From a4fe8c97414f07dd8b891e0d325dd2733195151d Mon Sep 17 00:00:00 2001
From: Laslo Hunhold <dev@frign.de>
Date: Fri, 18 May 2018 10:07:50 +0200
Subject: [PATCH] Audit slstatus.c

 1) Remove setlocale() (locales are harmful and any 'issues' shall
    be fixed in different ways that are expected).
 2) Disable buffering on stdout with setbuf() rather than flushing
    it each time.
 3) Make error messages more consistent.
 4) Add error checks where applicable.
 5) Make code a bit more readable where res is assigned.
 6) Use XFlush() rather than XSync() (we don't need to wait for the
    XServer to react, which could lead to long hangs on our side).
---
 slstatus.c | 48 +++++++++++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/slstatus.c b/slstatus.c
index 35bdcd6..7ff323f 100644
--- a/slstatus.c
+++ b/slstatus.c
@@ -1,6 +1,5 @@
 /* See LICENSE file for copyright and license details. */
 #include <errno.h>
-#include <locale.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -56,6 +55,7 @@ main(int argc, char *argv[])
 	size_t i, len;
 	int sflag, ret;
 	char status[MAXLEN];
+	const char *res;
 
 	sflag = 0;
 	ARGBEGIN {
@@ -70,25 +70,31 @@ main(int argc, char *argv[])
 		usage();
 	}
 
-	setlocale(LC_ALL, "");
-
 	memset(&act, 0, sizeof(act));
 	act.sa_handler = terminate;
 	sigaction(SIGINT,  &act, NULL);
 	sigaction(SIGTERM, &act, NULL);
 
+	if (sflag) {
+		setbuf(stdout, NULL);
+	}
+
 	if (!sflag && !(dpy = XOpenDisplay(NULL))) {
-		fprintf(stderr, "Cannot open display");
+		fprintf(stderr, "XOpenDisplay: Failed to open display\n");
 		return 1;
 	}
 
 	while (!done) {
-		clock_gettime(CLOCK_MONOTONIC, &start);
+		if (clock_gettime(CLOCK_MONOTONIC, &start) < 0) {
+			fprintf(stderr, "clock_gettime: %s\n", strerror(errno));
+			return 1;
+		}
 
 		status[0] = '\0';
 		for (i = len = 0; i < LEN(args); i++) {
-			const char * res = args[i].func(args[i].args);
-			res = (res == NULL) ? unknown_str : res;
+			if (!(res = args[i].func(args[i].args))) {
+				res = unknown_str;
+			}
 			if ((ret = snprintf(status + len, sizeof(status) - len,
 			                    args[i].fmt, res)) < 0) {
 				fprintf(stderr, "snprintf: %s\n",
@@ -103,14 +109,21 @@ main(int argc, char *argv[])
 
 		if (sflag) {
 			printf("%s\n", status);
-			fflush(stdout);
 		} else {
-			XStoreName(dpy, DefaultRootWindow(dpy), status);
-			XSync(dpy, False);
+			if (XStoreName(dpy, DefaultRootWindow(dpy), status) < 0) {
+				fprintf(stderr,
+				        "XStoreName: Allocation failed\n");
+				return 1;
+			}
+			XFlush(dpy);
 		}
 
 		if (!done) {
-			clock_gettime(CLOCK_MONOTONIC, &current);
+			if (clock_gettime(CLOCK_MONOTONIC, &current) < 0) {
+				fprintf(stderr, "clock_gettime: %s\n",
+				        strerror(errno));
+				return 1;
+			}
 			difftimespec(&diff, &current, &start);
 
 			intspec.tv_sec = interval / 1000;
@@ -118,14 +131,23 @@ main(int argc, char *argv[])
 			difftimespec(&wait, &intspec, &diff);
 
 			if (wait.tv_sec >= 0) {
-				nanosleep(&wait, NULL);
+				if (nanosleep(&wait, NULL) < 0 &&
+				    errno != EINTR) {
+					fprintf(stderr, "nanosleep: %s\n",
+					        strerror(errno));
+					return 1;
+				}
 			}
 		}
 	}
 
 	if (!sflag) {
 		XStoreName(dpy, DefaultRootWindow(dpy), NULL);
-		XCloseDisplay(dpy);
+		if (XCloseDisplay(dpy) < 0) {
+			fprintf(stderr,
+			        "XCloseDisplay: Failed to close display\n");
+			return 1;
+		}
 	}
 
 	return 0;