Commit 9d4eaf1e07

Andrew Kelley <superjoe30@gmail.com>
2018-09-30 23:23:42
update std lib API for I/O
std.io.FileInStream -> std.os.File.InStream std.io.FileInStream.init(file) -> file.inStream() std.io.FileOutStream -> std.os.File.OutStream std.io.FileOutStream.init(file) -> file.outStream() remove a lot of error code possibilities from os functions std.event.net.socketRead -> std.event.net.read std.event.net.socketWrite -> std.event.net.write add std.event.net.readv add std.event.net.writev add std.event.net.readvPosix add std.event.net.writevPosix add std.event.net.OutStream add std.event.net.InStream add std.event.io.InStream add std.event.io.OutStream
1 parent ba78ae0
doc/docgen.zig
@@ -41,12 +41,12 @@ pub fn main() !void {
     var out_file = try os.File.openWrite(out_file_name);
     defer out_file.close();
 
-    var file_in_stream = io.FileInStream.init(in_file);
+    var file_in_stream = in_file.inStream();
 
     const input_file_bytes = try file_in_stream.stream.readAllAlloc(allocator, max_doc_file_size);
 
-    var file_out_stream = io.FileOutStream.init(out_file);
-    var buffered_out_stream = io.BufferedOutStream(io.FileOutStream.Error).init(&file_out_stream.stream);
+    var file_out_stream = out_file.outStream();
+    var buffered_out_stream = io.BufferedOutStream(os.File.WriteError).init(&file_out_stream.stream);
 
     var tokenizer = Tokenizer.init(in_file_name, input_file_bytes);
     var toc = try genToc(allocator, &tokenizer);
example/guess_number/main.zig
@@ -6,8 +6,7 @@ const os = std.os;
 
 pub fn main() !void {
     var stdout_file = try io.getStdOut();
-    var stdout_file_stream = io.FileOutStream.init(stdout_file);
-    const stdout = &stdout_file_stream.stream;
+    const stdout = &stdout_file.outStream().stream;
 
     try stdout.print("Welcome to the Guess Number Game in Zig.\n");
 
src-self-hosted/errmsg.zig
@@ -278,7 +278,7 @@ pub const Msg = struct {
             Color.On => true,
             Color.Off => false,
         };
-        var stream = &std.io.FileOutStream.init(file).stream;
+        var stream = &file.outStream().stream;
         return msg.printToStream(stream, color_on);
     }
 };
src-self-hosted/libc_installation.zig
@@ -30,7 +30,7 @@ pub const LibCInstallation = struct {
         self: *LibCInstallation,
         allocator: *std.mem.Allocator,
         libc_file: []const u8,
-        stderr: *std.io.OutStream(std.io.FileOutStream.Error),
+        stderr: *std.io.OutStream(std.os.File.WriteError),
     ) !void {
         self.initEmpty();
 
@@ -100,7 +100,7 @@ pub const LibCInstallation = struct {
         }
     }
 
-    pub fn render(self: *const LibCInstallation, out: *std.io.OutStream(std.io.FileOutStream.Error)) !void {
+    pub fn render(self: *const LibCInstallation, out: *std.io.OutStream(std.os.File.WriteError)) !void {
         @setEvalBranchQuota(4000);
         try out.print(
             \\# The directory that contains `stdlib.h`.
src-self-hosted/main.zig
@@ -21,8 +21,8 @@ const errmsg = @import("errmsg.zig");
 const LibCInstallation = @import("libc_installation.zig").LibCInstallation;
 
 var stderr_file: os.File = undefined;
-var stderr: *io.OutStream(io.FileOutStream.Error) = undefined;
-var stdout: *io.OutStream(io.FileOutStream.Error) = undefined;
+var stderr: *io.OutStream(os.File.WriteError) = undefined;
+var stdout: *io.OutStream(os.File.WriteError) = undefined;
 
 const max_src_size = 2 * 1024 * 1024 * 1024; // 2 GiB
 
@@ -55,11 +55,11 @@ pub fn main() !void {
     const allocator = std.heap.c_allocator;
 
     var stdout_file = try std.io.getStdOut();
-    var stdout_out_stream = std.io.FileOutStream.init(stdout_file);
+    var stdout_out_stream = stdout_file.outStream();
     stdout = &stdout_out_stream.stream;
 
     stderr_file = try std.io.getStdErr();
-    var stderr_out_stream = std.io.FileOutStream.init(stderr_file);
+    var stderr_out_stream = stderr_file.outStream();
     stderr = &stderr_out_stream.stream;
 
     const args = try os.argsAlloc(allocator);
@@ -619,7 +619,7 @@ fn cmdFmt(allocator: *Allocator, args: []const []const u8) !void {
         }
 
         var stdin_file = try io.getStdIn();
-        var stdin = io.FileInStream.init(stdin_file);
+        var stdin = stdin_file.inStream();
 
         const source_code = try stdin.stream.readAllAlloc(allocator, max_src_size);
         defer allocator.free(source_code);
std/atomic/queue.zig
@@ -114,7 +114,7 @@ pub fn Queue(comptime T: type) type {
 
         fn dumpRecursive(optional_node: ?*Node, indent: usize) void {
             var stderr_file = std.io.getStdErr() catch return;
-            const stderr = &std.io.FileOutStream.init(stderr_file).stream;
+            const stderr = &stderr_file.outStream().stream;
             stderr.writeByteNTimes(' ', indent) catch return;
             if (optional_node) |node| {
                 std.debug.warn("0x{x}={}\n", @ptrToInt(node), node.data);
std/crypto/throughput_test.zig
@@ -130,7 +130,7 @@ fn printPad(stdout: var, s: []const u8) !void {
 
 pub fn main() !void {
     var stdout_file = try std.io.getStdOut();
-    var stdout_out_stream = std.io.FileOutStream.init(stdout_file);
+    var stdout_out_stream = stdout_file.outStream();
     const stdout = &stdout_out_stream.stream;
 
     var buffer: [1024]u8 = undefined;
std/debug/index.zig
@@ -34,10 +34,10 @@ const Module = struct {
 /// Tries to write to stderr, unbuffered, and ignores any error returned.
 /// Does not append a newline.
 var stderr_file: os.File = undefined;
-var stderr_file_out_stream: io.FileOutStream = undefined;
+var stderr_file_out_stream: os.File.OutStream = undefined;
 
 /// TODO multithreaded awareness
-var stderr_stream: ?*io.OutStream(io.FileOutStream.Error) = null;
+var stderr_stream: ?*io.OutStream(os.File.WriteError) = null;
 var stderr_mutex = std.Mutex.init();
 pub fn warn(comptime fmt: []const u8, args: ...) void {
     const held = stderr_mutex.acquire();
@@ -46,12 +46,12 @@ pub fn warn(comptime fmt: []const u8, args: ...) void {
     stderr.print(fmt, args) catch return;
 }
 
-pub fn getStderrStream() !*io.OutStream(io.FileOutStream.Error) {
+pub fn getStderrStream() !*io.OutStream(os.File.WriteError) {
     if (stderr_stream) |st| {
         return st;
     } else {
         stderr_file = try io.getStdErr();
-        stderr_file_out_stream = io.FileOutStream.init(stderr_file);
+        stderr_file_out_stream = stderr_file.outStream();
         const st = &stderr_file_out_stream.stream;
         stderr_stream = st;
         return st;
@@ -876,7 +876,7 @@ fn openSelfDebugInfoLinux(allocator: *mem.Allocator) !DebugInfo {
 }
 
 pub fn findElfSection(elf: *Elf, name: []const u8) ?*elf.Shdr {
-    var file_stream = io.FileInStream.init(elf.in_file);
+    var file_stream = elf.in_file.inStream();
     const in = &file_stream.stream;
 
     section_loop: for (elf.section_headers) |*elf_section| {
@@ -1068,7 +1068,7 @@ pub const DebugInfo = switch (builtin.os) {
         }
 
         pub fn readString(self: *DebugInfo) ![]u8 {
-            var in_file_stream = io.FileInStream.init(self.self_exe_file);
+            var in_file_stream = self.self_exe_file.inStream();
             const in_stream = &in_file_stream.stream;
             return readStringRaw(self.allocator(), in_stream);
         }
@@ -1405,7 +1405,7 @@ fn parseFormValue(allocator: *mem.Allocator, in_stream: var, form_id: u64, is_64
 
 fn parseAbbrevTable(st: *DebugInfo) !AbbrevTable {
     const in_file = st.self_exe_file;
-    var in_file_stream = io.FileInStream.init(in_file);
+    var in_file_stream = in_file.inStream();
     const in_stream = &in_file_stream.stream;
     var result = AbbrevTable.init(st.allocator());
     while (true) {
@@ -1456,7 +1456,7 @@ fn getAbbrevTableEntry(abbrev_table: *const AbbrevTable, abbrev_code: u64) ?*con
 
 fn parseDie(st: *DebugInfo, abbrev_table: *const AbbrevTable, is_64: bool) !Die {
     const in_file = st.self_exe_file;
-    var in_file_stream = io.FileInStream.init(in_file);
+    var in_file_stream = in_file.inStream();
     const in_stream = &in_file_stream.stream;
     const abbrev_code = try readULeb128(in_stream);
     const table_entry = getAbbrevTableEntry(abbrev_table, abbrev_code) orelse return error.InvalidDebugInfo;
@@ -1682,7 +1682,7 @@ fn getLineNumberInfoLinux(di: *DebugInfo, compile_unit: *const CompileUnit, targ
     var this_offset = di.debug_line.offset;
     var this_index: usize = 0;
 
