ProcessUNIX.c

/*============================================================================
  KWSys - Kitware System Library
  Copyright 2000-2009 Kitware, Inc., Insight Software Consortium

  Distributed under the OSI-approved BSD License (the "License");
  see accompanying file Copyright.txt for details.

  This software is distributed WITHOUT ANY WARRANTY; without even the
  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  See the License for more information.
============================================================================*/
#include "kwsysPrivate.h"
#include KWSYS_HEADER(Process.h)
#include KWSYS_HEADER(System.h)

/* Work-around CMake dependency scanning limitation.  This must
   duplicate the above list of headers.  */
#if 0
# include "Process.h.in"
# include "System.h.in"
#endif

/*

Implementation for UNIX

On UNIX, a child process is forked to exec the program.  Three output
pipes are read by the parent process using a select call to block
until data are ready.  Two of the pipes are stdout and stderr for the
child.  The third is a special pipe populated by a signal handler to
indicate that a child has terminated.  This is used in conjunction
with the timeout on the select call to implement a timeout for program
even when it closes stdout and stderr and at the same time avoiding
races.

*/


/*

TODO:

We cannot create the pipeline of processes in suspended states.  How
do we cleanup processes already started when one fails to load?  Right
now we are just killing them, which is probably not the right thing to
do.

*/

#include <stddef.h>    /* ptrdiff_t */
#include <stdio.h>     /* snprintf */
#include <stdlib.h>    /* malloc, free */
#include <string.h>    /* strdup, strerror, memset */
#include <sys/time.h>  /* struct timeval */
#include <sys/types.h> /* pid_t, fd_set */
#include <sys/wait.h>  /* waitpid */
#include <sys/stat.h>  /* open mode */
#include <unistd.h>    /* pipe, close, fork, execvp, select, _exit */
#include <fcntl.h>     /* fcntl */
#include <errno.h>     /* errno */
#include <time.h>      /* gettimeofday */
#include <signal.h>    /* sigaction */
#include <dirent.h>    /* DIR, dirent */
#include <ctype.h>     /* isspace */

#ifdef __HAIKU__
#undef __BEOS__
#endif

#if defined(__VMS)
# define KWSYSPE_VMS_NONBLOCK , O_NONBLOCK
#else
# define KWSYSPE_VMS_NONBLOCK
#endif

#if defined(KWSYS_C_HAS_PTRDIFF_T) && KWSYS_C_HAS_PTRDIFF_T
typedef ptrdiff_t kwsysProcess_ptrdiff_t;
#else
typedef int kwsysProcess_ptrdiff_t;
#endif

#if defined(KWSYS_C_HAS_SSIZE_T) && KWSYS_C_HAS_SSIZE_T
typedef ssize_t kwsysProcess_ssize_t;
#else
typedef int kwsysProcess_ssize_t;
#endif

#if defined(__BEOS__) && !defined(__ZETA__) 
/* BeOS 5 doesn't have usleep(), but it has snooze(), which is identical. */
# include <be/kernel/OS.h>
static inline void kwsysProcess_usleep(unsigned int msec)
{
  snooze(msec);
}
#else
# define kwsysProcess_usleep usleep
#endif

/*
 * BeOS's select() works like WinSock: it's for networking only, and
 * doesn't work with Unix file handles...socket and file handles are
 * different namespaces (the same descriptor means different things in
 * each context!)
 *
 * So on Unix-like systems where select() is flakey, we'll set the
 * pipes' file handles to be non-blocking and just poll them directly
 * without select().
 */
#if !defined(__BEOS__) && !defined(__VMS)
# define KWSYSPE_USE_SELECT 1
#endif

/* Some platforms do not have siginfo on their signal handlers.  */
#if defined(SA_SIGINFO) && !defined(__BEOS__)
# define KWSYSPE_USE_SIGINFO 1
#endif

/* The number of pipes for the child's output.  The standard stdout
   and stderr pipes are the first two.  One more pipe is used to
   detect when the child process has terminated.  The third pipe is
   not given to the child process, so it cannot close it until it
   terminates.  */
#define KWSYSPE_PIPE_COUNT 3
#define KWSYSPE_PIPE_STDOUT 0
#define KWSYSPE_PIPE_STDERR 1
#define KWSYSPE_PIPE_SIGNAL 2

/* The maximum amount to read from a pipe at a time.  */
#define KWSYSPE_PIPE_BUFFER_SIZE 1024

