Improve Swift API delegate log outputter

Capture whence information in all Serval logging API entry points.

Introduce the LogLevel enum type to avoid exposing internal C API
details in the Swift API.

Rename Swift API methods and types to use camelCase naming style, to
distinguish it from the C API, which uses under_score naming style.

log.c

@@ -179,12 +179,19 @@ static void log_close(struct log_output_iterator *it)
     (*it->output)->close(it);
 }
 
-static void log_capture_fd(struct log_output_iterator *it, int fd, bool_t *captured)
+static bool_t log_capture_fd(struct log_output_iterator *it, int fd)
 {
   assert(it->output);
   assert(*it->output);
-  if ((*it->output)->capture_fd)
-    (*it->output)->capture_fd(it, fd, captured);
+  return (*it->output)->capture_fd ? (*it->output)->capture_fd(it, fd) : 0;
+}
+
+static void log_suppress_fd(struct log_output_iterator *it, int fd)
+{
+  assert(it->output);
+  assert(*it->output);
+  if ((*it->output)->suppress_fd)
+    (*it->output)->suppress_fd(it, fd);
 }
 
 /* Functions for use by log outputters.  This is the "private" API of the logging system, as
@@ -333,7 +340,12 @@ bool_t serval_log_capture_fd(int fd) {
   struct log_output_iterator it;
   log_iterator_start(&it);
   bool_t captured = 0;
+  while (!captured && log_iterator_advance(&it))
+    captured = log_capture_fd(&it, fd);
+  if (captured) {
+    log_iterator_start(&it);
     while (log_iterator_advance(&it))
-    log_capture_fd(&it, fd, &captured);
+      log_suppress_fd(&it, fd);
+  }
   return captured;
 }

log_output.h

@@ -66,10 +66,15 @@ struct log_output {
   //   vlogMessage() primitive, before start_line() is called.
   void (*open)(struct log_output_iterator *it);
 
-  //   If *capture is 0 and the output is of a persistent nature (eg, a file or
-  //   system log) and is able to redirect data written to the given file
-  //   descriptor to its output, then do so and set *capture to 1.
-  void (*capture_fd)(struct log_output_iterator *it, int fd, bool_t *capture);
+  //   If the output is of a persistent nature (eg, a file or system log) and
+  //   is able to redirect data written to the given file descriptor to its
+  //   output, then do so and return true, otherwise return false.
+  bool_t (*capture_fd)(struct log_output_iterator *it, int fd);
+
+  //   Cease writing any output to the given file descriptor.  This is called
+  //   on all outputters immediately after any outputter's capture_fd(fd) call
+  //   returns true, to prevent duplicate log messages being captured.
+  void (*suppress_fd)(struct log_output_iterator *it, int fd);
 
   //   Test whether output is able to handle messages; if it returns false then
   //   start_line() and end_line() will not be invoked.

log_output_console.c

@@ -82,8 +82,10 @@ static void open_log_console(struct log_output_iterator *it)
   }
 }
 
-static void capture_fd_log_console(struct log_output_iterator *it, int fd, bool_t *UNUSED(capture))
+static void suppress_fd_log_console(struct log_output_iterator *it, int fd)
 {
+  // If another log outputter is capturing the console's output (eg, the logfile outputer), then
+  // cease logging to the console to avoid duplicate messages being sent to that output.
   struct log_output_console_state *state = _state(*it->output);
   if (state->fp && state->fp != DISABLED && fileno(state->fp) == fd) {
     fflush(state->fp);
@@ -137,7 +139,8 @@ static struct log_output static_log_output = {
   .show_time = log_console_show_time,
   .state = &static_state,
   .open = open_log_console,
-  .capture_fd = capture_fd_log_console,
+  .capture_fd = NULL,
+  .suppress_fd = suppress_fd_log_console,
   .is_available = is_log_console_available,
   .start_line = log_console_start_line,
   .end_line = log_console_end_line,

log_output_delegate.c

@@ -84,6 +84,17 @@ static void log_delegate_open(struct log_output_iterator *it)
   }
 }
 
