/* 

  * 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) 1994-1998 Sun Microsystems, Inc.

  * Portions Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiaries. All rights reserved.  

  *

  * 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 1.20.2.3 2006/10/31 22:25:08 das Exp $

  */

 #include "tclInt.h"

 #include "tclPort.h"

 TCL_DECLARE_MUTEX(envMutex)	/* To serialize access to environ */

 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 char **ourEnviron = NULL;/* Cache of the array that we allocate.

 				 * We need to track this in case another

 				 * subsystem swaps around the environ array

 				 * like we do.

 				 */

 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

 /*

  * For MacOS X

  */

 #if defined(__APPLE__) && defined(__DYNAMIC__)

 #include <crt_externs.h>

 __private_extern__ char **environ;

 char **environ = NULL;

 #endif

 /*

  * Declarations for local procedures defined in this file:

  */

 static char *		EnvTraceProc _ANSI_ARGS_((ClientData clientData,

 			    Tcl_Interp *interp, CONST char *name1, 

 			    CONST char *name2, int flags));

 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));

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

 static void		TclCygwinPutenv _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 TclSetupEnv, 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. */

 {

     Tcl_DString envString;

     char *p1, *p2;

     int i;

     /*

      * For MacOS X

      */

 #if defined(__APPLE__) && defined(__DYNAMIC__)

     environ = *_NSGetEnviron();

 #endif

     /*

      * Synchronize the values in the environ array with the contents

      * of the Tcl "env" variable.  To do this:

      *    1) Remove the trace that fires when the "env" var is unset.

      *    2) Unset the "env" variable.

      *    3) If there are no environ variables, create an empty "env"

      *       array.  Otherwise populate the array with current values.

      *    4) Add a trace that synchronizes the "env" array.

      */

     Tcl_UntraceVar2(interp, "env", (char *) NULL,

 	    TCL_GLOBAL_ONLY | TCL_TRACE_WRITES | TCL_TRACE_UNSETS |

 	    TCL_TRACE_READS | TCL_TRACE_ARRAY,  EnvTraceProc,

 	    (ClientData) NULL);

     Tcl_UnsetVar2(interp, "env", (char *) NULL, TCL_GLOBAL_ONLY); 

     if (environ[0] == NULL) {

 	Tcl_Obj *varNamePtr;

 	varNamePtr = Tcl_NewStringObj("env", -1);

 	Tcl_IncrRefCount(varNamePtr);

 	TclArraySet(interp, varNamePtr, NULL);	

 	Tcl_DecrRefCount(varNamePtr);

     } else {

 	Tcl_MutexLock(&envMutex);

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

 	    p1 = Tcl_ExternalToUtfDString(NULL, environ[i], -1, &envString);

 	    p2 = strchr(p1, '=');

 	    if (p2 == NULL) {

 		/*

 		 * This condition seem to happen occasionally under some

 		 * versions of Solaris; ignore the entry.

 		 */

 		continue;

 	    }

 	    p2++;

 	    p2[-1] = '\0';

 	    Tcl_SetVar2(interp, "env", p1, p2, TCL_GLOBAL_ONLY);	

 	    Tcl_DStringFree(&envString);

 	}

 	Tcl_MutexUnlock(&envMutex);

     }

     Tcl_TraceVar2(interp, "env", (char *) NULL,

 	    TCL_GLOBAL_ONLY | TCL_TRACE_WRITES | TCL_TRACE_UNSETS |

 	    TCL_TRACE_READS | TCL_TRACE_ARRAY,  EnvTraceProc,

 	    (ClientData) NULL);

 }

 /*

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

  *

  * 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.

  *

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

  */

 void

 TclSetEnv(name, value)

     CONST char *name;		/* Name of variable whose value is to be

 				 * set (UTF-8). */

     CONST char *value;		/* New value for variable (UTF-8). */

 {

     Tcl_DString envString;

     int index, length, nameLength;

     char *p, *oldValue;

     CONST char *p2;

     /*

      * 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.

      */

     Tcl_MutexLock(&envMutex);

     index = TclpFindVariable(name, &length);

     if (index == -1) {

 #ifndef USE_PUTENV

 	/*

 	 * We need to handle the case where the environment may be changed

 	 * outside our control.  environSize is only valid if the current

 	 * environment is the one we allocated. [Bug 979640]

 	 */

 	if ((ourEnviron != environ) || ((length + 2) > environSize)) {

 	    char **newEnviron;

 	    newEnviron = (char **) ckalloc((unsigned)

 		    ((length + 5) * sizeof(char *)));

 	    memcpy((VOID *) newEnviron, (VOID *) environ,

 		    length*sizeof(char *));

 	    if ((environSize != 0) && (ourEnviron != NULL)) {

 		ckfree((char *) ourEnviron);

 	    }

 	    environ = ourEnviron = newEnviron;

 	    environSize = length + 5;

 #if defined(__APPLE__) && defined(__DYNAMIC__)

 	    {

 	    char ***e = _NSGetEnviron();

 	    *e = environ;

 	    }

 #endif

 	}

 	index = length;

 	environ[index + 1] = NULL;

 #endif

 	oldValue = NULL;

 	nameLength = strlen(name);

     } else {

 	CONST char *env;

 	/*

 	 * 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.

