include/llvm/Support/Process.h

   1 //===- llvm/Support/Process.h -----------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 /// \file
   9 ///
  10 /// Provides a library for accessing information about this process and other
  11 /// processes on the operating system. Also provides means of spawning
  12 /// subprocess for commands. The design of this library is modeled after the
  13 /// proposed design of the Boost.Process library, and is design specifically to
  14 /// follow the style of standard libraries and potentially become a proposal
  15 /// for a standard library.
  16 ///
  17 /// This file declares the llvm::sys::Process class which contains a collection
  18 /// of legacy static interfaces for extracting various information about the
  19 /// current process. The goal is to migrate users of this API over to the new
  20 /// interfaces.
  21 ///
  22 //===----------------------------------------------------------------------===//
  23
  24 #ifndef LLVM_SUPPORT_PROCESS_H
  25 #define LLVM_SUPPORT_PROCESS_H
  26
  27 #include "llvm/ADT/Optional.h"
  28 #include "llvm/Support/Allocator.h"
  29 #include "llvm/Support/Chrono.h"
  30 #include "llvm/Support/DataTypes.h"
  31 #include <system_error>
  32
  33 namespace llvm {
  34 template <typename T> class ArrayRef;
  35 class StringRef;
  36
  37 namespace sys {
  38
  39
  40 /// A collection of legacy interfaces for querying information about the
  41 /// current executing process.
  42 class Process {
  43 public:
  44   static unsigned getPageSize();
  45
  46   /// Return process memory usage.
  47   /// This static function will return the total amount of memory allocated
  48   /// by the process. This only counts the memory allocated via the malloc,
  49   /// calloc and realloc functions and includes any "free" holes in the
  50   /// allocated space.
  51   static size_t GetMallocUsage();
  52
  53   /// This static function will set \p user_time to the amount of CPU time
  54   /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU
  55   /// time spent in system (kernel) mode.  If the operating system does not
  56   /// support collection of these metrics, a zero duration will be for both
  57   /// values.
  58   /// \param elapsed Returns the system_clock::now() giving current time
  59   /// \param user_time Returns the current amount of user time for the process
  60   /// \param sys_time Returns the current amount of system time for the process
  61   static void GetTimeUsage(TimePoint<> &elapsed,
  62                            std::chrono::nanoseconds &user_time,
  63                            std::chrono::nanoseconds &sys_time);
  64
  65   /// This function makes the necessary calls to the operating system to
  66   /// prevent core files or any other kind of large memory dumps that can
  67   /// occur when a program fails.
  68   /// Prevent core file generation.
  69   static void PreventCoreFiles();
  70
  71   /// true if PreventCoreFiles has been called, false otherwise.
  72   static bool AreCoreFilesPrevented();
  73
  74   // This function returns the environment variable \arg name's value as a UTF-8
  75   // string. \arg Name is assumed to be in UTF-8 encoding too.
  76   static Optional<std::string> GetEnv(StringRef name);
  77
  78   /// This function searches for an existing file in the list of directories
  79   /// in a PATH like environment variable, and returns the first file found,
  80   /// according to the order of the entries in the PATH like environment
  81   /// variable.  If an ignore list is specified, then any folder which is in
  82   /// the PATH like environment variable but is also in IgnoreList is not
  83   /// considered.
  84   static Optional<std::string> FindInEnvPath(StringRef EnvName,
  85                                              StringRef FileName,
  86                                              ArrayRef<std::string> IgnoreList);
  87
  88   static Optional<std::string> FindInEnvPath(StringRef EnvName,
  89                                              StringRef FileName);
  90
  91   // This functions ensures that the standard file descriptors (input, output,
  92   // and error) are properly mapped to a file descriptor before we use any of
  93   // them.  This should only be called by standalone programs, library
  94   // components should not call this.
