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Refine and fix bugs in the Oar library
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kayomn 2023-02-24 00:35:36 +00:00
parent 2a0f821e64
commit 78ae403f61
1 changed files with 191 additions and 146 deletions
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337
source/oar.cpp
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@ -3,14 +3,25 @@ export module oar;
import coral; import coral;
import coral.files; import coral.files;
constexpr coral::usize signature_length{4}; /**
* Length of the full magic signature at the beginning of an Oar file.
*/
constexpr coral::usize signature_length {4};
constexpr coral::usize signature_version_length{1}; /**
* Length of the magic signature at the beginning of an Oar file without the version indicator
* byte.
*/
constexpr coral::usize signature_identifier_length {signature_length - 1};
constexpr coral::usize signature_identifier_length{signature_length - signature_version_length}; /**
* Hardcoded signature magic value that this implementation of Oar expects when reading archives.
constexpr coral::u8 signature_magic[signature_length]{'o', 'a', 'r', 0}; */
constexpr coral::u8 signature_magic[signature_length] {'o', 'a', 'r', 0};
/**
* Oar file header format.
*/
struct header { struct header {
coral::u8 signature_magic[signature_length]; coral::u8 signature_magic[signature_length];
@ -21,6 +32,9 @@ struct header {
static_assert(sizeof(header) == 512); static_assert(sizeof(header) == 512);
/**
* Oar file header format.
*/
struct entry { struct entry {
coral::path path; coral::path path;
@ -33,144 +47,168 @@ struct entry {
static_assert(sizeof(entry) == 512); static_assert(sizeof(entry) == 512);
export namespace oar { /**
struct archive_file_reader : public coral::file_reader { * Archive file access interface.
enum class [[nodiscard]] close_result { */
ok, struct archive_file : public coral::file_reader {
}; /**
* Results of a find operation performed on an [archive_file].
enum class [[nodiscard]] open_result { *
ok, * [find_result::ok] means that the find operation was successful.
io_unavailable, *
archive_invalid, * [find_result::io_unavailable] signals a failure to communicate with the underlying
archive_unsupported, * [coral::file_reader] for whatever reason.
not_found, *
}; * [find_result::archive_invalid] signals that data was read but it does not match the format
* of an Oar archive. This is typically because the underlying [coral::file_reader] is not
archive_file_reader(coral::file_reader * archive_reader) { * reading from an Oar archive file.
this->archive_reader = archive_reader; *
this->data_offset = 0; * [find_result::archive_unsupported] signals that data was read and was formatted as expected
this->data_length = 0; * for an Oar archive, however, it is from an unsupported version of the archive format.
this->data_cursor = 0; *
} * [find_result::not_found] indicates that no entry in the archive could be found that matches
* the given query.
close_result close() { */
return close_result::ok; enum class [[nodiscard]] find_result {
} ok,
io_unavailable,
bool is_open() const { archive_invalid,
return this->data_offset >= sizeof(header); archive_unsupported,
} not_found,
open_result open(coral::path const & file_path) {
if (this->is_open()) switch (this->close()) {
case close_result::ok: break;
default: coral::unreachable();
}
if (!this->archive_reader->seek(0).is_ok()) return open_result::io_unavailable;
constexpr coral::usize header_size = sizeof(header);
coral::u8 archive_header_buffer[header_size]{0};
{
coral::expected const read_bytes{archive_reader->read(archive_header_buffer)};
if ((!read_bytes.is_ok()) || (read_bytes.value() != header_size))
return open_result::archive_invalid;
}
header const * const archive_header{reinterpret_cast<header const *>(archive_header_buffer)};
if (!coral::equals({archive_header->signature_magic, signature_identifier_length},
{signature_magic, signature_identifier_length})) return open_result::archive_invalid;
if (archive_header->signature_magic[signature_identifier_length] !=
signature_magic[signature_identifier_length]) return open_result::archive_unsupported;
// Read file table.
