tclpipe.c

linux系统下的音频通信

     * arguments and remove them from the argument list in the pipeline.
     * Count the number of distinct processes (it's the number of "|"
     * arguments plus one) but don't remove the "|" arguments because 
     * they'll be used in the second pass to seperate the individual 
     * child processes.  Cannot start the child processes in this pass 
     * because the redirection symbols may appear anywhere in the 
     * command line -- e.g., the '<' that specifies the input to the 
     * entire pipe may appear at the very end of the argument list.
     */

    lastBar = -1;
    cmdCount = 1;
    for (i = 0; i < argc; i++) {
        skip = 0;
	p = argv[i];
	switch (*p++) {
	case '|':
	    if (*p == '&') {
		p++;
	    }
	    if (*p == '\0') {
		if ((i == (lastBar + 1)) || (i == (argc - 1))) {
		    Tcl_SetResult(interp,
			    "illegal use of | or |& in command",
			    TCL_STATIC);
		    goto error;
		}
	    }
	    lastBar = i;
	    cmdCount++;
	    break;

	case '<':
	    if (inputClose != 0) {
		inputClose = 0;
		TclpCloseFile(inputFile);
	    }
	    if (inputRelease != 0) {
		inputRelease = 0;
		TclpReleaseFile(inputFile);
	    }
	    if (*p == '<') {
		inputFile = NULL;
		inputLiteral = p + 1;
		skip = 1;
		if (*inputLiteral == '\0') {
		    inputLiteral = argv[i + 1];
		    if (inputLiteral == NULL) {
			Tcl_AppendResult(interp, "can't specify \"", argv[i],
				"\" as last word in command", (char *) NULL);
			goto error;
		    }
		    skip = 2;
		}
	    } else {
		inputLiteral = NULL;
		inputFile = FileForRedirect(interp, p, 1, argv[i], 
			argv[i + 1], O_RDONLY, &skip, &inputClose, &inputRelease);
		if (inputFile == NULL) {
		    goto error;
		}
	    }
	    break;

	case '>':
	    atOK = 1;
	    flags = O_WRONLY | O_CREAT | O_TRUNC;
	    errorToOutput = 0;
	    if (*p == '>') {
		p++;
		atOK = 0;
		flags = O_WRONLY | O_CREAT;
	    }
	    if (*p == '&') {
		if (errorClose != 0) {
		    errorClose = 0;
		    TclpCloseFile(errorFile);
		}
		errorToOutput = 1;
		p++;
	    }

	    /*
	     * Close the old output file, but only if the error file is
	     * not also using it.
	     */

	    if (outputClose != 0) {
		outputClose = 0;
		if (errorFile == outputFile) {
		    errorClose = 1;
		} else {
		    TclpCloseFile(outputFile);
		}
	    }
	    if (outputRelease != 0) {
		outputRelease = 0;
		if (errorFile == outputFile) {
		    errorRelease = 1;
		} else {
		    TclpReleaseFile(outputFile);
		}
	    }
	    outputFile = FileForRedirect(interp, p, atOK, argv[i], 
		    argv[i + 1], flags, &skip, &outputClose, &outputRelease);
	    if (outputFile == NULL) {
		goto error;
	    }
	    if (errorToOutput) {
		if (errorClose != 0) {
		    errorClose = 0;
		    TclpCloseFile(errorFile);
		}
		if (errorRelease != 0) {
		    errorRelease = 0;
		    TclpReleaseFile(errorFile);
		}
		errorFile = outputFile;
	    }
	    break;

	case '2':
	    if (*p != '>') {
		break;
	    }
	    p++;
	    atOK = 1;
	    flags = O_WRONLY | O_CREAT | O_TRUNC;
	    if (*p == '>') {
		p++;
		atOK = 0;
		flags = O_WRONLY | O_CREAT;
	    }
	    if (errorClose != 0) {
		errorClose = 0;
		TclpCloseFile(errorFile);
	    }
	    if (errorRelease != 0) {
		errorRelease = 0;
		TclpReleaseFile(errorFile);
	    }
	    errorFile = FileForRedirect(interp, p, atOK, argv[i], 
		    argv[i + 1], flags, &skip, &errorClose, &errorRelease);
	    if (errorFile == NULL) {
		goto error;
	    }
	    break;
	}

