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 "llvm/Config/llvm-config.h" // for LLVM_ENABLE_THREADS
18#include <mutex>
19#include <optional>
20#include <fcntl.h>
21#include <sys/time.h>
22#include <sys/resource.h>
23#include <sys/stat.h>
24#include <signal.h>
25#if defined(HAVE_MALLINFO) || defined(HAVE_MALLINFO2)
26#include <malloc.h>
27#endif
28#if defined(HAVE_MALLCTL)
29#include <malloc_np.h>
30#endif
31#ifdef HAVE_MALLOC_MALLOC_H
32#include <malloc/malloc.h>
33#endif
34#ifdef HAVE_GETAUXVAL
35#include <sys/auxv.h>
36#endif
37#ifdef HAVE_SYS_IOCTL_H
38#include <sys/ioctl.h>
39#endif
40
41//===----------------------------------------------------------------------===//
42//=== WARNING: Implementation here must contain only generic UNIX code that
43//=== is guaranteed to work on *all* UNIX variants.
44//===----------------------------------------------------------------------===//
45
46using namespace llvm;
47using namespace sys;
48
49static std::pair<std::chrono::microseconds, std::chrono::microseconds>
50getRUsageTimes() {
51#if defined(HAVE_GETRUSAGE)
52 struct rusage RU;
53 ::getrusage(RUSAGE_SELF, usage: &RU);
54 return {toDuration(TV: RU.ru_utime), toDuration(TV: RU.ru_stime)};
55#else
56#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
57#warning Cannot get usage times on this platform
58#endif
59 return {std::chrono::microseconds::zero(), std::chrono::microseconds::zero()};
60#endif
61}
62
63Process::Pid Process::getProcessId() {
64 static_assert(sizeof(Pid) >= sizeof(pid_t),
65 "Process::Pid should be big enough to store pid_t");
66 return Pid(::getpid());
67}
68
69// On Cygwin, getpagesize() returns 64k(AllocationGranularity) and
70// offset in mmap(3) should be aligned to the AllocationGranularity.
71Expected<unsigned> Process::getPageSize() {
72#if defined(HAVE_GETAUXVAL)
73 static const int page_size = ::getauxval(AT_PAGESZ);
74#elif defined(HAVE_GETPAGESIZE)
75 static const int page_size = ::getpagesize();
76#elif defined(HAVE_SYSCONF)
77 static long page_size = ::sysconf(_SC_PAGE_SIZE);
78#else
79#error Cannot get the page size on this machine
80#endif
81 if (page_size == -1)
82 return errorCodeToError(EC: errnoAsErrorCode());
83
84 assert(page_size > 0 && "Page size cannot be 0");
85 assert((page_size % 1024) == 0 && "Page size must be aligned by 1024");
86 return static_cast<unsigned>(page_size);
87}
88
89size_t Process::GetMallocUsage() {
90#if defined(HAVE_MALLINFO2)
91 struct mallinfo2 mi;
92 mi = ::mallinfo2();
93 return mi.uordblks;
94#elif defined(HAVE_MALLINFO)
95 struct mallinfo mi;
96 mi = ::mallinfo();
97 return mi.uordblks;
98#elif defined(HAVE_MALLOC_ZONE_STATISTICS) && defined(HAVE_MALLOC_MALLOC_H)
99 malloc_statistics_t Stats;
100 malloc_zone_statistics(malloc_default_zone(), &Stats);
101 return Stats.size_in_use; // darwin
102#elif defined(HAVE_MALLCTL)
103 size_t alloc, sz;
104 sz = sizeof(size_t);
105 if (mallctl("stats.allocated", &alloc, &sz, NULL, 0) == 0)
106 return alloc;
107 return 0;
108#elif defined(HAVE_SBRK)
109 // Note this is only an approximation and more closely resembles
110 // the value returned by mallinfo in the arena field.
