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/Support/Compiler.h"
22#include "llvm/Support/FileSystem.h"
23#include "llvm/Support/raw_ostream.h"
24#include <llvm/Config/config.h>
25#if HAVE_SYS_STAT_H
26#include <sys/stat.h>
27#endif
28#if HAVE_SYS_RESOURCE_H
29#include <sys/resource.h>
30#endif
31#if HAVE_SIGNAL_H
32#include <signal.h>
33#endif
34#if HAVE_FCNTL_H
35#include <fcntl.h>
36#endif
37#if HAVE_UNISTD_H
38#include <unistd.h>
39#endif
40#ifdef HAVE_POSIX_SPAWN
41#ifdef __sun__
42#define  _RESTRICT_KYWD
43#endif
44#include <spawn.h>
45#if defined(__APPLE__)
46#include <TargetConditionals.h>
47#endif
48#if !defined(__APPLE__) || defined(TARGET_OS_IPHONE)
49  extern char **environ;
50#else
51#include <crt_externs.h> // _NSGetEnviron
52#endif
53#endif
54
55namespace llvm {
56
57using namespace sys;
58
59ProcessInfo::ProcessInfo() : Pid(0), ReturnCode(0) {}
60
61ErrorOr<std::string> sys::findProgramByName(StringRef Name,
62                                            ArrayRef<StringRef> Paths) {
63  assert(!Name.empty() && "Must have a name!");
64  // Use the given path verbatim if it contains any slashes; this matches
65  // the behavior of sh(1) and friends.
66  if (Name.find('/') != StringRef::npos)
67    return std::string(Name);
68
69  SmallVector<StringRef, 16> EnvironmentPaths;
70  if (Paths.empty())
71    if (const char *PathEnv = std::getenv("PATH")) {
72      SplitString(PathEnv, EnvironmentPaths, ":");
73      Paths = EnvironmentPaths;
74    }
75
76  for (auto Path : Paths) {
77    if (Path.empty())
78      continue;
79
80    // Check to see if this first directory contains the executable...
81    SmallString<128> FilePath(Path);
82    sys::path::append(FilePath, Name);
83    if (sys::fs::can_execute(FilePath.c_str()))
84      return std::string(FilePath.str()); // Found the executable!
85  }
86  return std::errc::no_such_file_or_directory;
87}
88
89static bool RedirectIO(const StringRef *Path, int FD, std::string* ErrMsg) {
90  if (!Path) // Noop
91    return false;
92  std::string File;
93  if (Path->empty())
94    // Redirect empty paths to /dev/null
95    File = "/dev/null";
96  else
97    File = *Path;
98
99  // Open the file
100  int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
101  if (InFD == -1) {
102    MakeErrMsg(ErrMsg, "Cannot open file '" + File + "' for "
103              + (FD == 0 ? "input" : "output"));
104    return true;
105  }
106
107  // Install it as the requested FD
108  if (dup2(InFD, FD) == -1) {
109    MakeErrMsg(ErrMsg, "Cannot dup2");
110    close(InFD);
111    return true;
112  }
113  close(InFD);      // Close the original FD
114  return false;
115}
116
117#ifdef HAVE_POSIX_SPAWN
118static bool RedirectIO_PS(const std::string *Path, int FD, std::string *ErrMsg,
119                          posix_spawn_file_actions_t *FileActions) {
120  if (!Path) // Noop
121    return false;
122  const char *File;
123  if (Path->empty())
124    // Redirect empty paths to /dev/null
125    File = "/dev/null";
126  else
127    File = Path->c_str();
128
129  if (int Err = posix_spawn_file_actions_addopen(
130          FileActions, FD, File,
131          FD == 0 ? O_RDONLY : O_WRONLY | O_CREAT, 0666))
132    return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
133  return false;
134}
135#endif
136
137static void TimeOutHandler(int Sig) {
138}
139
140static void SetMemoryLimits (unsigned size)
141{
142#if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
143  struct rlimit r;
144  __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
145
146  // Heap size
147  getrlimit (RLIMIT_DATA, &r);
148  r.rlim_cur = limit;
149  setrlimit (RLIMIT_DATA, &r);
150#ifdef RLIMIT_RSS
151  // Resident set size.
152  getrlimit (RLIMIT_RSS, &r);
153  r.rlim_cur = limit;
154  setrlimit (RLIMIT_RSS, &r);
155#endif
156#ifdef RLIMIT_AS  // e.g. NetBSD doesn't have it.
157  // Don't set virtual memory limit if built with any Sanitizer. They need 80Tb
158  // of virtual memory for shadow memory mapping.
159#if !LLVM_MEMORY_SANITIZER_BUILD && !LLVM_ADDRESS_SANITIZER_BUILD
160  // Virtual memory.
