nspr-4.8.6/mozilla/nsprpub/pr/src/md/unix/uxproces.c - nest-learning-thermostat/5.1.5/nspr - Git at Google

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
  * The contents of this file are subject to the Mozilla Public License Version
  * 1.1 (the "License"); you may not use this file except in compliance with
  * the License. You may obtain a copy of the License at
  * http://www.mozilla.org/MPL/
  *
  * Software distributed under the License is distributed on an "AS IS" basis,
  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  * for the specific language governing rights and limitations under the
  * License.
  *
  * The Original Code is the Netscape Portable Runtime (NSPR).
  *
  * The Initial Developer of the Original Code is
  * Netscape Communications Corporation.
  * Portions created by the Initial Developer are Copyright (C) 1998-2000
  * the Initial Developer. All Rights Reserved.
  *
  * Contributor(s):
  *
  * Alternatively, the contents of this file may be used under the terms of
  * either the GNU General Public License Version 2 or later (the "GPL"), or
  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  * in which case the provisions of the GPL or the LGPL are applicable instead
  * of those above. If you wish to allow use of your version of this file only
  * under the terms of either the GPL or the LGPL, and not to allow others to
  * use your version of this file under the terms of the MPL, indicate your
  * decision by deleting the provisions above and replace them with the notice
  * and other provisions required by the GPL or the LGPL. If you do not delete
  * the provisions above, a recipient may use your version of this file under
  * the terms of any one of the MPL, the GPL or the LGPL.
  *
  * ***** END LICENSE BLOCK ***** */

 #include "primpl.h"

 #include <sys/types.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <sys/wait.h>
 #include <string.h>
 #if defined(AIX)
 #include <dlfcn.h>  /* For dlopen, dlsym, dlclose */
 #endif

 #if defined(DARWIN)
 #include <crt_externs.h>
 #else
 PR_IMPORT_DATA(char **) environ;
 #endif

 /*
  * HP-UX 9 doesn't have the SA_RESTART flag.
  */
 #ifndef SA_RESTART
 #define SA_RESTART 0
 #endif

 /*
  **********************************************************************
  *
  * The Unix process routines
  *
  **********************************************************************
  */

 #define _PR_SIGNALED_EXITSTATUS 256

 typedef enum pr_PidState {
     _PR_PID_DETACHED,
     _PR_PID_REAPED,
     _PR_PID_WAITING
 } pr_PidState;

 typedef struct pr_PidRecord {
     pid_t pid;
     int exitStatus;
     pr_PidState state;
     PRCondVar *reapedCV;
     struct pr_PidRecord *next;
 } pr_PidRecord;

 /*
  * Irix sprocs and LinuxThreads are actually a kind of processes
  * that can share the virtual address space and file descriptors.
  */
 #if (defined(IRIX) && !defined(_PR_PTHREADS)) \
         || ((defined(LINUX) || defined(__GNU__) || defined(__GLIBC__)) \
         && defined(_PR_PTHREADS))
 #define _PR_SHARE_CLONES
 #endif

 /*
  * The macro _PR_NATIVE_THREADS indicates that we are
  * using native threads only, so waitpid() blocks just the
  * calling thread, not the process.  In this case, the waitpid
  * daemon thread can safely block in waitpid().  So we don't
  * need to catch SIGCHLD, and the pipe to unblock PR_Poll() is
  * also not necessary.
  */

 #if defined(_PR_GLOBAL_THREADS_ONLY) \
 	|| (defined(_PR_PTHREADS) \
 	&& !defined(LINUX) && !defined(__GNU__) && !defined(__GLIBC__))
 #define _PR_NATIVE_THREADS
 #endif

 /*
  * All the static variables used by the Unix process routines are
  * collected in this structure.
  */

 static struct {
     PRCallOnceType once;
     PRThread *thread;
     PRLock *ml;
 #if defined(_PR_NATIVE_THREADS)
     PRInt32 numProcs;
     PRCondVar *cv;
 #else
     int pipefd[2];
 #endif
     pr_PidRecord **pidTable;

 #ifdef _PR_SHARE_CLONES
     struct pr_CreateProcOp *opHead, *opTail;
 #endif

 #ifdef AIX
     pid_t (*forkptr)(void);  /* Newer versions of AIX (starting in 4.3.2)
                               * have f_fork, which is faster than the
                               * regular fork in a multithreaded process
                               * because it skips calling the fork handlers.
                               * So we look up the f_fork symbol to see if
                               * it's available and fall back on fork.
                               */
 #endif /* AIX */
 } pr_wp;

 #ifdef _PR_SHARE_CLONES
 static int pr_waitpid_daemon_exit;

 void
 _MD_unix_terminate_waitpid_daemon(void)
 {
     if (pr_wp.thread) {
         pr_waitpid_daemon_exit = 1;
         write(pr_wp.pipefd[1], "", 1);
         PR_JoinThread(pr_wp.thread);
     }
 }
 #endif

 static PRStatus _MD_InitProcesses(void);
 #if !defined(_PR_NATIVE_THREADS)
 static void pr_InstallSigchldHandler(void);
 #endif

 static PRProcess *
 ForkAndExec(
     const char *path,
     char *const *argv,
     char *const *envp,
     const PRProcessAttr *attr)
 {
     PRProcess *process;
     int nEnv, idx;
     char *const *childEnvp;
     char **newEnvp = NULL;
     int flags;

     process = PR_NEW(PRProcess);
     if (!process) {
         PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
         return NULL;
     }

     childEnvp = envp;
     if (attr && attr->fdInheritBuffer) {
         PRBool found = PR_FALSE;

         if (NULL == childEnvp) {
 #ifdef DARWIN
             childEnvp = *(_NSGetEnviron());
 #else
             childEnvp = environ;
 #endif
         }
         for (nEnv = 0; childEnvp[nEnv]; nEnv++) {
         }
         newEnvp = (char **) PR_MALLOC((nEnv + 2) * sizeof(char *));
         if (NULL == newEnvp) {
             PR_DELETE(process);
             PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
             return NULL;
         }
         for (idx = 0; idx < nEnv; idx++) {
             newEnvp[idx] = childEnvp[idx];
             if (!found && !strncmp(newEnvp[idx], "NSPR_INHERIT_FDS=", 17)) {
                 newEnvp[idx] = attr->fdInheritBuffer;
                 found = PR_TRUE;
             }
         }
         if (!found) {
             newEnvp[idx++] = attr->fdInheritBuffer;
         }
         newEnvp[idx] = NULL;
         childEnvp = newEnvp;
     }

 #ifdef AIX
     process->md.pid = (*pr_wp.forkptr)();
 #elif defined(NTO) || defined(SYMBIAN)
     /*
      * fork() & exec() does not work in a multithreaded process.
      * Use spawn() instead.
      */
     {
         int fd_map[3] = { 0, 1, 2 };

         if (attr) {
             if (attr->stdinFd && attr->stdinFd->secret->md.osfd != 0) {
                 fd_map[0] = dup(attr->stdinFd->secret->md.osfd);
                 flags = fcntl(fd_map[0], F_GETFL, 0);
                 if (flags & O_NONBLOCK)
                     fcntl(fd_map[0], F_SETFL, flags & ~O_NONBLOCK);
             }
             if (attr->stdoutFd && attr->stdoutFd->secret->md.osfd != 1) {
                 fd_map[1] = dup(attr->stdoutFd->secret->md.osfd);
                 flags = fcntl(fd_map[1], F_GETFL, 0);
                 if (flags & O_NONBLOCK)
                     fcntl(fd_map[1], F_SETFL, flags & ~O_NONBLOCK);
             }
             if (attr->stderrFd && attr->stderrFd->secret->md.osfd != 2) {
                 fd_map[2] = dup(attr->stderrFd->secret->md.osfd);
                 flags = fcntl(fd_map[2], F_GETFL, 0);
                 if (flags & O_NONBLOCK)
                     fcntl(fd_map[2], F_SETFL, flags & ~O_NONBLOCK);
             }

