printf: add infrastructure for pointer extensions hook

Does not do anything yet. On a sidenote, we can't just use
%p\001 or so to signal the extension because g-i complains
about an invalid ascii character then, so have to resort to
something more elaborate, such as %p\aA etc.

https://bugzilla.gnome.org/show_bug.cgi?id=613081

gst/gstinfo.c

@@ -127,6 +127,10 @@
 
 /* our own printf implementation with custom extensions to %p for caps etc. */
 #include "printf/printf.h"
+#include "printf/printf-extension.h"
+
+static char *gst_info_printf_pointer_extension_func (const char *format,
+    void *ptr);
 
 #endif /* !GST_DISABLE_GST_DEBUG */
 
@@ -223,13 +227,6 @@ dladdr (void *address, Dl_info * dl)
 static void gst_debug_reset_threshold (gpointer category, gpointer unused);
 static void gst_debug_reset_all_thresholds (void);
 
-#if 0
-static int _gst_info_printf_extension_ptr (FILE * stream,
-    const struct printf_info *info, const void *const *args);
-static int _gst_info_printf_extension_segment (FILE * stream,
-    const struct printf_info *info, const void *const *args);
-#endif
-
 struct _GstDebugMessage
 {
   gchar *message;
@@ -328,12 +325,8 @@ _priv_gst_debug_init (void)
   /* get time we started for debugging messages */
   _priv_gst_info_start_time = gst_util_get_timestamp ();
 
-#if 0
-  register_printf_specifier (GST_PTR_FORMAT[0], _gst_info_printf_extension_ptr,
-      NULL);
-  register_printf_specifier (GST_SEGMENT_FORMAT[0],
-      _gst_info_printf_extension_segment, NULL);
-#endif
+  __gst_printf_pointer_extension_set_func
+      (gst_info_printf_pointer_extension_func);
 
   /* do NOT use a single debug function before this line has been run */
   GST_CAT_DEFAULT = _gst_debug_category_new ("default",
@@ -734,7 +727,6 @@ gst_debug_print_object (gpointer ptr)
   return g_strdup_printf ("%p", ptr);
 }
 
-#if 0
 static gchar *
 gst_debug_print_segment (gpointer ptr)
 {
@@ -775,7 +767,31 @@ gst_debug_print_segment (gpointer ptr)
     }
   }
 }
-#endif
+
+static char *
+gst_info_printf_pointer_extension_func (const char *format, void *ptr)
+{
+  char *s = NULL;
+
+  if (format[0] == 'p' && format[1] == '\a') {
+    switch (format[2]) {
+      case 'A':                /* GST_PTR_FORMAT     */
+        s = gst_debug_print_object (ptr);
+        break;
+      case 'B':                /* GST_SEGMENT_FORMAT */
+        s = gst_debug_print_segment (ptr);
+        break;
+      default:
+        /* must have been compiled against a newer version with an extension
+         * we don't known about yet - just ignore and fallback to %p below */
+        break;
+    }
+  }
+  if (s == NULL)
+    s = g_strdup_printf ("%p", ptr);
+
+  return s;
+}
 
 /**
  * gst_debug_construct_term_color:
@@ -1775,48 +1791,6 @@ _gst_debug_register_funcptr (GstDebugFuncPtr func, const gchar * ptrname)
   g_mutex_unlock (&__dbg_functions_mutex);
 }
 
-/*** PRINTF EXTENSIONS ********************************************************/
-
-#if 0
-static int
-_gst_info_printf_extension_ptr (FILE * stream, const struct printf_info *info,
-    const void *const *args)
-{
-  char *buffer;
-  int len;
-  void *ptr;
-
-  buffer = NULL;
-  ptr = *(void **) args[0];
-
-  buffer = gst_debug_print_object (ptr);
-  len = fprintf (stream, "%*s", (info->left ? -info->width : info->width),
-      buffer);
-
-  g_free (buffer);
-  return len;
-}
-
-static int
-_gst_info_printf_extension_segment (FILE * stream,
-    const struct printf_info *info, const void *const *args)
-{
-  char *buffer;
-  int len;
-  void *ptr;
-
-  buffer = NULL;
-  ptr = *(void **) args[0];
-
-  buffer = gst_debug_print_segment (ptr);
-  len = fprintf (stream, "%*s", (info->left ? -info->width : info->width),
-      buffer);
-
-  g_free (buffer);
-  return len;
-}
-#endif
-
 static void
 gst_info_dump_mem_line (gchar * linebuf, gsize linebuf_size,
     const guint8 * mem, gsize mem_offset, gsize mem_size)

