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/Support/Compiler.h"
21#include "llvm/Support/FileSystem.h"
22#include <llvm/Config/config.h>
23#if HAVE_SYS_STAT_H
24#include <sys/stat.h>
25#endif
26#if HAVE_SYS_RESOURCE_H
27#include <sys/resource.h>
28#endif
29#if HAVE_SIGNAL_H
30#include <signal.h>
31#endif
32#if HAVE_FCNTL_H
33#include <fcntl.h>
34#endif
35#ifdef HAVE_POSIX_SPAWN
36#include <spawn.h>
37#if !defined(__APPLE__)
38  extern char **environ;
39#else
40#include <crt_externs.h> // _NSGetEnviron
41#endif
42#endif
43
44namespace llvm {
45using namespace sys;
46
47Program::Program() : Data_(0) {}
48
49Program::~Program() {}
50
51// This function just uses the PATH environment variable to find the program.
52Path
53Program::FindProgramByName(const std::string& progName) {
54
55  // Check some degenerate cases
56  if (progName.length() == 0) // no program
57    return Path();
58  Path temp;
59  if (!temp.set(progName)) // invalid name
60    return Path();
61  // Use the given path verbatim if it contains any slashes; this matches
62  // the behavior of sh(1) and friends.
63  if (progName.find('/') != std::string::npos)
64    return temp;
65
66  // At this point, the file name is valid and does not contain slashes. Search
67  // for it through the directories specified in the PATH environment variable.
68
69  // Get the path. If its empty, we can't do anything to find it.
70  const char *PathStr = getenv("PATH");
71  if (PathStr == 0)
72    return Path();
73
74  // Now we have a colon separated list of directories to search; try them.
75  size_t PathLen = strlen(PathStr);
76  while (PathLen) {
77    // Find the first colon...
78    const char *Colon = std::find(PathStr, PathStr+PathLen, ':');
79
80    // Check to see if this first directory contains the executable...
81    Path FilePath;
82    if (FilePath.set(std::string(PathStr,Colon))) {
83      FilePath.appendComponent(progName);
84      if (FilePath.canExecute())
85        return FilePath;                    // Found the executable!
86    }
87
88    // Nope it wasn't in this directory, check the next path in the list!
89    PathLen -= Colon-PathStr;
90    PathStr = Colon;
91
92    // Advance past duplicate colons
93    while (*PathStr == ':') {
94      PathStr++;
95      PathLen--;
96    }
97  }
98  return Path();
99}
100
101static bool RedirectIO(const Path *Path, int FD, std::string* ErrMsg) {
102  if (Path == 0) // Noop
103    return false;
104  const char *File;
105  if (Path->isEmpty())
106    // Redirect empty paths to /dev/null
107    File = "/dev/null";
108  else
109    File = Path->c_str();
110
111  // Open the file
112  int InFD = open(File, FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
113  if (InFD == -1) {
114    MakeErrMsg(ErrMsg, "Cannot open file '" + std::string(File) + "' for "
115              + (FD == 0 ? "input" : "output"));
116    return true;
117  }
118
119  // Install it as the requested FD
120  if (dup2(InFD, FD) == -1) {
121    MakeErrMsg(ErrMsg, "Cannot dup2");
122    close(InFD);
123    return true;
124  }
125  close(InFD);      // Close the original FD
126  return false;
127}
128
129#ifdef HAVE_POSIX_SPAWN
130static bool RedirectIO_PS(const Path *Path, int FD, std::string *ErrMsg,
131                          posix_spawn_file_actions_t *FileActions) {
132  if (Path == 0) // Noop
133    return false;
134  const char *File;
135  if (Path->isEmpty())
136    // Redirect empty paths to /dev/null
137    File = "/dev/null";
138  else
139    File = Path->c_str();
140
141  if (int Err = posix_spawn_file_actions_addopen(FileActions, FD,
142                            File, FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666))
143    return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
144  return false;
145}
146#endif
147
148static void TimeOutHandler(int Sig) {
149}
150
151static void SetMemoryLimits (unsigned size)
152{
153#if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
154  struct rlimit r;
155  __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
156
157  // Heap size
158  getrlimit (RLIMIT_DATA, &r);
159  r.rlim_cur = limit;
160  setrlimit (RLIMIT_DATA, &r);
161#ifdef RLIMIT_RSS
162  // Resident set size.
