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(const 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{
149#if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
150  struct rlimit r;
151  __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
152
153  // Heap size
154  getrlimit (RLIMIT_DATA, &r);
155  r.rlim_cur = limit;
156  setrlimit (RLIMIT_DATA, &r);
157#ifdef RLIMIT_RSS
158  // Resident set size.
159  getrlimit (RLIMIT_RSS, &r);
160  r.rlim_cur = limit;
161  setrlimit (RLIMIT_RSS, &r);
162#endif
163#endif
164}
165
166}
167
168static bool Execute(ProcessInfo &PI, StringRef Program, const char **args,
169                    const char **envp, const StringRef **redirects,
170                    unsigned memoryLimit, std::string *ErrMsg) {
171  if (!llvm::sys::fs::exists(Program)) {
172    if (ErrMsg)
173      *ErrMsg = std::string("Executable \"") + Program.str() +
174                std::string("\" doesn't exist!");
175    return false;
176  }
177
178  // If this OS has posix_spawn and there is no memory limit being implied, use
179  // posix_spawn.  It is more efficient than fork/exec.
180#ifdef HAVE_POSIX_SPAWN
181  if (memoryLimit == 0) {
182    posix_spawn_file_actions_t FileActionsStore;
183    posix_spawn_file_actions_t *FileActions = nullptr;
184
185    // If we call posix_spawn_file_actions_addopen we have to make sure the
186    // c strings we pass to it stay alive until the call to posix_spawn,
187    // so we copy any StringRefs into this variable.
188    std::string RedirectsStorage[3];
189
190    if (redirects) {
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] == nullptr || redirects[2] == nullptr ||
207          *redirects[1] != *redirects[2]) {
208        // Just redirect stderr
209        if (RedirectIO_PS(RedirectsStr[2], 2, ErrMsg, FileActions))
210          return false;
211      } else {
212        // If stdout and stderr should go to the same place, redirect stderr
213        // to the FD already open for stdout.
214        if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
215          return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
216      }
217    }
218
219    if (!envp)
220#if !USE_NSGETENVIRON
221      envp = const_cast<const char **>(environ);
222#else
223      // environ is missing in dylibs.
224      envp = const_cast<const char **>(*_NSGetEnviron());
225#endif
226
227    // Explicitly initialized to prevent what appears to be a valgrind false
228    // positive.
229    pid_t PID = 0;
230    int Err = posix_spawn(&PID, Program.str().c_str(), FileActions,
231                          /*attrp*/nullptr, const_cast<char **>(args),
232                          const_cast<char **>(envp));
233
234    if (FileActions)
235      posix_spawn_file_actions_destroy(FileActions);
236
237    if (Err)
238     return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
239
240    PI.Pid = PID;
241
242    return true;
243  }
244#endif
245
246  // Create a child process.
247  int child = fork();
248  switch (child) {
249    // An error occurred:  Return to the caller.
250    case -1:
251      MakeErrMsg(ErrMsg, "Couldn't fork");
252      return false;
253
254    // Child process: Execute the program.
255    case 0: {
256      // Redirect file descriptors...
257      if (redirects) {
258        // Redirect stdin
259        if (RedirectIO(redirects[0], 0, ErrMsg)) { return false; }
260        // Redirect stdout
261        if (RedirectIO(redirects[1], 1, ErrMsg)) { return false; }
262        if (redirects[1] && redirects[2] &&
263            *(redirects[1]) == *(redirects[2])) {
264          // If stdout and stderr should go to the same place, redirect stderr
265          // to the FD already open for stdout.
266          if (-1 == dup2(1,2)) {
267            MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
268            return false;
269          }
270        } else {
271          // Just redirect stderr
272          if (RedirectIO(redirects[2], 2, ErrMsg)) { return false; }
273        }
274      }
275
276      // Set memory limits
277      if (memoryLimit!=0) {
278        SetMemoryLimits(memoryLimit);
279      }
280
281      // Execute!
282      std::string PathStr = Program;
283      if (envp != nullptr)
284        execve(PathStr.c_str(),
285               const_cast<char **>(args),
286               const_cast<char **>(envp));
287      else
288        execv(PathStr.c_str(),
289              const_cast<char **>(args));
290      // If the execve() failed, we should exit. Follow Unix protocol and
291      // return 127 if the executable was not found, and 126 otherwise.
292      // Use _exit rather than exit so that atexit functions and static
293      // object destructors cloned from the parent process aren't
294      // redundantly run, and so that any data buffered in stdio buffers
295      // cloned from the parent aren't redundantly written out.
296      _exit(errno == ENOENT ? 127 : 126);
297    }
298
299    // Parent process: Break out of the switch to do our processing.
