tclunixpipe.c

tcl是工具命令语言

    }

    /*
     * We need to allocate and convert this before the fork
     * so it is properly deallocated later
     */
    dsArray = (Tcl_DString *) ckalloc(argc * sizeof(Tcl_DString));
    newArgv = (char **) ckalloc((argc+1) * sizeof(char *));
    newArgv[argc] = NULL;
    for (i = 0; i < argc; i++) {
	newArgv[i] = Tcl_UtfToExternalDString(NULL, argv[i], -1, &dsArray[i]);
    }

    joinThisError = errorFile && (errorFile == outputFile);
    pid = fork();
    if (pid == 0) {
	fd = GetFd(errPipeOut);

	/*
	 * Set up stdio file handles for the child process.
	 */

	if (!SetupStdFile(inputFile, TCL_STDIN)
		|| !SetupStdFile(outputFile, TCL_STDOUT)
		|| (!joinThisError && !SetupStdFile(errorFile, TCL_STDERR))
		|| (joinThisError &&
			((dup2(1,2) == -1) ||
			 (fcntl(2, F_SETFD, 0) != 0)))) {
	    sprintf(errSpace,
		    "%dforked process couldn't set up input/output: ", errno);
	    write(fd, errSpace, (size_t) strlen(errSpace));
	    _exit(1);
	}

	/*
	 * Close the input side of the error pipe.
	 */

	RestoreSignals();
	execvp(newArgv[0], newArgv);			/* INTL: Native. */
	sprintf(errSpace, "%dcouldn't execute \"%.150s\": ", errno, argv[0]);
	write(fd, errSpace, (size_t) strlen(errSpace));
	_exit(1);
    }
    
    /*
     * Free the mem we used for the fork
     */
    for (i = 0; i < argc; i++) {
	Tcl_DStringFree(&dsArray[i]);
    }
    ckfree((char *) dsArray);
    ckfree((char *) newArgv);

    if (pid == -1) {
	Tcl_AppendResult(interp, "couldn't fork child process: ",
		Tcl_PosixError(interp), (char *) NULL);
	goto error;
    }

    /*
     * Read back from the error pipe to see if the child started
     * up OK.  The info in the pipe (if any) consists of a decimal
     * errno value followed by an error message.
     */

    TclpCloseFile(errPipeOut);
    errPipeOut = NULL;

    fd = GetFd(errPipeIn);
    count = read(fd, errSpace, (size_t) (sizeof(errSpace) - 1));
    if (count > 0) {
	char *end;
	errSpace[count] = 0;
	errno = strtol(errSpace, &end, 10);
	Tcl_AppendResult(interp, end, Tcl_PosixError(interp),
		(char *) NULL);
	goto error;
    }
    
    TclpCloseFile(errPipeIn);
    *pidPtr = (Tcl_Pid) pid;
    return TCL_OK;

    error:
    if (pid != -1) {
	/*
	 * Reap the child process now if an error occurred during its
	 * startup.  We don't call this with WNOHANG because that can lead to
	 * defunct processes on an MP system.   We shouldn't have to worry
	 * about hanging here, since this is the error case.  [Bug: 6148]
	 */

	Tcl_WaitPid((Tcl_Pid) pid, &status, 0);
    }
    
    if (errPipeIn) {
	TclpCloseFile(errPipeIn);
    }
    if (errPipeOut) {
	TclpCloseFile(errPipeOut);
    }
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * RestoreSignals --
 *
 *      This procedure is invoked in a forked child process just before
 *      exec-ing a new program to restore all signals to their default
 *      settings.
 *
 * Results:
 *      None.
 *
 * Side effects:
 *      Signal settings get changed.
 *
 *----------------------------------------------------------------------
 */
 
static void
RestoreSignals()
{
#ifdef SIGABRT
    signal(SIGABRT, SIG_DFL);
#endif
#ifdef SIGALRM
    signal(SIGALRM, SIG_DFL);
#endif
#ifdef SIGFPE
    signal(SIGFPE, SIG_DFL);
#endif
#ifdef SIGHUP
    signal(SIGHUP, SIG_DFL);
#endif
#ifdef SIGILL
    signal(SIGILL, SIG_DFL);
#endif
#ifdef SIGINT
    signal(SIGINT, SIG_DFL);
#endif
#ifdef SIGPIPE
    signal(SIGPIPE, SIG_DFL);
#endif
#ifdef SIGQUIT
    signal(SIGQUIT, SIG_DFL);
#endif
#ifdef SIGSEGV
    signal(SIGSEGV, SIG_DFL);
#endif
#ifdef SIGTERM
    signal(SIGTERM, SIG_DFL);
#endif
#ifdef SIGUSR1
    signal(SIGUSR1, SIG_DFL);
#endif
#ifdef SIGUSR2
    signal(SIGUSR2, SIG_DFL);
#endif
#ifdef SIGCHLD
    signal(SIGCHLD, SIG_DFL);
#endif
#ifdef SIGCONT
    signal(SIGCONT, SIG_DFL);
#endif
#ifdef SIGTSTP
    signal(SIGTSTP, SIG_DFL);
#endif
#ifdef SIGTTIN
    signal(SIGTTIN, SIG_DFL);
#endif
#ifdef SIGTTOU
    signal(SIGTTOU, SIG_DFL);
#endif
}

