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const std = @import("std");
const testing = std.testing;
// https://pkware.cachefly.net/webdocs/APPNOTE/APPNOTE-6.3.10.TXT
const ZipFile = struct {
// [local file header 1]
// [encryption header 1]
// [file data 1]
// [data descriptor 1]
// .
// .
// .
// [local file header n]
// [encryption header n]
// [file data n]
// [data descriptor n]
// [archive decryption header]
// [archive extra data record]
// [central directory header 1]
// .
// .
// .
// [central directory header n]
// [zip64 end of central directory record]
// [zip64 end of central directory locator]
// [end of central directory record]
};
const LocalFileHeader = packed struct {
const GPBF = packed struct(u16) {
encrypted: bool = false,
};
const SIG: u32 = 0x04034b50;
sig: u32 = SIG,
// version needed to extract 2 bytes
general_purpose_bit_flag: GPBF,
// compression method 2 bytes
// last mod file time 2 bytes
// last mod file date 2 bytes
// crc-32 4 bytes
// compressed size 4 bytes
// uncompressed size 4 bytes
// file name length 2 bytes
// extra field length 2 bytes
// file name (variable size)
// extra field (variable size)
};
const DataDescriptor = struct {
const SIG: u32 = 0x08074b50;
sig: u32 = SIG,
// crc-32 4 bytes
// compressed size 4 bytes
// uncompressed size 4 bytes
};
const ArchiveExtraDataRecord = struct {
const SIG: u32 = 0x08064b50;
sig: u32 = SIG,
// extra field length 4 bytes
// extra field data (variable size)
};
const CentralDirectoryHeader = packed struct {
const SIG: u32 = 0x02014b50;
// central file header signature 4 bytes ()
sig: u32 = SIG,
// version made by 2 bytes
version_made_by: u16,
// version needed to extract 2 bytes
version_needed_to_extract: u16,
// general purpose bit flag 2 bytes
general_purpose_bit_flag: u16,
// compression method 2 bytes
compression_method: u16,
// last mod file time 2 bytes
last_mod_file_time: u16,
// last mod file date 2 bytes
last_mod_file_date: u16,
// crc-32 4 bytes
crc32: u32,
// compressed size 4 bytes
compressed_size: u32,
// uncompressed size 4 bytes
uncompressed_size: u32,
// file name length 2 bytes
file_name_length: u16,
// extra field length 2 bytes
extra_field_length: u16,
// file comment length 2 bytes
file_comment_length: u16,
// disk number start 2 bytes
disk_number_start: u16,
// internal file attributes 2 bytes
internal_file_attributes: u16,
// external file attributes 4 bytes
external_file_attributes: u32,
// relative offset of local header 4 bytes
relative_offset_of_local_header: u16,
// file name (variable size)
// extra field (variable size)
// file comment (variable size)
};
const DigitalSignature = struct {
const SIG: u32 = 0x05054b50;
sig: u32 = SIG,
// size of data 2 bytes
// signature data (variable size)
};
const Zip64EndOfCentralDirectoryRecord = struct {
const SIG: u32 = 0x06064b50;
sig: u32 = SIG,
// size of zip64 end of central
// directory record 8 bytes
// version made by 2 bytes
// version needed to extract 2 bytes
// number of this disk 4 bytes
// number of the disk with the
// start of the central directory 4 bytes
// total number of entries in the
// central directory on this disk 8 bytes
// total number of entries in the
// central directory 8 bytes
// size of the central directory 8 bytes
// offset of start of central
// directory with respect to
// the starting disk number 8 bytes
// zip64 extensible data sector (variable size)
};
const Zip64EndOfCentralDirectoryLocator = struct {
