fix(utils): protect against errors in str_replace

Protect against misuse of str_replace if the replace string is larger
than the find string by forcing an exit with error.

utils.c

@@ -5,6 +5,11 @@
 
 #include "utils.h"
 
+#ifndef _WIN32
+ #include <err.h>
+ #include <sysexits.h>
+#endif
+
 #if !HAVE_STRNSTR
 
 /*
@@ -138,9 +143,15 @@ str_replace(char *source, char *find, char *replace)
 	int rlen = strlen(replace);
 	int flen = strlen(find);
 
+	if (rlen > flen) {
+		err(EX_SOFTWARE, "str_replace: replace is larger than find");
+	}
+
 	while (NULL != s) {
-		strncpy(s, replace, rlen);
-		strcpy(s + rlen, s + flen);
+		strncpy(s, replace, rlen); // -Wstringop-truncation warning here is a false positive.
+		if (rlen < flen) {
+			strcpy(s + rlen, s + flen);
+		}
 		s += rlen;
 		s = strstr(s, find);
 	}

utils.h

@@ -8,6 +8,8 @@
 #define QSTAT_UTILS_H
 
 #ifndef _WIN32
+ #include <err.h>
+ #include <sysexits.h>
  #ifdef HAVE_CONFIG_H
 	#include "gnuconfig.h"
  #endif
@@ -43,6 +45,10 @@
 	#define EX_OSERR    71  /* system error (e.g., can't fork) */
 #endif
 
+#ifndef EX_SOFTWARE
+	#define EX_SOFTWARE 70 /* An internal software error has been detected */
+#endif
+
 #if !HAVE_ERR_H
 	void err(int eval, const char *fmt, ...);
 	void warn(const char *fmt, ...);