-    var in_file_stream = io.FileInStream.init(in_file);
+    var in_file_stream = in_file.inStream();
     const in_stream = &in_file_stream.stream;
 
     while (this_offset < debug_line_end) : (this_index += 1) {
@@ -1857,7 +1857,7 @@ fn scanAllCompileUnits(st: *DebugInfo) !void {
     var this_unit_offset = st.debug_info.offset;
     var cu_index: usize = 0;
 
-    var in_file_stream = io.FileInStream.init(st.self_exe_file);
+    var in_file_stream = st.self_exe_file.inStream();
     const in_stream = &in_file_stream.stream;
 
     while (this_unit_offset < debug_info_end) {
@@ -1923,7 +1923,7 @@ fn scanAllCompileUnits(st: *DebugInfo) !void {
 }
 
 fn findCompileUnit(st: *DebugInfo, target_address: u64) !*const CompileUnit {
-    var in_file_stream = io.FileInStream.init(st.self_exe_file);
+    var in_file_stream = st.self_exe_file.inStream();
     const in_stream = &in_file_stream.stream;
     for (st.compile_unit_list.toSlice()) |*compile_unit| {
         if (compile_unit.pc_range) |range| {
std/event/fs.zig
@@ -1246,9 +1246,7 @@ pub fn Watch(comptime V: type) type {
                             os.linux.EPOLLET | os.linux.EPOLLIN,
                         ) catch unreachable)) catch |err| {
                             const transformed_err = switch (err) {
-                                error.InvalidFileDescriptor => unreachable,
                                 error.FileDescriptorAlreadyPresentInSet => unreachable,
-                                error.InvalidSyscall => unreachable,
                                 error.OperationCausesCircularLoop => unreachable,
                                 error.FileDescriptorNotRegistered => unreachable,
                                 error.SystemResources => error.SystemResources,
std/event/io.zig
@@ -0,0 +1,48 @@
+const std = @import("../index.zig");
+const builtin = @import("builtin");
+const Allocator = std.mem.Allocator;
+const assert = std.debug.assert;
+
+pub fn InStream(comptime ReadError: type) type {
+    return struct {
+        const Self = @This();
+        pub const Error = ReadError;
+
+        /// Return the number of bytes read. It may be less than buffer.len.
+        /// If the number of bytes read is 0, it means end of stream.
+        /// End of stream is not an error condition.
+        readFn: async<*Allocator> fn (self: *Self, buffer: []u8) Error!usize,
+
+        /// Return the number of bytes read. It may be less than buffer.len.
+        /// If the number of bytes read is 0, it means end of stream.
+        /// End of stream is not an error condition.
+        pub async fn read(self: *Self, buffer: []u8) !usize {
+            return await (async self.readFn(self, buffer) catch unreachable);
+        }
+
+        /// Same as `read` but end of stream returns `error.EndOfStream`.
+        pub async fn readFull(self: *Self, buf: []u8) !void {
+            var index: usize = 0;
+            while (index != buf.len) {
+                const amt_read = try await (async self.read(buf[index..]) catch unreachable);
+                if (amt_read == 0) return error.EndOfStream;
+                index += amt_read;
+            }
+        }
+
+        pub async fn readStruct(self: *Self, comptime T: type, ptr: *T) !void {
+            // Only extern and packed structs have defined in-memory layout.
+            comptime assert(@typeInfo(T).Struct.layout != builtin.TypeInfo.ContainerLayout.Auto);
+            return await (async self.readFull(@sliceToBytes((*[1]T)(ptr)[0..])) catch unreachable);
+        }
+    };
+}
+
+pub fn OutStream(comptime WriteError: type) type {
+    return struct {
+        const Self = @This();
+        pub const Error = WriteError;
+
+        writeFn: async<*Allocator> fn (self: *Self, buffer: []u8) Error!void,
+    };
+}
std/event/net.zig
@@ -3,12 +3,12 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const event = std.event;
 const mem = std.mem;
-const posix = std.os.posix;
-const windows = std.os.windows;
+const os = std.os;
+const posix = os.posix;
 const Loop = std.event.Loop;
 
 pub const Server = struct {
-    handleRequestFn: async<*mem.Allocator> fn (*Server, *const std.net.Address, *const std.os.File) void,
+    handleRequestFn: async<*mem.Allocator> fn (*Server, *const std.net.Address, *const os.File) void,
 
     loop: *Loop,
     sockfd: ?i32,
@@ -40,17 +40,17 @@ pub const Server = struct {
     pub fn listen(
         self: *Server,
         address: *const std.net.Address,
-        handleRequestFn: async<*mem.Allocator> fn (*Server, *const std.net.Address, *const std.os.File) void,
+        handleRequestFn: async<*mem.Allocator> fn (*Server, *const std.net.Address, *const os.File) void,
     ) !void {
         self.handleRequestFn = handleRequestFn;
 
-        const sockfd = try std.os.posixSocket(posix.AF_INET, posix.SOCK_STREAM | posix.SOCK_CLOEXEC | posix.SOCK_NONBLOCK, posix.PROTO_tcp);
-        errdefer std.os.close(sockfd);
+        const sockfd = try os.posixSocket(posix.AF_INET, posix.SOCK_STREAM | posix.SOCK_CLOEXEC | posix.SOCK_NONBLOCK, posix.PROTO_tcp);
+        errdefer os.close(sockfd);
         self.sockfd = sockfd;
 
-        try std.os.posixBind(sockfd, &address.os_addr);
-        try std.os.posixListen(sockfd, posix.SOMAXCONN);
-        self.listen_address = std.net.Address.initPosix(try std.os.posixGetSockName(sockfd));
+        try os.posixBind(sockfd, &address.os_addr);
+        try os.posixListen(sockfd, posix.SOMAXCONN);
+        self.listen_address = std.net.Address.initPosix(try os.posixGetSockName(sockfd));
 
         self.accept_coro = try async<self.loop.allocator> Server.handler(self);
         errdefer cancel self.accept_coro.?;
@@ -63,19 +63,25 @@ pub const Server = struct {
     /// Stop listening
     pub fn close(self: *Server) void {
         self.loop.linuxRemoveFd(self.sockfd.?);
-        std.os.close(self.sockfd.?);
+        os.close(self.sockfd.?);
     }
 
     pub fn deinit(self: *Server) void {
         if (self.accept_coro) |accept_coro| cancel accept_coro;
-        if (self.sockfd) |sockfd| std.os.close(sockfd);
+        if (self.sockfd) |sockfd| os.close(sockfd);
     }
 
     pub async fn handler(self: *Server) void {
         while (true) {
             var accepted_addr: std.net.Address = undefined;
-            if (std.os.posixAccept(self.sockfd.?, &accepted_addr.os_addr, posix.SOCK_NONBLOCK | posix.SOCK_CLOEXEC)) |accepted_fd| {
-                var socket = std.os.File.openHandle(accepted_fd);
+            // TODO just inline the following function here and don't expose it as posixAsyncAccept
+            if (os.posixAsyncAccept(self.sockfd.?, &accepted_addr.os_addr, posix.SOCK_NONBLOCK | posix.SOCK_CLOEXEC)) |accepted_fd| {
+                if (accepted_fd == -1) {
+                    // would block
+                    suspend; // we will get resumed by epoll_wait in the event loop
+                    continue;
+                }
+                var socket = os.File.openHandle(accepted_fd);
                 _ = async<self.loop.allocator> self.handleRequestFn(self, accepted_addr, socket) catch |err| switch (err) {
                     error.OutOfMemory => {
                         socket.close();
@@ -83,22 +89,16 @@ pub const Server = struct {
                     },
                 };
             } else |err| switch (err) {
-                error.WouldBlock => {
-                    suspend; // we will get resumed by epoll_wait in the event loop
-                    continue;
-                },
                 error.ProcessFdQuotaExceeded => {
-                    errdefer std.os.emfile_promise_queue.remove(&self.waiting_for_emfile_node);
+                    errdefer os.emfile_promise_queue.remove(&self.waiting_for_emfile_node);
                     suspend {
                         self.waiting_for_emfile_node = PromiseNode.init(@handle());
-                        std.os.emfile_promise_queue.append(&self.waiting_for_emfile_node);
+                        os.emfile_promise_queue.append(&self.waiting_for_emfile_node);
                     }
                     continue;
                 },
-                error.ConnectionAborted, error.FileDescriptorClosed => continue,
+                error.ConnectionAborted => continue,
 