/*
 *----------------------------------------------------------------------
 *
 * SetupStdFile --
 *
 *	Set up stdio file handles for the child process, using the
 *	current standard channels if no other files are specified.
 *	If no standard channel is defined, or if no file is associated
 *	with the channel, then the corresponding standard fd is closed.
 *
 * Results:
 *	Returns 1 on success, or 0 on failure.
 *
 * Side effects:
 *	Replaces stdio fds.
 *
 *----------------------------------------------------------------------
 */

static int
SetupStdFile(file, type)
    TclFile file;		/* File to dup, or NULL. */
    int type;			/* One of TCL_STDIN, TCL_STDOUT, TCL_STDERR */
{
    Tcl_Channel channel;
    int fd;
    int targetFd = 0;		/* Initializations here needed only to */
    int direction = 0;		/* prevent warnings about using uninitialized
				 * variables. */

    switch (type) {
	case TCL_STDIN:
	    targetFd = 0;
	    direction = TCL_READABLE;
	    break;
	case TCL_STDOUT:
	    targetFd = 1;
	    direction = TCL_WRITABLE;
	    break;
	case TCL_STDERR:
	    targetFd = 2;
	    direction = TCL_WRITABLE;
	    break;
    }

    if (!file) {
	channel = Tcl_GetStdChannel(type);
	if (channel) {
	    file = TclpMakeFile(channel, direction);
	}
    }
    if (file) {
	fd = GetFd(file);
	if (fd != targetFd) {
	    if (dup2(fd, targetFd) == -1) {
		return 0;
	    }

            /*
             * Must clear the close-on-exec flag for the target FD, since
             * some systems (e.g. Ultrix) do not clear the CLOEXEC flag on
             * the target FD.
             */
            
            fcntl(targetFd, F_SETFD, 0);
	} else {
	    int result;

	    /*
	     * Since we aren't dup'ing the file, we need to explicitly clear
	     * the close-on-exec flag.
	     */

	    result = fcntl(fd, F_SETFD, 0);
	}
    } else {
	close(targetFd);
    }
    return 1;
}

/*
 *----------------------------------------------------------------------
 *
 * TclpCreateCommandChannel --
 *
 *	This function is called by the generic IO level 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.
                                 * Allocated by the caller, freed when
                                 * the channel is closed or the processes
                                 * are detached (in a background exec). */
{
    char channelName[16 + TCL_INTEGER_SPACE];
    int channelId;
    PipeState *statePtr = (PipeState *) ckalloc((unsigned) sizeof(PipeState));
    int mode;

    statePtr->inFile = readFile;
    statePtr->outFile = writeFile;
    statePtr->errorFile = errorFile;
    statePtr->numPids = numPids;
    statePtr->pidPtr = pidPtr;
    statePtr->isNonBlocking = 0;

    mode = 0;
    if (readFile) {
        mode |= TCL_READABLE;
    }
    if (writeFile) {
        mode |= TCL_WRITABLE;
    }
    
    /*
     * Use one of the fds associated with the channel as the
     * channel id.
     */

    if (readFile) {
	channelId = GetFd(readFile);
    } else if (writeFile) {
	channelId = GetFd(writeFile);
    } else if (errorFile) {
	channelId = GetFd(errorFile);
    } else {
	channelId = 0;
    }

    /*
     * 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);
    statePtr->channel = Tcl_CreateChannel(&pipeChannelType, channelName,
            (ClientData) statePtr, mode);
    return statePtr->channel;
}

/*
 *----------------------------------------------------------------------
 *
 * TclGetAndDetachPids --
 *
 *	This procedure is invoked in the generic implementation of a
 *	background "exec" (An exec when invoked with a terminating "&")
 *	to store a list of the PIDs for processes in a command pipeline
 *	in the interp's result and to detach the processes.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Modifies the interp's result. Detaches processes.
 *
 *----------------------------------------------------------------------
 */

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

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

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

    pipePtr = (PipeState *) Tcl_GetChannelInstanceData(chan);
    for (i = 0; i < pipePtr->numPids; i++) {
        TclFormatInt(buf, (long) 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 --
 *
 *	Helper procedure to set blocking and nonblocking modes on a
 *	pipe based channel. Invoked by generic IO level code.
 *
 * Results:
 *	0 if successful, errno when failed.
 *
 * Side effects:
 *	Sets the device into blocking or non-blocking mode.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
static int
PipeBlockModeProc(instanceData, mode)
    ClientData instanceData;		/* Pipe state. */
    int mode;				/* The mode to set. Can be one of
                                         * TCL_MODE_BLOCKING or
                                         * TCL_MODE_NONBLOCKING. */
{
    PipeState *psPtr = (PipeState *) instanceData;
    int curStatus;
    int fd;

#ifndef	USE_FIONBIO