163  getrlimit (RLIMIT_RSS, &r);
164  r.rlim_cur = limit;
165  setrlimit (RLIMIT_RSS, &r);
166#endif
167#ifdef RLIMIT_AS  // e.g. NetBSD doesn't have it.
168  // Don't set virtual memory limit if built with any Sanitizer. They need 80Tb
169  // of virtual memory for shadow memory mapping.
170#if !LLVM_MEMORY_SANITIZER_BUILD && !LLVM_ADDRESS_SANITIZER_BUILD
171  // Virtual memory.
172  getrlimit (RLIMIT_AS, &r);
173  r.rlim_cur = limit;
174  setrlimit (RLIMIT_AS, &r);
175#endif
176#endif
177#endif
178}
179
180bool
181Program::Execute(const Path &path, const char **args, const char **envp,
182                 const Path **redirects, unsigned memoryLimit,
183                  std::string *ErrMsg) {
184  // If this OS has posix_spawn and there is no memory limit being implied, use
185  // posix_spawn.  It is more efficient than fork/exec.
186#ifdef HAVE_POSIX_SPAWN
187  if (memoryLimit == 0) {
188    posix_spawn_file_actions_t FileActionsStore;
189    posix_spawn_file_actions_t *FileActions = 0;
190
191    if (redirects) {
192      FileActions = &FileActionsStore;
193      posix_spawn_file_actions_init(FileActions);
194
195      // Redirect stdin/stdout.
196      if (RedirectIO_PS(redirects[0], 0, ErrMsg, FileActions) ||
197          RedirectIO_PS(redirects[1], 1, ErrMsg, FileActions))
198        return false;
199      if (redirects[1] == 0 || redirects[2] == 0 ||
200          *redirects[1] != *redirects[2]) {
201        // Just redirect stderr
202        if (RedirectIO_PS(redirects[2], 2, ErrMsg, FileActions)) return false;
203      } else {
204        // If stdout and stderr should go to the same place, redirect stderr
205        // to the FD already open for stdout.
206        if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
207          return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
208      }
209    }
210
211    if (!envp)
212#if !defined(__APPLE__)
213      envp = const_cast<const char **>(environ);
214#else
215      // environ is missing in dylibs.
216      envp = const_cast<const char **>(*_NSGetEnviron());
217#endif
218
219    // Explicitly initialized to prevent what appears to be a valgrind false
220    // positive.
221    pid_t PID = 0;
222    int Err = posix_spawn(&PID, path.c_str(), FileActions, /*attrp*/0,
223                          const_cast<char **>(args), const_cast<char **>(envp));
224
225    if (FileActions)
226      posix_spawn_file_actions_destroy(FileActions);
227
228    if (Err)
229     return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
230
231    Data_ = reinterpret_cast<void*>(PID);
232    return true;
233  }
234#endif
235
236  // Create a child process.
237  int child = fork();
238  switch (child) {
239    // An error occurred:  Return to the caller.
240    case -1:
241      MakeErrMsg(ErrMsg, "Couldn't fork");
242      return false;
243
244    // Child process: Execute the program.
245    case 0: {
246      // Redirect file descriptors...
247      if (redirects) {
248        // Redirect stdin
249        if (RedirectIO(redirects[0], 0, ErrMsg)) { return false; }
250        // Redirect stdout
251        if (RedirectIO(redirects[1], 1, ErrMsg)) { return false; }
252        if (redirects[1] && redirects[2] &&
253            *(redirects[1]) == *(redirects[2])) {
254          // If stdout and stderr should go to the same place, redirect stderr
255          // to the FD already open for stdout.
256          if (-1 == dup2(1,2)) {
257            MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
258            return false;
259          }
260        } else {
261          // Just redirect stderr
262          if (RedirectIO(redirects[2], 2, ErrMsg)) { return false; }
263        }
264      }
265
266      // Set memory limits
267      if (memoryLimit!=0) {
268        SetMemoryLimits(memoryLimit);
269      }
270
271      // Execute!
272      if (envp != 0)
273        execve(path.c_str(),
274               const_cast<char **>(args),
275               const_cast<char **>(envp));
276      else
277        execv(path.c_str(),
278              const_cast<char **>(args));
279      // If the execve() failed, we should exit. Follow Unix protocol and
280      // return 127 if the executable was not found, and 126 otherwise.
