From 4de8b733fdd6f8ba6ddb9aa1d2c0f0810e7568a6 Mon Sep 17 00:00:00 2001
From: Nick Briggs <nicholas.h.briggs@gmail.com>
Date: Mon, 19 May 2025 11:45:54 -0700
Subject: [PATCH] Replaces unchecked strcpy/strcat with strlcpy/strlcat

Unchecked writes to strings using strcpy and strcat can cause memory smashes,
replacing them with (destination) bounds checked strl... equivalents can
avoid this.

Incidentally, fix construction of file name for $HOME/.Xdefaults
---
 src/xrdopt.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/src/xrdopt.c b/src/xrdopt.c
index f309857..43e3de3 100644
--- a/src/xrdopt.c
+++ b/src/xrdopt.c
@@ -17,7 +17,7 @@
 #include <limits.h>         // for PATH_MAX
 #include <stdio.h>          // for fprintf, NULL, stderr, sscanf
 #include <stdlib.h>         // for getenv, exit, strtol
-#include <string.h>         // for strncpy, strcat, strcpy, strcmp
+#include <string.h>         // for strncpy, strlcat, strlcpy, strcmp
 #include <sys/types.h>      // for u_char
 #include <unistd.h>         // for access, R_OK
 #include "xdefs.h"          // for WINDOW_NAME
@@ -211,13 +211,13 @@ void read_Xoption(int *argc, char *argv[])
     print_Xusage(argv[0]);
   } else {
     envname = getenv("DISPLAY");
-    (void)strcpy(Display_Name, envname);
+    (void)strlcpy(Display_Name, envname, sizeof(Display_Name));
   }
   if ((xdisplay = XOpenDisplay(Display_Name)) != NULL) {
     /* read the other databases */
     /* Start with app-defaults/medley */
-    (void)strcpy(tmp, "/usr/lib/X11/app-defaults/");
-    (void)strcat(tmp, "medley");
+    (void)strlcpy(tmp, "/usr/lib/X11/app-defaults/", sizeof(tmp));
+    (void)strlcat(tmp, "medley", sizeof(tmp));
     applicationDB = XrmGetFileDatabase(tmp);
     if (applicationDB != NULL) { (void)XrmMergeDatabases(applicationDB, &rDB); }
     /* Then try the displays defaults */
@@ -232,8 +232,8 @@ void read_Xoption(int *argc, char *argv[])
   }
 
   envname = getenv("HOME");
-  (void)strcat(tmp, envname);
-  (void)strcat(tmp, "/.Xdefaults");
+  (void)strlcpy(tmp, envname, sizeof(tmp));
+  (void)strlcat(tmp, "/.Xdefaults", sizeof(tmp));
   if (access(tmp, R_OK) != 0) {
     serverDB = XrmGetFileDatabase(tmp);
     if (serverDB != NULL) { (void)XrmMergeDatabases(serverDB, &rDB); }
@@ -255,7 +255,7 @@ void read_Xoption(int *argc, char *argv[])
   if (XrmGetResource(rDB, "ldex.icontitle", "Ldex.icontitle", str_type, &value) == True) {
     (void)strncpy(iconTitle, value.addr, value.size);
   } else {
-    (void)strcpy(iconTitle, "Medley");
+    (void)strlcpy(iconTitle, "Medley", sizeof(iconTitle));
   }
 
   if (XrmGetResource(rDB, "ldex.iconbitmap", "Ldex.Iconbitmap", str_type, &value) == True) {
@@ -276,8 +276,6 @@ void read_Xoption(int *argc, char *argv[])
                              &LispDisplayRequestedWidth, &LispDisplayRequestedHeight);
   }
 
-  (void)strcpy(tmp, ""); /* Clear the string */
-
   if (XrmGetResource(rDB, "ldex.cursorColor", "Ldex.cursorColor", str_type, &value) == True) {
     (void)strncpy(cursorColor, value.addr, sizeof(cursorColor) - 1);
   }