizeof *dc);
+		eprintf("cannot malloc %u bytes:", sizeof *dc);
 	if(!(dc->dpy = XOpenDisplay(NULL)))
 		eprintf("cannot open display\n");