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#endif
167}
168
169}
170
171static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
172                    const char **envp, const StringRef **redirects,
173                    unsigned memoryLimit, std::string *ErrMsg) {
174  if (!llvm::sys::fs::exists(Program)) {
175    if (ErrMsg)
176      *ErrMsg = std::string("Executable \"") + Program.str() +
177                std::string("\" doesn't exist!");
178    return false;
179  }
180
181  // If this OS has posix_spawn and there is no memory limit being implied, use
182  // posix_spawn.  It is more efficient than fork/exec.
183#ifdef HAVE_POSIX_SPAWN
184  if (memoryLimit == 0) {
185    posix_spawn_file_actions_t FileActionsStore;
186    posix_spawn_file_actions_t *FileActions = nullptr;
187
188    // If we call posix_spawn_file_actions_addopen we have to make sure the
189    // c strings we pass to it stay alive until the call to posix_spawn,
190    // so we copy any StringRefs into this variable.
191    std::string RedirectsStorage[3];
192
193    if (redirects) {
194      std::string *RedirectsStr[3] = {nullptr, nullptr, nullptr};
195      for (int I = 0; I < 3; ++I) {
196        if (redirects[I]) {
197          RedirectsStorage[I] = *redirects[I];
198          RedirectsStr[I] = &RedirectsStorage[I];
199        }
200      }
201
202      FileActions = &FileActionsStore;
203      posix_spawn_file_actions_init(FileActions);
204
205      // Redirect stdin/stdout.
206      if (RedirectIO_PS(RedirectsStr[0], 0, ErrMsg, FileActions) ||
207          RedirectIO_PS(RedirectsStr[1], 1, ErrMsg, FileActions))
208        return false;
209      if (redirects[1] == nullptr || redirects[2] == nullptr ||
210          *redirects[1] != *redirects[2]) {
211        // Just redirect stderr
212        if (RedirectIO_PS(RedirectsStr[2], 2, ErrMsg, FileActions))
213          return false;
214      } else {
215        // If stdout and stderr should go to the same place, redirect stderr
216        // to the FD already open for stdout.
217        if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
218          return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
219      }
220    }
221
222    if (!envp)
223#if !USE_NSGETENVIRON
224      envp = const_cast<const char **>(environ);
225#else
226      // environ is missing in dylibs.
227      envp = const_cast<const char **>(*_NSGetEnviron());
228#endif
229
230    // Explicitly initialized to prevent what appears to be a valgrind false
231    // positive.
232    pid_t PID = 0;
233    int Err = posix_spawn(&PID, Program.str().c_str(), FileActions,
234                          /*attrp*/nullptr, const_cast<char **>(args),
235                          const_cast<char **>(envp));
236
237    if (FileActions)
238      posix_spawn_file_actions_destroy(FileActions);
239
240    if (Err)
241     return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
242
243    PI.Pid = PID;
244
245    return true;
246  }
247#endif
248
249  // Create a child process.
250  int child = fork();
251  switch (child) {
252    // An error occurred:  Return to the caller.
253    case -1:
254      MakeErrMsg(ErrMsg, "Couldn't fork");
255      return false;
256
257    // Child process: Execute the program.
258    case 0: {
259      // Redirect file descriptors...
260      if (redirects) {
261        // Redirect stdin
262        if (RedirectIO(redirects[0], 0, ErrMsg)) { return false; }
263        // Redirect stdout
264        if (RedirectIO(redirects[1], 1, ErrMsg)) { return false; }
265        if (redirects[1] && redirects[2] &&
266            *(redirects[1]) == *(redirects[2])) {
267          // If stdout and stderr should go to the same place, redirect stderr
268          // to the FD already open for stdout.
269          if (-1 == dup2(1,2)) {
270            MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
271            return false;
272          }
273        } else {
274          // Just redirect stderr
275          if (RedirectIO(redirects[2], 2, ErrMsg)) { return false; }
276        }
277      }
278
279      // Set memory limits
280      if (memoryLimit!=0) {
281        SetMemoryLimits(memoryLimit);
282      }
283
284      // Execute!
285      std::string PathStr = Program;
286      if (envp != nullptr)
287        execve(PathStr.c_str(),
288               const_cast<char **>(args),
289               const_cast<char **>(envp));
290      else
291        execv(PathStr.c_str(),
292              const_cast<char **>(args));
293      // If the execve() failed, we should exit. Follow Unix protocol and
294      // return 127 if the executable was not found, and 126 otherwise.
295      // Use _exit rather than exit so that atexit functions and static
296      // object destructors cloned from the parent process aren't
297      // redundantly run, and so that any data buffered in stdio buffers
298      // cloned from the parent aren't redundantly written out.
299      _exit(errno == ENOENT ? 127 : 126);
300    }
301
302    // Parent process: Break out of the switch to do our processing.
