//===- llvm/Support/Unix/Path.inc - Unix Path Implementation ----*- 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

//

//===----------------------------------------------------------------------===//

//

// This file implements the Unix specific implementation of the Path API.

//

//===----------------------------------------------------------------------===//

//===----------------------------------------------------------------------===//

//=== WARNING: Implementation here must contain only generic UNIX code that

//===          is guaranteed to work on *all* UNIX variants.

//===----------------------------------------------------------------------===//

#include "Unix.h"

#include <limits.h>

#include <stdio.h>

#if HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif

#if HAVE_FCNTL_H

#include <fcntl.h>

#endif

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef HAVE_SYS_MMAN_H

#include <sys/mman.h>

#endif

#include <dirent.h>

#include <pwd.h>

#ifdef __APPLE__

#include <mach-o/dyld.h>

#include <sys/attr.h>

#include <copyfile.h>

#elif defined(__FreeBSD__)

#include <osreldate.h>

#if __FreeBSD_version >= 1300057

#include <sys/auxv.h>

#else

#include <machine/elf.h>

extern char **environ;

#endif

#elif defined(__DragonFly__)

#include <sys/mount.h>

#endif

// Both stdio.h and cstdio are included via different paths and

// stdcxx's cstdio doesn't include stdio.h, so it doesn't #undef the macros

// either.

#undef ferror

#undef feof

// For GNU Hurd

#if defined(__GNU__) && !defined(PATH_MAX)

# define PATH_MAX 4096

#endif

#include <sys/types.h>

#if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(__FreeBSD__) &&   \

    !defined(__linux__) && !defined(__FreeBSD_kernel__) && !defined(_AIX)

#include <sys/statvfs.h>

#define STATVFS statvfs

#define FSTATVFS fstatvfs

#define STATVFS_F_FRSIZE(vfs) vfs.f_frsize

#else

#if defined(__OpenBSD__) || defined(__FreeBSD__)

#include <sys/mount.h>

#include <sys/param.h>

#elif defined(__linux__)

#if defined(HAVE_LINUX_MAGIC_H)

#include <linux/magic.h>

#else

#if defined(HAVE_LINUX_NFS_FS_H)

#include <linux/nfs_fs.h>

#endif

#if defined(HAVE_LINUX_SMB_H)

#include <linux/smb.h>

#endif

#endif

#include <sys/vfs.h>

#elif defined(_AIX)

#include <sys/statfs.h>

// <sys/vmount.h> depends on `uint` to be a typedef from <sys/types.h> to

// `uint_t`; however, <sys/types.h> does not always declare `uint`. We provide

// the typedef prior to including <sys/vmount.h> to work around this issue.

typedef uint_t uint;

#include <sys/vmount.h>

#else

#include <sys/mount.h>

#endif

#define STATVFS statfs

#define FSTATVFS fstatfs

#define STATVFS_F_FRSIZE(vfs) static_cast<uint64_t>(vfs.f_bsize)

#endif

#if defined(__NetBSD__) || defined(__DragonFly__) || defined(__GNU__)

#define STATVFS_F_FLAG(vfs) (vfs).f_flag

#else

#define STATVFS_F_FLAG(vfs) (vfs).f_flags

#endif

using namespace llvm;

namespace llvm {

namespace sys  {

namespace fs {

const file_t kInvalidFile = -1;

#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) ||     \

    defined(__minix) || defined(__FreeBSD_kernel__) || defined(__linux__) ||   \

    defined(__CYGWIN__) || defined(__DragonFly__) || defined(_AIX) || defined(__GNU__)

static int

test_dir(char ret[PATH_MAX], const char *dir, const char *bin)

{

  struct stat sb;

  char fullpath[PATH_MAX];

  int chars = snprintf(fullpath, PATH_MAX, "%s/%s", dir, bin);

  // We cannot write PATH_MAX characters because the string will be terminated

  // with a null character. Fail if truncation happened.

  if (chars >= PATH_MAX)

    return 1;

  if (!realpath(fullpath, ret))

    return 1;

  if (stat(fullpath, &sb) != 0)

    return 1;

  return 0;

