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
35namespace llvm {
36template <typename T> class ArrayRef;
37class StringRef;
38
39namespace sys {
40
41
42/// A collection of legacy interfaces for querying information about the
43/// current executing process.
44class Process {
45public:
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
221}
222}
223
224#endif
225