tclio.c

linux系统下的音频通信

/* 
 * tclIO.c --
 *
 *	This file provides the generic portions (those that are the same on
 *	all platforms and for all channel types) of Tcl's IO facilities.
 *
 * Copyright (c) 1998 Scriptics Corporation
 * Copyright (c) 1995-1997 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS: @(#) tclIO.c 1.3 98/06/27 18:10:15
 */

#include	"tclInt.h"
#include	"tclPort.h"

/*
 * Make sure that both EAGAIN and EWOULDBLOCK are defined. This does not
 * compile on systems where neither is defined. We want both defined so
 * that we can test safely for both. In the code we still have to test for
 * both because there may be systems on which both are defined and have
 * different values.
 */

#if ((!defined(EWOULDBLOCK)) && (defined(EAGAIN)))
#   define EWOULDBLOCK EAGAIN
#endif
#if ((!defined(EAGAIN)) && (defined(EWOULDBLOCK)))
#   define EAGAIN EWOULDBLOCK
#endif
#if ((!defined(EAGAIN)) && (!defined(EWOULDBLOCK)))
    error one of EWOULDBLOCK or EAGAIN must be defined
#endif

/*
 * The following structure encapsulates the state for a background channel
 * copy.  Note that the data buffer for the copy will be appended to this
 * structure.
 */

typedef struct CopyState {
    struct Channel *readPtr;	/* Pointer to input channel. */
    struct Channel *writePtr;	/* Pointer to output channel. */
    int readFlags;		/* Original read channel flags. */
    int writeFlags;		/* Original write channel flags. */
    int toRead;			/* Number of bytes to copy, or -1. */
    int total;			/* Total bytes transferred (written). */
    Tcl_Interp *interp;		/* Interp that started the copy. */
    Tcl_Obj *cmdPtr;		/* Command to be invoked at completion. */
    int bufSize;		/* Size of appended buffer. */
    char buffer[1];		/* Copy buffer, this must be the last
				 * field. */
} CopyState;

/*
 * struct ChannelBuffer:
 *
 * Buffers data being sent to or from a channel.
 */

typedef struct ChannelBuffer {
    int nextAdded;		/* The next position into which a character
                                 * will be put in the buffer. */
    int nextRemoved;		/* Position of next byte to be removed
                                 * from the buffer. */
    int bufSize;		/* How big is the buffer? */
    struct ChannelBuffer *nextPtr;
    				/* Next buffer in chain. */
    char buf[4];		/* Placeholder for real buffer. The real
                                 * buffer occuppies this space + bufSize-4
                                 * bytes. This must be the last field in
                                 * the structure. */
} ChannelBuffer;

#define CHANNELBUFFER_HEADER_SIZE	(sizeof(ChannelBuffer) - 4)

/*
 * The following defines the *default* buffer size for channels.
 */

#define CHANNELBUFFER_DEFAULT_SIZE	(1024 * 4)

/*
 * Structure to record a close callback. One such record exists for
 * each close callback registered for a channel.
 */

typedef struct CloseCallback {
    Tcl_CloseProc *proc;		/* The procedure to call. */
    ClientData clientData;		/* Arbitrary one-word data to pass
                                         * to the callback. */
    struct CloseCallback *nextPtr;	/* For chaining close callbacks. */
} CloseCallback;

/*
 * The following structure describes the information saved from a call to
 * "fileevent". This is used later when the event being waited for to
 * invoke the saved script in the interpreter designed in this record.
 */

typedef struct EventScriptRecord {
    struct Channel *chanPtr;	/* The channel for which this script is
                                 * registered. This is used only when an
                                 * error occurs during evaluation of the
                                 * script, to delete the handler. */
    char *script;		/* Script to invoke. */
    Tcl_Interp *interp;		/* In what interpreter to invoke script? */
    int mask;			/* Events must overlap current mask for the
                                 * stored script to be invoked. */
    struct EventScriptRecord *nextPtr;
    				/* Next in chain of records. */
} EventScriptRecord;

