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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) 1994-1998 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 1.1.2.5 1998/12/12 01:36:56 lfb 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 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. */
{
char *p, *p2;
Tcl_DString nameString, valueString;
int i;
/*
* 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);
Tcl_MutexLock(&envMutex);
for (i = 0; ; i++) {
p = environ[i];
if (p == NULL) {
break;
}
p2 = strchr(p, '=');
if (p2 == NULL) {
/*
* 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.
*/
continue;
}
Tcl_ExternalToUtfDString(NULL, p, p2 - p, &nameString);
Tcl_ExternalToUtfDString(NULL, p2 + 1, -1, &valueString);
Tcl_SetVar2(interp, "env", Tcl_DStringValue(&nameString),
Tcl_DStringValue(&valueString), TCL_GLOBAL_ONLY);
Tcl_DStringFree(&nameString);
Tcl_DStringFree(&valueString);
}
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; /* Nname of variable whose value is to be
* set (native). */
CONST char *value; /* New value for variable (native). */
{
int index, length, nameLength;
char *p, *oldValue;
/*
* 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 = 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) {
Tcl_MutexUnlock(&envMutex);
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);
index = FindVariable(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 (environ[index] != p) {
ckfree(p);
} else {
ReplaceString(oldValue, p);
}
Tcl_MutexUnlock(&envMutex);
}
/*
*----------------------------------------------------------------------
*
* 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. (native) */
{
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 (native). */
{
char *oldValue;
int length, index;
#ifdef USE_PUTENV
char *string;
#else
char **envPtr;
#endif
Tcl_MutexLock(&envMutex);
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) {
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
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);
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.
*
*----------------------------------------------------------------------
*/
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;
Tcl_DString nameString;
char *result;
Tcl_MutexLock(&envMutex);
Tcl_UtfToExternalDString(NULL, name, -1, &nameString);
index = FindVariable(Tcl_DStringValue(&nameString), &length);
Tcl_DStringFree(&nameString);
result = NULL;
if ((index != -1) && (*(environ[index]+length) == '=')) {
result = Tcl_ExternalToUtfDString(NULL, environ[index]+length+1,
-1, valuePtr);
}
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. */
char *name1; /* Better be "env". */
char *name2; /* Name of variable being modified, or NULL
* if whole array is being deleted (UTF-8). */
int flags; /* Indicates what's happening. */
{
/*
* If a value is being set, call TclSetEnv to do all of the work.
*/
if (flags & TCL_TRACE_WRITES) {
Tcl_DString nameString, valueString;
char *value;
value = Tcl_GetVar2(interp, "env", name2, TCL_GLOBAL_ONLY);
Tcl_UtfToExternalDString(NULL, name2, -1, &nameString);
Tcl_UtfToExternalDString(NULL, value, -1, &valueString);
TclSetEnv(Tcl_DStringValue(&nameString),
Tcl_DStringValue(&valueString));
Tcl_DStringFree(&nameString);
Tcl_DStringFree(&valueString);
}
/*
* If a value is being read, call TclGetEnv to do all of the work.
*/
if (flags & TCL_TRACE_READS) {
Tcl_DString valueString;
char *value;
value = TclGetEnv(name2, &valueString);
if (value == NULL) {
return "no such variable";
}
Tcl_SetVar2(interp, name1, name2, value, 0);
Tcl_DStringFree(&valueString);
}
/*
* For array traces, let TclSetupEnv do all the work.
*/
if (flags & TCL_TRACE_ARRAY) {
TclSetupEnv(interp);
}
/*
* For unset traces, let TclUnsetEnv do all the work.
*/
if ((flags & TCL_TRACE_UNSETS) && (name2 != NULL)) {
Tcl_DString nameString;
Tcl_UtfToExternalDString(NULL, name2, -1, &nameString);
TclUnsetEnv(Tcl_DStringValue(&nameString));
Tcl_DStringFree(&nameString);
}
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] = (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
* (native). */
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
* unlikely, so we don't bother.
*/
if (environCache) {
ckfree((char *) environCache);
environCache = NULL;
cacheSize = 0;
#ifndef USE_PUTENV
environSize = 0;
#endif
}
}
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