//===- llvm/Support/Process.h -----------------------------------*- 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

//

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

/// \file

///

/// Provides a library for accessing information about this process and other

/// processes on the operating system. Also provides means of spawning

/// subprocess for commands. The design of this library is modeled after the

/// proposed design of the Boost.Process library, and is design specifically to

/// follow the style of standard libraries and potentially become a proposal

/// for a standard library.

///

/// This file declares the llvm::sys::Process class which contains a collection

/// of legacy static interfaces for extracting various information about the

/// current process. The goal is to migrate users of this API over to the new

/// interfaces.

///

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

#ifndef LLVM_SUPPORT_PROCESS_H

#define LLVM_SUPPORT_PROCESS_H

#include "llvm/ADT/Optional.h"

#include "llvm/Support/AllocatorBase.h"

#include "llvm/Support/Chrono.h"

#include "llvm/Support/DataTypes.h"

#include "llvm/Support/Error.h"

#include <system_error>

namespace llvm {

template <typename T> class ArrayRef;

class StringRef;

namespace sys {

/// A collection of legacy interfaces for querying information about the

/// current executing process.

class Process {

public:

  using Pid = int32_t;

  /// Get the process's identifier.

  static Pid getProcessId();

  /// Get the process's page size.

  /// This may fail if the underlying syscall returns an error. In most cases,

  /// page size information is used for optimization, and this error can be

  /// safely discarded by calling consumeError, and an estimated page size

  /// substituted instead.

  static Expected<unsigned> getPageSize();

  /// Get the process's estimated page size.

  /// This function always succeeds, but if the underlying syscall to determine

  /// the page size fails then this will silently return an estimated page size.

  /// The estimated page size is guaranteed to be a power of 2.

  static unsigned getPageSizeEstimate() {

    if (auto PageSize = getPageSize())

      return *PageSize;

    else {

      consumeError(PageSize.takeError());

      return 4096;

    }

  }

  /// Return process memory usage.

  /// This static function will return the total amount of memory allocated

  /// by the process. This only counts the memory allocated via the malloc,

  /// calloc and realloc functions and includes any "free" holes in the

  /// allocated space.

  static size_t GetMallocUsage();

  /// This static function will set \p user_time to the amount of CPU time

  /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU

  /// time spent in system (kernel) mode.  If the operating system does not

  /// support collection of these metrics, a zero duration will be for both

  /// values.

  /// \param elapsed Returns the system_clock::now() giving current time

  /// \param user_time Returns the current amount of user time for the process

  /// \param sys_time Returns the current amount of system time for the process

  static void GetTimeUsage(TimePoint<> &elapsed,

                           std::chrono::nanoseconds &user_time,

                           std::chrono::nanoseconds &sys_time);

  /// This function makes the necessary calls to the operating system to

  /// prevent core files or any other kind of large memory dumps that can

  /// occur when a program fails.

  /// Prevent core file generation.

  static void PreventCoreFiles();

  /// true if PreventCoreFiles has been called, false otherwise.

  static bool AreCoreFilesPrevented();

  // This function returns the environment variable \arg name's value as a UTF-8

  // string. \arg Name is assumed to be in UTF-8 encoding too.

  static Optional<std::string> GetEnv(StringRef name);

  /// This function searches for an existing file in the list of directories

  /// in a PATH like environment variable, and returns the first file found,

  /// according to the order of the entries in the PATH like environment

  /// variable.  If an ignore list is specified, then any folder which is in

  /// the PATH like environment variable but is also in IgnoreList is not

  /// considered.

  static Optional<std::string> FindInEnvPath(StringRef EnvName,

                                             StringRef FileName,

                                             ArrayRef<std::string> IgnoreList);

  static Optional<std::string> FindInEnvPath(StringRef EnvName,

                                             StringRef FileName);

  // This functions ensures that the standard file descriptors (input, output,

  // and error) are properly mapped to a file descriptor before we use any of

  // them.  This should only be called by standalone programs, library

  // components should not call this.

  static std::error_code FixupStandardFileDescriptors();

  // This function safely closes a file descriptor.  It is not safe to retry

  // close(2) when it returns with errno equivalent to EINTR; this is because

  // *nixen cannot agree if the file descriptor is, in fact, closed when this

  // occurs.

