unix: match ioctl req argument type to libc type

On Solaris, AIX, and zOS, the req argument of ioctl() is a signed int,
not an unsigned long like on other platforms, which means many constants
are negative, causing friction when passing them to a uint argument.
Correct the signature of these functions to pass the req argument as
signed, just like libc.

Fixes golang/go#59030.

Change-Id: Ia14e92a150f4b5fb9488c5032ca296cb786e9811
Reviewed-on: https://go-review.googlesource.com/c/sys/+/476515
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Jason Donenfeld <Jason@zx2c4.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Nahum Shalman <nahamu@gmail.com>

unix/ioctl_signed.go

@@ -0,0 +1,70 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build aix || solaris
+// +build aix solaris
+
+package unix
+
+import (
+	"unsafe"
+)
+
+// ioctl itself should not be exposed directly, but additional get/set
+// functions for specific types are permissible.
+
+// IoctlSetInt performs an ioctl operation which sets an integer value
+// on fd, using the specified request number.
+func IoctlSetInt(fd int, req int, value int) error {
+	return ioctl(fd, req, uintptr(value))
+}
+
+// IoctlSetPointerInt performs an ioctl operation which sets an
+// integer value on fd, using the specified request number. The ioctl
+// argument is called with a pointer to the integer value, rather than
+// passing the integer value directly.
+func IoctlSetPointerInt(fd int, req int, value int) error {
+	v := int32(value)
+	return ioctlPtr(fd, req, unsafe.Pointer(&v))
+}
+
+// IoctlSetWinsize performs an ioctl on fd with a *Winsize argument.
+//
+// To change fd's window size, the req argument should be TIOCSWINSZ.
+func IoctlSetWinsize(fd int, req int, value *Winsize) error {
+	// TODO: if we get the chance, remove the req parameter and
+	// hardcode TIOCSWINSZ.
+	return ioctlPtr(fd, req, unsafe.Pointer(value))
+}
+
+// IoctlSetTermios performs an ioctl on fd with a *Termios.
+//
+// The req value will usually be TCSETA or TIOCSETA.
+func IoctlSetTermios(fd int, req int, value *Termios) error {
+	// TODO: if we get the chance, remove the req parameter.
+	return ioctlPtr(fd, req, unsafe.Pointer(value))
+}
+
+// IoctlGetInt performs an ioctl operation which gets an integer value
+// from fd, using the specified request number.
+//
+// A few ioctl requests use the return value as an output parameter;
+// for those, IoctlRetInt should be used instead of this function.
+func IoctlGetInt(fd int, req int) (int, error) {
+	var value int
+	err := ioctlPtr(fd, req, unsafe.Pointer(&value))
+	return value, err
+}
+
+func IoctlGetWinsize(fd int, req int) (*Winsize, error) {
+	var value Winsize
+	err := ioctlPtr(fd, req, unsafe.Pointer(&value))
+	return &value, err
+}
+
+func IoctlGetTermios(fd int, req int) (*Termios, error) {
+	var value Termios
+	err := ioctlPtr(fd, req, unsafe.Pointer(&value))
+	return &value, err
+}