161  getrlimit (RLIMIT_AS, &r);
162  r.rlim_cur = limit;
163  setrlimit (RLIMIT_AS, &r);
164#endif
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 !defined(__APPLE__) || defined(TARGET_OS_IPHONE)
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#ifdef HAVE_SYS_WAIT_H
317  struct sigaction Act, Old;
318  assert(PI.Pid && "invalid pid to wait on, process not started?");
319
320  int WaitPidOptions = 0;
321  pid_t ChildPid = PI.Pid;
322  if (WaitUntilTerminates) {
323    SecondsToWait = 0;
324  } else if (SecondsToWait) {
325    // Install a timeout handler.  The handler itself does nothing, but the
326    // simple fact of having a handler at all causes the wait below to return
327    // with EINTR, unlike if we used SIG_IGN.
328    memset(&Act, 0, sizeof(Act));
329    Act.sa_handler = TimeOutHandler;
330    sigemptyset(&Act.sa_mask);
331    sigaction(SIGALRM, &Act, &Old);
332    alarm(SecondsToWait);
333  } else if (SecondsToWait == 0)
334    WaitPidOptions = WNOHANG;
335
336  // Parent process: Wait for the child process to terminate.
337  int status;
338  ProcessInfo WaitResult;
339
340  do {
341    WaitResult.Pid = waitpid(ChildPid, &status, WaitPidOptions);
342  } while (WaitUntilTerminates && WaitResult.Pid == -1 && errno == EINTR);
343
344  if (WaitResult.Pid != PI.Pid) {
345    if (WaitResult.Pid == 0) {
346      // Non-blocking wait.
347      return WaitResult;
348    } else {
349      if (SecondsToWait && errno == EINTR) {
350        // Kill the child.
351        kill(PI.Pid, SIGKILL);
352
353        // Turn off the alarm and restore the signal handler
354        alarm(0);
355        sigaction(SIGALRM, &Old, nullptr);
356
357        // Wait for child to die
358        if (wait(&status) != ChildPid)
359          MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
360        else
361          MakeErrMsg(ErrMsg, "Child timed out", 0);
362
363        WaitResult.ReturnCode = -2; // Timeout detected
364        return WaitResult;
365      } else if (errno != EINTR) {
366        MakeErrMsg(ErrMsg, "Error waiting for child process");
367        WaitResult.ReturnCode = -1;
368        return WaitResult;
369      }
370    }
371  }
372
373  // We exited normally without timeout, so turn off the timer.
374  if (SecondsToWait && !WaitUntilTerminates) {
375    alarm(0);
376    sigaction(SIGALRM, &Old, nullptr);
377  }
378
379  // Return the proper exit status. Detect error conditions
380  // so we can return -1 for them and set ErrMsg informatively.
381  int result = 0;
382  if (WIFEXITED(status)) {
383    result = WEXITSTATUS(status);
384    WaitResult.ReturnCode = result;
385
386    if (result == 127) {
387      if (ErrMsg)
388        *ErrMsg = llvm::sys::StrError(ENOENT);
389      WaitResult.ReturnCode = -1;
390      return WaitResult;
391    }
392    if (result == 126) {
393      if (ErrMsg)
394        *ErrMsg = "Program could not be executed";
395      WaitResult.ReturnCode = -1;
396      return WaitResult;
397    }
398  } else if (WIFSIGNALED(status)) {
399    if (ErrMsg) {
400      *ErrMsg = strsignal(WTERMSIG(status));
401#ifdef WCOREDUMP
402      if (WCOREDUMP(status))
403        *ErrMsg += " (core dumped)";
404#endif
405    }
406    // Return a special value to indicate that the process received an unhandled
407    // signal during execution as opposed to failing to execute.
408    WaitResult.ReturnCode = -2;
409  }
410#else
411  if (ErrMsg)
412    *ErrMsg = "Program::Wait is not implemented on this platform yet!";
413  ProcessInfo WaitResult;
414  WaitResult.ReturnCode = -2;
415#endif
416  return WaitResult;
417}
418
419  std::error_code sys::ChangeStdinToBinary(){
420  // Do nothing, as Unix doesn't differentiate between text and binary.
421    return std::error_code();
422}
423
424  std::error_code sys::ChangeStdoutToBinary(){
425  // Do nothing, as Unix doesn't differentiate between text and binary.
426    return std::error_code();
427}
428
429std::error_code
430llvm::sys::writeFileWithEncoding(StringRef FileName, StringRef Contents,
431                                 WindowsEncodingMethod Encoding /*unused*/) {
432  std::error_code EC;
433  llvm::raw_fd_ostream OS(FileName, EC, llvm::sys::fs::OpenFlags::F_Text);
434
435  if (EC)
436    return EC;
437
438  OS << Contents;
439
440  if (OS.has_error())
441    return std::make_error_code(std::errc::io_error);
442
443  return EC;
444}
445
446bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef<const char*> Args) {
447  static long ArgMax = sysconf(_SC_ARG_MAX);
448
449  // System says no practical limit.
450  if (ArgMax == -1)
451    return true;
452
453  // Conservatively account for space required by environment variables.
454  long HalfArgMax = ArgMax / 2;
455
456  size_t ArgLength = 0;
457  for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
458       I != E; ++I) {
459    ArgLength += strlen(*I) + 1;
460    if (ArgLength > size_t(HalfArgMax)) {
461      return false;
462    }
463  }
464  return true;
465}
466}
467