             PR_ASSERT(attr->currentDirectory == NULL);  /* not implemented */
         }

 #ifdef SYMBIAN
         /* In Symbian OS, we use posix_spawn instead of fork() and exec() */
         posix_spawn(&(process->md.pid), path, NULL, NULL, argv, childEnvp);
 #else
         process->md.pid = spawn(path, 3, fd_map, NULL, argv, childEnvp);
 #endif

         if (fd_map[0] != 0)
             close(fd_map[0]);
         if (fd_map[1] != 1)
             close(fd_map[1]);
         if (fd_map[2] != 2)
             close(fd_map[2]);
     }
 #else
     process->md.pid = fork();
 #endif
     if ((pid_t) -1 == process->md.pid) {
         PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, errno);
         PR_DELETE(process);
         if (newEnvp) {
             PR_DELETE(newEnvp);
         }
         return NULL;
     } else if (0 == process->md.pid) {  /* the child process */
         /*
          * If the child process needs to exit, it must call _exit().
          * Do not call exit(), because exit() will flush and close
          * the standard I/O file descriptors, and hence corrupt
          * the parent process's standard I/O data structures.
          */

 #if !defined(NTO) && !defined(SYMBIAN)
         if (attr) {
             /* the osfd's to redirect stdin, stdout, and stderr to */
             int in_osfd = -1, out_osfd = -1, err_osfd = -1;

             if (attr->stdinFd
                     && attr->stdinFd->secret->md.osfd != 0) {
                 in_osfd = attr->stdinFd->secret->md.osfd;
                 if (dup2(in_osfd, 0) != 0) {
                     _exit(1);  /* failed */
                 }
                 flags = fcntl(0, F_GETFL, 0);
                 if (flags & O_NONBLOCK) {
                     fcntl(0, F_SETFL, flags & ~O_NONBLOCK);
                 }
             }
             if (attr->stdoutFd
                     && attr->stdoutFd->secret->md.osfd != 1) {
                 out_osfd = attr->stdoutFd->secret->md.osfd;
                 if (dup2(out_osfd, 1) != 1) {
                     _exit(1);  /* failed */
                 }
                 flags = fcntl(1, F_GETFL, 0);
                 if (flags & O_NONBLOCK) {
                     fcntl(1, F_SETFL, flags & ~O_NONBLOCK);
                 }
             }
             if (attr->stderrFd
                     && attr->stderrFd->secret->md.osfd != 2) {
                 err_osfd = attr->stderrFd->secret->md.osfd;
                 if (dup2(err_osfd, 2) != 2) {
                     _exit(1);  /* failed */
                 }
                 flags = fcntl(2, F_GETFL, 0);
                 if (flags & O_NONBLOCK) {
                     fcntl(2, F_SETFL, flags & ~O_NONBLOCK);
                 }
             }
             if (in_osfd != -1) {
                 close(in_osfd);
             }
             if (out_osfd != -1 && out_osfd != in_osfd) {
                 close(out_osfd);
             }
             if (err_osfd != -1 && err_osfd != in_osfd
                     && err_osfd != out_osfd) {
                 close(err_osfd);
             }
             if (attr->currentDirectory) {
                 if (chdir(attr->currentDirectory) < 0) {
                     _exit(1);  /* failed */
                 }
             }
         }

         if (childEnvp) {
             (void)execve(path, argv, childEnvp);
         } else {
             /* Inherit the environment of the parent. */
             (void)execv(path, argv);
         }
         /* Whoops! It returned. That's a bad sign. */
         _exit(1);
 #endif /* !NTO */
     }

     if (newEnvp) {
         PR_DELETE(newEnvp);
     }

 #if defined(_PR_NATIVE_THREADS)
     PR_Lock(pr_wp.ml);
     if (0 == pr_wp.numProcs++) {
         PR_NotifyCondVar(pr_wp.cv);
     }
     PR_Unlock(pr_wp.ml);
 #endif
     return process;
 }

 #ifdef _PR_SHARE_CLONES

 struct pr_CreateProcOp {
     const char *path;
     char *const *argv;
     char *const *envp;
     const PRProcessAttr *attr;
     PRProcess *process;
     PRErrorCode prerror;
     PRInt32 oserror;
     PRBool done;
     PRCondVar *doneCV;
     struct pr_CreateProcOp *next;
 };

 PRProcess *
 _MD_CreateUnixProcess(
     const char *path,
     char *const *argv,
     char *const *envp,
     const PRProcessAttr *attr)
 {
     struct pr_CreateProcOp *op;
     PRProcess *proc;
     int rv;

     if (PR_CallOnce(&pr_wp.once, _MD_InitProcesses) == PR_FAILURE) {
 	return NULL;
     }

     op = PR_NEW(struct pr_CreateProcOp);
     if (NULL == op) {
 	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
 	return NULL;
     }
     op->path = path;
     op->argv = argv;
     op->envp = envp;
     op->attr = attr;
     op->done = PR_FALSE;
     op->doneCV = PR_NewCondVar(pr_wp.ml);
     if (NULL == op->doneCV) {
 	PR_DELETE(op);
 	return NULL;
     }
     PR_Lock(pr_wp.ml);

     /* add to the tail of op queue */
     op->next = NULL;
     if (pr_wp.opTail) {
 	pr_wp.opTail->next = op;
 	pr_wp.opTail = op;
     } else {
 	PR_ASSERT(NULL == pr_wp.opHead);
 	pr_wp.opHead = pr_wp.opTail = op;
     }

     /* wake up the daemon thread */
     do {
         rv = write(pr_wp.pipefd[1], "", 1);
     } while (-1 == rv && EINTR == errno);

     while (op->done == PR_FALSE) {
 	PR_WaitCondVar(op->doneCV, PR_INTERVAL_NO_TIMEOUT);
     }
     PR_Unlock(pr_wp.ml);
     PR_DestroyCondVar(op->doneCV);
     proc = op->process;
     if (!proc) {
 	PR_SetError(op->prerror, op->oserror);
     }
     PR_DELETE(op);
     return proc;
 }

 #else  /* ! _PR_SHARE_CLONES */

 PRProcess *
 _MD_CreateUnixProcess(
     const char *path,
     char *const *argv,
     char *const *envp,
     const PRProcessAttr *attr)
 {
     if (PR_CallOnce(&pr_wp.once, _MD_InitProcesses) == PR_FAILURE) {
 	return NULL;
     }
     return ForkAndExec(path, argv, envp, attr);
 }  /* _MD_CreateUnixProcess */

