[easytag] Improve TagLib error handling, bug 695453

[David King <davidk src gnome org>]

commit f4c3b3fbacdaf6a4c32b2c39efa88c6fea6926b1
Author: David King <amigadave amigadave com>
Date:   Sun Mar 31 21:37:16 2013 +0100

    Improve TagLib error handling, bug 695453
    
    Avoid dereferencing NULL pointers returned from TagLib when an MP4 file
    could not be read.

 src/mp4_header.c |   12 +++++++++++-
 src/mp4_tag.c    |   37 ++++++++++++++++++++++++++++++++-----
 2 files changed, 43 insertions(+), 6 deletions(-)
---
diff --git a/src/mp4_header.c b/src/mp4_header.c
index 370800c..8bb53d2 100644
--- a/src/mp4_header.c
+++ b/src/mp4_header.c
@@ -70,12 +70,22 @@ gboolean Mp4_Header_Read_File_Info (gchar *filename, ET_File_Info *ETFileInfo)
     if( !taglib_file_is_valid(file) )
     {
         gchar *filename_utf8 = filename_to_display(filename);
-        Log_Print(LOG_ERROR,_("Error while opening file: '%s' (%s)."),filename_utf8,("Contains no audio 
track"));
+        Log_Print (LOG_ERROR, _("File contains no audio track: '%s'"),
+                   filename_utf8);
         g_free(filename_utf8);
         return FALSE;
     }
 
     properties = taglib_file_audioproperties(file);
+    if (properties == NULL)
+    {
+        gchar *filename_utf8 = filename_to_display (filename);
+        Log_Print (LOG_ERROR, _("Error reading properties from file: '%s'"),
+                   filename_utf8);
+        g_free (filename_utf8);
+        taglib_file_free (file);
+        return FALSE;
+    }
 
     /* Get format/subformat */
     {
diff --git a/src/mp4_tag.c b/src/mp4_tag.c
index 738c1d7..a986c3a 100644
--- a/src/mp4_tag.c
+++ b/src/mp4_tag.c
@@ -85,8 +85,27 @@ gboolean Mp4tag_Read_File_Tag (gchar *filename, File_Tag *FileTag)
         return FALSE;
     }
 
-    /* TODO Add error detection */
-    tag = taglib_file_tag(mp4file);
+    /* Check for audio track */
+    if (!taglib_file_is_valid (mp4file))
+    {
+        gchar *filename_utf8 = filename_to_display (filename);
+        Log_Print (LOG_ERROR, _("File contains no audio track: '%s'"),
+                   filename_utf8);
+        g_free (filename_utf8);
+        taglib_file_free (mp4file);
+        return FALSE;
+    }
+
+    tag = taglib_file_tag (mp4file);
+    if (tag == NULL)
+    {
+        gchar *filename_utf8 = filename_to_display (filename);
+        Log_Print (LOG_ERROR, _("Error reading tags from file: '%s'"),
+                   filename_utf8);
+        g_free (filename_utf8);
+        taglib_file_free (mp4file);
+        return FALSE;
+    }
 
     /*********
      * Title *
@@ -173,8 +192,7 @@ gboolean Mp4tag_Write_File_Tag (ET_File *ETFile)
     TagLib_Tag *tag;
     gint error = 0;
 
-    if (!ETFile || !ETFile->FileTag)
-        return FALSE;
+    g_return_val_if_fail (ETFile != NULL || ETFile->FileTag != NULL, FALSE);
 
     FileTag = (File_Tag *)ETFile->FileTag->data;
     filename      = ((File_Name *)ETFile->FileNameCur->data)->value;
@@ -196,7 +214,16 @@ gboolean Mp4tag_Write_File_Tag (ET_File *ETFile)
         return FALSE;
     }
 
-    tag = taglib_file_tag(mp4file);
+    tag = taglib_file_tag (mp4file);
+    if (tag == NULL)
+    {
+        gchar *filename_utf8 = filename_to_display (filename);
+        Log_Print (LOG_ERROR, _("Error reading tags from file: '%s'"),
+                   filename_utf8);
+        g_free (filename_utf8);
+        taglib_file_free (mp4file);
+        return FALSE;
+    }
 
     /*********
      * Title *