tclenv.c

linux系统下的音频通信

/* 
 * tclEnv.c --
 *
 *	Tcl support for environment variables, including a setenv
 *	procedure.  This file contains the generic portion of the
 *	environment module.  It is primarily responsible for keeping
 *	the "env" arrays in sync with the system environment variables.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1996 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: @(#) tclEnv.c 1.54 97/10/27 17:47:52
 */

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

/*
 * The structure below is used to keep track of all of the interpereters
 * for which we're managing the "env" array.  It's needed so that they
 * can all be updated whenever an environment variable is changed
 * anywhere.
 */

typedef struct EnvInterp {
    Tcl_Interp *interp;		/* Interpreter for which we're managing
				 * the env array. */
    struct EnvInterp *nextPtr;	/* Next in list of all such interpreters,
				 * or zero. */
} EnvInterp;

static EnvInterp *firstInterpPtr = NULL;
				/* First in list of all managed interpreters,
				 * or NULL if none. */

static int cacheSize = 0;	/* Number of env strings in environCache. */
static char **environCache = NULL;
				/* Array containing all of the environment
				 * strings that Tcl has allocated. */

#ifndef USE_PUTENV
static int environSize = 0;	/* Non-zero means that the environ array was
				 * malloced and has this many total entries
				 * allocated to it (not all may be in use at
				 * once).  Zero means that the environment
				 * array is in its original static state. */
#endif

/*
 * Declarations for local procedures defined in this file:
 */

static char *		EnvTraceProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp, char *name1, char *name2,
			    int flags));
static int		FindVariable _ANSI_ARGS_((CONST char *name,
			    int *lengthPtr));
static void		ReplaceString _ANSI_ARGS_((CONST char *oldStr,
			    char *newStr));
void			TclSetEnv _ANSI_ARGS_((CONST char *name,
			    CONST char *value));
void			TclUnsetEnv _ANSI_ARGS_((CONST char *name));

/*
 *----------------------------------------------------------------------
 *
 * TclSetupEnv --
 *
 *	This procedure is invoked for an interpreter to make environment
 *	variables accessible from that interpreter via the "env"
 *	associative array.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The interpreter is added to a list of interpreters managed
 *	by us, so that its view of envariables can be kept consistent
 *	with the view in other interpreters.  If this is the first
 *	call to Tcl_SetupEnv, then additional initialization happens,
 *	such as copying the environment to dynamically-allocated space
 *	for ease of management.
 *
 *----------------------------------------------------------------------
 */

void
TclSetupEnv(interp)
    Tcl_Interp *interp;		/* Interpreter whose "env" array is to be
				 * managed. */
{
    EnvInterp *eiPtr;
    char *p, *p2;
    Tcl_DString ds;
    int i, sz;

#ifdef MAC_TCL
    if (environ == NULL) {
	environSize = TclMacCreateEnv();
    }
#endif

    /*
     * Next, initialize the DString we are going to use for copying
     * the names of the environment variables.
     */

    Tcl_DStringInit(&ds);
    
    /*
     * Next, add the interpreter to the list of those that we manage.
     */

    eiPtr = (EnvInterp *) ckalloc(sizeof(EnvInterp));
    eiPtr->interp = interp;
    eiPtr->nextPtr = firstInterpPtr;
    firstInterpPtr = eiPtr;

    /*
     * Store the environment variable values into the interpreter's
     * "env" array, and arrange for us to be notified on future
     * writes and unsets to that array.
     */

    (void) Tcl_UnsetVar2(interp, "env", (char *) NULL, TCL_GLOBAL_ONLY);
    for (i = 0; ; i++) {
	p = environ[i];
	if (p == NULL) {
	    break;
	}
	for (p2 = p; *p2 != '='; p2++) {
	    if (*p2 == 0) {
		/*
		 * This condition doesn't seem like it should ever happen,
		 * but it does seem to happen occasionally under some
		 * versions of Solaris; ignore the entry.
		 */

		goto nextEntry;
	    }
	}
        sz = p2 - p;
        Tcl_DStringSetLength(&ds, 0);
        Tcl_DStringAppend(&ds, p, sz);
	(void) Tcl_SetVar2(interp, "env", Tcl_DStringValue(&ds),
                p2+1, TCL_GLOBAL_ONLY);
	nextEntry:
	continue;
    }
    Tcl_TraceVar2(interp, "env", (char *) NULL,
	    TCL_GLOBAL_ONLY | TCL_TRACE_WRITES | TCL_TRACE_UNSETS,
	    EnvTraceProc, (ClientData) NULL);

