//===- llvm/Support/FileSystem.h - File System OS Concept -------*- 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 declares the llvm::sys::fs namespace. It is designed after
 
// TR2/boost filesystem (v3), but modified to remove exception handling and the
 
// path class.
 
//
 
// All functions return an error_code and their actual work via the last out
 
// argument. The out argument is defined if and only if errc::success is
 
// returned. A function may return any error code in the generic or system
 
// category. However, they shall be equivalent to any error conditions listed
 
// in each functions respective documentation if the condition applies. [ note:
 
// this does not guarantee that error_code will be in the set of explicitly
 
// listed codes, but it does guarantee that if any of the explicitly listed
 
// errors occur, the correct error_code will be used ]. All functions may
 
// return errc::not_enough_memory if there is not enough memory to complete the
 
// operation.
 
//
 
//===----------------------------------------------------------------------===//
 
 
 
#ifndef LLVM_SUPPORT_FILESYSTEM_H
 
#define LLVM_SUPPORT_FILESYSTEM_H
 
 
 
#include "llvm/ADT/SmallString.h"
 
#include "llvm/ADT/StringRef.h"
 
#include "llvm/ADT/Twine.h"
 
#include "llvm/Config/llvm-config.h"
 
#include "llvm/Support/Chrono.h"
 
#include "llvm/Support/Error.h"
 
#include "llvm/Support/ErrorHandling.h"
 
#include "llvm/Support/ErrorOr.h"
 
#include "llvm/Support/FileSystem/UniqueID.h"
 
#include "llvm/Support/MD5.h"
 
#include <cassert>
 
#include <cstdint>
 
#include <ctime>
 
#include <memory>
 
#include <stack>
 
#include <string>
 
#include <system_error>
 
#include <vector>
 
 
 
#ifdef HAVE_SYS_STAT_H
 
#include <sys/stat.h>
 
#endif
 
 
 
namespace llvm {
 
namespace sys {
 
namespace fs {
 
 
 
#if defined(_WIN32)
 
// A Win32 HANDLE is a typedef of void*
 
using file_t = void *;
 
#else
 
using file_t = int;
 
#endif
 
 
 
extern const file_t kInvalidFile;
 
 
 
/// An enumeration for the file system's view of the type.
 
enum class file_type {
 
  status_error,
 
  file_not_found,
 
  regular_file,
 
  directory_file,
 
  symlink_file,
 
  block_file,
 
  character_file,
 
  fifo_file,
 
  socket_file,
 
  type_unknown
 
};
 
 
 
/// space_info - Self explanatory.
 
struct space_info {
 
  uint64_t capacity;
 
  uint64_t free;
 
  uint64_t available;
 
};
 
 
 
enum perms {
 
  no_perms = 0,
 
  owner_read = 0400,
 
  owner_write = 0200,
 
  owner_exe = 0100,
 
  owner_all = owner_read | owner_write | owner_exe,
 
  group_read = 040,
 
  group_write = 020,
 
  group_exe = 010,
 
  group_all = group_read | group_write | group_exe,
 
  others_read = 04,
 
  others_write = 02,
 
  others_exe = 01,
 
  others_all = others_read | others_write | others_exe,
 
  all_read = owner_read | group_read | others_read,
 
  all_write = owner_write | group_write | others_write,
 
  all_exe = owner_exe | group_exe | others_exe,
 
  all_all = owner_all | group_all | others_all,
 
  set_uid_on_exe = 04000,
 
  set_gid_on_exe = 02000,
 
  sticky_bit = 01000,
 
  all_perms = all_all | set_uid_on_exe | set_gid_on_exe | sticky_bit,
 
  perms_not_known = 0xFFFF
 
};
 
 
 
// Helper functions so that you can use & and | to manipulate perms bits:
 
inline perms operator|(perms l, perms r) {
 
  return static_cast<perms>(static_cast<unsigned short>(l) |
 
                            static_cast<unsigned short>(r));
 
}
 
inline perms operator&(perms l, perms r) {
 
  return static_cast<perms>(static_cast<unsigned short>(l) &
 
                            static_cast<unsigned short>(r));
 
}
 
inline perms &operator|=(perms &l, perms r) {
 
  l = l | r;
 
  return l;
 
}
 
inline perms &operator&=(perms &l, perms r) {
 
  l = l & r;
 
  return l;
 
}
 
inline perms operator~(perms x) {
 
  // Avoid UB by explicitly truncating the (unsigned) ~ result.
 
  return static_cast<perms>(
 
      static_cast<unsigned short>(~static_cast<unsigned short>(x)));
 
}
 
 
 
/// Represents the result of a call to directory_iterator::status(). This is a
 
/// subset of the information returned by a regular sys::fs::status() call, and
 
/// represents the information provided by Windows FileFirstFile/FindNextFile.
 
class basic_file_status {
 
protected:
 
  #if defined(LLVM_ON_UNIX)
 
  time_t fs_st_atime = 0;
 
  time_t fs_st_mtime = 0;
 
  uint32_t fs_st_atime_nsec = 0;
 
  uint32_t fs_st_mtime_nsec = 0;
 
  uid_t fs_st_uid = 0;
 
  gid_t fs_st_gid = 0;
 
  off_t fs_st_size = 0;
 
  #elif defined (_WIN32)
 
  uint32_t LastAccessedTimeHigh = 0;
 
  uint32_t LastAccessedTimeLow = 0;
 
  uint32_t LastWriteTimeHigh = 0;
 
  uint32_t LastWriteTimeLow = 0;
 
  uint32_t FileSizeHigh = 0;
 
  uint32_t FileSizeLow = 0;
 
  #endif
 
  file_type Type = file_type::status_error;
 
  perms Perms = perms_not_known;
 
 
 
public:
 
  basic_file_status() = default;
 
 
 
  explicit basic_file_status(file_type Type) : Type(Type) {}
 
 
 
  #if defined(LLVM_ON_UNIX)
 
  basic_file_status(file_type Type, perms Perms, time_t ATime,
 
                    uint32_t ATimeNSec, time_t MTime, uint32_t MTimeNSec,
 
                    uid_t UID, gid_t GID, off_t Size)
 
      : fs_st_atime(ATime), fs_st_mtime(MTime),
 
        fs_st_atime_nsec(ATimeNSec), fs_st_mtime_nsec(MTimeNSec),
 
        fs_st_uid(UID), fs_st_gid(GID),
 
        fs_st_size(Size), Type(Type), Perms(Perms) {}
 
#elif defined(_WIN32)
 
  basic_file_status(file_type Type, perms Perms, uint32_t LastAccessTimeHigh,
 
                    uint32_t LastAccessTimeLow, uint32_t LastWriteTimeHigh,
 
                    uint32_t LastWriteTimeLow, uint32_t FileSizeHigh,
 
                    uint32_t FileSizeLow)
 
      : LastAccessedTimeHigh(LastAccessTimeHigh),
 
        LastAccessedTimeLow(LastAccessTimeLow),
 
        LastWriteTimeHigh(LastWriteTimeHigh),
 
        LastWriteTimeLow(LastWriteTimeLow), FileSizeHigh(FileSizeHigh),
 
        FileSizeLow(FileSizeLow), Type(Type), Perms(Perms) {}
 
  #endif
 
 
 
  // getters
 
  file_type type() const { return Type; }
 
  perms permissions() const { return Perms; }
 
 
 
  /// The file access time as reported from the underlying file system.
 
  ///
 
  /// Also see comments on \c getLastModificationTime() related to the precision
 
  /// of the returned value.
 
  TimePoint<> getLastAccessedTime() const;
 
 
 
  /// The file modification time as reported from the underlying file system.
 
  ///
 
  /// The returned value allows for nanosecond precision but the actual
 
  /// resolution is an implementation detail of the underlying file system.
 
