1//===- Unix/Process.cpp - Unix Process Implementation --------- -*- 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//
9// This file provides the generic Unix implementation of the Process class.
10//
11//===----------------------------------------------------------------------===//
12
13#include "Unix.h"
14#include "llvm/ADT/Hashing.h"
15#include "llvm/ADT/StringRef.h"
16#include "llvm/Config/config.h"
17#include <mutex>
18#include <optional>
19#if HAVE_FCNTL_H
20#include <fcntl.h>
21#endif
22#ifdef HAVE_SYS_TIME_H
23#include <sys/time.h>
24#endif
25#ifdef HAVE_SYS_RESOURCE_H
26#include <sys/resource.h>
27#endif
28#ifdef HAVE_SYS_STAT_H
29#include <sys/stat.h>
30#endif
31#if HAVE_SIGNAL_H
32#include <signal.h>
33#endif
34#if defined(HAVE_MALLINFO) || defined(HAVE_MALLINFO2)
35#include <malloc.h>
36#endif
37#if defined(HAVE_MALLCTL)
38#include <malloc_np.h>
39#endif
40#ifdef HAVE_MALLOC_MALLOC_H
41#include <malloc/malloc.h>
42#endif
43#ifdef HAVE_SYS_IOCTL_H
44#include <sys/ioctl.h>
45#endif
46#ifdef HAVE_TERMIOS_H
47#include <termios.h>
48#endif
49
50//===----------------------------------------------------------------------===//
51//=== WARNING: Implementation here must contain only generic UNIX code that
52//=== is guaranteed to work on *all* UNIX variants.
53//===----------------------------------------------------------------------===//
54
55using namespace llvm;
56using namespace sys;
57
58static std::pair<std::chrono::microseconds, std::chrono::microseconds>
59getRUsageTimes() {
60#if defined(HAVE_GETRUSAGE)
61 struct rusage RU;
62 ::getrusage(RUSAGE_SELF, usage: &RU);
63 return {toDuration(TV: RU.ru_utime), toDuration(TV: RU.ru_stime)};
64#else
65#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
66#warning Cannot get usage times on this platform
67#endif
68 return {std::chrono::microseconds::zero(), std::chrono::microseconds::zero()};
69#endif
70}
71
72Process::Pid Process::getProcessId() {
73 static_assert(sizeof(Pid) >= sizeof(pid_t),
74 "Process::Pid should be big enough to store pid_t");
75 return Pid(::getpid());
76}
77
78// On Cygwin, getpagesize() returns 64k(AllocationGranularity) and
79// offset in mmap(3) should be aligned to the AllocationGranularity.
80Expected<unsigned> Process::getPageSize() {
81#if defined(HAVE_GETPAGESIZE)
82 static const int page_size = ::getpagesize();
83#elif defined(HAVE_SYSCONF)
84 static long page_size = ::sysconf(_SC_PAGE_SIZE);
85#else
86#error Cannot get the page size on this machine
87#endif
88 if (page_size == -1)
89 return errorCodeToError(EC: errnoAsErrorCode());
90
91 return static_cast<unsigned>(page_size);
92}
93
94size_t Process::GetMallocUsage() {
95#if defined(HAVE_MALLINFO2)
96 struct mallinfo2 mi;
97 mi = ::mallinfo2();
98 return mi.uordblks;
99#elif defined(HAVE_MALLINFO)
100 struct mallinfo mi;
101 mi = ::mallinfo();
102 return mi.uordblks;
103#elif defined(HAVE_MALLOC_ZONE_STATISTICS) && defined(HAVE_MALLOC_MALLOC_H)
104 malloc_statistics_t Stats;
105 malloc_zone_statistics(malloc_default_zone(), &Stats);
106 return Stats.size_in_use; // darwin
107#elif defined(HAVE_MALLCTL)
108 size_t alloc, sz;
109 sz = sizeof(size_t);
110 if (mallctl("stats.allocated", &alloc, &sz, NULL, 0) == 0)
111 return alloc;
112 return 0;
113#elif defined(HAVE_SBRK)
114 // Note this is only an approximation and more closely resembles
115 // the value returned by mallinfo in the arena field.
