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Andrew Scull5e1ddfa2018-08-14 10:06:54 +01001//===- llvm/Support/Process.h -----------------------------------*- C++ -*-===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9/// \file
10///
11/// Provides a library for accessing information about this process and other
12/// processes on the operating system. Also provides means of spawning
13/// subprocess for commands. The design of this library is modeled after the
14/// proposed design of the Boost.Process library, and is design specifically to
15/// follow the style of standard libraries and potentially become a proposal
16/// for a standard library.
17///
18/// This file declares the llvm::sys::Process class which contains a collection
19/// of legacy static interfaces for extracting various information about the
20/// current process. The goal is to migrate users of this API over to the new
21/// interfaces.
22///
23//===----------------------------------------------------------------------===//
24
25#ifndef LLVM_SUPPORT_PROCESS_H
26#define LLVM_SUPPORT_PROCESS_H
27
28#include "llvm/ADT/Optional.h"
29#include "llvm/Config/llvm-config.h"
30#include "llvm/Support/Allocator.h"
31#include "llvm/Support/Chrono.h"
32#include "llvm/Support/DataTypes.h"
33#include <system_error>
34
35namespace llvm {
36template <typename T> class ArrayRef;
37class StringRef;
38
39namespace sys {
40
41
42/// \brief A collection of legacy interfaces for querying information about the
43/// current executing process.
44class Process {
45public:
46 static unsigned getPageSize();
47
48 /// \brief Return process memory usage.
49 /// This static function will return the total amount of memory allocated
50 /// by the process. This only counts the memory allocated via the malloc,
51 /// calloc and realloc functions and includes any "free" holes in the
52 /// allocated space.
53 static size_t GetMallocUsage();
54
55 /// This static function will set \p user_time to the amount of CPU time
56 /// spent in user (non-kernel) mode and \p sys_time to the amount of CPU
57 /// time spent in system (kernel) mode. If the operating system does not
58 /// support collection of these metrics, a zero duration will be for both
59 /// values.
60 /// \param elapsed Returns the system_clock::now() giving current time
61 /// \param user_time Returns the current amount of user time for the process
62 /// \param sys_time Returns the current amount of system time for the process
63 static void GetTimeUsage(TimePoint<> &elapsed,
64 std::chrono::nanoseconds &user_time,
65 std::chrono::nanoseconds &sys_time);
66
67 /// This function makes the necessary calls to the operating system to
68 /// prevent core files or any other kind of large memory dumps that can
69 /// occur when a program fails.
70 /// @brief Prevent core file generation.
71 static void PreventCoreFiles();
72
73 /// \brief true if PreventCoreFiles has been called, false otherwise.
74 static bool AreCoreFilesPrevented();
75
76 // This function returns the environment variable \arg name's value as a UTF-8
77 // string. \arg Name is assumed to be in UTF-8 encoding too.
78 static Optional<std::string> GetEnv(StringRef name);
79
80 /// This function searches for an existing file in the list of directories
81 /// in a PATH like environment variable, and returns the first file found,
82 /// according to the order of the entries in the PATH like environment
83 /// variable. If an ignore list is specified, then any folder which is in
84 /// the PATH like environment variable but is also in IgnoreList is not
85 /// considered.
86 static Optional<std::string> FindInEnvPath(StringRef EnvName,
87 StringRef FileName,
88 ArrayRef<std::string> IgnoreList);
89
90 static Optional<std::string> FindInEnvPath(StringRef EnvName,
91 StringRef FileName);
92
93 /// This function returns a SmallVector containing the arguments passed from
94 /// the operating system to the program. This function expects to be handed
95 /// the vector passed in from main.
96 static std::error_code
97 GetArgumentVector(SmallVectorImpl<const char *> &Args,
98 ArrayRef<const char *> ArgsFromMain,
99 SpecificBumpPtrAllocator<char> &ArgAllocator);
100
101 // This functions ensures that the standard file descriptors (input, output,
102 // and error) are properly mapped to a file descriptor before we use any of
103 // them. This should only be called by standalone programs, library
104 // components should not call this.