  95   static std::error_code FixupStandardFileDescriptors();
  96
  97   // This function safely closes a file descriptor.  It is not safe to retry
  98   // close(2) when it returns with errno equivalent to EINTR; this is because
  99   // *nixen cannot agree if the file descriptor is, in fact, closed when this
 100   // occurs.
 101   //
 102   // N.B. Some operating systems, due to thread cancellation, cannot properly
 103   // guarantee that it will or will not be closed one way or the other!
 104   static std::error_code SafelyCloseFileDescriptor(int FD);
 105
 106   /// This function determines if the standard input is connected directly
 107   /// to a user's input (keyboard probably), rather than coming from a file
 108   /// or pipe.
 109   static bool StandardInIsUserInput();
 110
 111   /// This function determines if the standard output is connected to a
 112   /// "tty" or "console" window. That is, the output would be displayed to
 113   /// the user rather than being put on a pipe or stored in a file.
 114   static bool StandardOutIsDisplayed();
 115
 116   /// This function determines if the standard error is connected to a
 117   /// "tty" or "console" window. That is, the output would be displayed to
 118   /// the user rather than being put on a pipe or stored in a file.
 119   static bool StandardErrIsDisplayed();
 120
 121   /// This function determines if the given file descriptor is connected to
 122   /// a "tty" or "console" window. That is, the output would be displayed to
 123   /// the user rather than being put on a pipe or stored in a file.
 124   static bool FileDescriptorIsDisplayed(int fd);
 125
 126   /// This function determines if the given file descriptor is displayd and
 127   /// supports colors.
 128   static bool FileDescriptorHasColors(int fd);
 129
 130   /// This function determines the number of columns in the window
 131   /// if standard output is connected to a "tty" or "console"
 132   /// window. If standard output is not connected to a tty or
 133   /// console, or if the number of columns cannot be determined,
 134   /// this routine returns zero.
 135   static unsigned StandardOutColumns();
 136
 137   /// This function determines the number of columns in the window
 138   /// if standard error is connected to a "tty" or "console"
 139   /// window. If standard error is not connected to a tty or
 140   /// console, or if the number of columns cannot be determined,
 141   /// this routine returns zero.
 142   static unsigned StandardErrColumns();
 143
 144   /// This function determines whether the terminal connected to standard
 145   /// output supports colors. If standard output is not connected to a
 146   /// terminal, this function returns false.
 147   static bool StandardOutHasColors();
 148
 149   /// This function determines whether the terminal connected to standard
 150   /// error supports colors. If standard error is not connected to a
 151   /// terminal, this function returns false.
 152   static bool StandardErrHasColors();
 153
 154   /// Enables or disables whether ANSI escape sequences are used to output
 155   /// colors. This only has an effect on Windows.
 156   /// Note: Setting this option is not thread-safe and should only be done
 157   /// during initialization.
 158   static void UseANSIEscapeCodes(bool enable);
 159
 160   /// Whether changing colors requires the output to be flushed.
 161   /// This is needed on systems that don't support escape sequences for
 162   /// changing colors.
 163   static bool ColorNeedsFlush();
 164
 165   /// This function returns the colorcode escape sequences.
 166   /// If ColorNeedsFlush() is true then this function will change the colors
 167   /// and return an empty escape sequence. In that case it is the
 168   /// responsibility of the client to flush the output stream prior to
 169   /// calling this function.
 170   static const char *OutputColor(char c, bool bold, bool bg);
 171
 172   /// Same as OutputColor, but only enables the bold attribute.
 173   static const char *OutputBold(bool bg);
 174
 175   /// This function returns the escape sequence to reverse forground and
 176   /// background colors.
 177   static const char *OutputReverse();
 178
 179   /// Resets the terminals colors, or returns an escape sequence to do so.
 180   static const char *ResetColor();
 181
 182   /// Get the result of a process wide random number generator. The
 183   /// generator will be automatically seeded in non-deterministic fashion.
 184   static unsigned GetRandomNumber();
 185 };
 186
 187 }
 188 }
 189
 190 #endif