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
220private:
221  LLVM_ATTRIBUTE_NORETURN
222  static void ExitNoCleanup(int RetCode);
223};
224
225}
226}
227
228#endif
229