  /// There is no guarantee for what kind of resolution you can expect, the
 
  /// resolution can differ across platforms and even across mountpoints on the
 
  /// same machine.
 
  TimePoint<> getLastModificationTime() const;
 
 
 
  #if defined(LLVM_ON_UNIX)
 
  uint32_t getUser() const { return fs_st_uid; }
 
  uint32_t getGroup() const { return fs_st_gid; }
 
  uint64_t getSize() const { return fs_st_size; }
 
  #elif defined (_WIN32)
 
  uint32_t getUser() const {
 
    return 9999; // Not applicable to Windows, so...
 
  }
 
 
 
  uint32_t getGroup() const {
 
    return 9999; // Not applicable to Windows, so...
 
  }
 
 
 
  uint64_t getSize() const {
 
    return (uint64_t(FileSizeHigh) << 32) + FileSizeLow;
 
  }
 
  #endif
 
 
 
  // setters
 
  void type(file_type v) { Type = v; }
 
  void permissions(perms p) { Perms = p; }
 
};
 
 
 
/// Represents the result of a call to sys::fs::status().
 
class file_status : public basic_file_status {
 
  friend bool equivalent(file_status A, file_status B);
 
 
 
  #if defined(LLVM_ON_UNIX)
 
  dev_t fs_st_dev = 0;
 
  nlink_t fs_st_nlinks = 0;
 
  ino_t fs_st_ino = 0;
 
  #elif defined (_WIN32)
 
  uint32_t NumLinks = 0;
 
  uint32_t VolumeSerialNumber = 0;
 
  uint32_t FileIndexHigh = 0;
 
  uint32_t FileIndexLow = 0;
 
  #endif
 
 
 
public:
 
  file_status() = default;
 
 
 
  explicit file_status(file_type Type) : basic_file_status(Type) {}
 
 
 
  #if defined(LLVM_ON_UNIX)
 
  file_status(file_type Type, perms Perms, dev_t Dev, nlink_t Links, ino_t Ino,
 
              time_t ATime, uint32_t ATimeNSec,
 
              time_t MTime, uint32_t MTimeNSec,
 
              uid_t UID, gid_t GID, off_t Size)
 
      : basic_file_status(Type, Perms, ATime, ATimeNSec, MTime, MTimeNSec,
 
                          UID, GID, Size),
 
        fs_st_dev(Dev), fs_st_nlinks(Links), fs_st_ino(Ino) {}
 
  #elif defined(_WIN32)
 
  file_status(file_type Type, perms Perms, uint32_t LinkCount,
 
              uint32_t LastAccessTimeHigh, uint32_t LastAccessTimeLow,
 
              uint32_t LastWriteTimeHigh, uint32_t LastWriteTimeLow,
 
              uint32_t VolumeSerialNumber, uint32_t FileSizeHigh,
 
              uint32_t FileSizeLow, uint32_t FileIndexHigh,
 
              uint32_t FileIndexLow)
 
      : basic_file_status(Type, Perms, LastAccessTimeHigh, LastAccessTimeLow,
 
                          LastWriteTimeHigh, LastWriteTimeLow, FileSizeHigh,
 
                          FileSizeLow),
 
        NumLinks(LinkCount), VolumeSerialNumber(VolumeSerialNumber),
 
        FileIndexHigh(FileIndexHigh), FileIndexLow(FileIndexLow) {}
 
  #endif
 
 
 
  UniqueID getUniqueID() const;
 
  uint32_t getLinkCount() const;
 
};
 
 
 
/// @}
 
/// @name Physical Operators
 
/// @{
 
 
 
/// Make \a path an absolute path.
 
///
 
/// Makes \a path absolute using the \a current_directory if it is not already.
 
/// An empty \a path will result in the \a current_directory.
 
///
 
/// /absolute/path   => /absolute/path
 
/// relative/../path => <current-directory>/relative/../path
 
///
 
/// @param path A path that is modified to be an absolute path.
 
void make_absolute(const Twine ¤t_directory, SmallVectorImpl<char> &path);
 
 
 
/// Make \a path an absolute path.
 
///
 
/// Makes \a path absolute using the current directory if it is not already. An
 
/// empty \a path will result in the current directory.
 
///
 
/// /absolute/path   => /absolute/path
 
/// relative/../path => <current-directory>/relative/../path
 
///
 
/// @param path A path that is modified to be an absolute path.
 
/// @returns errc::success if \a path has been made absolute, otherwise a
 
///          platform-specific error_code.
 
std::error_code make_absolute(SmallVectorImpl<char> &path);
 
 
 
/// Create all the non-existent directories in path.
 
///
 
/// @param path Directories to create.
 
/// @returns errc::success if is_directory(path), otherwise a platform
 
///          specific error_code. If IgnoreExisting is false, also returns
 
///          error if the directory already existed.
 
std::error_code create_directories(const Twine &path,
 
                                   bool IgnoreExisting = true,
 
                                   perms Perms = owner_all | group_all);
 
 
 
/// Create the directory in path.
 
///
 
/// @param path Directory to create.
 
/// @returns errc::success if is_directory(path), otherwise a platform
 
///          specific error_code. If IgnoreExisting is false, also returns
 
///          error if the directory already existed.
 
std::error_code create_directory(const Twine &path, bool IgnoreExisting = true,
 
                                 perms Perms = owner_all | group_all);
 
 
 
/// Create a link from \a from to \a to.
 
///
 
/// The link may be a soft or a hard link, depending on the platform. The caller
 
/// may not assume which one. Currently on windows it creates a hard link since
 
/// soft links require extra privileges. On unix, it creates a soft link since
 
/// hard links don't work on SMB file systems.
 
///
 
/// @param to The path to hard link to.
 
/// @param from The path to hard link from. This is created.
 
/// @returns errc::success if the link was created, otherwise a platform
 
/// specific error_code.
 
std::error_code create_link(const Twine &to, const Twine &from);
 
 
 
/// Create a hard link from \a from to \a to, or return an error.
 
///
 
/// @param to The path to hard link to.
 
/// @param from The path to hard link from. This is created.
 
/// @returns errc::success if the link was created, otherwise a platform
 
/// specific error_code.
 
std::error_code create_hard_link(const Twine &to, const Twine &from);
 
 
 
/// Collapse all . and .. patterns, resolve all symlinks, and optionally
 
///        expand ~ expressions to the user's home directory.
 
///
 
/// @param path The path to resolve.
 
/// @param output The location to store the resolved path.
 
/// @param expand_tilde If true, resolves ~ expressions to the user's home
 
///                     directory.
 
std::error_code real_path(const Twine &path, SmallVectorImpl<char> &output,
 
                          bool expand_tilde = false);
 
 
 
/// Expands ~ expressions to the user's home directory. On Unix ~user
 
/// directories are resolved as well.
 
///
 
/// @param path The path to resolve.
 
void expand_tilde(const Twine &path, SmallVectorImpl<char> &output);
 
 
 
/// Get the current path.
 
///
 
/// @param result Holds the current path on return.
 
/// @returns errc::success if the current path has been stored in result,
 
///          otherwise a platform-specific error_code.
 
std::error_code current_path(SmallVectorImpl<char> &result);
 
 
 
/// Set the current path.
 
///
 
/// @param path The path to set.
 
/// @returns errc::success if the current path was successfully set,
 
///          otherwise a platform-specific error_code.
 
std::error_code set_current_path(const Twine &path);
 
 
 
/// Remove path. Equivalent to POSIX remove().
 
///
 
/// @param path Input path.
 