/* Keep track of times using a signed representation.  Switch to the
   native (possibly unsigned) representation only when calling native
   functions.  */
typedef struct timeval kwsysProcessTimeNative;
typedef struct kwsysProcessTime_s kwsysProcessTime;
struct kwsysProcessTime_s
{
  long tv_sec;
  long tv_usec;
};

typedef struct kwsysProcessCreateInformation_s
{
  int StdIn;
  int StdOut;
  int StdErr;
  int ErrorPipe[2];
} kwsysProcessCreateInformation;

/*--------------------------------------------------------------------------*/
static int kwsysProcessInitialize(kwsysProcess* cp);
static void kwsysProcessCleanup(kwsysProcess* cp, int error);
static void kwsysProcessCleanupDescriptor(int* pfd);
static void kwsysProcessClosePipes(kwsysProcess* cp);
static int kwsysProcessSetNonBlocking(int fd);
static int kwsysProcessCreate(kwsysProcess* cp, int prIndex,
                              kwsysProcessCreateInformation* si, int* readEnd);
static void kwsysProcessDestroy(kwsysProcess* cp);
static int kwsysProcessSetupOutputPipeFile(int* p, const char* name);
static int kwsysProcessSetupOutputPipeNative(int* p, int des[2]);
static int kwsysProcessGetTimeoutTime(kwsysProcess* cp, double* userTimeout,
                                      kwsysProcessTime* timeoutTime);
static int kwsysProcessGetTimeoutLeft(kwsysProcessTime* timeoutTime,
                                      double* userTimeout,
                                      kwsysProcessTimeNative* timeoutLength,
                                      int zeroIsExpired);
static kwsysProcessTime kwsysProcessTimeGetCurrent(void);
static double kwsysProcessTimeToDouble(kwsysProcessTime t);
static kwsysProcessTime kwsysProcessTimeFromDouble(double d);
static int kwsysProcessTimeLess(kwsysProcessTime in1, kwsysProcessTime in2);
static kwsysProcessTime kwsysProcessTimeAdd(kwsysProcessTime in1, kwsysProcessTime in2);
static kwsysProcessTime kwsysProcessTimeSubtract(kwsysProcessTime in1, kwsysProcessTime in2);
static void kwsysProcessSetExitException(kwsysProcess* cp, int sig);
static void kwsysProcessChildErrorExit(int errorPipe);
static void kwsysProcessRestoreDefaultSignalHandlers(void);
static pid_t kwsysProcessFork(kwsysProcess* cp,
                              kwsysProcessCreateInformation* si);
static void kwsysProcessKill(pid_t process_id);
#if defined(__VMS)
static int kwsysProcessSetVMSFeature(const char* name, int value);
#endif
static int kwsysProcessesAdd(kwsysProcess* cp);
static void kwsysProcessesRemove(kwsysProcess* cp);
#if KWSYSPE_USE_SIGINFO
static void kwsysProcessesSignalHandler(int signum, siginfo_t* info,
                                        void* ucontext);
#else
static void kwsysProcessesSignalHandler(int signum);
#endif

/*--------------------------------------------------------------------------*/
/* Structure containing data used to implement the child's execution.  */
struct kwsysProcess_s
{
  /* The command lines to execute.  */
  char*** Commands;
  int NumberOfCommands;

  /* Descriptors for the read ends of the child's output pipes and
     the signal pipe. */
  int PipeReadEnds[KWSYSPE_PIPE_COUNT];

  /* Write descriptor for child termination signal pipe.  */
  int SignalPipe;

  /* Buffer for pipe data.  */
  char PipeBuffer[KWSYSPE_PIPE_BUFFER_SIZE];

  /* Process IDs returned by the calls to fork.  */
  pid_t* ForkPIDs;

  /* Flag for whether the children were terminated by a faild select.  */
  int SelectError;

  /* The timeout length.  */
  double Timeout;

  /* The working directory for the process. */
  char* WorkingDirectory;

  /* Whether to create the child as a detached process.  */
  int OptionDetach;

  /* Whether the child was created as a detached process.  */
  int Detached;

  /* Whether to treat command lines as verbatim.  */
  int Verbatim;

  /* Time at which the child started.  Negative for no timeout.  */
  kwsysProcessTime StartTime;

  /* Time at which the child will timeout.  Negative for no timeout.  */
  kwsysProcessTime TimeoutTime;