	if (skip != 0) {
	    for (j = i + skip; j < argc; j++) {
		argv[j - skip] = argv[j];
	    }
	    argc -= skip;
	    i -= 1;
	}
    }

    if (inputFile == NULL) {
	if (inputLiteral != NULL) {
	    /*
	     * The input for the first process is immediate data coming from
	     * Tcl.  Create a temporary file for it and put the data into the
	     * file.
	     */
	    inputFile = TclpCreateTempFile(inputLiteral, NULL);
	    if (inputFile == NULL) {
		Tcl_AppendResult(interp,
			"couldn't create input file for command: ",
			Tcl_PosixError(interp), (char *) NULL);
		goto error;
	    }
	    inputClose = 1;
	} else if (inPipePtr != NULL) {
	    /*
	     * The input for the first process in the pipeline is to
	     * come from a pipe that can be written from by the caller.
	     */

	    if (TclpCreatePipe(&inputFile, inPipePtr) == 0) {
		Tcl_AppendResult(interp, 
			"couldn't create input pipe for command: ",
			Tcl_PosixError(interp), (char *) NULL);
		goto error;
	    }
	    inputClose = 1;
	} else {
	    /*
	     * The input for the first process comes from stdin.
	     */

	    channel = Tcl_GetStdChannel(TCL_STDIN);
	    if (channel != NULL) {
		inputFile = TclpMakeFile(channel, TCL_READABLE);
		if (inputFile != NULL) {
		    inputRelease = 1;
		}
	    }
	}
    }

    if (outputFile == NULL) {
	if (outPipePtr != NULL) {
	    /*
	     * Output from the last process in the pipeline is to go to a
	     * pipe that can be read by the caller.
	     */

	    if (TclpCreatePipe(outPipePtr, &outputFile) == 0) {
		Tcl_AppendResult(interp, 
			"couldn't create output pipe for command: ",
			Tcl_PosixError(interp), (char *) NULL);
		goto error;
	    }
	    outputClose = 1;
	} else {
	    /*
	     * The output for the last process goes to stdout.
	     */

	    channel = Tcl_GetStdChannel(TCL_STDOUT);
	    if (channel) {
		outputFile = TclpMakeFile(channel, TCL_WRITABLE);
		if (outputFile != NULL) {
		    outputRelease = 1;
		}
	    }
	}
    }

    if (errorFile == NULL) {
	if (errFilePtr != NULL) {
	    /*
	     * Set up the standard error output sink for the pipeline, if
	     * requested.  Use a temporary file which is opened, then deleted.
	     * Could potentially just use pipe, but if it filled up it could
	     * cause the pipeline to deadlock:  we'd be waiting for processes
	     * to complete before reading stderr, and processes couldn't 
	     * complete because stderr was backed up.
	     */

	    errorFile = TclpCreateTempFile(NULL, NULL);
	    if (errorFile == NULL) {
		Tcl_AppendResult(interp,
			"couldn't create error file for command: ",
			Tcl_PosixError(interp), (char *) NULL);
		goto error;
	    }
	    *errFilePtr = errorFile;
	} else {
	    /*
	     * Errors from the pipeline go to stderr.
	     */

	    channel = Tcl_GetStdChannel(TCL_STDERR);
	    if (channel) {
		errorFile = TclpMakeFile(channel, TCL_WRITABLE);
		if (errorFile != NULL) {
		    errorRelease = 1;
		}
	    }
	}
    }
	
    /*
     * Scan through the argc array, creating a process for each
     * group of arguments between the "|" characters.
     */

    Tcl_ReapDetachedProcs();
    pidPtr = (Tcl_Pid *) ckalloc((unsigned) (cmdCount * sizeof(Tcl_Pid)));

    curInFile = inputFile;

    for (i = 0; i < argc; i = lastArg + 1) { 
	int joinThisError;
	Tcl_Pid pid;