/// @returns errc::success if path has been removed or didn't exist, otherwise a
 
///          platform-specific error code. If IgnoreNonExisting is false, also
 
///          returns error if the file didn't exist.
 
std::error_code remove(const Twine &path, bool IgnoreNonExisting = true);
 
 
 
/// Recursively delete a directory.
 
///
 
/// @param path Input path.
 
/// @returns errc::success if path has been removed or didn't exist, otherwise a
 
///          platform-specific error code.
 
std::error_code remove_directories(const Twine &path, bool IgnoreErrors = true);
 
 
 
/// Rename \a from to \a to.
 
///
 
/// Files are renamed as if by POSIX rename(), except that on Windows there may
 
/// be a short interval of time during which the destination file does not
 
/// exist.
 
///
 
/// @param from The path to rename from.
 
/// @param to The path to rename to. This is created.
 
std::error_code rename(const Twine &from, const Twine &to);
 
 
 
/// Copy the contents of \a From to \a To.
 
///
 
/// @param From The path to copy from.
 
/// @param To The path to copy to. This is created.
 
std::error_code copy_file(const Twine &From, const Twine &To);
 
 
 
/// Copy the contents of \a From to \a To.
 
///
 
/// @param From The path to copy from.
 
/// @param ToFD The open file descriptor of the destination file.
 
std::error_code copy_file(const Twine &From, int ToFD);
 
 
 
/// Resize path to size. File is resized as if by POSIX truncate().
 
///
 
/// @param FD Input file descriptor.
 
/// @param Size Size to resize to.
 
/// @returns errc::success if \a path has been resized to \a size, otherwise a
 
///          platform-specific error_code.
 
std::error_code resize_file(int FD, uint64_t Size);
 
 
 
/// Resize \p FD to \p Size before mapping \a mapped_file_region::readwrite. On
 
/// non-Windows, this calls \a resize_file(). On Windows, this is a no-op,
 
/// since the subsequent mapping (via \c CreateFileMapping) automatically
 
/// extends the file.
 
inline std::error_code resize_file_before_mapping_readwrite(int FD,
 
                                                            uint64_t Size) {
 
#ifdef _WIN32
 
  (void)FD;
 
  (void)Size;
 
  return std::error_code();
 
#else
 
  return resize_file(FD, Size);
 
#endif
 
}
 
 
 
/// Compute an MD5 hash of a file's contents.
 
///
 
/// @param FD Input file descriptor.
 
/// @returns An MD5Result with the hash computed, if successful, otherwise a
 
///          std::error_code.
 
ErrorOr<MD5::MD5Result> md5_contents(int FD);
 
 
 
/// Version of compute_md5 that doesn't require an open file descriptor.
 
ErrorOr<MD5::MD5Result> md5_contents(const Twine &Path);
 
 
 
/// @}
 
/// @name Physical Observers
 
/// @{
 
 
 
/// Does file exist?
 
///
 
/// @param status A basic_file_status previously returned from stat.
 
/// @returns True if the file represented by status exists, false if it does
 
///          not.
 
bool exists(const basic_file_status &status);
 
 
 
enum class AccessMode { Exist, Write, Execute };
 
 
 
/// Can the file be accessed?
 
///
 
/// @param Path Input path.
 
/// @returns errc::success if the path can be accessed, otherwise a
 
///          platform-specific error_code.
 
std::error_code access(const Twine &Path, AccessMode Mode);
 
 
 
/// Does file exist?
 
///
 
/// @param Path Input path.
 
/// @returns True if it exists, false otherwise.
 
inline bool exists(const Twine &Path) {
 
  return !access(Path, AccessMode::Exist);
 
}
 
 
 
/// Can we execute this file?
 
///
 
/// @param Path Input path.
 
/// @returns True if we can execute it, false otherwise.
 
bool can_execute(const Twine &Path);
 
 
 
/// Can we write this file?
 
///
 
/// @param Path Input path.
 
/// @returns True if we can write to it, false otherwise.
 
inline bool can_write(const Twine &Path) {
 
  return !access(Path, AccessMode::Write);
 
}
 
 
 
/// Do file_status's represent the same thing?
 
///
 
/// @param A Input file_status.
 
/// @param B Input file_status.
 
///
 
/// assert(status_known(A) || status_known(B));
 
///
 
/// @returns True if A and B both represent the same file system entity, false
 
///          otherwise.
 
bool equivalent(file_status A, file_status B);
 
 
 
/// Do paths represent the same thing?
 
///
 
/// assert(status_known(A) || status_known(B));
 
///
 
/// @param A Input path A.
 
/// @param B Input path B.
 
/// @param result Set to true if stat(A) and stat(B) have the same device and
 
///               inode (or equivalent).
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code equivalent(const Twine &A, const Twine &B, bool &result);
 
 
 
/// Simpler version of equivalent for clients that don't need to
 
///        differentiate between an error and false.
 
inline bool equivalent(const Twine &A, const Twine &B) {
 
  bool result;
 
  return !equivalent(A, B, result) && result;
 
}
 
 
 
/// Is the file mounted on a local filesystem?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if \a path is on fixed media such as a hard disk,
 
///               false if it is not.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform specific error_code.
 
std::error_code is_local(const Twine &path, bool &result);
 
 
 
/// Version of is_local accepting an open file descriptor.
 
std::error_code is_local(int FD, bool &result);
 
 
 
/// Simpler version of is_local for clients that don't need to
 
///        differentiate between an error and false.
 
inline bool is_local(const Twine &Path) {
 
  bool Result;
 
  return !is_local(Path, Result) && Result;
 
}
 
 
 
/// Simpler version of is_local accepting an open file descriptor for
 
///        clients that don't need to differentiate between an error and false.
 
inline bool is_local(int FD) {
 
  bool Result;
 
  return !is_local(FD, Result) && Result;
 
}
 
 
 
/// Does status represent a directory?
 
///
 
/// @param Path The path to get the type of.
 
/// @param Follow For symbolic links, indicates whether to return the file type
 
///               of the link itself, or of the target.
 
/// @returns A value from the file_type enumeration indicating the type of file.
 
file_type get_file_type(const Twine &Path, bool Follow = true);
 
 
 
/// Does status represent a directory?
 
///
 
/// @param status A basic_file_status previously returned from status.
 
/// @returns status.type() == file_type::directory_file.
 
bool is_directory(const basic_file_status &status);
 
 
 
/// Is path a directory?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if \a path is a directory (after following
 
///               symlinks, false if it is not. Undefined otherwise.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code is_directory(const Twine &path, bool &result);
 
 
 
/// Simpler version of is_directory for clients that don't need to
 
///        differentiate between an error and false.
 
inline bool is_directory(const Twine &Path) {
 
  bool Result;
 
  return !is_directory(Path, Result) && Result;
 
}
 
 
 
/// Does status represent a regular file?
 
///
 
/// @param status A basic_file_status previously returned from status.
 
/// @returns status_known(status) && status.type() == file_type::regular_file.
 
bool is_regular_file(const basic_file_status &status);
 
 
 
/// Is path a regular file?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if \a path is a regular file (after following
 
///               symlinks), false if it is not. Undefined otherwise.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code is_regular_file(const Twine &path, bool &result);
 
 
 
/// Simpler version of is_regular_file for clients that don't need to
 
///        differentiate between an error and false.
 
inline bool is_regular_file(const Twine &Path) {
 
  bool Result;
 
  if (is_regular_file(Path, Result))
 
    return false;
 
  return Result;
 
}
 
 
 
/// Does status represent a symlink file?
 
///
 
/// @param status A basic_file_status previously returned from status.
 
/// @returns status_known(status) && status.type() == file_type::symlink_file.
 
bool is_symlink_file(const basic_file_status &status);
 
 
 
/// Is path a symlink file?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if \a path is a symlink file, false if it is not.
 