116 static char *StartOfMemory = reinterpret_cast<char *>(::sbrk(0));
117 char *EndOfMemory = (char *)sbrk(0);
118 if (EndOfMemory != ((char *)-1) && StartOfMemory != ((char *)-1))
119 return EndOfMemory - StartOfMemory;
120 return 0;
121#else
122#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
123#warning Cannot get malloc info on this platform
124#endif
125 return 0;
126#endif
127}
128
129void Process::GetTimeUsage(TimePoint<> &elapsed,
130 std::chrono::nanoseconds &user_time,
131 std::chrono::nanoseconds &sys_time) {
132 elapsed = std::chrono::system_clock::now();
133 std::tie(args&: user_time, args&: sys_time) = getRUsageTimes();
134}
135
136#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)
137#include <mach/mach.h>
138#endif
139
140// Some LLVM programs such as bugpoint produce core files as a normal part of
141// their operation. To prevent the disk from filling up, this function
142// does what's necessary to prevent their generation.
143void Process::PreventCoreFiles() {
144#if HAVE_SETRLIMIT
145 struct rlimit rlim;
146 getrlimit(RLIMIT_CORE, rlimits: &rlim);
147#ifdef __linux__
148 // On Linux, if the kernel.core_pattern sysctl starts with a '|' (i.e. it
149 // is being piped to a coredump handler such as systemd-coredumpd), the
150 // kernel ignores RLIMIT_CORE (since we aren't creating a file in the file
151 // system) except for the magic value of 1, which disables coredumps when
152 // piping. 1 byte is too small for any kind of valid core dump, so it
153 // also disables coredumps if kernel.core_pattern creates files directly.
154 // While most piped coredump handlers do respect the crashing processes'
155 // RLIMIT_CORE, this is notable not the case for Debian's systemd-coredump
156 // due to a local patch that changes sysctl.d/50-coredump.conf to ignore
157 // the specified limit and instead use RLIM_INFINITY.
158 //
159 // The alternative to using RLIMIT_CORE=1 would be to use prctl() with the
160 // PR_SET_DUMPABLE flag, however that also prevents ptrace(), so makes it
161 // impossible to attach a debugger.
162 rlim.rlim_cur = std::min<rlim_t>(a: 1, b: rlim.rlim_max);
163#else
164 rlim.rlim_cur = 0;
165#endif
166 setrlimit(RLIMIT_CORE, rlimits: &rlim);
167#endif
168
169#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)
170 // Disable crash reporting on Mac OS X 10.0-10.4
171
172 // get information about the original set of exception ports for the task
173 mach_msg_type_number_t Count = 0;
174 exception_mask_t OriginalMasks[EXC_TYPES_COUNT];
175 exception_port_t OriginalPorts[EXC_TYPES_COUNT];
176 exception_behavior_t OriginalBehaviors[EXC_TYPES_COUNT];
177 thread_state_flavor_t OriginalFlavors[EXC_TYPES_COUNT];
178 kern_return_t err = task_get_exception_ports(
179 mach_task_self(), EXC_MASK_ALL, OriginalMasks, &Count, OriginalPorts,
180 OriginalBehaviors, OriginalFlavors);
181 if (err == KERN_SUCCESS) {
182 // replace each with MACH_PORT_NULL.