}

static char *

getprogpath(char ret[PATH_MAX], const char *bin)

{

  /* First approach: absolute path. */

  if (bin[0] == '/') {

    if (test_dir(ret, "/", bin) == 0)

      return ret;

    return nullptr;

  }

  /* Second approach: relative path. */

  if (strchr(bin, '/')) {

    char cwd[PATH_MAX];

    if (!getcwd(cwd, PATH_MAX))

      return nullptr;

    if (test_dir(ret, cwd, bin) == 0)

      return ret;

    return nullptr;

  }

  /* Third approach: $PATH */

  char *pv;

  if ((pv = getenv("PATH")) == nullptr)

    return nullptr;

  char *s = strdup(pv);

  if (!s)

    return nullptr;

  char *state;

  for (char *t = strtok_r(s, ":", &state); t != nullptr;

       t = strtok_r(nullptr, ":", &state)) {

    if (test_dir(ret, t, bin) == 0) {

      free(s);

      return ret;

    }

  }

  free(s);

  return nullptr;

}

#endif // __FreeBSD__ || __NetBSD__ || __FreeBSD_kernel__

/// GetMainExecutable - Return the path to the main executable, given the

/// value of argv[0] from program startup.

std::string getMainExecutable(const char *argv0, void *MainAddr) {

#if defined(__APPLE__)

  // On OS X the executable path is saved to the stack by dyld. Reading it

  // from there is much faster than calling dladdr, especially for large

  // binaries with symbols.

  char exe_path[PATH_MAX];

  uint32_t size = sizeof(exe_path);

  if (_NSGetExecutablePath(exe_path, &size) == 0) {

    char link_path[PATH_MAX];

    if (realpath(exe_path, link_path))

      return link_path;

  }

#elif defined(__FreeBSD__)

  // On FreeBSD if the exec path specified in ELF auxiliary vectors is

  // preferred, if available.  /proc/curproc/file and the KERN_PROC_PATHNAME

  // sysctl may not return the desired path if there are multiple hardlinks

  // to the file.

  char exe_path[PATH_MAX];

#if __FreeBSD_version >= 1300057

  if (elf_aux_info(AT_EXECPATH, exe_path, sizeof(exe_path)) == 0)

    return exe_path;

#else

  // elf_aux_info(AT_EXECPATH, ... is not available in all supported versions,

  // fall back to finding the ELF auxiliary vectors after the process's

  // environment.

  char **p = ::environ;

  while (*p++ != 0)

    ;

  // Iterate through auxiliary vectors for AT_EXECPATH.

  for (; *(uintptr_t *)p != AT_NULL; p++) {

    if (*(uintptr_t *)p++ == AT_EXECPATH)

      return *p;

  }

#endif

  // Fall back to argv[0] if auxiliary vectors are not available.

  if (getprogpath(exe_path, argv0) != NULL)

    return exe_path;

#elif defined(__NetBSD__) || defined(__OpenBSD__) || defined(__minix) ||       \

    defined(__DragonFly__) || defined(__FreeBSD_kernel__) || defined(_AIX)

  const char *curproc = "/proc/curproc/file";

  char exe_path[PATH_MAX];

  if (sys::fs::exists(curproc)) {

    ssize_t len = readlink(curproc, exe_path, sizeof(exe_path));

    if (len > 0) {

      // Null terminate the string for realpath. readlink never null

      // terminates its output.

      len = std::min(len, ssize_t(sizeof(exe_path) - 1));

      exe_path[len] = '\0';

      return exe_path;

    }

  }

  // If we don't have procfs mounted, fall back to argv[0]

  if (getprogpath(exe_path, argv0) != NULL)

    return exe_path;

#elif defined(__linux__) || defined(__CYGWIN__) || defined(__gnu_hurd__)

  char exe_path[PATH_MAX];

  const char *aPath = "/proc/self/exe";

  if (sys::fs::exists(aPath)) {

    // /proc is not always mounted under Linux (chroot for example).

    ssize_t len = readlink(aPath, exe_path, sizeof(exe_path));

    if (len < 0)

      return "";

    // Null terminate the string for realpath. readlink never null

    // terminates its output.

    len = std::min(len, ssize_t(sizeof(exe_path) - 1));

    exe_path[len] = '\0';

    // On Linux, /proc/self/exe always looks through symlinks. However, on

    // GNU/Hurd, /proc/self/exe is a symlink to the path that was used to start

    // the program, and not the eventual binary file. Therefore, call realpath

    // so this behaves the same on all platforms.

