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// SPDX-License-Identifier: GPL-2.0
#include "metadata.h"
#include "exif.h"
#include "qthelper.h"
#include <QString>
#include <QFile>
#include <QDateTime>
// Weirdly, android builds fail owing to undefined UINT64_MAX
#ifndef UINT64_MAX
#define UINT64_MAX (~0ULL)
#endif
// The following two functions fetch an arbitrary-length _unsigned_ integer from either
// a file or a memory location in big-endian mode. The size of the integer is passed
// via a template argument [e.g. getBE<uint16_t>(...)].
// The function doing file access returns a default value on IO error or end-of-file.
// Warning: This code works properly only for unsigned integers. The template parameter
// is not checked and passing a signed integer will silently fail!
template <typename T>
static inline T getBE(const char *buf_in)
{
constexpr size_t size = sizeof(T);
// Interpret raw bytes as unsigned char to avoid sign extension for
// characters in the 0x80...0xff range.
auto buf = (unsigned const char *)buf_in;
T ret = 0;
for (size_t i = 0; i < size; ++i)
ret = (ret << 8) | buf[i];
return ret;
}
template <typename T>
static inline T getBE(QFile &f, T def=0)
{
constexpr size_t size = sizeof(T);
char buf[size];
if (f.read(buf, size) != size)
return def;
return getBE<T>(buf);
}
static bool parseExif(QFile &f, struct metadata *metadata)
{
f.seek(0);
if (getBE<uint16_t>(f) != 0xffd8)
return false;
for (;;) {
switch (getBE<uint16_t>(f)) {
case 0xffc0:
case 0xffc2:
case 0xffc4:
case 0xffd0 ... 0xffd7:
case 0xffdb:
case 0xffdd:
case 0xffe0:
case 0xffe2 ... 0xffef:
case 0xfffe: {
uint16_t len = getBE<uint16_t>(f);
if (len < 2)
return false;
f.seek(f.pos() + len - 2); // TODO: switch to QFile::skip()
break;
}
case 0xffe1: {
uint16_t len = getBE<uint16_t>(f);
if (len < 2)
return false;
len -= 2;
QByteArray data = f.read(len);
if (data.size() != len)
return false;
easyexif::EXIFInfo exif;
if (exif.parseFromEXIFSegment(reinterpret_cast<const unsigned char *>(data.constData()), len) != PARSE_EXIF_SUCCESS)
return false;
metadata->longitude.udeg = lrint(1000000.0 * exif.GeoLocation.Longitude);
metadata->latitude.udeg = lrint(1000000.0 * exif.GeoLocation.Latitude);
metadata->timestamp = exif.epoch();
return true;
}
case 0xffda:
case 0xffd9:
// We expect EXIF data before any scan data
return false;
default:
return false;
}
}
}
static bool parseMP4(QFile &f, metadata *metadata)
{
f.seek(0);
// MP4s and related formats are hierarchical, being made up of "atoms", which can
// contain other atoms (an interesting interpretation of the term atom).
// To parse the file, the remaining to-be-parsed bytes of the upper atoms in
// the parse-tree are tracked in a stack-like structure. This is not strictly
// necessary, since the level at which an atom is found is insubstantial.
// Nevertheless, it is an effective and simple way of sanity-checking the file and the
// parsing routine.
std::vector<uint64_t> atom_stack;
atom_stack.reserve(10);
// For the outmost level, set the atom-size the the maximum value representable in
// 64-bits, which effectively means parse to the end of file.
atom_stack.push_back(UINT64_MAX);
// The first atom of an MP4 or related video is supposed to be of the "ftyp" kind.
// If such an atom is found as first atom, this function will return true, indicating
// that the file is a video.
bool found_ftyp = false;
while (!f.atEnd() && !atom_stack.empty()) {
// Parse atom header. The header can have two forms (each character stands for a byte):
// lllltttt
// or
// 0001ttttllllllll
// where "l" stands for length in big-endian mode and "t" for type of the atom.
// The length includes the 8- or 16-bytes header.
uint64_t atom_size = getBE<uint32_t>(f, 2);
int atom_header_size = 8;
if (atom_size > 1 && atom_size < 8)
break;
char type[4];
if (f.read(type, 4) != 4)
break;
if (atom_size == 1) {
atom_size = getBE<uint64_t>(f);
atom_header_size = 16;
if (atom_size < 16)
break;
}
if (atom_size == 0)
atom_size = atom_stack.back();
if (atom_size > atom_stack.back())
break;
atom_stack.back() -= atom_size;
atom_size -= atom_header_size;
// The first atom must be "ftyp"
if (!found_ftyp) {
found_ftyp = !memcmp(type, "ftyp", 4);
if (!found_ftyp)
break;
}
if (!memcmp(type, "moov", 4) ||
!memcmp(type, "trak", 4) ||
!memcmp(type, "mdia", 4)) {
// Recurse into "moov", "trak" and "mdia" atoms
atom_stack.push_back(atom_size);
continue;
} else if (!memcmp(type, "mdhd", 4) && atom_size >= 24 && atom_size < 4096) {
// Parse "mdhd" (media header).
// Sanity check: size between 24 and 4096
std::vector<char> data(atom_size);
if (f.read(&data[0], atom_size) != static_cast<int>(atom_size))
break;
uint64_t timestamp = 0;
// First byte is version. We know version 0 and 1
switch (data[0]) {
case 0:
timestamp = getBE<uint32_t>(&data[4]);
break;
case 1:
timestamp = getBE<uint64_t>(&data[4]);
break;
default:
// For unknown versions: ignore -> maybe we find a parseable "mdhd" atom later in this file
break;
}
// Timestamp is given as seconds since midnight 1904/1/1. To be convertible to the UNIX epoch
// it must be larger than 2082844800.
if (timestamp >= 2082844800) {
metadata->timestamp = timestamp - 2082844800;
// Currently, we only know how to extract timestamps, so we might just quit parsing here.
break;
}
} else {
// Jump over unknown atom
if (!f.seek(f.pos() + atom_size)) // TODO: switch to QFile::skip()
break;
}
// If end of atom is reached, return to outer atom
while (!atom_stack.empty() && atom_stack.back() == 0)
atom_stack.pop_back();
}
return found_ftyp;
}
extern "C" mediatype_t get_metadata(const char *filename_in, metadata *data)
{
data->timestamp = 0;
data->latitude.udeg = 0;
data->longitude.udeg = 0;
QString filename = localFilePath(QString(filename_in));
QFile f(filename);
if (!f.open(QIODevice::ReadOnly))
return MEDIATYPE_IO_ERROR;
if (parseExif(f, data)) {
return MEDIATYPE_PICTURE;
} else if(parseMP4(f, data)) {
return MEDIATYPE_VIDEO;
} else {
// If we couldn't parse EXIF or MP4 data, use file creation date.
// TODO: QFileInfo::created is deprecated in newer Qt versions.
data->timestamp = QFileInfo(filename).created().toMSecsSinceEpoch() / 1000;
return MEDIATYPE_UNKNOWN;
}
}
extern "C" timestamp_t picture_get_timestamp(const char *filename)
{
struct metadata data;
get_metadata(filename, &data);
return data.timestamp;
}
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