src/llvm/lib/Support/Unix/Program.inc

   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 <llvm/Config/config.h>
  20 #include "llvm/Support/FileSystem.h"
  21 #include "Unix.h"
  22 #if HAVE_SYS_STAT_H
  23 #include <sys/stat.h>
  24 #endif
  25 #if HAVE_SYS_RESOURCE_H
  26 #include <sys/resource.h>
  27 #endif
  28 #if HAVE_SIGNAL_H
  29 #include <signal.h>
  30 #endif
  31 #if HAVE_FCNTL_H
  32 #include <fcntl.h>
  33 #endif
  34 #ifdef HAVE_POSIX_SPAWN
  35 #include <spawn.h>
  36 #if !defined(__APPLE__)
  37   extern char **environ;
  38 #else
  39 #include <crt_externs.h> // _NSGetEnviron
  40 #endif
  41 #endif
  42
  43 namespace llvm {
  44 using namespace sys;
  45
  46 Program::Program() : Data_(0) {}
  47
  48 Program::~Program() {}
  49
  50 unsigned Program::GetPid() const {
  51   uint64_t pid = reinterpret_cast<uint64_t>(Data_);
  52   return static_cast<unsigned>(pid);
  53 }
  54
  55 // This function just uses the PATH environment variable to find the program.
  56 Path
  57 Program::FindProgramByName(const std::string& progName) {
  58
  59   // Check some degenerate cases
  60   if (progName.length() == 0) // no program
  61     return Path();
  62   Path temp;
  63   if (!temp.set(progName)) // invalid name
  64     return Path();
  65   // Use the given path verbatim if it contains any slashes; this matches
  66   // the behavior of sh(1) and friends.
  67   if (progName.find('/') != std::string::npos)
  68     return temp;
  69
  70   // At this point, the file name is valid and does not contain slashes. Search
  71   // for it through the directories specified in the PATH environment variable.
  72
  73   // Get the path. If its empty, we can't do anything to find it.
  74   const char *PathStr = getenv("PATH");
  75   if (PathStr == 0)
  76     return Path();
  77
  78   // Now we have a colon separated list of directories to search; try them.
  79   size_t PathLen = strlen(PathStr);
  80   while (PathLen) {
  81     // Find the first colon...
  82     const char *Colon = std::find(PathStr, PathStr+PathLen, ':');
  83
  84     // Check to see if this first directory contains the executable...
  85     Path FilePath;
  86     if (FilePath.set(std::string(PathStr,Colon))) {
  87       FilePath.appendComponent(progName);
  88       if (FilePath.canExecute())
  89         return FilePath;                    // Found the executable!
  90     }
  91
  92     // Nope it wasn't in this directory, check the next path in the list!
  93     PathLen -= Colon-PathStr;
  94     PathStr = Colon;
  95
  96     // Advance past duplicate colons
  97     while (*PathStr == ':') {
  98       PathStr++;
  99       PathLen--;
 100     }
 101   }
 102   return Path();
 103 }
 104
 105 static bool RedirectIO(const Path *Path, int FD, std::string* ErrMsg) {
 106   if (Path == 0) // Noop
 107     return false;
 108   const char *File;
 109   if (Path->isEmpty())
 110     // Redirect empty paths to /dev/null
 111     File = "/dev/null";
 112   else
 113     File = Path->c_str();
 114
 115   // Open the file
 116   int InFD = open(File, FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
 117   if (InFD == -1) {
 118     MakeErrMsg(ErrMsg, "Cannot open file '" + std::string(File) + "' for "
 119               + (FD == 0 ? "input" : "output"));
 120     return true;
 121   }
 122
 123   // Install it as the requested FD
 124   if (dup2(InFD, FD) == -1) {
 125     MakeErrMsg(ErrMsg, "Cannot dup2");
 126     close(InFD);
 127     return true;
 128   }
 129   close(InFD);      // Close the original FD
 130   return false;
 131 }
 132
 133 #ifdef HAVE_POSIX_SPAWN
 134 static bool RedirectIO_PS(const Path *Path, int FD, std::string *ErrMsg,
 135                           posix_spawn_file_actions_t *FileActions) {
 136   if (Path == 0) // Noop
 137     return false;
 138   const char *File;
 139   if (Path->isEmpty())
 140     // Redirect empty paths to /dev/null
 141     File = "/dev/null";
 142   else
 143     File = Path->c_str();
 144
 145   if (int Err = posix_spawn_file_actions_addopen(FileActions, FD,
 146                             File, FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666))
 147     return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
 148   return false;
 149 }
 150 #endif
 151
 152 static void TimeOutHandler(int Sig) {
 153 }
 154
 155 static void SetMemoryLimits (unsigned size)
 156 {
 157 #if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
 158   struct rlimit r;
 159   __typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
 160
 161   // Heap size
 162   getrlimit (RLIMIT_DATA, &r);
 163   r.rlim_cur = limit;
 164   setrlimit (RLIMIT_DATA, &r);
 165 #ifdef RLIMIT_RSS
 166   // Resident set size.
 167   getrlimit (RLIMIT_RSS, &r);
 168   r.rlim_cur = limit;
 169   setrlimit (RLIMIT_RSS, &r);
 170 #endif
 171 #ifdef RLIMIT_AS  // e.g. NetBSD doesn't have it.
 172   // Virtual memory.
 173   getrlimit (RLIMIT_AS, &r);
 174   r.rlim_cur = limit;
 175   setrlimit (RLIMIT_AS, &r);
 176 #endif
 177 #endif
 178 }
 179
 180 bool
 181 Program::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
 298 int
 299 Program::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
 397 bool
 398 Program::Kill(std::string* ErrMsg) {
 399   if (Data_ == 0) {
 400     MakeErrMsg(ErrMsg, "Process not started!");
 401     return true;
 402   }
 403
 404   uint64_t pid64 = reinterpret_cast<uint64_t>(Data_);
 405   pid_t pid = static_cast<pid_t>(pid64);
 406
 407   if (kill(pid, SIGKILL) != 0) {
 408     MakeErrMsg(ErrMsg, "The process couldn't be killed!");
 409     return true;
 410   }
 411
 412   return false;
 413 }
 414
 415 error_code Program::ChangeStdinToBinary(){
 416   // Do nothing, as Unix doesn't differentiate between text and binary.
 417   return make_error_code(errc::success);
 418 }
 419
 420 error_code Program::ChangeStdoutToBinary(){
 421   // Do nothing, as Unix doesn't differentiate between text and binary.
 422   return make_error_code(errc::success);
 423 }
 424
 425 error_code Program::ChangeStderrToBinary(){
 426   // Do nothing, as Unix doesn't differentiate between text and binary.
 427   return make_error_code(errc::success);
 428 }
 429
 430 }