LLVM  6.0.0svn
Program.inc
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1 //===- llvm/Support/Unix/Program.cpp -----------------------------*- 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 //
10 // This file implements the Unix specific portion of the Program class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 //===----------------------------------------------------------------------===//
15 //=== WARNING: Implementation here must contain only generic UNIX code that
16 //=== is guaranteed to work on *all* UNIX variants.
17 //===----------------------------------------------------------------------===//
18 
19 #include "Unix.h"
20 #include "llvm/ADT/StringExtras.h"
21 #include "llvm/Config/config.h"
22 #include "llvm/Support/Compiler.h"
23 #include "llvm/Support/Errc.h"
25 #include "llvm/Support/Path.h"
27 #if HAVE_SYS_STAT_H
28 #include <sys/stat.h>
29 #endif
30 #if HAVE_SYS_RESOURCE_H
31 #include <sys/resource.h>
32 #endif
33 #if HAVE_SIGNAL_H
34 #include <signal.h>
35 #endif
36 #if HAVE_FCNTL_H
37 #include <fcntl.h>
38 #endif
39 #if HAVE_UNISTD_H
40 #include <unistd.h>
41 #endif
42 #ifdef HAVE_POSIX_SPAWN
43 #include <spawn.h>
44 
45 #if defined(__APPLE__)
46 #include <TargetConditionals.h>
47 #endif
48 
49 #if defined(__APPLE__) && !(defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE)
50 #define USE_NSGETENVIRON 1
51 #else
52 #define USE_NSGETENVIRON 0
53 #endif
54 
55 #if !USE_NSGETENVIRON
56  extern char **environ;
57 #else
58 #include <crt_externs.h> // _NSGetEnviron
59 #endif
60 #endif
61 
62 namespace llvm {
63 
64 using namespace sys;
65 
66 ProcessInfo::ProcessInfo() : Pid(0), ReturnCode(0) {}
67 
68 ErrorOr<std::string> sys::findProgramByName(StringRef Name,
69  ArrayRef<StringRef> Paths) {
70  assert(!Name.empty() && "Must have a name!");
71  // Use the given path verbatim if it contains any slashes; this matches
72  // the behavior of sh(1) and friends.
73  if (Name.find('/') != StringRef::npos)
74  return std::string(Name);
75 
76  SmallVector<StringRef, 16> EnvironmentPaths;
77  if (Paths.empty())
78  if (const char *PathEnv = std::getenv("PATH")) {
79  SplitString(PathEnv, EnvironmentPaths, ":");
80  Paths = EnvironmentPaths;
81  }
82 
83  for (auto Path : Paths) {
84  if (Path.empty())
85  continue;
86 
87  // Check to see if this first directory contains the executable...
88  SmallString<128> FilePath(Path);
89  sys::path::append(FilePath, Name);
90  if (sys::fs::can_execute(FilePath.c_str()))
91  return std::string(FilePath.str()); // Found the executable!
92  }
94 }
95 
96 static bool RedirectIO(Optional<StringRef> Path, int FD, std::string* ErrMsg) {
97  if (!Path) // Noop
98  return false;
99  std::string File;
100  if (Path->empty())
101  // Redirect empty paths to /dev/null
102  File = "/dev/null";
103  else
104  File = *Path;
105 
106  // Open the file
107  int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
108  if (InFD == -1) {
109  MakeErrMsg(ErrMsg, "Cannot open file '" + File + "' for "
110  + (FD == 0 ? "input" : "output"));
111  return true;
112  }
113 
114  // Install it as the requested FD
115  if (dup2(InFD, FD) == -1) {
116  MakeErrMsg(ErrMsg, "Cannot dup2");
117  close(InFD);
118  return true;
119  }
120  close(InFD); // Close the original FD
121  return false;
122 }
123 
124 #ifdef HAVE_POSIX_SPAWN
125 static bool RedirectIO_PS(const std::string *Path, int FD, std::string *ErrMsg,
126  posix_spawn_file_actions_t *FileActions) {
127  if (!Path) // Noop
128  return false;
129  const char *File;
130  if (Path->empty())
131  // Redirect empty paths to /dev/null
132  File = "/dev/null";
133  else
134  File = Path->c_str();
135 
136  if (int Err = posix_spawn_file_actions_addopen(
137  FileActions, FD, File,
138  FD == 0 ? O_RDONLY : O_WRONLY | O_CREAT, 0666))
139  return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
140  return false;
141 }
142 #endif
143 
144 static void TimeOutHandler(int Sig) {
145 }
146 
147 static void SetMemoryLimits(unsigned size) {
148 #if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
149  struct rlimit r;
150  __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
151 
152  // Heap size
153  getrlimit (RLIMIT_DATA, &r);
154  r.rlim_cur = limit;
155  setrlimit (RLIMIT_DATA, &r);
156 #ifdef RLIMIT_RSS
157  // Resident set size.