const SIG: u32 = 0x07064b50;
sig: u32 = SIG,
// number of the disk with the
// start of the zip64 end of
// central directory 4 bytes
// relative offset of the zip64
// end of central directory record 8 bytes
// total number of disks 4 bytes
};
const EndOfCentralDirectoryRecord = packed struct {
const SIG: u32 = 0x06054b50;
// // end of central dir signa SIG: u32 = 0x06054b50;ure 4 bytes (0x06054b50)
sig: u32 = SIG, // 504b0506
// number of this disk 2 bytes
disk_number_this: u16, // 0000
// number of the disk with the
// start of the central directory 2 bytes
disk_number_central_dir_start: u16, // 0000
// total number of entries in the
// central directory on this disk 2 bytes
total_central_dir_entries_on_this_disk: u16, // 0100
// total number of entries in
// the central directory 2 bytes
total_central_dir_entries: u16, // 0100
// size of the central directory 4 bytes
size_of_central_dir: u32, // 4f000000
// offset of start of central
// directory with respect to
// the starting disk number 4 bytes
central_dir_offset: u32, // 4e000000
// .ZIP file comment length 2 bytes
comment_length: u16, // 0000
// .ZIP file comment (variable size)
// comment: [*]u8,
fn from(bytes: []const u8) !EndOfCentralDirectoryRecord {
var fbs = std.io.fixedBufferStream(bytes);
var rr = fbs.reader();
return EndOfCentralDirectoryRecord{
.sig = try rr.readIntLittle(u32),
.disk_number_this = try rr.readIntLittle(u16),
.disk_number_central_dir_start = try rr.readIntLittle(u16),
.total_central_dir_entries_on_this_disk = try rr.readIntLittle(u16),
.total_central_dir_entries = try rr.readIntLittle(u16),
.size_of_central_dir = try rr.readIntLittle(u32),
.central_dir_offset = try rr.readIntLittle(u32),
.comment_length = try rr.readIntLittle(u16),
// .comment = rr.read()
};
}
};
test "foo" {
const test_zip = @embedFile("hello.zip");
var fbs = std.io.fixedBufferStream(test_zip);
const eocdr_search_width_max: usize = 64_000;
var eocdr_search_buf: [eocdr_search_width_max]u8 = undefined;
const epos = try fbs.getEndPos();
const eocdr_search_width: usize = @min(epos, eocdr_search_width_max);
const eocdr_seek_start: usize = epos - eocdr_search_width;
std.log.err("epos {}", .{epos});
std.log.err("eocdr_search_width {}", .{eocdr_search_width});
std.log.err("eocdr_seek_start {}", .{eocdr_seek_start});
try fbs.seekTo(eocdr_seek_start);
const eocdr_did_read = try fbs.read(&eocdr_search_buf);
std.log.err("eocdr_did_read {}", .{eocdr_did_read});
const needle: [4]u8 = @bitCast(EndOfCentralDirectoryRecord.SIG);
const eocdr_start = std.mem.indexOf(u8, eocdr_search_buf[0..eocdr_search_width], &needle) orelse return error.NoEndOfCentralDirectoryRecord;
std.log.err("eocdr_start {}", .{eocdr_start});
try fbs.seekTo(eocdr_start);
const eocdr_pos = try fbs.getPos();
std.log.err("eocdr_pos {}", .{eocdr_pos});
// const eocdr = try fbs.reader().readStruct(EndOfCentralDirectoryRecord);
// _ = eocdr;
// _ = eocdr;
var rr = fbs.reader();
const eocdrb = try rr.readAllAlloc(std.testing.allocator, 10_000_000);
defer std.testing.allocator.free(eocdrb);
const eocdr = try EndOfCentralDirectoryRecord.from(eocdrb);
_ = eocdr;
// const comment = try rr.readAllAlloc(std.testing.allocator, eocdr.comment_length);
// defer std.testing.allocator.free(comment);
std.log.err("eocdrb {} len {}", .{ std.fmt.fmtSliceHexLower(eocdrb), eocdrb.len });
std.log.err("sz {}", .{@sizeOf(EndOfCentralDirectoryRecord)});
}
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