 	 */

 	env = Tcl_ExternalToUtfDString(NULL, environ[index], -1, &envString);

 	if (strcmp(value, (env + length + 1)) == 0) {

 	    Tcl_DStringFree(&envString);

 	    Tcl_MutexUnlock(&envMutex);

 	    return;

 	}

 	Tcl_DStringFree(&envString);

 	oldValue = environ[index];

 	nameLength = length;

     }

     /*

      * Create a new entry.  Build a complete UTF string that contains

      * a "name=value" pattern.  Then convert the string to the native

      * encoding, and set the environ array value.

      */

     p = (char *) ckalloc((unsigned) (nameLength + strlen(value) + 2));

     strcpy(p, name);

     p[nameLength] = '=';

     strcpy(p+nameLength+1, value);

     p2 = Tcl_UtfToExternalDString(NULL, p, -1, &envString);

     /*

      * Copy the native string to heap memory.

      */

     p = (char *) ckrealloc(p, (unsigned) (strlen(p2) + 1));

     strcpy(p, p2);

     Tcl_DStringFree(&envString);

 #ifdef USE_PUTENV

     /*

      * Update the system environment.

      */

     putenv(p);

     index = TclpFindVariable(name, &length);

 #else

     environ[index] = p;

 #endif

     /*

      * Watch out for versions of putenv that copy the string (e.g. VC++).

      * In this case we need to free the string immediately.  Otherwise

      * update the string in the cache.

      */

     if ((index != -1) && (environ[index] == p)) {

 	ReplaceString(oldValue, p);

 #ifdef HAVE_PUTENV_THAT_COPIES

     } else {

 	/* This putenv() copies instead of taking ownership */

 	ckfree(p);

 #endif

     }

     Tcl_MutexUnlock(&envMutex);

     if (!strcmp(name, "HOME")) {

 	/* 

 	 * If the user's home directory has changed, we must invalidate

 	 * the filesystem cache, because '~' expansions will now be

 	 * incorrect.

 	 */

         Tcl_FSMountsChanged(NULL);

     }

 }

 /*

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

  *

  * 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.

  *

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

  */

 EXPORT_C int

 Tcl_PutEnv(string)

     CONST char *string;		/* Info about environment variable in the

 				 * form NAME=value. (native) */

 {

     Tcl_DString nameString;   

     CONST char *name;

     char *value;

     if (string == NULL) {

 	return 0;

     }

     /*

      * First convert the native string to UTF.  Then separate the

      * string into name and value parts, and call TclSetEnv to do

      * all of the real work.

      */

     name = Tcl_ExternalToUtfDString(NULL, string, -1, &nameString);

     value = strchr(name, '=');

     if ((value != NULL) && (value != name)) {

 	value[0] = '\0';

 	TclSetEnv(name, value+1);

     }

     Tcl_DStringFree(&nameString);

     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 (UTF-8). */

 {

     char *oldValue;

     int length;

     int index;

 #ifdef USE_PUTENV_FOR_UNSET

     Tcl_DString envString;

     char *string;

 #else

     char **envPtr;

 #endif

     Tcl_MutexLock(&envMutex);

     index = TclpFindVariable(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) {

 	Tcl_MutexUnlock(&envMutex);

 	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_FOR_UNSET

     /*

      * For those platforms that support putenv to unset, Linux indicates

      * that no = should be included, and Windows requires it.

      */

 #ifdef WIN32

     string = ckalloc((unsigned int) length+2);

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

     string[length] = '=';

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

 #else

     string = ckalloc((unsigned int) length+1);

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

     string[length] = '\0';

 #endif

     Tcl_UtfToExternalDString(NULL, string, -1, &envString);

     string = ckrealloc(string, (unsigned) (Tcl_DStringLength(&envString)+1));

     strcpy(string, Tcl_DStringValue(&envString));

     Tcl_DStringFree(&envString);

     putenv(string);

     /*

      * Watch out for versions of putenv that copy the string (e.g. VC++).

      * In this case we need to free the string immediately.  Otherwise

      * update the string in the cache.

      */

     if (environ[index] == string) {

 	ReplaceString(oldValue, string);

 #ifdef HAVE_PUTENV_THAT_COPIES

     } else {

 	/* This putenv() copies instead of taking ownership */

 	ckfree(string);

 #endif

     }

 #else

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

 	envPtr[-1] = *envPtr;

 	if (*envPtr == NULL) {

 	    break;

 	}

     }

     ReplaceString(oldValue, NULL);

 #endif

     Tcl_MutexUnlock(&envMutex);

 }

 /*

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

  *

  * TclGetEnv --

  *

  *	Retrieve the value of an environment variable.

  *

  * Results:

  *	The result is a pointer to a string specifying the value of the

  *	environment variable, or NULL if that environment variable does

  *	not exist.  Storage for the result string is allocated in valuePtr;

  *	the caller must call Tcl_DStringFree() when the result is no

  *	longer needed.

