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tclWinPipe.c

/* 
 * tclWinPipe.c --
 *
 *    This file implements the Windows-specific exec pipeline functions,
 *    the "pipe" channel driver, and the "pid" Tcl command.
 *
 * Copyright (c) 1996-1997 by Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclWinPipe.c,v 1.3 1998/09/14 18:40:20 stanton Exp $
 */

#include "tclWinInt.h"

#include <dos.h>
#include <fcntl.h>
#include <io.h>
#include <sys/stat.h>

/*
 * The following variable is used to tell whether this module has been
 * initialized.
 */

static int initialized = 0;

/*
 * The following defines identify the various types of applications that 
 * run under windows.  There is special case code for the various types.
 */

#define APPL_NONE 0
#define APPL_DOS  1
#define APPL_WIN3X      2
#define APPL_WIN32      3

/*
 * The following constants and structures are used to encapsulate the state
 * of various types of files used in a pipeline.
 */

#define WIN32S_PIPE 1         /* Win32s emulated pipe. */
#define WIN32S_TMPFILE 2      /* Win32s emulated temporary file. */
#define WIN_FILE 3            /* Basic Win32 file. */

/*
 * This structure encapsulates the common state associated with all file
 * types used in a pipeline.
 */

typedef struct WinFile {
    int type;                 /* One of the file types defined above. */
    HANDLE handle;            /* Open file handle. */
} WinFile;

/*
 * The following structure is used to keep track of temporary files under
 * Win32s and delete the disk file when the open handle is closed.
 * The type field will be WIN32S_TMPFILE.
 */

typedef struct TmpFile {
    WinFile file;       /* Common part. */
    char name[MAX_PATH];      /* Name of temp file. */
} TmpFile;

/*
 * The following structure represents a synchronous pipe under Win32s.
 * The type field will be WIN32S_PIPE.  The handle field will refer to
 * an open file when Tcl is reading from the "pipe", otherwise it is
 * INVALID_HANDLE_VALUE.
 */

typedef struct WinPipe {
    WinFile file;       /* Common part. */
    struct WinPipe *otherPtr; /* Pointer to the WinPipe structure that
                         * corresponds to the other end of this 
                         * pipe. */
    char *fileName;           /* The name of the staging file that gets 
                         * the data written to this pipe.  Malloc'd.
                         * and shared by both ends of the pipe.  Only
                         * when both ends are freed will fileName be
                         * freed and the file it refers to deleted. */
} WinPipe;

/*
 * This list is used to map from pids to process handles.
 */

typedef struct ProcInfo {
    HANDLE hProcess;
    DWORD dwProcessId;
    struct ProcInfo *nextPtr;
} ProcInfo;

static ProcInfo *procList;

/*
 * State flags used in the PipeInfo structure below.
 */

#define PIPE_PENDING    (1<<0)      /* Message is pending in the queue. */
#define PIPE_ASYNC      (1<<1)      /* Channel is non-blocking. */

/*
 * This structure describes per-instance data for a pipe based channel.
 */

typedef struct PipeInfo {
    Tcl_Channel channel;      /* Pointer to channel structure. */
    int validMask;            /* OR'ed combination of TCL_READABLE,
                         * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                         * which operations are valid on the file. */
    int watchMask;            /* OR'ed combination of TCL_READABLE,
                         * TCL_WRITABLE, or TCL_EXCEPTION: indicates
                         * which events should be reported. */
    int flags;                /* State flags, see above for a list. */
    TclFile readFile;         /* Output from pipe. */
    TclFile writeFile;        /* Input from pipe. */
    TclFile errorFile;        /* Error output from pipe. */
    int numPids;        /* Number of processes attached to pipe. */
    Tcl_Pid *pidPtr;          /* Pids of attached processes. */
    struct PipeInfo *nextPtr; /* Pointer to next registered pipe. */
} PipeInfo;

/*
 * The following pointer refers to the head of the list of pipes
 * that are being watched for file events.
 */

static PipeInfo *firstPipePtr;

/*
 * The following structure is what is added to the Tcl event queue when
 * pipe events are generated.
 */

typedef struct PipeEvent {
    Tcl_Event header;         /* Information that is standard for
                         * all events. */
    PipeInfo *infoPtr;        /* Pointer to pipe info structure.  Note
                         * that we still have to verify that the
                         * pipe exists before dereferencing this
                         * pointer. */
} PipeEvent;

/*
 * Declarations for functions used only in this file.
 */

static int  ApplicationType(Tcl_Interp *interp, const char *fileName,
                char *fullName);
static void BuildCommandLine(int argc, char **argv, Tcl_DString *linePtr);
static void CopyChannel(HANDLE dst, HANDLE src);
static BOOL HasConsole(void);
static TclFile    MakeFile(HANDLE handle);
static char *     MakeTempFile(Tcl_DString *namePtr);
static int  PipeBlockModeProc(ClientData instanceData, int mode);
static void PipeCheckProc _ANSI_ARGS_((ClientData clientData,
                int flags));
static int  PipeCloseProc(ClientData instanceData, Tcl_Interp *interp);
static int  PipeEventProc(Tcl_Event *evPtr, int flags);
static void PipeExitHandler(ClientData clientData);
static int  PipeGetHandleProc(ClientData instanceData, int direction,
                ClientData *handlePtr);
static void PipeInit(void);
static int  PipeInputProc(ClientData instanceData, char *buf, int toRead,
                int *errorCode);
static int  PipeOutputProc(ClientData instanceData, char *buf, int toWrite,
                int *errorCode);
static void PipeWatchProc(ClientData instanceData, int mask);
static void PipeSetupProc _ANSI_ARGS_((ClientData clientData,
                int flags));
static int  TempFileName(char name[MAX_PATH]);

/*
 * This structure describes the channel type structure for command pipe
 * based IO.
 */

static Tcl_ChannelType pipeChannelType = {
    "pipe",             /* Type name. */
    PipeBlockModeProc,        /* Set blocking or non-blocking mode.*/
    PipeCloseProc,            /* Close proc. */
    PipeInputProc,            /* Input proc. */
    PipeOutputProc,           /* Output proc. */
    NULL,               /* Seek proc. */
    NULL,               /* Set option proc. */
    NULL,               /* Get option proc. */
    PipeWatchProc,            /* Set up notifier to watch the channel. */
    PipeGetHandleProc,        /* Get an OS handle from channel. */
};

/*
 *----------------------------------------------------------------------
 *
 * PipeInit --
 *
 *    This function initializes the static variables for this file.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Creates a new event source.
 *
 *----------------------------------------------------------------------
 */

static void
PipeInit()
{
    initialized = 1;
    firstPipePtr = NULL;
    procList = NULL;
    Tcl_CreateEventSource(PipeSetupProc, PipeCheckProc, NULL);
    Tcl_CreateExitHandler(PipeExitHandler, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * PipeExitHandler --
 *
 *    This function is called to cleanup the pipe module before
 *    Tcl is unloaded.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Removes the pipe event source.
 *
 *----------------------------------------------------------------------
 */

static void
PipeExitHandler(clientData)
    ClientData clientData;    /* Old window proc */
{
    Tcl_DeleteEventSource(PipeSetupProc, PipeCheckProc, NULL);
    initialized = 0;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeSetupProc --
 *
 *    This procedure is invoked before Tcl_DoOneEvent blocks waiting
 *    for an event.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Adjusts the block time if needed.
 *
 *----------------------------------------------------------------------
 */

void
PipeSetupProc(data, flags)
    ClientData data;          /* Not used. */
    int flags;                /* Event flags as passed to Tcl_DoOneEvent. */
{
    PipeInfo *infoPtr;
    Tcl_Time blockTime = { 0, 0 };

    if (!(flags & TCL_FILE_EVENTS)) {
      return;
    }
    
    /*
     * Check to see if there is a watched pipe.  If so, poll.
     */

    for (infoPtr = firstPipePtr; infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
      if (infoPtr->watchMask) {
          Tcl_SetMaxBlockTime(&blockTime);
          break;
      }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * PipeCheckProc --
 *
 *    This procedure is called by Tcl_DoOneEvent to check the pipe
 *    event source for events. 
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    May queue an event.
 *
 *----------------------------------------------------------------------
 */

static void
PipeCheckProc(data, flags)
    ClientData data;          /* Not used. */
    int flags;                /* Event flags as passed to Tcl_DoOneEvent. */
{
    PipeInfo *infoPtr;
    PipeEvent *evPtr;

    if (!(flags & TCL_FILE_EVENTS)) {
      return;
    }
    
    /*
     * Queue events for any watched pipes that don't already have events
     * queued.
     */

    for (infoPtr = firstPipePtr; infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
      if (infoPtr->watchMask && !(infoPtr->flags & PIPE_PENDING)) {
          infoPtr->flags |= PIPE_PENDING;
          evPtr = (PipeEvent *) ckalloc(sizeof(PipeEvent));
          evPtr->header.proc = PipeEventProc;
          evPtr->infoPtr = infoPtr;
          Tcl_QueueEvent((Tcl_Event *) evPtr, TCL_QUEUE_TAIL);
      }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * MakeFile --
 *
 *    This function constructs a new TclFile from a given data and
 *    type value.
 *
 * Results:
 *    Returns a newly allocated WinFile as a TclFile.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static TclFile
MakeFile(handle)
    HANDLE handle;            /* Type-specific data. */
{
    WinFile *filePtr;

    filePtr = (WinFile *) ckalloc(sizeof(WinFile));
    filePtr->type = WIN_FILE;
    filePtr->handle = handle;

    return (TclFile)filePtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpMakeFile --
 *
 *    Make a TclFile from a channel.
 *
 * Results:
 *    Returns a new TclFile or NULL on failure.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