183 for (unsigned i = 0; i != Count; ++i)
184 task_set_exception_ports(mach_task_self(), OriginalMasks[i],
185 MACH_PORT_NULL, OriginalBehaviors[i],
186 OriginalFlavors[i]);
187 }
188
189 // Disable crash reporting on Mac OS X 10.5
190 signal(SIGABRT, _exit);
191 signal(SIGILL, _exit);
192 signal(SIGFPE, _exit);
193 signal(SIGSEGV, _exit);
194 signal(SIGBUS, _exit);
195#endif
196
197 coreFilesPrevented = true;
198}
199
200std::optional<std::string> Process::GetEnv(StringRef Name) {
201 std::string NameStr = Name.str();
202 const char *Val = ::getenv(name: NameStr.c_str());
203 if (!Val)
204 return std::nullopt;
205 return std::string(Val);
206}
207
208namespace {
209class FDCloser {
210public:
211 FDCloser(int &FD) : FD(FD), KeepOpen(false) {}
212 void keepOpen() { KeepOpen = true; }
213 ~FDCloser() {
214 if (!KeepOpen && FD >= 0)
215 ::close(fd: FD);
216 }
217
218private:
219 FDCloser(const FDCloser &) = delete;
220 void operator=(const FDCloser &) = delete;
221
222 int &FD;
223 bool KeepOpen;
224};
225} // namespace
226
227std::error_code Process::FixupStandardFileDescriptors() {
228 int NullFD = -1;
229 FDCloser FDC(NullFD);
230 const int StandardFDs[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};
231 for (int StandardFD : StandardFDs) {
232 struct stat st;
233 errno = 0;
234 if (RetryAfterSignal(Fail: -1, F&: ::fstat, As: StandardFD, As: &st) < 0) {
235 assert(errno && "expected errno to be set if fstat failed!");
236 // fstat should return EBADF if the file descriptor is closed.
237 if (errno != EBADF)
238 return errnoAsErrorCode();
239 }
240 // if fstat succeeds, move on to the next FD.
241 if (!errno)
242 continue;
243 assert(errno == EBADF && "expected errno to have EBADF at this point!");
244
245 if (NullFD < 0) {
246 // Call ::open in a lambda to avoid overload resolution in
247 // RetryAfterSignal when open is overloaded, such as in Bionic.
248 auto Open = [&]() { return ::open(file: "/dev/null", O_RDWR); };
249 if ((NullFD = RetryAfterSignal(Fail: -1, F: Open)) < 0)
250 return errnoAsErrorCode();
251 }
252
253 if (NullFD == StandardFD)
254 FDC.keepOpen();
255 else if (dup2(fd: NullFD, fd2: StandardFD) < 0)
256 return errnoAsErrorCode();
257 }
258 return std::error_code();
259}
260
261std::error_code Process::SafelyCloseFileDescriptor(int FD) {
262 // Create a signal set filled with *all* signals.
263 sigset_t FullSet, SavedSet;
264 if (sigfillset(set: &FullSet) < 0 || sigfillset(set: &SavedSet) < 0)
265 return errnoAsErrorCode();
266
267 // Atomically swap our current signal mask with a full mask.
268#if LLVM_ENABLE_THREADS
269 if (int EC = pthread_sigmask(SIG_SETMASK, newmask: &FullSet, oldmask: &SavedSet))
270 return std::error_code(EC, std::generic_category());
271#else
272 if (sigprocmask(SIG_SETMASK, &FullSet, &SavedSet) < 0)
273 return errnoAsErrorCode();
274#endif
275 // Attempt to close the file descriptor.
276 // We need to save the error, if one occurs, because our subsequent call to
277 // pthread_sigmask might tamper with errno.
278 int ErrnoFromClose = 0;
279 if (::close(fd: FD) < 0)
280 ErrnoFromClose = errno;
281 // Restore the signal mask back to what we saved earlier.
282 int EC = 0;
283#if LLVM_ENABLE_THREADS
284 EC = pthread_sigmask(SIG_SETMASK, newmask: &SavedSet, oldmask: nullptr);
285#else
286 if (sigprocmask(SIG_SETMASK, &SavedSet, nullptr) < 0)
287 EC = errno;
288#endif
289 // The error code from close takes precedence over the one from
290 // pthread_sigmask.
291 if (ErrnoFromClose)
292 return std::error_code(ErrnoFromClose, std::generic_category());
293 return std::error_code(EC, std::generic_category());
294}
295
296bool Process::StandardInIsUserInput() {
297 return FileDescriptorIsDisplayed(STDIN_FILENO);
298}
299
300bool Process::StandardOutIsDisplayed() {
301 return FileDescriptorIsDisplayed(STDOUT_FILENO);
302}
303
304bool Process::StandardErrIsDisplayed() {
305 return FileDescriptorIsDisplayed(STDERR_FILENO);
306}
307
308bool Process::FileDescriptorIsDisplayed(int fd) {
309#if HAVE_ISATTY
310 return isatty(fd: fd);
311#else
312 // If we don't have isatty, just return false.