#if _POSIX_VERSION >= 200112 || defined(__GLIBC__)

    if (char *real_path = realpath(exe_path, NULL)) {

      std::string ret = std::string(real_path);

      free(real_path);

      return ret;

    }

#else

    char real_path[PATH_MAX];

    if (realpath(exe_path, real_path))

      return std::string(real_path);

#endif

  }

  // Fall back to the classical detection.

  if (getprogpath(exe_path, argv0))

    return exe_path;

#elif defined(HAVE_DLFCN_H) && defined(HAVE_DLADDR)

  // Use dladdr to get executable path if available.

  Dl_info DLInfo;

  int err = dladdr(MainAddr, &DLInfo);

  if (err == 0)

    return "";

  // If the filename is a symlink, we need to resolve and return the location of

  // the actual executable.

  char link_path[PATH_MAX];

  if (realpath(DLInfo.dli_fname, link_path))

    return link_path;

#else

#error GetMainExecutable is not implemented on this host yet.

#endif

  return "";

}

TimePoint<> basic_file_status::getLastAccessedTime() const {

  return toTimePoint(fs_st_atime, fs_st_atime_nsec);

}

TimePoint<> basic_file_status::getLastModificationTime() const {

  return toTimePoint(fs_st_mtime, fs_st_mtime_nsec);

}

UniqueID file_status::getUniqueID() const {

  return UniqueID(fs_st_dev, fs_st_ino);

}

uint32_t file_status::getLinkCount() const {

  return fs_st_nlinks;

}

ErrorOr<space_info> disk_space(const Twine &Path) {

  struct STATVFS Vfs;

  if (::STATVFS(const_cast<char *>(Path.str().c_str()), &Vfs))

    return std::error_code(errno, std::generic_category());

  auto FrSize = STATVFS_F_FRSIZE(Vfs);

  space_info SpaceInfo;

  SpaceInfo.capacity = static_cast<uint64_t>(Vfs.f_blocks) * FrSize;

  SpaceInfo.free = static_cast<uint64_t>(Vfs.f_bfree) * FrSize;

  SpaceInfo.available = static_cast<uint64_t>(Vfs.f_bavail) * FrSize;

  return SpaceInfo;

}

std::error_code current_path(SmallVectorImpl<char> &result) {

  result.clear();

  const char *pwd = ::getenv("PWD");

  llvm::sys::fs::file_status PWDStatus, DotStatus;

  if (pwd && llvm::sys::path::is_absolute(pwd) &&

      !llvm::sys::fs::status(pwd, PWDStatus) &&

      !llvm::sys::fs::status(".", DotStatus) &&

      PWDStatus.getUniqueID() == DotStatus.getUniqueID()) {

    result.append(pwd, pwd + strlen(pwd));

    return std::error_code();

  }

  result.reserve(PATH_MAX);

  while (true) {

    if (::getcwd(result.data(), result.capacity()) == nullptr) {

      // See if there was a real error.

      if (errno != ENOMEM)

        return std::error_code(errno, std::generic_category());

      // Otherwise there just wasn't enough space.

      result.reserve(result.capacity() * 2);

    } else

      break;

  }

  result.set_size(strlen(result.data()));

  return std::error_code();

}

std::error_code set_current_path(const Twine &path) {

  SmallString<128> path_storage;

  StringRef p = path.toNullTerminatedStringRef(path_storage);

  if (::chdir(p.begin()) == -1)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code create_directory(const Twine &path, bool IgnoreExisting,

                                 perms Perms) {

  SmallString<128> path_storage;

  StringRef p = path.toNullTerminatedStringRef(path_storage);

  if (::mkdir(p.begin(), Perms) == -1) {

    if (errno != EEXIST || !IgnoreExisting)

      return std::error_code(errno, std::generic_category());

  }

  return std::error_code();

}

// Note that we are using symbolic link because hard links are not supported by

// all filesystems (SMB doesn't).

std::error_code create_link(const Twine &to, const Twine &from) {

  // Get arguments.

