[libc-commits] [libc] [libc] Implement fallocate (PR #222843)

[Pavel Labath via libc-commits]

================
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+/// This file contains the declaration of the fallocate, which is the
+/// base syscall wrapper for all fallocate dependent calls.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_FALLOCATE_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_SYSCALL_WRAPPERS_FALLOCATE_H
+
+#include "hdr/errno_macros.h"
+#include "hdr/types/off_t.h"
+#include "src/__support/OSUtil/linux/syscall.h" // For syscall_checked
+#include "src/__support/common.h"
+#include "src/__support/error_or.h"
+#include "src/__support/macros/config.h"
+#include <sys/syscall.h> // For syscall numbers
+
+namespace LIBC_NAMESPACE_DECL {
+namespace linux_syscalls {
+
+LIBC_INLINE ErrorOr<int> fallocate(int fd, int mode, off_t offset, off_t size) {
+#ifdef SYS_fallocate
+#if !__SIZEOF__POINTER == 8 // 64 bit machines
+  /* TODO: Add support for 32 bits */
+  return Error(ENOSYS);
----------------
labath wrote:

Make this a build-error instead. Or even better, implement the 32-bit version as well. It sounds like you just need to split the offset into two arguments, kind of like posix_fadvise does.

https://github.com/llvm/llvm-project/pull/222843