-                error.PageFault => unreachable,
-                error.InvalidSyscall => unreachable,
                 error.FileDescriptorNotASocket => unreachable,
                 error.OperationNotSupported => unreachable,
 
@@ -111,64 +111,161 @@ pub const Server = struct {
 };
 
 pub async fn connectUnixSocket(loop: *Loop, path: []const u8) !i32 {
-    const sockfd = try std.os.posixSocket(
+    const sockfd = try os.posixSocket(
         posix.AF_UNIX,
         posix.SOCK_STREAM | posix.SOCK_CLOEXEC | posix.SOCK_NONBLOCK,
         0,
     );
-    errdefer std.os.close(sockfd);
+    errdefer os.close(sockfd);
 
-    var sock_addr = posix.sockaddr{
-        .un = posix.sockaddr_un{
-            .family = posix.AF_UNIX,
-            .path = undefined,
-        },
+    var sock_addr = posix.sockaddr_un{
+        .family = posix.AF_UNIX,
+        .path = undefined,
     };
 
-    if (path.len > @typeOf(sock_addr.un.path).len) return error.NameTooLong;
-    mem.copy(u8, sock_addr.un.path[0..], path);
+    if (path.len > @typeOf(sock_addr.path).len) return error.NameTooLong;
+    mem.copy(u8, sock_addr.path[0..], path);
     const size = @intCast(u32, @sizeOf(posix.sa_family_t) + path.len);
-    try std.os.posixConnectAsync(sockfd, &sock_addr, size);
+    try os.posixConnectAsync(sockfd, &sock_addr, size);
     try await try async loop.linuxWaitFd(sockfd, posix.EPOLLIN | posix.EPOLLOUT | posix.EPOLLET);
-    try std.os.posixGetSockOptConnectError(sockfd);
+    try os.posixGetSockOptConnectError(sockfd);
 
     return sockfd;
 }
 
-pub async fn socketRead(loop: *std.event.Loop, fd: i32, buffer: []u8) !void {
+pub const ReadError = error{
+    SystemResources,
+    Unexpected,
+    UserResourceLimitReached,
+    InputOutput,
+
+    FileDescriptorNotRegistered, // TODO remove this possibility
+    OperationCausesCircularLoop, // TODO remove this possibility
+    FileDescriptorAlreadyPresentInSet, // TODO remove this possibility
+    FileDescriptorIncompatibleWithEpoll, // TODO remove this possibility
+};
+
+/// returns number of bytes read. 0 means EOF.
+pub async fn read(loop: *std.event.Loop, fd: os.FileHandle, buffer: []u8) ReadError!usize {
+    const iov = posix.iovec{
+        .iov_base = buffer.ptr,
+        .iov_len = buffer.len,
+    };
+    const iovs: *const [1]posix.iovec = &iov;
+    return await (async readvPosix(loop, fd, iovs, 1) catch unreachable);
+}
+
+pub const WriteError = error{};
+
+pub async fn write(loop: *std.event.Loop, fd: os.FileHandle, buffer: []const u8) WriteError!void {
+    const iov = posix.iovec_const{
+        .iov_base = buffer.ptr,
+        .iov_len = buffer.len,
+    };
+    const iovs: *const [1]posix.iovec_const = &iov;
+    return await (async writevPosix(loop, fd, iovs, 1) catch unreachable);
+}
+
+pub async fn writevPosix(loop: *Loop, fd: i32, iov: [*]const posix.iovec_const, count: usize) !void {
     while (true) {
-        return std.os.posixRead(fd, buffer) catch |err| switch (err) {
-            error.WouldBlock => {
-                try await try async loop.linuxWaitFd(fd, std.os.posix.EPOLLET | std.os.posix.EPOLLIN);
-                continue;
+        switch (builtin.os) {
+            builtin.Os.macosx, builtin.Os.linux => {
+                const rc = posix.writev(fd, iov, count);
+                const err = posix.getErrno(rc);
+                switch (err) {
+                    0 => return,
+                    posix.EINTR => continue,
+                    posix.ESPIPE => unreachable,
+                    posix.EINVAL => unreachable,
+                    posix.EFAULT => unreachable,
+                    posix.EAGAIN => {
+                        try await (async loop.linuxWaitFd(fd, posix.EPOLLET | posix.EPOLLOUT) catch unreachable);
+                        continue;
+                    },
+                    posix.EBADF => unreachable, // always a race condition
+                    posix.EDESTADDRREQ => unreachable, // connect was never called
+                    posix.EDQUOT => unreachable,
+                    posix.EFBIG => unreachable,
+                    posix.EIO => return error.InputOutput,
+                    posix.ENOSPC => unreachable,
+                    posix.EPERM => return error.AccessDenied,
+                    posix.EPIPE => unreachable,
+                    else => return os.unexpectedErrorPosix(err),
+                }
             },
-            else => return err,
-        };
+            else => @compileError("Unsupported OS"),
+        }
     }
 }
-pub async fn socketWrite(loop: *std.event.Loop, fd: i32, buffer: []const u8) !void {
+
+/// returns number of bytes read. 0 means EOF.
+pub async fn readvPosix(loop: *std.event.Loop, fd: i32, iov: [*]posix.iovec, count: usize) !usize {
     while (true) {
-        return std.os.posixWrite(fd, buffer) catch |err| switch (err) {
-            error.WouldBlock => {
-                try await try async loop.linuxWaitFd(fd, std.os.posix.EPOLLET | std.os.posix.EPOLLOUT);
-                continue;
+        switch (builtin.os) {
+            builtin.Os.linux, builtin.Os.freebsd, builtin.Os.macosx => {
+                const rc = posix.readv(fd, iov, count);
+                const err = posix.getErrno(rc);
+                switch (err) {
+                    0 => return rc,
+                    posix.EINTR => continue,
+                    posix.EINVAL => unreachable,
+                    posix.EFAULT => unreachable,
+                    posix.EAGAIN => {
+                        try await (async loop.linuxWaitFd(fd, posix.EPOLLET | posix.EPOLLIN) catch unreachable);
+                        continue;
+                    },
+                    posix.EBADF => unreachable, // always a race condition
+                    posix.EIO => return error.InputOutput,
+                    posix.EISDIR => unreachable,
+                    posix.ENOBUFS => return error.SystemResources,
+                    posix.ENOMEM => return error.SystemResources,
+                    else => return os.unexpectedErrorPosix(err),
+                }
             },
-            else => return err,
+            else => @compileError("Unsupported OS"),
+        }
+    }
+}
+
+pub async fn writev(loop: *Loop, fd: os.FileHandle, data: []const []const u8) !void {
+    const iovecs = try loop.allocator.alloc(os.posix.iovec_const, data.len);
+    defer loop.allocator.free(iovecs);
+
+    for (data) |buf, i| {
+        iovecs[i] = os.posix.iovec_const{
+            .iov_base = buf.ptr,
+            .iov_len = buf.len,
         };
     }
+
+    return await (async writevPosix(loop, fd, iovecs.ptr, data.len) catch unreachable);
+}
+
+pub async fn readv(loop: *Loop, fd: os.FileHandle, data: []const []u8) !usize {
+    const iovecs = try loop.allocator.alloc(os.posix.iovec, data.len);
+    defer loop.allocator.free(iovecs);
+
+    for (data) |buf, i| {
+        iovecs[i] = os.posix.iovec{
+            .iov_base = buf.ptr,
+            .iov_len = buf.len,
+        };
+    }
+
+    return await (async readvPosix(loop, fd, iovecs.ptr, data.len) catch unreachable);
 }
 
-pub async fn connect(loop: *Loop, _address: *const std.net.Address) !std.os.File {
-    var address = _address.*; // TODO https://github.com/ziglang/zig/issues/733
+pub async fn connect(loop: *Loop, _address: *const std.net.Address) !os.File {
+    var address = _address.*; // TODO https://github.com/ziglang/zig/issues/1592
 
