1 files changed, 43 insertions, 0 deletions
diff --git a/lib/std/io/c_out_stream.zig b/lib/std/io/c_out_stream.zig
new file mode 100644
index 0000000000..8b341e6937
--- /dev/null
+++ b/lib/std/io/c_out_stream.zig
@@ -0,0 +1,43 @@
+const std = @import("../std.zig");
+const os = std.os;
+const OutStream = std.io.OutStream;
+const builtin = @import("builtin");
+
+/// TODO make a proposal to make `std.fs.File` use *FILE when linking libc and this just becomes
+/// std.io.FileOutStream because std.fs.File.write would do this when linking
+/// libc.
+pub const COutStream = struct {
+    pub const Error = std.fs.File.WriteError;
+    pub const Stream = OutStream(Error);
+
+    stream: Stream,
+    c_file: *std.c.FILE,
+
+    pub fn init(c_file: *std.c.FILE) COutStream {
+        return COutStream{
+            .c_file = c_file,
+            .stream = Stream{ .writeFn = writeFn },
+        };
+    }
+
+    fn writeFn(out_stream: *Stream, bytes: []const u8) Error!void {
+        const self = @fieldParentPtr(COutStream, "stream", out_stream);
+        const amt_written = std.c.fwrite(bytes.ptr, 1, bytes.len, self.c_file);
+        if (amt_written == bytes.len) return;
+        switch (std.c._errno().*) {
+            0 => unreachable,
+            os.EINVAL => unreachable,
+            os.EFAULT => unreachable,
+            os.EAGAIN => unreachable, // this is a blocking API
+            os.EBADF => unreachable, // always a race condition
+            os.EDESTADDRREQ => unreachable, // connect was never called
+            os.EDQUOT => return error.DiskQuota,
+            os.EFBIG => return error.FileTooBig,
+            os.EIO => return error.InputOutput,
+            os.ENOSPC => return error.NoSpaceLeft,
+            os.EPERM => return error.AccessDenied,
+            os.EPIPE => return error.BrokenPipe,
+            else => |err| return os.unexpectedErrno(@intCast(usize, err)),
+        }
+    }
+};