LLVM  4.0.0
Unix/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 #ifdef __sun__
44 #define _RESTRICT_KYWD
45 #endif
46 #include <spawn.h>
47 
48 #if defined(__APPLE__)
49 #include <TargetConditionals.h>
50 #endif
51 
52 #if defined(__APPLE__) && !(defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE)
53 #define USE_NSGETENVIRON 1
54 #else
55 #define USE_NSGETENVIRON 0
56 #endif
57 
58 #if !USE_NSGETENVIRON
59  extern char **environ;
60 #else
61 #include <crt_externs.h> // _NSGetEnviron
62 #endif
63 #endif
64 
65 namespace llvm {
66 
67 using namespace sys;
68 
69 ProcessInfo::ProcessInfo() : Pid(0), ReturnCode(0) {}
70 
71 ErrorOr<std::string> sys::findProgramByName(StringRef Name,
72  ArrayRef<StringRef> Paths) {
73  assert(!Name.empty() && "Must have a name!");
74  // Use the given path verbatim if it contains any slashes; this matches
75  // the behavior of sh(1) and friends.
76  if (Name.find('/') != StringRef::npos)
77  return std::string(Name);
78 
79  SmallVector<StringRef, 16> EnvironmentPaths;
80  if (Paths.empty())
81  if (const char *PathEnv = std::getenv("PATH")) {
82  SplitString(PathEnv, EnvironmentPaths, ":");
83  Paths = EnvironmentPaths;
84  }
85 
86  for (auto Path : Paths) {
87  if (Path.empty())
88  continue;
89 
90  // Check to see if this first directory contains the executable...
91  SmallString<128> FilePath(Path);
92  sys::path::append(FilePath, Name);
93  if (sys::fs::can_execute(FilePath.c_str()))
94  return std::string(FilePath.str()); // Found the executable!
95  }
97 }
98 
99 static bool RedirectIO(const StringRef *Path, int FD, std::string* ErrMsg) {
100  if (!Path) // Noop
101  return false;
102  std::string File;
103  if (Path->empty())
104  // Redirect empty paths to /dev/null
105  File = "/dev/null";
106  else
107  File = *Path;
108 
109  // Open the file
110  int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
111  if (InFD == -1) {
112  MakeErrMsg(ErrMsg, "Cannot open file '" + File + "' for "
113  + (FD == 0 ? "input" : "output"));
114  return true;
115  }
116 
117  // Install it as the requested FD
118  if (dup2(InFD, FD) == -1) {
119  MakeErrMsg(ErrMsg, "Cannot dup2");
120  close(InFD);
121  return true;
122  }
123  close(InFD); // Close the original FD
124  return false;
125 }
126 
127 #ifdef HAVE_POSIX_SPAWN
128 static bool RedirectIO_PS(const std::string *Path, int FD, std::string *ErrMsg,
129  posix_spawn_file_actions_t *FileActions) {
130  if (!Path) // Noop
131  return false;
132  const char *File;
133  if (Path->empty())
134  // Redirect empty paths to /dev/null
135  File = "/dev/null";
136  else
137  File = Path->c_str();
138 
139  if (int Err = posix_spawn_file_actions_addopen(
140  FileActions, FD, File,
141  FD == 0 ? O_RDONLY : O_WRONLY | O_CREAT, 0666))
142  return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
143  return false;
144 }
145 #endif
146 
147 static void TimeOutHandler(int Sig) {
148 }
149 
150 static void SetMemoryLimits (unsigned size)
151 {
152 #if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
153  struct rlimit r;
154  __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
155 
156  // Heap size
157  getrlimit (RLIMIT_DATA, &r);
158  r.rlim_cur = limit;
159  setrlimit (RLIMIT_DATA, &r);
160 #ifdef RLIMIT_RSS
161  // Resident set size.
162  getrlimit (RLIMIT_RSS, &r);
163  r.rlim_cur = limit;
164  setrlimit (RLIMIT_RSS, &r);
165 #endif
166 #ifdef RLIMIT_AS // e.g. NetBSD doesn't have it.
167  // Don't set virtual memory limit if built with any Sanitizer. They need 80Tb
168  // of virtual memory for shadow memory mapping.