-    const sockfd = try std.os.posixSocket(posix.AF_INET, posix.SOCK_STREAM | posix.SOCK_CLOEXEC | posix.SOCK_NONBLOCK, posix.PROTO_tcp);
-    errdefer std.os.close(sockfd);
+    const sockfd = try os.posixSocket(posix.AF_INET, posix.SOCK_STREAM | posix.SOCK_CLOEXEC | posix.SOCK_NONBLOCK, posix.PROTO_tcp);
+    errdefer os.close(sockfd);
 
-    try std.os.posixConnectAsync(sockfd, &address.os_addr, @sizeOf(posix.sockaddr_in));
+    try os.posixConnectAsync(sockfd, &address.os_addr, @sizeOf(posix.sockaddr_in));
     try await try async loop.linuxWaitFd(sockfd, posix.EPOLLIN | posix.EPOLLOUT | posix.EPOLLET);
-    try std.os.posixGetSockOptConnectError(sockfd);
+    try os.posixGetSockOptConnectError(sockfd);
 
-    return std.os.File.openHandle(sockfd);
+    return os.File.openHandle(sockfd);
 }
 
 test "listen on a port, send bytes, receive bytes" {
@@ -181,9 +278,9 @@ test "listen on a port, send bytes, receive bytes" {
         tcp_server: Server,
 
         const Self = @This();
-        async<*mem.Allocator> fn handler(tcp_server: *Server, _addr: *const std.net.Address, _socket: *const std.os.File) void {
+        async<*mem.Allocator> fn handler(tcp_server: *Server, _addr: *const std.net.Address, _socket: *const os.File) void {
             const self = @fieldParentPtr(Self, "tcp_server", tcp_server);
-            var socket = _socket.*; // TODO https://github.com/ziglang/zig/issues/733
+            var socket = _socket.*; // TODO https://github.com/ziglang/zig/issues/1592
             defer socket.close();
             // TODO guarantee elision of this allocation
             const next_handler = async errorableHandler(self, _addr, socket) catch unreachable;
@@ -194,12 +291,11 @@ test "listen on a port, send bytes, receive bytes" {
                 cancel @handle();
             }
         }
-        async fn errorableHandler(self: *Self, _addr: *const std.net.Address, _socket: std.os.File) !void {
-            const addr = _addr.*; // TODO https://github.com/ziglang/zig/issues/733
-            var socket = _socket; // TODO https://github.com/ziglang/zig/issues/733
+        async fn errorableHandler(self: *Self, _addr: *const std.net.Address, _socket: os.File) !void {
+            const addr = _addr.*; // TODO https://github.com/ziglang/zig/issues/1592
+            var socket = _socket; // TODO https://github.com/ziglang/zig/issues/1592
 
-            var adapter = std.io.FileOutStream.init(socket);
-            var stream = &adapter.stream;
+            const stream = &socket.outStream().stream;
             try stream.print("hello from server\n");
         }
     };
@@ -230,3 +326,47 @@ async fn doAsyncTest(loop: *Loop, address: *const std.net.Address, server: *Serv
     assert(mem.eql(u8, msg, "hello from server\n"));
     server.close();
 }
+
+pub const OutStream = struct {
+    fd: os.FileHandle,
+    stream: Stream,
+    loop: *Loop,
+
+    pub const Error = WriteError;
+    pub const Stream = event.io.OutStream(Error);
+
+    pub fn init(loop: *Loop, fd: os.FileHandle) OutStream {
+        return OutStream{
+            .fd = fd,
+            .loop = loop,
+            .stream = Stream{ .writeFn = writeFn },
+        };
+    }
+
+    async<*mem.Allocator> fn writeFn(out_stream: *Stream, bytes: []const u8) Error!void {
+        const self = @fieldParentPtr(OutStream, "stream", out_stream);
+        return await (async write(self.loop, self.fd, bytes) catch unreachable);
+    }
+};
+
+pub const InStream = struct {
+    fd: os.FileHandle,
+    stream: Stream,
+    loop: *Loop,
+
+    pub const Error = ReadError;
+    pub const Stream = event.io.InStream(Error);
+
+    pub fn init(loop: *Loop, fd: os.FileHandle) InStream {
+        return InStream{
+            .fd = fd,
+            .loop = loop,
+            .stream = Stream{ .readFn = readFn },
+        };
+    }
+
+    async<*mem.Allocator> fn readFn(in_stream: *Stream, bytes: []u8) Error!usize {
+        const self = @fieldParentPtr(InStream, "stream", in_stream);
+        return await (async read(self.loop, self.fd, bytes) catch unreachable);
+    }
+};
std/os/linux/index.zig
@@ -793,6 +793,14 @@ pub fn preadv(fd: i32, iov: [*]const iovec, count: usize, offset: u64) usize {
     return syscall4(SYS_preadv, @intCast(usize, fd), @ptrToInt(iov), count, offset);
 }
 
+pub fn readv(fd: i32, iov: [*]const iovec, count: usize) usize {
+    return syscall3(SYS_readv, @intCast(usize, fd), @ptrToInt(iov), count);
+}
+
+pub fn writev(fd: i32, iov: [*]const iovec_const, count: usize) usize {
+    return syscall3(SYS_writev, @intCast(usize, fd), @ptrToInt(iov), count);
+}
+
 pub fn pwritev(fd: i32, iov: [*]const iovec_const, count: usize, offset: u64) usize {
     return syscall4(SYS_pwritev, @intCast(usize, fd), @ptrToInt(iov), count, offset);
 }
std/os/child_process.zig
@@ -211,8 +211,8 @@ pub const ChildProcess = struct {
         defer Buffer.deinit(&stdout);
         defer Buffer.deinit(&stderr);
 
-        var stdout_file_in_stream = io.FileInStream.init(child.stdout.?);
-        var stderr_file_in_stream = io.FileInStream.init(child.stderr.?);
+        var stdout_file_in_stream = child.stdout.?.inStream();
+        var stderr_file_in_stream = child.stderr.?.inStream();
 
         try stdout_file_in_stream.stream.readAllBuffer(&stdout, max_output_size);
         try stderr_file_in_stream.stream.readAllBuffer(&stderr, max_output_size);
std/os/file.zig
@@ -1,6 +1,7 @@
 const std = @import("../index.zig");
 const builtin = @import("builtin");
 const os = std.os;
+const io = std.io;
 const mem = std.mem;
 const math = std.math;
 const assert = std.debug.assert;
@@ -368,7 +369,6 @@ pub const File = struct {
         FileClosed,
         InputOutput,
         IsDir,
-        WouldBlock,
         SystemResources,
 