111 static char *StartOfMemory = reinterpret_cast<char *>(::sbrk(0));
112 char *EndOfMemory = (char *)sbrk(0);
113 if (EndOfMemory != ((char *)-1) && StartOfMemory != ((char *)-1))
114 return EndOfMemory - StartOfMemory;
115 return 0;
116#else
117#ifndef __MVS__ // Exclude for MVS in case -pedantic is used
118#warning Cannot get malloc info on this platform
119#endif
120 return 0;
121#endif
122}
123
124void Process::GetTimeUsage(TimePoint<> &elapsed,
125 std::chrono::nanoseconds &user_time,
126 std::chrono::nanoseconds &sys_time) {
127 elapsed = std::chrono::system_clock::now();
128 std::tie(args&: user_time, args&: sys_time) = getRUsageTimes();
129}
130
131#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)
132#include <mach/mach.h>
133#endif
134
135// Some LLVM programs such as bugpoint produce core files as a normal part of
136// their operation. To prevent the disk from filling up, this function
137// does what's necessary to prevent their generation.
138void Process::PreventCoreFiles() {
139 struct rlimit rlim;
140 getrlimit(RLIMIT_CORE, rlimits: &rlim);
141#ifdef __linux__
142 // On Linux, if the kernel.core_pattern sysctl starts with a '|' (i.e. it
143 // is being piped to a coredump handler such as systemd-coredumpd), the
144 // kernel ignores RLIMIT_CORE (since we aren't creating a file in the file
145 // system) except for the magic value of 1, which disables coredumps when
146 // piping. 1 byte is too small for any kind of valid core dump, so it
147 // also disables coredumps if kernel.core_pattern creates files directly.
148 // While most piped coredump handlers do respect the crashing processes'
149 // RLIMIT_CORE, this is notable not the case for Debian's systemd-coredump
150 // due to a local patch that changes sysctl.d/50-coredump.conf to ignore
151 // the specified limit and instead use RLIM_INFINITY.
152 //
153 // The alternative to using RLIMIT_CORE=1 would be to use prctl() with the
154 // PR_SET_DUMPABLE flag, however that also prevents ptrace(), so makes it
155 // impossible to attach a debugger.
156 rlim.rlim_cur = std::min<rlim_t>(a: 1, b: rlim.rlim_max);
157#else
158 rlim.rlim_cur = 0;
159#endif
160 setrlimit(RLIMIT_CORE, rlimits: &rlim);
161
162#if defined(HAVE_MACH_MACH_H) && !defined(__GNU__)
163 // Disable crash reporting on Mac OS X 10.0-10.4
164
165 // get information about the original set of exception ports for the task
166 mach_msg_type_number_t Count = 0;
167 exception_mask_t OriginalMasks[EXC_TYPES_COUNT];
168 exception_port_t OriginalPorts[EXC_TYPES_COUNT];
169 exception_behavior_t OriginalBehaviors[EXC_TYPES_COUNT];
170 thread_state_flavor_t OriginalFlavors[EXC_TYPES_COUNT];
171 kern_return_t err = task_get_exception_ports(
172 mach_task_self(), EXC_MASK_ALL, OriginalMasks, &Count, OriginalPorts,
173 OriginalBehaviors, OriginalFlavors);
174 if (err == KERN_SUCCESS) {
175 // replace each with MACH_PORT_NULL.
176 for (unsigned i = 0; i != Count; ++i)
177 task_set_exception_ports(mach_task_self(), OriginalMasks[i],
178 MACH_PORT_NULL, OriginalBehaviors[i],
179 OriginalFlavors[i]);
180 }
181
182 // Disable crash reporting on Mac OS X 10.5
183 signal(SIGABRT, _exit);
184 signal(SIGILL, _exit);
185 signal(SIGFPE, _exit);
186 signal(SIGSEGV, _exit);
187 signal(SIGBUS, _exit);
188#endif
189
190 coreFilesPrevented = true;
191}
192
193std::optional<std::string> Process::GetEnv(StringRef Name) {
194 std::string NameStr = Name.str();
195 const char *Val = ::getenv(name: NameStr.c_str());
196 if (!Val)
197 return std::nullopt;
198 return std::string(Val);
199}
200
201namespace {
202class FDCloser {
203public:
204 FDCloser(int &FD) : FD(FD), KeepOpen(false) {}
205 void keepOpen() { KeepOpen = true; }
206 ~FDCloser() {
207 if (!KeepOpen && FD >= 0)
208 ::close(fd: FD);
209 }
210
211private:
212 FDCloser(const FDCloser &) = delete;
213 void operator=(const FDCloser &) = delete;
214
215 int &FD;
216 bool KeepOpen;
217};
218} // namespace
219
220std::error_code Process::FixupStandardFileDescriptors() {
221 int NullFD = -1;
222 FDCloser FDC(NullFD);
223 const int StandardFDs[] = {STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO};
224 for (int StandardFD : StandardFDs) {
225 struct stat st;
226 errno = 0;
227 if (RetryAfterSignal(Fail: -1, F&: ::fstat, As: StandardFD, As: &st) < 0) {
228 assert(errno && "expected errno to be set if fstat failed!");
229 // fstat should return EBADF if the file descriptor is closed.
