/*
* 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 1.3 1999/02/02 23:01:59 stanton Exp $
*/
#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:
* 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
* unlikely, so we don't bother.
*/
if (environCache) {
ckfree((char *) environCache);
environCache = NULL;
cacheSize = 0;
#ifndef USE_PUTENV
environSize = 0;
#endif
}
}