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/*

 * 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.

 *

 * RCS: @(#) $Id: tclEnv.c,v 1.1.1.1 2002-01-16 10:25:26 markom Exp $

 */

#include "tclInt.h"

#include "tclPort.h"

/* CYGNUS LOCAL */

#if defined(__CYGWIN__) && defined(__WIN32__)

/* Under cygwin, the environment is imported from the cygwin DLL.  */

extern char ***_imp____cygwin_environ;

#define environ (*_imp____cygwin_environ)

/* We need to use a special putenv function to handle PATH.  */

#ifndef USE_PUTENV

#define USE_PUTENV

#endif

#define putenv TclCygwin32Putenv

#endif

/* END CYGNUS LOCAL */

/*

 * 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));

/* CYGNUS LOCAL */

#if defined (__CYGWIN__) && defined(__WIN32__)

static void             TclCygwin32Putenv _ANSI_ARGS_((CONST char *string));

#endif

/*

 *----------------------------------------------------------------------

 *

 * 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 *)));

            /* CYGNUS LOCAL: Added to avoid an error from Purify,

               although I don't personally see where the error would

               occur--ian.  */

            memset((VOID *) newEnviron, 0, (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.

     */

    /* CYGNUS LOCAL: The original code was bogus.  If we are being

       called because of a trace on the env array, then the call to

       Tcl_SetVar2 would free value.  We avoid that by checking

       whether the value is the same before calling Tcl_SetVar2.

       NOTE: This is not necessary in tcl8.1a2 which handles this in a

       completely different, and better, way.  */

    for (eiPtr= firstInterpPtr; eiPtr != NULL; eiPtr = eiPtr->nextPtr) {

        CONST char *v;

        v = Tcl_GetVar2(eiPtr->interp, "env", (char *) name, TCL_GLOBAL_ONLY);

        if (v == NULL || (v != value && strcmp (v, value) != 0)) {

            (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:

 *      Interpreters are updated, as is environ.

 *

 *----------------------------------------------------------------------

 */

void

TclUnsetEnv(name)

    CONST char *name;                   /* Name of variable to remove. */

{

    EnvInterp *eiPtr;

    char *oldValue;

    int length, index;

#ifdef USE_PUTENV

    char *string;

#else

    char **envPtr;

#endif

#ifdef MAC_TCL

    if (environ == NULL) {

        environSize = TclMacCreateEnv();

    }

#endif

    index = FindVariable(name, &length);

    /*

     * First make sure that the environment variable exists to avoid

     * doing needless work and to avoid recursion on the unset.

     */

    if (index == -1) {

        return;

    }

    /*

     * Remember the old value so we can free it if Tcl created the string.

     */

    oldValue = environ[index];

    /*

     * Update the system environment.  This must be done before we

     * update the interpreters or we will recurse.

     */

#ifdef USE_PUTENV

    string = ckalloc(length+2);

    memcpy((VOID *) string, (VOID *) name, (size_t) length);

    string[length] = '=';

    string[length+1] = '\0';

    putenv(string);

    ckfree(string);

#else

    for (envPtr = environ+index+1; ; envPtr++) {

        envPtr[-1] = *envPtr;

        if (*envPtr == NULL) {

            break;

        }

    }

#endif

    /*

     * Replace the old value in the cache.

     */

    ReplaceString(oldValue, NULL);

    /*

     * Update all of the interpreters.

     */

    for (eiPtr = firstInterpPtr; eiPtr != NULL; eiPtr = eiPtr->nextPtr) {

        (void) Tcl_UnsetVar2(eiPtr->interp, "env", (char *) name,

                TCL_GLOBAL_ONLY);

    }

}

/*

 *----------------------------------------------------------------------

 *

 * TclGetEnv --

 *

 *      Retrieve the value of an environment variable.

 *

 * Results:

 *      Returns a pointer to a static string in the environment,

 *      or NULL if the value was not found.

 *

 * Side effects:

 *      None.

 *

 *----------------------------------------------------------------------

 */

char *

TclGetEnv(name)

    CONST char *name;           /* Name of variable to find. */

{

    int length, index;

#ifdef MAC_TCL

    if (environ == NULL) {

        environSize = TclMacCreateEnv();

    }

#endif

    index = FindVariable(name, &length);

    if ((index != -1) &&  (*(environ[index]+length) == '=')) {

        return environ[index]+length+1;

    } else {

        return NULL;

    }

}

/*

 *----------------------------------------------------------------------

 *

 * EnvTraceProc --

 *

 *      This procedure is invoked whenever an environment variable

 *      is modified or deleted.  It propagates the change to the

 *      "environ" array and to any other interpreters for whom

 *      we're managing an "env" array.

 *

 * Results:

 *      Always returns NULL to indicate success.

 *

 * Side effects:

 *      Environment variable changes get propagated.  If the whole

 *      "env" array is deleted, then we stop managing things for

 *      this interpreter (usually this happens because the whole

 *      interpreter is being deleted).

 *

 *----------------------------------------------------------------------

 */

        /* ARGSUSED */

static char *

EnvTraceProc(clientData, interp, name1, name2, flags)

    ClientData clientData;      /* Not used. */

    Tcl_Interp *interp;         /* Interpreter whose "env" variable is

                                 * being modified. */

    char *name1;                /* Better be "env". */

    char *name2;                /* Name of variable being modified, or

                                 * NULL if whole array is being deleted. */

    int flags;                  /* Indicates what's happening. */

{

    /*

     * First see if the whole "env" variable is being deleted.  If

     * so, just forget about this interpreter.