TclFile
TclpMakeFile(channel, direction)
    Tcl_Channel channel;      /* Channel to get file from. */
    int direction;            /* Either TCL_READABLE or TCL_WRITABLE. */
{
    HANDLE handle;

    if (Tcl_GetChannelHandle(channel, direction, 
          (ClientData *) &handle) == TCL_OK) {
      return MakeFile(handle);
    } else {
      return (TclFile) NULL;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TempFileName --
 *
 *    Gets a temporary file name and deals with the fact that the
 *    temporary file path provided by Windows may not actually exist
 *    if the TMP or TEMP environment variables refer to a 
 *    non-existent directory.
 *
 * Results:    
 *    0 if error, non-zero otherwise.  If non-zero is returned, the
 *    name buffer will be filled with a name that can be used to 
 *    construct a temporary file.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static int
TempFileName(name)
    char name[MAX_PATH];      /* Buffer in which name for temporary 
                         * file gets stored. */
{
    if ((GetTempPath(MAX_PATH, name) == 0) ||
          (GetTempFileName(name, "TCL", 0, name) == 0)) {
      name[0] = '.';
      name[1] = '\0';
      if (GetTempFileName(name, "TCL", 0, name) == 0) {
          return 0;
      }
    }
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCreateTempFile --
 *
 *    This function opens a unique file with the property that it
 *    will be deleted when its file handle is closed.  The temporary
 *    file is created in the system temporary directory.
 *
 * Results:
 *    Returns a valid TclFile, or NULL on failure.
 *
 * Side effects:
 *    Creates a new temporary file.
 *
 *----------------------------------------------------------------------
 */

TclFile
TclpCreateTempFile(contents, namePtr)
    char *contents;           /* String to write into temp file, or NULL. */
    Tcl_DString *namePtr;     /* If non-NULL, pointer to initialized 
                         * DString that is filled with the name of 
                         * the temp file that was created. */
{
    char name[MAX_PATH];
    HANDLE handle;

    if (TempFileName(name) == 0) {
      return NULL;
    }

    handle = CreateFile(name, GENERIC_READ | GENERIC_WRITE, 0, NULL,
          CREATE_ALWAYS, FILE_ATTRIBUTE_TEMPORARY|FILE_FLAG_DELETE_ON_CLOSE,
          NULL);
    if (handle == INVALID_HANDLE_VALUE) {
      goto error;
    }

    /*
     * Write the file out, doing line translations on the way.
     */

    if (contents != NULL) {
      DWORD result, length;
      char *p;
      
      for (p = contents; *p != '\0'; p++) {
          if (*p == '\n') {
            length = p - contents;
            if (length > 0) {
                if (!WriteFile(handle, contents, length, &result, NULL)) {
                  goto error;
                }
            }
            if (!WriteFile(handle, "\r\n", 2, &result, NULL)) {
                goto error;
            }
            contents = p+1;
          }
      }
      length = p - contents;
      if (length > 0) {
          if (!WriteFile(handle, contents, length, &result, NULL)) {
            goto error;
          }
      }
    }

    if (SetFilePointer(handle, 0, NULL, FILE_BEGIN) == 0xFFFFFFFF) {
      goto error;
    }

    if (namePtr != NULL) {
        Tcl_DStringAppend(namePtr, name, -1);
    }

    /*
     * Under Win32s a file created with FILE_FLAG_DELETE_ON_CLOSE won't
     * actually be deleted when it is closed, so we have to do it ourselves.
     */

    if (TclWinGetPlatformId() == VER_PLATFORM_WIN32s) {
      TmpFile *tmpFilePtr = (TmpFile *) ckalloc(sizeof(TmpFile));
      tmpFilePtr->file.type = WIN32S_TMPFILE;
      tmpFilePtr->file.handle = handle;
      strcpy(tmpFilePtr->name, name);
      return (TclFile)tmpFilePtr;
    } else {
      return MakeFile(handle);
    }

  error:
    TclWinConvertError(GetLastError());
    CloseHandle(handle);
    DeleteFile(name);
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpOpenFile --
 *
 *    This function opens files for use in a pipeline.
 *
 * Results:
 *    Returns a newly allocated TclFile structure containing the
 *    file handle.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

TclFile
TclpOpenFile(path, mode)
    char *path;
    int mode;
{
    HANDLE handle;
    DWORD accessMode, createMode, shareMode, flags;
    SECURITY_ATTRIBUTES sec;

    /*
     * Map the access bits to the NT access mode.
     */

    switch (mode & (O_RDONLY | O_WRONLY | O_RDWR)) {
      case O_RDONLY:
          accessMode = GENERIC_READ;
          break;
      case O_WRONLY:
          accessMode = GENERIC_WRITE;
          break;
      case O_RDWR:
          accessMode = (GENERIC_READ | GENERIC_WRITE);
          break;
      default:
          TclWinConvertError(ERROR_INVALID_FUNCTION);
          return NULL;
    }

    /*
     * Map the creation flags to the NT create mode.
     */

    switch (mode & (O_CREAT | O_EXCL | O_TRUNC)) {
      case (O_CREAT | O_EXCL):
      case (O_CREAT | O_EXCL | O_TRUNC):
          createMode = CREATE_NEW;
          break;
      case (O_CREAT | O_TRUNC):
          createMode = CREATE_ALWAYS;
          break;
      case O_CREAT:
          createMode = OPEN_ALWAYS;
          break;
      case O_TRUNC:
      case (O_TRUNC | O_EXCL):
          createMode = TRUNCATE_EXISTING;
          break;
      default:
          createMode = OPEN_EXISTING;
          break;
    }

    /*
     * If the file is not being created, use the existing file attributes.
     */

    flags = 0;
    if (!(mode & O_CREAT)) {
      flags = GetFileAttributes(path);
      if (flags == 0xFFFFFFFF) {
          flags = 0;
      }
    }

    /*
     * Set up the security attributes so this file is not inherited by
     * child processes.
     */

    sec.nLength = sizeof(sec);
    sec.lpSecurityDescriptor = NULL;
    sec.bInheritHandle = 0;

    /*
     * Set up the file sharing mode.  We want to allow simultaneous access.
     */

    shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;

    /*
     * Now we get to create the file.
     */

    handle = CreateFile(path, accessMode, shareMode, &sec, createMode, flags,
            (HANDLE) NULL);
    if (handle == INVALID_HANDLE_VALUE) {
      DWORD err = GetLastError();
      if ((err & 0xffffL) == ERROR_OPEN_FAILED) {
          err = (mode & O_CREAT) ? ERROR_FILE_EXISTS : ERROR_FILE_NOT_FOUND;
      }
        TclWinConvertError(err);
        return NULL;
    }

    /*
     * Seek to the end of file if we are writing.
     */

    if (mode & O_WRONLY) {
      SetFilePointer(handle, 0, NULL, FILE_END);
    }

    return MakeFile(handle);
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCreatePipe --
 *
 *      Creates an anonymous pipe.  Under Win32s, creates a temp file
 *    that is used to simulate a pipe.
 *
 * Results:
 *      Returns 1 on success, 0 on failure. 
 *
 * Side effects:
 *      Creates a pipe.
 *
 *----------------------------------------------------------------------
 */

int
TclpCreatePipe(readPipe, writePipe)
    TclFile *readPipe;  /* Location to store file handle for
                         * read side of pipe. */
    TclFile *writePipe; /* Location to store file handle for
                         * write side of pipe. */
{
    HANDLE readHandle, writeHandle;

    if (CreatePipe(&readHandle, &writeHandle, NULL, 0) != 0) {
      *readPipe = MakeFile(readHandle);
      *writePipe = MakeFile(writeHandle);
      return 1;
    }

    if (TclWinGetPlatformId() == VER_PLATFORM_WIN32s) {
      WinPipe *readPipePtr, *writePipePtr;
      char buf[MAX_PATH];

      if (TempFileName(buf) != 0) {
          readPipePtr = (WinPipe *) ckalloc(sizeof(WinPipe));
          writePipePtr = (WinPipe *) ckalloc(sizeof(WinPipe));

          readPipePtr->file.type = WIN32S_PIPE;
          readPipePtr->otherPtr = writePipePtr;
          readPipePtr->fileName = strcpy(ckalloc(strlen(buf) + 1), buf);
          readPipePtr->file.handle = INVALID_HANDLE_VALUE;
          writePipePtr->file.type = WIN32S_PIPE;
          writePipePtr->otherPtr = readPipePtr;
          writePipePtr->fileName = readPipePtr->fileName;
          writePipePtr->file.handle = INVALID_HANDLE_VALUE;