///               Undefined otherwise.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code is_symlink_file(const Twine &path, bool &result);
 
 
 
/// Simpler version of is_symlink_file for clients that don't need to
 
///        differentiate between an error and false.
 
inline bool is_symlink_file(const Twine &Path) {
 
  bool Result;
 
  if (is_symlink_file(Path, Result))
 
    return false;
 
  return Result;
 
}
 
 
 
/// Does this status represent something that exists but is not a
 
///        directory or regular file?
 
///
 
/// @param status A basic_file_status previously returned from status.
 
/// @returns exists(s) && !is_regular_file(s) && !is_directory(s)
 
bool is_other(const basic_file_status &status);
 
 
 
/// Is path something that exists but is not a directory,
 
///        regular file, or symlink?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if \a path exists, but is not a directory, regular
 
///               file, or a symlink, false if it does not. Undefined otherwise.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code is_other(const Twine &path, bool &result);
 
 
 
/// Get file status as if by POSIX stat().
 
///
 
/// @param path Input path.
 
/// @param result Set to the file status.
 
/// @param follow When true, follows symlinks.  Otherwise, the symlink itself is
 
///               statted.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code status(const Twine &path, file_status &result,
 
                       bool follow = true);
 
 
 
/// A version for when a file descriptor is already available.
 
std::error_code status(int FD, file_status &Result);
 
 
 
#ifdef _WIN32
 
/// A version for when a file descriptor is already available.
 
std::error_code status(file_t FD, file_status &Result);
 
#endif
 
 
 
/// Get file creation mode mask of the process.
 
///
 
/// @returns Mask reported by umask(2)
 
/// @note There is no umask on Windows. This function returns 0 always
 
///       on Windows. This function does not return an error_code because
 
///       umask(2) never fails. It is not thread safe.
 
unsigned getUmask();
 
 
 
/// Set file permissions.
 
///
 
/// @param Path File to set permissions on.
 
/// @param Permissions New file permissions.
 
/// @returns errc::success if the permissions were successfully set, otherwise
 
///          a platform-specific error_code.
 
/// @note On Windows, all permissions except *_write are ignored. Using any of
 
///       owner_write, group_write, or all_write will make the file writable.
 
///       Otherwise, the file will be marked as read-only.
 
std::error_code setPermissions(const Twine &Path, perms Permissions);
 
 
 
/// Vesion of setPermissions accepting a file descriptor.
 
/// TODO Delete the path based overload once we implement the FD based overload
 
/// on Windows.
 
std::error_code setPermissions(int FD, perms Permissions);
 
 
 
/// Get file permissions.
 
///
 
/// @param Path File to get permissions from.
 
/// @returns the permissions if they were successfully retrieved, otherwise a
 
///          platform-specific error_code.
 
/// @note On Windows, if the file does not have the FILE_ATTRIBUTE_READONLY
 
///       attribute, all_all will be returned. Otherwise, all_read | all_exe
 
///       will be returned.
 
ErrorOr<perms> getPermissions(const Twine &Path);
 
 
 
/// Get file size.
 
///
 
/// @param Path Input path.
 
/// @param Result Set to the size of the file in \a Path.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
inline std::error_code file_size(const Twine &Path, uint64_t &Result) {
 
  file_status Status;
 
  std::error_code EC = status(Path, Status);
 
  if (EC)
 
    return EC;
 
  Result = Status.getSize();
 
  return std::error_code();
 
}
 
 
 
/// Set the file modification and access time.
 
///
 
/// @returns errc::success if the file times were successfully set, otherwise a
 
///          platform-specific error_code or errc::function_not_supported on
 
///          platforms where the functionality isn't available.
 
std::error_code setLastAccessAndModificationTime(int FD, TimePoint<> AccessTime,
 
                                                 TimePoint<> ModificationTime);
 
 
 
/// Simpler version that sets both file modification and access time to the same
 
/// time.
 
inline std::error_code setLastAccessAndModificationTime(int FD,
 
                                                        TimePoint<> Time) {
 
  return setLastAccessAndModificationTime(FD, Time, Time);
 
}
 
 
 
/// Is status available?
 
///
 
/// @param s Input file status.
 
/// @returns True if status() != status_error.
 
bool status_known(const basic_file_status &s);
 
 
 
/// Is status available?
 
///
 
/// @param path Input path.
 
/// @param result Set to true if status() != status_error.
 
/// @returns errc::success if result has been successfully set, otherwise a
 
///          platform-specific error_code.
 
std::error_code status_known(const Twine &path, bool &result);
 
 
 
enum CreationDisposition : unsigned {
 
  /// CD_CreateAlways - When opening a file:
 
  ///   * If it already exists, truncate it.
 
  ///   * If it does not already exist, create a new file.
 
  CD_CreateAlways = 0,
 
 
 
  /// CD_CreateNew - When opening a file:
 
  ///   * If it already exists, fail.
 
  ///   * If it does not already exist, create a new file.
 
  CD_CreateNew = 1,
 
 
 
  /// CD_OpenExisting - When opening a file:
 
  ///   * If it already exists, open the file with the offset set to 0.
 
  ///   * If it does not already exist, fail.
 
  CD_OpenExisting = 2,
 
 
 
  /// CD_OpenAlways - When opening a file:
 
  ///   * If it already exists, open the file with the offset set to 0.
 
  ///   * If it does not already exist, create a new file.
 
  CD_OpenAlways = 3,
 
};
 
 
 
enum FileAccess : unsigned {
 
  FA_Read = 1,
 
  FA_Write = 2,
 
};
 
 
 
enum OpenFlags : unsigned {
 
  OF_None = 0,
 
 
 
  /// The file should be opened in text mode on platforms like z/OS that make
 
  /// this distinction.
 
  OF_Text = 1,
 
 
 
  /// The file should use a carriage linefeed '\r\n'. This flag should only be
 
  /// used with OF_Text. Only makes a difference on Windows.
 
  OF_CRLF = 2,
 
 
 
  /// The file should be opened in text mode and use a carriage linefeed '\r\n'.
 
  /// This flag has the same functionality as OF_Text on z/OS but adds a
 
  /// carriage linefeed on Windows.
 
  OF_TextWithCRLF = OF_Text | OF_CRLF,
 
 
 
  /// The file should be opened in append mode.
 
  OF_Append = 4,
 
 
 
  /// The returned handle can be used for deleting the file. Only makes a
 
  /// difference on windows.
 
  OF_Delete = 8,
 
 
 
  /// When a child process is launched, this file should remain open in the
 
  /// child process.
 
  OF_ChildInherit = 16,
 
 
 
  /// Force files Atime to be updated on access. Only makes a difference on
 
  /// Windows.
 
  OF_UpdateAtime = 32,
 
};
 
 
 
/// Create a potentially unique file name but does not create it.
 
///
 
/// Generates a unique path suitable for a temporary file but does not
 
/// open or create the file. The name is based on \a Model with '%'
 
/// replaced by a random char in [0-9a-f]. If \a MakeAbsolute is true
 
/// then the system's temp directory is prepended first. If \a MakeAbsolute
 
/// is false the current directory will be used instead.
 
///
 
/// This function does not check if the file exists. If you want to be sure
 
/// that the file does not yet exist, you should use use enough '%' characters
 
/// in your model to ensure this. Each '%' gives 4-bits of entropy so you can
 
/// use 32 of them to get 128 bits of entropy.
 
///
 
/// Example: clang-%%-%%-%%-%%-%%.s => clang-a0-b1-c2-d3-e4.s
 
///
 
/// @param Model Name to base unique path off of.
 
/// @param ResultPath Set to the file's path.
 
/// @param MakeAbsolute Whether to use the system temp directory.
 
void createUniquePath(const Twine &Model, SmallVectorImpl<char> &ResultPath,
 
                      bool MakeAbsolute);
 
 
 
/// Create a uniquely named file.
 
