[libc] Add implementation of functions stat, fstat and lstat.

[sivachandra]

Summary

All supporting type and macro definitions have also been added.

[lntue]

Is this error in the CI fixed with your latest revision yet?

In file included from /var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/stat.cpp:10:
/var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/kernel_statx.h:66:24: error: expected unqualified-id
constexpr unsigned int STATX_BASIC_STATS = 0x7FF;
                       ^
/usr/include/linux/stat.h:152:27: note: expanded from macro 'STATX_BASIC_STATS'
#define STATX_BASIC_STATS       0x000007ffU     /* The stuff in the normal stat struct */
                                ^
In file included from /var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/stat.cpp:10:
/var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/kernel_statx.h:76:55: error: expected unqualified-id
  long ret = syscall(SYS_statx, dirfd, path, flags, ::STATX_BASIC_STATS, &xbuf);
                                                      ^
/usr/include/linux/stat.h:152:27: note: expanded from macro 'STATX_BASIC_STATS'
#define STATX_BASIC_STATS       0x000007ffU     /* The stuff in the normal stat struct */
                                ^
2 errors generated.

[sivachandra]

Rename a mask to avoid conflict with name in linux headers.

[sivachandra]

In D134262#3803174, @lntue wrote:

Is this error in the CI fixed with your latest revision yet?

In file included from /var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/stat.cpp:10:
/var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/kernel_statx.h:66:24: error: expected unqualified-id
constexpr unsigned int STATX_BASIC_STATS = 0x7FF;
                       ^
/usr/include/linux/stat.h:152:27: note: expanded from macro 'STATX_BASIC_STATS'
#define STATX_BASIC_STATS       0x000007ffU     /* The stuff in the normal stat struct */
                                ^
In file included from /var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/stat.cpp:10:
/var/lib/buildkite-agent/builds/llvm-project/libc/src/sys/stat/linux/kernel_statx.h:76:55: error: expected unqualified-id
  long ret = syscall(SYS_statx, dirfd, path, flags, ::STATX_BASIC_STATS, &xbuf);
                                                      ^
/usr/include/linux/stat.h:152:27: note: expanded from macro 'STATX_BASIC_STATS'
#define STATX_BASIC_STATS       0x000007ffU     /* The stuff in the normal stat struct */
                                ^
2 errors generated.

This should be fixed now.

libc/config/linux/api.td

def UniStdAPI : PublicAPI<"unistd.h"> {
   let Types = ["off_t", "size_t", "ssize_t"];
 }
 
 def SysResourceAPI : PublicAPI<"sys/resource.h"> {
   let Types = ["rlim_t", "struct rlimit"];
 }
 
 def SysStatAPI : PublicAPI<"sys/stat.h"> {
-  let Types = ["mode_t"];
+  let Types = ["mode_t", "dev_t", "ino_t", "nlink_t", "uid_t", "gid_t", "off_t",
+               "struct timespec", "blksize_t", "blkcnt_t", "struct stat"];
 }
 
 def SysSendfileAPI : PublicAPI<"sys/sendfile.h"> {
   let Types = ["off_t", "size_t", "ssize_t"];
 }
 
 def SysUtsNameAPI : PublicAPI<"sys/utsname.h"> {
   let Types = ["struct utsname"];
 }

libc/config/linux/x86_64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
 
     # sys/sendfile entrypoints
     libc.src.sys.sendfile.sendfile
 
     # sys/stat.h entrypoints
     libc.src.sys.stat.chmod
     libc.src.sys.stat.fchmod
     libc.src.sys.stat.fchmodat
+    libc.src.sys.stat.fstat
+    libc.src.sys.stat.lstat
     libc.src.sys.stat.mkdir
     libc.src.sys.stat.mkdirat
+    libc.src.sys.stat.stat
 