  SmallString<128> from_storage;

  SmallString<128> to_storage;

  StringRef f = from.toNullTerminatedStringRef(from_storage);

  StringRef t = to.toNullTerminatedStringRef(to_storage);

  if (::symlink(t.begin(), f.begin()) == -1)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code create_hard_link(const Twine &to, const Twine &from) {

  // Get arguments.

  SmallString<128> from_storage;

  SmallString<128> to_storage;

  StringRef f = from.toNullTerminatedStringRef(from_storage);

  StringRef t = to.toNullTerminatedStringRef(to_storage);

  if (::link(t.begin(), f.begin()) == -1)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code remove(const Twine &path, bool IgnoreNonExisting) {

  SmallString<128> path_storage;

  StringRef p = path.toNullTerminatedStringRef(path_storage);

  struct stat buf;

  if (lstat(p.begin(), &buf) != 0) {

    if (errno != ENOENT || !IgnoreNonExisting)

      return std::error_code(errno, std::generic_category());

    return std::error_code();

  }

  // Note: this check catches strange situations. In all cases, LLVM should

  // only be involved in the creation and deletion of regular files.  This

  // check ensures that what we're trying to erase is a regular file. It

  // effectively prevents LLVM from erasing things like /dev/null, any block

  // special file, or other things that aren't "regular" files.

  if (!S_ISREG(buf.st_mode) && !S_ISDIR(buf.st_mode) && !S_ISLNK(buf.st_mode))

    return make_error_code(errc::operation_not_permitted);

  if (::remove(p.begin()) == -1) {

    if (errno != ENOENT || !IgnoreNonExisting)

      return std::error_code(errno, std::generic_category());

  }

  return std::error_code();

}

static bool is_local_impl(struct STATVFS &Vfs) {

#if defined(__linux__) || defined(__GNU__)

#ifndef NFS_SUPER_MAGIC

#define NFS_SUPER_MAGIC 0x6969

#endif

#ifndef SMB_SUPER_MAGIC

#define SMB_SUPER_MAGIC 0x517B

#endif

#ifndef CIFS_MAGIC_NUMBER

#define CIFS_MAGIC_NUMBER 0xFF534D42

#endif

#ifdef __GNU__

  switch ((uint32_t)Vfs.__f_type) {

#else

  switch ((uint32_t)Vfs.f_type) {

#endif

  case NFS_SUPER_MAGIC:

  case SMB_SUPER_MAGIC:

  case CIFS_MAGIC_NUMBER:

    return false;

  default:

    return true;

  }

#elif defined(__CYGWIN__)

  // Cygwin doesn't expose this information; would need to use Win32 API.

  return false;

#elif defined(__Fuchsia__)

  // Fuchsia doesn't yet support remote filesystem mounts.

  return true;

#elif defined(__EMSCRIPTEN__)

  // Emscripten doesn't currently support remote filesystem mounts.

  return true;

#elif defined(__HAIKU__)

  // Haiku doesn't expose this information.

  return false;

#elif defined(__sun)

  // statvfs::f_basetype contains a null-terminated FSType name of the mounted target

  StringRef fstype(Vfs.f_basetype);

  // NFS is the only non-local fstype??

  return !fstype.equals("nfs");

#elif defined(_AIX)

  // Call mntctl; try more than twice in case of timing issues with a concurrent

  // mount.

  int Ret;

  size_t BufSize = 2048u;

  std::unique_ptr<char[]> Buf;

  int Tries = 3;

  while (Tries--) {

    Buf = std::make_unique<char[]>(BufSize);

