/* * 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: * 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 } }