/*
 * struct Channel:
 *
 * One of these structures is allocated for each open channel. It contains data
 * specific to the channel but which belongs to the generic part of the Tcl
 * channel mechanism, and it points at an instance specific (and type
 * specific) * instance data, and at a channel type structure.
 */

typedef struct Channel {
    char *channelName;		/* The name of the channel instance in Tcl
                                 * commands. Storage is owned by the generic IO
                                 * code,  is dynamically allocated. */
    int	flags;			/* ORed combination of the flags defined
                                 * below. */
    Tcl_EolTranslation inputTranslation;
				/* What translation to apply for end of line
                                 * sequences on input? */    
    Tcl_EolTranslation outputTranslation;
    				/* What translation to use for generating
                                 * end of line sequences in output? */
    int inEofChar;		/* If nonzero, use this as a signal of EOF
                                 * on input. */
    int outEofChar;             /* If nonzero, append this to the channel
                                 * when it is closed if it is open for
                                 * writing. */
    int unreportedError;	/* Non-zero if an error report was deferred
                                 * because it happened in the background. The
                                 * value is the POSIX error code. */
    ClientData instanceData;	/* Instance specific data. */
    Tcl_ChannelType *typePtr;	/* Pointer to channel type structure. */
    int refCount;		/* How many interpreters hold references to
                                 * this IO channel? */
    CloseCallback *closeCbPtr;	/* Callbacks registered to be called when the
                                 * channel is closed. */
    ChannelBuffer *curOutPtr;	/* Current output buffer being filled. */
    ChannelBuffer *outQueueHead;/* Points at first buffer in output queue. */
    ChannelBuffer *outQueueTail;/* Points at last buffer in output queue. */

    ChannelBuffer *saveInBufPtr;/* Buffer saved for input queue - eliminates
                                 * need to allocate a new buffer for "gets"
                                 * that crosses buffer boundaries. */
    ChannelBuffer *inQueueHead;	/* Points at first buffer in input queue. */
    ChannelBuffer *inQueueTail;	/* Points at last buffer in input queue. */

    struct ChannelHandler *chPtr;/* List of channel handlers registered
                                  * for this channel. */
    int interestMask;		/* Mask of all events this channel has
                                 * handlers for. */
    struct Channel *nextChanPtr;/* Next in list of channels currently open. */
    EventScriptRecord *scriptRecordPtr;
    				/* Chain of all scripts registered for
                                 * event handlers ("fileevent") on this
                                 * channel. */
    int bufSize;		/* What size buffers to allocate? */
    Tcl_TimerToken timer;	/* Handle to wakeup timer for this channel. */
    CopyState *csPtr;		/* State of background copy, or NULL. */
} Channel;
    
/*
 * Values for the flags field in Channel. Any ORed combination of the
 * following flags can be stored in the field. These flags record various
 * options and state bits about the channel. In addition to the flags below,
 * the channel can also have TCL_READABLE (1<<1) and TCL_WRITABLE (1<<2) set.
 */

#define CHANNEL_NONBLOCKING	(1<<3)	/* Channel is currently in
					 * nonblocking mode. */
#define CHANNEL_LINEBUFFERED	(1<<4)	/* Output to the channel must be
					 * flushed after every newline. */
#define CHANNEL_UNBUFFERED	(1<<5)	/* Output to the channel must always
					 * be flushed immediately. */
#define BUFFER_READY		(1<<6)	/* Current output buffer (the
					 * curOutPtr field in the
                                         * channel structure) should be
                                         * output as soon as possible even
                                         * though it may not be full. */
#define BG_FLUSH_SCHEDULED	(1<<7)	/* A background flush of the
					 * queued output buffers has been
                                         * scheduled. */
#define CHANNEL_CLOSED		(1<<8)	/* Channel has been closed. No
					 * further Tcl-level IO on the
                                         * channel is allowed. */
#define CHANNEL_EOF		(1<<9)	/* EOF occurred on this channel.
					 * This bit is cleared before every
                                         * input operation. */
#define CHANNEL_STICKY_EOF	(1<<10)	/* EOF occurred on this channel because
					 * we saw the input eofChar. This bit
                                         * prevents clearing of the EOF bit
                                         * before every input operation. */
#define CHANNEL_BLOCKED	(1<<11)	/* EWOULDBLOCK or EAGAIN occurred
					 * on this channel. This bit is
                                         * cleared before every input or
                                         * output operation. */
#define INPUT_SAW_CR		(1<<12)	/* Channel is in CRLF eol input
					 * translation mode and the last
                                         * byte seen was a "\r". */
#define CHANNEL_DEAD		(1<<13)	/* The channel has been closed by
					 * the exit handler (on exit) but
                                         * not deallocated. When any IO
                                         * operation sees this flag on a
                                         * channel, it does not call driver
                                         * level functions to avoid referring
                                         * to deallocated data. */
#define CHANNEL_GETS_BLOCKED	(1<<14)	/* The last input operation was a gets
					 * that failed to get a comlete line.
					 * When set, file events will not be
					 * delivered for buffered data unless
					 * an EOL is present. */