    Ret = mntctl(MCTL_QUERY, BufSize, Buf.get());

    if (Ret != 0)

      break;

    BufSize = *reinterpret_cast<unsigned int *>(Buf.get());

    Buf.reset();

  }

  if (Ret == -1)

    // There was an error; "remote" is the conservative answer.

    return false;

  // Look for the correct vmount entry.

  char *CurObjPtr = Buf.get();

  while (Ret--) {

    struct vmount *Vp = reinterpret_cast<struct vmount *>(CurObjPtr);

    static_assert(sizeof(Vfs.f_fsid) == sizeof(Vp->vmt_fsid),

                  "fsid length mismatch");

    if (memcmp(&Vfs.f_fsid, &Vp->vmt_fsid, sizeof Vfs.f_fsid) == 0)

      return (Vp->vmt_flags & MNT_REMOTE) == 0;

    CurObjPtr += Vp->vmt_length;

  }

  // vmount entry not found; "remote" is the conservative answer.

  return false;

#else

  return !!(STATVFS_F_FLAG(Vfs) & MNT_LOCAL);

#endif

}

std::error_code is_local(const Twine &Path, bool &Result) {

  struct STATVFS Vfs;

  if (::STATVFS(const_cast<char *>(Path.str().c_str()), &Vfs))

    return std::error_code(errno, std::generic_category());

  Result = is_local_impl(Vfs);

  return std::error_code();

}

std::error_code is_local(int FD, bool &Result) {

  struct STATVFS Vfs;

  if (::FSTATVFS(FD, &Vfs))

    return std::error_code(errno, std::generic_category());

  Result = is_local_impl(Vfs);

  return std::error_code();

}

std::error_code rename(const Twine &from, const Twine &to) {

  // Get arguments.

  SmallString<128> from_storage;

  SmallString<128> to_storage;

  StringRef f = from.toNullTerminatedStringRef(from_storage);

  StringRef t = to.toNullTerminatedStringRef(to_storage);

  if (::rename(f.begin(), t.begin()) == -1)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code resize_file(int FD, uint64_t Size) {

#if defined(HAVE_POSIX_FALLOCATE)

  // If we have posix_fallocate use it. Unlike ftruncate it always allocates

  // space, so we get an error if the disk is full.

  if (int Err = ::posix_fallocate(FD, 0, Size)) {

#ifdef _AIX

    constexpr int NotSupportedError = ENOTSUP;

#else

    constexpr int NotSupportedError = EOPNOTSUPP;

#endif

    if (Err != EINVAL && Err != NotSupportedError)

      return std::error_code(Err, std::generic_category());

  }

#endif

  // Use ftruncate as a fallback. It may or may not allocate space. At least on

  // OS X with HFS+ it does.

  if (::ftruncate(FD, Size) == -1)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

static int convertAccessMode(AccessMode Mode) {

  switch (Mode) {

  case AccessMode::Exist:

    return F_OK;

  case AccessMode::Write:

    return W_OK;

  case AccessMode::Execute:

    return R_OK | X_OK; // scripts also need R_OK.

  }

  llvm_unreachable("invalid enum");

}

std::error_code access(const Twine &Path, AccessMode Mode) {

  SmallString<128> PathStorage;

  StringRef P = Path.toNullTerminatedStringRef(PathStorage);

  if (::access(P.begin(), convertAccessMode(Mode)) == -1)

    return std::error_code(errno, std::generic_category());

  if (Mode == AccessMode::Execute) {

    // Don't say that directories are executable.

    struct stat buf;

    if (0 != stat(P.begin(), &buf))

      return errc::permission_denied;

    if (!S_ISREG(buf.st_mode))

      return errc::permission_denied;

  }

  return std::error_code();

}

bool can_execute(const Twine &Path) {

  return !access(Path, AccessMode::Execute);

}

bool equivalent(file_status A, file_status B) {

  assert(status_known(A) && status_known(B));

  return A.fs_st_dev == B.fs_st_dev &&

         A.fs_st_ino == B.fs_st_ino;