///
 
/// Generates a unique path suitable for a temporary file and then opens it as a
 
/// file. The name is based on \a Model with '%' replaced by a random char in
 
/// [0-9a-f]. If \a Model is not an absolute path, the temporary file will be
 
/// created in the current directory.
 
///
 
/// Example: clang-%%-%%-%%-%%-%%.s => clang-a0-b1-c2-d3-e4.s
 
///
 
/// This is an atomic operation. Either the file is created and opened, or the
 
/// file system is left untouched.
 
///
 
/// The intended use is for files that are to be kept, possibly after
 
/// renaming them. For example, when running 'clang -c foo.o', the file can
 
/// be first created as foo-abc123.o and then renamed.
 
///
 
/// @param Model Name to base unique path off of.
 
/// @param ResultFD Set to the opened file's file descriptor.
 
/// @param ResultPath Set to the opened file's absolute path.
 
/// @param Flags Set to the opened file's flags.
 
/// @param Mode Set to the opened file's permissions.
 
/// @returns errc::success if Result{FD,Path} have been successfully set,
 
///          otherwise a platform-specific error_code.
 
std::error_code createUniqueFile(const Twine &Model, int &ResultFD,
 
                                 SmallVectorImpl<char> &ResultPath,
 
                                 OpenFlags Flags = OF_None,
 
                                 unsigned Mode = all_read | all_write);
 
 
 
/// Simpler version for clients that don't want an open file. An empty
 
/// file will still be created.
 
std::error_code createUniqueFile(const Twine &Model,
 
                                 SmallVectorImpl<char> &ResultPath,
 
                                 unsigned Mode = all_read | all_write);
 
 
 
/// Represents a temporary file.
 
///
 
/// The temporary file must be eventually discarded or given a final name and
 
/// kept.
 
///
 
/// The destructor doesn't implicitly discard because there is no way to
 
/// properly handle errors in a destructor.
 
class TempFile {
 
  bool Done = false;
 
  TempFile(StringRef Name, int FD);
 
 
 
public:
 
  /// This creates a temporary file with createUniqueFile and schedules it for
 
  /// deletion with sys::RemoveFileOnSignal.
 
  static Expected<TempFile> create(const Twine &Model,
 
                                   unsigned Mode = all_read | all_write,
 
                                   OpenFlags ExtraFlags = OF_None);
 
  TempFile(TempFile &&Other);
 
  TempFile &operator=(TempFile &&Other);
 
 
 
  // Name of the temporary file.
 
  std::string TmpName;
 
 
 
  // The open file descriptor.
 
  int FD = -1;
 
 
 
#ifdef _WIN32
 
  // Whether we need to manually remove the file on close.
 
  bool RemoveOnClose = false;
 
#endif
 
 
 
  // Keep this with the given name.
 
  Error keep(const Twine &Name);
 
 
 
  // Keep this with the temporary name.
 
  Error keep();
 
 
 
  // Delete the file.
 
  Error discard();
 
 
 
  // This checks that keep or delete was called.
 
  ~TempFile();
 
};
 
 
 
/// Create a file in the system temporary directory.
 
///
 
/// The filename is of the form prefix-random_chars.suffix. Since the directory
 
/// is not know to the caller, Prefix and Suffix cannot have path separators.
 
/// The files are created with mode 0600.
 
///
 
/// This should be used for things like a temporary .s that is removed after
 
/// running the assembler.
 
std::error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
 
                                    int &ResultFD,
 
                                    SmallVectorImpl<char> &ResultPath,
 
                                    OpenFlags Flags = OF_None);
 
 
 
/// Simpler version for clients that don't want an open file. An empty
 
/// file will still be created.
 
std::error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
 
                                    SmallVectorImpl<char> &ResultPath,
 
                                    OpenFlags Flags = OF_None);
 
 
 
std::error_code createUniqueDirectory(const Twine &Prefix,
 
                                      SmallVectorImpl<char> &ResultPath);
 
 
 
/// Get a unique name, not currently exisiting in the filesystem. Subject
 
/// to race conditions, prefer to use createUniqueFile instead.
 
///
 
/// Similar to createUniqueFile, but instead of creating a file only
 
/// checks if it exists. This function is subject to race conditions, if you
 
/// want to use the returned name to actually create a file, use
 
/// createUniqueFile instead.
 
std::error_code getPotentiallyUniqueFileName(const Twine &Model,
 
                                             SmallVectorImpl<char> &ResultPath);
 
 
 
/// Get a unique temporary file name, not currently exisiting in the
 
/// filesystem. Subject to race conditions, prefer to use createTemporaryFile
 
/// instead.
 
///
 
/// Similar to createTemporaryFile, but instead of creating a file only
 
/// checks if it exists. This function is subject to race conditions, if you
 
/// want to use the returned name to actually create a file, use
 
/// createTemporaryFile instead.
 
std::error_code
 
getPotentiallyUniqueTempFileName(const Twine &Prefix, StringRef Suffix,
 
                                 SmallVectorImpl<char> &ResultPath);
 
 
 
inline OpenFlags operator|(OpenFlags A, OpenFlags B) {
 
  return OpenFlags(unsigned(A) | unsigned(B));
 
}
 
 
 
inline OpenFlags &operator|=(OpenFlags &A, OpenFlags B) {
 
  A = A | B;
 
  return A;
 
}
 
 
 
inline FileAccess operator|(FileAccess A, FileAccess B) {
 
  return FileAccess(unsigned(A) | unsigned(B));
 
}
 
 
 
inline FileAccess &operator|=(FileAccess &A, FileAccess B) {
 
  A = A | B;
 
  return A;
 
}
 
 
 
/// @brief Opens a file with the specified creation disposition, access mode,
 
/// and flags and returns a file descriptor.
 
///
 
/// The caller is responsible for closing the file descriptor once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param ResultFD If the file could be opened successfully, its descriptor
 
///                 is stored in this location. Otherwise, this is set to -1.
 
/// @param Disp Value specifying the existing-file behavior.
 
/// @param Access Value specifying whether to open the file in read, write, or
 
///               read-write mode.
 
/// @param Flags Additional flags.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns errc::success if \a Name has been opened, otherwise a
 
///          platform-specific error_code.
 
std::error_code openFile(const Twine &Name, int &ResultFD,
 
                         CreationDisposition Disp, FileAccess Access,
 
                         OpenFlags Flags, unsigned Mode = 0666);
 
 
 
/// @brief Opens a file with the specified creation disposition, access mode,
 
/// and flags and returns a platform-specific file object.
 
///
 
/// The caller is responsible for closing the file object once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param Disp Value specifying the existing-file behavior.
 
/// @param Access Value specifying whether to open the file in read, write, or
 
///               read-write mode.
 
/// @param Flags Additional flags.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns errc::success if \a Name has been opened, otherwise a
 
///          platform-specific error_code.
 
Expected<file_t> openNativeFile(const Twine &Name, CreationDisposition Disp,
 
                                FileAccess Access, OpenFlags Flags,
 
                                unsigned Mode = 0666);
 
 
 
/// Converts from a Posix file descriptor number to a native file handle.
 
/// On Windows, this retreives the underlying handle. On non-Windows, this is a
 
/// no-op.
 
file_t convertFDToNativeFile(int FD);
 
 
 
#ifndef _WIN32
 
inline file_t convertFDToNativeFile(int FD) { return FD; }
 
#endif
 
 
 
/// Return an open handle to standard in. On Unix, this is typically FD 0.
 
/// Returns kInvalidFile when the stream is closed.
 
file_t getStdinHandle();
 
 
 
/// Return an open handle to standard out. On Unix, this is typically FD 1.
 