          *readPipe = (TclFile)readPipePtr;
          *writePipe = (TclFile)writePipePtr;

          return 1;
      }
    }

    TclWinConvertError(GetLastError());
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCloseFile --
 *
 *    Closes a pipeline file handle.  These handles are created by
 *    TclpOpenFile, TclpCreatePipe, or TclpMakeFile.
 *
 * Results:
 *    0 on success, -1 on failure.
 *
 * Side effects:
 *    The file is closed and deallocated.
 *
 *----------------------------------------------------------------------
 */

int
TclpCloseFile(file)
    TclFile file; /* The file to close. */
{
    WinFile *filePtr = (WinFile *) file;
    WinPipe *pipePtr;

    switch (filePtr->type) {
      case WIN_FILE:
      case WIN32S_TMPFILE:
          if (CloseHandle(filePtr->handle) == FALSE) {
            TclWinConvertError(GetLastError());
            ckfree((char *) filePtr);
            return -1;
          }
          /*
           * Simulate deleting the file on close for Win32s.
           */

          if (filePtr->type == WIN32S_TMPFILE) {
            DeleteFile(((TmpFile*)filePtr)->name);
          }
          break;

      case WIN32S_PIPE:
          pipePtr = (WinPipe *) file;

          if (pipePtr->otherPtr != NULL) {
            pipePtr->otherPtr->otherPtr = NULL;
          } else {
            if (pipePtr->file.handle != INVALID_HANDLE_VALUE) {
                CloseHandle(pipePtr->file.handle);
            }
            DeleteFile(pipePtr->fileName);
            ckfree((char *) pipePtr->fileName);
          }
          break;

      default:
          panic("Tcl_CloseFile: unexpected file type");
    }

    ckfree((char *) filePtr);
    return 0;
}

/*
 *--------------------------------------------------------------------------
 *
 * TclpGetPid --
 *
 *    Given a HANDLE to a child process, return the process id for that
 *    child process.
 *
 * Results:
 *    Returns the process id for the child process.  If the pid was not 
 *    known by Tcl, either because the pid was not created by Tcl or the 
 *    child process has already been reaped, -1 is returned.
 *
 * Side effects:
 *    None.
 *
 *--------------------------------------------------------------------------
 */

unsigned long
TclpGetPid(pid)
    Tcl_Pid pid;        /* The HANDLE of the child process. */
{
    ProcInfo *infoPtr;
    
    for (infoPtr = procList; infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
      if (infoPtr->hProcess == (HANDLE) pid) {
          return infoPtr->dwProcessId;
      }
    }
    return (unsigned long) -1;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCreateProcess --
 *
 *    Create a child process that has the specified files as its 
 *    standard input, output, and error.  The child process runs
 *    synchronously under Win32s and asynchronously under Windows NT
 *    and Windows 95, and runs with the same environment variables
 *    as the creating process.
 *
 *    The complete Windows search path is searched to find the specified 
 *    executable.  If an executable by the given name is not found, 
 *    automatically tries appending ".com", ".exe", and ".bat" to the 
 *    executable name.
 *
 * Results:
 *    The return value is TCL_ERROR and an error message is left in
 *    interp->result if there was a problem creating the child 
 *    process.  Otherwise, the return value is TCL_OK and *pidPtr is
 *    filled with the process id of the child process.
 * 
 * Side effects:
 *    A process is created.
 *    
 *----------------------------------------------------------------------
 */

int
TclpCreateProcess(interp, argc, argv, inputFile, outputFile, errorFile, 
      pidPtr)
    Tcl_Interp *interp;       /* Interpreter in which to leave errors that
                         * occurred when creating the child process.
                         * Error messages from the child process
                         * itself are sent to errorFile. */
    int argc;                 /* Number of arguments in following array. */
    char **argv;        /* Array of argument strings.  argv[0]
                         * contains the name of the executable
                         * converted to native format (using the
                         * Tcl_TranslateFileName call).  Additional
                         * arguments have not been converted. */
    TclFile inputFile;        /* If non-NULL, gives the file to use as
                         * input for the child process.  If inputFile
                         * file is not readable or is NULL, the child
                         * will receive no standard input. */
    TclFile outputFile;       /* If non-NULL, gives the file that
                         * receives output from the child process.  If
                         * outputFile file is not writeable or is
                         * NULL, output from the child will be
                         * discarded. */
    TclFile errorFile;        /* If non-NULL, gives the file that
                         * receives errors from the child process.  If
                         * errorFile file is not writeable or is NULL,
                         * errors from the child will be discarded.
                         * errorFile may be the same as outputFile. */
    Tcl_Pid *pidPtr;          /* If this procedure is successful, pidPtr
                         * is filled with the process id of the child
                         * process. */
{
    int result, applType, createFlags;
    Tcl_DString cmdLine;
    STARTUPINFO startInfo;
    PROCESS_INFORMATION procInfo;
    SECURITY_ATTRIBUTES secAtts;
    HANDLE hProcess, h, inputHandle, outputHandle, errorHandle;
    char execPath[MAX_PATH];
    char *originalName;
    WinFile *filePtr;

    if (!initialized) {
      PipeInit();
    }

    applType = ApplicationType(interp, argv[0], execPath);
    if (applType == APPL_NONE) {
      return TCL_ERROR;
    }
    originalName = argv[0];
    argv[0] = execPath;

    result = TCL_ERROR;
    Tcl_DStringInit(&cmdLine);

    if (TclWinGetPlatformId() == VER_PLATFORM_WIN32s) {
      /*
       * Under Win32s, there are no pipes.  In order to simulate pipe
       * behavior, the child processes are run synchronously and their
       * I/O is redirected from/to temporary files before the next 
       * stage of the pipeline is started.
       */

      MSG msg;
      DWORD status;
      DWORD args[4];
      void *trans[5];
      char *inputFileName, *outputFileName;
      Tcl_DString inputTempFile, outputTempFile;

      BuildCommandLine(argc, argv, &cmdLine);

      ZeroMemory(&startInfo, sizeof(startInfo));
      startInfo.cb = sizeof(startInfo);

      Tcl_DStringInit(&inputTempFile);
      Tcl_DStringInit(&outputTempFile);
      outputHandle = INVALID_HANDLE_VALUE;

      inputFileName = NULL;
      outputFileName = NULL;
      if (inputFile != NULL) {
          filePtr = (WinFile *) inputFile;
          switch (filePtr->type) {
            case WIN_FILE:
            case WIN32S_TMPFILE: {
                h = INVALID_HANDLE_VALUE;
                inputFileName = MakeTempFile(&inputTempFile);
                if (inputFileName != NULL) {
                  h = CreateFile(inputFileName, GENERIC_WRITE, 0, 
                        NULL, CREATE_ALWAYS, 0, NULL);
                }
                if (h == INVALID_HANDLE_VALUE) {
                  Tcl_AppendResult(interp, "couldn't duplicate input handle: ", 
                        Tcl_PosixError(interp), (char *) NULL);
                  goto end32s;
                }
                CopyChannel(h, filePtr->handle);
                CloseHandle(h);
                break;
            }
            case WIN32S_PIPE: {
                inputFileName = ((WinPipe*)inputFile)->fileName;
                break;
            }
          }
      }
      if (inputFileName == NULL) {
          inputFileName = "nul";
      }
      if (outputFile != NULL) {
          filePtr = (WinFile *)outputFile;
          if (filePtr->type == WIN_FILE) {
            outputFileName = MakeTempFile(&outputTempFile);
            if (outputFileName == NULL) {
                Tcl_AppendResult(interp, "couldn't duplicate output handle: ",
                      Tcl_PosixError(interp), (char *) NULL);
                goto end32s;
            }
            outputHandle = filePtr->handle;
          } else if (filePtr->type == WIN32S_PIPE) {
            outputFileName = ((WinPipe*)outputFile)->fileName;
          }
      }
      if (outputFileName == NULL) {
          outputFileName = "nul";
      }

