summaryrefslogtreecommitdiffstats
path: root/generic/tclPkg.c
blob: f92bd18fc89f8d45865090a5b0b7ec31e9493114 (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
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
/*
 * tclPkg.c --
 *
 *	This file implements package and version control for Tcl via the
 *	"package" command and a few C APIs.
 *
 * Copyright (c) 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: tclPkg.c,v 1.14 2005/11/08 18:26:59 dgp Exp $
 */

#include "tclInt.h"

/*
 * Each invocation of the "package ifneeded" command creates a structure of
 * the following type, which is used to load the package into the interpreter
 * if it is requested with a "package require" command.
 */

typedef struct PkgAvail {
    char *version;		/* Version string; malloc'ed. */
    char *script;		/* Script to invoke to provide this version of
				 * the package. Malloc'ed and protected by
				 * Tcl_Preserve and Tcl_Release. */
    struct PkgAvail *nextPtr;	/* Next in list of available versions of the
				 * same package. */
} PkgAvail;

/*
 * For each package that is known in any way to an interpreter, there is one
 * record of the following type. These records are stored in the
 * "packageTable" hash table in the interpreter, keyed by package name such as
 * "Tk" (no version number).
 */

typedef struct Package {
    char *version;		/* Version that has been supplied in this
				 * interpreter via "package provide"
				 * (malloc'ed). NULL means the package
				 * doesn't exist in this interpreter yet. */
    PkgAvail *availPtr;		/* First in list of all available versions of
				 * this package. */
    ClientData clientData;	/* Client data. */
} Package;

/*
 * Prototypes for functions defined in this file:
 */

static int		CheckVersion(Tcl_Interp *interp, CONST char *string);
static int		ComparePkgVersions(CONST char *v1, CONST char *v2,
			    int *satPtr);
static Package *	FindPackage(Tcl_Interp *interp, CONST char *name);

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PkgProvide / Tcl_PkgProvideEx --
 *
 *	This function is invoked to declare that a particular version of a
 *	particular package is now present in an interpreter. There must not be
 *	any other version of this package already provided in the interpreter.
 *
 * Results:
 *	Normally returns TCL_OK; if there is already another version of the
 *	package loaded then TCL_ERROR is returned and an error message is left
 *	in the interp's result.
 *
 * Side effects:
 *	The interpreter remembers that this package is available, so that no
 *	other version of the package may be provided for the interpreter.
 *
 *----------------------------------------------------------------------
 */

int
Tcl_PkgProvide(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of package. */
    CONST char *version)	/* Version string for package. */
{
    return Tcl_PkgProvideEx(interp, name, version, (ClientData) NULL);
}

int
Tcl_PkgProvideEx(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of package. */
    CONST char *version,	/* Version string for package. */
    ClientData clientData)	/* clientdata for this package (normally used
				 * for C callback function table) */
{
    Package *pkgPtr;

    pkgPtr = FindPackage(interp, name);
    if (pkgPtr->version == NULL) {
	pkgPtr->version = ckalloc((unsigned) (strlen(version) + 1));
	strcpy(pkgPtr->version, version);
	pkgPtr->clientData = clientData;
	return TCL_OK;
    }
    if (ComparePkgVersions(pkgPtr->version, version, NULL) == 0) {
	if (clientData != NULL) {
	    pkgPtr->clientData = clientData;
	}
	return TCL_OK;
    }
    Tcl_AppendResult(interp, "conflicting versions provided for package \"",
	    name, "\": ", pkgPtr->version, ", then ", version, NULL);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PkgRequire / Tcl_PkgRequireEx --
 *
 *	This function is called by code that depends on a particular version
 *	of a particular package. If the package is not already provided in the
 *	interpreter, this function invokes a Tcl script to provide it. If the
 *	package is already provided, this function makes sure that the
 *	caller's needs don't conflict with the version that is present.
 *
 * Results:
 *	If successful, returns the version string for the currently provided
 *	version of the package, which may be different from the "version"
 *	argument. If the caller's requirements cannot be met (e.g. the version
 *	requested conflicts with a currently provided version, or the required
 *	version cannot be found, or the script to provide the required version
 *	generates an error), NULL is returned and an error message is left in
 *	the interp's result.
 *
 * Side effects:
 *	The script from some previous "package ifneeded" command may be
 *	invoked to provide the package.
 *
 *----------------------------------------------------------------------
 */