	/*
	 * Convert the program name into native form. 
	 */

	argv[i] = Tcl_TranslateFileName(interp, argv[i], &execBuffer);
	if (argv[i] == NULL) {
	    goto error;
	}

	/*
	 * Find the end of the current segment of the pipeline.
	 */

	joinThisError = 0;
	for (lastArg = i; lastArg < argc; lastArg++) {
	    if (argv[lastArg][0] == '|') { 
		if (argv[lastArg][1] == '\0') { 
		    break;
		}
		if ((argv[lastArg][1] == '&') && (argv[lastArg][2] == '\0')) {
		    joinThisError = 1;
		    break;
		}
	    }
	}
	argv[lastArg] = NULL;

	/*
	 * If this is the last segment, use the specified outputFile.
	 * Otherwise create an intermediate pipe.  pipeIn will become the
	 * curInFile for the next segment of the pipe.
	 */

	if (lastArg == argc) { 
	    curOutFile = outputFile;
	} else {
	    if (TclpCreatePipe(&pipeIn, &curOutFile) == 0) {
		Tcl_AppendResult(interp, "couldn't create pipe: ",
			Tcl_PosixError(interp), (char *) NULL);
		goto error;
	    }
	}

	if (joinThisError != 0) {
	    curErrFile = curOutFile;
	} else {
	    curErrFile = errorFile;
	}

	if (TclpCreateProcess(interp, lastArg - i, argv + i,
		curInFile, curOutFile, curErrFile, &pid) != TCL_OK) {
	    goto error;
	}
	Tcl_DStringFree(&execBuffer);

	pidPtr[numPids] = pid;
	numPids++;

	/*
	 * Close off our copies of file descriptors that were set up for
	 * this child, then set up the input for the next child.
	 */

	if ((curInFile != NULL) && (curInFile != inputFile)) {
	    TclpCloseFile(curInFile);
	}
	curInFile = pipeIn;
	pipeIn = NULL;

	if ((curOutFile != NULL) && (curOutFile != outputFile)) {
	    TclpCloseFile(curOutFile);
	}
	curOutFile = NULL;
    }

    *pidArrayPtr = pidPtr;

    /*
     * All done.  Cleanup open files lying around and then return.
     */

cleanup:
    Tcl_DStringFree(&execBuffer);

    if (inputClose) {
	TclpCloseFile(inputFile);
    } else if (inputRelease) {
	TclpReleaseFile(inputFile);
    }
    if (outputClose) {
	TclpCloseFile(outputFile);
    } else if (outputRelease) {
	TclpReleaseFile(outputFile);
    }
    if (errorClose) {
	TclpCloseFile(errorFile);
    } else if (errorRelease) {
	TclpReleaseFile(errorFile);
    }
    return numPids;

    /*
     * An error occurred.  There could have been extra files open, such
     * as pipes between children.  Clean them all up.  Detach any child
     * processes that have been created.
     */