 #endif  /* _PR_SHARE_CLONES */

 /*
  * The pid table is a hashtable.
  *
  * The number of buckets in the hashtable (NBUCKETS) must be a power of 2.
  */
 #define NBUCKETS_LOG2 6
 #define NBUCKETS (1 << NBUCKETS_LOG2)
 #define PID_HASH_MASK ((pid_t) (NBUCKETS - 1))

 static pr_PidRecord *
 FindPidTable(pid_t pid)
 {
     pr_PidRecord *pRec;
     int keyHash = (int) (pid & PID_HASH_MASK);

     pRec =  pr_wp.pidTable[keyHash];
     while (pRec) {
 	if (pRec->pid == pid) {
 	    break;
 	}
 	pRec = pRec->next;
     }
     return pRec;
 }

 static void
 InsertPidTable(pr_PidRecord *pRec)
 {
     int keyHash = (int) (pRec->pid & PID_HASH_MASK);

     pRec->next = pr_wp.pidTable[keyHash];
     pr_wp.pidTable[keyHash] = pRec;
 }

 static void
 DeletePidTable(pr_PidRecord *pRec)
 {
     int keyHash = (int) (pRec->pid & PID_HASH_MASK);

     if (pr_wp.pidTable[keyHash] == pRec) {
 	pr_wp.pidTable[keyHash] = pRec->next;
     } else {
 	pr_PidRecord *pred, *cur;  /* predecessor and current */

 	pred = pr_wp.pidTable[keyHash];
 	cur = pred->next;
 	while (cur) {
 	    if (cur == pRec) {
 		pred->next = cur->next;
 		break;
             }
 	    pred = cur;
 	    cur = cur->next;
         }
 	PR_ASSERT(cur != NULL);
     }
 }

 static int
 ExtractExitStatus(int rawExitStatus)
 {
     /*
      * We did not specify the WCONTINUED and WUNTRACED options
      * for waitpid, so these two events should not be reported.
      */
     PR_ASSERT(!WIFSTOPPED(rawExitStatus));
 #ifdef WIFCONTINUED
     PR_ASSERT(!WIFCONTINUED(rawExitStatus));
 #endif
     if (WIFEXITED(rawExitStatus)) {
 	return WEXITSTATUS(rawExitStatus);
     } else {
 	PR_ASSERT(WIFSIGNALED(rawExitStatus));
 	return _PR_SIGNALED_EXITSTATUS;
     }
 }

 static void
 ProcessReapedChildInternal(pid_t pid, int status)
 {
     pr_PidRecord *pRec;

     pRec = FindPidTable(pid);
     if (NULL == pRec) {
         pRec = PR_NEW(pr_PidRecord);
         pRec->pid = pid;
         pRec->state = _PR_PID_REAPED;
         pRec->exitStatus = ExtractExitStatus(status);
         pRec->reapedCV = NULL;
         InsertPidTable(pRec);
     } else {
         PR_ASSERT(pRec->state != _PR_PID_REAPED);
         if (_PR_PID_DETACHED == pRec->state) {
             PR_ASSERT(NULL == pRec->reapedCV);
             DeletePidTable(pRec);
             PR_DELETE(pRec);
         } else {
             PR_ASSERT(_PR_PID_WAITING == pRec->state);
             PR_ASSERT(NULL != pRec->reapedCV);
             pRec->exitStatus = ExtractExitStatus(status);
             pRec->state = _PR_PID_REAPED;
             PR_NotifyCondVar(pRec->reapedCV);
         }
     }
 }

 #if defined(_PR_NATIVE_THREADS)

 /*
  * If all the threads are native threads, the daemon thread is
  * simpler.  We don't need to catch the SIGCHLD signal.  We can
  * just have the daemon thread block in waitpid().
  */

 static void WaitPidDaemonThread(void *unused)
 {
     pid_t pid;
     int status;

     while (1) {
         PR_Lock(pr_wp.ml);
         while (0 == pr_wp.numProcs) {
             PR_WaitCondVar(pr_wp.cv, PR_INTERVAL_NO_TIMEOUT);
         }
         PR_Unlock(pr_wp.ml);

 	while (1) {
 	    do {
 	        pid = waitpid((pid_t) -1, &status, 0);
 	    } while ((pid_t) -1 == pid && EINTR == errno);

             /*
              * waitpid() cannot return 0 because we did not invoke it
              * with the WNOHANG option.
              */
 	    PR_ASSERT(0 != pid);

             /*
              * The only possible error code is ECHILD.  But if we do
              * our accounting correctly, we should only call waitpid()
              * when there is a child process to wait for.
              */
             PR_ASSERT((pid_t) -1 != pid);
 	    if ((pid_t) -1 == pid) {
                 break;
             }

 	    PR_Lock(pr_wp.ml);
             ProcessReapedChildInternal(pid, status);
             pr_wp.numProcs--;
             while (0 == pr_wp.numProcs) {
                 PR_WaitCondVar(pr_wp.cv, PR_INTERVAL_NO_TIMEOUT);
             }
 	    PR_Unlock(pr_wp.ml);
 	}
     }
 }

 #else /* _PR_NATIVE_THREADS */

 static void WaitPidDaemonThread(void *unused)
 {
     PRPollDesc pd;
     PRFileDesc *fd;
     int rv;
     char buf[128];
     pid_t pid;
     int status;
 #ifdef _PR_SHARE_CLONES
     struct pr_CreateProcOp *op;
 #endif

 #ifdef _PR_SHARE_CLONES
     pr_InstallSigchldHandler();
 #endif

     fd = PR_ImportFile(pr_wp.pipefd[0]);
     PR_ASSERT(NULL != fd);
     pd.fd = fd;
     pd.in_flags = PR_POLL_READ;

     while (1) {
         rv = PR_Poll(&pd, 1, PR_INTERVAL_NO_TIMEOUT);
         PR_ASSERT(1 == rv);

 #ifdef _PR_SHARE_CLONES
         if (pr_waitpid_daemon_exit) {
             return;
         }
 	PR_Lock(pr_wp.ml);
 #endif

         do {
             rv = read(pr_wp.pipefd[0], buf, sizeof(buf));
         } while (sizeof(buf) == rv || (-1 == rv && EINTR == errno));

 #ifdef _PR_SHARE_CLONES
 	PR_Unlock(pr_wp.ml);
 	while ((op = pr_wp.opHead) != NULL) {
 	    op->process = ForkAndExec(op->path, op->argv,
 		    op->envp, op->attr);
 	    if (NULL == op->process) {
 		op->prerror = PR_GetError();
 		op->oserror = PR_GetOSError();
 	    }
 	    PR_Lock(pr_wp.ml);
 	    pr_wp.opHead = op->next;
 	    if (NULL == pr_wp.opHead) {
 		pr_wp.opTail = NULL;
 	    }
 	    op->done = PR_TRUE;
 	    PR_NotifyCondVar(op->doneCV);
 	    PR_Unlock(pr_wp.ml);
 	}
 #endif

 	while (1) {
 	    do {
 	        pid = waitpid((pid_t) -1, &status, WNOHANG);
 	    } while ((pid_t) -1 == pid && EINTR == errno);
 	    if (0 == pid) break;
 	    if ((pid_t) -1 == pid) {
 		/* must be because we have no child processes */
 		PR_ASSERT(ECHILD == errno);
 		break;
             }

 	    PR_Lock(pr_wp.ml);
             ProcessReapedChildInternal(pid, status);
 	    PR_Unlock(pr_wp.ml);
 	}
     }
 }

 static void pr_SigchldHandler(int sig)
 {
     int errnoCopy;
     int rv;

     errnoCopy = errno;

     do {
         rv = write(pr_wp.pipefd[1], "", 1);
     } while (-1 == rv && EINTR == errno);

