[libc-commits] [libc] [libc] add statvfs/fstatvfs (PR #86169)

[Nick Desaulniers via libc-commits]

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@@ -0,0 +1,85 @@
+//===-- Convert Statfs to Statvfs -------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_SYS_STATVFS_LINUX_STATFS_TO_STATVFS_H
+#define LLVM_LIBC_SRC_SYS_STATVFS_LINUX_STATFS_TO_STATVFS_H
+
+#include "llvm-libc-types/struct_statvfs.h"
+#include "src/__support/CPP/optional.h"
+#include "src/__support/OSUtil/syscall.h"
+#include "src/__support/macros/attributes.h"
+#include "src/errno/libc_errno.h"
+#include <asm/statfs.h>
+#include <sys/syscall.h>
+namespace LIBC_NAMESPACE {
+
+namespace statfs_utils {
+#ifdef SYS_statfs64
+using LinuxStatFs = statfs64;
+#else
+using LinuxStatFs = statfs;
+#endif
+
+LIBC_INLINE cpp::optional<LinuxStatFs> linux_statfs(const char *path) {
+#ifdef __clang__
+  // Disable pattern filling for result buffer: this struct is to be populated
+  // by the syscall.
+  [[clang::uninitialized]]
+#endif
+  LinuxStatFs result;
+  // On 32-bit platforms, original statfs cannot handle large file systems.
+  // In such cases, SYS_statfs64 is defined and should be used.
+#ifdef SYS_statfs64
+  int ret = syscall_impl<int>(SYS_statfs64, path, sizeof(result), &result);
+#else
+  int ret = syscall_impl<int>(SYS_statfs, path, &result);
+#endif
+  if (ret < 0) {
+    libc_errno = -ret;
+    return cpp::nullopt;
+  }
+  return result;
+}
+
+LIBC_INLINE cpp::optional<LinuxStatFs> linux_fstatfs(int fd) {
+  LinuxStatFs result;
+  // On 32-bit platforms, original fstatfs cannot handle large file systems.
+  // In such cases, SYS_fstatfs64 is defined and should be used.
+#ifdef SYS_fstatfs64
+  int ret = syscall_impl<int>(SYS_fstatfs64, fd, sizeof(result), &result);
+#else
+  int ret = syscall_impl<int>(SYS_fstatfs, fd, &result);
+#endif
+  if (ret < 0) {
+    libc_errno = -ret;
+    return cpp::nullopt;
+  }
+  return result;
+}
----------------
nickdesaulniers wrote:

bionic does something interesting.  It masks the value of result->f_flags with ~0x0020.

https://android.googlesource.com/platform/bionic/+/refs/heads/main/libc/bionic/sys_statfs.cpp#52 I wonder if this is necessary?

(bionic implements `statvfs`/`fstatvfs` in terms of calls to `statfs`/`fstatfs` which in turn call `statfs64`/`fstat64`).

https://github.com/llvm/llvm-project/pull/86169