  *

  * Side effects:

  *	None.

  *

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

  */

 CONST char *

 TclGetEnv(name, valuePtr)

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

 				 * (UTF-8). */

     Tcl_DString *valuePtr;	/* Uninitialized or free DString in which

 				 * the value of the environment variable is

 				 * stored. */

 {

     int length, index;

     CONST char *result;

     Tcl_MutexLock(&envMutex);

     index = TclpFindVariable(name, &length);

     result = NULL;

     if (index != -1) {

 	Tcl_DString envStr;

 	result = Tcl_ExternalToUtfDString(NULL, environ[index], -1, &envStr);

 	result += length;

 	if (*result == '=') {

 	    result++;

 	    Tcl_DStringInit(valuePtr);

 	    Tcl_DStringAppend(valuePtr, result, -1);

 	    result = Tcl_DStringValue(valuePtr);

 	} else {

 	    result = NULL;

 	}

 	Tcl_DStringFree(&envStr);

     }

     Tcl_MutexUnlock(&envMutex);

     return result;

 }

 /*

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

  *

  * EnvTraceProc --

  *

  *	This procedure is invoked whenever an environment variable

  *	is read, modified or deleted.  It propagates the change to the global

  *	"environ" 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. */

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

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

 				 * if whole array is being deleted (UTF-8). */

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

 {

     /*

      * For array traces, let TclSetupEnv do all the work.

      */

     if (flags & TCL_TRACE_ARRAY) {

 	TclSetupEnv(interp);

 	return NULL;

     }

     /*

      * If name2 is NULL, then return and do nothing.

      */

     if (name2 == NULL) {

 	return NULL;

     }

     /*

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

      */

     if (flags & TCL_TRACE_WRITES) {

 	CONST char *value;

 	value = Tcl_GetVar2(interp, "env", name2, TCL_GLOBAL_ONLY);

 	TclSetEnv(name2, value);

     }

     /*

      * If a value is being read, call TclGetEnv to do all of the work.

      */

     if (flags & TCL_TRACE_READS) {

 	Tcl_DString valueString;

 	CONST char *value;

 	value = TclGetEnv(name2, &valueString);

 	if (value == NULL) {

 	    return "no such variable";

 	}

 	Tcl_SetVar2(interp, name1, name2, value, 0);

 	Tcl_DStringFree(&valueString);

     }

     /*

      * For unset traces, let TclUnsetEnv do all the work.

      */

     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((unsigned) 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] = newStr;

 	environCache[cacheSize+1] = NULL;

 	cacheSize += 5;

     }

 }

 /*

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

  *

  * 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

      * unlikely, so we don't bother.

      */

     if (environCache) {

 	ckfree((char *) environCache);

 	environCache = NULL;

 	cacheSize    = 0;

 #ifndef USE_PUTENV

 	environSize  = 0;

 #endif

     }

 }

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

 #include <windows.h>

 /*

  * When using cygwin, when an environment variable changes, we need to synch

  * with both the cygwin environment (in case the application C code calls

  * fork) and the Windows environment (in case the application TCL code calls

  * exec, which calls the Windows CreateProcess function).

  */

 static void

 TclCygwinPutenv(str)

     const char *str;

 {

     char *name, *value;

     /* Get the name and value, so that we can change the environment

        variable for Windows.  */

     name = (char *) alloca (strlen (str) + 1);

     strcpy (name, str);

     for (value = name; *value != '=' && *value != '\0'; ++value)

 	;

     if (*value == '\0') {

 	    /* Can't happen.  */

 	    return;

 	}

     *value = '\0';

     ++value;

     if (*value == '\0') {

 	value = NULL;

     }

     /* Set the cygwin environment variable.  */

 #undef putenv

     if (value == NULL) {

 	unsetenv (name);

     } else {

 	putenv(str);

     }

     /*

      * Before changing the environment variable in Windows, if this is PATH,

      * we need to convert the value back to a Windows style path.

      *

      * FIXME: The calling program may know it is running under windows, and

      * may have set the path to a Windows path, or, worse, appended or

      * prepended a Windows path to PATH.

      */

     if (strcmp (name, "PATH") != 0) {

 	/* If this is Path, eliminate any PATH variable, to prevent any

 	   confusion.  */

 	if (strcmp (name, "Path") == 0) {

 	    SetEnvironmentVariable ("PATH", (char *) NULL);

 	    unsetenv ("PATH");

 	}

 	SetEnvironmentVariable (name, value);

     } else {

 	char *buf;

 	    /* Eliminate any Path variable, to prevent any confusion.  */

 	SetEnvironmentVariable ("Path", (char *) NULL);

 	unsetenv ("Path");

 	if (value == NULL) {

 	    buf = NULL;

 	} else {

 	    int size;

 	    size = cygwin_posix_to_win32_path_list_buf_size (value);

 	    buf = (char *) alloca (size + 1);

 	    cygwin_posix_to_win32_path_list (value, buf);

 	}

 	SetEnvironmentVariable (name, buf);

     }

 }

 #endif /* __CYGWIN__ && __WIN32__ */