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typefinding: detect MSS manifests without using g_convert()

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Embedded systems often have limited charset conversion
functionality, so don't rely on g_convert() (i.e. iconv)
for UTF-16 to UTF-8 conversions, we can easily enough do
that ourselves by converting to native endianness and
then using GLib's helper functions.
This commit is contained in:
Tim-Philipp Müller 2015-04-26 14:27:30 +01:00
parent 7e8e020cfd
commit 9ef16721ed
1 changed files with 68 additions and 48 deletions
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116
gst/typefind/gsttypefindfunctions.c
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@ -3555,63 +3555,83 @@ swf_type_find (GstTypeFind * tf, gpointer unused)
/*** application/vnd.ms-sstr+xml ***/
static void
mss_manifest_load_utf16 (gunichar2 * utf16_ne, const guint8 * utf16_data,
gsize data_size, guint data_endianness)
{
memcpy (utf16_ne, utf16_data, data_size);
if (data_endianness != G_BYTE_ORDER) {
guint i;
for (i = 0; i < data_size / 2; ++i)
utf16_ne[i] = GUINT16_SWAP_LE_BE (utf16_ne[i]);
}
}
static GstStaticCaps mss_manifest_caps =
GST_STATIC_CAPS ("application/vnd.ms-sstr+xml");
#define MSS_MANIFEST_CAPS (gst_static_caps_get(&mss_manifest_caps))
static void
mss_manifest_type_find (GstTypeFind * tf, gpointer unused)
{
gunichar2 utf16_ne[512];
const guint8 *data;
guint data_endianness = 0;
glong n_read = 0, size = 0;
guint length;
gchar *utf8;
if (xml_check_first_element (tf, "SmoothStreamingMedia", 20, TRUE)) {
gst_type_find_suggest (tf, GST_TYPE_FIND_MAXIMUM, MSS_MANIFEST_CAPS);
} else {
const guint8 *data;
gboolean utf16_le, utf16_be;
const gchar *convert_from = NULL;
guint8 *converted_data;
/* try detecting the charset */
data = gst_type_find_peek (tf, 0, 2);
if (data == NULL)
return;
/* look for a possible BOM */
utf16_le = data[0] == 0xFF && data[1] == 0xFE;
utf16_be = data[0] == 0xFE && data[1] == 0xFF;
if (utf16_le) {
convert_from = "UTF-16LE";
} else if (utf16_be) {
convert_from = "UTF-16BE";
}
if (convert_from) {
gsize new_size = 0;
guint length = gst_type_find_get_length (tf);
/* try a default that should be enough */
if (length == 0)
length = 512;
data = gst_type_find_peek (tf, 0, length);
if (data) {
/* skip the BOM */
data += 2;
length -= 2;
converted_data =
(guint8 *) g_convert ((gchar *) data, length, "UTF-8", convert_from,
NULL, &new_size, NULL);
if (converted_data) {
if (xml_check_first_element_from_data (converted_data, new_size,
"SmoothStreamingMedia", 20, TRUE))
gst_type_find_suggest (tf, GST_TYPE_FIND_MAXIMUM,
MSS_MANIFEST_CAPS);
g_free (converted_data);
}
}
}
return;
}
length = gst_type_find_get_length (tf);
/* try detecting the charset */
data = gst_type_find_peek (tf, 0, 2);
if (data == NULL)
return;
/* look for a possible BOM */
if (data[0] == 0xFF && data[1] == 0xFE)
data_endianness = G_LITTLE_ENDIAN;
else if (data[0] == 0xFE && data[1] == 0xFF)
data_endianness = G_BIG_ENDIAN;
else
return;
/* try a default that should be enough */
if (length == 0)
length = 512;
else if (length < 64)
return;
/* FIXME: we probably don't need or want the entire thing.. */
data = gst_type_find_peek (tf, 0, length);
if (data == NULL)
return;
/* skip the BOM */
data += 2;
length -= 2;
length = GST_ROUND_DOWN_2 (length);
/* convert to native endian UTF-16 */
mss_manifest_load_utf16 (utf16_ne, data, length, data_endianness);
/* and now convert to UTF-8 */
utf8 = g_utf16_to_utf8 (utf16_ne, length / 2, &n_read, &size, NULL);
if (utf8 != NULL && n_read > 0) {
if (xml_check_first_element_from_data ((const guint8 *) utf8, size,
"SmoothStreamingMedia", 20, TRUE))
gst_type_find_suggest (tf, GST_TYPE_FIND_MAXIMUM, MSS_MANIFEST_CAPS);
}
g_free (utf8);
}
/*** image/jpeg ***/