}

std::error_code equivalent(const Twine &A, const Twine &B, bool &result) {

  file_status fsA, fsB;

  if (std::error_code ec = status(A, fsA))

    return ec;

  if (std::error_code ec = status(B, fsB))

    return ec;

  result = equivalent(fsA, fsB);

  return std::error_code();

}

static void expandTildeExpr(SmallVectorImpl<char> &Path) {

  StringRef PathStr(Path.begin(), Path.size());

  if (PathStr.empty() || !PathStr.startswith("~"))

    return;

  PathStr = PathStr.drop_front();

  StringRef Expr =

      PathStr.take_until([](char c) { return path::is_separator(c); });

  StringRef Remainder = PathStr.substr(Expr.size() + 1);

  SmallString<128> Storage;

  if (Expr.empty()) {

    // This is just ~/..., resolve it to the current user's home dir.

    if (!path::home_directory(Storage)) {

      // For some reason we couldn't get the home directory.  Just exit.

      return;

    }

    // Overwrite the first character and insert the rest.

    Path[0] = Storage[0];

    Path.insert(Path.begin() + 1, Storage.begin() + 1, Storage.end());

    return;

  }

  // This is a string of the form ~username/, look up this user's entry in the

  // password database.

  struct passwd *Entry = nullptr;

  std::string User = Expr.str();

  Entry = ::getpwnam(User.c_str());

  if (!Entry) {

    // Unable to look up the entry, just return back the original path.

    return;

  }

  Storage = Remainder;

  Path.clear();

  Path.append(Entry->pw_dir, Entry->pw_dir + strlen(Entry->pw_dir));

  llvm::sys::path::append(Path, Storage);

}

void expand_tilde(const Twine &path, SmallVectorImpl<char> &dest) {

  dest.clear();

  if (path.isTriviallyEmpty())

    return;

  path.toVector(dest);

  expandTildeExpr(dest);

  return;

}

static file_type typeForMode(mode_t Mode) {

  if (S_ISDIR(Mode))

    return file_type::directory_file;

  else if (S_ISREG(Mode))

    return file_type::regular_file;

  else if (S_ISBLK(Mode))

    return file_type::block_file;

  else if (S_ISCHR(Mode))

    return file_type::character_file;

  else if (S_ISFIFO(Mode))

    return file_type::fifo_file;

  else if (S_ISSOCK(Mode))

    return file_type::socket_file;

  else if (S_ISLNK(Mode))

    return file_type::symlink_file;

  return file_type::type_unknown;

}

static std::error_code fillStatus(int StatRet, const struct stat &Status,

                                  file_status &Result) {

  if (StatRet != 0) {

    std::error_code EC(errno, std::generic_category());

    if (EC == errc::no_such_file_or_directory)

      Result = file_status(file_type::file_not_found);

    else

      Result = file_status(file_type::status_error);

    return EC;

  }

  uint32_t atime_nsec, mtime_nsec;

#if defined(HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC)

  atime_nsec = Status.st_atimespec.tv_nsec;

  mtime_nsec = Status.st_mtimespec.tv_nsec;

#elif defined(HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC)

  atime_nsec = Status.st_atim.tv_nsec;

  mtime_nsec = Status.st_mtim.tv_nsec;

#else

  atime_nsec = mtime_nsec = 0;

#endif

  perms Perms = static_cast<perms>(Status.st_mode) & all_perms;

  Result = file_status(typeForMode(Status.st_mode), Perms, Status.st_dev,

                       Status.st_nlink, Status.st_ino,

                       Status.st_atime, atime_nsec, Status.st_mtime, mtime_nsec,

                       Status.st_uid, Status.st_gid, Status.st_size);

  return std::error_code();

}

std::error_code status(const Twine &Path, file_status &Result, bool Follow) {

  SmallString<128> PathStorage;

  StringRef P = Path.toNullTerminatedStringRef(PathStorage);

  struct stat Status;

  int StatRet = (Follow ? ::stat : ::lstat)(P.begin(), &Status);

  return fillStatus(StatRet, Status, Result);

}

std::error_code status(int FD, file_status &Result) {

  struct stat Status;

  int StatRet = ::fstat(FD, &Status);

  return fillStatus(StatRet, Status, Result);

}

unsigned getUmask() {

  // Chose arbitary new mask and reset the umask to the old mask.

