Iterator

pub const Iterator = struct

File

Code

pub const Iterator = struct {
    input: *File.Reader,

    cd_record_count: u64,
    cd_zip_offset: u64,
    cd_size: u64,

    cd_record_index: u64 = 0,
    cd_record_offset: u64 = 0,

    pub fn init(input: *File.Reader) !Iterator {
        const end_record = try EndRecord.findFile(input);

        if (!isMaxInt(end_record.record_count_disk) and end_record.record_count_disk > end_record.record_count_total)
            return error.ZipDiskRecordCountTooLarge;

        if (end_record.disk_number != 0 or end_record.central_directory_disk_number != 0)
            return error.ZipMultiDiskUnsupported;

        {
            const counts_valid = !isMaxInt(end_record.record_count_disk) and !isMaxInt(end_record.record_count_total);
            if (counts_valid and end_record.record_count_disk != end_record.record_count_total)
                return error.ZipMultiDiskUnsupported;
        }

        var result: Iterator = .{
            .input = input,
            .cd_record_count = end_record.record_count_total,
            .cd_zip_offset = end_record.central_directory_offset,
            .cd_size = end_record.central_directory_size,
        };
        if (!end_record.need_zip64()) return result;

        const locator_end_offset: u64 = @as(u64, end_record.comment_len) + @sizeOf(EndRecord) + @sizeOf(EndLocator64);
        const stream_len = try input.getSize();

        if (locator_end_offset > stream_len)
            return error.ZipTruncated;
        try input.seekTo(stream_len - locator_end_offset);
        const locator = input.interface.takeStruct(EndLocator64, .little) catch |err| switch (err) {
            error.ReadFailed => return input.err.?,
            error.EndOfStream => |e| return e,
        };
        if (!std.mem.eql(u8, &locator.signature, &end_locator64_sig))
            return error.ZipBadLocatorSig;
        if (locator.zip64_disk_count != 0)
            return error.ZipUnsupportedZip64DiskCount;
        if (locator.total_disk_count != 1)
            return error.ZipMultiDiskUnsupported;

        try input.seekTo(locator.record_file_offset);

        const record64 = input.interface.takeStruct(EndRecord64, .little) catch |err| switch (err) {
            error.ReadFailed => return input.err.?,
            error.EndOfStream => |e| return e,
        };

        if (!std.mem.eql(u8, &record64.signature, &end_record64_sig))
            return error.ZipBadEndRecord64Sig;

        if (record64.end_record_size < @sizeOf(EndRecord64) - 12)
            return error.ZipEndRecord64SizeTooSmall;
        if (record64.end_record_size > @sizeOf(EndRecord64) - 12)
            return error.ZipEndRecord64UnhandledExtraData;

        if (record64.version_needed_to_extract > 45)
            return error.ZipUnsupportedVersion;

        {
            const is_multidisk = record64.disk_number != 0 or
                record64.central_directory_disk_number != 0 or
                record64.record_count_disk != record64.record_count_total;
            if (is_multidisk)
                return error.ZipMultiDiskUnsupported;
        }

        if (isMaxInt(end_record.record_count_total)) {
            result.cd_record_count = record64.record_count_total;
        } else if (end_record.record_count_total != record64.record_count_total)
            return error.Zip64RecordCountTotalMismatch;

        if (isMaxInt(end_record.central_directory_offset)) {
            result.cd_zip_offset = record64.central_directory_offset;
        } else if (end_record.central_directory_offset != record64.central_directory_offset)
            return error.Zip64CentralDirectoryOffsetMismatch;

        if (isMaxInt(end_record.central_directory_size)) {
            result.cd_size = record64.central_directory_size;
        } else if (end_record.central_directory_size != record64.central_directory_size)
            return error.Zip64CentralDirectorySizeMismatch;

        return result;
    }

    pub fn next(self: *Iterator) !?Entry {
        if (self.cd_record_index == self.cd_record_count) {
            if (self.cd_record_offset != self.cd_size)
                return if (self.cd_size > self.cd_record_offset)
                    error.ZipCdOversized
                else
                    error.ZipCdUndersized;

            return null;
        }

        const header_zip_offset = self.cd_zip_offset + self.cd_record_offset;
        const input = self.input;
        try input.seekTo(header_zip_offset);
        const header = input.interface.takeStruct(CentralDirectoryFileHeader, .little) catch |err| switch (err) {
            error.ReadFailed => return input.err.?,
            error.EndOfStream => |e| return e,
        };
        if (!std.mem.eql(u8, &header.signature, &central_file_header_sig))
            return error.ZipBadCdOffset;

        self.cd_record_index += 1;
        self.cd_record_offset += @sizeOf(CentralDirectoryFileHeader) + header.filename_len + header.extra_len + header.comment_len;