error:
    if (pipeIn != NULL) {
	TclpCloseFile(pipeIn);
    }
    if ((curOutFile != NULL) && (curOutFile != outputFile)) {
	TclpCloseFile(curOutFile);
    }
    if ((curInFile != NULL) && (curInFile != inputFile)) {
	TclpCloseFile(curInFile);
    }
    if ((inPipePtr != NULL) && (*inPipePtr != NULL)) {
	TclpCloseFile(*inPipePtr);
	*inPipePtr = NULL;
    }
    if ((outPipePtr != NULL) && (*outPipePtr != NULL)) {
	TclpCloseFile(*outPipePtr);
	*outPipePtr = NULL;
    }
    if ((errFilePtr != NULL) && (*errFilePtr != NULL)) {
	TclpCloseFile(*errFilePtr);
	*errFilePtr = NULL;
    }
    if (pidPtr != NULL) {
	for (i = 0; i < numPids; i++) {
	    if (pidPtr[i] != (Tcl_Pid) -1) {
		Tcl_DetachPids(1, &pidPtr[i]);
	    }
	}
	ckfree((char *) pidPtr);
    }
    numPids = -1;
    goto cleanup;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_OpenCommandChannel --
 *
 *	Opens an I/O channel to one or more subprocesses specified
 *	by argc and argv.  The flags argument determines the
 *	disposition of the stdio handles.  If the TCL_STDIN flag is
 *	set then the standard input for the first subprocess will
 *	be tied to the channel:  writing to the channel will provide
 *	input to the subprocess.  If TCL_STDIN is not set, then
 *	standard input for the first subprocess will be the same as
 *	this application's standard input.  If TCL_STDOUT is set then
 *	standard output from the last subprocess can be read from the
 *	channel;  otherwise it goes to this application's standard
 *	output.  If TCL_STDERR is set, standard error output for all
 *	subprocesses is returned to the channel and results in an error
 *	when the channel is closed;  otherwise it goes to this
 *	application's standard error.  If TCL_ENFORCE_MODE is not set,
 *	then argc and argv can redirect the stdio handles to override
 *	TCL_STDIN, TCL_STDOUT, and TCL_STDERR;  if it is set, then it 
 *	is an error for argc and argv to override stdio channels for
 *	which TCL_STDIN, TCL_STDOUT, and TCL_STDERR have been set.
 *
 * Results:
 *	A new command channel, or NULL on failure with an error
 *	message left in interp.
 *
 * Side effects:
 *	Creates processes, opens pipes.
 *
 *----------------------------------------------------------------------
 */

Tcl_Channel
Tcl_OpenCommandChannel(interp, argc, argv, flags)
    Tcl_Interp *interp;		/* Interpreter for error reporting. Can
                                 * NOT be NULL. */
    int argc;			/* How many arguments. */
    char **argv;		/* Array of arguments for command pipe. */
    int flags;			/* Or'ed combination of TCL_STDIN, TCL_STDOUT,
				 * TCL_STDERR, and TCL_ENFORCE_MODE. */
{
    TclFile *inPipePtr, *outPipePtr, *errFilePtr;
    TclFile inPipe, outPipe, errFile;
    int numPids;
    Tcl_Pid *pidPtr;
    Tcl_Channel channel;

    inPipe = outPipe = errFile = NULL;

    inPipePtr = (flags & TCL_STDIN) ? &inPipe : NULL;
    outPipePtr = (flags & TCL_STDOUT) ? &outPipe : NULL;
    errFilePtr = (flags & TCL_STDERR) ? &errFile : NULL;
    
    numPids = TclCreatePipeline(interp, argc, argv, &pidPtr, inPipePtr,
            outPipePtr, errFilePtr);

    if (numPids < 0) {
	goto error;
    }

    /*
     * Verify that the pipes that were created satisfy the
     * readable/writable constraints. 
     */

    if (flags & TCL_ENFORCE_MODE) {
	if ((flags & TCL_STDOUT) && (outPipe == NULL)) {
	    Tcl_AppendResult(interp, "can't read output from command:",
		    " standard output was redirected", (char *) NULL);
	    goto error;
	}
	if ((flags & TCL_STDIN) && (inPipe == NULL)) {
	    Tcl_AppendResult(interp, "can't write input to command:",
		    " standard input was redirected", (char *) NULL);
	    goto error;
	}
    }
    
    channel = TclpCreateCommandChannel(outPipe, inPipe, errFile,
	    numPids, pidPtr);

    if (channel == (Tcl_Channel) NULL) {
        Tcl_AppendResult(interp, "pipe for command could not be created",
                (char *) NULL);
	goto error;
    }
    return channel;

error:
    if (numPids > 0) {
	Tcl_DetachPids(numPids, pidPtr);
	ckfree((char *) pidPtr);
    }
    if (inPipe != NULL) {
	TclpCloseFile(inPipe);
    }
    if (outPipe != NULL) {
	TclpCloseFile(outPipe);
    }
    if (errFile != NULL) {
	TclpCloseFile(errFile);
    }
    return NULL;
}