[vlc-devel] [PATCH 1/2] libvlc: replaced libvlc_log_set with a formatted log callback

[Jérémy VIGNELLES]

---
 include/vlc/libvlc.h  | 25 ++++++++++++-------------
 lib/libvlc.sym        |  2 +-
 lib/libvlc_internal.h |  3 ++-
 lib/log.c             | 29 +++++++++++++++++++----------
 4 files changed, 34 insertions(+), 25 deletions(-)

diff --git a/include/vlc/libvlc.h b/include/vlc/libvlc.h
index 0ec0045..aac2c7f 100644
--- a/include/vlc/libvlc.h
+++ b/include/vlc/libvlc.h
@@ -410,19 +410,18 @@ LIBVLC_API void libvlc_log_get_object(const libvlc_log_t *ctx,
                         const char **name, const char **header, uintptr_t *id);
 
 /**
- * Callback prototype for LibVLC log message handler.
+ * Callback prototype for LibVLC preformatted log message handler.
  *
  * \param data data pointer as given to libvlc_log_set()
  * \param level message level (@ref libvlc_log_level)
  * \param ctx message context (meta-information about the message)
- * \param fmt printf() format string (as defined by ISO C11)
- * \param args variable argument list for the format
+ * \param message the message, already formatted
  * \note Log message handlers <b>must</b> be thread-safe.
- * \warning The message context pointer, the format string parameters and the
- *          variable arguments are only valid until the callback returns.
+ * \warning The message context pointer, and the message string parameters
+ *          are only valid until the callback returns.
  */
-typedef void (*libvlc_log_cb)(void *data, int level, const libvlc_log_t *ctx,
-                              const char *fmt, va_list args);
+typedef void (*libvlc_log_preformatted_cb)(void *data, int level, const libvlc_log_t *ctx,
+                              const char *message);
 
 /**
  * Unsets the logging callback.
@@ -440,11 +439,13 @@ typedef void (*libvlc_log_cb)(void *data, int level, const libvlc_log_t *ctx,
 LIBVLC_API void libvlc_log_unset( libvlc_instance_t *p_instance );
 
 /**
- * Sets the logging callback for a LibVLC instance.
+ * Sets the logging callback for a LibVLC instance, that takes a preformatted message as input.
  *
  * This function is thread-safe: it will wait for any pending callbacks
  * invocation to complete.
  *
+ * \param p_instance libvlc instance
+ * \param min_level the callback will only be called if the message level is above this level, 0 means "get all messages" (@ref libvlc_log_level)
  * \param cb callback function pointer
  * \param data opaque data pointer for the callback function
  *
@@ -453,12 +454,10 @@ LIBVLC_API void libvlc_log_unset( libvlc_instance_t *p_instance );
  *
  * \warning A deadlock may occur if this function is called from the callback.
  *
- * \param p_instance libvlc instance
- * \version LibVLC 2.1.0 or later
+ * \version LibVLC 4.0.0 or later
  */
-LIBVLC_API void libvlc_log_set( libvlc_instance_t *p_instance,
-                                libvlc_log_cb cb, void *data );
-
+LIBVLC_API void libvlc_log_set_preformatted(libvlc_instance_t *p_instance, int min_level,
+                                            libvlc_log_preformatted_cb cb, void* data );
 
 /**
  * Sets up logging to a file.
diff --git a/lib/libvlc.sym b/lib/libvlc.sym
index 456f9c2..59208c8 100644
--- a/lib/libvlc.sym
+++ b/lib/libvlc.sym
@@ -55,8 +55,8 @@ libvlc_get_fullscreen
 libvlc_get_version
 libvlc_log_get_context
 libvlc_log_get_object
-libvlc_log_set
 libvlc_log_set_file
+libvlc_log_set_preformatted
 libvlc_log_unset
 libvlc_media_add_option
 libvlc_media_add_option_flag
diff --git a/lib/libvlc_internal.h b/lib/libvlc_internal.h
index 5c1107b..8c39aa2 100644
--- a/lib/libvlc_internal.h
+++ b/lib/libvlc_internal.h
@@ -65,7 +65,8 @@ struct libvlc_instance_t
     struct libvlc_callback_entry_list_t *p_callback_list;
     struct
     {
-        void (*cb) (void *, int, const libvlc_log_t *, const char *, va_list);
+        void (*cb) (void *, int, const libvlc_log_t *, const char *);
+        int min_level;
         void *data;
     } log;
     struct
diff --git a/lib/log.c b/lib/log.c
index 66e0d99..1e57602 100644
--- a/lib/log.c
+++ b/lib/log.c
@@ -73,7 +73,16 @@ static void libvlc_logf (void *data, int level, const vlc_log_t *item,
         case VLC_MSG_DBG:  level = LIBVLC_DEBUG;   break;
     }
 
-    inst->log.cb (inst->log.data, level, item, fmt, ap);
+    if(level >= inst->log.min_level)
+    {
+        char* msg;
+        int msgSize = vasprintf(&msg, fmt, ap);
+        if (unlikely(msgSize < 0))
+            return;
+
+        inst->log.cb(inst->log.data, level, item, msg);
+        free(msg);
+    }
 }
 
 static const struct vlc_logger_operations libvlc_log_ops = {
@@ -85,28 +94,28 @@ void libvlc_log_unset (libvlc_instance_t *inst)
     vlc_LogSet (inst->p_libvlc_int, NULL, NULL);
 }
 
-void libvlc_log_set (libvlc_instance_t *inst, libvlc_log_cb cb, void *data)
+void libvlc_log_set_preformatted (libvlc_instance_t *p_instance, int min_level, libvlc_log_preformatted_cb cb, void* data )
 {
-    libvlc_log_unset (inst); /* <- Barrier before modifying the callback */
-    inst->log.cb = cb;
-    inst->log.data = data;
-    vlc_LogSet(inst->p_libvlc_int, &libvlc_log_ops, inst);
+    libvlc_log_unset (p_instance); /* <- Barrier before modifying the callback */
+    p_instance->log.cb = cb;
+    p_instance->log.min_level = min_level;
+    p_instance->log.data = data;
+    vlc_LogSet(p_instance->p_libvlc_int, &libvlc_log_ops, p_instance);
 }
 
 /*** Helpers for logging to files ***/
 static void libvlc_log_file (void *data, int level, const libvlc_log_t *log,
-                             const char *fmt, va_list ap)
+                             const char *msg)
 {
     FILE *stream = data;
 
     flockfile (stream);
-    vfprintf (stream, fmt, ap);
-    fputc ('\n', stream);
+    fprintf (stream, "%s\n", msg);
     funlockfile (stream);
     (void) level; (void) log;
 }
 
 void libvlc_log_set_file (libvlc_instance_t *inst, FILE *stream)
 {
-    libvlc_log_set (inst, libvlc_log_file, stream);
+    libvlc_log_set_preformatted (inst, LIBVLC_DEBUG, libvlc_log_file, stream);
 }
-- 
2.20.1