169 #if !LLVM_MEMORY_SANITIZER_BUILD && !LLVM_ADDRESS_SANITIZER_BUILD
170  // Virtual memory.
171  getrlimit (RLIMIT_AS, &r);
172  r.rlim_cur = limit;
173  setrlimit (RLIMIT_AS, &r);
174 #endif
175 #endif
176 #endif
177 }
178 
179 }
180 
181 static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
182  const char **envp, const StringRef **redirects,
183  unsigned memoryLimit, std::string *ErrMsg) {
184  if (!llvm::sys::fs::exists(Program)) {
185  if (ErrMsg)
186  *ErrMsg = std::string("Executable \"") + Program.str() +
187  std::string("\" doesn't exist!");
188  return false;
189  }
190 
191  // If this OS has posix_spawn and there is no memory limit being implied, use
192  // posix_spawn. It is more efficient than fork/exec.
193 #ifdef HAVE_POSIX_SPAWN
194  if (memoryLimit == 0) {
195  posix_spawn_file_actions_t FileActionsStore;
196  posix_spawn_file_actions_t *FileActions = nullptr;
197 
198  // If we call posix_spawn_file_actions_addopen we have to make sure the
199  // c strings we pass to it stay alive until the call to posix_spawn,
200  // so we copy any StringRefs into this variable.
201  std::string RedirectsStorage[3];
202 
203  if (redirects) {
204  std::string *RedirectsStr[3] = {nullptr, nullptr, nullptr};
205  for (int I = 0; I < 3; ++I) {
206  if (redirects[I]) {
207  RedirectsStorage[I] = *redirects[I];
208  RedirectsStr[I] = &RedirectsStorage[I];
209  }
210  }
211 
212  FileActions = &FileActionsStore;
213  posix_spawn_file_actions_init(FileActions);
214 
215  // Redirect stdin/stdout.
216  if (RedirectIO_PS(RedirectsStr[0], 0, ErrMsg, FileActions) ||
217  RedirectIO_PS(RedirectsStr[1], 1, ErrMsg, FileActions))
218  return false;
219  if (redirects[1] == nullptr || redirects[2] == nullptr ||
220  *redirects[1] != *redirects[2]) {
221  // Just redirect stderr
222  if (RedirectIO_PS(RedirectsStr[2], 2, ErrMsg, FileActions))
223  return false;
224  } else {
225  // If stdout and stderr should go to the same place, redirect stderr
226  // to the FD already open for stdout.
227  if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
228  return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
229  }
230  }
231 
232  if (!envp)
233 #if !USE_NSGETENVIRON
234  envp = const_cast<const char **>(environ);
235 #else
236  // environ is missing in dylibs.
237  envp = const_cast<const char **>(*_NSGetEnviron());
238 #endif
239 
240  // Explicitly initialized to prevent what appears to be a valgrind false
241  // positive.
242  pid_t PID = 0;
243  int Err = posix_spawn(&PID, Program.str().c_str(), FileActions,
244  /*attrp*/nullptr, const_cast<char **>(args),
245  const_cast<char **>(envp));
246 
247  if (FileActions)
248  posix_spawn_file_actions_destroy(FileActions);
249 
250  if (Err)
251  return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
252 
253  PI.Pid = PID;
254 
255  return true;
256  }
257 #endif
258 
259  // Create a child process.
260  int child = fork();
261  switch (child) {
262  // An error occurred: Return to the caller.
263  case -1:
264  MakeErrMsg(ErrMsg, "Couldn't fork");
265  return false;
266 
267  // Child process: Execute the program.
268  case 0: {
269  // Redirect file descriptors...
270  if (redirects) {
271  // Redirect stdin
272  if (RedirectIO(redirects[0], 0, ErrMsg)) { return false; }
273  // Redirect stdout
274  if (RedirectIO(redirects[1], 1, ErrMsg)) { return false; }
275  if (redirects[1] && redirects[2] &&
276  *(redirects[1]) == *(redirects[2])) {
277  // If stdout and stderr should go to the same place, redirect stderr
278  // to the FD already open for stdout.