     # sys/utsname.h entrypoints
     libc.src.sys.utsname.uname
 
     # unistd.h entrypoints
     libc.src.unistd.access
     libc.src.unistd.chdir
     libc.src.unistd.close

libc/include/CMakeLists.txt

 add_gen_header(
   sys_stat
   DEF_FILE sys/stat.h.def
   GEN_HDR sys/stat.h
   DEPENDS
     .llvm_libc_common_h
     .llvm-libc-macros.sys_stat_macros
     .llvm-libc-types.mode_t
+    .llvm-libc-types.struct_stat
 )
 
 add_gen_header(
   sys_sendfile
   DEF_FILE sys/sendfile.h.def
   GEN_HDR sys/sendfile.h
   DEPENDS
     .llvm_libc_common_h

libc/include/llvm-libc-macros/linux/fcntl-macros.h

 #define S_IXGRP 010
 #define S_IRWXO 07
 #define S_IROTH 04
 #define S_IWOTH 02
 #define S_IXOTH 01
 #define S_ISUID 04000
 #define S_ISGID 02000
 
+// File type flags
+#define S_IFMT 0170000
+#define S_IFDIR 0040000
+#define S_IFCHR 0020000
+#define S_IFBLK 0060000
+#define S_IFREG 0100000
+#define S_FIFO 0010000
+#define S_IFLNK 0120000
+
 // Special directory FD to indicate that the path argument to
 // openat is relative to the current directory.
 #define AT_FDCWD -100
 
 // Special flag to the function unlinkat to indicate that it
 // has to perform the equivalent of "rmdir" on the path argument.
 #define AT_REMOVEDIR 0x200
 
+// Special flag for functions like lstat to convey that symlinks
+// should not be followed.
+#define AT_SYMLINK_NOFOLLOW 0x100
+
+// Allow empty relative pathname.
+#define AT_EMPTY_PATH 0x1000
+
 // Values of SYS_fcntl commands.
 #define F_DUPFD 0
 #define F_GETFD 1
 #define F_SETFD 2
 #define F_GETFL 3
 #define F_SETFL 4
 
 #endif // __LLVM_LIBC_MACROS_LINUX_FCNTL_MACROS_H

libc/include/llvm-libc-types/CMakeLists.txt

 add_header(off64_t HDR off64_t.h)
 add_header(size_t HDR size_t.h)
 add_header(__bsearchcompare_t HDR __bsearchcompare_t.h)
 add_header(__call_once_func_t HDR __call_once_func_t.h)
 add_header(__futex_word HDR __futex_word.h)
 add_header(__mutex_type HDR __mutex_type.h DEPENDS .__futex_word)
 add_header(__pthread_start_t HDR __pthread_start_t.h)
 add_header(__pthread_tss_dtor_t HDR __pthread_tss_dtor_t.h)
 add_header(__qsortcompare_t HDR __qsortcompare_t.h)
 add_header(__sighandler_t HDR __sighandler_t.h)
 add_header(__thread_type HDR __thread_type.h)
+add_header(blkcnt_t HDR blkcnt_t.h)
+add_header(blksize_t HDR blksize_t.h)
 add_header(cnd_t HDR cnd_t.h)
 add_header(cookie_io_functions_t HDR cookie_io_functions_t.h DEPENDS .off64_t)
 add_header(double_t HDR double_t.h)
 add_header(DIR HDR DIR.h)
+add_header(dev_t HDR dev_t.h)
 add_header(div_t HDR div_t.h)
 add_header(ldiv_t HDR ldiv_t.h)
 add_header(lldiv_t HDR lldiv_t.h)
 add_header(FILE HDR FILE.h)
 add_header(fenv_t HDR fenv_t.h)
 add_header(fexcept_t HDR fexcept_t.h)
 add_header(float_t HDR float_t.h)
+add_header(gid_t HDR gid_t.h)
+add_header(uid_t HDR uid_t.h)
 add_header(imaxdiv_t HDR imaxdiv_t.h)
 add_header(ino_t HDR ino_t.h)
 add_header(mode_t HDR mode_t.h)
 add_header(mtx_t HDR mtx_t.h DEPENDS .__futex_word .__mutex_type)
+add_header(nlink_t HDR nlink_t.h)
 add_header(off_t HDR off_t.h)
 add_header(once_flag HDR once_flag.h DEPENDS .__futex_word)
 add_header(pthread_attr_t HDR pthread_attr_t.h DEPENDS .size_t)
 add_header(pthread_key_t HDR pthread_key_t.h)
 add_header(pthread_mutex_t HDR pthread_mutex_t.h DEPENDS .__futex_word .__mutex_type)
 add_header(pthread_t HDR pthread_t.h DEPENDS .__thread_type)
 add_header(pthread_mutexattr_t HDR pthread_mutexattr_t.h)
 add_header(rlim_t HDR rlim_t.h)
 add_header(struct_rlimit HDR struct_rlimit.h DEPENDS .rlim_t)
 add_header(ssize_t HDR ssize_t.h)
 add_header(struct_dirent HDR struct_dirent.h DEPENDS .ino_t .off_t)
 add_header(struct_sigaction HDR struct_sigaction.h)
+add_header(time_t HDR time_t.h)
+add_header(struct_timespec HDR struct_timespec.h DEPENDS .time_t)
+add_header(
+  struct_stat
+  HDR struct_stat.h
+  DEPENDS
+    .dev_t .ino_t .mode_t .nlink_t .uid_t .gid_t .off_t .struct_timespec
+    .blksize_t .blkcnt_t
+)
 add_header(struct_tm HDR struct_tm.h)
 add_header(struct_utsname HDR struct_utsname.h)
 add_header(thrd_start_t HDR thrd_start_t.h)
 add_header(thrd_t HDR thrd_t.h DEPENDS .__thread_type)
-add_header(time_t HDR time_t.h)
 add_header(tss_t HDR tss_t.h)
 add_header(tss_dtor_t HDR tss_dtor_t.h)
 add_header(__atexithandler_t HDR __atexithandler_t.h)

