Fix pipe transmission from forked dnsmasq process validation changed configurations

Signed-off-by: DL6ER <dl6er@dl6er.de>

src/config/dnsmasq_config.c

@@ -89,19 +89,21 @@ static bool test_dnsmasq_config(char errbuf[ERRBUF_SIZE])
 		// Read readirected STDERR until EOF
 		if(errbuf != NULL)
 		{
-			// We are only interested in the last pipe line
 			while(read(pipefd[0], errbuf, ERRBUF_SIZE) > 0)
 			{
-				// Remove initial newline character (if present)
-				if(errbuf[0] == '\n')
-					memmove(errbuf, &errbuf[1], ERRBUF_SIZE-1);
+				char *ptr = errbuf;
+				// Remove initial newline characters and '~'s (if present)
+				while(*ptr == '\n' || *ptr == '~') ptr++;
+				memmove(errbuf, ptr, ERRBUF_SIZE - (ptr - errbuf));
+
 				// Strip newline character (if present)
 				if(errbuf[strlen(errbuf)-1] == '\n')
 					errbuf[strlen(errbuf)-1] = '\0';
+
 				// Replace any possible internal newline characters by spaces
-				char *ptr = errbuf;
 				while((ptr = strchr(ptr, '\n')) != NULL)
 					*ptr = ' ';
+
 				log_debug(DEBUG_CONFIG, "dnsmasq pipe: %s", errbuf);
 			}
 		}

src/dnsmasq/log.c

@@ -332,6 +332,16 @@ void my_syslog(int priority, const char *format, ...)
 
   if (echo_stderr) 
     {
+      /********** Pi-hole modification *************/
+      if(only_testing)
+        // Print 32 bytes filled with '~' to the pipe to signal the
+        // beginning of the output. This is necessary as sometimes the
+        // very first bytes of the output are lost in the pipe and we
+        // need to know where the output starts
+        for(int i = 0; i < 32; i++)
+          fputc('~', stderr);
+      /*********************************************/
+
       fprintf(stderr, "dnsmasq%s: ", func);
       va_start(ap, format);
       vfprintf(stderr, format, ap);

test/test_suite.bats

@@ -1524,7 +1524,7 @@
 
   run bash -c './pihole-FTL --config dns.revServers "[\"true,1.1.1.1,def,ghi\"]"'
   printf "%s\n" "${lines[@]}"
-  [[ ${lines[0]} == 'New dnsmasq configuration is not valid ('*'Name does not resolve at line '*' of /etc/pihole/dnsmasq.conf.temp: "rev-server=1.1.1.1,def"), config remains unchanged' ]]
+  [[ ${lines[0]} == 'New dnsmasq configuration is not valid (dnsmasq: Name does not resolve at line '*' of /etc/pihole/dnsmasq.conf.temp: "rev-server=1.1.1.1,def"), config remains unchanged' ]]
   [[ $status == 3 ]]
 
   run bash -c './pihole-FTL --config webserver.api.excludeClients "[\".*\",\"$$$\",\"[[[\"]"'