+static bool_t log_delegate_capture_fd(struct log_output_iterator *UNUSED(it), int fd)
+{
+  return serval_log_delegate.capture_fd && serval_log_delegate.capture_fd(fd);
+}
+
+static void log_delegate_suppress_fd(struct log_output_iterator *UNUSED(it), int fd)
+{
+  if (serval_log_delegate.suppress_fd)
+    serval_log_delegate.suppress_fd(fd);
+}
+
 static void log_delegate_start_line(struct log_output_iterator *it, int UNUSED(level))
 {
   struct log_output_delegate_state *state = _state(*it->output);
@@ -113,7 +124,8 @@ static struct log_output static_log_output = {
   .show_time = log_delegate_show_time,
   .state = &static_state,
   .open = log_delegate_open,
-  .capture_fd = NULL,
+  .capture_fd = log_delegate_capture_fd,
+  .suppress_fd = log_delegate_suppress_fd,
   .is_available = is_log_delegate_available,
   .start_line = log_delegate_start_line,
   .end_line = log_delegate_end_line,
@@ -130,5 +142,7 @@ struct log_delegate serval_log_delegate = {
     .show_pid = 0,
     .show_time = 1,
     .print = NULL,
-    .flush = NULL
+    .flush = NULL,
+    .capture_fd = NULL,
+    .suppress_fd = NULL
 };

log_output_delegate.h

@@ -29,6 +29,8 @@ struct log_delegate {
     bool_t show_time;
     void (*print)(int level, const char *message, bool_t overrun);
     void (*flush)();
+    bool_t (*capture_fd)(int fd);
+    void (*suppress_fd)(int fd);
 };
 
 extern struct log_delegate serval_log_delegate;

log_output_file.c

@@ -310,9 +310,9 @@ static void open_log_file(struct log_output_iterator *it)
   }
 }
 
-static void capture_fd_log_file(struct log_output_iterator *it, int fd, bool_t *capture)
+static bool_t capture_fd_log_file(struct log_output_iterator *it, int fd)
 {
-  if (!*capture) {
+  bool_t captured = 0;
   // This outputter does not connect the file descriptor to an output file until the next log
   // message is output.
   _state(*it->output)->capture_fd = fd;
@@ -321,15 +321,16 @@ static void capture_fd_log_file(struct log_output_iterator *it, int fd, bool_t *
   int devnull;
   if ((devnull = open("/dev/null", O_RDWR, 0)) == -1)
     WHY_perror("open(\"/dev/null\")");
+  else if (devnull == fd)
+    captured = 1;
   else {
-      if (devnull != fd && dup2(devnull, fd) == -1)
+    if (dup2(devnull, fd) == -1)
       WHYF_perror("dup2(%d, %d)", devnull, fd);
     else
-	*capture = 1;
-      if (devnull != fd)
+      captured = 1;
     close(devnull);
   }
-  }
+  return captured;
 }
 
 static bool_t is_log_file_available(const struct log_output_iterator *it)
@@ -377,6 +378,7 @@ static struct log_output static_log_output = {
   .state = &static_state,
   .open = open_log_file,
   .capture_fd = capture_fd_log_file,
+  .suppress_fd = NULL,
   .is_available = is_log_file_available,
   .start_line = log_file_start_line,
   .end_line = NULL,

servaldswift.swift

@@ -22,7 +22,7 @@ import ServalDNA
 
 // Logging
 
-logSetup()
+servalLogSetup(minimum_level: .debug)
 
 // Output
 

swift-daemon-api/Sources/log.swift

@@ -19,40 +19,81 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 import serval_dna.lib
 
-private func serval_log(level: CInt, format: String, va_list: CVaListPointer) {
-    format.withCString { CString in
-        serval_vlogf(level, __whence, CString, va_list)
-    }
-}
+public enum LogLevel {
+    case debug
+    case info
+    case hint
+    case warn
+    case error
+    case fatal
 
-public func serval_log(level: CInt, text: String) {
-    text.withCString { CString in
-        withVaList([CString]) { va_list in
-            serval_log(level: level, format: "%s", va_list: va_list)
+    var rawValue : CInt {
+        get {
+            switch (self) {
+            case .debug: return LOG_LEVEL_DEBUG
+            case .info: return LOG_LEVEL_INFO
+            case .hint: return LOG_LEVEL_HINT
+            case .warn: return LOG_LEVEL_WARN
+            case .error: return LOG_LEVEL_ERROR
+            case .fatal: return LOG_LEVEL_FATAL
+            }
         }
     }
 }
 