libc/include/llvm-libc-types/blkcnt_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of blkcnt_t type ---------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_BLKCNT_T_H__
+#define __LLVM_LIBC_TYPES_BLKCNT_T_H__
 
-typedef unsigned long ino_t;
+typedef __INTPTR_TYPE__ blkcnt_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_BLKCNT_T_H__

libc/include/llvm-libc-types/blksize_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of blksize_t type --------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_BLKSIZE_T_H__
+#define __LLVM_LIBC_TYPES_BLKSIZE_T_H__
 
-typedef unsigned long ino_t;
+typedef __INTPTR_TYPE__ blksize_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_BLKSIZE_T_H__

libc/include/llvm-libc-types/dev_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of dev_t type ------------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_DEV_T_H__
+#define __LLVM_LIBC_TYPES_DEV_T_H__
 
-typedef unsigned long ino_t;
+typedef __UINT64_TYPE__ dev_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_DEV_T_H__

libc/include/llvm-libc-types/gid_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of gid_t type ------------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_GID_T_H__
+#define __LLVM_LIBC_TYPES_GID_T_H__
 
-typedef unsigned long ino_t;
+typedef __UINT32_TYPE__ gid_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_GID_T_H__

libc/include/llvm-libc-types/ino_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of ino_t type ------------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
 #define __LLVM_LIBC_TYPES_INO_T_H__
 
-typedef unsigned long ino_t;
+typedef __UINTPTR_TYPE__ ino_t;
 
 #endif // __LLVM_LIBC_TYPES_INO_T_H__

libc/include/llvm-libc-types/nlink_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of nlink_t type ----------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_NLINK_T_H__
+#define __LLVM_LIBC_TYPES_NLINK_T_H__
 
-typedef unsigned long ino_t;
+typedef __UINTPTR_TYPE__ nlink_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_NLINK_T_H__