313 return false;
314#endif
315}
316
317static unsigned getColumns() {
318 // If COLUMNS is defined in the environment, wrap to that many columns.
319 if (const char *ColumnsStr = std::getenv(name: "COLUMNS")) {
320 int Columns = std::atoi(nptr: ColumnsStr);
321 if (Columns > 0)
322 return Columns;
323 }
324
325 // We used to call ioctl TIOCGWINSZ to determine the width. It is considered
326 // unuseful.
327 return 0;
328}
329
330unsigned Process::StandardOutColumns() {
331 if (!StandardOutIsDisplayed())
332 return 0;
333
334 return getColumns();
335}
336
337unsigned Process::StandardErrColumns() {
338 if (!StandardErrIsDisplayed())
339 return 0;
340
341 return getColumns();
342}
343
344static bool terminalHasColors() {
345 // Check if the current terminal is one of terminals that are known to support
346 // ANSI color escape codes.
347 if (const char *TermStr = std::getenv(name: "TERM")) {
348 return StringSwitch<bool>(TermStr)
349 .Case(S: "ansi", Value: true)
350 .Case(S: "cygwin", Value: true)
351 .Case(S: "linux", Value: true)
352 .StartsWith(S: "screen", Value: true)
353 .StartsWith(S: "xterm", Value: true)
354 .StartsWith(S: "vt100", Value: true)
355 .StartsWith(S: "rxvt", Value: true)
356 .EndsWith(S: "color", Value: true)
357 .Default(Value: false);
358 }
359
360 return false;
361}
362
363bool Process::FileDescriptorHasColors(int fd) {
364 // A file descriptor has colors if it is displayed and the terminal has
365 // colors.
366 return FileDescriptorIsDisplayed(fd) && terminalHasColors();
367}
368
369bool Process::StandardOutHasColors() {
370 return FileDescriptorHasColors(STDOUT_FILENO);
371}
372
373bool Process::StandardErrHasColors() {
374 return FileDescriptorHasColors(STDERR_FILENO);
375}
376
377void Process::UseANSIEscapeCodes(bool /*enable*/) {
378 // No effect.
379}
380
381bool Process::ColorNeedsFlush() {
382 // No, we use ANSI escape sequences.
383 return false;
384}
385
386const char *Process::OutputColor(char code, bool bold, bool bg) {
387 return colorcodes[bg ? 1 : 0][bold ? 1 : 0][code & 15];
388}
389
390const char *Process::OutputBold(bool bg) { return "\033[1m"; }
391
392const char *Process::OutputReverse() { return "\033[7m"; }
393
394const char *Process::ResetColor() { return "\033[0m"; }
395
396#if !HAVE_DECL_ARC4RANDOM
397static unsigned GetRandomNumberSeed() {
398 // Attempt to get the initial seed from /dev/urandom, if possible.
399 int urandomFD = open(file: "/dev/urandom", O_RDONLY);
400
401 if (urandomFD != -1) {
402 unsigned seed;
403 // Don't use a buffered read to avoid reading more data
404 // from /dev/urandom than we need.
405 int count = read(fd: urandomFD, buf: (void *)&seed, nbytes: sizeof(seed));
406
407 close(fd: urandomFD);
408
409 // Return the seed if the read was successful.
410 if (count == sizeof(seed))
411 return seed;
412 }
413
414 // Otherwise, swizzle the current time and the process ID to form a reasonable
415 // seed.
416 const auto Now = std::chrono::high_resolution_clock::now();
417 return hash_combine(args: Now.time_since_epoch().count(), args: ::getpid());
418}
419#endif
420
421unsigned llvm::sys::Process::GetRandomNumber() {
422#if HAVE_DECL_ARC4RANDOM
423 return arc4random();
424#else
425 static int x = (static_cast<void>(::srand(seed: GetRandomNumberSeed())), 0);
426 (void)x;
427 return ::rand();
428#endif
429}
430
431[[noreturn]] void Process::ExitNoCleanup(int RetCode) { _Exit(status: RetCode); }
432