tclmain.c

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/* 
 * tclMain.c --
 *
 *	Main program for Tcl shells and other Tcl-based applications.
 *
 * Copyright (c) 1988-1994 The Regents of the University of California.
 * Copyright (c) 1994-1997 Sun Microsystems, Inc.
 * Copyright (c) 2000 Ajuba Solutions.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * RCS: @(#) $Id: tclMain.c,v 1.20 2002/05/29 22:59:33 dgp Exp $
 */

#include "tcl.h"
#include "tclInt.h"

# undef TCL_STORAGE_CLASS
# define TCL_STORAGE_CLASS DLLEXPORT

/*
 * Declarations for various library procedures and variables (don't want
 * to include tclPort.h here, because people might copy this file out of
 * the Tcl source directory to make their own modified versions).
 */

#if !defined(MAC_TCL)
extern int		isatty _ANSI_ARGS_((int fd));
#else
#include <unistd.h>
#endif

static Tcl_Obj *tclStartupScriptPath = NULL;

static Tcl_MainLoopProc *mainLoopProc = NULL;

/* 
 * Structure definition for information used to keep the state of
 * an interactive command processor that reads lines from standard
 * input and writes prompts and results to standard output.
 */

typedef enum {
    PROMPT_NONE,	/* Print no prompt */
    PROMPT_START,	/* Print prompt for command start */
    PROMPT_CONTINUE	/* Print prompt for command continuation */
} PromptType;

typedef struct InteractiveState {
    Tcl_Channel input;		/* The standard input channel from which
				 * lines are read. */
    int tty;                    /* Non-zero means standard input is a 
				 * terminal-like device.  Zero means it's
				 * a file. */
    Tcl_Obj *commandPtr;	/* Used to assemble lines of input into
				 * Tcl commands. */
    PromptType prompt;		/* Next prompt to print */
    Tcl_Interp *interp;		/* Interpreter that evaluates interactive
				 * commands. */
} InteractiveState;

/*
 * Forward declarations for procedures defined later in this file.
 */

static void		Prompt _ANSI_ARGS_((Tcl_Interp *interp,
			    PromptType *promptPtr));
static void		StdinProc _ANSI_ARGS_((ClientData clientData,
			    int mask));


/*
 *----------------------------------------------------------------------
 *
 * TclSetStartupScriptPath --
 *
 *	Primes the startup script VFS path, used to override the
 *      command line processing.
 *
 * Results:
 *	None. 
 *
 * Side effects:
 *	This procedure initializes the VFS path of the Tcl script to
 *      run at startup.
 *
 *----------------------------------------------------------------------
 */
void TclSetStartupScriptPath(pathPtr)
    Tcl_Obj *pathPtr;
{
    if (tclStartupScriptPath != NULL) {
	Tcl_DecrRefCount(tclStartupScriptPath);
    }
    tclStartupScriptPath = pathPtr;
    if (tclStartupScriptPath != NULL) {
	Tcl_IncrRefCount(tclStartupScriptPath);
    }
}


/*
 *----------------------------------------------------------------------
 *
 * TclGetStartupScriptPath --
 *
 *	Gets the startup script VFS path, used to override the
 *      command line processing.
 *
 * Results:
 *	The startup script VFS path, NULL if none has been set.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */
Tcl_Obj *TclGetStartupScriptPath()
{
    return tclStartupScriptPath;
}


/*
 *----------------------------------------------------------------------
 *
 * TclSetStartupScriptFileName --
 *
 *	Primes the startup script file name, used to override the
 *      command line processing.
 *
 * Results:
 *	None. 
 *
 * Side effects:
 *	This procedure initializes the file name of the Tcl script to
 *      run at startup.
 *
 *----------------------------------------------------------------------
 */
void TclSetStartupScriptFileName(fileName)
    CONST char *fileName;
{
    Tcl_Obj *pathPtr = Tcl_NewStringObj(fileName,-1);
    TclSetStartupScriptPath(pathPtr);
}


/*
 *----------------------------------------------------------------------
 *
 * TclGetStartupScriptFileName --
 *
 *	Gets the startup script file name, used to override the
 *      command line processing.
 *
 * Results:
 *	The startup script file name, NULL if none has been set.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */
CONST char *TclGetStartupScriptFileName()
{
    Tcl_Obj *pathPtr = TclGetStartupScriptPath();

    if (pathPtr == NULL) {
	return NULL;
    }
    return Tcl_GetString(pathPtr);
}



/*
 *----------------------------------------------------------------------
 *
 * Tcl_Main --
 *
 *	Main program for tclsh and most other Tcl-based applications.
 *
 * Results:
 *	None. This procedure never returns (it exits the process when
 *	it's done).
 *
 * Side effects:
 *	This procedure initializes the Tcl world and then starts
 *	interpreting commands;  almost anything could happen, depending
 *	on the script being interpreted.
 *
 *----------------------------------------------------------------------
 */

void
Tcl_Main(argc, argv, appInitProc)
    int argc;			/* Number of arguments. */
    char **argv;		/* Array of argument strings. */
    Tcl_AppInitProc *appInitProc;
				/* Application-specific initialization
				 * procedure to call after most
				 * initialization but before starting to
				 * execute commands. */
{
    Tcl_Obj *resultPtr;
    Tcl_Obj *commandPtr = NULL;
    char buffer[TCL_INTEGER_SPACE + 5], *args;
    PromptType prompt = PROMPT_START;
    int code, length, tty;
    int exitCode = 0;
    Tcl_Channel inChannel, outChannel, errChannel;
    Tcl_Interp *interp;
    Tcl_DString argString;