  /* Flag for whether the timeout expired.  */
  int TimeoutExpired;

  /* The number of pipes left open during execution.  */
  int PipesLeft;

#if KWSYSPE_USE_SELECT
  /* File descriptor set for call to select.  */
  fd_set PipeSet;
#endif

  /* The number of children still executing.  */
  int CommandsLeft;

  /* The current status of the child process. */
  int State;

  /* The exceptional behavior that terminated the child process, if
   * any.  */
  int ExitException;

  /* The exit code of the child process.  */
  int ExitCode;

  /* The exit value of the child process, if any.  */
  int ExitValue;

  /* Whether the process was killed.  */
  int Killed;

  /* Buffer for error message in case of failure.  */
  char ErrorMessage[KWSYSPE_PIPE_BUFFER_SIZE+1];

  /* Description for the ExitException.  */
  char ExitExceptionString[KWSYSPE_PIPE_BUFFER_SIZE+1];

  /* The exit codes of each child process in the pipeline.  */
  int* CommandExitCodes;

  /* Name of files to which stdin and stdout pipes are attached.  */
  char* PipeFileSTDIN;
  char* PipeFileSTDOUT;
  char* PipeFileSTDERR;

  /* Whether each pipe is shared with the parent process.  */
  int PipeSharedSTDIN;
  int PipeSharedSTDOUT;
  int PipeSharedSTDERR;

  /* Native pipes provided by the user.  */
  int PipeNativeSTDIN[2];
  int PipeNativeSTDOUT[2];
  int PipeNativeSTDERR[2];

  /* The real working directory of this process.  */
  int RealWorkingDirectoryLength;
  char* RealWorkingDirectory;
};

/*--------------------------------------------------------------------------*/
kwsysProcess* kwsysProcess_New(void)
{
  /* Allocate a process control structure.  */
  kwsysProcess* cp = (kwsysProcess*)malloc(sizeof(kwsysProcess));
  if(!cp)
    {
    return 0;
    }
  memset(cp, 0, sizeof(kwsysProcess));

  /* Share stdin with the parent process by default.  */
  cp->PipeSharedSTDIN = 1;

  /* No native pipes by default.  */
  cp->PipeNativeSTDIN[0] = -1;
  cp->PipeNativeSTDIN[1] = -1;
  cp->PipeNativeSTDOUT[0] = -1;
  cp->PipeNativeSTDOUT[1] = -1;
  cp->PipeNativeSTDERR[0] = -1;
  cp->PipeNativeSTDERR[1] = -1;

  /* Set initial status.  */
  cp->State = kwsysProcess_State_Starting;

  return cp;
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_Delete(kwsysProcess* cp)
{
  /* Make sure we have an instance.  */
  if(!cp)
    {
    return;
    }

  /* If the process is executing, wait for it to finish.  */
  if(cp->State == kwsysProcess_State_Executing)
    {
    if(cp->Detached)
      {
      kwsysProcess_Disown(cp);
      }
    else
      {
      kwsysProcess_WaitForExit(cp, 0);
      }
    }

  /* Free memory.  */
  kwsysProcess_SetCommand(cp, 0);
  kwsysProcess_SetWorkingDirectory(cp, 0);
  kwsysProcess_SetPipeFile(cp, kwsysProcess_Pipe_STDIN, 0);
  kwsysProcess_SetPipeFile(cp, kwsysProcess_Pipe_STDOUT, 0);
  kwsysProcess_SetPipeFile(cp, kwsysProcess_Pipe_STDERR, 0);
  if(cp->CommandExitCodes)
    {
    free(cp->CommandExitCodes);
    }
  free(cp);
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_SetCommand(kwsysProcess* cp, char const* const* command)
{
  int i;
  if(!cp)
    {
    return 0;
    }
  for(i=0; i < cp->NumberOfCommands; ++i)
    {
    char** c = cp->Commands[i];
    while(*c)
      {
      free(*c++);
      }
    free(cp->Commands[i]);
    }
  cp->NumberOfCommands = 0;
  if(cp->Commands)
    {
    free(cp->Commands);
    cp->Commands = 0;
    }
  if(command)
    {
    return kwsysProcess_AddCommand(cp, command);
    }
  return 1;
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_AddCommand(kwsysProcess* cp, char const* const* command)
{
  int newNumberOfCommands;
  char*** newCommands;