      if (applType == APPL_DOS) {
          args[0] = (DWORD) Tcl_DStringValue(&cmdLine);
          args[1] = (DWORD) inputFileName;
          args[2] = (DWORD) outputFileName;
          trans[0] = &args[0];
          trans[1] = &args[1];
          trans[2] = &args[2];
          trans[3] = NULL;
          if (TclWinSynchSpawn(args, 0, trans, pidPtr) != 0) {
            result = TCL_OK;
          }
      } else if (applType == APPL_WIN3X) {
          args[0] = (DWORD) Tcl_DStringValue(&cmdLine);
          trans[0] = &args[0];
          trans[1] = NULL;
          if (TclWinSynchSpawn(args, 1, trans, pidPtr) != 0) {
            result = TCL_OK;
          }
      } else {
          if (CreateProcess(NULL, Tcl_DStringValue(&cmdLine), NULL, NULL, 
                FALSE, DETACHED_PROCESS, NULL, NULL, &startInfo, 
                &procInfo) != 0) {
            CloseHandle(procInfo.hThread);
            while (1) {
                if (GetExitCodeProcess(procInfo.hProcess, &status) == FALSE) {
                  break;
                }
                if (status != STILL_ACTIVE) {
                  break;
                }
                if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) == TRUE) {
                  TranslateMessage(&msg);
                  DispatchMessage(&msg);
                }
            }
            *pidPtr = (Tcl_Pid) procInfo.hProcess;
            if (*pidPtr != 0) {
                ProcInfo *procPtr = (ProcInfo *) ckalloc(sizeof(ProcInfo));
                procPtr->hProcess = procInfo.hProcess;
                procPtr->dwProcessId = procInfo.dwProcessId;
                procPtr->nextPtr = procList;
                procList = procPtr;
            }
            result = TCL_OK;
          }
      }
      if (result != TCL_OK) {
          TclWinConvertError(GetLastError());
          Tcl_AppendResult(interp, "couldn't execute \"", originalName,
                "\": ", Tcl_PosixError(interp), (char *) NULL);
      }

      end32s:
      if (outputHandle != INVALID_HANDLE_VALUE) {
          /*
           * Now copy stuff from temp file to actual output handle. Don't
           * close outputHandle because it is associated with the output
           * file owned by the caller.
           */

          h = CreateFile(outputFileName, GENERIC_READ, 0, NULL, OPEN_ALWAYS,
                0, NULL);
          if (h != INVALID_HANDLE_VALUE) {
            CopyChannel(outputHandle, h);
          }
          CloseHandle(h);
      }

      if (inputFileName == Tcl_DStringValue(&inputTempFile)) {
          DeleteFile(inputFileName);
      }
      
      if (outputFileName == Tcl_DStringValue(&outputTempFile)) {
          DeleteFile(outputFileName);
      }

      Tcl_DStringFree(&inputTempFile);
      Tcl_DStringFree(&outputTempFile);
        Tcl_DStringFree(&cmdLine);
      return result;
    }
    hProcess = GetCurrentProcess();

    /*
     * STARTF_USESTDHANDLES must be used to pass handles to child process.
     * Using SetStdHandle() and/or dup2() only works when a console mode 
     * parent process is spawning an attached console mode child process.
     */

    ZeroMemory(&startInfo, sizeof(startInfo));
    startInfo.cb = sizeof(startInfo);
    startInfo.dwFlags   = STARTF_USESTDHANDLES;
    startInfo.hStdInput = INVALID_HANDLE_VALUE;
    startInfo.hStdOutput= INVALID_HANDLE_VALUE;
    startInfo.hStdError = INVALID_HANDLE_VALUE;

    secAtts.nLength = sizeof(SECURITY_ATTRIBUTES);
    secAtts.lpSecurityDescriptor = NULL;
    secAtts.bInheritHandle = TRUE;

    /*
     * We have to check the type of each file, since we cannot duplicate 
     * some file types.  
     */

    inputHandle = INVALID_HANDLE_VALUE;
    if (inputFile != NULL) {
      filePtr = (WinFile *)inputFile;
      if (filePtr->type == WIN_FILE) {
          inputHandle = filePtr->handle;
      }
    }
    outputHandle = INVALID_HANDLE_VALUE;
    if (outputFile != NULL) {
      filePtr = (WinFile *)outputFile;
      if (filePtr->type == WIN_FILE) {
          outputHandle = filePtr->handle;
      }
    }
    errorHandle = INVALID_HANDLE_VALUE;
    if (errorFile != NULL) {
      filePtr = (WinFile *)errorFile;
      if (filePtr->type == WIN_FILE) {
          errorHandle = filePtr->handle;
      }
    }

    /*
     * Duplicate all the handles which will be passed off as stdin, stdout
     * and stderr of the child process. The duplicate handles are set to
     * be inheritable, so the child process can use them.
     */

    if (inputHandle == INVALID_HANDLE_VALUE) {
      /* 
       * If handle was not set, stdin should return immediate EOF.
       * Under Windows95, some applications (both 16 and 32 bit!) 
       * cannot read from the NUL device; they read from console
       * instead.  When running tk, this is fatal because the child 
       * process would hang forever waiting for EOF from the unmapped 
       * console window used by the helper application.
       *
       * Fortunately, the helper application detects a closed pipe 
       * as an immediate EOF and can pass that information to the 
       * child process.
       */

      if (CreatePipe(&startInfo.hStdInput, &h, &secAtts, 0) != FALSE) {
          CloseHandle(h);
      }
    } else {
      DuplicateHandle(hProcess, inputHandle, hProcess, &startInfo.hStdInput,
            0, TRUE, DUPLICATE_SAME_ACCESS);
    }
    if (startInfo.hStdInput == INVALID_HANDLE_VALUE) {
      TclWinConvertError(GetLastError());
      Tcl_AppendResult(interp, "couldn't duplicate input handle: ",
            Tcl_PosixError(interp), (char *) NULL);
      goto end;
    }

    if (outputHandle == INVALID_HANDLE_VALUE) {
      /*
       * If handle was not set, output should be sent to an infinitely 
       * deep sink.  Under Windows 95, some 16 bit applications cannot
       * have stdout redirected to NUL; they send their output to
       * the console instead.  Some applications, like "more" or "dir /p", 
       * when outputting multiple pages to the console, also then try and
       * read from the console to go the next page.  When running tk, this
       * is fatal because the child process would hang forever waiting
       * for input from the unmapped console window used by the helper
       * application.
       *
       * Fortunately, the helper application will detect a closed pipe
       * as a sink.
       */

      if ((TclWinGetPlatformId() == VER_PLATFORM_WIN32_WINDOWS) 
            && (applType == APPL_DOS)) {
          if (CreatePipe(&h, &startInfo.hStdOutput, &secAtts, 0) != FALSE) {
            CloseHandle(h);
          }
      } else {
          startInfo.hStdOutput = CreateFile("NUL:", GENERIC_WRITE, 0,
                &secAtts, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
      }
    } else {
      DuplicateHandle(hProcess, outputHandle, hProcess, &startInfo.hStdOutput, 
            0, TRUE, DUPLICATE_SAME_ACCESS);
    }
    if (startInfo.hStdOutput == INVALID_HANDLE_VALUE) {
      TclWinConvertError(GetLastError());
      Tcl_AppendResult(interp, "couldn't duplicate output handle: ",
            Tcl_PosixError(interp), (char *) NULL);
      goto end;
    }

    if (errorHandle == INVALID_HANDLE_VALUE) {
      /*
       * If handle was not set, errors should be sent to an infinitely
       * deep sink.
       */

      startInfo.hStdError = CreateFile("NUL:", GENERIC_WRITE, 0,
            &secAtts, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
    } else {
      DuplicateHandle(hProcess, errorHandle, hProcess, &startInfo.hStdError, 
            0, TRUE, DUPLICATE_SAME_ACCESS);
    } 
    if (startInfo.hStdError == INVALID_HANDLE_VALUE) {
      TclWinConvertError(GetLastError());
      Tcl_AppendResult(interp, "couldn't duplicate error handle: ",
            Tcl_PosixError(interp), (char *) NULL);
      goto end;
    }
    /* 
     * If we do not have a console window, then we must run DOS and
     * WIN32 console mode applications as detached processes. This tells
     * the loader that the child application should not inherit the
     * console, and that it should not create a new console window for
     * the child application.  The child application should get its stdio 
     * from the redirection handles provided by this application, and run
     * in the background.
     *
     * If we are starting a GUI process, they don't automatically get a 
     * console, so it doesn't matter if they are started as foreground or
     * detached processes.  The GUI window will still pop up to the
     * foreground.
     */

    if (TclWinGetPlatformId() == VER_PLATFORM_WIN32_NT) {
      if (HasConsole()) {
          createFlags = 0;
      } else if (applType == APPL_DOS) {
          /*
           * Under NT, 16-bit DOS applications will not run unless they
           * can be attached to a console.  If we are running without a
           * console, run the 16-bit program as an normal process inside
           * of a hidden console application, and then run that hidden
           * console as a detached process.
           */

          startInfo.wShowWindow = SW_HIDE;
          startInfo.dwFlags |= STARTF_USESHOWWINDOW;
          createFlags = CREATE_NEW_CONSOLE;
          Tcl_DStringAppend(&cmdLine, "cmd.exe /c ", -1);
      } else {
          createFlags = DETACHED_PROCESS;
      } 
    } else {
      if (HasConsole()) {
          createFlags = 0;
      } else {
          createFlags = DETACHED_PROCESS;
      }
      
      if (applType == APPL_DOS) {
          /*
           * Under Windows 95, 16-bit DOS applications do not work well 
           * with pipes:
           *
           * 1. EOF on a pipe between a detached 16-bit DOS application 
           * and another application is not seen at the other
           * end of the pipe, so the listening process blocks forever on 
           * reads.  This inablity to detect EOF happens when either a 
           * 16-bit app or the 32-bit app is the listener.  
           *
           * 2. If a 16-bit DOS application (detached or not) blocks when 
           * writing to a pipe, it will never wake up again, and it
           * eventually brings the whole system down around it.
           *
           * The 16-bit application is run as a normal process inside
           * of a hidden helper console app, and this helper may be run
           * as a detached process.  If any of the stdio handles is
           * a pipe, the helper application accumulates information 
           * into temp files and forwards it to or from the DOS 
           * application as appropriate.  This means that DOS apps 
           * must receive EOF from a stdin pipe before they will actually
           * begin, and must finish generating stdout or stderr before 
           * the data will be sent to the next stage of the pipe.
           *
           * The helper app should be located in the same directory as
           * the tcl dll.
           */

          if (createFlags != 0) {
            startInfo.wShowWindow = SW_HIDE;
            startInfo.dwFlags |= STARTF_USESHOWWINDOW;
            createFlags = CREATE_NEW_CONSOLE;
          }
          Tcl_DStringAppend(&cmdLine, "tclpip" STRINGIFY(TCL_MAJOR_VERSION) 
                STRINGIFY(TCL_MINOR_VERSION) ".dll ", -1);
      }
    }
    