        // Note: checking the version_needed_to_extract doesn't seem to be helpful, i.e. the zip file
        // at https://github.com/ninja-build/ninja/releases/download/v1.12.0/ninja-linux.zip
        // has an undocumented version 788 but extracts just fine.

        if (header.flags.encrypted)
            return error.ZipEncryptionUnsupported;
        // TODO: check/verify more flags
        if (header.disk_number != 0)
            return error.ZipMultiDiskUnsupported;

        var extents: FileExtents = .{
            .uncompressed_size = header.uncompressed_size,
            .compressed_size = header.compressed_size,
            .local_file_header_offset = header.local_file_header_offset,
        };

        if (header.extra_len > 0) {
            var extra_buf: [std.math.maxInt(u16)]u8 = undefined;
            const extra = extra_buf[0..header.extra_len];

            try input.seekTo(header_zip_offset + @sizeOf(CentralDirectoryFileHeader) + header.filename_len);
            input.interface.readSliceAll(extra) catch |err| switch (err) {
                error.ReadFailed => return input.err.?,
                error.EndOfStream => |e| return e,
            };

            var extra_offset: usize = 0;
            while (extra_offset + 4 <= extra.len) {
                const header_id = std.mem.readInt(u16, extra[extra_offset..][0..2], .little);
                const data_size = std.mem.readInt(u16, extra[extra_offset..][2..4], .little);
                const end = extra_offset + 4 + data_size;
                if (end > extra.len)
                    return error.ZipBadExtraFieldSize;
                const data = extra[extra_offset + 4 .. end];
                switch (@as(ExtraHeader, @fromBackingInt(@intCast(header_id)))) {
                    .zip64_info => try readZip64FileExtents(CentralDirectoryFileHeader, header, &extents, data),
                    else => {}, // ignore
                }
                extra_offset = end;
            }
        }

        return .{
            .version_needed_to_extract = header.version_needed_to_extract,
            .flags = header.flags,
            .compression_method = header.compression_method,
            .last_modification_time = header.last_modification_time,
            .last_modification_date = header.last_modification_date,
            .header_zip_offset = header_zip_offset,
            .crc32 = header.crc32,
            .filename_len = header.filename_len,
            .compressed_size = extents.compressed_size,
            .uncompressed_size = extents.uncompressed_size,
            .file_offset = extents.local_file_header_offset,
        };
    }

    pub const Entry = struct {
        version_needed_to_extract: u16,
        flags: GeneralPurposeFlags,
        compression_method: CompressionMethod,
        last_modification_time: u16,
        last_modification_date: u16,
        header_zip_offset: u64,
        crc32: u32,
        filename_len: u32,
        compressed_size: u64,
        uncompressed_size: u64,
        file_offset: u64,

        pub fn getFilename(self: Entry, stream: *File.Reader, filename_buf: []u8, options: ExtractOptions) ![]u8 {
            if (filename_buf.len < self.filename_len)
                return error.ZipInsufficientBuffer;
            switch (self.compression_method) {
                .store, .deflate => {},
                else => return error.UnsupportedCompressionMethod,
            }
            const filename = filename_buf[0..self.filename_len];
            {
                try stream.seekTo(self.header_zip_offset + @sizeOf(CentralDirectoryFileHeader));
                try stream.interface.readSliceAll(filename);
            }

            if (options.allow_backslashes) {
                std.mem.replaceScalar(u8, filename, '\\', '/');
            } else {
                if (std.mem.findScalar(u8, filename, '\\')) |_|
                    return error.ZipFilenameHasBackslash;
            }

            if (isBadFilename(filename))
                return error.ZipBadFilename;

            return filename;
        }

        pub fn extractTo(self: Entry, stream: *File.Reader, w: *Writer) !void {
            switch (self.compression_method) {
                .store, .deflate => {},
                else => return error.UnsupportedCompressionMethod,
            }

            const local_data_header_offset: u64 = local_data_header_offset: {
                const local_header = blk: {
                    try stream.seekTo(self.file_offset);
                    break :blk try stream.interface.takeStruct(LocalFileHeader, .little);
                };
                if (!std.mem.eql(u8, &local_header.signature, &local_file_header_sig))
                    return error.ZipBadFileOffset;
                if (local_header.version_needed_to_extract != self.version_needed_to_extract)
                    return error.ZipMismatchVersionNeeded;
                if (local_header.last_modification_time != self.last_modification_time)
                    return error.ZipMismatchModTime;
                if (local_header.last_modification_date != self.last_modification_date)
                    return error.ZipMismatchModDate;

                if (@as(u16, @bitCast(local_header.flags)) != @as(u16, @bitCast(self.flags)))
                    return error.ZipMismatchFlags;
                if (local_header.crc32 != 0 and local_header.crc32 != self.crc32)
                    return error.ZipMismatchCrc32;
                var extents: FileExtents = .{
                    .uncompressed_size = local_header.uncompressed_size,
                    .compressed_size = local_header.compressed_size,
                    .local_file_header_offset = 0,
                };
                if (local_header.extra_len > 0) {
                    var extra_buf: [std.math.maxInt(u16)]u8 = undefined;
                    const extra = extra_buf[0..local_header.extra_len];

