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/AllocatorBase.h" 29 #include "llvm/Support/Chrono.h" 30 #include "llvm/Support/DataTypes.h" 31 #include "llvm/Support/Error.h" 32 #include "llvm/Support/Program.h" 33 #include <system_error> 34 35 namespace llvm { 36 template <typename T> class ArrayRef; 37 class StringRef; 38 39 namespace sys { 40 41 42 /// A collection of legacy interfaces for querying information about the 43 /// current executing process. 44 class Process { 45 public: 46 using Pid = int32_t; 47 48 /// Get the process's identifier. 49 static Pid getProcessId(); 50 51 /// Get the process's page size. 52 /// This may fail if the underlying syscall returns an error. In most cases, 53 /// page size information is used for optimization, and this error can be 54 /// safely discarded by calling consumeError, and an estimated page size 55 /// substituted instead. 56 static Expected<unsigned> getPageSize(); 57 58 /// Get the process's estimated page size. 59 /// This function always succeeds, but if the underlying syscall to determine 60 /// the page size fails then this will silently return an estimated page size. 61 /// The estimated page size is guaranteed to be a power of 2. 62 static unsigned getPageSizeEstimate() { 63 if (auto PageSize = getPageSize()) 64 return *PageSize; 65 else { 66 consumeError(PageSize.takeError()); 67 return 4096; 68 } 69 } 70 71 /// Return process memory usage. 72 /// This static function will return the total amount of memory allocated 73 /// by the process. This only counts the memory allocated via the malloc, 74 /// calloc and realloc functions and includes any "free" holes in the 75 /// allocated space. 76 static size_t GetMallocUsage(); 77 78 /// This static function will set \p user_time to the amount of CPU time 79 /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU 80 /// time spent in system (kernel) mode. If the operating system does not 81 /// support collection of these metrics, a zero duration will be for both 82 /// values. 83 /// \param elapsed Returns the system_clock::now() giving current time 84 /// \param user_time Returns the current amount of user time for the process 85 /// \param sys_time Returns the current amount of system time for the process 86 static void GetTimeUsage(TimePoint<> &elapsed, 87 std::chrono::nanoseconds &user_time, 88 std::chrono::nanoseconds &sys_time); 89 90 /// This function makes the necessary calls to the operating system to 91 /// prevent core files or any other kind of large memory dumps that can 92 /// occur when a program fails. 93 /// Prevent core file generation. 94 static void PreventCoreFiles(); 95 96 /// true if PreventCoreFiles has been called, false otherwise. 97 static bool AreCoreFilesPrevented(); 98 99 // This function returns the environment variable \arg name's value as a UTF-8 100 // string. \arg Name is assumed to be in UTF-8 encoding too. 101 static Optional<std::string> GetEnv(StringRef name); 102 103 /// This function searches for an existing file in the list of directories 104 /// in a PATH like environment variable, and returns the first file found, 105 /// according to the order of the entries in the PATH like environment 106 /// variable. If an ignore list is specified, then any folder which is in 107 /// the PATH like environment variable but is also in IgnoreList is not 108 /// considered. 109 static Optional<std::string> FindInEnvPath(StringRef EnvName, 110 StringRef FileName, 111 ArrayRef<std::string> IgnoreList, 112 char Separator = EnvPathSeparator); 113 114 static Optional<std::string> FindInEnvPath(StringRef EnvName, 115 StringRef FileName, 116 char Separator = EnvPathSeparator); 117 118 // This functions ensures that the standard file descriptors (input, output, 119 // and error) are properly mapped to a file descriptor before we use any of 120 // them. This should only be called by standalone programs, library 121 // components should not call this. 122 static std::error_code FixupStandardFileDescriptors(); 123 124 // This function safely closes a file descriptor. It is not safe to retry 125 // close(2) when it returns with errno equivalent to EINTR; this is because 126 // *nixen cannot agree if the file descriptor is, in fact, closed when this 127 // occurs. 128 // 129 // N.B. Some operating systems, due to thread cancellation, cannot properly 130 // guarantee that it will or will not be closed one way or the other! 