 #ifdef DEBUG
     if (-1 == rv && EAGAIN != errno && EWOULDBLOCK != errno) {
         char *msg = "cannot write to pipe\n";
         write(2, msg, strlen(msg) + 1);
         _exit(1);
     }
 #endif

     errno = errnoCopy;
 }

 static void pr_InstallSigchldHandler()
 {
 #if defined(HPUX) && defined(_PR_DCETHREADS)
 #error "HP-UX DCE threads have their own SIGCHLD handler"
 #endif

     struct sigaction act, oact;
     int rv;

     act.sa_handler = pr_SigchldHandler;
     sigemptyset(&act.sa_mask);
     act.sa_flags = SA_NOCLDSTOP | SA_RESTART;
     rv = sigaction(SIGCHLD, &act, &oact);
     PR_ASSERT(0 == rv);
     /* Make sure we are not overriding someone else's SIGCHLD handler */
 #ifndef _PR_SHARE_CLONES
     PR_ASSERT(oact.sa_handler == SIG_DFL);
 #endif
 }

 #endif  /* !defined(_PR_NATIVE_THREADS) */

 static PRStatus _MD_InitProcesses(void)
 {
 #if !defined(_PR_NATIVE_THREADS)
     int rv;
     int flags;
 #endif
 #ifdef SUNOS4
 #define _PR_NBIO_FLAG FNDELAY
 #else
 #define _PR_NBIO_FLAG O_NONBLOCK
 #endif

 #ifdef AIX
     {
         void *handle = dlopen(NULL, RTLD_NOW | RTLD_GLOBAL);
         pr_wp.forkptr = (pid_t (*)(void)) dlsym(handle, "f_fork");
         if (!pr_wp.forkptr) {
             pr_wp.forkptr = fork;
         }
         dlclose(handle);
     }
 #endif /* AIX */

     pr_wp.ml = PR_NewLock();
     PR_ASSERT(NULL != pr_wp.ml);

 #if defined(_PR_NATIVE_THREADS)
     pr_wp.numProcs = 0;
     pr_wp.cv = PR_NewCondVar(pr_wp.ml);
     PR_ASSERT(NULL != pr_wp.cv);
 #else
     rv = pipe(pr_wp.pipefd);
     PR_ASSERT(0 == rv);
     flags = fcntl(pr_wp.pipefd[0], F_GETFL, 0);
     fcntl(pr_wp.pipefd[0], F_SETFL, flags | _PR_NBIO_FLAG);
     flags = fcntl(pr_wp.pipefd[1], F_GETFL, 0);
     fcntl(pr_wp.pipefd[1], F_SETFL, flags | _PR_NBIO_FLAG);

 #ifndef _PR_SHARE_CLONES
     pr_InstallSigchldHandler();
 #endif
 #endif  /* !_PR_NATIVE_THREADS */

     pr_wp.thread = PR_CreateThread(PR_SYSTEM_THREAD,
 	    WaitPidDaemonThread, NULL, PR_PRIORITY_NORMAL,
 #ifdef _PR_SHARE_CLONES
             PR_GLOBAL_THREAD,
 #else
 	    PR_LOCAL_THREAD,
 #endif
 	    PR_JOINABLE_THREAD, 0);
     PR_ASSERT(NULL != pr_wp.thread);

     pr_wp.pidTable = (pr_PidRecord**)PR_CALLOC(NBUCKETS * sizeof(pr_PidRecord *));
     PR_ASSERT(NULL != pr_wp.pidTable);
     return PR_SUCCESS;
 }

 PRStatus _MD_DetachUnixProcess(PRProcess *process)
 {
     PRStatus retVal = PR_SUCCESS;
     pr_PidRecord *pRec;

     PR_Lock(pr_wp.ml);
     pRec = FindPidTable(process->md.pid);
     if (NULL == pRec) {
 	pRec = PR_NEW(pr_PidRecord);
 	if (NULL == pRec) {
 	    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
 	    retVal = PR_FAILURE;
 	    goto done;
 	}
 	pRec->pid = process->md.pid;
 	pRec->state = _PR_PID_DETACHED;
 	pRec->reapedCV = NULL;
 	InsertPidTable(pRec);
     } else {
 	PR_ASSERT(_PR_PID_REAPED == pRec->state);
 	if (_PR_PID_REAPED != pRec->state) {
 	    PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
 	    retVal = PR_FAILURE;
 	} else {
 	    DeletePidTable(pRec);
 	    PR_ASSERT(NULL == pRec->reapedCV);
 	    PR_DELETE(pRec);
 	}
     }
     PR_DELETE(process);

 done:
     PR_Unlock(pr_wp.ml);
     return retVal;
 }

 PRStatus _MD_WaitUnixProcess(
     PRProcess *process,
     PRInt32 *exitCode)
 {
     pr_PidRecord *pRec;
     PRStatus retVal = PR_SUCCESS;
     PRBool interrupted = PR_FALSE;

     PR_Lock(pr_wp.ml);
     pRec = FindPidTable(process->md.pid);
     if (NULL == pRec) {
 	pRec = PR_NEW(pr_PidRecord);
 	if (NULL == pRec) {
 	    PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
 	    retVal = PR_FAILURE;
 	    goto done;
 	}
 	pRec->pid = process->md.pid;
 	pRec->state = _PR_PID_WAITING;
 	pRec->reapedCV = PR_NewCondVar(pr_wp.ml);
 	if (NULL == pRec->reapedCV) {
 	    PR_DELETE(pRec);
 	    retVal = PR_FAILURE;
 	    goto done;
 	}
 	InsertPidTable(pRec);
 	while (!interrupted && _PR_PID_REAPED != pRec->state) {
 	    if (PR_WaitCondVar(pRec->reapedCV,
 		    PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE
 		    && PR_GetError() == PR_PENDING_INTERRUPT_ERROR) {
 		interrupted = PR_TRUE;
             }
 	}
 	if (_PR_PID_REAPED == pRec->state) {
             if (exitCode) {
                 *exitCode = pRec->exitStatus;
             }
 	} else {
 	    PR_ASSERT(interrupted);
 	    retVal = PR_FAILURE;
 	}
 	DeletePidTable(pRec);
 	PR_DestroyCondVar(pRec->reapedCV);
 	PR_DELETE(pRec);
     } else {
 	PR_ASSERT(_PR_PID_REAPED == pRec->state);
 	PR_ASSERT(NULL == pRec->reapedCV);
 	DeletePidTable(pRec);
         if (exitCode) {
             *exitCode = pRec->exitStatus;
         }
 	PR_DELETE(pRec);
     }
     PR_DELETE(process);

 done:
     PR_Unlock(pr_wp.ml);
     return retVal;
 }  /* _MD_WaitUnixProcess */

 PRStatus _MD_KillUnixProcess(PRProcess *process)
 {
     PRErrorCode prerror;
     PRInt32 oserror;