230 if (errno != EBADF)
231 return errnoAsErrorCode();
232 }
233 // if fstat succeeds, move on to the next FD.
234 if (!errno)
235 continue;
236 assert(errno == EBADF && "expected errno to have EBADF at this point!");
237
238 if (NullFD < 0) {
239 // Call ::open in a lambda to avoid overload resolution in
240 // RetryAfterSignal when open is overloaded, such as in Bionic.
241 auto Open = [&]() { return ::open(file: "/dev/null", O_RDWR); };
242 if ((NullFD = RetryAfterSignal(Fail: -1, F: Open)) < 0)
243 return errnoAsErrorCode();
244 }
245
246 if (NullFD == StandardFD)
247 FDC.keepOpen();
248 else if (dup2(fd: NullFD, fd2: StandardFD) < 0)
249 return errnoAsErrorCode();
250 }
251 return std::error_code();
252}
253
254std::error_code Process::SafelyCloseFileDescriptor(int FD) {
255 // Create a signal set filled with *all* signals.
256 sigset_t FullSet, SavedSet;
257 if (sigfillset(set: &FullSet) < 0 || sigfillset(set: &SavedSet) < 0)
258 return errnoAsErrorCode();
259
260 // Atomically swap our current signal mask with a full mask.
261#if LLVM_ENABLE_THREADS
262 if (int EC = pthread_sigmask(SIG_SETMASK, newmask: &FullSet, oldmask: &SavedSet))
263 return std::error_code(EC, std::generic_category());
264#else
265 if (sigprocmask(SIG_SETMASK, &FullSet, &SavedSet) < 0)
266 return errnoAsErrorCode();
267#endif
268 // Attempt to close the file descriptor.
269 // We need to save the error, if one occurs, because our subsequent call to
270 // pthread_sigmask might tamper with errno.
271 int ErrnoFromClose = 0;
272 if (::close(fd: FD) < 0)
273 ErrnoFromClose = errno;
274 // Restore the signal mask back to what we saved earlier.
275 int EC = 0;
276#if LLVM_ENABLE_THREADS
277 EC = pthread_sigmask(SIG_SETMASK, newmask: &SavedSet, oldmask: nullptr);
278#else
279 if (sigprocmask(SIG_SETMASK, &SavedSet, nullptr) < 0)
280 EC = errno;
281#endif
282 // The error code from close takes precedence over the one from
283 // pthread_sigmask.
284 if (ErrnoFromClose)
285 return std::error_code(ErrnoFromClose, std::generic_category());
286 return std::error_code(EC, std::generic_category());
287}
288
289bool Process::StandardInIsUserInput() {
290 return FileDescriptorIsDisplayed(STDIN_FILENO);
291}
292
293bool Process::StandardOutIsDisplayed() {
294 return FileDescriptorIsDisplayed(STDOUT_FILENO);
295}
296
297bool Process::StandardErrIsDisplayed() {
298 return FileDescriptorIsDisplayed(STDERR_FILENO);
299}
300
301bool Process::FileDescriptorIsDisplayed(int fd) {
302#if HAVE_ISATTY
303 return isatty(fd: fd);
304#else
305 // If we don't have isatty, just return false.
306 return false;
307#endif
308}
309
310static unsigned getColumns(int FileID) {
311 // If COLUMNS is defined in the environment, wrap to that many columns.
312 // This matches GCC.