  // umask(2) never fails so ignore the return of the second call.

  unsigned Mask = ::umask(0);

  (void) ::umask(Mask);

  return Mask;

}

std::error_code setPermissions(const Twine &Path, perms Permissions) {

  SmallString<128> PathStorage;

  StringRef P = Path.toNullTerminatedStringRef(PathStorage);

  if (::chmod(P.begin(), Permissions))

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code setPermissions(int FD, perms Permissions) {

  if (::fchmod(FD, Permissions))

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

std::error_code setLastAccessAndModificationTime(int FD, TimePoint<> AccessTime,

                                                 TimePoint<> ModificationTime) {

#if defined(HAVE_FUTIMENS)

  timespec Times[2];

  Times[0] = sys::toTimeSpec(AccessTime);

  Times[1] = sys::toTimeSpec(ModificationTime);

  if (::futimens(FD, Times))

    return std::error_code(errno, std::generic_category());

  return std::error_code();

#elif defined(HAVE_FUTIMES)

  timeval Times[2];

  Times[0] = sys::toTimeVal(

      std::chrono::time_point_cast<std::chrono::microseconds>(AccessTime));

  Times[1] =

      sys::toTimeVal(std::chrono::time_point_cast<std::chrono::microseconds>(

          ModificationTime));

  if (::futimes(FD, Times))

    return std::error_code(errno, std::generic_category());

  return std::error_code();

#else

#warning Missing futimes() and futimens()

  return make_error_code(errc::function_not_supported);

#endif

}

std::error_code mapped_file_region::init(int FD, uint64_t Offset,

                                         mapmode Mode) {

  assert(Size != 0);

  int flags = (Mode == readwrite) ? MAP_SHARED : MAP_PRIVATE;

  int prot = (Mode == readonly) ? PROT_READ : (PROT_READ | PROT_WRITE);

#if defined(__APPLE__)

  //----------------------------------------------------------------------

  // Newer versions of MacOSX have a flag that will allow us to read from

  // binaries whose code signature is invalid without crashing by using

  // the MAP_RESILIENT_CODESIGN flag. Also if a file from removable media

  // is mapped we can avoid crashing and return zeroes to any pages we try

  // to read if the media becomes unavailable by using the

  // MAP_RESILIENT_MEDIA flag.  These flags are only usable when mapping

  // with PROT_READ, so take care not to specify them otherwise.

  //----------------------------------------------------------------------

  if (Mode == readonly) {

#if defined(MAP_RESILIENT_CODESIGN)

    flags |= MAP_RESILIENT_CODESIGN;

#endif

#if defined(MAP_RESILIENT_MEDIA)

    flags |= MAP_RESILIENT_MEDIA;

#endif

  }

#endif // #if defined (__APPLE__)

  Mapping = ::mmap(nullptr, Size, prot, flags, FD, Offset);

  if (Mapping == MAP_FAILED)

    return std::error_code(errno, std::generic_category());

  return std::error_code();

}

mapped_file_region::mapped_file_region(int fd, mapmode mode, size_t length,

                                       uint64_t offset, std::error_code &ec)

    : Size(length), Mapping(), Mode(mode) {

  (void)Mode;

  ec = init(fd, offset, mode);

  if (ec)

    Mapping = nullptr;

}

mapped_file_region::~mapped_file_region() {

  if (Mapping)

    ::munmap(Mapping, Size);

}

size_t mapped_file_region::size() const {

  assert(Mapping && "Mapping failed but used anyway!");

  return Size;

}

char *mapped_file_region::data() const {

  assert(Mapping && "Mapping failed but used anyway!");

  return reinterpret_cast<char*>(Mapping);

}

const char *mapped_file_region::const_data() const {

  assert(Mapping && "Mapping failed but used anyway!");

  return reinterpret_cast<const char*>(Mapping);