 #ifdef SYMBIAN
     /* In Symbian OS, we can not kill other process with Open C */
     PR_SetError(PR_OPERATION_NOT_SUPPORTED_ERROR, oserror);
     return PR_FAILURE;
 #else
     if (kill(process->md.pid, SIGKILL) == 0) {
 	return PR_SUCCESS;
     }
     oserror = errno;
     switch (oserror) {
         case EPERM:
 	    prerror = PR_NO_ACCESS_RIGHTS_ERROR;
 	    break;
         case ESRCH:
 	    prerror = PR_INVALID_ARGUMENT_ERROR;
 	    break;
         default:
 	    prerror = PR_UNKNOWN_ERROR;
 	    break;
     }
     PR_SetError(prerror, oserror);
     return PR_FAILURE;
 #endif
 }  /* _MD_KillUnixProcess */
	/* -- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -- */
	/* *** BEGIN LICENSE BLOCK ***
	* Version: MPL 1.1/GPL 2.0/LGPL 2.1
	*
	* The contents of this file are subject to the Mozilla Public License Version
	* 1.1 (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	* http://www.mozilla.org/MPL/
	*
	* Software distributed under the License is distributed on an "AS IS" basis,
	* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
	* for the specific language governing rights and limitations under the
	* License.
	*
	* The Original Code is the Netscape Portable Runtime (NSPR).
	*
	* The Initial Developer of the Original Code is
	* Netscape Communications Corporation.
	* Portions created by the Initial Developer are Copyright (C) 1998-2000
	* the Initial Developer. All Rights Reserved.
	*
	* Contributor(s):
	*
	* Alternatively, the contents of this file may be used under the terms of
	* either the GNU General Public License Version 2 or later (the "GPL"), or
	* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
	* in which case the provisions of the GPL or the LGPL are applicable instead
	* of those above. If you wish to allow use of your version of this file only
	* under the terms of either the GPL or the LGPL, and not to allow others to
	* use your version of this file under the terms of the MPL, indicate your
	* decision by deleting the provisions above and replace them with the notice
	* and other provisions required by the GPL or the LGPL. If you do not delete
	* the provisions above, a recipient may use your version of this file under
	* the terms of any one of the MPL, the GPL or the LGPL.
	*
	* *** END LICENSE BLOCK *** */

	#include "primpl.h"

	#include <sys/types.h>
	#include <unistd.h>
	#include <fcntl.h>
	#include <signal.h>
	#include <sys/wait.h>
	#include <string.h>
	#if defined(AIX)
	#include <dlfcn.h> /* For dlopen, dlsym, dlclose */
	#endif

	#if defined(DARWIN)
	#include <crt_externs.h>
	#else
	PR_IMPORT_DATA(char **) environ;
	#endif

	/*
	* HP-UX 9 doesn't have the SA_RESTART flag.
	*/
	#ifndef SA_RESTART
	#define SA_RESTART 0
	#endif

	/*
	**********************************************************************
	*
	* The Unix process routines
	*
	**********************************************************************
	*/

	#define _PR_SIGNALED_EXITSTATUS 256

	typedef enum pr_PidState {
	_PR_PID_DETACHED,
	_PR_PID_REAPED,
	_PR_PID_WAITING
	} pr_PidState;

	typedef struct pr_PidRecord {
	pid_t pid;
	int exitStatus;
	pr_PidState state;
	PRCondVar *reapedCV;
	struct pr_PidRecord *next;
	} pr_PidRecord;

	/*
	* Irix sprocs and LinuxThreads are actually a kind of processes
	* that can share the virtual address space and file descriptors.
	*/
	#if (defined(IRIX) && !defined(_PR_PTHREADS)) \
	\|\| ((defined(LINUX) \|\| defined(__GNU__) \|\| defined(__GLIBC__)) \
	&& defined(_PR_PTHREADS))
	#define _PR_SHARE_CLONES
	#endif

	/*
	* The macro _PR_NATIVE_THREADS indicates that we are
	* using native threads only, so waitpid() blocks just the
	* calling thread, not the process. In this case, the waitpid
	* daemon thread can safely block in waitpid(). So we don't
	* need to catch SIGCHLD, and the pipe to unblock PR_Poll() is
	* also not necessary.
	*/

	#if defined(_PR_GLOBAL_THREADS_ONLY) \
	\|\| (defined(_PR_PTHREADS) \
	&& !defined(LINUX) && !defined(__GNU__) && !defined(__GLIBC__))
	#define _PR_NATIVE_THREADS
	#endif

	/*
	* All the static variables used by the Unix process routines are
	* collected in this structure.
	*/

	static struct {
	PRCallOnceType once;
	PRThread *thread;
	PRLock *ml;
	#if defined(_PR_NATIVE_THREADS)
	PRInt32 numProcs;
	PRCondVar *cv;
	#else
	int pipefd[2];
	#endif
	pr_PidRecord **pidTable;

	#ifdef _PR_SHARE_CLONES
	struct pr_CreateProcOp opHead, opTail;
	#endif

	#ifdef AIX
	pid_t (forkptr)(void); / Newer versions of AIX (starting in 4.3.2)
	* have f_fork, which is faster than the
	* regular fork in a multithreaded process
	* because it skips calling the fork handlers.
	* So we look up the f_fork symbol to see if
	* it's available and fall back on fork.
	*/
	#endif /* AIX */
	} pr_wp;

	#ifdef _PR_SHARE_CLONES
	static int pr_waitpid_daemon_exit;

	void
	_MD_unix_terminate_waitpid_daemon(void)
	{
	if (pr_wp.thread) {
	pr_waitpid_daemon_exit = 1;
	write(pr_wp.pipefd[1], "", 1);
	PR_JoinThread(pr_wp.thread);
	}
	}
	#endif

	static PRStatus _MD_InitProcesses(void);
	#if !defined(_PR_NATIVE_THREADS)
	static void pr_InstallSigchldHandler(void);
	#endif

	static PRProcess *
	ForkAndExec(
	const char *path,
	char const argv,
	char const envp,
	const PRProcessAttr *attr)
	{
	PRProcess *process;
	int nEnv, idx;
	char const childEnvp;
	char **newEnvp = NULL;
	int flags;

	process = PR_NEW(PRProcess);
	if (!process) {
	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
	return NULL;
	}

	childEnvp = envp;
	if (attr && attr->fdInheritBuffer) {
	PRBool found = PR_FALSE;

	if (NULL == childEnvp) {
	#ifdef DARWIN
	childEnvp = *(_NSGetEnviron());
	#else
	childEnvp = environ;
	#endif
	}
	for (nEnv = 0; childEnvp[nEnv]; nEnv++) {
	}
	newEnvp = (char *) PR_MALLOC((nEnv + 2) sizeof(char *));
	if (NULL == newEnvp) {
	PR_DELETE(process);
	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
	return NULL;
	}
	for (idx = 0; idx < nEnv; idx++) {
	newEnvp[idx] = childEnvp[idx];
	if (!found && !strncmp(newEnvp[idx], "NSPR_INHERIT_FDS=", 17)) {
	newEnvp[idx] = attr->fdInheritBuffer;
	found = PR_TRUE;
	}
	}
	if (!found) {
	newEnvp[idx++] = attr->fdInheritBuffer;
	}
	newEnvp[idx] = NULL;
	childEnvp = newEnvp;
	}

	#ifdef AIX
	process->md.pid = (*pr_wp.forkptr)();
	#elif defined(NTO) \|\| defined(SYMBIAN)
	/*
	* fork() & exec() does not work in a multithreaded process.
	* Use spawn() instead.
	*/
	{
	int fd_map[3] = { 0, 1, 2 };

	if (attr) {
	if (attr->stdinFd && attr->stdinFd->secret->md.osfd != 0) {
	fd_map[0] = dup(attr->stdinFd->secret->md.osfd);
	flags = fcntl(fd_map[0], F_GETFL, 0);
	if (flags & O_NONBLOCK)
	fcntl(fd_map[0], F_SETFL, flags & ~O_NONBLOCK);
	}
	if (attr->stdoutFd && attr->stdoutFd->secret->md.osfd != 1) {
	fd_map[1] = dup(attr->stdoutFd->secret->md.osfd);
	flags = fcntl(fd_map[1], F_GETFL, 0);
	if (flags & O_NONBLOCK)
	fcntl(fd_map[1], F_SETFL, flags & ~O_NONBLOCK);
	}
	if (attr->stderrFd && attr->stderrFd->secret->md.osfd != 2) {
	fd_map[2] = dup(attr->stderrFd->secret->md.osfd);
	flags = fcntl(fd_map[2], F_GETFL, 0);
	if (flags & O_NONBLOCK)
	fcntl(fd_map[2], F_SETFL, flags & ~O_NONBLOCK);
	}

