// Returns true on success. The caller must use MetadataFree() on 'metadata' in
// all cases.
static int ExtractMetadataFromTIFF(TIFF* const tif, Metadata* const metadata) {
int i;
toff_t exif_ifd_offset;
for (i = 0; kTIFFMetadataMap[i].tag != 0; ++i) {
MetadataPayload* const payload =
(MetadataPayload*)((uint8_t*)metadata +
kTIFFMetadataMap[i].storage_offset);
void* tag_data;
uint32 tag_data_len;
if (TIFFGetField(tif, kTIFFMetadataMap[i].tag, &tag_data_len, &tag_data) &&
!MetadataCopy((const char*)tag_data, tag_data_len, payload)) {
return 0;
}
}
// TODO(jzern): To extract the raw EXIF directory some parsing of it would be
// necessary to determine the overall size. In addition, value offsets in
// individual directory entries may need to be updated as, depending on the
// type, they are file based.
// Exif 2.2 Section 4.6.2 Tag Structure
// TIFF Revision 6.0 Part 1 Section 2 TIFF Structure #Image File Directory
if (TIFFGetField(tif, TIFFTAG_EXIFIFD, &exif_ifd_offset)) {
fprintf(stderr, "Warning: EXIF extraction from TIFF is unsupported.\n");
}
return 1;
}
// Returns true on success and false for memory errors and corrupt profiles.
// The caller must use MetadataFree() on 'metadata' in all cases.
static int ExtractMetadataFromJPEG(j_decompress_ptr dinfo,
Metadata* const metadata) {
static const struct {
int marker;
const char* signature;
size_t signature_length;
size_t storage_offset;
} kJPEGMetadataMap[] = {
// Exif 2.2 Section 4.7.2 Interoperability Structure of APP1 ...
{ JPEG_APP1, "Exif\0", 6, METADATA_OFFSET(exif) },
// XMP Specification Part 3 Section 3 Embedding XMP Metadata ... #JPEG
// TODO(jzern) Add support for 'ExtendedXMP'
{ JPEG_APP1, "http://ns.adobe.com/xap/1.0/", 29, METADATA_OFFSET(xmp) },
{ 0, NULL, 0, 0 },
};
jpeg_saved_marker_ptr marker;
// Treat ICC profiles separately as they may be segmented and out of order.
if (!StoreICCP(dinfo, &metadata->iccp)) return 0;
for (marker = dinfo->marker_list; marker != NULL; marker = marker->next) {
int i;
for (i = 0; kJPEGMetadataMap[i].marker != 0; ++i) {
if (marker->marker == kJPEGMetadataMap[i].marker &&
marker->data_length > kJPEGMetadataMap[i].signature_length &&
!memcmp(marker->data, kJPEGMetadataMap[i].signature,
kJPEGMetadataMap[i].signature_length)) {
MetadataPayload* const payload =
(MetadataPayload*)((uint8_t*)metadata +
kJPEGMetadataMap[i].storage_offset);
if (payload->bytes == NULL) {
const char* marker_data = (const char*)marker->data +
kJPEGMetadataMap[i].signature_length;
const size_t marker_data_length =
marker->data_length - kJPEGMetadataMap[i].signature_length;
if (!MetadataCopy(marker_data, marker_data_length, payload)) return 0;
} else {
fprintf(stderr, "Ignoring additional '%s' marker\n",
kJPEGMetadataMap[i].signature);
}
}
}
}
return 1;
}
// Looks for metadata at both the beginning and end of the PNG file, giving
// preference to the head.
// Returns true on success. The caller must use MetadataFree() on 'metadata' in
// all cases.
static int ExtractMetadataFromPNG(png_structp png,
png_infop const head_info,
png_infop const end_info,
Metadata* const metadata) {
int p;
for (p = 0; p < 2; ++p) {
png_infop const info = (p == 0) ? head_info : end_info;
png_textp text = NULL;
const png_uint_32 num = png_get_text(png, info, &text, NULL);
png_uint_32 i;
// Look for EXIF / XMP metadata.
for (i = 0; i < num; ++i, ++text) {
int j;
for (j = 0; kPNGMetadataMap[j].name != NULL; ++j) {
if (!strcmp(text->key, kPNGMetadataMap[j].name)) {
MetadataPayload* const payload =
(MetadataPayload*)((uint8_t*)metadata +
kPNGMetadataMap[j].storage_offset);
png_size_t text_length;
switch (text->compression) {
#ifdef PNG_iTXt_SUPPORTED
case PNG_ITXT_COMPRESSION_NONE:
case PNG_ITXT_COMPRESSION_zTXt:
text_length = text->itxt_length;
break;
#endif
case PNG_TEXT_COMPRESSION_NONE:
case PNG_TEXT_COMPRESSION_zTXt:
default:
text_length = text->text_length;
break;
}
if (payload->bytes != NULL) {
fprintf(stderr, "Ignoring additional '%s'\n", text->key);
} else if (!kPNGMetadataMap[j].process(text->text, text_length,
payload)) {
fprintf(stderr, "Failed to process: '%s'\n", text->key);
return 0;
}
break;
}
}
}
// Look for an ICC profile.
{
png_charp name;
int comp_type;
#if LOCAL_PNG_PREREQ(1,5)
png_bytep profile;
#else
png_charp profile;
#endif
png_uint_32 len;
if (png_get_iCCP(png, info,
&name, &comp_type, &profile, &len) == PNG_INFO_iCCP) {
if (!MetadataCopy((const char*)profile, len, &metadata->iccp)) return 0;
}
}
}
return 1;
}