}

int mapped_file_region::alignment() {

  return Process::getPageSizeEstimate();

}

std::error_code detail::directory_iterator_construct(detail::DirIterState &it,

                                                     StringRef path,

                                                     bool follow_symlinks) {

  SmallString<128> path_null(path);

  DIR *directory = ::opendir(path_null.c_str());

  if (!directory)

    return std::error_code(errno, std::generic_category());

  it.IterationHandle = reinterpret_cast<intptr_t>(directory);

  // Add something for replace_filename to replace.

  path::append(path_null, ".");

  it.CurrentEntry = directory_entry(path_null.str(), follow_symlinks);

  return directory_iterator_increment(it);

}

std::error_code detail::directory_iterator_destruct(detail::DirIterState &it) {

  if (it.IterationHandle)

    ::closedir(reinterpret_cast<DIR *>(it.IterationHandle));

  it.IterationHandle = 0;

  it.CurrentEntry = directory_entry();

  return std::error_code();

}

static file_type direntType(dirent* Entry) {

  // Most platforms provide the file type in the dirent: Linux/BSD/Mac.

  // The DTTOIF macro lets us reuse our status -> type conversion.

  // Note that while glibc provides a macro to see if this is supported,

  // _DIRENT_HAVE_D_TYPE, it's not defined on BSD/Mac, so we test for the

  // d_type-to-mode_t conversion macro instead.

#if defined(DTTOIF)

  return typeForMode(DTTOIF(Entry->d_type));

#else

  // Other platforms such as Solaris require a stat() to get the type.

  return file_type::type_unknown;

#endif

}

std::error_code detail::directory_iterator_increment(detail::DirIterState &It) {

  errno = 0;

  dirent *CurDir = ::readdir(reinterpret_cast<DIR *>(It.IterationHandle));

  if (CurDir == nullptr && errno != 0) {

    return std::error_code(errno, std::generic_category());

  } else if (CurDir != nullptr) {

    StringRef Name(CurDir->d_name);

    if ((Name.size() == 1 && Name[0] == '.') ||

        (Name.size() == 2 && Name[0] == '.' && Name[1] == '.'))

      return directory_iterator_increment(It);

    It.CurrentEntry.replace_filename(Name, direntType(CurDir));

  } else

    return directory_iterator_destruct(It);

  return std::error_code();

}

ErrorOr<basic_file_status> directory_entry::status() const {

  file_status s;

  if (auto EC = fs::status(Path, s, FollowSymlinks))

    return EC;

  return s;

}

#if !defined(F_GETPATH)

static bool hasProcSelfFD() {

  // If we have a /proc filesystem mounted, we can quickly establish the

  // real name of the file with readlink

  static const bool Result = (::access("/proc/self/fd", R_OK) == 0);

  return Result;

}

#endif

static int nativeOpenFlags(CreationDisposition Disp, OpenFlags Flags,

                           FileAccess Access) {

  int Result = 0;

  if (Access == FA_Read)

    Result |= O_RDONLY;

  else if (Access == FA_Write)

    Result |= O_WRONLY;

  else if (Access == (FA_Read | FA_Write))

    Result |= O_RDWR;

  // This is for compatibility with old code that assumed OF_Append implied

  // would open an existing file.  See Windows/Path.inc for a longer comment.

  if (Flags & OF_Append)

    Disp = CD_OpenAlways;

  if (Disp == CD_CreateNew) {

    Result |= O_CREAT; // Create if it doesn't exist.

    Result |= O_EXCL;  // Fail if it does.

  } else if (Disp == CD_CreateAlways) {

    Result |= O_CREAT; // Create if it doesn't exist.

    Result |= O_TRUNC; // Truncate if it does.

  } else if (Disp == CD_OpenAlways) {

    Result |= O_CREAT; // Create if it doesn't exist.

  } else if (Disp == CD_OpenExisting) {

    // Nothing special, just don't add O_CREAT and we get these semantics.

  }

  if (Flags & OF_Append)

    Result |= O_APPEND;