/// Returns kInvalidFile when the stream is closed.
 
file_t getStdoutHandle();
 
 
 
/// Return an open handle to standard error. On Unix, this is typically FD 2.
 
/// Returns kInvalidFile when the stream is closed.
 
file_t getStderrHandle();
 
 
 
/// Reads \p Buf.size() bytes from \p FileHandle into \p Buf. Returns the number
 
/// of bytes actually read. On Unix, this is equivalent to `return ::read(FD,
 
/// Buf.data(), Buf.size())`, with error reporting. Returns 0 when reaching EOF.
 
///
 
/// @param FileHandle File to read from.
 
/// @param Buf Buffer to read into.
 
/// @returns The number of bytes read, or error.
 
Expected<size_t> readNativeFile(file_t FileHandle, MutableArrayRef<char> Buf);
 
 
 
/// Default chunk size for \a readNativeFileToEOF().
 
enum : size_t { DefaultReadChunkSize = 4 * 4096 };
 
 
 
/// Reads from \p FileHandle until EOF, appending to \p Buffer in chunks of
 
/// size \p ChunkSize.
 
///
 
/// This calls \a readNativeFile() in a loop. On Error, previous chunks that
 
/// were read successfully are left in \p Buffer and returned.
 
///
 
/// Note: For reading the final chunk at EOF, \p Buffer's capacity needs extra
 
/// storage of \p ChunkSize.
 
///
 
/// \param FileHandle File to read from.
 
/// \param Buffer Where to put the file content.
 
/// \param ChunkSize Size of chunks.
 
/// \returns The error if EOF was not found.
 
Error readNativeFileToEOF(file_t FileHandle, SmallVectorImpl<char> &Buffer,
 
                          ssize_t ChunkSize = DefaultReadChunkSize);
 
 
 
/// Reads \p Buf.size() bytes from \p FileHandle at offset \p Offset into \p
 
/// Buf. If 'pread' is available, this will use that, otherwise it will use
 
/// 'lseek'. Returns the number of bytes actually read. Returns 0 when reaching
 
/// EOF.
 
///
 
/// @param FileHandle File to read from.
 
/// @param Buf Buffer to read into.
 
/// @param Offset Offset into the file at which the read should occur.
 
/// @returns The number of bytes read, or error.
 
Expected<size_t> readNativeFileSlice(file_t FileHandle,
 
                                     MutableArrayRef<char> Buf,
 
                                     uint64_t Offset);
 
 
 
/// @brief Opens the file with the given name in a write-only or read-write
 
/// mode, returning its open file descriptor. If the file does not exist, it
 
/// is created.
 
///
 
/// The caller is responsible for closing the file descriptor once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param ResultFD If the file could be opened successfully, its descriptor
 
///                 is stored in this location. Otherwise, this is set to -1.
 
/// @param Flags Additional flags used to determine whether the file should be
 
///              opened in, for example, read-write or in write-only mode.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns errc::success if \a Name has been opened, otherwise a
 
///          platform-specific error_code.
 
inline std::error_code
 
openFileForWrite(const Twine &Name, int &ResultFD,
 
                 CreationDisposition Disp = CD_CreateAlways,
 
                 OpenFlags Flags = OF_None, unsigned Mode = 0666) {
 
  return openFile(Name, ResultFD, Disp, FA_Write, Flags, Mode);
 
}
 
 
 
/// @brief Opens the file with the given name in a write-only or read-write
 
/// mode, returning its open file descriptor. If the file does not exist, it
 
/// is created.
 
///
 
/// The caller is responsible for closing the freeing the file once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param Flags Additional flags used to determine whether the file should be
 
///              opened in, for example, read-write or in write-only mode.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns a platform-specific file descriptor if \a Name has been opened,
 
///          otherwise an error object.
 
inline Expected<file_t> openNativeFileForWrite(const Twine &Name,
 
                                               CreationDisposition Disp,
 
                                               OpenFlags Flags,
 
                                               unsigned Mode = 0666) {
 
  return openNativeFile(Name, Disp, FA_Write, Flags, Mode);
 
}
 
 
 
/// @brief Opens the file with the given name in a write-only or read-write
 
/// mode, returning its open file descriptor. If the file does not exist, it
 
/// is created.
 
///
 
/// The caller is responsible for closing the file descriptor once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param ResultFD If the file could be opened successfully, its descriptor
 
///                 is stored in this location. Otherwise, this is set to -1.
 
/// @param Flags Additional flags used to determine whether the file should be
 
///              opened in, for example, read-write or in write-only mode.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns errc::success if \a Name has been opened, otherwise a
 
///          platform-specific error_code.
 
inline std::error_code openFileForReadWrite(const Twine &Name, int &ResultFD,
 
                                            CreationDisposition Disp,
 
                                            OpenFlags Flags,
 
                                            unsigned Mode = 0666) {
 
  return openFile(Name, ResultFD, Disp, FA_Write | FA_Read, Flags, Mode);
 
}
 
 
 
/// @brief Opens the file with the given name in a write-only or read-write
 
/// mode, returning its open file descriptor. If the file does not exist, it
 
/// is created.
 
///
 
/// The caller is responsible for closing the freeing the file once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param Flags Additional flags used to determine whether the file should be
 
///              opened in, for example, read-write or in write-only mode.
 
/// @param Mode The access permissions of the file, represented in octal.
 
/// @returns a platform-specific file descriptor if \a Name has been opened,
 
///          otherwise an error object.
 
inline Expected<file_t> openNativeFileForReadWrite(const Twine &Name,
 
                                                   CreationDisposition Disp,
 
                                                   OpenFlags Flags,
 
                                                   unsigned Mode = 0666) {
 
  return openNativeFile(Name, Disp, FA_Write | FA_Read, Flags, Mode);
 
}
 
 
 
/// @brief Opens the file with the given name in a read-only mode, returning
 
/// its open file descriptor.
 
///
 
/// The caller is responsible for closing the file descriptor once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param ResultFD If the file could be opened successfully, its descriptor
 
///                 is stored in this location. Otherwise, this is set to -1.
 
/// @param RealPath If nonnull, extra work is done to determine the real path
 
///                 of the opened file, and that path is stored in this
 
///                 location.
 
/// @returns errc::success if \a Name has been opened, otherwise a
 
///          platform-specific error_code.
 
std::error_code openFileForRead(const Twine &Name, int &ResultFD,
 
                                OpenFlags Flags = OF_None,
 
                                SmallVectorImpl<char> *RealPath = nullptr);
 
 
 
/// @brief Opens the file with the given name in a read-only mode, returning
 
/// its open file descriptor.
 
///
 
/// The caller is responsible for closing the freeing the file once they are
 
/// finished with it.
 
///
 
/// @param Name The path of the file to open, relative or absolute.
 
/// @param RealPath If nonnull, extra work is done to determine the real path
 
///                 of the opened file, and that path is stored in this
 
///                 location.
 
/// @returns a platform-specific file descriptor if \a Name has been opened,
 
///          otherwise an error object.
 
Expected<file_t>
 
openNativeFileForRead(const Twine &Name, OpenFlags Flags = OF_None,
 
                      SmallVectorImpl<char> *RealPath = nullptr);
 
 
 
/// Try to locks the file during the specified time.
 
///
 
/// This function implements advisory locking on entire file. If it returns
 
/// <em>errc::success</em>, the file is locked by the calling process. Until the
 
/// process unlocks the file by calling \a unlockFile, all attempts to lock the
 
/// same file will fail/block. The process that locked the file may assume that
 
/// none of other processes read or write this file, provided that all processes
 
/// lock the file prior to accessing its content.
 
///
 
/// @param FD      The descriptor representing the file to lock.
 
