More work on writing ZIPs

2 files changed, 130 insertions, 14 deletions

diff --git a/src/bar.txt b/src/bar.txt
new file mode 100644
index 0000000..adabbec
--- /dev/null
+++ b/src/bar.txt
@@ -0,0 +1 @@
+hello there 
\ No newline at end of file
diff --git a/src/main.zig b/src/main.zig
index cfcac3e..0d33600 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -58,7 +58,7 @@ allocator: std.mem.Allocator,
 end_of_central_directory_record: EndOfCentralDirectoryRecord,
 central_directory_headers: std.ArrayList(CentralDirectoryHeader),
 
-pub fn empty(allocator: std.mem.Allocator) !@This() {
+pub fn empty(allocator: std.mem.Allocator) @This() {
     return .{
         .allocator = allocator,
         .end_of_central_directory_record = EndOfCentralDirectoryRecord.empty(),
@@ -117,7 +117,6 @@ pub fn deinit(self: *@This()) void {
     self.central_directory_headers.deinit();
 }
 
-
 /// returns how much to seekBy after the signature  is found (becuase we'll now have read past it.)
 fn read_to_sig(reader: anytype, sig: u32) !i32 {
     const needle = @byteSwap(sig);
@@ -172,6 +171,25 @@ fn pump(reader: anytype, writer: anytype, expected_size_written: usize, expected
     if (crc32.final() != expected_crc32) return error.WrongChecksum;
 }
 
+fn pump_returning(reader: anytype, writer: anytype) !struct { written: usize, crc32: u32 } {
+    var buf = [_]u8{0} ** 1024;
+    var crc32 = std.hash.Crc32.init();
+    var written: usize = 0;
+    while (true) {
+        const read = try reader.read(&buf);
+        if (read == 0) break;
+        const write = buf[0..read];
+        try writer.writeAll(write);
+
+        crc32.update(write);
+        written += read;
+    }
+    return .{
+        .written = written,
+        .crc32 = crc32.final(),
+    };
+}
+
 const CentralDirectoryHeader = struct {
     const SIG: u32 = @as(u32, 0x02014b50);
     version_made_by: u16,
@@ -206,7 +224,7 @@ const CentralDirectoryHeader = struct {
         // TODO generics
         self.file_name_length = @intCast(self.file_name.len);
         self.extra_field_length = @intCast(self.extra_field.len);
-        self.file_comment_length  = @intCast(self.file_comment);
+        self.file_comment_length = @intCast(self.file_comment);
 
         try writer.writeIntLittle(u32, SIG);
         try writer.writeIntLittle(u16, self.version_made_by);
@@ -230,6 +248,30 @@ const CentralDirectoryHeader = struct {
         try writer.writeAll(self.file_comment);
     }
 
+    fn from(allocator: std.mem.Allocator, lfh: LocalFileHeader, offset: u32) !CentralDirectoryHeader {
+        // TODO generics
+        return .{
+            .version_needed_to_extract = lfh.version_needed_to_extract,
+            .general_purpose_bit_flag = lfh.general_purpose_bit_flag,
+            .compression_method = lfh.compression_method,
+            .last_mod_file_time = lfh.last_mod_file_time,
+            .last_mod_file_date = lfh.last_mod_file_date,
+            .crc32 = lfh.crc32,
+            .compressed_size = lfh.compressed_size,
+            .uncompressed_size = lfh.uncompressed_size,
+            .file_name_length = lfh.file_name_length,
+            .extra_field_length = lfh.extra_field_length,
+            .file_comment_length = 0,
+            .disk_number_start = 0,
+            .internal_file_attributes = 0,
+            .external_file_attributes = 0,
+            .relative_offset_of_local_header = offset,
+            .file_name = try allocator.dupe(lfh.file_name),
+            .extra_field = try allocator.dupe(lfh.extra_field),
+            .file_comment = [_]u8{},
+        };
+    }
+
     fn deinit(self: *CentralDirectoryHeader, allocator: std.mem.Allocator) void {
         allocator.free(self.file_name);
         allocator.free(self.extra_field);
@@ -254,7 +296,7 @@ const EndOfCentralDirectoryRecord = struct {
         });
     }
 
-    fn empty() !EndOfCentralDirectoryRecord {
+    fn empty() EndOfCentralDirectoryRecord {
         return .{
             .disk_number_this = 0,
             .disk_number_central_dir_start = 0,
@@ -307,6 +349,31 @@ const LocalFileHeader = struct {
         });
     }
 