libc/include/llvm-libc-types/struct_stat.h

+//===-- Definition of struct stat -----------------------------------------===//
+//
+// 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_TYPES_STRUCT_STAT_H__
+#define __LLVM_LIBC_TYPES_STRUCT_STAT_H__
+
+#include <llvm-libc-types/blkcnt_t.h>
+#include <llvm-libc-types/blksize_t.h>
+#include <llvm-libc-types/dev_t.h>
+#include <llvm-libc-types/gid_t.h>
+#include <llvm-libc-types/ino_t.h>
+#include <llvm-libc-types/mode_t.h>
+#include <llvm-libc-types/nlink_t.h>
+#include <llvm-libc-types/off_t.h>
+#include <llvm-libc-types/struct_timespec.h>
+#include <llvm-libc-types/uid_t.h>
+
+struct stat {
+  dev_t st_dev;
+  ino_t st_ino;
+  mode_t st_mode;
+  nlink_t st_nlink;
+  uid_t st_uid;
+  gid_t st_gid;
+  dev_t st_rdev;
+  off_t st_size;
+  struct timespec st_atim;
+  struct timespec st_mtim;
+  struct timespec st_ctim;
+  blksize_t st_blksize;
+  blkcnt_t st_blocks;
+};
+
+#endif // __LLVM_LIBC_TYPES_STRUCT_STAT_H__

libc/include/llvm-libc-types/struct_timespec.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of struct timespec -------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_TIMESPEC_H__
+#define __LLVM_LIBC_TYPES_TIMESPEC_H__
 
-typedef unsigned long ino_t;
+#include <llvm-libc-types/time_t.h>
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+struct timespec {
+  time_t tv_sec;
+  long tv_nsec;
+};
+
+#endif // __LLVM_LIBC_TYPES_TIMESPEC_H__

libc/include/llvm-libc-types/time_t.h

 //===-- Definition of the type time_t -------------------------------------===//
 //
 // 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_TYPES_TIME_T_H__
 #define __LLVM_LIBC_TYPES_TIME_T_H__
 
-typedef long time_t;
+typedef __INTPTR_TYPE__ time_t;
 
 #endif // __LLVM_LIBC_TYPES_TIME_T_H__

libc/include/llvm-libc-types/uid_t.h

-//===-- Definition of type ino_t ------------------------------------------===//
+//===-- Definition of uid_t type ------------------------------------------===//
 //
 // 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_TYPES_INO_T_H__
-#define __LLVM_LIBC_TYPES_INO_T_H__
+#ifndef __LLVM_LIBC_TYPES_UID_T_H__
+#define __LLVM_LIBC_TYPES_UID_T_H__
 
-typedef unsigned long ino_t;
+typedef __UINT32_TYPE__ uid_t;
 
-#endif // __LLVM_LIBC_TYPES_INO_T_H__
+#endif // __LLVM_LIBC_TYPES_UID_T_H__

libc/spec/posix.td

 def ConstRestrictedStructSigactionPtr : ConstType<RestrictedStructSigactionPtr>;
 
 def PThreadStartT : NamedType<"__pthread_start_t">;
 def PThreadTSSDtorT : NamedType<"__pthread_tss_dtor_t">;
 def PThreadKeyT : NamedType<"pthread_key_t">;
 def PThreadKeyTPtr : PtrType<PThreadKeyT>;
 
 def InoT : NamedType<"ino_t">;
+def UidT : NamedType<"uid_t">;
+def GidT : NamedType<"gid_t">;
+def DevT : NamedType<"dev_t">;
+def BlkSizeT : NamedType<"blksize_t">;
+def BlkCntT : NamedType<"blkcnt_t">;
+def NLinkT : NamedType<"nlink_t">;
+def TimeSpec : NamedType<"struct timespec">;
+
+def StatType : NamedType<"struct stat">;
+def StatTypePtr : PtrType<StatType>;
+def RestrictedStatTypePtr : RestrictedPtrType<StatType>;
+
 def DIR : NamedType<"DIR">;
 def DIRPtr : PtrType<DIR>;
 def DIRRestrictedPtr : RestrictedPtrType<DIR>;
 def StructDirent : NamedType<"struct dirent">;
 def StructDirentPtr : PtrType<StructDirent>;
 def StructDirentPtrPtr : PtrType<StructDirentPtr>;
 def ConstStructDirentPtrPtr : ConstType<StructDirentPtrPtr>;
 
[
           [ArgSpec<ConstStructRLimitPtr>]
         >,
     ]
   >;
 
