2 files changed, 85 insertions, 0 deletions

diff --git a/src/copy_in_response.zig b/src/copy_in_response.zig
new file mode 100644
index 0000000..f6ed84b
--- /dev/null
+++ b/src/copy_in_response.zig
@@ -0,0 +1,83 @@
+const std = @import("std");
+const log = std.log.scoped(.pgz);
+const ByteArrayList = std.ArrayList(u8);
+const ProtocolError = @import("main.zig").ProtocolError;
+const ClientError = @import("main.zig").ClientError;
+const enum_from_int = @import("main.zig").enum_from_int;
+const FormatCode = @import("main.zig").FormatCode;
+
+pub const Tag: u8 = 'G';
+// TODO generics  it's the same as CopyOutResponse and CopyBothResponse.
+const CopyInResponse = @This();
+
+overall_format_code: u8,
+format_codes: []const FormatCode, // owned
+
+pub fn read(a: std.mem.Allocator, b: []const u8) !CopyInResponse {
+    var fbs = std.io.fixedBufferStream(b);
+    var reader = fbs.reader();
+    const overall_format_code = try reader.readIntBig(u8);
+    const n_columns = try reader.readIntBig(u16);
+    var format_codes = try a.alloc(FormatCode, n_columns);
+    errdefer a.free(format_codes);
+    for (0..n_columns) |i| {
+        const int_format_code = try reader.readIntBig(u16);
+        format_codes[i] = enum_from_int(FormatCode, int_format_code) orelse return ProtocolError.InvalidFormatCode;
+    }
+    return .{
+        .overall_format_code = overall_format_code,
+        .format_codes = format_codes,
+    };
+}
+
+pub fn write(self: CopyInResponse, a: std.mem.Allocator, stream_writer: anytype) !void {
+    try stream_writer.writeIntBig(u8, Tag);
+    var al = ByteArrayList.init(a);
+    defer al.deinit();
+    var cw = std.io.countingWriter(al.writer());
+    var writer = cw.writer();
+    try writer.writeIntBig(u32, 0); // length placeholder
+    try writer.writeIntBig(u8, self.overall_format_code);
+    try writer.writeIntBig(u16, @intCast(self.format_codes.len));
+    for (self.format_codes) |format_code| {
+        try writer.writeIntBig(u16, @intFromEnum(format_code));
+    }
+    std.mem.writeIntBig(u32, al.items[0..4], @as(u32, @intCast(cw.bytes_written))); // Update length
+    try stream_writer.writeAll(al.items);
+}
+
+pub fn deinit(self: *CopyInResponse, a: std.mem.Allocator) void {
+    a.free(self.format_codes);
+}
+
+test "round trip" {
+    const allocator = std.testing.allocator;
+    var format_codes = try allocator.alloc(FormatCode, 3);
+    format_codes[0] = .Binary;
+    format_codes[1] = .Binary;
+    format_codes[2] = .Text;
+    var sm = CopyInResponse{
+        .overall_format_code = 1,
+        .format_codes = format_codes,
+    };
+    defer sm.deinit(allocator);
+
+    var bal = ByteArrayList.init(allocator);
+    defer bal.deinit();
+    try sm.write(allocator, bal.writer());
+
+    var fbs = std.io.fixedBufferStream(bal.items);
+    var reader = fbs.reader();
+    const tag = try reader.readByte();
+    try std.testing.expectEqual(Tag, tag);
+    const len = try reader.readIntBig(u32);
+    const buf = try allocator.alloc(u8, len - 4);
+    defer allocator.free(buf);
+    try reader.readNoEof(buf);
+    var sm2 = try CopyInResponse.read(allocator, buf);
+    defer sm2.deinit(allocator);
+
+    try std.testing.expectEqual(FormatCode.Binary, sm2.format_codes[0]);
+    try std.testing.expectEqual(FormatCode.Binary, sm2.format_codes[1]);
+    try std.testing.expectEqual(FormatCode.Text, sm2.format_codes[2]);
+}
diff --git a/src/main.zig b/src/main.zig
index 4186377..8bc4649 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -11,6 +11,7 @@ const Query = @import("query.zig");
 const DataRow = @import("data_row.zig");
 const RowDescription = @import("row_description.zig");
 const CommandComplete = @import("command_complete.zig");
+const CopyInResponse = @import("copy_in_response.zig");
 const Conn = @import("conn.zig");
 
 pub const ProtocolError = error{
@@ -129,4 +130,5 @@ test {
     _ = DataRow;
     _ = RowDescription;
     _ = CommandComplete;
+    _ = CopyInResponse;
 }