  /* Make sure we have a command to add.  */
  if(!cp || !command || !*command)
    {
    return 0;
    }

  /* Allocate a new array for command pointers.  */
  newNumberOfCommands = cp->NumberOfCommands + 1;
  if(!(newCommands =
       (char***)malloc(sizeof(char**) *(size_t)(newNumberOfCommands))))
    {
    /* Out of memory.  */
    return 0;
    }

  /* Copy any existing commands into the new array.  */
  {
  int i;
  for(i=0; i < cp->NumberOfCommands; ++i)
    {
    newCommands[i] = cp->Commands[i];
    }
  }

  /* Add the new command.  */
  if(cp->Verbatim)
    {
    /* In order to run the given command line verbatim we need to
       parse it.  */
    newCommands[cp->NumberOfCommands] =
      kwsysSystem_Parse_CommandForUnix(*command, 0);
    if(!newCommands[cp->NumberOfCommands])
      {
      /* Out of memory.  */
      free(newCommands);
      return 0;
      }
    }
  else
    {
    /* Copy each argument string individually.  */
    char const* const* c = command;
    kwsysProcess_ptrdiff_t n = 0;
    kwsysProcess_ptrdiff_t i = 0;
    while(*c++);
    n = c - command - 1;
    newCommands[cp->NumberOfCommands] =
      (char**)malloc((size_t)(n+1)*sizeof(char*));
    if(!newCommands[cp->NumberOfCommands])
      {
      /* Out of memory.  */
      free(newCommands);
      return 0;
      }
    for(i=0; i < n; ++i)
      {
      newCommands[cp->NumberOfCommands][i] = strdup(command[i]);
      if(!newCommands[cp->NumberOfCommands][i])
        {
        break;
        }
      }
    if(i < n)
      {
      /* Out of memory.  */
      for(;i > 0; --i)
        {
        free(newCommands[cp->NumberOfCommands][i-1]);
        }
      free(newCommands);
      return 0;
      }
    newCommands[cp->NumberOfCommands][n] = 0;
    }

  /* Successfully allocated new command array.  Free the old array. */
  free(cp->Commands);
  cp->Commands = newCommands;
  cp->NumberOfCommands = newNumberOfCommands;

  return 1;
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_SetTimeout(kwsysProcess* cp, double timeout)
{
  if(!cp)
    {
    return;
    }
  cp->Timeout = timeout;
  if(cp->Timeout < 0)
    {
    cp->Timeout = 0;
    }
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_SetWorkingDirectory(kwsysProcess* cp, const char* dir)
{
  if(!cp)
    {
    return 0;
    }
  if(cp->WorkingDirectory == dir)
    {
    return 1;
    }
  if(cp->WorkingDirectory && dir && strcmp(cp->WorkingDirectory, dir) == 0)
    {
    return 1;
    }
  if(cp->WorkingDirectory)
    {
    free(cp->WorkingDirectory);
    cp->WorkingDirectory = 0;
    }
  if(dir)
    {
    cp->WorkingDirectory = (char*)malloc(strlen(dir) + 1);
    if(!cp->WorkingDirectory)
      {
      return 0;
      }
    strcpy(cp->WorkingDirectory, dir);
    }
  return 1;
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_SetPipeFile(kwsysProcess* cp, int prPipe, const char* file)
{
  char** pfile;
  if(!cp)
    {
    return 0;
    }
  switch(prPipe)
    {
    case kwsysProcess_Pipe_STDIN: pfile = &cp->PipeFileSTDIN; break;
    case kwsysProcess_Pipe_STDOUT: pfile = &cp->PipeFileSTDOUT; break;
    case kwsysProcess_Pipe_STDERR: pfile = &cp->PipeFileSTDERR; break;
    default: return 0;
    }
  if(*pfile)
    {
    free(*pfile);
    *pfile = 0;
    }
  if(file)
    {
    *pfile = malloc(strlen(file)+1);
    if(!*pfile)
      {
      return 0;
      }
    strcpy(*pfile, file);
    }