    /*
     * cmdLine gets the full command line used to invoke the executable,
     * including the name of the executable itself.  The command line
     * arguments in argv[] are stored in cmdLine separated by spaces. 
     * Special characters in individual arguments from argv[] must be 
     * quoted when being stored in cmdLine.
     *
     * When calling any application, bear in mind that arguments that 
     * specify a path name are not converted.  If an argument contains 
     * forward slashes as path separators, it may or may not be 
     * recognized as a path name, depending on the program.  In general,
     * most applications accept forward slashes only as option 
     * delimiters and backslashes only as paths.
     *
     * Additionally, when calling a 16-bit dos or windows application, 
     * all path names must use the short, cryptic, path format (e.g., 
     * using ab~1.def instead of "a b.default").  
     */

    BuildCommandLine(argc, argv, &cmdLine);

    if (!CreateProcess(NULL, Tcl_DStringValue(&cmdLine), NULL, NULL, TRUE, 
          createFlags, NULL, NULL, &startInfo, &procInfo)) {
      TclWinConvertError(GetLastError());
      Tcl_AppendResult(interp, "couldn't execute \"", originalName,
            "\": ", Tcl_PosixError(interp), (char *) NULL);
      goto end;
    }

    if (applType == APPL_DOS) {
      WaitForSingleObject(hProcess, 50);
    }

    /* 
     * "When an application spawns a process repeatedly, a new thread 
     * instance will be created for each process but the previous 
     * instances may not be cleaned up.  This results in a significant 
     * virtual memory loss each time the process is spawned.  If there 
     * is a WaitForInputIdle() call between CreateProcess() and
     * CloseHandle(), the problem does not occur." PSS ID Number: Q124121
     */

    WaitForInputIdle(procInfo.hProcess, 5000);
    CloseHandle(procInfo.hThread);

    *pidPtr = (Tcl_Pid) procInfo.hProcess;
    if (*pidPtr != 0) {
      ProcInfo *procPtr = (ProcInfo *) ckalloc(sizeof(ProcInfo));
      procPtr->hProcess = procInfo.hProcess;
      procPtr->dwProcessId = procInfo.dwProcessId;
      procPtr->nextPtr = procList;
      procList = procPtr;
    }
    result = TCL_OK;

    end:
    Tcl_DStringFree(&cmdLine);
    if (startInfo.hStdInput != INVALID_HANDLE_VALUE) {
        CloseHandle(startInfo.hStdInput);
    }
    if (startInfo.hStdOutput != INVALID_HANDLE_VALUE) {
        CloseHandle(startInfo.hStdOutput);
    }
    if (startInfo.hStdError != INVALID_HANDLE_VALUE) {
      CloseHandle(startInfo.hStdError);
    }
    return result;
}


/*
 *----------------------------------------------------------------------
 *
 * HasConsole --
 *
 *    Determines whether the current application is attached to a
 *    console.
 *
 * Results:
 *    Returns TRUE if this application has a console, else FALSE.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static BOOL
HasConsole()
{
    HANDLE handle = CreateFile("CONOUT$", GENERIC_WRITE, FILE_SHARE_WRITE,
          NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

    if (handle != INVALID_HANDLE_VALUE) {
        CloseHandle(handle);
      return TRUE;
    } else {
        return FALSE;
    }
}

/*
 *--------------------------------------------------------------------
 *
 * ApplicationType --
 *
 *    Search for the specified program and identify if it refers to a DOS,
 *    Windows 3.X, or Win32 program.  Used to determine how to invoke 
 *    a program, or if it can even be invoked.
 *
 *    It is possible to almost positively identify DOS and Windows 
 *    applications that contain the appropriate magic numbers.  However, 
 *    DOS .com files do not seem to contain a magic number; if the program 
 *    name ends with .com and could not be identified as a Windows .com
 *    file, it will be assumed to be a DOS application, even if it was
 *    just random data.  If the program name does not end with .com, no 
 *    such assumption is made.
 *
 *    The Win32 procedure GetBinaryType incorrectly identifies any 
 *    junk file that ends with .exe as a dos executable and some 
 *    executables that don't end with .exe as not executable.  Plus it 
 *    doesn't exist under win95, so I won't feel bad about reimplementing
 *    functionality.
 *
 * Results:
 *    The return value is one of APPL_DOS, APPL_WIN3X, or APPL_WIN32
 *    if the filename referred to the corresponding application type.
 *    If the file name could not be found or did not refer to any known 
 *    application type, APPL_NONE is returned and an error message is 
 *    left in interp.  .bat files are identified as APPL_DOS.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static int
ApplicationType(interp, originalName, fullPath)
    Tcl_Interp *interp;       /* Interp, for error message. */
    const char *originalName; /* Name of the application to find. */
    char fullPath[MAX_PATH];  /* Filled with complete path to 
                         * application. */
{
    int applType, i;
    HANDLE hFile;
    char *ext, *rest;
    char buf[2];
    DWORD read;
    IMAGE_DOS_HEADER header;
    static char extensions[][5] = {"", ".com", ".exe", ".bat"};

    /* Look for the program as an external program.  First try the name
     * as it is, then try adding .com, .exe, and .bat, in that order, to
     * the name, looking for an executable.
     *
     * Using the raw SearchPath() procedure doesn't do quite what is 
     * necessary.  If the name of the executable already contains a '.' 
     * character, it will not try appending the specified extension when
     * searching (in other words, SearchPath will not find the program 
     * "a.b.exe" if the arguments specified "a.b" and ".exe").   
     * So, first look for the file as it is named.  Then manually append 
     * the extensions, looking for a match.  
     */

    applType = APPL_NONE;
    for (i = 0; i < (int) (sizeof(extensions) / sizeof(extensions[0])); i++) {
      lstrcpyn(fullPath, originalName, MAX_PATH - 5);
        lstrcat(fullPath, extensions[i]);
      
      SearchPath(NULL, fullPath, NULL, MAX_PATH, fullPath, &rest);

      /*
       * Ignore matches on directories or data files, return if identified
       * a known type.
       */

      if (GetFileAttributes(fullPath) & FILE_ATTRIBUTE_DIRECTORY) {
          continue;
      }

      ext = strrchr(fullPath, '.');
      if ((ext != NULL) && (strcmpi(ext, ".bat") == 0)) {
          applType = APPL_DOS;
          break;
      }

      hFile = CreateFile(fullPath, GENERIC_READ, FILE_SHARE_READ, NULL, 
            OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
      if (hFile == INVALID_HANDLE_VALUE) {
          continue;
      }

      header.e_magic = 0;
      ReadFile(hFile, (void *) &header, sizeof(header), &read, NULL);
      if (header.e_magic != IMAGE_DOS_SIGNATURE) {
          /* 
           * Doesn't have the magic number for relocatable executables.  If 
           * filename ends with .com, assume it's a DOS application anyhow.
           * Note that we didn't make this assumption at first, because some
           * supposed .com files are really 32-bit executables with all the
           * magic numbers and everything.  
           */

          CloseHandle(hFile);
          if ((ext != NULL) && (strcmpi(ext, ".com") == 0)) {
            applType = APPL_DOS;
            break;
          }
          continue;
      }
      if (header.e_lfarlc != sizeof(header)) {
          /* 
           * All Windows 3.X and Win32 and some DOS programs have this value
           * set here.  If it doesn't, assume that since it already had the 
           * other magic number it was a DOS application.
           */