coral::u64 head{0};
coral::u64 tail{archive_header->entry_count - 1};
constexpr coral::usize entry_size{sizeof(entry)};
coral::u8 file_entry_buffer[entry_size]{0};
while (head <= tail) {
coral::u64 const midpoint{head + ((tail - head) / 2)};
if (!archive_reader->seek(header_size + (entry_size * midpoint)).is_ok())
return open_result::archive_invalid;
{
coral::expected const read_bytes{archive_reader->read(file_entry_buffer)};
if ((!read_bytes.is_ok()) || (read_bytes.value() != header_size))
return open_result::archive_invalid;
}
entry const * const archive_entry{reinterpret_cast<entry const *>(file_entry_buffer)};
coral::size const comparison{file_path.compare(archive_entry->path)};
if (comparison == 0) {
this->data_offset = archive_entry->data_offset;
this->data_length = archive_entry->data_length;
this->data_cursor = archive_entry->data_offset;
return open_result::ok;
}
if (comparison > 0) {
head = (midpoint + 1);
} else {
tail = (midpoint - 1);
}
}
return open_result::not_found;
}
coral::expected<coral::usize, coral::io_error> read(coral::slice<coral::u8> const & buffer) override {
if (!this->is_open()) return coral::io_error::unavailable;
if (this->archive_reader->seek(this->data_offset + this->data_cursor).is_ok())
return coral::io_error::unavailable;
coral::expected const bytes_read{this->archive_reader->read(buffer.sliced(0,
coral::min(buffer.length, static_cast<coral::usize>((
this->data_offset + this->data_length) - this->data_cursor))))};
if (!bytes_read.is_ok()) this->data_cursor += bytes_read.value();
return bytes_read;
}
coral::expected<coral::u64, coral::io_error> seek(coral::u64 offset) override {
if (!this->is_open()) return coral::io_error::unavailable;
return coral::io_error::unavailable;
}
coral::expected<coral::u64, coral::io_error> tell() override {
if (!this->is_open()) return coral::io_error::unavailable;
return this->data_cursor;
}
private:
coral::file_reader * archive_reader;
coral::u64 data_offset;
coral::u64 data_length;
coral::u64 data_cursor;
}; };
archive_file(coral::file_reader * archive_reader) {
this->archive_reader = archive_reader;
}
/**
* Performs a lookup for a file entry matching the path `file_path` in the archive, returning
* [find_result] to indicate the result of the operation.
*/
find_result find(coral::path const & file_path) {
this->data_offset = 0;
this->data_length = 0;
this->data_cursor = 0;
if (!this->archive_reader->seek(0).is_ok()) return find_result::io_unavailable;
constexpr coral::usize header_size {sizeof(header)};
coral::u8 archive_header_buffer[header_size] {0};
if (!this->archive_reader->read(archive_header_buffer).and_test(
[](coral::usize value) -> bool { return value == header_size; }))
return find_result::archive_invalid;
header const * const archive_header {
reinterpret_cast<header const *>(archive_header_buffer)};
if (!coral::equals({archive_header->signature_magic, signature_identifier_length},
{signature_magic, signature_identifier_length})) return find_result::archive_invalid;
if (archive_header->signature_magic[signature_identifier_length] !=
signature_magic[signature_identifier_length]) return find_result::archive_unsupported;
// Read file table.
coral::u64 head {0};
coral::u64 tail {archive_header->entry_count - 1};
constexpr coral::usize entry_size {sizeof(entry)};
coral::u8 archive_entry_buffer[entry_size] {0};
while (head <= tail) {
coral::u64 const midpoint {head + ((tail - head) / 2)};
if (!this->archive_reader->seek(header_size + (entry_size * midpoint)).is_ok())
return find_result::archive_invalid;
if (!this->archive_reader->read(archive_entry_buffer).and_test(
[](coral::usize value) -> bool { return value == entry_size; }))
return find_result::archive_invalid;
entry const * const archive_entry {
reinterpret_cast<entry const *>(archive_entry_buffer)};
coral::size const comparison {file_path.compare(archive_entry->path)};
if (comparison == 0) {
this->data_offset = archive_entry->data_offset;
this->data_length = archive_entry->data_length;
this->data_cursor = archive_entry->data_offset;
return find_result::ok;
}
if (comparison > 0) {
head = (midpoint + 1);
} else {
tail = (midpoint - 1);
}
}
return find_result::not_found;
}
/**
* Attempts to read `data.length` bytes from the file and fill `data` with it, returning the
* number of bytes actually read or a [coral::io_error] value to indicate an error occured.