105 static std::error_code FixupStandardFileDescriptors();
106
107 // This function safely closes a file descriptor. It is not safe to retry
108 // close(2) when it returns with errno equivalent to EINTR; this is because
109 // *nixen cannot agree if the file descriptor is, in fact, closed when this
110 // occurs.
111 //
112 // N.B. Some operating systems, due to thread cancellation, cannot properly
113 // guarantee that it will or will not be closed one way or the other!
114 static std::error_code SafelyCloseFileDescriptor(int FD);
115
116 /// This function determines if the standard input is connected directly
117 /// to a user's input (keyboard probably), rather than coming from a file
118 /// or pipe.
119 static bool StandardInIsUserInput();
120
121 /// This function determines if the standard output is connected to a
122 /// "tty" or "console" window. That is, the output would be displayed to
123 /// the user rather than being put on a pipe or stored in a file.
124 static bool StandardOutIsDisplayed();
125
126 /// This function determines if the standard error is connected to a
127 /// "tty" or "console" window. That is, the output would be displayed to
128 /// the user rather than being put on a pipe or stored in a file.
129 static bool StandardErrIsDisplayed();
130
131 /// This function determines if the given file descriptor is connected to
132 /// a "tty" or "console" window. That is, the output would be displayed to
133 /// the user rather than being put on a pipe or stored in a file.
134 static bool FileDescriptorIsDisplayed(int fd);
135
136 /// This function determines if the given file descriptor is displayd and
137 /// supports colors.
138 static bool FileDescriptorHasColors(int fd);
139
140 /// This function determines the number of columns in the window
141 /// if standard output is connected to a "tty" or "console"
142 /// window. If standard output is not connected to a tty or
143 /// console, or if the number of columns cannot be determined,
144 /// this routine returns zero.
145 static unsigned StandardOutColumns();
146
147 /// This function determines the number of columns in the window
148 /// if standard error is connected to a "tty" or "console"
149 /// window. If standard error is not connected to a tty or
150 /// console, or if the number of columns cannot be determined,
151 /// this routine returns zero.
152 static unsigned StandardErrColumns();
153
154 /// This function determines whether the terminal connected to standard
155 /// output supports colors. If standard output is not connected to a
156 /// terminal, this function returns false.
157 static bool StandardOutHasColors();
158
159 /// This function determines whether the terminal connected to standard
160 /// error supports colors. If standard error is not connected to a
161 /// terminal, this function returns false.
162 static bool StandardErrHasColors();
163
164 /// Enables or disables whether ANSI escape sequences are used to output
165 /// colors. This only has an effect on Windows.
166 /// Note: Setting this option is not thread-safe and should only be done
167 /// during initialization.
168 static void UseANSIEscapeCodes(bool enable);
169
170 /// Whether changing colors requires the output to be flushed.
171 /// This is needed on systems that don't support escape sequences for
172 /// changing colors.
173 static bool ColorNeedsFlush();
174
175 /// This function returns the colorcode escape sequences.
176 /// If ColorNeedsFlush() is true then this function will change the colors
177 /// and return an empty escape sequence. In that case it is the
178 /// responsibility of the client to flush the output stream prior to
179 /// calling this function.
180 static const char *OutputColor(char c, bool bold, bool bg);
181
182 /// Same as OutputColor, but only enables the bold attribute.
183 static const char *OutputBold(bool bg);
184
185 /// This function returns the escape sequence to reverse forground and
186 /// background colors.
187 static const char *OutputReverse();
188
189 /// Resets the terminals colors, or returns an escape sequence to do so.
190 static const char *ResetColor();
191
192 /// Get the result of a process wide random number generator. The
193 /// generator will be automatically seeded in non-deterministic fashion.
194 static unsigned GetRandomNumber();
195};
196
197}
198}
199
200#endif