    Tcl_FindExecutable(argv[0]);

    interp = Tcl_CreateInterp();
    Tcl_InitMemory(interp);

    /*
     * Make command-line arguments available in the Tcl variables "argc"
     * and "argv".  If the first argument doesn't start with a "-" then
     * strip it off and use it as the name of a script file to process.
     */

    if (TclGetStartupScriptPath() == NULL) {
	if ((argc > 1) && (argv[1][0] != '-')) {
	    TclSetStartupScriptFileName(argv[1]);
	    argc--;
	    argv++;
	}
    }

    /*
     * The CONST casting is safe, and better we do it here than force
     * all callers of Tcl_Main to do it.  (Those callers are likely
     * in a main() that can't easily change its signature.)
     */
    
    args = Tcl_Merge(argc-1, (CONST char **)argv+1);
    Tcl_ExternalToUtfDString(NULL, args, -1, &argString);
    Tcl_SetVar(interp, "argv", Tcl_DStringValue(&argString), TCL_GLOBAL_ONLY);
    Tcl_DStringFree(&argString);
    ckfree(args);

    if (TclGetStartupScriptPath() == NULL) {
	Tcl_ExternalToUtfDString(NULL, argv[0], -1, &argString);
    } else {
	TclSetStartupScriptFileName(Tcl_ExternalToUtfDString(NULL,
		TclGetStartupScriptFileName(), -1, &argString));
    }

    TclFormatInt(buffer, (long) argc-1);
    Tcl_SetVar(interp, "argc", buffer, TCL_GLOBAL_ONLY);
    Tcl_SetVar(interp, "argv0", Tcl_DStringValue(&argString), TCL_GLOBAL_ONLY);

    /*
     * Set the "tcl_interactive" variable.
     */

    tty = isatty(0);
    Tcl_SetVar(interp, "tcl_interactive",
	    ((TclGetStartupScriptPath() == NULL) && tty) ? "1" : "0",
	    TCL_GLOBAL_ONLY);
    
    /*
     * Invoke application-specific initialization.
     */

    Tcl_Preserve((ClientData) interp);
    if ((*appInitProc)(interp) != TCL_OK) {
	errChannel = Tcl_GetStdChannel(TCL_STDERR);
	if (errChannel) {
	    Tcl_WriteChars(errChannel,
		    "application-specific initialization failed: ", -1);
	    Tcl_WriteObj(errChannel, Tcl_GetObjResult(interp));
	    Tcl_WriteChars(errChannel, "\n", 1);
	}
    }
    if (Tcl_InterpDeleted(interp)) {
	goto done;
    }

    /*
     * If a script file was specified then just source that file
     * and quit.
     */

    if (TclGetStartupScriptPath() != NULL) {
	code = Tcl_FSEvalFile(interp, TclGetStartupScriptPath());
	if (code != TCL_OK) {
	    errChannel = Tcl_GetStdChannel(TCL_STDERR);
	    if (errChannel) {

		/*
		 * The following statement guarantees that the errorInfo
		 * variable is set properly.
		 */

		Tcl_AddErrorInfo(interp, "");
		Tcl_WriteObj(errChannel, Tcl_GetVar2Ex(interp, "errorInfo",
			NULL, TCL_GLOBAL_ONLY));
		Tcl_WriteChars(errChannel, "\n", 1);
	    }
	    exitCode = 1;
	}
	goto done;
    }
    Tcl_DStringFree(&argString);

    /*
     * We're running interactively.  Source a user-specific startup
     * file if the application specified one and if the file exists.
     */

    Tcl_SourceRCFile(interp);

    /*
     * Process commands from stdin until there's an end-of-file.  Note
     * that we need to fetch the standard channels again after every
     * eval, since they may have been changed.
     */

    commandPtr = Tcl_NewObj();
    Tcl_IncrRefCount(commandPtr);

    /*
     * Get a new value for tty if anyone writes to ::tcl_interactive
     */
    Tcl_LinkVar(interp, "tcl_interactive", (char *) &tty, TCL_LINK_BOOLEAN);
    inChannel = Tcl_GetStdChannel(TCL_STDIN);
    outChannel = Tcl_GetStdChannel(TCL_STDOUT);
    while ((inChannel != (Tcl_Channel) NULL) && !Tcl_InterpDeleted(interp)) {
	if (tty) {
	    Prompt(interp, &prompt);
	    if (Tcl_InterpDeleted(interp)) {
		break;
	    }
	    inChannel = Tcl_GetStdChannel(TCL_STDIN);
	    if (inChannel == (Tcl_Channel) NULL) {
	        break;
	    }
	}
	if (Tcl_IsShared(commandPtr)) {
	    Tcl_DecrRefCount(commandPtr);
	    commandPtr = Tcl_DuplicateObj(commandPtr);
	    Tcl_IncrRefCount(commandPtr);
	}
        length = Tcl_GetsObj(inChannel, commandPtr);
	if (length < 0) {
	    if (Tcl_InputBlocked(inChannel)) {

		/*
		 * This can only happen if stdin has been set to
		 * non-blocking.  In that case cycle back and try
		 * again.  This sets up a tight polling loop (since
		 * we have no event loop running).  If this causes
		 * bad CPU hogging, we might try toggling the blocking
		 * on stdin instead.
		 */