300    default:
301      break;
302  }
303
304  PI.Pid = child;
305
306  return true;
307}
308
309namespace llvm {
310
311ProcessInfo sys::Wait(const ProcessInfo &PI, unsigned SecondsToWait,
312                      bool WaitUntilTerminates, std::string *ErrMsg) {
313  struct sigaction Act, Old;
314  assert(PI.Pid && "invalid pid to wait on, process not started?");
315
316  int WaitPidOptions = 0;
317  pid_t ChildPid = PI.Pid;
318  if (WaitUntilTerminates) {
319    SecondsToWait = 0;
320  } else if (SecondsToWait) {
321    // Install a timeout handler.  The handler itself does nothing, but the
322    // simple fact of having a handler at all causes the wait below to return
323    // with EINTR, unlike if we used SIG_IGN.
324    memset(&Act, 0, sizeof(Act));
325    Act.sa_handler = TimeOutHandler;
326    sigemptyset(&Act.sa_mask);
327    sigaction(SIGALRM, &Act, &Old);
328    alarm(SecondsToWait);
329  } else if (SecondsToWait == 0)
330    WaitPidOptions = WNOHANG;
331
332  // Parent process: Wait for the child process to terminate.
333  int status;
334  ProcessInfo WaitResult;
335
336  do {
337    WaitResult.Pid = waitpid(ChildPid, &status, WaitPidOptions);
338  } while (WaitUntilTerminates && WaitResult.Pid == -1 && errno == EINTR);
339
340  if (WaitResult.Pid != PI.Pid) {
341    if (WaitResult.Pid == 0) {
342      // Non-blocking wait.
343      return WaitResult;
344    } else {
345      if (SecondsToWait && errno == EINTR) {
346        // Kill the child.
347        kill(PI.Pid, SIGKILL);
348
349        // Turn off the alarm and restore the signal handler
350        alarm(0);
351        sigaction(SIGALRM, &Old, nullptr);
352
353        // Wait for child to die
354        if (wait(&status) != ChildPid)
355          MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
356        else
357          MakeErrMsg(ErrMsg, "Child timed out", 0);
358
359        WaitResult.ReturnCode = -2; // Timeout detected
360        return WaitResult;
361      } else if (errno != EINTR) {
362        MakeErrMsg(ErrMsg, "Error waiting for child process");
363        WaitResult.ReturnCode = -1;
364        return WaitResult;
365      }
366    }
367  }
368
369  // We exited normally without timeout, so turn off the timer.
370  if (SecondsToWait && !WaitUntilTerminates) {
371    alarm(0);
372    sigaction(SIGALRM, &Old, nullptr);
373  }
374
375  // Return the proper exit status. Detect error conditions
376  // so we can return -1 for them and set ErrMsg informatively.
377  int result = 0;
378  if (WIFEXITED(status)) {
379    result = WEXITSTATUS(status);
380    WaitResult.ReturnCode = result;
381
382    if (result == 127) {
383      if (ErrMsg)
384        *ErrMsg = llvm::sys::StrError(ENOENT);
385      WaitResult.ReturnCode = -1;
386      return WaitResult;
387    }
388    if (result == 126) {
389      if (ErrMsg)
390        *ErrMsg = "Program could not be executed";
391      WaitResult.ReturnCode = -1;
392      return WaitResult;
393    }
394  } else if (WIFSIGNALED(status)) {
395    if (ErrMsg) {
396      *ErrMsg = strsignal(WTERMSIG(status));
397#ifdef WCOREDUMP
398      if (WCOREDUMP(status))
399        *ErrMsg += " (core dumped)";
400#endif
401    }
402    // Return a special value to indicate that the process received an unhandled
403    // signal during execution as opposed to failing to execute.
404    WaitResult.ReturnCode = -2;
405  }
406  return WaitResult;
407}
408
409  std::error_code sys::ChangeStdinToBinary(){
410  // Do nothing, as Unix doesn't differentiate between text and binary.
411    return std::error_code();
412}
413
414  std::error_code sys::ChangeStdoutToBinary(){
415  // Do nothing, as Unix doesn't differentiate between text and binary.
416    return std::error_code();
417}
418
419std::error_code
420llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
421                                 WindowsEncodingMethod Encoding /*unused*/) {
422  std::error_code EC;
423  llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
424
425  if (EC)
426    return EC;
427
428  OS << Contents;
429
430  if (OS.has_error())
431    return make_error_code(errc::io_error);
432
433  return EC;
434}
435
436bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program, ArrayRef<const char*> Args) {
437  static long ArgMax = sysconf(_SC_ARG_MAX);
438
439  // System says no practical limit.
440  if (ArgMax == -1)
441    return true;
442
443  // Conservatively account for space required by environment variables.
444  long HalfArgMax = ArgMax / 2;
445
446  size_t ArgLength = Program.size() + 1;
447  for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
448       I != E; ++I) {
449    size_t length = strlen(*I);
450
451    // Ensure that we do not exceed the MAX_ARG_STRLEN constant on Linux, which
452    // does not have a constant unlike what the man pages would have you
453    // believe. Since this limit is pretty high, perform the check
454    // unconditionally rather than trying to be aggressive and limiting it to
455    // Linux only.
456    if (length >= (32 * 4096))
457      return false;
458
459    ArgLength += length + 1;
460    if (ArgLength > size_t(HalfArgMax)) {
461      return false;
462    }
463  }
464
465  return true;
466}
467}
468