	PR_ASSERT(attr->currentDirectory == NULL); /* not implemented */
	}

	#ifdef SYMBIAN
	/* In Symbian OS, we use posix_spawn instead of fork() and exec() */
	posix_spawn(&(process->md.pid), path, NULL, NULL, argv, childEnvp);
	#else
	process->md.pid = spawn(path, 3, fd_map, NULL, argv, childEnvp);
	#endif

	if (fd_map[0] != 0)
	close(fd_map[0]);
	if (fd_map[1] != 1)
	close(fd_map[1]);
	if (fd_map[2] != 2)
	close(fd_map[2]);
	}
	#else
	process->md.pid = fork();
	#endif
	if ((pid_t) -1 == process->md.pid) {
	PR_SetError(PR_INSUFFICIENT_RESOURCES_ERROR, errno);
	PR_DELETE(process);
	if (newEnvp) {
	PR_DELETE(newEnvp);
	}
	return NULL;
	} else if (0 == process->md.pid) { /* the child process */
	/*
	* If the child process needs to exit, it must call _exit().
	* Do not call exit(), because exit() will flush and close
	* the standard I/O file descriptors, and hence corrupt
	* the parent process's standard I/O data structures.
	*/

	#if !defined(NTO) && !defined(SYMBIAN)
	if (attr) {
	/* the osfd's to redirect stdin, stdout, and stderr to */
	int in_osfd = -1, out_osfd = -1, err_osfd = -1;

	if (attr->stdinFd
	&& attr->stdinFd->secret->md.osfd != 0) {
	in_osfd = attr->stdinFd->secret->md.osfd;
	if (dup2(in_osfd, 0) != 0) {
	_exit(1); /* failed */
	}
	flags = fcntl(0, F_GETFL, 0);
	if (flags & O_NONBLOCK) {
	fcntl(0, F_SETFL, flags & ~O_NONBLOCK);
	}
	}
	if (attr->stdoutFd
	&& attr->stdoutFd->secret->md.osfd != 1) {
	out_osfd = attr->stdoutFd->secret->md.osfd;
	if (dup2(out_osfd, 1) != 1) {
	_exit(1); /* failed */
	}
	flags = fcntl(1, F_GETFL, 0);
	if (flags & O_NONBLOCK) {
	fcntl(1, F_SETFL, flags & ~O_NONBLOCK);
	}
	}
	if (attr->stderrFd
	&& attr->stderrFd->secret->md.osfd != 2) {
	err_osfd = attr->stderrFd->secret->md.osfd;
	if (dup2(err_osfd, 2) != 2) {
	_exit(1); /* failed */
	}
	flags = fcntl(2, F_GETFL, 0);
	if (flags & O_NONBLOCK) {
	fcntl(2, F_SETFL, flags & ~O_NONBLOCK);
	}
	}
	if (in_osfd != -1) {
	close(in_osfd);
	}
	if (out_osfd != -1 && out_osfd != in_osfd) {
	close(out_osfd);
	}
	if (err_osfd != -1 && err_osfd != in_osfd
	&& err_osfd != out_osfd) {
	close(err_osfd);
	}
	if (attr->currentDirectory) {
	if (chdir(attr->currentDirectory) < 0) {
	_exit(1); /* failed */
	}
	}
	}

	if (childEnvp) {
	(void)execve(path, argv, childEnvp);
	} else {
	/* Inherit the environment of the parent. */
	(void)execv(path, argv);
	}
	/* Whoops! It returned. That's a bad sign. */
	_exit(1);
	#endif /* !NTO */
	}

	if (newEnvp) {
	PR_DELETE(newEnvp);
	}

	#if defined(_PR_NATIVE_THREADS)
	PR_Lock(pr_wp.ml);
	if (0 == pr_wp.numProcs++) {
	PR_NotifyCondVar(pr_wp.cv);
	}
	PR_Unlock(pr_wp.ml);
	#endif
	return process;
	}

	#ifdef _PR_SHARE_CLONES

	struct pr_CreateProcOp {
	const char *path;
	char const argv;
	char const envp;
	const PRProcessAttr *attr;
	PRProcess *process;
	PRErrorCode prerror;
	PRInt32 oserror;
	PRBool done;
	PRCondVar *doneCV;
	struct pr_CreateProcOp *next;
	};

	PRProcess *
	_MD_CreateUnixProcess(
	const char *path,
	char const argv,
	char const envp,
	const PRProcessAttr *attr)
	{
	struct pr_CreateProcOp *op;
	PRProcess *proc;
	int rv;

	if (PR_CallOnce(&pr_wp.once, _MD_InitProcesses) == PR_FAILURE) {
	return NULL;
	}

	op = PR_NEW(struct pr_CreateProcOp);
	if (NULL == op) {
	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
	return NULL;
	}
	op->path = path;
	op->argv = argv;
	op->envp = envp;
	op->attr = attr;
	op->done = PR_FALSE;
	op->doneCV = PR_NewCondVar(pr_wp.ml);
	if (NULL == op->doneCV) {
	PR_DELETE(op);
	return NULL;
	}
	PR_Lock(pr_wp.ml);

	/* add to the tail of op queue */
	op->next = NULL;
	if (pr_wp.opTail) {
	pr_wp.opTail->next = op;
	pr_wp.opTail = op;
	} else {
	PR_ASSERT(NULL == pr_wp.opHead);
	pr_wp.opHead = pr_wp.opTail = op;
	}

	/* wake up the daemon thread */
	do {
	rv = write(pr_wp.pipefd[1], "", 1);
	} while (-1 == rv && EINTR == errno);

	while (op->done == PR_FALSE) {
	PR_WaitCondVar(op->doneCV, PR_INTERVAL_NO_TIMEOUT);
	}
	PR_Unlock(pr_wp.ml);
	PR_DestroyCondVar(op->doneCV);
	proc = op->process;
	if (!proc) {
	PR_SetError(op->prerror, op->oserror);
	}
	PR_DELETE(op);
	return proc;
	}

	#else /* ! _PR_SHARE_CLONES */

	PRProcess *
	_MD_CreateUnixProcess(
	const char *path,
	char const argv,
	char const envp,
	const PRProcessAttr *attr)
	{
	if (PR_CallOnce(&pr_wp.once, _MD_InitProcesses) == PR_FAILURE) {
	return NULL;
	}
	return ForkAndExec(path, argv, envp, attr);
	} /* _MD_CreateUnixProcess */