313 if (const char *ColumnsStr = std::getenv(name: "COLUMNS")) {
314 int Columns = std::atoi(nptr: ColumnsStr);
315 if (Columns > 0)
316 return Columns;
317 }
318
319 // Some shells do not export COLUMNS; query the column count via ioctl()
320 // instead if it isn't available.
321 unsigned Columns = 0;
322
323#if defined(HAVE_SYS_IOCTL_H) && !defined(__sun__)
324 struct winsize ws;
325 if (ioctl(fd: FileID, TIOCGWINSZ, &ws) == 0)
326 Columns = ws.ws_col;
327#endif
328
329 return Columns;
330}
331
332unsigned Process::StandardOutColumns() {
333 if (!StandardOutIsDisplayed())
334 return 0;
335
336 return getColumns(FileID: 0);
337}
338
339unsigned Process::StandardErrColumns() {
340 if (!StandardErrIsDisplayed())
341 return 0;
342
343 return getColumns(FileID: 1);
344}
345
346static bool terminalHasColors() {
347 // Check if the current terminal is one of terminals that are known to support
348 // ANSI color escape codes.
349 if (const char *TermStr = std::getenv(name: "TERM")) {
350 return StringSwitch<bool>(TermStr)
351 .Case(S: "ansi", Value: true)
352 .Case(S: "cygwin", Value: true)
353 .Case(S: "linux", Value: true)
354 .StartsWith(S: "screen", Value: true)
355 .StartsWith(S: "xterm", Value: true)
356 .StartsWith(S: "vt100", Value: true)
357 .StartsWith(S: "rxvt", Value: true)
358 .EndsWith(S: "color", Value: true)
359 .Default(Value: false);
360 }
361
362 return false;
363}
364
365bool Process::FileDescriptorHasColors(int fd) {
366 // A file descriptor has colors if it is displayed and the terminal has
367 // colors.
368 return FileDescriptorIsDisplayed(fd) && terminalHasColors();
369}
370
371bool Process::StandardOutHasColors() {
372 return FileDescriptorHasColors(STDOUT_FILENO);
373}
374
375bool Process::StandardErrHasColors() {
376 return FileDescriptorHasColors(STDERR_FILENO);
377}
378
379void Process::UseANSIEscapeCodes(bool /*enable*/) {
380 // No effect.
381}
382
383bool Process::ColorNeedsFlush() {
384 // No, we use ANSI escape sequences.
385 return false;
386}
387
388const char *Process::OutputColor(char code, bool bold, bool bg) {
389 return colorcodes[bg ? 1 : 0][bold ? 1 : 0][code & 15];
390}
391
392const char *Process::OutputBold(bool bg) { return "\033[1m"; }
393
394const char *Process::OutputReverse() { return "\033[7m"; }
395
396const char *Process::ResetColor() { return "\033[0m"; }
397
398#if !HAVE_DECL_ARC4RANDOM
399static unsigned GetRandomNumberSeed() {
400 // Attempt to get the initial seed from /dev/urandom, if possible.
401 int urandomFD = open("/dev/urandom", O_RDONLY);
402
403 if (urandomFD != -1) {
404 unsigned seed;
405 // Don't use a buffered read to avoid reading more data
406 // from /dev/urandom than we need.
407 int count = read(urandomFD, (void *)&seed, sizeof(seed));
408
409 close(urandomFD);
410
411 // Return the seed if the read was successful.
412 if (count == sizeof(seed))
413 return seed;
414 }
415
416 // Otherwise, swizzle the current time and the process ID to form a reasonable
417 // seed.
418 const auto Now = std::chrono::high_resolution_clock::now();
419 return hash_combine(Now.time_since_epoch().count(), ::getpid());
420}
421#endif
422
423unsigned llvm::sys::Process::GetRandomNumber() {
424#if HAVE_DECL_ARC4RANDOM
425 return arc4random();
426#else
427 static int x = (static_cast<void>(::srand(GetRandomNumberSeed())), 0);
428 (void)x;
429 return ::rand();
430#endif
431}
432
433[[noreturn]] void Process::ExitNoCleanup(int RetCode) { _Exit(status: RetCode); }
434