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