         Unexpected,
@@ -385,7 +385,7 @@ pub const File = struct {
                         posix.EINTR => continue,
                         posix.EINVAL => unreachable,
                         posix.EFAULT => unreachable,
-                        posix.EAGAIN => return error.WouldBlock,
+                        posix.EAGAIN => unreachable,
                         posix.EBADF => return error.FileClosed,
                         posix.EIO => return error.InputOutput,
                         posix.EISDIR => return error.IsDir,
@@ -431,4 +431,46 @@ pub const File = struct {
             @compileError("Unsupported OS");
         }
     }
+
+    pub fn inStream(file: File) InStream {
+        return InStream{
+            .file = file,
+            .stream = InStream.Stream{ .readFn = InStream.readFn },
+        };
+    }
+
+    pub fn outStream(file: File) OutStream {
+        return OutStream{
+            .file = file,
+            .stream = OutStream.Stream{ .writeFn = OutStream.writeFn },
+        };
+    }
+
+    /// Implementation of io.InStream trait for File
+    pub const InStream = struct {
+        file: File,
+        stream: Stream,
+
+        pub const Error = ReadError;
+        pub const Stream = io.InStream(Error);
+
+        fn readFn(in_stream: *Stream, buffer: []u8) Error!usize {
+            const self = @fieldParentPtr(InStream, "stream", in_stream);
+            return self.file.read(buffer);
+        }
+    };
+
+    /// Implementation of io.OutStream trait for File
+    pub const OutStream = struct {
+        file: File,
+        stream: Stream,
+
+        pub const Error = WriteError;
+        pub const Stream = io.OutStream(Error);
+
+        fn writeFn(out_stream: *Stream, bytes: []const u8) Error!void {
+            const self = @fieldParentPtr(OutStream, "stream", out_stream);
+            return self.file.write(bytes);
+        }
+    };
 };
std/os/index.zig
@@ -242,8 +242,8 @@ pub fn posixRead(fd: i32, buf: []u8) !void {
             return switch (err) {
                 posix.EINTR => continue,
                 posix.EINVAL, posix.EFAULT => unreachable,
-                posix.EAGAIN => error.WouldBlock,
-                posix.EBADF => error.FileClosed,
+                posix.EAGAIN => unreachable,
+                posix.EBADF => unreachable, // always a race condition
                 posix.EIO => error.InputOutput,
                 posix.EISDIR => error.IsDir,
                 posix.ENOBUFS, posix.ENOMEM => error.SystemResources,
@@ -284,8 +284,8 @@ pub fn posix_preadv(fd: i32, iov: [*]const posix.iovec, count: usize, offset: u6
                     posix.EINVAL => unreachable,
                     posix.EFAULT => unreachable,
                     posix.ESPIPE => unreachable, // fd is not seekable
-                    posix.EAGAIN => return error.WouldBlock,
-                    posix.EBADF => return error.FileClosed,
+                    posix.EAGAIN => unreachable, // use posixAsyncPReadV for non blocking
+                    posix.EBADF => unreachable, // always a race condition
                     posix.EIO => return error.InputOutput,
                     posix.EISDIR => return error.IsDir,
                     posix.ENOBUFS => return error.SystemResources,
@@ -302,8 +302,8 @@ pub fn posix_preadv(fd: i32, iov: [*]const posix.iovec, count: usize, offset: u6
                 posix.EINTR => continue,
                 posix.EINVAL => unreachable,
                 posix.EFAULT => unreachable,
-                posix.EAGAIN => return error.WouldBlock,
-                posix.EBADF => return error.FileClosed,
+                posix.EAGAIN => unreachable, // use posixAsyncPReadV for non blocking
+                posix.EBADF => unreachable, // always a race condition
                 posix.EIO => return error.InputOutput,
                 posix.EISDIR => return error.IsDir,
                 posix.ENOBUFS => return error.SystemResources,
@@ -316,9 +316,6 @@ pub fn posix_preadv(fd: i32, iov: [*]const posix.iovec, count: usize, offset: u6
 }
 
 pub const PosixWriteError = error{
-    WouldBlock,
-    FileClosed,
-    DestinationAddressRequired,
     DiskQuota,
     FileTooBig,
     InputOutput,
@@ -349,9 +346,9 @@ pub fn posixWrite(fd: i32, bytes: []const u8) !void {
             posix.EINTR => continue,
             posix.EINVAL => unreachable,
             posix.EFAULT => unreachable,
-            posix.EAGAIN => return PosixWriteError.WouldBlock,
-            posix.EBADF => return PosixWriteError.FileClosed,
-            posix.EDESTADDRREQ => return PosixWriteError.DestinationAddressRequired,
+            posix.EAGAIN => unreachable, // use posixAsyncWrite for non-blocking
+            posix.EBADF => unreachable, // always a race condition
+            posix.EDESTADDRREQ => unreachable, // connect was never called
             posix.EDQUOT => return PosixWriteError.DiskQuota,
             posix.EFBIG => return PosixWriteError.FileTooBig,
             posix.EIO => return PosixWriteError.InputOutput,
@@ -391,9 +388,9 @@ pub fn posix_pwritev(fd: i32, iov: [*]const posix.iovec_const, count: usize, off
                     posix.ESPIPE => unreachable, // fd is not seekable
                     posix.EINVAL => unreachable,
                     posix.EFAULT => unreachable,
-                    posix.EAGAIN => return PosixWriteError.WouldBlock,
-                    posix.EBADF => return PosixWriteError.FileClosed,
-                    posix.EDESTADDRREQ => return PosixWriteError.DestinationAddressRequired,
+                    posix.EAGAIN => unreachable, // use posixAsyncPWriteV for non-blocking
+                    posix.EBADF => unreachable, // always a race condition
+                    posix.EDESTADDRREQ => unreachable, // connect was never called
                     posix.EDQUOT => return PosixWriteError.DiskQuota,
                     posix.EFBIG => return PosixWriteError.FileTooBig,
                     posix.EIO => return PosixWriteError.InputOutput,
@@ -412,9 +409,9 @@ pub fn posix_pwritev(fd: i32, iov: [*]const posix.iovec_const, count: usize, off
                 posix.EINTR => continue,
                 posix.EINVAL => unreachable,
                 posix.EFAULT => unreachable,
-                posix.EAGAIN => return PosixWriteError.WouldBlock,
-                posix.EBADF => return PosixWriteError.FileClosed,
-                posix.EDESTADDRREQ => return PosixWriteError.DestinationAddressRequired,
+                posix.EAGAIN => unreachable, // use posixAsyncPWriteV for non-blocking
+                posix.EBADF => unreachable, // always a race condition
+                posix.EDESTADDRREQ => unreachable, // connect was never called
                 posix.EDQUOT => return PosixWriteError.DiskQuota,
                 posix.EFBIG => return PosixWriteError.FileTooBig,
                 posix.EIO => return PosixWriteError.InputOutput,
@@ -2287,22 +2284,9 @@ pub const PosixBindError = error{
     /// use.  See the discussion of /proc/sys/net/ipv4/ip_local_port_range ip(7).
     AddressInUse,
 
-    /// sockfd is not a valid file descriptor.
-    InvalidFileDescriptor,
-
-    /// The socket is already bound to an address, or addrlen is wrong, or addr is not
-    /// a valid address for this socket's domain.
-    InvalidSocketOrAddress,
-
-    /// The file descriptor sockfd does not refer to a socket.
-    FileDescriptorNotASocket,
-
     /// A nonexistent interface was requested or the requested address was not local.
     AddressNotAvailable,
 
-    /// addr points outside the user's accessible address space.
-    PageFault,
-
     /// Too many symbolic links were encountered in resolving addr.
     SymLinkLoop,
 
@@ -2333,11 +2317,11 @@ pub fn posixBind(fd: i32, addr: *const posix.sockaddr) PosixBindError!void {
         0 => return,
         posix.EACCES => return PosixBindError.AccessDenied,
         posix.EADDRINUSE => return PosixBindError.AddressInUse,
-        posix.EBADF => return PosixBindError.InvalidFileDescriptor,
-        posix.EINVAL => return PosixBindError.InvalidSocketOrAddress,
-        posix.ENOTSOCK => return PosixBindError.FileDescriptorNotASocket,
+        posix.EBADF => unreachable, // always a race condition if this error is returned
+        posix.EINVAL => unreachable,
+        posix.ENOTSOCK => unreachable,
         posix.EADDRNOTAVAIL => return PosixBindError.AddressNotAvailable,
-        posix.EFAULT => return PosixBindError.PageFault,
+        posix.EFAULT => unreachable,
         posix.ELOOP => return PosixBindError.SymLinkLoop,
         posix.ENAMETOOLONG => return PosixBindError.NameTooLong,
         posix.ENOENT => return PosixBindError.FileNotFound,
@@ -2356,9 +2340,6 @@ const PosixListenError = error{
     /// use.  See the discussion of /proc/sys/net/ipv4/ip_local_port_range in ip(7).
     AddressInUse,
 
-    /// The argument sockfd is not a valid file descriptor.
-    InvalidFileDescriptor,
-
     /// The file descriptor sockfd does not refer to a socket.
     FileDescriptorNotASocket,
 
@@ -2375,7 +2356,7 @@ pub fn posixListen(sockfd: i32, backlog: u32) PosixListenError!void {
     switch (err) {
         0 => return,
         posix.EADDRINUSE => return PosixListenError.AddressInUse,
-        posix.EBADF => return PosixListenError.InvalidFileDescriptor,
+        posix.EBADF => unreachable,
         posix.ENOTSOCK => return PosixListenError.FileDescriptorNotASocket,
         posix.EOPNOTSUPP => return PosixListenError.OperationNotSupported,
         else => return unexpectedErrorPosix(err),
@@ -2383,21 +2364,8 @@ pub fn posixListen(sockfd: i32, backlog: u32) PosixListenError!void {
 }
 
 pub const PosixAcceptError = error{
-    /// The  socket  is marked nonblocking and no connections are present to be accepted.
-    WouldBlock,
-
-    /// sockfd is not an open file descriptor.
-    FileDescriptorClosed,
-
     ConnectionAborted,
 
-    /// The addr argument is not in a writable part of the user address space.
-    PageFault,
-
-    /// Socket  is  not  listening for connections, or addrlen is invalid (e.g., is negative),
-    /// or invalid value in flags.
-    InvalidSyscall,
-
     /// The per-process limit on the number of open file descriptors has been reached.
     ProcessFdQuotaExceeded,
 