/*
 * For each channel handler registered in a call to Tcl_CreateChannelHandler,
 * there is one record of the following type. All of records for a specific
 * channel are chained together in a singly linked list which is stored in
 * the channel structure.
 */

typedef struct ChannelHandler {
    Channel *chanPtr;		/* The channel structure for this channel. */
    int mask;			/* Mask of desired events. */
    Tcl_ChannelProc *proc;	/* Procedure to call in the type of
                                 * Tcl_CreateChannelHandler. */
    ClientData clientData;	/* Argument to pass to procedure. */
    struct ChannelHandler *nextPtr;
    				/* Next one in list of registered handlers. */
} ChannelHandler;

/*
 * This structure keeps track of the current ChannelHandler being invoked in
 * the current invocation of ChannelHandlerEventProc. There is a potential
 * problem if a ChannelHandler is deleted while it is the current one, since
 * ChannelHandlerEventProc needs to look at the nextPtr field. To handle this
 * problem, structures of the type below indicate the next handler to be
 * processed for any (recursively nested) dispatches in progress. The
 * nextHandlerPtr field is updated if the handler being pointed to is deleted.
 * The nextPtr field is used to chain together all recursive invocations, so
 * that Tcl_DeleteChannelHandler can find all the recursively nested
 * invocations of ChannelHandlerEventProc and compare the handler being
 * deleted against the NEXT handler to be invoked in that invocation; when it
 * finds such a situation, Tcl_DeleteChannelHandler updates the nextHandlerPtr
 * field of the structure to the next handler.
 */

typedef struct NextChannelHandler {
    ChannelHandler *nextHandlerPtr;	/* The next handler to be invoked in
                                         * this invocation. */
    struct NextChannelHandler *nestedHandlerPtr;
					/* Next nested invocation of
                                         * ChannelHandlerEventProc. */
} NextChannelHandler;

/*
 * This variable holds the list of nested ChannelHandlerEventProc invocations.
 */

static NextChannelHandler *nestedHandlerPtr = (NextChannelHandler *) NULL;

/*
 * List of all channels currently open.
 */

static Channel *firstChanPtr = (Channel *) NULL;

/*
 * Has a channel exit handler been created yet?
 */

static int channelExitHandlerCreated = 0;

/*
 * The following structure describes the event that is added to the Tcl
 * event queue by the channel handler check procedure.
 */

typedef struct ChannelHandlerEvent {
    Tcl_Event header;		/* Standard header for all events. */
    Channel *chanPtr;		/* The channel that is ready. */
    int readyMask;		/* Events that have occurred. */
} ChannelHandlerEvent;

/*
 * Static variables to hold channels for stdin, stdout and stderr.
 */

static Tcl_Channel stdinChannel = NULL;
static int stdinInitialized = 0;
static Tcl_Channel stdoutChannel = NULL;
static int stdoutInitialized = 0;
static Tcl_Channel stderrChannel = NULL;
static int stderrInitialized = 0;