                    {
                        try stream.seekTo(self.file_offset + @sizeOf(LocalFileHeader) + local_header.filename_len);
                        try stream.interface.readSliceAll(extra);
                    }

                    var extra_offset: usize = 0;
                    while (extra_offset + 4 <= local_header.extra_len) {
                        const header_id = std.mem.readInt(u16, extra[extra_offset..][0..2], .little);
                        const data_size = std.mem.readInt(u16, extra[extra_offset..][2..4], .little);
                        const end = extra_offset + 4 + data_size;
                        if (end > local_header.extra_len)
                            return error.ZipBadExtraFieldSize;
                        const data = extra[extra_offset + 4 .. end];
                        switch (@as(ExtraHeader, @fromBackingInt(@intCast(header_id)))) {
                            .zip64_info => try readZip64FileExtents(LocalFileHeader, local_header, &extents, data),
                            else => {}, // ignore
                        }
                        extra_offset = end;
                    }
                }

                if (extents.compressed_size != 0 and
                    extents.compressed_size != self.compressed_size)
                    return error.ZipMismatchCompLen;
                if (extents.uncompressed_size != 0 and
                    extents.uncompressed_size != self.uncompressed_size)
                    return error.ZipMismatchUncompLen;

                if (local_header.filename_len != self.filename_len)
                    return error.ZipMismatchFilenameLen;

                break :local_data_header_offset @as(u64, local_header.filename_len) +
                    @as(u64, local_header.extra_len);
            };

            const local_data_file_offset: u64 =
                @as(u64, self.file_offset) +
                @as(u64, @sizeOf(LocalFileHeader)) +
                local_data_header_offset;
            try stream.seekTo(local_data_file_offset);

            // TODO limit based on self.compressed_size

            switch (self.compression_method) {
                .store => {
                    stream.interface.streamExact64(w, self.uncompressed_size) catch |err| switch (err) {
                        error.ReadFailed => |e| return stream.err orelse e,
                        error.WriteFailed => |e| return e,
                        error.EndOfStream => return error.ZipDecompressTruncated,
                    };
                },
                .deflate => {
                    var flate_buffer: [flate.max_window_len]u8 = undefined;
                    var decompress: flate.Decompress = .init(&stream.interface, .raw, &flate_buffer);
                    decompress.reader.streamExact64(w, self.uncompressed_size) catch |err| switch (err) {
                        error.ReadFailed => |e| return decompress.err orelse (stream.err orelse e),
                        error.WriteFailed => |e| return e,
                        error.EndOfStream => return error.ZipDecompressTruncated,
                    };
                },
                else => return error.UnsupportedCompressionMethod,
            }
        }

        pub fn extract(
            self: Entry,
            stream: *File.Reader,
            options: ExtractOptions,
            filename_buf: []u8,
            dest: Io.Dir,
        ) !void {
            const io = stream.io;

            const filename = try self.getFilename(stream, filename_buf, options);

            // All entries that end in '/' are directories
            if (filename[filename.len - 1] == '/') {
                if (self.uncompressed_size != 0)
                    return error.ZipBadDirectorySize;
                try dest.createDirPath(io, filename[0 .. filename.len - 1]);
                return;
            }

            const out_file = blk: {
                if (std.fs.path.dirname(filename)) |dirname| {
                    var parent_dir = try dest.createDirPathOpen(io, dirname, .{});
                    defer parent_dir.close(io);

                    const basename = std.fs.path.basename(filename);
                    break :blk try parent_dir.createFile(io, basename, .{ .exclusive = true });
                }
                break :blk try dest.createFile(io, filename, .{ .exclusive = true });
            };
            defer out_file.close(io);
            var out_file_buffer: [1024]u8 = undefined;
            var file_writer = out_file.writer(io, &out_file_buffer);
            self.extractTo(stream, &file_writer.interface) catch |err| switch (err) {
                error.WriteFailed => |e| return file_writer.err orelse e,
                else => return err,
            };
            try file_writer.end();
        }
    };
}