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"
24#include "llvm/Support/FileSystem.h"
25#include "llvm/Support/Path.h"
26#include "llvm/Support/raw_ostream.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
62namespace llvm {
63
64using namespace sys;
65
66ProcessInfo::ProcessInfo() : Pid(0), ReturnCode(0) {}
67
68ErrorOr<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  }
93  return errc::no_such_file_or_directory;
94}
95
96static 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
125static 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
144static void TimeOutHandler(int Sig) {
145}
146
147static 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
167static 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
307namespace llvm {
308
309ProcessInfo 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
417std::error_code
418llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
419                                 WindowsEncodingMethod Encoding /*unused*/) {
420  std::error_code EC;
421  llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
422
423  if (EC)
424    return EC;
425
426  OS << Contents;
427
428  if (OS.has_error())
429    return make_error_code(errc::io_error);
430
431  return EC;
432}
433
434bool 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}
466