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const std = @import("std");
const testing = std.testing;
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 signature 4 bytes (0x06054b50)
sig: u32 = SIG,
// number of this disk 2 bytes
disk_number_this: u16,
// number of the disk with the
// start of the central directory 2 bytes
disk_number_central_dir_start: u16,
// total number of entries in the
// central directory on this disk 2 bytes
total_central_dir_entries_on_this_disk: u16,
// total number of entries in
// the central directory 2 bytes
total_central_dir_entries: u16,
// size of the central directory 4 bytes
size_of_central_dir: u32,
// offset of start of central
// directory with respect to
// the starting disk number 4 bytes
central_dir_offset: u32,
// .ZIP file comment length 2 bytes
comment_length: u16,
// .ZIP file comment (variable size)
// comment: [*]u8,
// fn comment_slice(self: EndOfCentralDirectoryRecord) []u8 {
// return self.comment[0..self.comment_length];
// }
};
test "foo" {
var mapped_mem: ?[]align(std.mem.page_size) u8 = null;
{
var file = try std.fs.cwd().openFile("src/hello.zip", .{});
errdefer file.close();
const file_len = std.math.cast(usize, try file.getEndPos()) orelse std.math.maxInt(usize);
mapped_mem = try std.os.mmap(
null,
file_len,
std.os.PROT.READ,
std.os.MAP.SHARED,
file.handle,
0,
);
file.close();
}
var mm = mapped_mem orelse return error.MMapFailed;
defer std.os.munmap(mm);
const cdr_search_start = if (mm.len < 64_000) 0 else mm.len - 64_000;
const needle: [4]u8 = @bitCast(CentralDirectoryHeader.SIG);
const eocdr_start = std.mem.indexOf(u8, mm[cdr_search_start..], &needle) orelse return error.EocdrNotFound;
const eocdr: *EndOfCentralDirectoryRecord = @ptrCast(@alignCast(mm[eocdr_start .. eocdr_start + @sizeOf(EndOfCentralDirectoryRecord)]));
std.log.err("needle: {} eocdr_start {} comment_length {}", .{ std.fmt.fmtSliceHexLower(&needle), eocdr_start, eocdr.comment_length });
const hh_p: *u32 = @ptrCast(mm[0..4].ptr);
const hh = hh_p.*;
try std.testing.expectEqual(LocalFileHeader.SIG, hh);
// std.log.err("mapped_mem len {} first 5 bytes {}", .{mm.len, std.fmt.fmtSliceHexUpper(mm[0..5])});
}
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