@@ -2433,14 +2401,15 @@ pub fn posixAccept(fd: i32, addr: *posix.sockaddr, flags: u32) PosixAcceptError!
             posix.EINTR => continue,
             else => return unexpectedErrorPosix(err),
 
-            posix.EAGAIN => return PosixAcceptError.WouldBlock,
-            posix.EBADF => return PosixAcceptError.FileDescriptorClosed,
+            posix.EAGAIN => unreachable, // use posixAsyncAccept for non-blocking
+            posix.EBADF => unreachable, // always a race condition
             posix.ECONNABORTED => return PosixAcceptError.ConnectionAborted,
-            posix.EFAULT => return PosixAcceptError.PageFault,
-            posix.EINVAL => return PosixAcceptError.InvalidSyscall,
+            posix.EFAULT => unreachable,
+            posix.EINVAL => unreachable,
             posix.EMFILE => return PosixAcceptError.ProcessFdQuotaExceeded,
             posix.ENFILE => return PosixAcceptError.SystemFdQuotaExceeded,
-            posix.ENOBUFS, posix.ENOMEM => return PosixAcceptError.SystemResources,
+            posix.ENOBUFS => return PosixAcceptError.SystemResources,
+            posix.ENOMEM => return PosixAcceptError.SystemResources,
             posix.ENOTSOCK => return PosixAcceptError.FileDescriptorNotASocket,
             posix.EOPNOTSUPP => return PosixAcceptError.OperationNotSupported,
             posix.EPROTO => return PosixAcceptError.ProtocolFailure,
@@ -2449,10 +2418,35 @@ pub fn posixAccept(fd: i32, addr: *posix.sockaddr, flags: u32) PosixAcceptError!
     }
 }
 
-pub const LinuxEpollCreateError = error{
-    /// Invalid value specified in flags.
-    InvalidSyscall,
+/// Returns -1 if would block.
+pub fn posixAsyncAccept(fd: i32, addr: *posix.sockaddr, flags: u32) PosixAcceptError!i32 {
+    while (true) {
+        var sockaddr_size = u32(@sizeOf(posix.sockaddr));
+        const rc = posix.accept4(fd, addr, &sockaddr_size, flags);
+        const err = posix.getErrno(rc);
+        switch (err) {
+            0 => return @intCast(i32, rc),
+            posix.EINTR => continue,
+            else => return unexpectedErrorPosix(err),
+
+            posix.EAGAIN => return -1,
+            posix.EBADF => unreachable, // always a race condition
+            posix.ECONNABORTED => return PosixAcceptError.ConnectionAborted,
+            posix.EFAULT => unreachable,
+            posix.EINVAL => unreachable,
+            posix.EMFILE => return PosixAcceptError.ProcessFdQuotaExceeded,
+            posix.ENFILE => return PosixAcceptError.SystemFdQuotaExceeded,
+            posix.ENOBUFS => return PosixAcceptError.SystemResources,
+            posix.ENOMEM => return PosixAcceptError.SystemResources,
+            posix.ENOTSOCK => return PosixAcceptError.FileDescriptorNotASocket,
+            posix.EOPNOTSUPP => return PosixAcceptError.OperationNotSupported,
+            posix.EPROTO => return PosixAcceptError.ProtocolFailure,
+            posix.EPERM => return PosixAcceptError.BlockedByFirewall,
+        }
+    }
+}
 
+pub const LinuxEpollCreateError = error{
     /// The  per-user   limit   on   the   number   of   epoll   instances   imposed   by
     /// /proc/sys/fs/epoll/max_user_instances  was encountered.  See epoll(7) for further
     /// details.
@@ -2476,7 +2470,7 @@ pub fn linuxEpollCreate(flags: u32) LinuxEpollCreateError!i32 {
         0 => return @intCast(i32, rc),
         else => return unexpectedErrorPosix(err),
 
-        posix.EINVAL => return LinuxEpollCreateError.InvalidSyscall,
+        posix.EINVAL => unreachable,
         posix.EMFILE => return LinuxEpollCreateError.ProcessFdQuotaExceeded,
         posix.ENFILE => return LinuxEpollCreateError.SystemFdQuotaExceeded,
         posix.ENOMEM => return LinuxEpollCreateError.SystemResources,
@@ -2484,22 +2478,10 @@ pub fn linuxEpollCreate(flags: u32) LinuxEpollCreateError!i32 {
 }
 
 pub const LinuxEpollCtlError = error{
-    /// epfd or fd is not a valid file descriptor.
-    InvalidFileDescriptor,
-
     /// op was EPOLL_CTL_ADD, and the supplied file descriptor fd is  already  registered
     /// with this epoll instance.
     FileDescriptorAlreadyPresentInSet,
 
-    /// epfd is not an epoll file descriptor, or fd is the same as epfd, or the requested
-    /// operation op is not supported by this interface, or
-    /// An invalid event type was specified along with EPOLLEXCLUSIVE in events, or
-    /// op was EPOLL_CTL_MOD and events included EPOLLEXCLUSIVE, or
-    /// op was EPOLL_CTL_MOD and the EPOLLEXCLUSIVE flag has previously been  applied  to
-    /// this epfd, fd pair, or
-    /// EPOLLEXCLUSIVE was specified in event and fd refers to an epoll instance.
-    InvalidSyscall,
-
     /// fd refers to an epoll instance and this EPOLL_CTL_ADD operation would result in a
     /// circular loop of epoll instances monitoring one another.
     OperationCausesCircularLoop,
@@ -2531,9 +2513,9 @@ pub fn linuxEpollCtl(epfd: i32, op: u32, fd: i32, event: *linux.epoll_event) Lin
         0 => return,
         else => return unexpectedErrorPosix(err),
 
-        posix.EBADF => return LinuxEpollCtlError.InvalidFileDescriptor,
+        posix.EBADF => unreachable, // always a race condition if this happens
         posix.EEXIST => return LinuxEpollCtlError.FileDescriptorAlreadyPresentInSet,
-        posix.EINVAL => return LinuxEpollCtlError.InvalidSyscall,
+        posix.EINVAL => unreachable,
         posix.ELOOP => return LinuxEpollCtlError.OperationCausesCircularLoop,
         posix.ENOENT => return LinuxEpollCtlError.FileDescriptorNotRegistered,
         posix.ENOMEM => return LinuxEpollCtlError.SystemResources,
std/special/build_runner.zig
@@ -48,16 +48,16 @@ pub fn main() !void {
     var prefix: ?[]const u8 = null;
 
     var stderr_file = io.getStdErr();
-    var stderr_file_stream: io.FileOutStream = undefined;
+    var stderr_file_stream: os.File.OutStream = undefined;
     var stderr_stream = if (stderr_file) |f| x: {
-        stderr_file_stream = io.FileOutStream.init(f);
+        stderr_file_stream = f.outStream();
         break :x &stderr_file_stream.stream;
     } else |err| err;
 
     var stdout_file = io.getStdOut();
-    var stdout_file_stream: io.FileOutStream = undefined;
+    var stdout_file_stream: os.File.OutStream = undefined;
     var stdout_stream = if (stdout_file) |f| x: {
-        stdout_file_stream = io.FileOutStream.init(f);
+        stdout_file_stream = f.outStream();
         break :x &stdout_file_stream.stream;
     } else |err| err;
 
std/zig/bench.zig
@@ -24,7 +24,7 @@ pub fn main() !void {
     const mb_per_sec = bytes_per_sec / (1024 * 1024);
 
     var stdout_file = try std.io.getStdOut();
-    const stdout = &std.io.FileOutStream.init(stdout_file).stream;
+    const stdout = &stdout_file.outStream().stream;
     try stdout.print("{.3} MiB/s, {} KiB used \n", mb_per_sec, memory_used / 1024);
 }
 
std/zig/parser_test.zig
@@ -1873,7 +1873,7 @@ var fixed_buffer_mem: [100 * 1024]u8 = undefined;
 
 fn testParse(source: []const u8, allocator: *mem.Allocator, anything_changed: *bool) ![]u8 {
     var stderr_file = try io.getStdErr();
-    var stderr = &io.FileOutStream.init(stderr_file).stream;
+    var stderr = &stderr_file.outStream().stream;
 
     var tree = try std.zig.parse(allocator, source);
     defer tree.deinit();
std/coff.zig
@@ -41,7 +41,7 @@ pub const Coff = struct {
     pub fn loadHeader(self: *Coff) !void {
         const pe_pointer_offset = 0x3C;
 
