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

source code of llvm/include/llvm/Support/Process.h