LLVM  10.0.0svn
Process.h
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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 
34 namespace llvm {
35 template <typename T> class ArrayRef;
36 class StringRef;
37 
38 namespace sys {
39 
40 
41 /// A collection of legacy interfaces for querying information about the
42 /// current executing process.
43 class Process {
44 public:
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.
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.
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.
104  StringRef FileName,
105  ArrayRef<std::string> IgnoreList);
106 
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 
206 }
207 }
208 
209 #endif
This class represents lattice values for constants.
Definition: AllocatorList.h:23
static const char * ResetColor()
Resets the terminals colors, or returns an escape sequence to do so.
static const char * OutputColor(char c, bool bold, bool bg)
This function returns the colorcode escape sequences.
static bool StandardErrHasColors()
This function determines whether the terminal connected to standard error supports colors...
static bool FileDescriptorHasColors(int fd)
This function determines if the given file descriptor is displayd and supports colors.
static bool AreCoreFilesPrevented()
true if PreventCoreFiles has been called, false otherwise.
Definition: Process.cpp:89
static bool FileDescriptorIsDisplayed(int fd)
This function determines if the given file descriptor is connected to a "tty" or "console" window...
This file defines the MallocAllocator and BumpPtrAllocator interfaces.
static std::error_code FixupStandardFileDescriptors()
static bool ColorNeedsFlush()
Whether changing colors requires the output to be flushed.
static const char * OutputReverse()
This function returns the escape sequence to reverse forground and background colors.
Tagged union holding either a T or a Error.
Definition: yaml2obj.h:21
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
static unsigned getPageSizeEstimate()
Get the process&#39;s estimated page size.
Definition: Process.h:56
static bool StandardInIsUserInput()
This function determines if the standard input is connected directly to a user&#39;s input (keyboard prob...
static bool StandardOutIsDisplayed()
This function determines if the standard output is connected to a "tty" or "console" window...
static void UseANSIEscapeCodes(bool enable)
Enables or disables whether ANSI escape sequences are used to output colors.
static unsigned StandardOutColumns()
This function determines the number of columns in the window if standard output is connected to a "tt...
static Optional< std::string > FindInEnvPath(StringRef EnvName, StringRef FileName, ArrayRef< std::string > IgnoreList)
This function searches for an existing file in the list of directories in a PATH like environment var...
Definition: Process.cpp:35
void consumeError(Error Err)
Consume a Error without doing anything.
Definition: Error.h:981
static size_t GetMallocUsage()
Return process memory usage.
static bool StandardErrIsDisplayed()
This function determines if the standard error is connected to a "tty" or "console" window...
static void PreventCoreFiles()
This function makes the necessary calls to the operating system to prevent core files or any other ki...
static unsigned StandardErrColumns()
This function determines the number of columns in the window if standard error is connected to a "tty...
static bool StandardOutHasColors()
This function determines whether the terminal connected to standard output supports colors...
A collection of legacy interfaces for querying information about the current executing process...
Definition: Process.h:43
static unsigned GetRandomNumber()
Get the result of a process wide random number generator.
static void GetTimeUsage(TimePoint<> &elapsed, std::chrono::nanoseconds &user_time, std::chrono::nanoseconds &sys_time)
This static function will set user_time to the amount of CPU time spent in user (non-kernel) mode and...
static cl::opt< int > PageSize("imp-null-check-page-size", cl::desc("The page size of the target in bytes"), cl::init(4096), cl::Hidden)
static const char * OutputBold(bool bg)
Same as OutputColor, but only enables the bold attribute.
static const char * name
static Expected< unsigned > getPageSize()
Get the process&#39;s page size.
static std::error_code SafelyCloseFileDescriptor(int FD)
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
static Optional< std::string > GetEnv(StringRef name)
std::chrono::time_point< std::chrono::system_clock, D > TimePoint
A time point on the system clock.
Definition: Chrono.h:33