-public func serval_log_fatal(_ text: String) {
-    serval_log(level: LOG_LEVEL_FATAL, text: text)
+internal var baseFilePath : String = #file
+
+private func trimpath(_ path: String) -> String {
+    var i = path.startIndex
+    for (b, p) in zip(baseFilePath.indices, path.indices) {
+        if path[p] != baseFilePath[b] {
+            break;
+        }
+        if path[p] == "/" {
+            i = path.index(after: p)
+        }
+    }
+    return String(path[i..<path.endIndex])
 }
 
-public func serval_log_error(_ text: String) {
-    serval_log(level: LOG_LEVEL_ERROR, text: text)
+private func servalLog(level: LogLevel, format: String, va_list: CVaListPointer, file: String = #file, line: Int = #line, function: String = #function) {
+    trimpath(file).withCString { c_file in
+        function.withCString { c_function in
+            format.withCString { c_format in
+                serval_vlogf(level.rawValue, __sourceloc(file: c_file, line: UInt32(exactly: line) ?? 0, function: c_function), c_format, va_list)
+            }
+        }
+    }
 }
 
-public func serval_log_warning(_ text: String) {
-    serval_log(level: LOG_LEVEL_WARN, text: text)
+public func servalLog(level: LogLevel, text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    text.withCString { c_text in
+        withVaList([c_text]) { va_list in
+            servalLog(level: level, format: "%s", va_list: va_list, file: file, line: line, function: function)
+        }
+    }
 }
 
-public func serval_log_hint(_ text: String) {
-    serval_log(level: LOG_LEVEL_HINT, text: text)
+public func servalLogFatal(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .fatal, text: text, file: file, line: line, function: function)
 }
 
-public func serval_log_info(_ text: String) {
-    serval_log(level: LOG_LEVEL_INFO, text: text)
+public func servalLogError(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .error, text: text, file: file, line: line, function: function)
 }
 
-public func serval_log_debug(_ text: String) {
-    serval_log(level: LOG_LEVEL_DEBUG, text: text)
+public func servalLogWarning(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .warn, text: text, file: file, line: line, function: function)
+}
+
+public func servalLogHint(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .hint, text: text, file: file, line: line, function: function)
+}
+
+public func servalLogInfo(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .info, text: text, file: file, line: line, function: function)
+}
+
+public func servalLogDebug(_ text: String, file: String = #file, line: Int = #line, function: String = #function) {
+    servalLog(level: .debug, text: text, file: file, line: line, function: function)
 }

swift-daemon-api/Sources/log_output.swift

@@ -67,9 +67,17 @@ private func logPrint(_ level: CInt, _ message: UnsafePointer<CChar>?, _ overrun
 
 #endif
 
-public func logSetup() {
+private func logSuppress(_ fd: CInt) {
+    if (fd == FileHandle.standardError.fileDescriptor) {
+        serval_log_delegate.print = nil
+    }
+}
+
+public func servalLogSetup(minimum_level: LogLevel = .info, baseFilePath file: String = #file) {
+    baseFilePath = file
     serval_log_delegate.print = logPrint
-    serval_log_delegate.minimum_level = LOG_LEVEL_DEBUG
+    serval_log_delegate.suppress_fd = logSuppress
+    serval_log_delegate.minimum_level = minimum_level.rawValue
     serval_log_delegate.show_prolog = 1
 #if os(iOS) || os(macOS)
     // Apple's unified logging system (iOS) and syslog (macOS) both record the

whence.c

@@ -64,7 +64,9 @@ void xprint_sourceloc(XPRINTF xpf, struct __sourceloc loc)
   if (loc.function && loc.function[0]) {
     if (flag)
       xputc(':', xpf);
-    xprintf(xpf, "%s()", loc.function);
+    xprintf(xpf, "%s", loc.function);
+    if (loc.function[strlen(loc.function) - 1] != ')')
+      xputs("()", xpf);
     ++flag;
   }
 }