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made error handling better

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This commit is contained in:
Luna 2025-07-24 03:01:02 +02:00
parent eb5c0e5ab5
commit c62f43c931
5 changed files with 39 additions and 17 deletions
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39
src/lily_png.cpp
View file

@ -3,7 +3,7 @@
std::vector<lily_png::color_rgb> palette;
bool palette_found = false;
static void read_raw_data(const std::string &file_path, file_reader::buffer<unsigned char> &data, lily_png::metadata &meta)
static std::expected<bool, lily_png::png_error> read_raw_data(const std::string &file_path, file_reader::buffer<unsigned char> &data, lily_png::metadata &meta)
{
std::println("Zlib version is {}", zlibVersion());
unsigned char magic[9] = {137, 80, 78, 71, 13, 10, 26, 10};
@ -11,26 +11,30 @@ static void read_raw_data(const std::string &file_path, file_reader::buffer<unsi
char file_magic[9] = {0};
auto res = reader.read_buffer(file_magic, 8).or_else([](const file_reader::RESULT &res)
{
std::println("Reading failed!");
std::println("Reading magic failed!");
return std::expected<size_t, file_reader::RESULT>{0};
});
if (res.value() == 0)
throw std::runtime_error("Read failed");
return std::unexpected(lily_png::png_error::read_failed);
if (memcmp(magic, file_magic, 8) != 0)
{
std::println("File is not a png!");
return ;
return std::unexpected(lily_png::png_error::file_is_not_a_png);
}
file_reader::buffer<unsigned char> raw_dat{};
while (true)
{
std::tuple<unsigned int, file_reader::buffer<char>> chunk_header;
std::get<1>(chunk_header).size = 4;
auto ret = reader.read_from_tuple(chunk_header);
if (!ret || ret.value() != 8)
auto ret = reader.read_from_tuple(chunk_header).or_else([](const file_reader::RESULT &res)
{
std::println("Reading header failed!");
return std::expected<size_t, file_reader::RESULT>{0};
});
if (ret.value() != 8)
{
std::println("Chunk incomplete!");
return ;
return std::unexpected(lily_png::png_error::read_failed);
}
unsigned int size = std::get<0>(chunk_header);
//std::println("Chunk type {} Size {}", std::get<1>(chunk_header).data, std::get<0>(chunk_header));
@ -39,11 +43,15 @@ static void read_raw_data(const std::string &file_path, file_reader::buffer<unsi
raw_data.size = std::get<0>(chunk_header);
std::tuple<file_reader::buffer<char>, unsigned> dat;
std::get<0>(dat).size = std::get<0>(chunk_header);
ret = reader.read_from_tuple(dat);
if (!ret || ret.value() != raw_data.size + 4)
ret = reader.read_from_tuple(dat).or_else([](const file_reader::RESULT &res)
{
std::println("Reading data failed!");
return std::expected<size_t, file_reader::RESULT>{0};
});
if (ret.value() != raw_data.size + 4)
{
std::println("Chunk incomplete!");
return ;
return std::unexpected(lily_png::png_error::read_failed);
}
unsigned long crc = crc32(0, reinterpret_cast<unsigned char *>(std::get<1>(chunk_header).data), 4);
crc = crc32(crc, reinterpret_cast<unsigned char *>(std::get<0>(dat).data), std::get<0>(chunk_header));
@ -65,7 +73,7 @@ static void read_raw_data(const std::string &file_path, file_reader::buffer<unsi
if (size%3 != 0)
{
std::println("Palette size is not divisible by 3");
return ;
return std::unexpected(lily_png::png_error::read_failed);
}
for (int i = 0; i < size; i += 3)
{
@ -88,6 +96,7 @@ static void read_raw_data(const std::string &file_path, file_reader::buffer<unsi
std::println("Uncompress failed {}", r);
throw std::runtime_error("Uncompress fail");
}
return true;
}
@ -126,11 +135,15 @@ static void apply_palette(file_reader::buffer<unsigned char> &data, file_reader:
}
}
lily_png::metadata lily_png::read_png(const std::string &file_path, file_reader::buffer<unsigned char> &data)
std::expected<lily_png::metadata, lily_png::png_error> lily_png::read_png(const std::string &file_path, file_reader::buffer<unsigned char> &data)
{
file_reader::buffer<unsigned char> tmp_data{};
metadata meta{0};
read_raw_data(file_path, tmp_data, meta);
auto ret = read_raw_data(file_path, tmp_data, meta);
if (!ret)
{
return std::unexpected(ret.error());
}
if (palette_found == true)
{
file_reader::buffer<unsigned char> dest_palette{};

9
src/lily_png.h
View file

@ -16,6 +16,13 @@ namespace lily_png
unsigned char b = 0;
};
enum class png_error
{
file_doesnt_exist,
read_failed,
file_is_not_a_png
};
metadata read_png(const std::string &file_path, file_reader::buffer<unsigned char> &data);
std::expected<metadata, png_error> read_png(const std::string &file_path, file_reader::buffer<unsigned char> &data);
}

4
src/utils.cpp
View file

@ -4,6 +4,7 @@
size_t lily_png::get_pixel_bit_size(const metadata &meta)
{
size_t ret = 0;
std::println("Bit depth {} color {}", (int)meta.bit_depth, (int)meta.color_type);
switch (meta.color_type)
{
case static_cast<int>(color::grayscale):
@ -52,8 +53,9 @@ size_t lily_png::get_pixel_bit_size(const metadata &meta)
return ret;
}
size_t lily_png::get_uncompressed_size(const metadata meta)
size_t lily_png::get_uncompressed_size(const metadata &meta)
{
std::println("metadata{{ width: {}, height: {}, bit_depth: {}, color_type: {}, compression: {}, filter: {}, interface: {} }}", meta.width, meta.height, (int)meta.bit_depth, (int)meta.color_type, (int)meta.compression, (int)meta.filter, (int)meta.interface);
size_t ret = (meta.width * get_pixel_bit_size(meta) + 7)/8; //ceil() but for bytes
ret = (ret + 1) * meta.height;
std::println("Uncompressed size {}", ret);

2
src/utils.h
View file

@ -4,6 +4,6 @@
namespace lily_png
{
size_t get_pixel_bit_size(const metadata &meta);
size_t get_uncompressed_size(const metadata meta);
size_t get_uncompressed_size(const metadata &meta);
int paeth_predict(const int a, const int b, const int c);
}