158  getrlimit (RLIMIT_RSS, &r);
159  r.rlim_cur = limit;
160  setrlimit (RLIMIT_RSS, &r);
161 #endif
162 #endif
163 }
164 
165 }
166 
167 static bool Execute(ProcessInfo &PI, StringRef Program, const char **Args,
168  const char **Envp, ArrayRef<Optional<StringRef>> Redirects,
169  unsigned MemoryLimit, std::string *ErrMsg) {
170  if (!llvm::sys::fs::exists(Program)) {
171  if (ErrMsg)
172  *ErrMsg = std::string("Executable \"") + Program.str() +
173  std::string("\" doesn't exist!");
174  return false;
175  }
176 
177  // If this OS has posix_spawn and there is no memory limit being implied, use
178  // posix_spawn. It is more efficient than fork/exec.
179 #ifdef HAVE_POSIX_SPAWN
180  if (MemoryLimit == 0) {
181  posix_spawn_file_actions_t FileActionsStore;
182  posix_spawn_file_actions_t *FileActions = nullptr;
183 
184  // If we call posix_spawn_file_actions_addopen we have to make sure the
185  // c strings we pass to it stay alive until the call to posix_spawn,
186  // so we copy any StringRefs into this variable.
187  std::string RedirectsStorage[3];
188 
189  if (!Redirects.empty()) {
190  assert(Redirects.size() == 3);
191  std::string *RedirectsStr[3] = {nullptr, nullptr, nullptr};
192  for (int I = 0; I < 3; ++I) {
193  if (Redirects[I]) {
194  RedirectsStorage[I] = *Redirects[I];
195  RedirectsStr[I] = &RedirectsStorage[I];
196  }
197  }
198 
199  FileActions = &FileActionsStore;
200  posix_spawn_file_actions_init(FileActions);
201 
202  // Redirect stdin/stdout.
203  if (RedirectIO_PS(RedirectsStr[0], 0, ErrMsg, FileActions) ||
204  RedirectIO_PS(RedirectsStr[1], 1, ErrMsg, FileActions))
205  return false;
206  if (!Redirects[1] || !Redirects[2] || *Redirects[1] != *Redirects[2]) {
207  // Just redirect stderr
208  if (RedirectIO_PS(RedirectsStr[2], 2, ErrMsg, FileActions))
209  return false;
210  } else {
211  // If stdout and stderr should go to the same place, redirect stderr
212  // to the FD already open for stdout.
213  if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
214  return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
215  }
216  }
217 
218  if (!Envp)
219 #if !USE_NSGETENVIRON
220  Envp = const_cast<const char **>(environ);
221 #else
222  // environ is missing in dylibs.
223  Envp = const_cast<const char **>(*_NSGetEnviron());
224 #endif
225 
226  // Explicitly initialized to prevent what appears to be a valgrind false
227  // positive.