/*
 * Static functions in this file:
 */

static void		ChannelEventScriptInvoker _ANSI_ARGS_((
			    ClientData clientData, int flags));
static void		ChannelTimerProc _ANSI_ARGS_((
			    ClientData clientData));
static void		CheckForStdChannelsBeingClosed _ANSI_ARGS_((
			    Tcl_Channel chan));
static void		CleanupChannelHandlers _ANSI_ARGS_((
			    Tcl_Interp *interp, Channel *chanPtr));
static int		CloseChannel _ANSI_ARGS_((Tcl_Interp *interp,
                            Channel *chanPtr, int errorCode));
static void		CloseChannelsOnExit _ANSI_ARGS_((ClientData data));
static int		CopyAndTranslateBuffer _ANSI_ARGS_((
			    Channel *chanPtr, char *result, int space));
static int		CopyData _ANSI_ARGS_((CopyState *csPtr, int mask));
static void		CopyEventProc _ANSI_ARGS_((ClientData clientData,
			    int mask));
static void		CreateScriptRecord _ANSI_ARGS_((
			    Tcl_Interp *interp, Channel *chanPtr,
                            int mask, char *script));
static void		DeleteChannelTable _ANSI_ARGS_((
			    ClientData clientData, Tcl_Interp *interp));
static void		DeleteScriptRecord _ANSI_ARGS_((Tcl_Interp *interp,
        		    Channel *chanPtr, int mask));
static void		DiscardInputQueued _ANSI_ARGS_((
			    Channel *chanPtr, int discardSavedBuffers));
static void		DiscardOutputQueued _ANSI_ARGS_((
    			    Channel *chanPtr));
static int		DoRead _ANSI_ARGS_((Channel *chanPtr, char *srcPtr,
			    int slen));
static int		DoWrite _ANSI_ARGS_((Channel *chanPtr, char *srcPtr,
			    int slen));
static int		FlushChannel _ANSI_ARGS_((Tcl_Interp *interp,
                            Channel *chanPtr, int calledFromAsyncFlush));
static Tcl_HashTable	*GetChannelTable _ANSI_ARGS_((Tcl_Interp *interp));
static int		GetEOL _ANSI_ARGS_((Channel *chanPtr));
static int		GetInput _ANSI_ARGS_((Channel *chanPtr));
static void		RecycleBuffer _ANSI_ARGS_((Channel *chanPtr,
		            ChannelBuffer *bufPtr, int mustDiscard));
static int		ScanBufferForEOL _ANSI_ARGS_((Channel *chanPtr,
                            ChannelBuffer *bufPtr,
                            Tcl_EolTranslation translation, int eofChar,
		            int *bytesToEOLPtr, int *crSeenPtr));
static int		ScanInputForEOL _ANSI_ARGS_((Channel *chanPtr,
		            int *bytesQueuedPtr));
static int		SetBlockMode _ANSI_ARGS_((Tcl_Interp *interp,
		            Channel *chanPtr, int mode));
static void		StopCopy _ANSI_ARGS_((CopyState *csPtr));
static void		UpdateInterest _ANSI_ARGS_((Channel *chanPtr));
static int		CheckForDeadChannel _ANSI_ARGS_((Tcl_Interp *interp,
							Channel *chan));

/*
 *----------------------------------------------------------------------
 *
 * SetBlockMode --
 *
 *	This function sets the blocking mode for a channel and updates
 *	the state flags.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	Modifies the blocking mode of the channel and possibly generates
 *	an error.
 *
 *----------------------------------------------------------------------
 */

static int
SetBlockMode(interp, chanPtr, mode)
    Tcl_Interp *interp;		/* Interp for error reporting. */
    Channel *chanPtr;		/* Channel to modify. */
    int mode;			/* One of TCL_MODE_BLOCKING or
				 * TCL_MODE_NONBLOCKING. */
{
    int result = 0;
    if (chanPtr->typePtr->blockModeProc != NULL) {
	result = (chanPtr->typePtr->blockModeProc) (chanPtr->instanceData,
		mode);
    }
    if (result != 0) {
	Tcl_SetErrno(result);
	if (interp != (Tcl_Interp *) NULL) {
	    Tcl_AppendResult(interp, "error setting blocking mode: ",
		    Tcl_PosixError(interp), (char *) NULL);
	}
	return TCL_ERROR;
    }
    if (mode == TCL_MODE_BLOCKING) {
	chanPtr->flags &= (~(CHANNEL_NONBLOCKING | BG_FLUSH_SCHEDULED));
    } else {
	chanPtr->flags |= CHANNEL_NONBLOCKING;
    }
    return TCL_OK;