  /* If we are redirecting the pipe, do not share it or use a native
     pipe.  */
  if(*pfile)
    {
    kwsysProcess_SetPipeNative(cp, prPipe, 0);
    kwsysProcess_SetPipeShared(cp, prPipe, 0);
    }
  return 1;
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_SetPipeShared(kwsysProcess* cp, int prPipe, int shared)
{
  if(!cp)
    {
    return;
    }

  switch(prPipe)
    {
    case kwsysProcess_Pipe_STDIN: cp->PipeSharedSTDIN = shared?1:0; break;
    case kwsysProcess_Pipe_STDOUT: cp->PipeSharedSTDOUT = shared?1:0; break;
    case kwsysProcess_Pipe_STDERR: cp->PipeSharedSTDERR = shared?1:0; break;
    default: return;
    }

  /* If we are sharing the pipe, do not redirect it to a file or use a
     native pipe.  */
  if(shared)
    {
    kwsysProcess_SetPipeFile(cp, prPipe, 0);
    kwsysProcess_SetPipeNative(cp, prPipe, 0);
    }
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_SetPipeNative(kwsysProcess* cp, int prPipe, int p[2])
{
  int* pPipeNative = 0;

  if(!cp)
    {
    return;
    }

  switch(prPipe)
    {
    case kwsysProcess_Pipe_STDIN: pPipeNative = cp->PipeNativeSTDIN; break;
    case kwsysProcess_Pipe_STDOUT: pPipeNative = cp->PipeNativeSTDOUT; break;
    case kwsysProcess_Pipe_STDERR: pPipeNative = cp->PipeNativeSTDERR; break;
    default: return;
    }

  /* Copy the native pipe descriptors provided.  */
  if(p)
    {
    pPipeNative[0] = p[0];
    pPipeNative[1] = p[1];
    }
  else
    {
    pPipeNative[0] = -1;
    pPipeNative[1] = -1;
    }

  /* If we are using a native pipe, do not share it or redirect it to
     a file.  */
  if(p)
    {
    kwsysProcess_SetPipeFile(cp, prPipe, 0);
    kwsysProcess_SetPipeShared(cp, prPipe, 0);
    }
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_GetOption(kwsysProcess* cp, int optionId)
{
  if(!cp)
    {
    return 0;
    }

  switch(optionId)
    {
    case kwsysProcess_Option_Detach: return cp->OptionDetach;
    case kwsysProcess_Option_Verbatim: return cp->Verbatim;
    default: return 0;
    }
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_SetOption(kwsysProcess* cp, int optionId, int value)
{
  if(!cp)
    {
    return;
    }

  switch(optionId)
    {
    case kwsysProcess_Option_Detach: cp->OptionDetach = value; break;
    case kwsysProcess_Option_Verbatim: cp->Verbatim = value; break;
    default: break;
    }
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_GetState(kwsysProcess* cp)
{
  return cp? cp->State : kwsysProcess_State_Error;
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_GetExitException(kwsysProcess* cp)
{
  return cp? cp->ExitException : kwsysProcess_Exception_Other;
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_GetExitCode(kwsysProcess* cp)
{
  return cp? cp->ExitCode : 0;
}

/*--------------------------------------------------------------------------*/
int kwsysProcess_GetExitValue(kwsysProcess* cp)
{
  return cp? cp->ExitValue : -1;
}

/*--------------------------------------------------------------------------*/
const char* kwsysProcess_GetErrorString(kwsysProcess* cp)
{
  if(!cp)
    {
    return "Process management structure could not be allocated";
    }
  else if(cp->State == kwsysProcess_State_Error)
    {
    return cp->ErrorMessage;
    }
  return "Success";
}

/*--------------------------------------------------------------------------*/
const char* kwsysProcess_GetExceptionString(kwsysProcess* cp)
{
  if(!cp)
    {
    return "GetExceptionString called with NULL process management structure";
    }
  else if(cp->State == kwsysProcess_State_Exception)
    {
    return cp->ExitExceptionString;
    }
  return "No exception";
}

/*--------------------------------------------------------------------------*/
void kwsysProcess_Execute(kwsysProcess* cp)
{
  int i;
  kwsysProcessCreateInformation si = {-1, -1, -1, {-1, -1}};

  /* Do not execute a second copy simultaneously.  */
  if(!cp || cp->State == kwsysProcess_State_Executing)
    {
    return;
    }

  /* Initialize the control structure for a new process.  */
  if(!kwsysProcessInitialize(cp))
    {
    strcpy(cp->ErrorMessage, "Out of memory");
    cp->State = kwsysProcess_State_Error;
    return;
    }