  //

  // N.B. Some operating systems, due to thread cancellation, cannot properly

  // guarantee that it will or will not be closed one way or the other!

  static std::error_code SafelyCloseFileDescriptor(int FD);

  /// This function determines if the standard input is connected directly

  /// to a user's input (keyboard probably), rather than coming from a file

  /// or pipe.

  static bool StandardInIsUserInput();

  /// This function determines if the standard output is connected to a

  /// "tty" or "console" window. That is, the output would be displayed to

  /// the user rather than being put on a pipe or stored in a file.

  static bool StandardOutIsDisplayed();

  /// This function determines if the standard error is connected to a

  /// "tty" or "console" window. That is, the output would be displayed to

  /// the user rather than being put on a pipe or stored in a file.

  static bool StandardErrIsDisplayed();

  /// This function determines if the given file descriptor is connected to

  /// a "tty" or "console" window. That is, the output would be displayed to

  /// the user rather than being put on a pipe or stored in a file.

  static bool FileDescriptorIsDisplayed(int fd);

  /// This function determines if the given file descriptor is displayd and

  /// supports colors.

  static bool FileDescriptorHasColors(int fd);

  /// This function determines the number of columns in the window

  /// if standard output is connected to a "tty" or "console"

  /// window. If standard output is not connected to a tty or

  /// console, or if the number of columns cannot be determined,

  /// this routine returns zero.

  static unsigned StandardOutColumns();

  /// This function determines the number of columns in the window

  /// if standard error is connected to a "tty" or "console"

  /// window. If standard error is not connected to a tty or

  /// console, or if the number of columns cannot be determined,

  /// this routine returns zero.

  static unsigned StandardErrColumns();

  /// This function determines whether the terminal connected to standard

  /// output supports colors. If standard output is not connected to a

  /// terminal, this function returns false.

  static bool StandardOutHasColors();

  /// This function determines whether the terminal connected to standard

  /// error supports colors. If standard error is not connected to a

  /// terminal, this function returns false.

  static bool StandardErrHasColors();

  /// Enables or disables whether ANSI escape sequences are used to output

  /// colors. This only has an effect on Windows.

  /// Note: Setting this option is not thread-safe and should only be done

  /// during initialization.

  static void UseANSIEscapeCodes(bool enable);

  /// Whether changing colors requires the output to be flushed.

  /// This is needed on systems that don't support escape sequences for

  /// changing colors.

  static bool ColorNeedsFlush();

  /// This function returns the colorcode escape sequences.

  /// If ColorNeedsFlush() is true then this function will change the colors

  /// and return an empty escape sequence. In that case it is the

  /// responsibility of the client to flush the output stream prior to

  /// calling this function.

  static const char *OutputColor(char c, bool bold, bool bg);

  /// Same as OutputColor, but only enables the bold attribute.

  static const char *OutputBold(bool bg);

  /// This function returns the escape sequence to reverse forground and

  /// background colors.

  static const char *OutputReverse();

  /// Resets the terminals colors, or returns an escape sequence to do so.

  static const char *ResetColor();

  /// Get the result of a process wide random number generator. The

  /// generator will be automatically seeded in non-deterministic fashion.

  static unsigned GetRandomNumber();

  /// Equivalent to ::exit(), except when running inside a CrashRecoveryContext.

  /// In that case, the control flow will resume after RunSafely(), like for a

  /// crash, rather than exiting the current process.

  LLVM_ATTRIBUTE_NORETURN

  static void Exit(int RetCode);

};

}

}

#endif