	#endif /* _PR_SHARE_CLONES */

	/*
	* The pid table is a hashtable.
	*
	* The number of buckets in the hashtable (NBUCKETS) must be a power of 2.
	*/
	#define NBUCKETS_LOG2 6
	#define NBUCKETS (1 << NBUCKETS_LOG2)
	#define PID_HASH_MASK ((pid_t) (NBUCKETS - 1))

	static pr_PidRecord *
	FindPidTable(pid_t pid)
	{
	pr_PidRecord *pRec;
	int keyHash = (int) (pid & PID_HASH_MASK);

	pRec = pr_wp.pidTable[keyHash];
	while (pRec) {
	if (pRec->pid == pid) {
	break;
	}
	pRec = pRec->next;
	}
	return pRec;
	}

	static void
	InsertPidTable(pr_PidRecord *pRec)
	{
	int keyHash = (int) (pRec->pid & PID_HASH_MASK);

	pRec->next = pr_wp.pidTable[keyHash];
	pr_wp.pidTable[keyHash] = pRec;
	}

	static void
	DeletePidTable(pr_PidRecord *pRec)
	{
	int keyHash = (int) (pRec->pid & PID_HASH_MASK);

	if (pr_wp.pidTable[keyHash] == pRec) {
	pr_wp.pidTable[keyHash] = pRec->next;
	} else {
	pr_PidRecord pred, cur; /* predecessor and current */

	pred = pr_wp.pidTable[keyHash];
	cur = pred->next;
	while (cur) {
	if (cur == pRec) {
	pred->next = cur->next;
	break;
	}
	pred = cur;
	cur = cur->next;
	}
	PR_ASSERT(cur != NULL);
	}
	}

	static int
	ExtractExitStatus(int rawExitStatus)
	{
	/*
	* We did not specify the WCONTINUED and WUNTRACED options
	* for waitpid, so these two events should not be reported.
	*/
	PR_ASSERT(!WIFSTOPPED(rawExitStatus));
	#ifdef WIFCONTINUED
	PR_ASSERT(!WIFCONTINUED(rawExitStatus));
	#endif
	if (WIFEXITED(rawExitStatus)) {
	return WEXITSTATUS(rawExitStatus);
	} else {
	PR_ASSERT(WIFSIGNALED(rawExitStatus));
	return _PR_SIGNALED_EXITSTATUS;
	}
	}

	static void
	ProcessReapedChildInternal(pid_t pid, int status)
	{
	pr_PidRecord *pRec;

	pRec = FindPidTable(pid);
	if (NULL == pRec) {
	pRec = PR_NEW(pr_PidRecord);
	pRec->pid = pid;
	pRec->state = _PR_PID_REAPED;
	pRec->exitStatus = ExtractExitStatus(status);
	pRec->reapedCV = NULL;
	InsertPidTable(pRec);
	} else {
	PR_ASSERT(pRec->state != _PR_PID_REAPED);
	if (_PR_PID_DETACHED == pRec->state) {
	PR_ASSERT(NULL == pRec->reapedCV);
	DeletePidTable(pRec);
	PR_DELETE(pRec);
	} else {
	PR_ASSERT(_PR_PID_WAITING == pRec->state);
	PR_ASSERT(NULL != pRec->reapedCV);
	pRec->exitStatus = ExtractExitStatus(status);
	pRec->state = _PR_PID_REAPED;
	PR_NotifyCondVar(pRec->reapedCV);
	}
	}
	}

	#if defined(_PR_NATIVE_THREADS)

	/*
	* If all the threads are native threads, the daemon thread is
	* simpler. We don't need to catch the SIGCHLD signal. We can
	* just have the daemon thread block in waitpid().
	*/

	static void WaitPidDaemonThread(void *unused)
	{
	pid_t pid;
	int status;

	while (1) {
	PR_Lock(pr_wp.ml);
	while (0 == pr_wp.numProcs) {
	PR_WaitCondVar(pr_wp.cv, PR_INTERVAL_NO_TIMEOUT);
	}
	PR_Unlock(pr_wp.ml);

	while (1) {
	do {
	pid = waitpid((pid_t) -1, &status, 0);
	} while ((pid_t) -1 == pid && EINTR == errno);

	/*
	* waitpid() cannot return 0 because we did not invoke it
	* with the WNOHANG option.
	*/
	PR_ASSERT(0 != pid);

	/*
	* The only possible error code is ECHILD. But if we do
	* our accounting correctly, we should only call waitpid()
	* when there is a child process to wait for.
	*/
	PR_ASSERT((pid_t) -1 != pid);
	if ((pid_t) -1 == pid) {
	break;
	}

	PR_Lock(pr_wp.ml);
	ProcessReapedChildInternal(pid, status);
	pr_wp.numProcs--;
	while (0 == pr_wp.numProcs) {
	PR_WaitCondVar(pr_wp.cv, PR_INTERVAL_NO_TIMEOUT);
	}
	PR_Unlock(pr_wp.ml);
	}
	}
	}

	#else /* _PR_NATIVE_THREADS */

	static void WaitPidDaemonThread(void *unused)
	{
	PRPollDesc pd;
	PRFileDesc *fd;
	int rv;
	char buf[128];
	pid_t pid;
	int status;
	#ifdef _PR_SHARE_CLONES
	struct pr_CreateProcOp *op;
	#endif

	#ifdef _PR_SHARE_CLONES
	pr_InstallSigchldHandler();
	#endif

	fd = PR_ImportFile(pr_wp.pipefd[0]);
	PR_ASSERT(NULL != fd);
	pd.fd = fd;
	pd.in_flags = PR_POLL_READ;

	while (1) {
	rv = PR_Poll(&pd, 1, PR_INTERVAL_NO_TIMEOUT);
	PR_ASSERT(1 == rv);

	#ifdef _PR_SHARE_CLONES
	if (pr_waitpid_daemon_exit) {
	return;
	}
	PR_Lock(pr_wp.ml);
	#endif

	do {
	rv = read(pr_wp.pipefd[0], buf, sizeof(buf));
	} while (sizeof(buf) == rv \|\| (-1 == rv && EINTR == errno));

	#ifdef _PR_SHARE_CLONES
	PR_Unlock(pr_wp.ml);
	while ((op = pr_wp.opHead) != NULL) {
	op->process = ForkAndExec(op->path, op->argv,
	op->envp, op->attr);
	if (NULL == op->process) {
	op->prerror = PR_GetError();
	op->oserror = PR_GetOSError();
	}
	PR_Lock(pr_wp.ml);
	pr_wp.opHead = op->next;
	if (NULL == pr_wp.opHead) {
	pr_wp.opTail = NULL;
	}
	op->done = PR_TRUE;
	PR_NotifyCondVar(op->doneCV);
	PR_Unlock(pr_wp.ml);
	}
	#endif

	while (1) {
	do {
	pid = waitpid((pid_t) -1, &status, WNOHANG);
	} while ((pid_t) -1 == pid && EINTR == errno);
	if (0 == pid) break;
	if ((pid_t) -1 == pid) {
	/* must be because we have no child processes */
	PR_ASSERT(ECHILD == errno);
	break;
	}

	PR_Lock(pr_wp.ml);
	ProcessReapedChildInternal(pid, status);
	PR_Unlock(pr_wp.ml);
	}
	}
	}

	static void pr_SigchldHandler(int sig)
	{
	int errnoCopy;
	int rv;

	errnoCopy = errno;

	do {
	rv = write(pr_wp.pipefd[1], "", 1);
	} while (-1 == rv && EINTR == errno);