    /*
     * Finally clean up the DString.
     */

    Tcl_DStringFree(&ds);
}

/*
 *----------------------------------------------------------------------
 *
 * TclSetEnv --
 *
 *	Set an environment variable, replacing an existing value
 *	or creating a new variable if there doesn't exist a variable
 *	by the given name.  This procedure is intended to be a
 *	stand-in for the  UNIX "setenv" procedure so that applications
 *	using that procedure will interface properly to Tcl.  To make
 *	it a stand-in, the Makefile must define "TclSetEnv" to "setenv".
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The environ array gets updated, as do all of the interpreters
 *	that we manage.
 *
 *----------------------------------------------------------------------
 */

void
TclSetEnv(name, value)
    CONST char *name;		/* Name of variable whose value is to be
				 * set. */
    CONST char *value;		/* New value for variable. */
{
    int index, length, nameLength;
    char *p, *oldValue;
    EnvInterp *eiPtr;

#ifdef MAC_TCL
    if (environ == NULL) {
	environSize = TclMacCreateEnv();
    }
#endif

    /*
     * Figure out where the entry is going to go.  If the name doesn't
     * already exist, enlarge the array if necessary to make room.  If
     * the name exists, free its old entry.
     */

    index = FindVariable(name, &length);
    if (index == -1) {
#ifndef USE_PUTENV
	if ((length+2) > environSize) {
	    char **newEnviron;

	    newEnviron = (char **) ckalloc((unsigned)
		    ((length+5) * sizeof(char *)));
	    memcpy((VOID *) newEnviron, (VOID *) environ,
		    length*sizeof(char *));
	    if (environSize != 0) {
		ckfree((char *) environ);
	    }
	    environ = newEnviron;
	    environSize = length+5;
	}
	index = length;
	environ[index+1] = NULL;
#endif
	oldValue = NULL;
	nameLength = strlen(name);
    } else {
	/*
	 * Compare the new value to the existing value.  If they're
	 * the same then quit immediately (e.g. don't rewrite the
	 * value or propagate it to other interpreters).  Otherwise,
	 * when there are N interpreters there will be N! propagations
	 * of the same value among the interpreters.
	 */

	if (strcmp(value, environ[index]+length+1) == 0) {
	    return;
	}
	oldValue = environ[index];
	nameLength = length;
    }
	

    /*
     * Create a new entry.
     */

    p = (char *) ckalloc((unsigned) (nameLength + strlen(value) + 2));
    strcpy(p, name);
    p[nameLength] = '=';
    strcpy(p+nameLength+1, value);

    /*
     * Update the system environment.
     */

#ifdef USE_PUTENV
    putenv(p);
#else
    environ[index] = p;
#endif

    /*
     * Replace the old value with the new value in the cache.
     */

    ReplaceString(oldValue, p);

    /*
     * Update all of the interpreters.
     */

    for (eiPtr= firstInterpPtr; eiPtr != NULL; eiPtr = eiPtr->nextPtr) {
	(void) Tcl_SetVar2(eiPtr->interp, "env", (char *) name,
		(char *) value, TCL_GLOBAL_ONLY);
    }

}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PutEnv --
 *
 *	Set an environment variable.  Similar to setenv except that
 *	the information is passed in a single string of the form
 *	NAME=value, rather than as separate name strings.  This procedure
 *	is intended to be a stand-in for the  UNIX "putenv" procedure
 *	so that applications using that procedure will interface
 *	properly to Tcl.  To make it a stand-in, the Makefile will
 *	define "Tcl_PutEnv" to "putenv".
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	The environ array gets updated, as do all of the interpreters
 *	that we manage.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_PutEnv(string)
    CONST char *string;		/* Info about environment variable in the
				 * form NAME=value. */
{
    int nameLength;
    char *name, *value;

    if (string == NULL) {
	return 0;
    }

    /*
     * Separate the string into name and value parts, then call
     * TclSetEnv to do all of the real work.
     */

    value = strchr(string, '=');
    if (value == NULL) {
	return 0;
    }
    nameLength = value - string;
    if (nameLength == 0) {
	return 0;
    }
    name = (char *) ckalloc((unsigned) nameLength+1);
    memcpy((VOID *) name, (VOID *) string, (size_t) nameLength);
    name[nameLength] = 0;
    TclSetEnv(name, value+1);
    ckfree(name);
    return 0;
}

/*
 *----------------------------------------------------------------------
 *
 * TclUnsetEnv --
 *
 *	Remove an environment variable, updating the "env" arrays
 *	in all interpreters managed by us.  This function is intended
 *	to replace the UNIX "unsetenv" function (but to do this the
 *	Makefile must be modified to redefine "TclUnsetEnv" to
 *	"unsetenv".
 *
 * Results:
 *	None.
 *
 * Side effects: