Logging: Tag the entries in the merged log

So we know which entry is from the app and which is from the network
extension.

WireGuard/Shared/Logging/Logger.swift

@@ -14,16 +14,20 @@ class Logger {
         return (logPtr != nil)
     }
 
-    static func writeLog(mergedWith otherLogFile: String, to targetFile: String) -> Bool {
+    static func writeLog(mergedWith otherLogFile: String, tag: String, otherTag: String, to targetFile: String) -> Bool {
         let otherlogPtr = otherLogFile.withCString { otherLogFileCStr -> UnsafeMutablePointer<log>? in
             return open_log(otherLogFileCStr)
         }
         if let thisLogPtr = Logger.logPtr, let otherlogPtr = otherlogPtr {
             return targetFile.withCString { targetFileCStr -> Bool in
-                let returnValue = write_logs_to_file(targetFileCStr, thisLogPtr, otherlogPtr)
+                return tag.withCString { tagCStr -> Bool in
+                    return otherTag.withCString { otherTagCStr -> Bool in
+                        let returnValue = write_logs_to_file(targetFileCStr, tagCStr, thisLogPtr, otherTagCStr, otherlogPtr)
                         return (returnValue == 0)
                     }
                 }
+            }
+        }
         return false
     }
 }

WireGuard/Shared/Logging/ringlogger.c

@@ -49,7 +49,7 @@ static bool first_before_second(const struct log_line *line1, const struct log_l
 	return false;
 }
 
-int write_logs_to_file(const char *file_name, const struct log *log1, const struct log *log2)
+int write_logs_to_file(const char *file_name, const char *tag1, const struct log *log1, const char *tag2, const struct log *log2)
 {
 	uint32_t i1, i2, len1 = log1->header.len, len2 = log2->header.len;
 	char buf[MAX_LOG_LINE_LENGTH];
@@ -68,19 +68,22 @@ int write_logs_to_file(const char *file_name, const struct log *log1, const stru
 		const struct log_line *line1 = &log1->lines[(log1->header.first + i1) % MAX_LINES];
 		const struct log_line *line2 = &log2->lines[(log2->header.first + i2) % MAX_LINES];
 		const struct log_line *line;
+		const char *tag;
 
 		if (i1 < len1 && (i2 >= len2 || first_before_second(line1, line2))) {
 			line = line1;
+			tag = (const char *) tag1;
 			++i1;
 		} else if (i2 < len2 && (i1 >= len1 || first_before_second(line2, line1))) {
 			line = line2;
+			tag = (const char *) tag2;
 			++i2;
 		} else {
 			break;
 		}
 		memcpy(buf, line->line, MAX_LOG_LINE_LENGTH);
 		buf[MAX_LOG_LINE_LENGTH - 1] = '\0';
-		if (fprintf(file, "%lu.%06d: %s\n", line->tv.tv_sec, line->tv.tv_usec, buf) < 0) {
+		if (fprintf(file, "%lu.%06d: [%s] %s\n", line->tv.tv_sec, line->tv.tv_usec, tag, buf) < 0) {
 			int ret = -errno;
 			fclose(file);
 			return ret;

WireGuard/Shared/Logging/ringlogger.h

@@ -24,7 +24,7 @@ struct log {
 };
 
 void write_msg_to_log(struct log *log, const char *msg);
-int write_logs_to_file(const char *file_name, const struct log *log1, const struct log *log2);
+int write_logs_to_file(const char *file_name, const char *tag1, const struct log *log1, const char *tag2, const struct log *log2);
 struct log *open_log(const char *file_name);
 
 #endif

WireGuard/WireGuard/UI/iOS/SettingsTableViewController.swift

@@ -118,7 +118,7 @@ class SettingsTableViewController: UITableViewController {
                 return
             }
 
-            let isWritten = Logger.writeLog(mergedWith: networkExtensionLogFilePath, to: destinationURL.path)
+            let isWritten = Logger.writeLog(mergedWith: networkExtensionLogFilePath, tag: "APP", otherTag: "EXT", to: destinationURL.path)
             guard isWritten else {
                 ErrorPresenter.showErrorAlert(title: "Log export failed", message: "Internal error merging logs", from: self)
                 return