#if defined(__VMS)
  /* Make sure pipes behave like streams on VMS.  */
  if(!kwsysProcessSetVMSFeature("DECC$STREAM_PIPE", 1))
    {
    kwsysProcessCleanup(cp, 1);
    return;
    }
#endif

  /* Save the real working directory of this process and change to
     the working directory for the child processes.  This is needed
     to make pipe file paths evaluate correctly.  */
  if(cp->WorkingDirectory)
    {
    int r;
    if(!getcwd(cp->RealWorkingDirectory,
               (size_t)(cp->RealWorkingDirectoryLength)))
      {
      kwsysProcessCleanup(cp, 1);
      return;
      }

    /* Some platforms specify that the chdir call may be
       interrupted.  Repeat the call until it finishes.  */
    while(((r = chdir(cp->WorkingDirectory)) < 0) && (errno == EINTR));
    if(r < 0)
      {
      kwsysProcessCleanup(cp, 1);
      return;
      }
    }

  /* If not running a detached child, add this object to the global
     set of process objects that wish to be notified when a child
     exits.  */
  if(!cp->OptionDetach)
    {
    if(!kwsysProcessesAdd(cp))
      {
      kwsysProcessCleanup(cp, 1);
      return;
      }
    }

  /* Setup the stderr pipe to be shared by all processes.  */
  {
  /* Create the pipe.  */
  int p[2];
  if(pipe(p KWSYSPE_VMS_NONBLOCK) < 0)
    {
    kwsysProcessCleanup(cp, 1);
    return;
    }

  /* Store the pipe.  */
  cp->PipeReadEnds[KWSYSPE_PIPE_STDERR] = p[0];
  si.StdErr = p[1];

  /* Set close-on-exec flag on the pipe's ends.  */
  if((fcntl(p[0], F_SETFD, FD_CLOEXEC) < 0) ||
     (fcntl(p[1], F_SETFD, FD_CLOEXEC) < 0))
    {
    kwsysProcessCleanup(cp, 1);
    kwsysProcessCleanupDescriptor(&si.StdErr);
    return;
    }

  /* Set to non-blocking in case select lies, or for the polling
     implementation.  */
  if(!kwsysProcessSetNonBlocking(p[0]))
    {
    kwsysProcessCleanup(cp, 1);
    kwsysProcessCleanupDescriptor(&si.StdErr);
    return;
    }
  }

  /* Replace the stderr pipe with a file if requested.  In this case
     the select call will report that stderr is closed immediately.  */
  if(cp->PipeFileSTDERR)
    {
    if(!kwsysProcessSetupOutputPipeFile(&si.StdErr, cp->PipeFileSTDERR))
      {
      kwsysProcessCleanup(cp, 1);
      kwsysProcessCleanupDescriptor(&si.StdErr);
      return;
      }
    }

  /* Replace the stderr pipe with the parent's if requested.  In this
     case the select call will report that stderr is closed
     immediately.  */
  if(cp->PipeSharedSTDERR)
    {
    kwsysProcessCleanupDescriptor(&si.StdErr);
    si.StdErr = 2;
    }

  /* Replace the stderr pipe with the native pipe provided if any.  In
     this case the select call will report that stderr is closed
     immediately.  */
  if(cp->PipeNativeSTDERR[1] >= 0)
    {
    if(!kwsysProcessSetupOutputPipeNative(&si.StdErr, cp->PipeNativeSTDERR))
      {
      kwsysProcessCleanup(cp, 1);
      kwsysProcessCleanupDescriptor(&si.StdErr);
      return;
      }
    }

  /* The timeout period starts now.  */
  cp->StartTime = kwsysProcessTimeGetCurrent();
  cp->TimeoutTime.tv_sec = -1;
  cp->TimeoutTime.tv_usec = -1;

  /* Create the pipeline of processes.  */
  {
  int readEnd = -1;
  int failed = 0;
  for(i=0; i < cp->NumberOfCommands; ++i)
    {
    if(!kwsysProcessCreate(cp, i, &si, &readEnd))
      {
      failed = 1;
      }

    /* Set the output pipe of the last process to be non-blocking in
       case select lies, or for the polling implementation.  */
    if(i == (cp->NumberOfCommands-1) && !kwsysProcessSetNonBlocking(readEnd))
      {
      failed = 1;
      }

    if(failed)
      {
      kwsysProcessCleanup(cp, 1);