303    default:
304      break;
305  }
306
307  PI.Pid = child;
308
309  return true;
310}
311
312namespace llvm {
313
314ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
315                      bool WaitUntilTerminates, std::string *ErrMsg) {
316  struct sigaction Act, Old;
317  assert(PI.Pid && "invalid pid to wait on, process not started?");
318
319  int WaitPidOptions = 0;
320  pid_t ChildPid = PI.Pid;
321  if (WaitUntilTerminates) {
322    SecondsToWait = 0;
323  } else if (SecondsToWait) {
324    // Install a timeout handler.  The handler itself does nothing, but the
325    // simple fact of having a handler at all causes the wait below to return
326    // with EINTR, unlike if we used SIG_IGN.
327    memset(&Act, 0, sizeof(Act));
328    Act.sa_handler = TimeOutHandler;
329    sigemptyset(&Act.sa_mask);
330    sigaction(SIGALRM, &Act, &Old);
331    alarm(SecondsToWait);
332  } else if (SecondsToWait == 0)
333    WaitPidOptions = WNOHANG;
334
335  // Parent process: Wait for the child process to terminate.
336  int status;
337  ProcessInfo WaitResult;
338
339  do {
340    WaitResult.Pid = waitpid(ChildPid, &status, WaitPidOptions);
341  } while (WaitUntilTerminates && WaitResult.Pid == -1 && errno == EINTR);
342
343  if (WaitResult.Pid != PI.Pid) {
344    if (WaitResult.Pid == 0) {
345      // Non-blocking wait.
346      return WaitResult;
347    } else {
348      if (SecondsToWait && errno == EINTR) {
349        // Kill the child.
350        kill(PI.Pid, SIGKILL);
351
352        // Turn off the alarm and restore the signal handler
353        alarm(0);
354        sigaction(SIGALRM, &Old, nullptr);
355
356        // Wait for child to die
357        if (wait(&status) != ChildPid)
358          MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
359        else
360          MakeErrMsg(ErrMsg, "Child timed out", 0);
361
362        WaitResult.ReturnCode = -2; // Timeout detected
363        return WaitResult;
364      } else if (errno != EINTR) {
365        MakeErrMsg(ErrMsg, "Error waiting for child process");
366        WaitResult.ReturnCode = -1;
367        return WaitResult;
368      }
369    }
370  }
371
372  // We exited normally without timeout, so turn off the timer.
373  if (SecondsToWait && !WaitUntilTerminates) {
374    alarm(0);
375    sigaction(SIGALRM, &Old, nullptr);
376  }
377
378  // Return the proper exit status. Detect error conditions
379  // so we can return -1 for them and set ErrMsg informatively.
380  int result = 0;
381  if (WIFEXITED(status)) {
382    result = WEXITSTATUS(status);
383    WaitResult.ReturnCode = result;
384
385    if (result == 127) {
386      if (ErrMsg)
387        *ErrMsg = llvm::sys::StrError(ENOENT);
388      WaitResult.ReturnCode = -1;
389      return WaitResult;
390    }
391    if (result == 126) {
392      if (ErrMsg)
393        *ErrMsg = "Program could not be executed";
394      WaitResult.ReturnCode = -1;
395      return WaitResult;
396    }
397  } else if (WIFSIGNALED(status)) {
398    if (ErrMsg) {
399      *ErrMsg = strsignal(WTERMSIG(status));
400#ifdef WCOREDUMP
401      if (WCOREDUMP(status))
402        *ErrMsg += " (core dumped)";
403#endif
404    }
405    // Return a special value to indicate that the process received an unhandled
406    // signal during execution as opposed to failing to execute.
407    WaitResult.ReturnCode = -2;
408  }
409  return WaitResult;
410}
411
412  std::error_code sys::ChangeStdinToBinary(){
413  // Do nothing, as Unix doesn't differentiate between text and binary.
414    return std::error_code();
415}
416
417  std::error_code sys::ChangeStdoutToBinary(){
418  // Do nothing, as Unix doesn't differentiate between text and binary.
419    return std::error_code();
420}
421
422std::error_code
423llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
424                                 WindowsEncodingMethod Encoding /*unused*/) {
425  std::error_code EC;
426  llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
427
428  if (EC)
429    return EC;
430
431  OS << Contents;
432
433  if (OS.has_error())
434    return make_error_code(errc::io_error);
435
436  return EC;
437}
438
439bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef<const char*> Args) {
440  static long ArgMax = sysconf(_SC_ARG_MAX);
441
442  // System says no practical limit.
443  if (ArgMax == -1)
444    return true;
445
446  // Conservatively account for space required by environment variables.
447  long HalfArgMax = ArgMax / 2;
448
449  size_t ArgLength = Program.size() + 1;
450  for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
451       I != E; ++I) {
452    size_t length = strlen(*I);
453
454    // Ensure that we do not exceed the MAX_ARG_STRLEN constant on Linux, which
455    // does not have a constant unlike what the man pages would have you
456    // believe. Since this limit is pretty high, perform the check
457    // unconditionally rather than trying to be aggressive and limiting it to
458    // Linux only.
459    if (length >= (32 * 4096))
460      return false;
461
462    ArgLength += length + 1;
463    if (ArgLength > size_t(HalfArgMax)) {
464      return false;
465    }
466  }
467
468  return true;
469}
470}
471