Initial

2 files changed, 204 insertions, 0 deletions

diff --git a/src/hello.zip b/src/hello.zip
new file mode 100644
index 0000000..d17d176
--- /dev/null
+++ b/src/hello.zip
diff --git a/src/main.zig b/src/main.zig
new file mode 100644
index 0000000..d5345f0
--- /dev/null
+++ b/src/main.zig
@@ -0,0 +1,204 @@
+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])});
+}