-        var file_stream = io.FileInStream.init(self.in_file);
+        var file_stream = self.in_file.inStream();
         const in = &file_stream.stream;
 
         var magic: [2]u8 = undefined;
@@ -77,7 +77,7 @@ pub const Coff = struct {
         try self.loadOptionalHeader(&file_stream);
     }
 
-    fn loadOptionalHeader(self: *Coff, file_stream: *io.FileInStream) !void {
+    fn loadOptionalHeader(self: *Coff, file_stream: *os.File.InStream) !void {
         const in = &file_stream.stream;
         self.pe_header.magic = try in.readIntLe(u16);
         // For now we're only interested in finding the reference to the .pdb,
@@ -115,7 +115,7 @@ pub const Coff = struct {
         const file_offset = debug_dir.virtual_address - header.virtual_address + header.pointer_to_raw_data;
         try self.in_file.seekTo(file_offset + debug_dir.size);
 
-        var file_stream = io.FileInStream.init(self.in_file);
+        var file_stream = self.in_file.inStream();
         const in = &file_stream.stream;
 
         var cv_signature: [4]u8 = undefined; // CodeView signature
@@ -146,7 +146,7 @@ pub const Coff = struct {
 
         self.sections = ArrayList(Section).init(self.allocator);
 
-        var file_stream = io.FileInStream.init(self.in_file);
+        var file_stream = self.in_file.inStream();
         const in = &file_stream.stream;
 
         var name: [8]u8 = undefined;
std/elf.zig
@@ -381,7 +381,7 @@ pub const Elf = struct {
         elf.in_file = file;
         elf.auto_close_stream = false;
 
-        var file_stream = io.FileInStream.init(elf.in_file);
+        var file_stream = elf.in_file.inStream();
         const in = &file_stream.stream;
 
         var magic: [4]u8 = undefined;
@@ -525,7 +525,7 @@ pub const Elf = struct {
     }
 
     pub fn findSection(elf: *Elf, name: []const u8) !?*SectionHeader {
-        var file_stream = io.FileInStream.init(elf.in_file);
+        var file_stream = elf.in_file.inStream();
         const in = &file_stream.stream;
 
         section_loop: for (elf.section_headers) |*elf_section| {
std/event.zig
@@ -6,6 +6,7 @@ pub const Locked = @import("event/locked.zig").Locked;
 pub const RwLock = @import("event/rwlock.zig").RwLock;
 pub const RwLocked = @import("event/rwlocked.zig").RwLocked;
 pub const Loop = @import("event/loop.zig").Loop;
+pub const io = @import("event/io.zig");
 pub const fs = @import("event/fs.zig");
 pub const net = @import("event/net.zig");
 
@@ -14,6 +15,7 @@ test "import event tests" {
     _ = @import("event/fs.zig");
     _ = @import("event/future.zig");
     _ = @import("event/group.zig");
+    _ = @import("event/io.zig");
     _ = @import("event/lock.zig");
     _ = @import("event/locked.zig");
     _ = @import("event/rwlock.zig");
std/io.zig
@@ -32,48 +32,6 @@ pub fn getStdIn() GetStdIoErrs!File {
     return File.openHandle(handle);
 }
 
-/// Implementation of InStream trait for File
-pub const FileInStream = struct {
-    file: File,
-    stream: Stream,
-
-    pub const Error = @typeOf(File.read).ReturnType.ErrorSet;
-    pub const Stream = InStream(Error);
-
-    pub fn init(file: File) FileInStream {
-        return FileInStream{
-            .file = file,
-            .stream = Stream{ .readFn = readFn },
-        };
-    }
-
-    fn readFn(in_stream: *Stream, buffer: []u8) Error!usize {
-        const self = @fieldParentPtr(FileInStream, "stream", in_stream);
-        return self.file.read(buffer);
-    }
-};
-
-/// Implementation of OutStream trait for File
-pub const FileOutStream = struct {
-    file: File,
-    stream: Stream,
-
-    pub const Error = File.WriteError;
-    pub const Stream = OutStream(Error);
-
-    pub fn init(file: File) FileOutStream {
-        return FileOutStream{
-            .file = file,
-            .stream = Stream{ .writeFn = writeFn },
-        };
-    }
-
-    fn writeFn(out_stream: *Stream, bytes: []const u8) !void {
-        const self = @fieldParentPtr(FileOutStream, "stream", out_stream);
-        return self.file.write(bytes);
-    }
-};
-
 pub fn InStream(comptime ReadError: type) type {
     return struct {
         const Self = @This();
@@ -280,7 +238,7 @@ pub fn readFileAllocAligned(allocator: *mem.Allocator, path: []const u8, comptim
     const buf = try allocator.alignedAlloc(u8, A, size);
     errdefer allocator.free(buf);
 
-    var adapter = FileInStream.init(file);
+    var adapter = file.inStream();
     try adapter.stream.readNoEof(buf[0..size]);
     return buf;
 }
@@ -577,8 +535,8 @@ pub const BufferOutStream = struct {
 
 pub const BufferedAtomicFile = struct {
     atomic_file: os.AtomicFile,
-    file_stream: FileOutStream,
-    buffered_stream: BufferedOutStream(FileOutStream.Error),
+    file_stream: os.File.OutStream,
+    buffered_stream: BufferedOutStream(os.File.WriteError),
 
     pub fn create(allocator: *mem.Allocator, dest_path: []const u8) !*BufferedAtomicFile {
         // TODO with well defined copy elision we don't need this allocation
@@ -592,8 +550,8 @@ pub const BufferedAtomicFile = struct {
         self.atomic_file = try os.AtomicFile.init(allocator, dest_path, os.File.default_mode);
         errdefer self.atomic_file.deinit();
 
-        self.file_stream = FileOutStream.init(self.atomic_file.file);
-        self.buffered_stream = BufferedOutStream(FileOutStream.Error).init(&self.file_stream.stream);
+        self.file_stream = self.atomic_file.file.outStream();
+        self.buffered_stream = BufferedOutStream(os.File.WriteError).init(&self.file_stream.stream);
         return self;
     }
 
@@ -609,7 +567,7 @@ pub const BufferedAtomicFile = struct {
         try self.atomic_file.finish();
     }
 
-    pub fn stream(self: *BufferedAtomicFile) *OutStream(FileOutStream.Error) {
+    pub fn stream(self: *BufferedAtomicFile) *OutStream(os.File.WriteError) {
         return &self.buffered_stream.stream;
     }
 };
@@ -622,7 +580,7 @@ test "import io tests" {
 
 pub fn readLine(buf: []u8) !usize {
     var stdin = getStdIn() catch return error.StdInUnavailable;
-    var adapter = FileInStream.init(stdin);
+    var adapter = stdin.inStream();
     var stream = &adapter.stream;
     var index: usize = 0;
     while (true) {
@@ -642,3 +600,5 @@ pub fn readLine(buf: []u8) !usize {
         }
     }
 }
+
+
std/io_test.zig
@@ -19,8 +19,8 @@ test "write a file, read it, then delete it" {
         var file = try os.File.openWrite(tmp_file_name);
         defer file.close();
 
-        var file_out_stream = io.FileOutStream.init(file);
-        var buf_stream = io.BufferedOutStream(io.FileOutStream.Error).init(&file_out_stream.stream);
+        var file_out_stream = file.outStream();
+        var buf_stream = io.BufferedOutStream(os.File.WriteError).init(&file_out_stream.stream);
         const st = &buf_stream.stream;
         try st.print("begin");
         try st.write(data[0..]);
@@ -35,8 +35,8 @@ test "write a file, read it, then delete it" {
         const expected_file_size = "begin".len + data.len + "end".len;
         assert(file_size == expected_file_size);
 
-        var file_in_stream = io.FileInStream.init(file);
-        var buf_stream = io.BufferedInStream(io.FileInStream.Error).init(&file_in_stream.stream);
+        var file_in_stream = file.inStream();
+        var buf_stream = io.BufferedInStream(os.File.ReadError).init(&file_in_stream.stream);
         const st = &buf_stream.stream;
         const contents = try st.readAllAlloc(allocator, 2 * 1024);
         defer allocator.free(contents);
std/pdb.zig
@@ -482,7 +482,7 @@ const Msf = struct {
     streams: []MsfStream,
 
     fn openFile(self: *Msf, allocator: *mem.Allocator, file: os.File) !void {
-        var file_stream = io.FileInStream.init(file);
+        var file_stream = file.inStream();
         const in = &file_stream.stream;
 
         var superblock: SuperBlock = undefined;
@@ -597,7 +597,7 @@ const MsfStream = struct {
             .stream = Stream{ .readFn = readFn },
         };
 