          CloseHandle(hFile);
          applType = APPL_DOS;
          break;
      }

      /* 
       * The DWORD at header.e_lfanew points to yet another magic number.
       */

      buf[0] = '\0';
      SetFilePointer(hFile, header.e_lfanew, NULL, FILE_BEGIN);
      ReadFile(hFile, (void *) buf, 2, &read, NULL);
      CloseHandle(hFile);

      if ((buf[0] == 'N') && (buf[1] == 'E')) {
          applType = APPL_WIN3X;
      } else if ((buf[0] == 'P') && (buf[1] == 'E')) {
          applType = APPL_WIN32;
      } else {
          /*
           * Strictly speaking, there should be a test that there
           * is an 'L' and 'E' at buf[0..1], to identify the type as 
           * DOS, but of course we ran into a DOS executable that 
           * _doesn't_ have the magic number -- specifically, one
           * compiled using the Lahey Fortran90 compiler.
           */

          applType = APPL_DOS;
      }
      break;
    }

    if (applType == APPL_NONE) {
      TclWinConvertError(GetLastError());
      Tcl_AppendResult(interp, "couldn't execute \"", originalName,
            "\": ", Tcl_PosixError(interp), (char *) NULL);
      return APPL_NONE;
    }

    if ((applType == APPL_DOS) || (applType == APPL_WIN3X)) {
      /* 
       * Replace long path name of executable with short path name for 
       * 16-bit applications.  Otherwise the application may not be able
       * to correctly parse its own command line to separate off the 
       * application name from the arguments.
       */

      GetShortPathName(fullPath, fullPath, MAX_PATH);
    }
    return applType;
}

/*    
 *----------------------------------------------------------------------
 *
 * BuildCommandLine --
 *
 *    The command line arguments are stored in linePtr separated
 *    by spaces, in a form that CreateProcess() understands.  Special 
 *    characters in individual arguments from argv[] must be quoted 
 *    when being stored in cmdLine.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static void
BuildCommandLine(argc, argv, linePtr)
    int argc;                 /* Number of arguments. */
    char **argv;        /* Argument strings. */
    Tcl_DString *linePtr;     /* Initialized Tcl_DString that receives the
                         * command line. */
{
    char *start, *special;
    int quote, i;

    for (i = 0; i < argc; i++) {
      if (i > 0) {
          Tcl_DStringAppend(linePtr, " ", 1);   
      }

      quote = 0;
      if (argv[i][0] == '\0') {
          quote = 1;
      } else {
          for (start = argv[i]; *start != '\0'; start++) {
            if (isspace(*start)) {
                quote = 1;
                break;
            }
          }
      }
      if (quote) {
          Tcl_DStringAppend(linePtr, "\"", 1);
      }

      start = argv[i];      
      for (special = argv[i]; ; ) {
          if ((*special == '\\') && 
                (special[1] == '\\' || special[1] == '"')) {
            Tcl_DStringAppend(linePtr, start, special - start);
            start = special;
            while (1) {
                special++;
                if (*special == '"') {
                  /* 
                   * N backslashes followed a quote -> insert 
                   * N * 2 + 1 backslashes then a quote.
                   */

                  Tcl_DStringAppend(linePtr, start, special - start);
                  break;
                }
                if (*special != '\\') {
                  break;
                }
            }
            Tcl_DStringAppend(linePtr, start, special - start);
            start = special;
          }
          if (*special == '"') {
            Tcl_DStringAppend(linePtr, start, special - start);
            Tcl_DStringAppend(linePtr, "\\\"", 2);
            start = special + 1;
          }
          if (*special == '\0') {
            break;
          }
          special++;
      }
      Tcl_DStringAppend(linePtr, start, special - start);
      if (quote) {
          Tcl_DStringAppend(linePtr, "\"", 1);
      }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * MakeTempFile --
 *
 *    Helper function for TclpCreateProcess under Win32s.  Makes a 
 *    temporary file that _won't_ go away automatically when it's file
 *    handle is closed.  Used for simulated pipes, which are written
 *    in one pass and reopened and read in the next pass.
 *
 * Results:
 *    namePtr is filled with the name of the temporary file.
 *
 * Side effects:
 *    A temporary file with the name specified by namePtr is created.  
 *    The caller is responsible for deleting this temporary file.
 *
 *----------------------------------------------------------------------
 */

static char *
MakeTempFile(namePtr)
    Tcl_DString *namePtr;     /* Initialized Tcl_DString that is filled 
                         * with the name of the temporary file that 
                         * was created. */
{
    char name[MAX_PATH];

    if (TempFileName(name) == 0) {
      return NULL;
    }

    Tcl_DStringAppend(namePtr, name, -1);
    return Tcl_DStringValue(namePtr);
}

/*
 *----------------------------------------------------------------------
 *
 * CopyChannel --
 *
 *    Helper function used by TclpCreateProcess under Win32s.  Copies
 *    what remains of source file to destination file; source file 
 *    pointer need not be positioned at the beginning of the file if
 *    all of source file is not desired, but data is copied up to end 
 *    of source file.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static void
CopyChannel(dst, src)
    HANDLE dst;               /* Destination file. */
    HANDLE src;               /* Source file. */
{
    char buf[8192];
    DWORD dwRead, dwWrite;

    while (ReadFile(src, buf, sizeof(buf), &dwRead, NULL) != FALSE) {
      if (dwRead == 0) {
          break;
      }
      if (WriteFile(dst, buf, dwRead, &dwWrite, NULL) == FALSE) {
          break;
      }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCreateCommandChannel --
 *
 *    This function is called by Tcl_OpenCommandChannel to perform
 *    the platform specific channel initialization for a command
 *    channel.
 *
 * Results:
 *    Returns a new channel or NULL on failure.
 *
 * Side effects:
 *    Allocates a new channel.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
TclpCreateCommandChannel(readFile, writeFile, errorFile, numPids, pidPtr)
    TclFile readFile;         /* If non-null, gives the file for reading. */
    TclFile writeFile;        /* If non-null, gives the file for writing. */
    TclFile errorFile;        /* If non-null, gives the file where errors
                         * can be read. */
    int numPids;        /* The number of pids in the pid array. */
    Tcl_Pid *pidPtr;          /* An array of process identifiers. */
{
    char channelName[20];
    int channelId;
    PipeInfo *infoPtr = (PipeInfo *) ckalloc((unsigned) sizeof(PipeInfo));

    if (!initialized) {
      PipeInit();
    }

    infoPtr->watchMask = 0;
    infoPtr->flags = 0;
    infoPtr->readFile = readFile;
    infoPtr->writeFile = writeFile;
    infoPtr->errorFile = errorFile;
    infoPtr->numPids = numPids;
    infoPtr->pidPtr = pidPtr;

    /*
     * Use one of the fds associated with the channel as the
     * channel id.
     */

    if (readFile) {
      WinPipe *pipePtr = (WinPipe *) readFile;
      if (pipePtr->file.type == WIN32S_PIPE
            && pipePtr->file.handle == INVALID_HANDLE_VALUE) {
          pipePtr->file.handle = CreateFile(pipePtr->fileName, GENERIC_READ,
                0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
      }
      channelId = (int) pipePtr->file.handle;
    } else if (writeFile) {
      channelId = (int) ((WinFile*)writeFile)->handle;
    } else if (errorFile) {
      channelId = (int) ((WinFile*)errorFile)->handle;
    } else {
      channelId = 0;
    }

    infoPtr->validMask = 0;
    if (readFile != NULL) {
        infoPtr->validMask |= TCL_READABLE;
    }
    if (writeFile != NULL) {
        infoPtr->validMask |= TCL_WRITABLE;
    }

    /*
     * For backward compatibility with previous versions of Tcl, we
     * use "file%d" as the base name for pipes even though it would
     * be more natural to use "pipe%d".
     */

    sprintf(channelName, "file%d", channelId);
    infoPtr->channel = Tcl_CreateChannel(&pipeChannelType, channelName,
            (ClientData) infoPtr, infoPtr->validMask);

    /*
     * Pipes have AUTO translation mode on Windows and ^Z eof char, which
     * means that a ^Z will be appended to them at close. This is needed
     * for Windows programs that expect a ^Z at EOF.
     */

    Tcl_SetChannelOption((Tcl_Interp *) NULL, infoPtr->channel,
          "-translation", "auto");
    Tcl_SetChannelOption((Tcl_Interp *) NULL, infoPtr->channel,
          "-eofchar", "\032 {}");
    return infoPtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * TclGetAndDetachPids --
 *
 *    Stores a list of the command PIDs for a command channel in
 *    interp->result.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    Modifies interp->result.
 *
 *----------------------------------------------------------------------
 */

void
TclGetAndDetachPids(interp, chan)
    Tcl_Interp *interp;
    Tcl_Channel chan;
{
    PipeInfo *pipePtr;
    Tcl_ChannelType *chanTypePtr;
    int i;
    char buf[20];

