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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"
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#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
65namespace llvm {
66
67using namespace sys;
68
69ProcessInfo::ProcessInfo() : Pid(0), ReturnCode(0) {}
70
71ErrorOr<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  }
96  return errc::no_such_file_or_directory;
97}
98
99static 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
128static 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
147static void TimeOutHandler(int Sig) {
148}
149
150static 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
181static 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
322namespace llvm {
323
324ProcessInfo 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
432std::error_code
433llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
434                                 WindowsEncodingMethod Encoding /*unused*/) {
435  std::error_code EC;
436  llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
437
438  if (EC)
439    return EC;
440
441  OS << Contents;
442
443  if (OS.has_error())
444    return make_error_code(errc::io_error);
445
446  return EC;
447}
448
449bool llvm::sys::argumentsFitWithinSystemLimits(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 = 0;
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}
470