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