    /*
     * Punt if the channel is not a command channel.
     */

    chanTypePtr = Tcl_GetChannelType(chan);
    if (chanTypePtr != &pipeChannelType) {
        return;
    }

    pipePtr = (PipeInfo *) Tcl_GetChannelInstanceData(chan);
    for (i = 0; i < pipePtr->numPids; i++) {
        sprintf(buf, "%lu", TclpGetPid(pipePtr->pidPtr[i]));
        Tcl_AppendElement(interp, buf);
        Tcl_DetachPids(1, &(pipePtr->pidPtr[i]));
    }
    if (pipePtr->numPids > 0) {
        ckfree((char *) pipePtr->pidPtr);
        pipePtr->numPids = 0;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * PipeBlockModeProc --
 *
 *    Set blocking or non-blocking mode on channel.
 *
 * Results:
 *    0 if successful, errno when failed.
 *
 * Side effects:
 *    Sets the device into blocking or non-blocking mode.
 *
 *----------------------------------------------------------------------
 */

static int
PipeBlockModeProc(instanceData, mode)
    ClientData instanceData;  /* Instance data for channel. */
    int mode;                 /* TCL_MODE_BLOCKING or
                                 * TCL_MODE_NONBLOCKING. */
{
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    
    /*
     * Pipes on Windows can not be switched between blocking and nonblocking,
     * hence we have to emulate the behavior. This is done in the input
     * function by checking against a bit in the state. We set or unset the
     * bit here to cause the input function to emulate the correct behavior.
     */

    if (mode == TCL_MODE_NONBLOCKING) {
      infoPtr->flags |= PIPE_ASYNC;
    } else {
      infoPtr->flags &= ~(PIPE_ASYNC);
    }
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeCloseProc --
 *
 *    Closes a pipe based IO channel.
 *
 * Results:
 *    0 on success, errno otherwise.
 *
 * Side effects:
 *    Closes the physical channel.
 *
 *----------------------------------------------------------------------
 */

static int
PipeCloseProc(instanceData, interp)
    ClientData instanceData;  /* Pointer to PipeInfo structure. */
    Tcl_Interp *interp;       /* For error reporting. */
{
    PipeInfo *pipePtr = (PipeInfo *) instanceData;
    Tcl_Channel errChan;
    int errorCode, result;
    PipeInfo *infoPtr, **nextPtrPtr;

    /*
     * Remove the file from the list of watched files.
     */

    for (nextPtrPtr = &firstPipePtr, infoPtr = *nextPtrPtr; infoPtr != NULL;
          nextPtrPtr = &infoPtr->nextPtr, infoPtr = *nextPtrPtr) {
      if (infoPtr == (PipeInfo *)pipePtr) {
          *nextPtrPtr = infoPtr->nextPtr;
          break;
      }
    }

    errorCode = 0;
    if (pipePtr->readFile != NULL) {
      if (TclpCloseFile(pipePtr->readFile) != 0) {
          errorCode = errno;
      }
    }
    if (pipePtr->writeFile != NULL) {
      if (TclpCloseFile(pipePtr->writeFile) != 0) {
          if (errorCode == 0) {
            errorCode = errno;
          }
      }
    }
    
    /*
     * Wrap the error file into a channel and give it to the cleanup
     * routine.  If we are running in Win32s, just delete the error file
     * immediately, because it was never used.
     */

    if (pipePtr->errorFile) {
      WinFile *filePtr;
      OSVERSIONINFO os;

      os.dwOSVersionInfoSize = sizeof(os);
      GetVersionEx(&os);
      if (os.dwPlatformId == VER_PLATFORM_WIN32s) {
          TclpCloseFile(pipePtr->errorFile);
          errChan = NULL;
      } else {
          filePtr = (WinFile*)pipePtr->errorFile;
          errChan = Tcl_MakeFileChannel((ClientData) filePtr->handle,
                TCL_READABLE);
      }
    } else {
        errChan = NULL;
    }
    result = TclCleanupChildren(interp, pipePtr->numPids, pipePtr->pidPtr,
            errChan);
    if (pipePtr->numPids > 0) {
        ckfree((char *) pipePtr->pidPtr);
    }
    ckfree((char*) pipePtr);

    if (errorCode == 0) {
        return result;
    }
    return errorCode;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeInputProc --
 *
 *    Reads input from the IO channel into the buffer given. Returns
 *    count of how many bytes were actually read, and an error indication.
 *
 * Results:
 *    A count of how many bytes were read is returned and an error
 *    indication is returned in an output argument.
 *
 * Side effects:
 *    Reads input from the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
PipeInputProc(instanceData, buf, bufSize, errorCode)
    ClientData instanceData;        /* Pipe state. */
    char *buf;                      /* Where to store data read. */
    int bufSize;              /* How much space is available
                                         * in the buffer? */
    int *errorCode;                 /* Where to store error code. */
{
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    WinFile *filePtr = (WinFile*) infoPtr->readFile;
    DWORD count;
    DWORD bytesRead;

    *errorCode = 0;
    if (filePtr->type == WIN32S_PIPE) {
      if (((WinPipe *)filePtr)->otherPtr != NULL) {
          panic("PipeInputProc: child process isn't finished writing");
      }
      if (filePtr->handle == INVALID_HANDLE_VALUE) {
          filePtr->handle = CreateFile(((WinPipe *)filePtr)->fileName,
                GENERIC_READ, 0, NULL, OPEN_ALWAYS, FILE_ATTRIBUTE_NORMAL,
                NULL);
      }
      if (filePtr->handle == INVALID_HANDLE_VALUE) {
          goto error;
      }
    } else {
      /*
       * Pipes will block until the requested number of bytes has been
       * read.  To avoid blocking unnecessarily, we look ahead and only
       * read as much as is available.
       */

      if (PeekNamedPipe(filePtr->handle, (LPVOID) NULL, (DWORD) 0,
            (LPDWORD) NULL, &count, (LPDWORD) NULL) == TRUE) {
          if ((count != 0) && ((DWORD) bufSize > count)) {
            bufSize = (int) count;

            /*
             * This code is commented out because on Win95 we don't get
             * notifier of eof on a pipe unless we try to read it.
             * The correct solution is to move to threads.
             */

/*        } else if ((count == 0) && (infoPtr->flags & PIPE_ASYNC)) { */
/*          errno = *errorCode = EAGAIN; */
/*          return -1; */
          } else if ((count == 0) && !(infoPtr->flags & PIPE_ASYNC)) {
            bufSize = 1;
          }
      } else {
          goto error;
      }
    }

    /*
     * Note that we will block on reads from a console buffer until a
     * full line has been entered.  The only way I know of to get
     * around this is to write a console driver.  We should probably
     * do this at some point, but for now, we just block.
     */

    if (ReadFile(filePtr->handle, (LPVOID) buf, (DWORD) bufSize, &bytesRead,
            (LPOVERLAPPED) NULL) == FALSE) {
      goto error;
    }
    
    return bytesRead;

    error:
    TclWinConvertError(GetLastError());
    if (errno == EPIPE) {
      return 0;
    }
    *errorCode = errno;
    return -1;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeOutputProc --
 *
 *    Writes the given output on the IO channel. Returns count of how
 *    many characters were actually written, and an error indication.
 *
 * Results:
 *    A count of how many characters were written is returned and an
 *    error indication is returned in an output argument.
 *
 * Side effects:
 *    Writes output on the actual channel.
 *
 *----------------------------------------------------------------------
 */

static int
PipeOutputProc(instanceData, buf, toWrite, errorCode)
    ClientData instanceData;        /* Pipe state. */
    char *buf;                      /* The data buffer. */
    int toWrite;              /* How many bytes to write? */
    int *errorCode;                 /* Where to store error code. */
{
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    WinFile *filePtr = (WinFile*) infoPtr->writeFile;
    DWORD bytesWritten;
    
    *errorCode = 0;
    if (WriteFile(filePtr->handle, (LPVOID) buf, (DWORD) toWrite,
          &bytesWritten, (LPOVERLAPPED) NULL) == FALSE) {
        TclWinConvertError(GetLastError());
        if (errno == EPIPE) {
            return 0;
        }
        *errorCode = errno;
        return -1;
    }
    return bytesWritten;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeEventProc --
 *
 *    This function is invoked by Tcl_ServiceEvent when a file event
 *    reaches the front of the event queue.  This procedure invokes
 *    Tcl_NotifyChannel on the pipe.
 *
 * Results:
 *    Returns 1 if the event was handled, meaning it should be removed
 *    from the queue.  Returns 0 if the event was not handled, meaning
 *    it should stay on the queue.  The only time the event isn't
 *    handled is if the TCL_FILE_EVENTS flag bit isn't set.
 *
 * Side effects:
 *    Whatever the notifier callback does.
 *
 *----------------------------------------------------------------------
 */

static int
PipeEventProc(evPtr, flags)
    Tcl_Event *evPtr;         /* Event to service. */
    int flags;                /* Flags that indicate what events to
                         * handle, such as TCL_FILE_EVENTS. */
{
    PipeEvent *pipeEvPtr = (PipeEvent *)evPtr;
    PipeInfo *infoPtr;
    WinFile *filePtr;
    int mask;
/*    DWORD count;*/

    if (!(flags & TCL_FILE_EVENTS)) {
      return 0;
    }

    /*
     * Search through the list of watched pipes for the one whose handle
     * matches the event.  We do this rather than simply dereferencing
     * the handle in the event so that pipes can be deleted while the
     * event is in the queue.
     */

    for (infoPtr = firstPipePtr; infoPtr != NULL; infoPtr = infoPtr->nextPtr) {
      if (pipeEvPtr->infoPtr == infoPtr) {
          infoPtr->flags &= ~(PIPE_PENDING);
          break;
      }
    }

