summaryrefslogtreecommitdiffstats
path: root/generic/tclEnv.c
blob: 4e5854e1eb6a9578c145bfab92df4e5cf093fe71 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
/* 
 * 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 1.4 1999/04/16 00:46:46 stanton 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 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 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;

    /*
     * 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, *p2, *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 = TclpFindVariable(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 {
	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);
    ckfree(p);
    

#ifdef USE_PUTENV
    /*
     * Update the system environment.
     */

    putenv(p2);
    index = TclpFindVariable(name, &length);
#else
    /*
     * Copy the native string to heap memory.
     */
    
    p = (char *) ckalloc((unsigned) (strlen(p2) + 1));
    strcpy(p, p2);
    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) {
	Tcl_DStringFree(&envString);
    } 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) */
{
    Tcl_DString nameString;   
    int nameLength;
    char *name, *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) {
	return 0;
    }
    nameLength = value - name;
    if (nameLength == 0) {
	return 0;
    }

    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, index;
#ifdef USE_PUTENV
    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
    string = ckalloc(length+2);
    memcpy((VOID *) string, (VOID *) name, (size_t) length);
    string[length] = '=';
    string[length+1] = '\0';
    
    Tcl_UtfToExternalDString(NULL, string, -1, &envString);
    ckfree(string);
    string = Tcl_DStringValue(&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) {
	Tcl_DStringFree(&envString);
    } else {
	ReplaceString(oldValue, string);
    }
#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.
 *
 *----------------------------------------------------------------------
 */

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;
    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. */
    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. */
{
    /*
     * 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) {
	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;
	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] = (char *) 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
    }
}