   HeaderSpec SysStat = HeaderSpec<
     "sys/stat.h",
     [], // Macros
-    [ModeTType], // Types
+    [ModeTType, DevT, InoT, UidT, GidT, TimeSpec, BlkSizeT, BlkCntT, OffTType, NLinkT, StatType], // Types
     [], // Enumerations
     [
         FunctionSpec<
           "chmod",
           RetValSpec<IntType>,
           [ArgSpec<ConstCharPtr>, ArgSpec<ModeTType>]
         >,
         FunctionSpec<
           "fchmod",
           RetValSpec<IntType>,
           [ArgSpec<IntType>, ArgSpec<ModeTType>]
         >,
         FunctionSpec<
           "fchmodat",
           RetValSpec<IntType>,
           [ArgSpec<IntType>, ArgSpec<ConstCharPtr>, ArgSpec<ModeTType>, ArgSpec<IntType>]
         >,
         FunctionSpec<
+            "fstat",
+            RetValSpec<IntType>,
+            [ArgSpec<IntType>, ArgSpec<StatTypePtr>]
+        >,
+        FunctionSpec<
+            "lstat",
+            RetValSpec<IntType>,
+            [ArgSpec<ConstRestrictedCharPtr>, ArgSpec<RestrictedStatTypePtr>]
+        >,
+        FunctionSpec<
             "mkdir",
             RetValSpec<IntType>,
             [ArgSpec<ConstCharPtr>, ArgSpec<ModeTType>]
         >,
         FunctionSpec<
             "mkdirat",
             RetValSpec<IntType>,
             [ArgSpec<IntType>, ArgSpec<ConstCharPtr>, ArgSpec<ModeTType>]
         >,
+        FunctionSpec<
+            "stat",
+            RetValSpec<IntType>,
+            [ArgSpec<ConstRestrictedCharPtr>, ArgSpec<RestrictedStatTypePtr>]
+        >,
     ]
   >;
 
   NamedType StructUtsName = NamedType<"struct utsname">;
   PtrType StructUtsNamePtr = PtrType<StructUtsName>;
   HeaderSpec SysUtsName = HeaderSpec<
     "sys/utsname.h",
     [], // Macros

libc/src/sys/stat/CMakeLists.txt

 add_entrypoint_object(
   fchmod
   ALIAS
   DEPENDS
     .${LIBC_TARGET_OS}.fchmod
 )
 
 add_entrypoint_object(
+  fstat
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.fstat
+)
+
+add_entrypoint_object(
+  lstat
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.lstat
+)
+
+add_entrypoint_object(
   mkdir
   ALIAS
   DEPENDS
     .${LIBC_TARGET_OS}.mkdir
 )
 
 add_entrypoint_object(
   mkdirat
   ALIAS
   DEPENDS
     .${LIBC_TARGET_OS}.mkdirat
 )
+
+add_entrypoint_object(
+  stat
+  ALIAS
+  DEPENDS
+    .${LIBC_TARGET_OS}.stat
+)

libc/src/sys/stat/fstat.h

+//===-- Implementation header for fstat -------------------------*- 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_STAT_FSTAT_H
+#define LLVM_LIBC_SRC_SYS_STAT_FSTAT_H
+
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+int fstat(int fd, struct stat *statbuf);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SYS_STAT_FSTAT_H

libc/src/sys/stat/linux/CMakeLists.txt

add_entrypoint_object(
   HDRS
     ../mkdirat.h
   DEPENDS
     libc.include.sys_stat
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
     libc.src.errno.errno
 )
+
+add_header_library(
+  kernel_statx
+  HDRS
+    kernel_statx.h
+  DEPENDS
+    libc.include.sys_stat
+    libc.include.sys_syscall
+    libc.src.__support.OSUtil.osutil
+    libc.src.errno.errno
+)
+
+add_entrypoint_object(
+  stat
+  SRCS
+    stat.cpp
+  HDRS
+    ../stat.h
+  DEPENDS
+    .kernel_statx
+    libc.include.fcntl
+    libc.include.sys_stat
+)
+
+add_entrypoint_object(
+  lstat
+  SRCS
+    lstat.cpp
+  HDRS
+    ../lstat.h
+  DEPENDS
+    .kernel_statx
+    libc.include.fcntl
+    libc.include.sys_stat
+)
+
+add_entrypoint_object(
+  fstat
+  SRCS
+    fstat.cpp
+  HDRS
+    ../fstat.h
+  DEPENDS
+    .kernel_statx
+    libc.include.fcntl
+    libc.include.sys_stat
+)

