From da6b404545803a9960845856448a4d666122a4ff Mon Sep 17 00:00:00 2001
From: Martin Ashby <martin@ashbysoft.com>
Date: Sat, 23 Sep 2023 22:50:34 +0100
Subject: Add query message

---
 src/main.zig  |  2 ++
 src/query.zig | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)
 create mode 100644 src/query.zig

diff --git a/src/main.zig b/src/main.zig
index e539f2f..86e1983 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -7,6 +7,7 @@ const ErrorResponse = @import("error_response.zig");
 const ReadyForQuery = @import("ready_for_query.zig");
 const ParameterStatus = @import("parameter_status.zig");
 const BackendKeyData = @import("backend_key_data.zig");
+const Query = @import("query.zig");
 const Conn = @import("conn.zig");
 
 pub const ProtocolError = error{
@@ -115,4 +116,5 @@ test {
     _ = ReadyForQuery;
     _ = ParameterStatus;
     _ = BackendKeyData;
+    _ = Query;
 }
diff --git a/src/query.zig b/src/query.zig
new file mode 100644
index 0000000..8f07b5f
--- /dev/null
+++ b/src/query.zig
@@ -0,0 +1,55 @@
+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;
+
+pub const Tag: u8 = 'Q';
+
+const Query = @This();
+
+string: []const u8,
+owned: bool = false,
+
+pub fn read(a: std.mem.Allocator, b: []const u8) !Query {
+    return .{
+        .string = try a.dupe(u8, b[0..(b.len-1)]), // Drop the null terminator
+        .owned = true,
+    };
+}
+
+pub fn write(self: Query, _: std.mem.Allocator, stream_writer: anytype) !void {
+    try stream_writer.writeByte(Tag);
+    try stream_writer.writeIntBig(u32, @as(u32, @intCast(self.string.len+5)));
+    try stream_writer.writeAll(self.string);
+    try stream_writer.writeByte(0);
+}
+
+pub fn deinit(self: *Query, a: std.mem.Allocator) void {
+    if (self.owned) a.free(self.string);
+}
+
+test "round trip" {
+    const allocator = std.testing.allocator;
+    var sm = Query{
+        .string = "Hello",
+    };
+    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 Query.read(allocator, buf);
+    defer sm2.deinit(allocator);
+    try std.testing.expectEqualStrings("Hello", sm2.string);
+}
-- 
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