228  pid_t PID = 0;
229  int Err = posix_spawn(&PID, Program.str().c_str(), FileActions,
230  /*attrp*/nullptr, const_cast<char **>(Args),
231  const_cast<char **>(Envp));
232 
233  if (FileActions)
234  posix_spawn_file_actions_destroy(FileActions);
235 
236  if (Err)
237  return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
238 
239  PI.Pid = PID;
240 
241  return true;
242  }
243 #endif
244 
245  // Create a child process.
246  int child = fork();
247  switch (child) {
248  // An error occurred: Return to the caller.
249  case -1:
250  MakeErrMsg(ErrMsg, "Couldn't fork");
251  return false;
252 
253  // Child process: Execute the program.
254  case 0: {
255  // Redirect file descriptors...
256  if (!Redirects.empty()) {
257  // Redirect stdin
258  if (RedirectIO(Redirects[0], 0, ErrMsg)) { return false; }
259  // Redirect stdout
260  if (RedirectIO(Redirects[1], 1, ErrMsg)) { return false; }
261  if (Redirects[1] && Redirects[2] && *Redirects[1] == *Redirects[2]) {
262  // If stdout and stderr should go to the same place, redirect stderr
263  // to the FD already open for stdout.
264  if (-1 == dup2(1,2)) {
265  MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
266  return false;
267  }
268  } else {
269  // Just redirect stderr
270  if (RedirectIO(Redirects[2], 2, ErrMsg)) { return false; }
271  }
272  }
273 
274  // Set memory limits
275  if (MemoryLimit!=0) {
276  SetMemoryLimits(MemoryLimit);
277  }
278 
279  // Execute!
280  std::string PathStr = Program;
281  if (Envp != nullptr)
282  execve(PathStr.c_str(),
283  const_cast<char **>(Args),
284  const_cast<char **>(Envp));
285  else
286  execv(PathStr.c_str(),
287  const_cast<char **>(Args));
288  // If the execve() failed, we should exit. Follow Unix protocol and
289  // return 127 if the executable was not found, and 126 otherwise.
290  // Use _exit rather than exit so that atexit functions and static
291  // object destructors cloned from the parent process aren't
292  // redundantly run, and so that any data buffered in stdio buffers
293  // cloned from the parent aren't redundantly written out.
294  _exit(errno == ENOENT ? 127 : 126);
295  }
296 
297  // Parent process: Break out of the switch to do our processing.
298  default:
299  break;
300  }
301 
302  PI.Pid = child;
303 
304  return true;
305 }
306 
307 namespace llvm {
308 
309 ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
310  bool WaitUntilTerminates, std::string *ErrMsg) {
311  struct sigaction Act, Old;
312  assert(PI.Pid && "invalid pid to wait on, process not started?");
313 
314  int WaitPidOptions = 0;
315  pid_t ChildPid = PI.Pid;
316  if (WaitUntilTerminates) {
317  SecondsToWait = 0;
318  } else if (SecondsToWait) {
319  // Install a timeout handler. The handler itself does nothing, but the
320  // simple fact of having a handler at all causes the wait below to return
321  // with EINTR, unlike if we used SIG_IGN.
322  memset(&Act, 0, sizeof(Act));
323  Act.sa_handler = TimeOutHandler;
324  sigemptyset(&Act.sa_mask);
325  sigaction(SIGALRM, &Act, &Old);
326  alarm(SecondsToWait);
327  } else if (SecondsToWait == 0)
328  WaitPidOptions = WNOHANG;
329 
330  // Parent process: Wait for the child process to terminate.
331  int status;
332  ProcessInfo WaitResult;
333 
334  do {
335  WaitResult.Pid = waitpid(ChildPid, &status, WaitPidOptions);
336  } while (WaitUntilTerminates && WaitResult.Pid == -1 && errno == EINTR);
337 
338  if (WaitResult.Pid != PI.Pid) {
339  if (WaitResult.Pid == 0) {
340  // Non-blocking wait.
341  return WaitResult;
342  } else {
343  if (SecondsToWait && errno == EINTR) {
344  // Kill the child.