131 static std::error_code SafelyCloseFileDescriptor(int FD); 132 133 /// This function determines if the standard input is connected directly 134 /// to a user's input (keyboard probably), rather than coming from a file 135 /// or pipe. 136 static bool StandardInIsUserInput(); 137 138 /// This function determines if the standard output is connected to a 139 /// "tty" or "console" window. That is, the output would be displayed to 140 /// the user rather than being put on a pipe or stored in a file. 141 static bool StandardOutIsDisplayed(); 142 143 /// This function determines if the standard error is connected to a 144 /// "tty" or "console" window. That is, the output would be displayed to 145 /// the user rather than being put on a pipe or stored in a file. 146 static bool StandardErrIsDisplayed(); 147 148 /// This function determines if the given file descriptor is connected to 149 /// a "tty" or "console" window. That is, the output would be displayed to 150 /// the user rather than being put on a pipe or stored in a file. 151 static bool FileDescriptorIsDisplayed(int fd); 152 153 /// This function determines if the given file descriptor is displayd and 154 /// supports colors. 155 static bool FileDescriptorHasColors(int fd); 156 157 /// This function determines the number of columns in the window 158 /// if standard output is connected to a "tty" or "console" 159 /// window. If standard output is not connected to a tty or 160 /// console, or if the number of columns cannot be determined, 161 /// this routine returns zero. 162 static unsigned StandardOutColumns(); 163 164 /// This function determines the number of columns in the window 165 /// if standard error is connected to a "tty" or "console" 166 /// window. If standard error is not connected to a tty or 167 /// console, or if the number of columns cannot be determined, 168 /// this routine returns zero. 169 static unsigned StandardErrColumns(); 170 171 /// This function determines whether the terminal connected to standard 172 /// output supports colors. If standard output is not connected to a 173 /// terminal, this function returns false. 174 static bool StandardOutHasColors(); 175 176 /// This function determines whether the terminal connected to standard 177 /// error supports colors. If standard error is not connected to a 178 /// terminal, this function returns false. 179 static bool StandardErrHasColors(); 180 181 /// Enables or disables whether ANSI escape sequences are used to output 182 /// colors. This only has an effect on Windows. 183 /// Note: Setting this option is not thread-safe and should only be done 184 /// during initialization. 185 static void UseANSIEscapeCodes(bool enable); 186 187 /// Whether changing colors requires the output to be flushed. 188 /// This is needed on systems that don't support escape sequences for 189 /// changing colors. 190 static bool ColorNeedsFlush(); 191 192 /// This function returns the colorcode escape sequences. 193 /// If ColorNeedsFlush() is true then this function will change the colors 194 /// and return an empty escape sequence. In that case it is the 195 /// responsibility of the client to flush the output stream prior to 196 /// calling this function. 197 static const char *OutputColor(char c, bool bold, bool bg); 198 199 /// Same as OutputColor, but only enables the bold attribute. 200 static const char *OutputBold(bool bg); 201 202 /// This function returns the escape sequence to reverse forground and 203 /// background colors. 204 static const char *OutputReverse(); 205 206 /// Resets the terminals colors, or returns an escape sequence to do so. 207 static const char *ResetColor(); 208 209 /// Get the result of a process wide random number generator. The 210 /// generator will be automatically seeded in non-deterministic fashion. 211 static unsigned GetRandomNumber(); 212 213 /// Equivalent to ::exit(), except when running inside a CrashRecoveryContext. 214 /// In that case, the control flow will resume after RunSafely(), like for a 215 /// crash, rather than exiting the current process. 216 /// Use \arg NoCleanup for calling _exit() instead of exit(). 217 LLVM_ATTRIBUTE_NORETURN 218 static void Exit(int RetCode, bool NoCleanup = false); 219 220 private: 221 LLVM_ATTRIBUTE_NORETURN 222 static void ExitNoCleanup(int RetCode); 223 }; 224 225 } 226 } 227 228 #endif 229