      /* Release resources that may have been allocated for this
         process before an error occurred.  */
      kwsysProcessCleanupDescriptor(&readEnd);
      if(si.StdIn != 0)
        {
        kwsysProcessCleanupDescriptor(&si.StdIn);
        }
      if(si.StdOut != 1)
        {
        kwsysProcessCleanupDescriptor(&si.StdOut);
        }
      if(si.StdErr != 2)
        {
        kwsysProcessCleanupDescriptor(&si.StdErr);
        }
      kwsysProcessCleanupDescriptor(&si.ErrorPipe[0]);
      kwsysProcessCleanupDescriptor(&si.ErrorPipe[1]);
      return;
      }
    }
  /* Save a handle to the output pipe for the last process.  */
  cp->PipeReadEnds[KWSYSPE_PIPE_STDOUT] = readEnd;
  }

  /* The parent process does not need the output pipe write ends.  */
  if(si.StdErr != 2)
    {
    kwsysProcessCleanupDescriptor(&si.StdErr);
    }

  /* Restore the working directory. */
  if(cp->RealWorkingDirectory)
    {
    /* Some platforms specify that the chdir call may be
       interrupted.  Repeat the call until it finishes.  */
    while((chdir(cp->RealWorkingDirectory) < 0) && (errno == EINTR));
    free(cp->RealWorkingDirectory);
    cp->RealWorkingDirectory = 0;
    }

  /* All the pipes are now open.  */
  cp->PipesLeft = KWSYSPE_PIPE_COUNT;

  /* The process has now started.  */
  cp->State = kwsysProcess_State_Executing;
  cp->Detached = cp->OptionDetach;
}

/*--------------------------------------------------------------------------*/
kwsysEXPORT void kwsysProcess_Disown(kwsysProcess* cp)
{
  /* Make sure a detached child process is running.  */
  if(!cp || !cp->Detached || cp->State != kwsysProcess_State_Executing ||
     cp->TimeoutExpired || cp->Killed)
    {
    return;
    }

  /* Close all the pipes safely.  */
  kwsysProcessClosePipes(cp);

  /* We will not wait for exit, so cleanup now.  */
  kwsysProcessCleanup(cp, 0);

  /* The process has been disowned.  */
  cp->State = kwsysProcess_State_Disowned;
}

/*--------------------------------------------------------------------------*/
typedef struct kwsysProcessWaitData_s
{
  int Expired;
  int PipeId;
  int User;
  double* UserTimeout;
  kwsysProcessTime TimeoutTime;
} kwsysProcessWaitData;
static int kwsysProcessWaitForPipe(kwsysProcess* cp, char** data, int* length,
                                   kwsysProcessWaitData* wd);

/*--------------------------------------------------------------------------*/
int kwsysProcess_WaitForData(kwsysProcess* cp, char** data, int* length,
                             double* userTimeout)
{
  kwsysProcessTime userStartTime = {0, 0};
  kwsysProcessWaitData wd =
    {
      0,
      kwsysProcess_Pipe_None,
      0,
      0,
      {0, 0}
    };
  wd.UserTimeout = userTimeout;
  /* Make sure we are executing a process.  */
  if(!cp || cp->State != kwsysProcess_State_Executing || cp->Killed ||
     cp->TimeoutExpired)
    {
    return kwsysProcess_Pipe_None;
    }

  /* Record the time at which user timeout period starts.  */
  if(userTimeout)
    {
    userStartTime = kwsysProcessTimeGetCurrent();
    }

  /* Calculate the time at which a timeout will expire, and whether it
     is the user or process timeout.  */
  wd.User = kwsysProcessGetTimeoutTime(cp, userTimeout,
                                       &wd.TimeoutTime);

  /* Data can only be available when pipes are open.  If the process
     is not running, cp->PipesLeft will be 0.  */
  while(cp->PipesLeft > 0 &&
        !kwsysProcessWaitForPipe(cp, data, length, &wd)) {}

  /* Update the user timeout.  */
  if(userTimeout)
    {
    kwsysProcessTime userEndTime = kwsysProcessTimeGetCurrent();
    kwsysProcessTime difference = kwsysProcessTimeSubtract(userEndTime,
                                                           userStartTime);
    double d = kwsysProcessTimeToDouble(difference);
    *userTimeout -= d;
    if(*userTimeout < 0)
      {
      *userTimeout = 0;
      }
    }

  /* Check what happened.  */