libc/src/sys/stat/linux/fstat.cpp

+//===-- Linux implementation of fstat -------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/stat/fstat.h"
+#include "kernel_statx.h"
+
+#include "src/__support/common.h"
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, fstat, (int fd, struct stat *statbuf)) {
+  return statx(fd, "", AT_EMPTY_PATH, statbuf);
+}
+
+} // namespace __llvm_libc

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

+//===-- Wrapper over SYS_statx syscall ------------------------------------===//
+//
+// 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_STAT_LINUX_STATX_H
+#define LLVM_LIBC_SRC_SYS_STAT_LINUX_STATX_H
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+
+#include <errno.h>
+#include <stdint.h>
+#include <sys/stat.h>
+#include <sys/syscall.h> // For syscall numbers.
+
+// It is safe to include this kernel header as it is designed to be
+// included from user programs without causing any name pollution.
+#include <linux/kdev_t.h>
+
+namespace {
+
+// The type definitions in the internal namespace match kernel's definition of
+// the statx_timestamp and statx types in linux/stat.h. We define equivalent
+// types here instead of including that header file to avoid name mixup between
+// linux/stat.h and the libc's stat.h.
+struct statx_timestamp {
+  int64_t tv_sec;
+  uint32_t tv_nsec;
+  int32_t __reserved;
+};
+
+struct statx_buf {
+  uint32_t stx_mask;       // What results were written
+  uint32_t stx_blksize;    // Preferred general I/O size
+  uint64_t stx_attributes; // Flags conveying information about the file
+  uint32_t stx_nlink;      // Number of hard links
+  uint32_t stx_uid;        // User ID of owner
+  uint32_t stx_gid;        // Group ID of owner
+  uint16_t stx_mode;       // File mode
+  uint16_t __spare0[1];
+  uint64_t stx_ino;                 // Inode number
+  uint64_t stx_size;                // File size
+  uint64_t stx_blocks;              // Number of 512-byte blocks allocated
+  uint64_t stx_attributes_mask;     // Mask to show what's supported in
+                                    // stx_attributes
+  struct statx_timestamp stx_atime; // Last access time
+  struct statx_timestamp stx_btime; // File creation time
+  struct statx_timestamp stx_ctime; // Last attribute change time
+  struct statx_timestamp stx_mtime; // Last data modification time
+  uint32_t stx_rdev_major;          // Device ID of special file
+  uint32_t stx_rdev_minor;
+  uint32_t stx_dev_major; // ID of device containing file
+  uint32_t stx_dev_minor;
+  uint64_t stx_mnt_id;
+  uint64_t __spare2;
+  uint64_t __spare3[12]; // Spare space for future expansion
+};
+
+// The below mask value is based on the definition of a similarly
+// named macro in linux/stat.h. When this flag is passed for the
+// mask argument to the statx syscall, all fields except the
+// stx_btime field will be filled in.
+constexpr unsigned int STATX_BASIC_STATS_MASK = 0x7FF;
+
+} // Anonymous namespace
+
+namespace __llvm_libc {
+
+inline int statx(int dirfd, const char *__restrict path, int flags,
+                 struct stat *__restrict statbuf) {
+  // We make a statx syscall and copy out the result into the |statbuf|.
+  ::statx_buf xbuf;
+  long ret =
+      syscall(SYS_statx, dirfd, path, flags, ::STATX_BASIC_STATS_MASK, &xbuf);
+  if (ret < 0) {
+    errno = -ret;
+    return -1;
+  }
+
+  statbuf->st_dev = MKDEV(xbuf.stx_dev_major, xbuf.stx_dev_minor);
+  statbuf->st_ino = xbuf.stx_ino;
+  statbuf->st_mode = xbuf.stx_mode;
+  statbuf->st_nlink = xbuf.stx_nlink;
+  statbuf->st_uid = xbuf.stx_uid;
+  statbuf->st_gid = xbuf.stx_gid;
+  statbuf->st_rdev = MKDEV(xbuf.stx_rdev_major, xbuf.stx_rdev_minor);
+  statbuf->st_size = xbuf.stx_size;
+  statbuf->st_atim.tv_sec = xbuf.stx_atime.tv_sec;
+  statbuf->st_atim.tv_nsec = xbuf.stx_atime.tv_nsec;
+  statbuf->st_mtim.tv_sec = xbuf.stx_mtime.tv_sec;
+  statbuf->st_mtim.tv_nsec = xbuf.stx_mtime.tv_nsec;
+  statbuf->st_ctim.tv_sec = xbuf.stx_ctime.tv_sec;
+  statbuf->st_ctim.tv_nsec = xbuf.stx_ctime.tv_nsec;
+  statbuf->st_blksize = xbuf.stx_blksize;
+  statbuf->st_blocks = xbuf.stx_blocks;
+
+  return 0;
+}
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SYS_STAT_LINUX_STATX_H

