pwrite

Signed-off-by: Loris Cro <kappaloris@gmail.com>

lib/std/event/loop.zig

@@ -1020,9 +1020,43 @@ pub const Loop = struct {
         }
     }
 
+    /// Performs an async `os.pwrite` using a separate thread.
+    /// `fd` must block and not return EAGAIN.
+    pub fn pwrite(self: *Loop, fd: os.fd_t, bytes: []const u8, offset: u64, simulate_evented: bool) os.PWriteError!usize {
+        if (simulate_evented) {
+            var req_node = Request.Node{
+                .data = .{
+                    .msg = .{
+                        .pwrite = .{
+                            .fd = fd,
+                            .bytes = bytes,
+                            .offset = offset,
+                            .result = undefined,
+                        },
+                    },
+                    .finish = .{ .TickNode = .{ .data = @frame() } },
+                },
+            };
+            suspend {
+                self.posixFsRequest(&req_node);
+            }
+            return req_node.data.msg.pwrite.result;
+        } else {
+            while (true) {
+                return os.pwrite(fd, bytes, offset) catch |err| switch (err) {
+                    error.WouldBlock => {
+                        self.waitUntilFdWritable(fd);
+                        continue;
+                    },
+                    else => return err,
+                };
+            }
+        }
+    }
+
     /// Performs an async `os.pwritev` using a separate thread.
     /// `fd` must block and not return EAGAIN.
-    pub fn pwritev(self: *Loop, fd: os.fd_t, iov: []const os.iovec_const, offset: u64) os.WriteError!usize {
+    pub fn pwritev(self: *Loop, fd: os.fd_t, iov: []const os.iovec_const, offset: u64) os.PWriteError!usize {
         var req_node = Request.Node{
             .data = .{
                 .msg = .{
@@ -1194,6 +1228,9 @@ pub const Loop = struct {
                     .writev => |*msg| {
                         msg.result = os.writev(msg.fd, msg.iov);
                     },
+                    .pwrite => |*msg| {
+                        msg.result = os.pwrite(msg.fd, msg.bytes, msg.offset);
+                    },
                     .pwritev => |*msg| {
                         msg.result = os.pwritev(msg.fd, msg.iov, msg.offset);
                     },
@@ -1263,6 +1300,7 @@ pub const Loop = struct {
             readv: ReadV,
             write: Write,
             writev: WriteV,
+            pwrite: PWrite,
             pwritev: PWriteV,
             pread: PRead,
             preadv: PReadV,
@@ -1306,6 +1344,15 @@ pub const Loop = struct {
                 pub const Error = os.WriteError;
             };
 
+            pub const PWrite = struct {
+                fd: os.fd_t,
+                bytes: []const u8,
+                offset: usize,
+                result: Error!usize,
+
+                pub const Error = os.PWriteError;
+            };
+
             pub const PWriteV = struct {
                 fd: os.fd_t,
                 iov: []const os.iovec_const,

lib/std/fs/file.zig

@@ -566,10 +566,12 @@ pub const File = struct {
     pub fn pwrite(self: File, bytes: []const u8, offset: u64) PWriteError!usize {
         if (is_windows) {
             return windows.WriteFile(self.handle, bytes, offset, self.intended_io_mode);
-        } else if (self.capable_io_mode != self.intended_io_mode) {
-            return std.event.Loop.instance.?.pwrite(self.handle, bytes, offset);
-        } else {
+        }
+
+        if (self.intended_io_mode == .blocking) {
             return os.pwrite(self.handle, bytes, offset);
+        } else {
+            return std.event.Loop.instance.?.pwrite(self.handle, bytes, offset, self.capable_io_mode != self.intended_io_mode);
         }
     }
 

lib/std/os.zig

@@ -875,12 +875,7 @@ pub fn pwrite(fd: fd_t, bytes: []const u8, offset: u64) PWriteError!usize {
             EINTR => continue,
             EINVAL => unreachable,
             EFAULT => unreachable,
-            EAGAIN => if (std.event.Loop.instance) |loop| {
-                loop.waitUntilFdWritable(fd);
-                continue;
-            } else {
-                return error.WouldBlock;
-            },
+            EAGAIN => return error.WouldBlock,
             EBADF => return error.NotOpenForWriting, // Can be a race condition.
             EDESTADDRREQ => unreachable, // `connect` was never called.
             EDQUOT => return error.DiskQuota,