345  kill(PI.Pid, SIGKILL);
346 
347  // Turn off the alarm and restore the signal handler
348  alarm(0);
349  sigaction(SIGALRM, &Old, nullptr);
350 
351  // Wait for child to die
352  if (wait(&status) != ChildPid)
353  MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
354  else
355  MakeErrMsg(ErrMsg, "Child timed out", 0);
356 
357  WaitResult.ReturnCode = -2; // Timeout detected
358  return WaitResult;
359  } else if (errno != EINTR) {
360  MakeErrMsg(ErrMsg, "Error waiting for child process");
361  WaitResult.ReturnCode = -1;
362  return WaitResult;
363  }
364  }
365  }
366 
367  // We exited normally without timeout, so turn off the timer.
368  if (SecondsToWait && !WaitUntilTerminates) {
369  alarm(0);
370  sigaction(SIGALRM, &Old, nullptr);
371  }
372 
373  // Return the proper exit status. Detect error conditions
374  // so we can return -1 for them and set ErrMsg informatively.
375  int result = 0;
376  if (WIFEXITED(status)) {
377  result = WEXITSTATUS(status);
378  WaitResult.ReturnCode = result;
379 
380  if (result == 127) {
381  if (ErrMsg)
382  *ErrMsg = llvm::sys::StrError(ENOENT);
383  WaitResult.ReturnCode = -1;
384  return WaitResult;
385  }
386  if (result == 126) {
387  if (ErrMsg)
388  *ErrMsg = "Program could not be executed";
389  WaitResult.ReturnCode = -1;
390  return WaitResult;
391  }
392  } else if (WIFSIGNALED(status)) {
393  if (ErrMsg) {
394  *ErrMsg = strsignal(WTERMSIG(status));
395 #ifdef WCOREDUMP
396  if (WCOREDUMP(status))
397  *ErrMsg += " (core dumped)";
398 #endif
399  }
400  // Return a special value to indicate that the process received an unhandled
401  // signal during execution as opposed to failing to execute.
402  WaitResult.ReturnCode = -2;
403  }
404  return WaitResult;
405 }
406 
407  std::error_code sys::ChangeStdinToBinary(){
408  // Do nothing, as Unix doesn't differentiate between text and binary.
409  return std::error_code();
410 }
411 
412  std::error_code sys::ChangeStdoutToBinary(){
413  // Do nothing, as Unix doesn't differentiate between text and binary.
414  return std::error_code();
415 }
416 
417 std::error_code
418 llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
419  WindowsEncodingMethod Encoding /*unused*/) {
420  std::error_code EC;
422 
423  if (EC)
424  return EC;
425 
426  OS << Contents;
427 
428  if (OS.has_error())
430 
431  return EC;
432 }
433 
434 bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program,
435  ArrayRef<const char *> Args) {
436  static long ArgMax = sysconf(_SC_ARG_MAX);
437 
438  // System says no practical limit.
439  if (ArgMax == -1)
440  return true;
441 
442  // Conservatively account for space required by environment variables.
443  long HalfArgMax = ArgMax / 2;
444 
445  size_t ArgLength = Program.size() + 1;
446  for (const char* Arg : Args) {
447  size_t length = strlen(Arg);
448 
449  // Ensure that we do not exceed the MAX_ARG_STRLEN constant on Linux, which
450  // does not have a constant unlike what the man pages would have you
451  // believe. Since this limit is pretty high, perform the check
452  // unconditionally rather than trying to be aggressive and limiting it to
453  // Linux only.
454  if (length >= (32 * 4096))
455  return false;
456 
457  ArgLength += length + 1;
458  if (ArgLength > size_t(HalfArgMax)) {
459  return false;
460  }
461  }
462 
463  return true;
464 }
465 }
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Definition: AllocatorList.h:24
std::error_code ChangeStdoutToBinary()
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Return true if the given arguments fit within system-specific argument length limits.
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Saves the UTF8-encoded contents string into the file FileName using a specific encoding.
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Definition: Program.h:142
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std::error_code ChangeStdinToBinary()
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This function waits for the process specified by PI to finish.
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