	#ifdef DEBUG
	if (-1 == rv && EAGAIN != errno && EWOULDBLOCK != errno) {
	char *msg = "cannot write to pipe\n";
	write(2, msg, strlen(msg) + 1);
	_exit(1);
	}
	#endif

	errno = errnoCopy;
	}

	static void pr_InstallSigchldHandler()
	{
	#if defined(HPUX) && defined(_PR_DCETHREADS)
	#error "HP-UX DCE threads have their own SIGCHLD handler"
	#endif

	struct sigaction act, oact;
	int rv;

	act.sa_handler = pr_SigchldHandler;
	sigemptyset(&act.sa_mask);
	act.sa_flags = SA_NOCLDSTOP \| SA_RESTART;
	rv = sigaction(SIGCHLD, &act, &oact);
	PR_ASSERT(0 == rv);
	/* Make sure we are not overriding someone else's SIGCHLD handler */
	#ifndef _PR_SHARE_CLONES
	PR_ASSERT(oact.sa_handler == SIG_DFL);
	#endif
	}

	#endif /* !defined(_PR_NATIVE_THREADS) */

	static PRStatus _MD_InitProcesses(void)
	{
	#if !defined(_PR_NATIVE_THREADS)
	int rv;
	int flags;
	#endif
	#ifdef SUNOS4
	#define _PR_NBIO_FLAG FNDELAY
	#else
	#define _PR_NBIO_FLAG O_NONBLOCK
	#endif

	#ifdef AIX
	{
	void *handle = dlopen(NULL, RTLD_NOW \| RTLD_GLOBAL);
	pr_wp.forkptr = (pid_t (*)(void)) dlsym(handle, "f_fork");
	if (!pr_wp.forkptr) {
	pr_wp.forkptr = fork;
	}
	dlclose(handle);
	}
	#endif /* AIX */

	pr_wp.ml = PR_NewLock();
	PR_ASSERT(NULL != pr_wp.ml);

	#if defined(_PR_NATIVE_THREADS)
	pr_wp.numProcs = 0;
	pr_wp.cv = PR_NewCondVar(pr_wp.ml);
	PR_ASSERT(NULL != pr_wp.cv);
	#else
	rv = pipe(pr_wp.pipefd);
	PR_ASSERT(0 == rv);
	flags = fcntl(pr_wp.pipefd[0], F_GETFL, 0);
	fcntl(pr_wp.pipefd[0], F_SETFL, flags \| _PR_NBIO_FLAG);
	flags = fcntl(pr_wp.pipefd[1], F_GETFL, 0);
	fcntl(pr_wp.pipefd[1], F_SETFL, flags \| _PR_NBIO_FLAG);

	#ifndef _PR_SHARE_CLONES
	pr_InstallSigchldHandler();
	#endif
	#endif /* !_PR_NATIVE_THREADS */

	pr_wp.thread = PR_CreateThread(PR_SYSTEM_THREAD,
	WaitPidDaemonThread, NULL, PR_PRIORITY_NORMAL,
	#ifdef _PR_SHARE_CLONES
	PR_GLOBAL_THREAD,
	#else
	PR_LOCAL_THREAD,
	#endif
	PR_JOINABLE_THREAD, 0);
	PR_ASSERT(NULL != pr_wp.thread);

	pr_wp.pidTable = (pr_PidRecord*)PR_CALLOC(NBUCKETS sizeof(pr_PidRecord *));
	PR_ASSERT(NULL != pr_wp.pidTable);
	return PR_SUCCESS;
	}

	PRStatus _MD_DetachUnixProcess(PRProcess *process)
	{
	PRStatus retVal = PR_SUCCESS;
	pr_PidRecord *pRec;

	PR_Lock(pr_wp.ml);
	pRec = FindPidTable(process->md.pid);
	if (NULL == pRec) {
	pRec = PR_NEW(pr_PidRecord);
	if (NULL == pRec) {
	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
	retVal = PR_FAILURE;
	goto done;
	}
	pRec->pid = process->md.pid;
	pRec->state = _PR_PID_DETACHED;
	pRec->reapedCV = NULL;
	InsertPidTable(pRec);
	} else {
	PR_ASSERT(_PR_PID_REAPED == pRec->state);
	if (_PR_PID_REAPED != pRec->state) {
	PR_SetError(PR_INVALID_ARGUMENT_ERROR, 0);
	retVal = PR_FAILURE;
	} else {
	DeletePidTable(pRec);
	PR_ASSERT(NULL == pRec->reapedCV);
	PR_DELETE(pRec);
	}
	}
	PR_DELETE(process);

	done:
	PR_Unlock(pr_wp.ml);
	return retVal;
	}

	PRStatus _MD_WaitUnixProcess(
	PRProcess *process,
	PRInt32 *exitCode)
	{
	pr_PidRecord *pRec;
	PRStatus retVal = PR_SUCCESS;
	PRBool interrupted = PR_FALSE;

	PR_Lock(pr_wp.ml);
	pRec = FindPidTable(process->md.pid);
	if (NULL == pRec) {
	pRec = PR_NEW(pr_PidRecord);
	if (NULL == pRec) {
	PR_SetError(PR_OUT_OF_MEMORY_ERROR, 0);
	retVal = PR_FAILURE;
	goto done;
	}
	pRec->pid = process->md.pid;
	pRec->state = _PR_PID_WAITING;
	pRec->reapedCV = PR_NewCondVar(pr_wp.ml);
	if (NULL == pRec->reapedCV) {
	PR_DELETE(pRec);
	retVal = PR_FAILURE;
	goto done;
	}
	InsertPidTable(pRec);
	while (!interrupted && _PR_PID_REAPED != pRec->state) {
	if (PR_WaitCondVar(pRec->reapedCV,
	PR_INTERVAL_NO_TIMEOUT) == PR_FAILURE
	&& PR_GetError() == PR_PENDING_INTERRUPT_ERROR) {
	interrupted = PR_TRUE;
	}
	}
	if (_PR_PID_REAPED == pRec->state) {
	if (exitCode) {
	*exitCode = pRec->exitStatus;
	}
	} else {
	PR_ASSERT(interrupted);
	retVal = PR_FAILURE;
	}
	DeletePidTable(pRec);
	PR_DestroyCondVar(pRec->reapedCV);
	PR_DELETE(pRec);
	} else {
	PR_ASSERT(_PR_PID_REAPED == pRec->state);
	PR_ASSERT(NULL == pRec->reapedCV);
	DeletePidTable(pRec);
	if (exitCode) {
	*exitCode = pRec->exitStatus;
	}
	PR_DELETE(pRec);
	}
	PR_DELETE(process);

	done:
	PR_Unlock(pr_wp.ml);
	return retVal;
	} /* _MD_WaitUnixProcess */

	PRStatus _MD_KillUnixProcess(PRProcess *process)
	{
	PRErrorCode prerror;
	PRInt32 oserror;

	#ifdef SYMBIAN
	/* In Symbian OS, we can not kill other process with Open C */
	PR_SetError(PR_OPERATION_NOT_SUPPORTED_ERROR, oserror);
	return PR_FAILURE;
	#else
	if (kill(process->md.pid, SIGKILL) == 0) {
	return PR_SUCCESS;
	}
	oserror = errno;
	switch (oserror) {
	case EPERM:
	prerror = PR_NO_ACCESS_RIGHTS_ERROR;
	break;
	case ESRCH:
	prerror = PR_INVALID_ARGUMENT_ERROR;
	break;
	default:
	prerror = PR_UNKNOWN_ERROR;
	break;
	}
	PR_SetError(prerror, oserror);
	return PR_FAILURE;
	#endif
	} /* _MD_KillUnixProcess */