//===- 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/Support/Chrono.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/Program.h"
#include <optional>
#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 std::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 std::optional<std::string>
FindInEnvPath(StringRef EnvName, StringRef FileName,
ArrayRef<std::string> IgnoreList,
char Separator = EnvPathSeparator);
static std::optional<std::string>
FindInEnvPath(StringRef EnvName, StringRef FileName,
char Separator = EnvPathSeparator);
// 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.
/// Use \arg NoCleanup for calling _exit() instead of exit().
[[noreturn]] static void Exit(int RetCode, bool NoCleanup = false);
private:
[[noreturn]] static void ExitNoCleanup(int RetCode);
};
}
}
#endif