+    fn from(allocator: std.mem.Allocator, path: []const u8) !LocalFileHeader {
+        const file = try std.fs.cwd().openFile(path, .{});
+        defer file.close();
+        const md = try file.metadata();
+        var rdr = file.reader();
+        var cw = std.io.countingWriter(std.io.null_writer);
+        var comp = try std.compress.deflate.compressor(allocator, cw, .{});
+        defer comp.deinit();
+        const written, const crc32 = try pump_returning(rdr, comp.writer());
+        return .{
+            .version_needed_to_extract = 1,
+            .general_purpose_bit_flag = std.bit_set.IntegerBitSet(16).initEmpty(),
+            .compression_method = .deflate,
+            .last_mod_file_time = 0, // TODO
+            .last_mod_file_date = 0, // TODO
+            .crc32 = crc32,
+            .compressed_size = @intCast(written),
+            .uncompressed_size = @intCast(md.size()), // TODO zip64 support
+            .file_name_length = path.len,
+            .extra_field_length = 0,
+            .file_name = allocator.dupe(u8, path),
+            .extra_field = &[_]u8{},
+        };
+    }
+
     fn write(self: *LocalFileHeader, writer: anytype) !void {
         self.file_name_length = @intCast(self.file_name.len);
         self.extra_field_length = @intCast(self.extra_field.len);
@@ -436,15 +503,15 @@ pub const Options = struct {
     allocator: std.mem.Allocator,
 };
 
-/// tar.zig compatibility, ish. It does a forwards only pass of a zipfile 
+/// tar.zig compatibility, ish. It does a forwards only pass of a zipfile
 pub fn pipeToFileSystem(dir: std.fs.Dir, reader: anytype, options: Options) !void {
     const allocator = options.allocator;
     // var peek_stream = std.io.peekStream(4, reader);
     // var peek_reader = peek_stream.reader();
-    var i: u32  = 0;
+    var i: u32 = 0;
     while (true) {
         std.log.err("reading file {}", .{i});
-        var lfh = LocalFileHeader.read(allocator, reader) catch |e|  switch (e) {
+        var lfh = LocalFileHeader.read(allocator, reader) catch |e| switch (e) {
             error.InvalidSignature => return, // done
             else => return e,
         };
@@ -459,17 +526,66 @@ pub fn pipeToFileSystem(dir: std.fs.Dir, reader: anytype, options: Options) !voi
             try lfh.extract(allocator, reader, writer);
         }
         // TODO skip data descriptor
-        i+=1;
+        i += 1;
     }
 }
 
 pub const WriteOptions = struct {};
 
-/// Write a whole zip file. file_iterator 
-pub fn write_zip(file_iterator: anytype, writer: anytype) !void {
-    _ = writer;
-    _ = file_iterator;
-    
+/// Write a whole zip file
+pub fn write_zip(allocator: std.mem.Allocator, path_iterator: anytype, writer: anytype) !void {
+    var cw = std.io.countingWriter(writer);
+    var zf = @This().empty(allocator);
+    defer zf.deinit();
+    while (path_iterator.next()) |path| {
+        const file = try std.fs.cwd().openFile(path, .{});
+        defer file.close();
+        var lfh = try LocalFileHeader.from(allocator, path);
+        defer lfh.deinit(allocator);
+        var cdh = try CentralDirectoryHeader.from(allocator, lfh, cw.bytes_written);
+        try zf.central_directory_headers.append(cdh);
+        try lfh.write(cw);
+        _ = pump_returning(file.reader(), cw);
+    }
+    const central_dir_offset = cw.bytes_written;
+    for (zf.central_directory_headers.items) |cdh| {
+        try cdh.write(cw);
+    }
+    const size_of_central_dir = cw.bytes_written - central_dir_offset;
+    var eocdr = EndOfCentralDirectoryRecord{
+        .disk_number_this = 0,
+        .disk_number_central_dir_start = 0,
+        .total_central_dir_entries_on_this_disk = zf.central_directory_headers.items.len,
+        .total_central_dir_entries = zf.central_directory_headers.items.len,
+        .size_of_central_dir = size_of_central_dir,
+        .central_dir_offset = central_dir_offset,
+        .comment_length = 0,
+        .comment = &[_]u8{},
+    };
+    try eocdr.write(cw);
+}
+
+const TestFileIter = struct {
+    files: [2][]const u8,
+    ix: usize,
+    fn next(self: TestFileIter) ?[]const u8 {
+        if (self.ix < 2) {
+            defer self.ix += 1;
+            return self.files[self.ix];
+        }
+        return null;
+    }
+};
+
+test "write" {
+    const allocator = std.testing.allocator;
+    const out = try std.fs.cwd().createFile("test_out.zip", .{});
+    defer out.close();
+    const tfi = TestFileIter{
+        .ix = 0,
+        .files = [_][]const u8{ "src/foo.txt", "src/bar.txt" },
+    };
+    try write_zip(allocator, tfi, out.writer());
 }
 
 test "open stream" {
@@ -526,7 +642,6 @@ test "subdir" {
     defer zf.deinit();
     try std.testing.expectEqual(true, zf.is_dir(0));
     try std.testing.expectEqual(false, zf.is_dir(1));
-    
 }
 test "pipe to filesystem" {
     var f = try std.fs.cwd().openFile("src/subfolder.zip", .{});