     */

    if (name2 == NULL) {

        register EnvInterp *eiPtr, *prevPtr;

        if ((flags & (TCL_TRACE_UNSETS|TCL_TRACE_DESTROYED))

                != (TCL_TRACE_UNSETS|TCL_TRACE_DESTROYED)) {

            panic("EnvTraceProc called with confusing arguments");

        }

        eiPtr = firstInterpPtr;

        if (eiPtr->interp == interp) {

            firstInterpPtr = eiPtr->nextPtr;

        } else {

            for (prevPtr = eiPtr, eiPtr = eiPtr->nextPtr; ;

                    prevPtr = eiPtr, eiPtr = eiPtr->nextPtr) {

                if (eiPtr == NULL) {

                    panic("EnvTraceProc couldn't find interpreter");

                }

                if (eiPtr->interp == interp) {

                    prevPtr->nextPtr = eiPtr->nextPtr;

                    break;

                }

            }

        }

        ckfree((char *) eiPtr);

        return NULL;

    }

    /*

     * If a value is being set, call TclSetEnv to do all of the work.

     */

    if (flags & TCL_TRACE_WRITES) {

        TclSetEnv(name2, Tcl_GetVar2(interp, "env", name2, TCL_GLOBAL_ONLY));

    }

    if (flags & TCL_TRACE_UNSETS) {

        TclUnsetEnv(name2);

    }

    return NULL;

}

/*

 *----------------------------------------------------------------------

 *

 * ReplaceString --

 *

 *      Replace one string with another in the environment variable

 *      cache.  The cache keeps track of all of the environment

 *      variables that Tcl has modified so they can be freed later.

 *

 * Results:

 *      None.

 *

 * Side effects:

 *      May free the old string.

 *

 *----------------------------------------------------------------------

 */

static void

ReplaceString(oldStr, newStr)

    CONST char *oldStr;         /* Old environment string. */

    char *newStr;               /* New environment string. */

{

    int i;

    char **newCache;

    /*

     * Check to see if the old value was allocated by Tcl.  If so,

     * it needs to be deallocated to avoid memory leaks.  Note that this

     * algorithm is O(n), not O(1).  This will result in n-squared behavior

     * if lots of environment changes are being made.

     */

    for (i = 0; i < cacheSize; i++) {

        if ((environCache[i] == oldStr) || (environCache[i] == NULL)) {

            break;

        }

    }

    if (i < cacheSize) {

        /*

         * Replace or delete the old value.

         */

        if (environCache[i]) {

            ckfree(environCache[i]);

        }

        if (newStr) {

            environCache[i] = newStr;

        } else {

            for (; i < cacheSize-1; i++) {

                environCache[i] = environCache[i+1];

            }

            environCache[cacheSize-1] = NULL;

        }

    } else {

        int allocatedSize = (cacheSize + 5) * sizeof(char *);

        /*

         * We need to grow the cache in order to hold the new string.

         */

        newCache = (char **) ckalloc((size_t) allocatedSize);

        (VOID *) memset(newCache, (int) 0, (size_t) allocatedSize);

        if (environCache) {

            memcpy((VOID *) newCache, (VOID *) environCache,

                    (size_t) (cacheSize * sizeof(char*)));

            ckfree((char *) environCache);

        }

        environCache = newCache;

        environCache[cacheSize] = (char *) newStr;

        environCache[cacheSize+1] = NULL;

        cacheSize += 5;

    }

}

/*

 *----------------------------------------------------------------------

 *

 * FindVariable --

 *

 *      Locate the entry in environ for a given name.

 *

 * Results:

 *      The return value is the index in environ of an entry with the

 *      name "name", or -1 if there is no such entry.   The integer at

 *      *lengthPtr is filled in with the length of name (if a matching

 *      entry is found) or the length of the environ array (if no matching

 *      entry is found).

 *

 * Side effects:

 *      None.

 *

 *----------------------------------------------------------------------

 */

static int

FindVariable(name, lengthPtr)

    CONST char *name;           /* Name of desired environment variable. */

    int *lengthPtr;             /* Used to return length of name (for

                                 * successful searches) or number of non-NULL

                                 * entries in environ (for unsuccessful

                                 * searches). */

{

    int i;

    register CONST char *p1, *p2;

    for (i = 0, p1 = environ[i]; p1 != NULL; i++, p1 = environ[i]) {

        for (p2 = name; *p2 == *p1; p1++, p2++) {

            /* NULL loop body. */

        }

        if ((*p1 == '=') && (*p2 == '\0')) {

            *lengthPtr = p2-name;

            return i;

        }

    }

    *lengthPtr = i;

    return -1;

}

/*

 *----------------------------------------------------------------------

 *

 * TclFinalizeEnvironment --

 *

 *      This function releases any storage allocated by this module

 *      that isn't still in use by the global environment.  Any

 *      strings that are still in the environment will be leaked.

 *

 * Results:

 *      None.

 *

 * Side effects:

 *      May deallocate storage.

 *

 *----------------------------------------------------------------------

 */

void

TclFinalizeEnvironment()

{

    /*

     * For now we just deallocate the cache array and none of the environment

     * strings.  This may leak more memory that strictly necessary, since some

     * of the strings may no longer be in the environment.  However,

     * determining which ones are ok to delete is n-squared, and is pretty