281      // Use _exit rather than exit so that atexit functions and static
282      // object destructors cloned from the parent process aren't
283      // redundantly run, and so that any data buffered in stdio buffers
284      // cloned from the parent aren't redundantly written out.
285      _exit(errno == ENOENT ? 127 : 126);
286    }
287
288    // Parent process: Break out of the switch to do our processing.
289    default:
290      break;
291  }
292
293  Data_ = reinterpret_cast<void*>(child);
294
295  return true;
296}
297
298int
299Program::Wait(const sys::Path &path,
300              unsigned secondsToWait,
301              std::string* ErrMsg)
302{
303#ifdef HAVE_SYS_WAIT_H
304  struct sigaction Act, Old;
305
306  if (Data_ == 0) {
307    MakeErrMsg(ErrMsg, "Process not started!");
308    return -1;
309  }
310
311  // Install a timeout handler.  The handler itself does nothing, but the simple
312  // fact of having a handler at all causes the wait below to return with EINTR,
313  // unlike if we used SIG_IGN.
314  if (secondsToWait) {
315    memset(&Act, 0, sizeof(Act));
316    Act.sa_handler = TimeOutHandler;
317    sigemptyset(&Act.sa_mask);
318    sigaction(SIGALRM, &Act, &Old);
319    alarm(secondsToWait);
320  }
321
322  // Parent process: Wait for the child process to terminate.
323  int status;
324  uint64_t pid = reinterpret_cast<uint64_t>(Data_);
325  pid_t child = static_cast<pid_t>(pid);
326  while (waitpid(pid, &status, 0) != child)
327    if (secondsToWait && errno == EINTR) {
328      // Kill the child.
329      kill(child, SIGKILL);
330
331      // Turn off the alarm and restore the signal handler
332      alarm(0);
333      sigaction(SIGALRM, &Old, 0);
334
335      // Wait for child to die
336      if (wait(&status) != child)
337        MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
338      else
339        MakeErrMsg(ErrMsg, "Child timed out", 0);
340
341      return -2;   // Timeout detected
342    } else if (errno != EINTR) {
343      MakeErrMsg(ErrMsg, "Error waiting for child process");
344      return -1;
345    }
346
347  // We exited normally without timeout, so turn off the timer.
348  if (secondsToWait) {
349    alarm(0);
350    sigaction(SIGALRM, &Old, 0);
351  }
352
353  // Return the proper exit status. Detect error conditions
354  // so we can return -1 for them and set ErrMsg informatively.
355  int result = 0;
356  if (WIFEXITED(status)) {
357    result = WEXITSTATUS(status);
358#ifdef HAVE_POSIX_SPAWN
359    // The posix_spawn child process returns 127 on any kind of error.
360    // Following the POSIX convention for command-line tools (which posix_spawn
361    // itself apparently does not), check to see if the failure was due to some
362    // reason other than the file not existing, and return 126 in this case.
363    bool Exists;
364    if (result == 127 && !llvm::sys::fs::exists(path.str(), Exists) && Exists)
365      result = 126;
366#endif
367    if (result == 127) {
368      if (ErrMsg)
369        *ErrMsg = llvm::sys::StrError(ENOENT);
370      return -1;
371    }
372    if (result == 126) {
373      if (ErrMsg)
374        *ErrMsg = "Program could not be executed";
375      return -1;
376    }
377  } else if (WIFSIGNALED(status)) {
378    if (ErrMsg) {
379      *ErrMsg = strsignal(WTERMSIG(status));
380#ifdef WCOREDUMP
381      if (WCOREDUMP(status))
382        *ErrMsg += " (core dumped)";
383#endif
384    }
385    // Return a special value to indicate that the process received an unhandled
386    // signal during execution as opposed to failing to execute.
387    return -2;
388  }
389  return result;
390#else
391  if (ErrMsg)
392    *ErrMsg = "Program::Wait is not implemented on this platform yet!";
393  return -1;
394#endif
395}
396
397error_code Program::ChangeStdinToBinary(){
398  // Do nothing, as Unix doesn't differentiate between text and binary.
399  return make_error_code(errc::success);
400}
401
402error_code Program::ChangeStdoutToBinary(){
403  // Do nothing, as Unix doesn't differentiate between text and binary.
404  return make_error_code(errc::success);
405}
406
407error_code Program::ChangeStderrToBinary(){
408  // Do nothing, as Unix doesn't differentiate between text and binary.
409  return make_error_code(errc::success);
410}
411
412}
413