    /*
     * Remove stale events.
     */

    if (!infoPtr) {
      return 1;
    }

    /*
     * If we aren't on Win32s, check to see if the pipe is readable.  Note
     * that we can't tell if a pipe is writable, so we always report it
     * as being writable.
     */

    filePtr = (WinFile*) ((PipeInfo*)infoPtr)->readFile;
    if (filePtr->type != WIN32S_PIPE) {

      /*
       * On windows 95, PeekNamedPipe returns 0 on eof so we can't
       * distinguish underflow from eof.  The correct solution is to
       * switch to the threaded implementation.
       */
      mask = TCL_WRITABLE|TCL_READABLE;
/*    if (PeekNamedPipe(filePtr->handle, (LPVOID) NULL, (DWORD) 0, */
/*          (LPDWORD) NULL, &count, (LPDWORD) NULL) == TRUE) { */
/*        if (count != 0) { */
/*          mask |= TCL_READABLE; */
/*        } */
/*    } else { */

          /*
           * If the pipe has been closed by the other side, then 
           * mark the pipe as readable, but not writable.
           */

/*        if (GetLastError() == ERROR_BROKEN_PIPE) { */
/*          mask = TCL_READABLE; */
/*        } */
/*    } */
    } else {
      mask = TCL_READABLE | TCL_WRITABLE;
    }

    /*
     * Inform the channel of the events.
     */

    Tcl_NotifyChannel(infoPtr->channel, infoPtr->watchMask & mask);
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * PipeWatchProc --
 *
 *    Called by the notifier to set up to watch for events on this
 *    channel.
 *
 * Results:
 *    None.
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static void
PipeWatchProc(instanceData, mask)
    ClientData instanceData;        /* Pipe state. */
    int mask;                       /* What events to watch for; OR-ed
                                         * combination of TCL_READABLE,
                                         * TCL_WRITABLE and TCL_EXCEPTION. */
{
    PipeInfo **nextPtrPtr, *ptr;
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    int oldMask = infoPtr->watchMask;

    /*
     * For now, we just send a message to ourselves so we can poll the
     * channel for readable events.
     */

    infoPtr->watchMask = mask & infoPtr->validMask;
    if (infoPtr->watchMask) {
      Tcl_Time blockTime = { 0, 0 };
      if (!oldMask) {
          infoPtr->nextPtr = firstPipePtr;
          firstPipePtr = infoPtr;
      }
      Tcl_SetMaxBlockTime(&blockTime);
    } else {
      if (oldMask) {
          /*
           * Remove the pipe from the list of watched pipes.
           */

          for (nextPtrPtr = &firstPipePtr, ptr = *nextPtrPtr;
             ptr != NULL;
             nextPtrPtr = &ptr->nextPtr, ptr = *nextPtrPtr) {
            if (infoPtr == ptr) {
                *nextPtrPtr = ptr->nextPtr;
                break;
            }
          }
      }
    }
}

/*
 *----------------------------------------------------------------------
 *
 * PipeGetHandleProc --
 *
 *    Called from Tcl_GetChannelHandle to retrieve OS handles from
 *    inside a command pipeline based channel.
 *
 * Results:
 *    Returns TCL_OK with the fd in handlePtr, or TCL_ERROR if
 *    there is no handle for the specified direction. 
 *
 * Side effects:
 *    None.
 *
 *----------------------------------------------------------------------
 */

static int
PipeGetHandleProc(instanceData, direction, handlePtr)
    ClientData instanceData;  /* The pipe state. */
    int direction;            /* TCL_READABLE or TCL_WRITABLE */
    ClientData *handlePtr;    /* Where to store the handle.  */
{
    PipeInfo *infoPtr = (PipeInfo *) instanceData;
    WinFile *filePtr; 

    if (direction == TCL_READABLE && infoPtr->readFile) {
      filePtr = (WinFile*) infoPtr->readFile;
      if (filePtr->type == WIN32S_PIPE) {
          if (filePtr->handle == INVALID_HANDLE_VALUE) {
            filePtr->handle = CreateFile(((WinPipe *)filePtr)->fileName,
                  GENERIC_READ, 0, NULL, OPEN_ALWAYS,
                  FILE_ATTRIBUTE_NORMAL, NULL);
          }
          if (filePtr->handle == INVALID_HANDLE_VALUE) {
            return TCL_ERROR;
          }
      }
      *handlePtr = (ClientData) filePtr->handle;
      return TCL_OK;
    }
    if (direction == TCL_WRITABLE && infoPtr->writeFile) {
      filePtr = (WinFile*) infoPtr->writeFile;
      *handlePtr = (ClientData) filePtr->handle;
      return TCL_OK;
    }
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_WaitPid --
 *
 *    Emulates the waitpid system call.
 *
 * Results:
 *    Returns 0 if the process is still alive, -1 on an error, or
 *    the pid on a clean close.  
 *
 * Side effects:
 *    Unless WNOHANG is set and the wait times out, the process
 *    information record will be deleted and the process handle
 *    will be closed.
 *
 *----------------------------------------------------------------------
 */

Tcl_Pid
Tcl_WaitPid(pid, statPtr, options)
    Tcl_Pid pid;
    int *statPtr;
    int options;
{
    ProcInfo *infoPtr, **prevPtrPtr;
    int flags;
    Tcl_Pid result;
    DWORD ret;

    if (!initialized) {
      PipeInit();
    }

    /*
     * If no pid is specified, do nothing.
     */
    
    if (pid == 0) {
      *statPtr = 0;
      return 0;
    }

    /*
     * Find the process on the process list.
     */

    prevPtrPtr = &procList;
    for (infoPtr = procList; infoPtr != NULL;
          prevPtrPtr = &infoPtr->nextPtr, infoPtr = infoPtr->nextPtr) {
       if (infoPtr->hProcess == (HANDLE) pid) {
          break;
      }
    }

    /*
     * If the pid is not one of the processes we know about (we started it)
     * then do nothing.
     */
    
    if (infoPtr == NULL) {
        *statPtr = 0;
      return 0;
    }

    /*
     * Officially "wait" for it to finish. We either poll (WNOHANG) or
     * wait for an infinite amount of time.
     */
    
    if (options & WNOHANG) {
      flags = 0;
    } else {
      flags = INFINITE;
    }
    ret = WaitForSingleObject(infoPtr->hProcess, flags);
    if (ret == WAIT_TIMEOUT) {
      *statPtr = 0;
      if (options & WNOHANG) {
          return 0;
      } else {
          result = 0;
      }
    } else if (ret != WAIT_FAILED) {
      GetExitCodeProcess(infoPtr->hProcess, (DWORD*)statPtr);
      *statPtr = ((*statPtr << 8) & 0xff00);
      result = pid;
    } else {
      errno = ECHILD;
        *statPtr = ECHILD;
      result = (Tcl_Pid) -1;
    }

    /*
     * Remove the process from the process list and close the process handle.
     */

    CloseHandle(infoPtr->hProcess);
    *prevPtrPtr = infoPtr->nextPtr;
    ckfree((char*)infoPtr);

    return result;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PidObjCmd --
 *
 *    This procedure is invoked to process the "pid" Tcl command.
 *    See the user documentation for details on what it does.
 *
 * Results:
 *    A standard Tcl result.
 *
 * Side effects:
 *    See the user documentation.
 *
 *----------------------------------------------------------------------
 */

      /* ARGSUSED */
int
Tcl_PidObjCmd(dummy, interp, objc, objv)
    ClientData dummy;         /* Not used. */
    Tcl_Interp *interp;       /* Current interpreter. */
    int objc;                 /* Number of arguments. */
    Tcl_Obj *CONST *objv;     /* Argument strings. */
{
    Tcl_Channel chan;
    Tcl_ChannelType *chanTypePtr;
    PipeInfo *pipePtr;
    int i;
    Tcl_Obj *resultPtr;
    char buf[20];

    if (objc > 2) {
      Tcl_WrongNumArgs(interp, 1, objv, "?channelId?");
      return TCL_ERROR;
    }
    if (objc == 1) {
      resultPtr = Tcl_GetObjResult(interp);
      sprintf(buf, "%lu", (unsigned long) getpid());
      Tcl_SetStringObj(resultPtr, buf, -1);
    } else {
        chan = Tcl_GetChannel(interp, Tcl_GetStringFromObj(objv[1], NULL),
            NULL);
        if (chan == (Tcl_Channel) NULL) {
          return TCL_ERROR;
      }
      chanTypePtr = Tcl_GetChannelType(chan);
      if (chanTypePtr != &pipeChannelType) {
          return TCL_OK;
      }

        pipePtr = (PipeInfo *) Tcl_GetChannelInstanceData(chan);
      resultPtr = Tcl_GetObjResult(interp);
        for (i = 0; i < pipePtr->numPids; i++) {
          sprintf(buf, "%lu", TclpGetPid(pipePtr->pidPtr[i]));
          Tcl_ListObjAppendElement(/*interp*/ NULL, resultPtr,
                Tcl_NewStringObj(buf, -1));
      }
    }
    return TCL_OK;
}

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