Commit 270a5039d4

@@ -528,17 +528,39 @@ pub const IO_Uring = struct {
         return sqe;
     }
 
+    /// Used to select how the recv call should be handled.
+    pub const RecvBuffer = union(enum) {
+        /// io_uring will recv directly into this buffer
+        buffer: []u8,
+
+        /// io_uring will select a buffer that has previously been provided with `provide_buffers`.
+        /// The buffer group referenced by `group_id` must contain at least one buffer for the recv call to work.
+        /// `len` controls the number of bytes to read into the selected buffer.
+        buffer_selection: struct {
+            group_id: u16,
+            len: usize,
+        },
+    };
+
     /// Queues (but does not submit) an SQE to perform a `recv(2)`.
     /// Returns a pointer to the SQE.
     pub fn recv(
         self: *IO_Uring,
         user_data: u64,
         fd: os.fd_t,
-        buffer: []u8,
+        buffer: RecvBuffer,
         flags: u32,
     ) !*io_uring_sqe {
         const sqe = try self.get_sqe();
-        io_uring_prep_recv(sqe, fd, buffer, flags);
+        switch (buffer) {
+            .buffer => |slice| io_uring_prep_recv(sqe, fd, slice, flags),
+            .buffer_selection => |selection| {
+                io_uring_prep_rw(.RECV, sqe, fd, 0, selection.len, 0);
+                sqe.rw_flags = flags;
+                sqe.flags |= linux.IOSQE_BUFFER_SELECT;
+                sqe.buf_index = selection.group_id;
+            },
+        }
         sqe.user_data = user_data;
         return sqe;
     }
@@ -2014,7 +2036,7 @@ test "accept/connect/send/recv" {
 
     const send = try ring.send(0xeeeeeeee, client, buffer_send[0..], 0);
     send.flags |= linux.IOSQE_IO_LINK;
-    _ = try ring.recv(0xffffffff, cqe_accept.res, buffer_recv[0..], 0);
+    _ = try ring.recv(0xffffffff, cqe_accept.res, .{ .buffer = buffer_recv[0..] }, 0);
     try testing.expectEqual(@as(u32, 2), try ring.submit());
 
     const cqe_send = try ring.copy_cqe();
@@ -2282,7 +2304,7 @@ test "accept/connect/recv/link_timeout" {
         .flags = 0,
     }, cqe_connect);
 
-    const sqe_recv = try ring.recv(0xffffffff, cqe_accept.res, buffer_recv[0..], 0);
+    const sqe_recv = try ring.recv(0xffffffff, cqe_accept.res, .{ .buffer = buffer_recv[0..] }, 0);
     sqe_recv.flags |= linux.IOSQE_IO_LINK;
 
     const ts = os.linux.kernel_timespec{ .tv_sec = 0, .tv_nsec = 1000000 };
@@ -2469,7 +2491,7 @@ test "accept/connect/recv/cancel" {
         .flags = 0,
     }, cqe_connect);
 
-    _ = try ring.recv(0xffffffff, cqe_accept.res, buffer_recv[0..], 0);
+    _ = try ring.recv(0xffffffff, cqe_accept.res, .{ .buffer = buffer_recv[0..] }, 0);
     try testing.expectEqual(@as(u32, 1), try ring.submit());
 
     const sqe_cancel = try ring.cancel(0x99999999, 0xffffffff, 0);