gst/gstinfo.h

@@ -235,7 +235,7 @@ struct _GstDebugCategory {
  * printf format type used to debug GStreamer types.
  * This can only be used on types whose size is >= sizeof(gpointer).
  */
-#define GST_PTR_FORMAT "p" /* FIXME: add suffix for differentiation */
+#define GST_PTR_FORMAT     "p\aA"
 
 /**
  * GST_SEGMENT_FORMAT:
@@ -243,7 +243,7 @@ struct _GstDebugCategory {
  * printf format type used to debug GStreamer segments.
  * This can only be used on pointers to GstSegment structures.
  */
-#define GST_SEGMENT_FORMAT "p" /* FIXME: add suffix for differentiation */
+#define GST_SEGMENT_FORMAT "p\aB"
 
 typedef struct _GstDebugMessage GstDebugMessage;
 

gst/printf/Makefile.am

@@ -13,6 +13,8 @@ libgstprintf_la_SOURCES = 	\
 	vasnprintf.h \
 	printf.c \
 	printf.h \
+	printf-extension.c \
+	printf-extension.h \
 	gst-printf.h
 
 EXTRA_DIST = README

gst/printf/README

@@ -50,7 +50,8 @@ __gst_printf namespace for GStreamer. Also #define HAVE_SNPRINTF 0 has
 been changed to #undef HAVE_SNPRINTF, and HAVE_ALLOCA has been changed to
 GLIB_HAVE_ALLOCA_H
 
-We will also add support for our custom printf format specifiers.
+printf-extension.[ch] were added to provide support for custom pointer
+arguments (e.g. caps, events, etc.)
 
 Files have also been indented with gst-indent, so this is basically a
 permanent fork and any patches will have to be merged manually.

gst/printf/printf-extension.c

@@ -0,0 +1,50 @@
+/* GStreamer printf extension hooks
+ * Copyright (C) 2013 Tim-Philipp Müller <tim centricular net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "printf-extension.h"
+#include "gst-printf.h"
+#include <stdio.h>
+#include <string.h>
+
+static PrintfPointerExtensionFunc ptr_ext_func; /* NULL */
+
+void
+__gst_printf_pointer_extension_set_func (PrintfPointerExtensionFunc func)
+{
+  /* since this is internal, we don't need to worry about thread-safety */
+  ptr_ext_func = func;
+}
+
+char *
+__gst_printf_pointer_extension_serialize (const char *format, void *ptr)
+{
+  char *buf;
+
+  if (ptr_ext_func == NULL) {
+    buf = malloc (32);
+    memset (buf, 0, 32);
+    sprintf (buf, "%p", ptr);
+  } else {
+    /* note: we map malloc/free to g_malloc/g_free in gst-printf.h, so the
+     * fact that gstinfo gives us a glib-allocated string and the printf
+     * routines free it with free() and not g_free() should not be a problem */
+    buf = ptr_ext_func (format, ptr);
+  }
+  return buf;
+}

gst/printf/printf-extension.h

@@ -0,0 +1,31 @@
+/* GStreamer printf extension hooks
+ * Copyright (C) 2013 Tim-Philipp Müller <tim centricular net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#ifndef __GST_PRINTF_EXTENSION_H_INCLUDED__
+#define __GST_PRINTF_EXTENSION_H_INCLUDED__
+
+typedef char * (*PrintfPointerExtensionFunc) (const char * format, void * ptr);
+
+/* we only need one global function, since it's only GstInfo registering extensions */
+void   __gst_printf_pointer_extension_set_func  (PrintfPointerExtensionFunc func);
+
+/* functions for internal printf implementation to handle the extensions */
+char * __gst_printf_pointer_extension_serialize (const char * format, void * ptr);
+
+#endif /* __GST_PRINTF_EXTENSION_H_INCLUDED__ */