/// @param Timeout Time in milliseconds that the process should wait before
 
///                reporting lock failure. Zero value means try to get lock only
 
///                once.
 
/// @returns errc::success if lock is successfully obtained,
 
/// errc::no_lock_available if the file cannot be locked, or platform-specific
 
/// error_code otherwise.
 
///
 
/// @note Care should be taken when using this function in a multithreaded
 
/// context, as it may not prevent other threads in the same process from
 
/// obtaining a lock on the same file, even if they are using a different file
 
/// descriptor.
 
std::error_code
 
tryLockFile(int FD,
 
            std::chrono::milliseconds Timeout = std::chrono::milliseconds(0));
 
 
 
/// Lock the file.
 
///
 
/// This function acts as @ref tryLockFile but it waits infinitely.
 
std::error_code lockFile(int FD);
 
 
 
/// Unlock the file.
 
///
 
/// @param FD The descriptor representing the file to unlock.
 
/// @returns errc::success if lock is successfully released or platform-specific
 
/// error_code otherwise.
 
std::error_code unlockFile(int FD);
 
 
 
/// @brief Close the file object.  This should be used instead of ::close for
 
/// portability. On error, the caller should assume the file is closed, as is
 
/// the case for Process::SafelyCloseFileDescriptor
 
///
 
/// @param F On input, this is the file to close.  On output, the file is
 
/// set to kInvalidFile.
 
///
 
/// @returns An error code if closing the file failed. Typically, an error here
 
/// means that the filesystem may have failed to perform some buffered writes.
 
std::error_code closeFile(file_t &F);
 
 
 
#ifdef LLVM_ON_UNIX
 
/// @brief Change ownership of a file.
 
///
 
/// @param Owner The owner of the file to change to.
 
/// @param Group The group of the file to change to.
 
/// @returns errc::success if successfully updated file ownership, otherwise an
 
///          error code is returned.
 
std::error_code changeFileOwnership(int FD, uint32_t Owner, uint32_t Group);
 
#endif
 
 
 
/// RAII class that facilitates file locking.
 
class FileLocker {
 
  int FD; ///< Locked file handle.
 
  FileLocker(int FD) : FD(FD) {}
 
  friend class llvm::raw_fd_ostream;
 
 
 
public:
 
  FileLocker(const FileLocker &L) = delete;
 
  FileLocker(FileLocker &&L) : FD(L.FD) { L.FD = -1; }
 
  ~FileLocker() {
 
    if (FD != -1)
 
      unlockFile(FD);
 
  }
 
  FileLocker &operator=(FileLocker &&L) {
 
    FD = L.FD;
 
    L.FD = -1;
 
    return *this;
 
  }
 
  FileLocker &operator=(const FileLocker &L) = delete;
 
  std::error_code unlock() {
 
    if (FD != -1) {
 
      std::error_code Result = unlockFile(FD);
 
      FD = -1;
 
      return Result;
 
    }
 
    return std::error_code();
 
  }
 
};
 
 
 
std::error_code getUniqueID(const Twine Path, UniqueID &Result);
 
 
 
/// Get disk space usage information.
 
///
 
/// Note: Users must be careful about "Time Of Check, Time Of Use" kind of bug.
 
/// Note: Windows reports results according to the quota allocated to the user.
 
///
 
/// @param Path Input path.
 
/// @returns a space_info structure filled with the capacity, free, and
 
/// available space on the device \a Path is on. A platform specific error_code
 
/// is returned on error.
 
ErrorOr<space_info> disk_space(const Twine &Path);
 
 
 
/// This class represents a memory mapped file. It is based on
 
/// boost::iostreams::mapped_file.
 
class mapped_file_region {
 
public:
 
  enum mapmode {
 
    readonly, ///< May only access map via const_data as read only.
 
    readwrite, ///< May access map via data and modify it. Written to path.
 
    priv ///< May modify via data, but changes are lost on destruction.
 
  };
 
 
 
private:
 
  /// Platform-specific mapping state.
 
  size_t Size = 0;
 
  void *Mapping = nullptr;
 
#ifdef _WIN32
 
  sys::fs::file_t FileHandle = nullptr;
 
#endif
 
  mapmode Mode = readonly;
 
 
 
  void copyFrom(const mapped_file_region &Copied) {
 
    Size = Copied.Size;
 
    Mapping = Copied.Mapping;
 
#ifdef _WIN32
 
    FileHandle = Copied.FileHandle;
 
#endif
 
    Mode = Copied.Mode;
 
  }
 
 
 
  void moveFromImpl(mapped_file_region &Moved) {
 
    copyFrom(Moved);
 
    Moved.copyFrom(mapped_file_region());
 
  }
 
 
 
  void unmapImpl();
 
  void dontNeedImpl();
 
 
 
  std::error_code init(sys::fs::file_t FD, uint64_t Offset, mapmode Mode);
 
 
 
public:
 
  mapped_file_region() = default;
 
  mapped_file_region(mapped_file_region &&Moved) { moveFromImpl(Moved); }
 
  mapped_file_region &operator=(mapped_file_region &&Moved) {
 
    unmap();
 
    moveFromImpl(Moved);
 
    return *this;
 
  }
 
 
 
  mapped_file_region(const mapped_file_region &) = delete;
 
  mapped_file_region &operator=(const mapped_file_region &) = delete;
 
 
 
  /// \param fd An open file descriptor to map. Does not take ownership of fd.
 
  mapped_file_region(sys::fs::file_t fd, mapmode mode, size_t length, uint64_t offset,
 
                     std::error_code &ec);
 
 
 
  ~mapped_file_region() { unmapImpl(); }
 
 
 
  /// Check if this is a valid mapping.
 
  explicit operator bool() const { return Mapping; }
 
 
 
  /// Unmap.
 
  void unmap() {
 
    unmapImpl();
 
    copyFrom(mapped_file_region());
 
  }
 
  void dontNeed() { dontNeedImpl(); }
 
 
 
  size_t size() const;
 
  char *data() const;
 
 
 
  /// Get a const view of the data. Modifying this memory has undefined
 
  /// behavior.
 
  const char *const_data() const;
 
 
 
  /// \returns The minimum alignment offset must be.
 
  static int alignment();
 
};
 
 
 
/// Return the path to the main executable, given the value of argv[0] from
 
/// program startup and the address of main itself. In extremis, this function
 
/// may fail and return an empty path.
 
std::string getMainExecutable(const char *argv0, void *MainExecAddr);
 
 
 
/// @}
 
/// @name Iterators
 
/// @{
 
 
 
/// directory_entry - A single entry in a directory.
 
class directory_entry {
 
  // FIXME: different platforms make different information available "for free"
 
  // when traversing a directory. The design of this class wraps most of the
 
  // information in basic_file_status, so on platforms where we can't populate
 
  // that whole structure, callers end up paying for a stat().
 
  // std::filesystem::directory_entry may be a better model.
 
  std::string Path;
 
  file_type Type = file_type::type_unknown; // Most platforms can provide this.
 
  bool FollowSymlinks = true;               // Affects the behavior of status().
 
  basic_file_status Status;                 // If available.
 
 
 
public:
 
  explicit directory_entry(const Twine &Path, bool FollowSymlinks = true,
 
                           file_type Type = file_type::type_unknown,
 
                           basic_file_status Status = basic_file_status())
 
      : Path(Path.str()), Type(Type), FollowSymlinks(FollowSymlinks),
 
        Status(Status) {}
 
 
 
  directory_entry() = default;
 
 
 
  void replace_filename(const Twine &Filename, file_type Type,
 
                        basic_file_status Status = basic_file_status());
 
 
 
  const std::string &path() const { return Path; }
 
  // Get basic information about entry file (a subset of fs::status()).
 