libc/src/sys/stat/linux/lstat.cpp

+//===-- Linux implementation of lstat -------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/stat/lstat.h"
+#include "kernel_statx.h"
+
+#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
+#include "src/__support/common.h"
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, lstat,
+                   (const char *__restrict path,
+                    struct stat *__restrict statbuf)) {
+  return statx(AT_FDCWD, path, AT_SYMLINK_NOFOLLOW, statbuf);
+}
+
+} // namespace __llvm_libc

libc/src/sys/stat/linux/stat.cpp

+//===-- Linux implementation of stat --------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/sys/stat/stat.h"
+#include "kernel_statx.h"
+
+#include "src/__support/common.h"
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(int, stat,
+                   (const char *__restrict path,
+                    struct stat *__restrict statbuf)) {
+  return statx(AT_FDCWD, path, 0, statbuf);
+}
+
+} // namespace __llvm_libc

libc/src/sys/stat/lstat.h

+//===-- Implementation header for lstat -------------------------*- 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_STAT_LSTAT_H
+#define LLVM_LIBC_SRC_SYS_STAT_LSTAT_H
+
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+int lstat(const char *__restrict path, struct stat *__restrict statbuf);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SYS_STAT_LSTAT_H

libc/src/sys/stat/stat.h

+//===-- Implementation header for stat --------------------------*- 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_STAT_STAT_H
+#define LLVM_LIBC_SRC_SYS_STAT_STAT_H
+
+#include <sys/stat.h>
+
+namespace __llvm_libc {
+
+int stat(const char *__restrict path, struct stat *__restrict statbuf);
+
+} // namespace __llvm_libc
+
+#endif // LLVM_LIBC_SRC_SYS_STAT_STAT_H

libc/test/src/sys/stat/CMakeLists.txt

SRCS
     mkdirat_test.cpp
   DEPENDS
     libc.include.errno
     libc.include.fcntl
     libc.include.sys_stat
     libc.src.sys.stat.mkdirat
     libc.src.unistd.rmdir
 )
+
+add_libc_unittest(
+  stat_test
+  SUITE
+    libc_sys_stat_unittests
+  SRCS
+    stat_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.fcntl
+    libc.include.sys_stat
+    libc.src.sys.stat.stat
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.unlink
+)
+
+add_libc_unittest(
+  lstat_test
+  SUITE
+    libc_sys_stat_unittests
+  SRCS
+    lstat_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.fcntl
+    libc.include.sys_stat
+    libc.src.sys.stat.lstat
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.unlink
+)
+
+add_libc_unittest(
+  fstat_test
+  SUITE
+    libc_sys_stat_unittests
+  SRCS
+    fstat_test.cpp
+  DEPENDS
+    libc.include.errno
+    libc.include.fcntl
+    libc.include.sys_stat
+    libc.src.sys.stat.fstat
+    libc.src.fcntl.open
+    libc.src.unistd.close
+    libc.src.unistd.unlink
+)