279  if (-1 == dup2(1,2)) {
280  MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
281  return false;
282  }
283  } else {
284  // Just redirect stderr
285  if (RedirectIO(redirects[2], 2, ErrMsg)) { return false; }
286  }
287  }
288 
289  // Set memory limits
290  if (memoryLimit!=0) {
291  SetMemoryLimits(memoryLimit);
292  }
293 
294  // Execute!
295  std::string PathStr = Program;
296  if (envp != nullptr)
297  execve(PathStr.c_str(),
298  const_cast<char **>(args),
299  const_cast<char **>(envp));
300  else
301  execv(PathStr.c_str(),
302  const_cast<char **>(args));
303  // If the execve() failed, we should exit. Follow Unix protocol and
304  // return 127 if the executable was not found, and 126 otherwise.
305  // Use _exit rather than exit so that atexit functions and static
306  // object destructors cloned from the parent process aren't
307  // redundantly run, and so that any data buffered in stdio buffers
308  // cloned from the parent aren't redundantly written out.
309  _exit(errno == ENOENT ? 127 : 126);
310  }
311 
312  // Parent process: Break out of the switch to do our processing.
313  default:
314  break;
315  }
316 
317  PI.Pid = child;
318 
319  return true;
320 }
321 
322 namespace llvm {
323 
324 ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
325  bool WaitUntilTerminates, std::string *ErrMsg) {
326  struct sigaction Act, Old;
327  assert(PI.Pid && "invalid pid to wait on, process not started?");
328 
329  int WaitPidOptions = 0;
330  pid_t ChildPid = PI.Pid;
331  if (WaitUntilTerminates) {
332  SecondsToWait = 0;
333  } else if (SecondsToWait) {
334  // Install a timeout handler. The handler itself does nothing, but the
335  // simple fact of having a handler at all causes the wait below to return
336  // with EINTR, unlike if we used SIG_IGN.
337  memset(&Act, 0, sizeof(Act));
338  Act.sa_handler = TimeOutHandler;
339  sigemptyset(&Act.sa_mask);
340  sigaction(SIGALRM, &Act, &Old);
341  alarm(SecondsToWait);
342  } else if (SecondsToWait == 0)
343  WaitPidOptions = WNOHANG;
344 
345  // Parent process: Wait for the child process to terminate.
346  int status;
347  ProcessInfo WaitResult;
348 
349  do {
350  WaitResult.Pid = waitpid(ChildPid, &status, WaitPidOptions);
351  } while (WaitUntilTerminates && WaitResult.Pid == -1 && errno == EINTR);
352 
353  if (WaitResult.Pid != PI.Pid) {
354  if (WaitResult.Pid == 0) {
355  // Non-blocking wait.
356  return WaitResult;
357  } else {
358  if (SecondsToWait && errno == EINTR) {
359  // Kill the child.
360  kill(PI.Pid, SIGKILL);
361 
362  // Turn off the alarm and restore the signal handler
363  alarm(0);
364  sigaction(SIGALRM, &Old, nullptr);
365 
366  // Wait for child to die
367  if (wait(&status) != ChildPid)
368  MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
369  else
370  MakeErrMsg(ErrMsg, "Child timed out", 0);
371 
372  WaitResult.ReturnCode = -2; // Timeout detected
373  return WaitResult;
374  } else if (errno != EINTR) {
375  MakeErrMsg(ErrMsg, "Error waiting for child process");
376  WaitResult.ReturnCode = -1;
377  return WaitResult;
378  }
379  }
380  }
381 
382  // We exited normally without timeout, so turn off the timer.
383  if (SecondsToWait && !WaitUntilTerminates) {
384  alarm(0);
385  sigaction(SIGALRM, &Old, nullptr);
386  }
387 
388  // Return the proper exit status. Detect error conditions
389  // so we can return -1 for them and set ErrMsg informatively.
390  int result = 0;
391  if (WIFEXITED(status)) {
392  result = WEXITSTATUS(status);
393  WaitResult.ReturnCode = result;
394 
395  if (result == 127) {
396  if (ErrMsg)
397  *ErrMsg = llvm::sys::StrError(ENOENT);
398  WaitResult.ReturnCode = -1;
399  return WaitResult;
400  }
401  if (result == 126) {
402  if (ErrMsg)
403  *ErrMsg = "Program could not be executed";
404  WaitResult.ReturnCode = -1;
405  return WaitResult;
406  }
407  } else if (WIFSIGNALED(status)) {
408  if (ErrMsg) {
409  *ErrMsg = strsignal(WTERMSIG(status));
410 #ifdef WCOREDUMP
411  if (WCOREDUMP(status))
412  *ErrMsg += " (core dumped)";
413 #endif
414  }
415  // Return a special value to indicate that the process received an unhandled
416  // signal during execution as opposed to failing to execute.
