libc/src/sys/stat/linux/kernel_statx.h

   1 //===-- Wrapper over SYS_statx syscall ------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIBC_SRC_SYS_STAT_LINUX_KERNEL_STATX_H
  10 #define LLVM_LIBC_SRC_SYS_STAT_LINUX_KERNEL_STATX_H
  11
  12 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  13 #include "src/__support/common.h"
  14 #include "src/__support/macros/config.h"
  15
  16 #include <stdint.h>
  17 #include <sys/stat.h>
  18 #include <sys/syscall.h> // For syscall numbers.
  19
  20 // It is safe to include this kernel header as it is designed to be
  21 // included from user programs without causing any name pollution.
  22 #include <linux/kdev_t.h>
  23
  24 namespace {
  25
  26 // The type definitions in the internal namespace match kernel's definition of
  27 // the statx_timestamp and statx types in linux/stat.h. We define equivalent
  28 // types here instead of including that header file to avoid name mixup between
  29 // linux/stat.h and the libc's stat.h.
  30 struct statx_timestamp {
  31   int64_t tv_sec;
  32   uint32_t tv_nsec;
  33   int32_t __reserved;
  34 };
  35
  36 struct statx_buf {
  37   uint32_t stx_mask;       // What results were written
  38   uint32_t stx_blksize;    // Preferred general I/O size
  39   uint64_t stx_attributes; // Flags conveying information about the file
  40   uint32_t stx_nlink;      // Number of hard links
  41   uint32_t stx_uid;        // User ID of owner
  42   uint32_t stx_gid;        // Group ID of owner
  43   uint16_t stx_mode;       // File mode
  44   uint16_t __spare0[1];
  45   uint64_t stx_ino;                 // Inode number
  46   uint64_t stx_size;                // File size
  47   uint64_t stx_blocks;              // Number of 512-byte blocks allocated
  48   uint64_t stx_attributes_mask;     // Mask to show what's supported in
  49                                     // stx_attributes
  50   struct statx_timestamp stx_atime; // Last access time
  51   struct statx_timestamp stx_btime; // File creation time
  52   struct statx_timestamp stx_ctime; // Last attribute change time
  53   struct statx_timestamp stx_mtime; // Last data modification time
  54   uint32_t stx_rdev_major;          // Device ID of special file
  55   uint32_t stx_rdev_minor;
  56   uint32_t stx_dev_major; // ID of device containing file
  57   uint32_t stx_dev_minor;
  58   uint64_t stx_mnt_id;
  59   uint64_t __spare2;
  60   uint64_t __spare3[12]; // Spare space for future expansion
  61 };
  62
  63 // The below mask value is based on the definition of a similarly
  64 // named macro in linux/stat.h. When this flag is passed for the
  65 // mask argument to the statx syscall, all fields except the
  66 // stx_btime field will be filled in.
  67 constexpr unsigned int STATX_BASIC_STATS_MASK = 0x7FF;
  68
  69 } // Anonymous namespace
  70
  71 namespace LIBC_NAMESPACE_DECL {
  72
  73 LIBC_INLINE int statx(int dirfd, const char *__restrict path, int flags,
  74                       struct stat *__restrict statbuf) {
  75   // We make a statx syscall and copy out the result into the |statbuf|.
  76   ::statx_buf xbuf;
  77   int ret = LIBC_NAMESPACE::syscall_impl<int>(SYS_statx, dirfd, path, flags,
  78                                               ::STATX_BASIC_STATS_MASK, &xbuf);
  79   if (ret < 0)
  80     return -ret;
  81
  82   statbuf->st_dev = MKDEV(xbuf.stx_dev_major, xbuf.stx_dev_minor);
  83   statbuf->st_ino = static_cast<decltype(statbuf->st_ino)>(xbuf.stx_ino);
  84   statbuf->st_mode = xbuf.stx_mode;
  85   statbuf->st_nlink = xbuf.stx_nlink;
  86   statbuf->st_uid = xbuf.stx_uid;
  87   statbuf->st_gid = xbuf.stx_gid;
  88   statbuf->st_rdev = MKDEV(xbuf.stx_rdev_major, xbuf.stx_rdev_minor);
  89   statbuf->st_size = xbuf.stx_size;
  90   statbuf->st_atim.tv_sec = xbuf.stx_atime.tv_sec;
  91   statbuf->st_atim.tv_nsec = xbuf.stx_atime.tv_nsec;
  92   statbuf->st_mtim.tv_sec = xbuf.stx_mtime.tv_sec;
  93   statbuf->st_mtim.tv_nsec = xbuf.stx_mtime.tv_nsec;
  94   statbuf->st_ctim.tv_sec = xbuf.stx_ctime.tv_sec;
  95   statbuf->st_ctim.tv_nsec = xbuf.stx_ctime.tv_nsec;
  96   statbuf->st_blksize = xbuf.stx_blksize;
  97   statbuf->st_blocks =
  98       static_cast<decltype(statbuf->st_blocks)>(xbuf.stx_blocks);
  99
 100   return 0;
 101 }
 102
 103 } // namespace LIBC_NAMESPACE_DECL
 104
 105 #endif // LLVM_LIBC_SRC_SYS_STAT_LINUX_KERNEL_STATX_H