-        var file_stream = io.FileInStream.init(file);
+        var file_stream = file.inStream();
         const in = &file_stream.stream;
         try file.seekTo(pos);
 
@@ -627,7 +627,7 @@ const MsfStream = struct {
         var offset = self.pos % self.block_size;
 
         try self.in_file.seekTo(block * self.block_size + offset);
-        var file_stream = io.FileInStream.init(self.in_file);
+        var file_stream = self.in_file.inStream();
         const in = &file_stream.stream;
 
         var size: usize = 0;
test/standalone/brace_expansion/main.zig
@@ -191,7 +191,7 @@ pub fn main() !void {
     var stdin_buf = try Buffer.initSize(global_allocator, 0);
     defer stdin_buf.deinit();
 
-    var stdin_adapter = io.FileInStream.init(stdin_file);
+    var stdin_adapter = stdin_file.inStream();
     try stdin_adapter.stream.readAllBuffer(&stdin_buf, @maxValue(usize));
 
     var result_buf = try Buffer.initSize(global_allocator, 0);
test/compare_output.zig
@@ -19,7 +19,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\
             \\pub fn main() void {
             \\    privateFunction();
-            \\    const stdout = &FileOutStream.init(getStdOut() catch unreachable).stream;
+            \\    const stdout = &(getStdOut() catch unreachable).outStream().stream;
             \\    stdout.print("OK 2\n") catch unreachable;
             \\}
             \\
@@ -34,7 +34,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\// purposefully conflicting function with main.zig
             \\// but it's private so it should be OK
             \\fn privateFunction() void {
-            \\    const stdout = &FileOutStream.init(getStdOut() catch unreachable).stream;
+            \\    const stdout = &(getStdOut() catch unreachable).outStream().stream;
             \\    stdout.print("OK 1\n") catch unreachable;
             \\}
             \\
@@ -60,7 +60,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         tc.addSourceFile("foo.zig",
             \\use @import("std").io;
             \\pub fn foo_function() void {
-            \\    const stdout = &FileOutStream.init(getStdOut() catch unreachable).stream;
+            \\    const stdout = &(getStdOut() catch unreachable).outStream().stream;
             \\    stdout.print("OK\n") catch unreachable;
             \\}
         );
@@ -71,7 +71,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\
             \\pub fn bar_function() void {
             \\    if (foo_function()) {
-            \\        const stdout = &FileOutStream.init(getStdOut() catch unreachable).stream;
+            \\        const stdout = &(getStdOut() catch unreachable).outStream().stream;
             \\        stdout.print("OK\n") catch unreachable;
             \\    }
             \\}
@@ -103,7 +103,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\pub const a_text = "OK\n";
             \\
             \\pub fn ok() void {
-            \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+            \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
             \\    stdout.print(b_text) catch unreachable;
             \\}
         );
@@ -121,7 +121,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\const io = @import("std").io;
         \\
         \\pub fn main() void {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("Hello, world!\n{d4} {x3} {c}\n", u32(12), u16(0x12), u8('a')) catch unreachable;
         \\}
     , "Hello, world!\n0012 012 a\n");
@@ -274,7 +274,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\    var x_local : i32 = print_ok(x);
         \\}
         \\fn print_ok(val: @typeOf(x)) @typeOf(foo) {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("OK\n") catch unreachable;
         \\    return 0;
         \\}
@@ -356,7 +356,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\pub fn main() void {
         \\    const bar = Bar {.field2 = 13,};
         \\    const foo = Foo {.field1 = bar,};
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    if (!foo.method()) {
         \\        stdout.print("BAD\n") catch unreachable;
         \\    }
@@ -370,7 +370,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
     cases.add("defer with only fallthrough",
         \\const io = @import("std").io;
         \\pub fn main() void {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("before\n") catch unreachable;
         \\    defer stdout.print("defer1\n") catch unreachable;
         \\    defer stdout.print("defer2\n") catch unreachable;
@@ -383,7 +383,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\const io = @import("std").io;
         \\const os = @import("std").os;
         \\pub fn main() void {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("before\n") catch unreachable;
         \\    defer stdout.print("defer1\n") catch unreachable;
         \\    defer stdout.print("defer2\n") catch unreachable;
@@ -400,7 +400,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\    do_test() catch return;
         \\}
         \\fn do_test() !void {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("before\n") catch unreachable;
         \\    defer stdout.print("defer1\n") catch unreachable;
         \\    errdefer stdout.print("deferErr\n") catch unreachable;
@@ -419,7 +419,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
         \\    do_test() catch return;
         \\}
         \\fn do_test() !void {
-        \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+        \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
         \\    stdout.print("before\n") catch unreachable;
         \\    defer stdout.print("defer1\n") catch unreachable;
         \\    errdefer stdout.print("deferErr\n") catch unreachable;
@@ -436,7 +436,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\const io = @import("std").io;
             \\
             \\pub fn main() void {
-            \\    const stdout = &io.FileOutStream.init(io.getStdOut() catch unreachable).stream;
+            \\    const stdout = &(io.getStdOut() catch unreachable).outStream().stream;
             \\    stdout.print(foo_txt) catch unreachable;
             \\}
         , "1234\nabcd\n");
@@ -456,7 +456,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\pub fn main() !void {
             \\    var args_it = os.args();
             \\    var stdout_file = try io.getStdOut();
-            \\    var stdout_adapter = io.FileOutStream.init(stdout_file);
+            \\    var stdout_adapter = stdout_file.outStream();
             \\    const stdout = &stdout_adapter.stream;
             \\    var index: usize = 0;
             \\    _ = args_it.skip();
@@ -497,7 +497,7 @@ pub fn addCases(cases: *tests.CompareOutputContext) void {
             \\pub fn main() !void {
             \\    var args_it = os.args();
             \\    var stdout_file = try io.getStdOut();
-            \\    var stdout_adapter = io.FileOutStream.init(stdout_file);
+            \\    var stdout_adapter = stdout_file.outStream();
             \\    const stdout = &stdout_adapter.stream;
             \\    var index: usize = 0;
             \\    _ = args_it.skip();
test/tests.zig
@@ -278,8 +278,8 @@ pub const CompareOutputContext = struct {
             var stdout = Buffer.initNull(b.allocator);
             var stderr = Buffer.initNull(b.allocator);
 
-            var stdout_file_in_stream = io.FileInStream.init(child.stdout.?);
-            var stderr_file_in_stream = io.FileInStream.init(child.stderr.?);
+            var stdout_file_in_stream = child.stdout.?.inStream();
+            var stderr_file_in_stream = child.stderr.?.inStream();
 
             stdout_file_in_stream.stream.readAllBuffer(&stdout, max_stdout_size) catch unreachable;
             stderr_file_in_stream.stream.readAllBuffer(&stderr, max_stdout_size) catch unreachable;
@@ -593,8 +593,8 @@ pub const CompileErrorContext = struct {
             var stdout_buf = Buffer.initNull(b.allocator);
             var stderr_buf = Buffer.initNull(b.allocator);
 
-            var stdout_file_in_stream = io.FileInStream.init(child.stdout.?);
-            var stderr_file_in_stream = io.FileInStream.init(child.stderr.?);
+            var stdout_file_in_stream = child.stdout.?.inStream();
+            var stderr_file_in_stream = child.stderr.?.inStream();
 
             stdout_file_in_stream.stream.readAllBuffer(&stdout_buf, max_stdout_size) catch unreachable;
             stderr_file_in_stream.stream.readAllBuffer(&stderr_buf, max_stdout_size) catch unreachable;
@@ -857,8 +857,8 @@ pub const TranslateCContext = struct {
             var stdout_buf = Buffer.initNull(b.allocator);
             var stderr_buf = Buffer.initNull(b.allocator);
 
-            var stdout_file_in_stream = io.FileInStream.init(child.stdout.?);
-            var stderr_file_in_stream = io.FileInStream.init(child.stderr.?);
+            var stdout_file_in_stream = child.stdout.?.inStream();
+            var stderr_file_in_stream = child.stderr.?.inStream();
 
             stdout_file_in_stream.stream.readAllBuffer(&stdout_buf, max_stdout_size) catch unreachable;
             stderr_file_in_stream.stream.readAllBuffer(&stderr_buf, max_stdout_size) catch unreachable;
CMakeLists.txt
@@ -470,6 +470,7 @@ set(ZIG_STD_FILES
     "event/fs.zig"
     "event/future.zig"
     "event/group.zig"
+    "event/io.zig"
     "event/lock.zig"
     "event/locked.zig"
     "event/loop.zig"