*/
coral::expected<coral::usize, coral::io_error> read(coral::slice<coral::u8> const & data) override {
if (this->data_offset < sizeof(header)) return coral::io_error::unavailable;
coral::usize const data_tail {this->data_offset + this->data_length};
if (!this->archive_reader->seek(coral::clamp(this->data_offset + this->data_cursor,
this->data_offset, data_tail)).is_ok()) return coral::io_error::unavailable;
coral::expected const data_read {this->archive_reader->read(
data.sliced(0, coral::min(data.length, data_tail - this->data_cursor)))};
if (data_read.is_ok()) this->data_cursor += data_read.value();
return data_read;
}
/**
* Attempts to seek to `offset` absolute position in the file, returning the new absolute
* cursor or a [coral::io_error] value to indicate an error occured.
*/
coral::expected<coral::u64, coral::io_error> seek(coral::u64 offset) override {
if (this->data_offset < sizeof(header)) return coral::io_error::unavailable;
this->data_cursor = offset;
return coral::io_error::unavailable;
}
/**
* Attempts to read to read the absolute file cursor position, returning it or a
* [coral::io_error] value to indicate an error occured.
*/
coral::expected<coral::u64, coral::io_error> tell() override {
if (this->data_offset < sizeof(header)) return coral::io_error::unavailable;
return this->data_cursor;
}
private:
coral::file_reader * archive_reader {nullptr};
coral::u64 data_offset {0};
coral::u64 data_length {0};
coral::u64 data_cursor {0};
};
export namespace oar {
struct archive : public coral::fs { struct archive : public coral::fs {
archive(coral::fs * backing_fs, coral::path const & archive_path) { archive(coral::fs * backing_fs, coral::path const & archive_path) {
this->backing_fs = backing_fs; this->backing_fs = backing_fs;
this->archive_path = archive_path; this->archive_path = archive_path;
} }
/**
* Queries the archive for the [coral::fs::access_rules] and returns them.
*/
access_rules query_access() override { access_rules query_access() override {
return { return {
.can_read = true, .can_read = true,
@ -178,27 +216,34 @@ export namespace oar {
}; };
} }
/**
* Attempts to open a readable context for reading from the archive file identified by
* `file_path`, doing nothing if the requested file could not be found.
*/
void read_file(coral::path const & file_path, void read_file(coral::path const & file_path,
coral::closure<void(coral::file_reader &)> const & then) override { coral::closure<void(coral::file_reader &)> const & then) override {
if ((this->backing_fs == nullptr) || (this->archive_path.byte_size() == 0)) return; if ((this->backing_fs == nullptr) || (this->archive_path.byte_size() == 0)) return;
this->backing_fs->read_file(this->archive_path, [&](coral::file_reader & archive_reader) { this->backing_fs->read_file(this->archive_path,
archive_file_reader file_reader{&archive_reader}; [&](coral::file_reader & archive_reader) {
archive_file file{&archive_reader};
if (file_reader.open(file_path) != archive_file_reader::open_result::ok) return; if (file.find(file_path) != archive_file::find_result::ok) return;
then(file_reader); then(file);
});
if (file_reader.close() != archive_file_reader::close_result::ok) return; }
});
}
/**
* Attempts to open a writable context for reading from the archive file identified by
* `file_path`, however this will always do nothing as archive file-systems are read-only.
*/
void write_file(coral::path const & file_path, void write_file(coral::path const & file_path,
coral::closure<void(coral::file_writer &)> const & then) override { coral::closure<void(coral::file_writer &)> const & then) override {
// Read-only file system. // Read-only file system.
} }
private: private:
coral::fs * backing_fs; coral::fs * backing_fs;