libc/test/src/sys/stat/fstat_test.cpp

+//===-- Unittests for fstat -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/fcntl/open.h"
+#include "src/sys/stat/fstat.h"
+#include "src/unistd/close.h"
+#include "src/unistd/unlink.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+TEST(LlvmLibcFStatTest, CreatAndReadMode) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+
+  // The test file is initially writable. We open it for writing and ensure
+  // that it indeed can be opened for writing. Next, we close the file and
+  // make it readonly using chmod. We test that chmod actually succeeded by
+  // trying to open the file for writing and failing.
+  constexpr const char *TEST_FILE = "testdata/fstat.test";
+  errno = 0;
+
+  int fd = __llvm_libc::open(TEST_FILE, O_CREAT | O_WRONLY, S_IRWXU);
+  ASSERT_GT(fd, 0);
+  ASSERT_EQ(errno, 0);
+
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::fstat(fd, &statbuf), Succeeds(0));
+
+  ASSERT_EQ(int(statbuf.st_mode), int(S_IRWXU | S_IFREG));
+
+  ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcFStatTest, NonExistentFile) {
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::fstat(-1, &statbuf), Fails(EBADF));
+  errno = 0;
+}

libc/test/src/sys/stat/lstat_test.cpp

+//===-- Unittests for lstat -----------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/fcntl/open.h"
+#include "src/sys/stat/lstat.h"
+#include "src/unistd/close.h"
+#include "src/unistd/unlink.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+TEST(LlvmLibcLStatTest, CreatAndReadMode) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+
+  // The test file is initially writable. We open it for writing and ensure
+  // that it indeed can be opened for writing. Next, we close the file and
+  // make it readonly using chmod. We test that chmod actually succeeded by
+  // trying to open the file for writing and failing.
+  constexpr const char *TEST_FILE = "testdata/lstat.test";
+  errno = 0;
+
+  int fd = __llvm_libc::open(TEST_FILE, O_CREAT | O_WRONLY, S_IRWXU);
+  ASSERT_GT(fd, 0);
+  ASSERT_EQ(errno, 0);
+  ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::lstat(TEST_FILE, &statbuf), Succeeds(0));
+
+  ASSERT_EQ(int(statbuf.st_mode), int(S_IRWXU | S_IFREG));
+
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcLStatTest, NonExistentFile) {
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::lstat("non-existent-file", &statbuf), Fails(ENOENT));
+  errno = 0;
+}

libc/test/src/sys/stat/stat_test.cpp

+//===-- Unittests for stat ------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/fcntl/open.h"
+#include "src/sys/stat/stat.h"
+#include "src/unistd/close.h"
+#include "src/unistd/unlink.h"
+#include "test/ErrnoSetterMatcher.h"
+#include "utils/UnitTest/Test.h"
+#include "utils/testutils/FDReader.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+
+TEST(LlvmLibcStatTest, CreatAndReadMode) {
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Succeeds;
+
+  // The test file is initially writable. We open it for writing and ensure
+  // that it indeed can be opened for writing. Next, we close the file and
+  // make it readonly using chmod. We test that chmod actually succeeded by
+  // trying to open the file for writing and failing.
+  constexpr const char *TEST_FILE = "testdata/stat.test";
+  errno = 0;
+
+  int fd = __llvm_libc::open(TEST_FILE, O_CREAT | O_WRONLY, S_IRWXU);
+  ASSERT_GT(fd, 0);
+  ASSERT_EQ(errno, 0);
+  ASSERT_THAT(__llvm_libc::close(fd), Succeeds(0));
+
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::stat(TEST_FILE, &statbuf), Succeeds(0));
+
+  ASSERT_EQ(int(statbuf.st_mode), int(S_IRWXU | S_IFREG));
+
+  ASSERT_THAT(__llvm_libc::unlink(TEST_FILE), Succeeds(0));
+}
+
+TEST(LlvmLibcStatTest, NonExistentFile) {
+  errno = 0;
+  using __llvm_libc::testing::ErrnoSetterMatcher::Fails;
+  struct stat statbuf;
+  ASSERT_THAT(__llvm_libc::stat("non-existent-file", &statbuf), Fails(ENOENT));
+  errno = 0;
+}