[gdk-pixbuf] jpeg: Add support for JPEG_COM EXIF tag

[Bastien Nocera <hadess src gnome org>]

commit 47c587bf5fe5d62197e0ab2b26a5d93f434cade1
Author: Pawel Piatek <xj wp pl>
Date:   Mon Mar 13 22:51:34 2017 +0100

    jpeg: Add support for JPEG_COM EXIF tag
    
    https://bugzilla.gnome.org/show_bug.cgi?id=143608

 gdk-pixbuf/gdk-pixbuf.c     |    2 ++
 gdk-pixbuf/io-jpeg.c        |   31 +++++++++++++++++++++++++++++++
 tests/bug143608-comment.jpg |  Bin 0 -> 191869 bytes
 tests/pixbuf-jpeg.c         |   20 ++++++++++++++++++++
 4 files changed, 53 insertions(+), 0 deletions(-)
---
diff --git a/gdk-pixbuf/gdk-pixbuf.c b/gdk-pixbuf/gdk-pixbuf.c
index d7b78e4..fb146ba 100644
--- a/gdk-pixbuf/gdk-pixbuf.c
+++ b/gdk-pixbuf/gdk-pixbuf.c
@@ -909,6 +909,8 @@ gdk_pixbuf_fill (GdkPixbuf *pixbuf,
  * the "multipage" option string to "yes" when a multi-page TIFF is loaded.
  * Since 2.32 the JPEG and PNG loaders set "x-dpi" and "y-dpi" if the file
  * contains image density information in dots per inch.
+ * Since 2.36.6, the JPEG loader sets the "comment" option with the comment
+ * EXIF tag.
  * 
  * Return value: the value associated with @key. This is a nul-terminated 
  * string that should not be freed or %NULL if @key was not found.
diff --git a/gdk-pixbuf/io-jpeg.c b/gdk-pixbuf/io-jpeg.c
index 92ec36b..dd88a35 100644
--- a/gdk-pixbuf/io-jpeg.c
+++ b/gdk-pixbuf/io-jpeg.c
@@ -525,6 +525,21 @@ jpeg_parse_exif (JpegExifContext *context, j_decompress_ptr cinfo)
        }
 }
 
+static gchar *
+jpeg_get_comment (j_decompress_ptr cinfo)
+{
+       jpeg_saved_marker_ptr cmarker;
+
+       cmarker = cinfo->marker_list;
+       while (cmarker != NULL) {
+               if (cmarker->marker == JPEG_COM)
+                       return g_strndup ((const gchar *) cmarker->data, cmarker->data_length);
+               cmarker = cmarker->next;
+       }
+
+       return NULL;
+}
+
 static void
 jpeg_destroy_exif_context (JpegExifContext *context)
 {
@@ -550,6 +565,7 @@ gdk_pixbuf__jpeg_image_load (FILE *f, GError **error)
        struct error_handler_data jerr;
        stdio_src_ptr src;
        gchar *icc_profile_base64;
+       gchar *comment;
        JpegExifContext exif_context = { 0, };
 
        /* setup error handler */
@@ -592,6 +608,7 @@ gdk_pixbuf__jpeg_image_load (FILE *f, GError **error)
 
        jpeg_save_markers (&cinfo, JPEG_APP0+1, 0xffff);
        jpeg_save_markers (&cinfo, JPEG_APP0+2, 0xffff);
+       jpeg_save_markers (&cinfo, JPEG_COM, 0xffff);
        jpeg_read_header (&cinfo, TRUE);
 
        /* parse exif data */
@@ -619,6 +636,12 @@ gdk_pixbuf__jpeg_image_load (FILE *f, GError **error)
                goto out; 
        }
 
+       comment = jpeg_get_comment (&cinfo);
+       if (comment != NULL) {
+               gdk_pixbuf_set_option (pixbuf, "comment", comment);
+               g_free (comment);
+       }
+
        switch (cinfo.density_unit) {
        case 1:
                /* Dots per inch (no conversion required) */
@@ -1027,9 +1050,11 @@ gdk_pixbuf__jpeg_image_load_increment (gpointer data,
                /* try to load jpeg header */
                if (!context->got_header) {
                        int rc;
+                       gchar* comment;
                
                        jpeg_save_markers (cinfo, JPEG_APP0+1, 0xffff);
                        jpeg_save_markers (cinfo, JPEG_APP0+2, 0xffff);
+                       jpeg_save_markers (cinfo, JPEG_COM, 0xffff);
                        rc = jpeg_read_header (cinfo, TRUE);
                        context->src_initialized = TRUE;
                        
@@ -1080,6 +1105,12 @@ gdk_pixbuf__jpeg_image_load_increment (gpointer data,
                                goto out;
                        }
 
+                       comment = jpeg_get_comment (cinfo);
+                       if (comment != NULL) {
+                               gdk_pixbuf_set_option (context->pixbuf, "comment", comment);
+                               g_free (comment);
+                       }
+
                        switch (cinfo->density_unit) {
                        case 1:
                                /* Dots per inch (no conversion required) */
diff --git a/tests/bug143608-comment.jpg b/tests/bug143608-comment.jpg
new file mode 100644
index 0000000..7c3c93a
Binary files /dev/null and b/tests/bug143608-comment.jpg differ
diff --git a/tests/pixbuf-jpeg.c b/tests/pixbuf-jpeg.c
index 073104a..ea1d62e 100644
--- a/tests/pixbuf-jpeg.c
+++ b/tests/pixbuf-jpeg.c
@@ -96,6 +96,25 @@ test_bug_775218 (void)
   g_clear_object (&ref);
 }
 
+static void
+test_comment(void)
+{
+  GError *error = NULL;
+  GdkPixbuf *ref;
+
+  if (!format_supported ("jpeg") || !format_supported ("png"))
+    {
+      g_test_skip ("format not supported");
+      return;
+    }
+
+  ref = gdk_pixbuf_new_from_file (g_test_get_filename (G_TEST_DIST, "bug143608-comment.jpg", NULL), &error);
+  g_assert_no_error (error);
+
+  g_assert_cmpstr (gdk_pixbuf_get_option (ref, "comment"), ==, "COMMENT HERE");
+  g_object_unref (ref);
+}
+
 int
 main (int argc, char **argv)
 {
@@ -104,6 +123,7 @@ main (int argc, char **argv)
   g_test_add_func ("/pixbuf/jpeg/inverted_cmyk_jpeg", test_inverted_cmyk_jpeg);
   g_test_add_func ("/pixbuf/jpeg/type9_rotation_exif_tag", test_type9_rotation_exif_tag);
   g_test_add_func ("/pixbuf/jpeg/bug775218", test_bug_775218);
+  g_test_add_func ("/pixbuf/jpeg/comment", test_comment);
 
   return g_test_run ();
 }