  // On most platforms this is a stat() call.
 
  // On windows the information was already retrieved from the directory.
 
  ErrorOr<basic_file_status> status() const;
 
  // Get the type of this file.
 
  // On most platforms (Linux/Mac/Windows/BSD), this was already retrieved.
 
  // On some platforms (e.g. Solaris) this is a stat() call.
 
  file_type type() const {
 
    if (Type != file_type::type_unknown)
 
      return Type;
 
    auto S = status();
 
    return S ? S->type() : file_type::type_unknown;
 
  }
 
 
 
  bool operator==(const directory_entry& RHS) const { return Path == RHS.Path; }
 
  bool operator!=(const directory_entry& RHS) const { return !(*this == RHS); }
 
  bool operator< (const directory_entry& RHS) const;
 
  bool operator<=(const directory_entry& RHS) const;
 
  bool operator> (const directory_entry& RHS) const;
 
  bool operator>=(const directory_entry& RHS) const;
 
};
 
 
 
namespace detail {
 
 
 
  struct DirIterState;
 
 
 
  std::error_code directory_iterator_construct(DirIterState &, StringRef, bool);
 
  std::error_code directory_iterator_increment(DirIterState &);
 
  std::error_code directory_iterator_destruct(DirIterState &);
 
 
 
  /// Keeps state for the directory_iterator.
 
  struct DirIterState {
 
    ~DirIterState() {
 
      directory_iterator_destruct(*this);
 
    }
 
 
 
    intptr_t IterationHandle = 0;
 
    directory_entry CurrentEntry;
 
  };
 
 
 
} // end namespace detail
 
 
 
/// directory_iterator - Iterates through the entries in path. There is no
 
/// operator++ because we need an error_code. If it's really needed we can make
 
/// it call report_fatal_error on error.
 
class directory_iterator {
 
  std::shared_ptr<detail::DirIterState> State;
 
  bool FollowSymlinks = true;
 
 
 
public:
 
  explicit directory_iterator(const Twine &path, std::error_code &ec,
 
                              bool follow_symlinks = true)
 
      : FollowSymlinks(follow_symlinks) {
 
    State = std::make_shared<detail::DirIterState>();
 
    SmallString<128> path_storage;
 
    ec = detail::directory_iterator_construct(
 
        *State, path.toStringRef(path_storage), FollowSymlinks);
 
  }
 
 
 
  explicit directory_iterator(const directory_entry &de, std::error_code &ec,
 
                              bool follow_symlinks = true)
 
      : FollowSymlinks(follow_symlinks) {
 
    State = std::make_shared<detail::DirIterState>();
 
    ec = detail::directory_iterator_construct(
 
        *State, de.path(), FollowSymlinks);
 
  }
 
 
 
  /// Construct end iterator.
 
  directory_iterator() = default;
 
 
 
  // No operator++ because we need error_code.
 
  directory_iterator &increment(std::error_code &ec) {
 
    ec = directory_iterator_increment(*State);
 
    return *this;
 
  }
 
 
 
  const directory_entry &operator*() const { return State->CurrentEntry; }
 
  const directory_entry *operator->() const { return &State->CurrentEntry; }
 
 
 
  bool operator==(const directory_iterator &RHS) const {
 
    if (State == RHS.State)
 
      return true;
 
    if (!RHS.State)
 
      return State->CurrentEntry == directory_entry();
 
    if (!State)
 
      return RHS.State->CurrentEntry == directory_entry();
 
    return State->CurrentEntry == RHS.State->CurrentEntry;
 
  }
 
 
 
  bool operator!=(const directory_iterator &RHS) const {
 
    return !(*this == RHS);
 
  }
 
};
 
 
 
namespace detail {
 
 
 
  /// Keeps state for the recursive_directory_iterator.
 
  struct RecDirIterState {
 
    std::stack<directory_iterator, std::vector<directory_iterator>> Stack;
 
    uint16_t Level = 0;
 
    bool HasNoPushRequest = false;
 
  };
 
 
 
} // end namespace detail
 
 
 
/// recursive_directory_iterator - Same as directory_iterator except for it
 
/// recurses down into child directories.
 
class recursive_directory_iterator {
 
  std::shared_ptr<detail::RecDirIterState> State;
 
  bool Follow;
 
 
 
public:
 
  recursive_directory_iterator() = default;
 
  explicit recursive_directory_iterator(const Twine &path, std::error_code &ec,
 
                                        bool follow_symlinks = true)
 
      : State(std::make_shared<detail::RecDirIterState>()),
 
        Follow(follow_symlinks) {
 
    State->Stack.push(directory_iterator(path, ec, Follow));
 
    if (State->Stack.top() == directory_iterator())
 
      State.reset();
 
  }
 
 
 
  // No operator++ because we need error_code.
 
  recursive_directory_iterator &increment(std::error_code &ec) {
 
    const directory_iterator end_itr = {};
 
 
 
    if (State->HasNoPushRequest)
 
      State->HasNoPushRequest = false;
 
    else {
 
      file_type type = State->Stack.top()->type();
 
      if (type == file_type::symlink_file && Follow) {
 
        // Resolve the symlink: is it a directory to recurse into?
 
        ErrorOr<basic_file_status> status = State->Stack.top()->status();
 
        if (status)
 
          type = status->type();
 
        // Otherwise broken symlink, and we'll continue.
 
      }
 
      if (type == file_type::directory_file) {
 
        State->Stack.push(directory_iterator(*State->Stack.top(), ec, Follow));
 
        if (State->Stack.top() != end_itr) {
 
          ++State->Level;
 
          return *this;
 
        }
 
        State->Stack.pop();
 
      }
 
    }
 
 
 
    while (!State->Stack.empty()
 
           && State->Stack.top().increment(ec) == end_itr) {
 
      State->Stack.pop();
 
      --State->Level;
 
    }
 
 
 
    // Check if we are done. If so, create an end iterator.
 
    if (State->Stack.empty())
 
      State.reset();
 
 
 
    return *this;
 
  }
 
 
 
  const directory_entry &operator*() const { return *State->Stack.top(); }
 
  const directory_entry *operator->() const { return &*State->Stack.top(); }
 
 
 
  // observers
 
  /// Gets the current level. Starting path is at level 0.
 
  int level() const { return State->Level; }
 
 
 
  /// Returns true if no_push has been called for this directory_entry.
 
  bool no_push_request() const { return State->HasNoPushRequest; }
 
 
 
  // modifiers
 
  /// Goes up one level if Level > 0.
 
  void pop() {
 
    assert(State && "Cannot pop an end iterator!");
 
    assert(State->Level > 0 && "Cannot pop an iterator with level < 1");
 
 
 
    const directory_iterator end_itr = {};
 
    std::error_code ec;
 
    do {
 
      if (ec)
 
        report_fatal_error("Error incrementing directory iterator.");
 
      State->Stack.pop();
 
      --State->Level;
 
    } while (!State->Stack.empty()
 
             && State->Stack.top().increment(ec) == end_itr);
 
 
 
    // Check if we are done. If so, create an end iterator.
 
    if (State->Stack.empty())
 
      State.reset();
 
  }
 
 
 
  /// Does not go down into the current directory_entry.
 
  void no_push() { State->HasNoPushRequest = true; }
 
 
 
  bool operator==(const recursive_directory_iterator &RHS) const {
 
    return State == RHS.State;
 
  }
 
 
 
  bool operator!=(const recursive_directory_iterator &RHS) const {
 
    return !(*this == RHS);
 
  }
 
};
 
 
 
/// @}
 
 
 
} // end namespace fs
 
} // end namespace sys
 
} // end namespace llvm
 
 
 
#endif // LLVM_SUPPORT_FILESYSTEM_H