417  WaitResult.ReturnCode = -2;
418  }
419  return WaitResult;
420 }
421 
422  std::error_code sys::ChangeStdinToBinary(){
423  // Do nothing, as Unix doesn't differentiate between text and binary.
424  return std::error_code();
425 }
426 
427  std::error_code sys::ChangeStdoutToBinary(){
428  // Do nothing, as Unix doesn't differentiate between text and binary.
429  return std::error_code();
430 }
431 
432 std::error_code
433 llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
434  WindowsEncodingMethod Encoding /*unused*/) {
435  std::error_code EC;
437 
438  if (EC)
439  return EC;
440 
441  OS << Contents;
442 
443  if (OS.has_error())
445 
446  return EC;
447 }
448 
449 bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef<const char*> Args) {
450  static long ArgMax = sysconf(_SC_ARG_MAX);
451 
452  // System says no practical limit.
453  if (ArgMax == -1)
454  return true;
455 
456  // Conservatively account for space required by environment variables.
457  long HalfArgMax = ArgMax / 2;
458 
459  size_t ArgLength = Program.size() + 1;
460  for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
461  I != E; ++I) {
462  ArgLength += strlen(*I) + 1;
463  if (ArgLength > size_t(HalfArgMax)) {
464  return false;
465  }
466  }
467  return true;
468 }
469 }
bool can_execute(const Twine &Path)
Can we execute this file?
std::error_code ChangeStdoutToBinary()
void append(SmallVectorImpl< char > &path, const Twine &a, const Twine &b="", const Twine &c="", const Twine &d="")
Append to path.
Definition: Path.cpp:448
std::string StrError()
Returns a string representation of the errno value, using whatever thread-safe variant of strerror() ...
Definition: Errno.cpp:32
std::error_code make_error_code(BitcodeError E)
static GCRegistry::Add< CoreCLRGC > E("coreclr","CoreCLR-compatible GC")
void SplitString(StringRef Source, SmallVectorImpl< StringRef > &OutFragments, StringRef Delimiters=" \t\n\v\f\r")
SplitString - Split up the specified string according to the specified delimiters, appending the result fragments to the output list.
static bool Execute(ProcessInfo &PI, StringRef Program, const char **args, const char **env, const StringRef **Redirects, unsigned memoryLimit, std::string *ErrMsg)
bool commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef< const char * > Args)
Return true if the given arguments fit within system-specific argument length limits.
std::error_code writeFileWithEncoding(StringRef FileName, StringRef Contents, WindowsEncodingMethod Encoding=WEM_UTF8)
Saves the UTF8-encoded contents string into the file FileName using a specific encoding.
bool MakeErrMsg(std::string *ErrMsg, const std::string &prefix)
WindowsEncodingMethod
File encoding options when writing contents that a non-UTF8 tool will read (on Windows systems)...
Definition: Program.h:139
The file should be opened in text mode on platforms that make this distinction.
Definition: FileSystem.h:638
std::error_code ChangeStdinToBinary()
A raw_ostream that writes to a file descriptor.
Definition: raw_ostream.h:357
static const size_t npos
Definition: StringRef.h:51
#define I(x, y, z)
Definition: MD5.cpp:54
ErrorOr< std::string > findProgramByName(StringRef Name, ArrayRef< StringRef > Paths=None)
Find the first executable file Name in Paths.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
ProcessInfo Wait(const ProcessInfo &PI, unsigned SecondsToWait, bool WaitUntilTerminates, std::string *ErrMsg=nullptr)
This function waits for the process specified by PI to finish.
std::error_code status(const Twine &path, file_status &result)
Get file status as if by POSIX stat().
bool exists(file_status status)
Does file exist?
Definition: Path.cpp:940