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jpeg2000: valid_file implementation, much faster than trying to open #4548

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Dec 1, 2024
Merged

jpeg2000: valid_file implementation, much faster than trying to open #4548

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50 changes: 30 additions & 20 deletions src/jpeg2000.imageio/jpeg2000input.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,6 +80,7 @@ class Jpeg2000Input final : public ImageInput {
return feature == "ioproxy";
// FIXME: we should support Exif/IPTC, but currently don't.
}
bool valid_file(Filesystem::IOProxy* ioproxy) const override;
bool open(const std::string& name, ImageSpec& spec) override;
bool open(const std::string& name, ImageSpec& newspec,
const ImageSpec& config) override;
Expand All @@ -97,7 +98,8 @@ class Jpeg2000Input final : public ImageInput {

void init(void);

bool isJp2File(const int* const p_magicTable) const;
static bool is_jp2_header(const uint8_t header[12]);
static bool is_j2k_header(const uint8_t header[5]);

opj_codec_t* create_decompressor();
void destroy_decompressor();
Expand Down Expand Up @@ -208,7 +210,19 @@ Jpeg2000Input::init(void)
ioproxy_clear();
}

bool
Jpeg2000Input::valid_file(Filesystem::IOProxy* ioproxy) const
{
if (!ioproxy || ioproxy->mode() != Filesystem::IOProxy::Mode::Read)
return false;

uint8_t header[12];
auto r = ioproxy->pread(header, sizeof(header), 0);
if (r != sizeof(header)) {
return false;
}
return is_jp2_header(header) || is_j2k_header(header);
}

bool
Jpeg2000Input::open(const std::string& name, ImageSpec& p_spec)
Expand Down Expand Up @@ -409,36 +423,32 @@ Jpeg2000Input::close(void)
return true;
}


bool
Jpeg2000Input::isJp2File(const int* const p_magicTable) const
Jpeg2000Input::is_jp2_header(const uint8_t header[12])
{
const int32_t JP2_MAGIC = 0x0000000C, JP2_MAGIC2 = 0x0C000000;
if (p_magicTable[0] == JP2_MAGIC || p_magicTable[0] == JP2_MAGIC2) {
const int32_t JP2_SIG1_MAGIC = 0x6A502020, JP2_SIG1_MAGIC2 = 0x2020506A;
const int32_t JP2_SIG2_MAGIC = 0x0D0A870A, JP2_SIG2_MAGIC2 = 0x0A870A0D;
if ((p_magicTable[1] == JP2_SIG1_MAGIC
|| p_magicTable[1] == JP2_SIG1_MAGIC2)
&& (p_magicTable[2] == JP2_SIG2_MAGIC
|| p_magicTable[2] == JP2_SIG2_MAGIC2)) {
return true;
}
}
return false;
const uint8_t jp2_header[] = { 0x0, 0x0, 0x0, 0x0C, 0x6A, 0x50,
0x20, 0x20, 0x0D, 0x0A, 0x87, 0x0A };
return memcmp(header, jp2_header, sizeof(jp2_header)) == 0;
}

bool
Jpeg2000Input::is_j2k_header(const uint8_t header[5])
{
const uint8_t j2k_header[] = { 0xFF, 0x4F, 0xFF, 0x51, 0x00 };
return memcmp(header, j2k_header, sizeof(j2k_header)) == 0;
}

opj_codec_t*
Jpeg2000Input::create_decompressor()
{
int magic[3];
auto r = ioproxy()->pread(magic, sizeof(magic), 0);
if (r != 3 * sizeof(int)) {
uint8_t header[12];
auto r = ioproxy()->pread(header, sizeof(header), 0);
if (r != sizeof(header)) {
errorfmt("Empty file \"{}\"", m_filename);
return nullptr;
}
return opj_create_decompress(isJp2File(magic) ? OPJ_CODEC_JP2
: OPJ_CODEC_J2K);
return opj_create_decompress(is_jp2_header(header) ? OPJ_CODEC_JP2
: OPJ_CODEC_J2K);
}


Expand Down
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