[libc-commits] [libc] [libc] Introduce the ioctl syscall wrapper and port all callers (PR #204640)

[Michael Jones via libc-commits]

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@@ -0,0 +1,52 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Syscall wrapper for ioctl.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_IOCTL_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_IOCTL_H
+
+#include "src/__support/CPP/type_traits/enable_if.h"
+#include "src/__support/CPP/type_traits/is_integral.h"
+#include "src/__support/CPP/type_traits/is_null_pointer.h"
+#include "src/__support/CPP/type_traits/is_pointer.h"
+#include "src/__support/OSUtil/linux/syscall.h" // syscall_checked
+#include "src/__support/error_or.h"
+#include "src/__support/macros/attributes.h" // LIBC_INLINE
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+struct IoctlArg {
+  unsigned long val;
+
+  LIBC_INLINE constexpr IoctlArg() : val(0) {}
+  LIBC_INLINE constexpr IoctlArg(cpp::nullptr_t) : val(0) {}
+
+  template <typename T, cpp::enable_if_t<cpp::is_pointer_v<T>, int> = 0>
+  LIBC_INLINE IoctlArg(T ptr) : val(reinterpret_cast<unsigned long>(ptr)) {}
+
+  template <typename T, cpp::enable_if_t<cpp::is_integral_v<T>, int> = 0>
+  LIBC_INLINE constexpr IoctlArg(T num)
+      : val(static_cast<unsigned long>(num)) {}
+};
+
+LIBC_INLINE ErrorOr<int> ioctl(int fd, unsigned long request,
+                               IoctlArg arg = {}) {
+  return syscall_checked<int>(SYS_ioctl, fd, request, arg.val);
+}
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michaelrj-google wrote:

it might be simpler to phrase this as two overloads, one taking a pointer, and one taking an unsigned long that defaults to 0.

https://github.com/llvm/llvm-project/pull/204640