CONST char *
Tcl_PkgRequire(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of desired package. */
    CONST char *version,	/* Version string for desired version; NULL
				 * means use the latest version available. */
    int exact)			/* Non-zero means that only the particular
				 * version given is acceptable. Zero means use
				 * the latest compatible version. */
{
    return Tcl_PkgRequireEx(interp, name, version, exact, NULL);
}

CONST char *
Tcl_PkgRequireEx(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of desired package. */
    CONST char *version,	/* Version string for desired version; NULL
				 * means use the latest version available. */
    int exact,			/* Non-zero means that only the particular
				 * version given is acceptable. Zero means use
				 * the latest compatible version. */
    ClientData *clientDataPtr)	/* Used to return the client data for this
				 * package. If it is NULL then the client data
				 * is not returned. This is unchanged if this
				 * call fails for any reason. */
{
    Package *pkgPtr;
    PkgAvail *availPtr, *bestPtr;
    char *script;
    int code, satisfies, result, pass;
    Tcl_DString command;

    /*
     * If an attempt is being made to load this into a standalone executable
     * on a platform where backlinking is not supported then this must be a
     * shared version of Tcl (Otherwise the load would have failed). Detect
     * this situation by checking that this library has been correctly
     * initialised. If it has not been then return immediately as nothing will
     * work.
     */

    if (tclEmptyStringRep == NULL) {
	/*
	 * OK, so what's going on here?
	 *
	 * First, what are we doing? We are performing a check on behalf of
	 * one particular caller, Tcl_InitStubs(). When a package is stub-
	 * enabled, it is statically linked to libtclstub.a, which contains a
	 * copy of Tcl_InitStubs(). When a stub-enabled package is loaded, its
	 * *_Init() function is supposed to call Tcl_InitStubs() before
	 * calling any other functions in the Tcl library. The first Tcl
	 * function called by Tcl_InitStubs() through the stub table is
	 * Tcl_PkgRequireEx(), so this code right here is the first code that
	 * is part of the original Tcl library in the executable that gets
	 * executed on behalf of a newly loaded stub-enabled package.
	 *
	 * One easy error for the developer/builder of a stub-enabled package
	 * to make is to forget to define USE_TCL_STUBS when compiling the
	 * package. When that happens, the package will contain symbols that
	 * are references to the Tcl library, rather than function pointers
	 * referencing the stub table. On platforms that lack backlinking,
	 * those unresolved references may cause the loading of the package to
	 * also load a second copy of the Tcl library, leading to all kinds of
	 * trouble. We would like to catch that error and report a useful
	 * message back to the user. That's what we're doing.
	 *
	 * Second, how does this work? If we reach this point, then the global
	 * variable tclEmptyStringRep has the value NULL. Compare that with
	 * the definition of tclEmptyStringRep near the top of the file
	 * generic/tclObj.c. It clearly should not have the value NULL; it
	 * should point to the char tclEmptyString. If we see it having the
	 * value NULL, then somehow we are seeing a Tcl library that isn't
	 * completely initialized, and that's an indicator for the error
	 * condition described above. (Further explanation is welcome.)
	 *
	 * Third, so what do we do about it? This situation indicates the
	 * package we just loaded wasn't properly compiled to be stub-enabled,
	 * yet it thinks it is stub-enabled (it called Tcl_InitStubs()). We
	 * want to report that the package just loaded is broken, so we want
	 * to place an error message in the interpreter result and return NULL
	 * to indicate failure to Tcl_InitStubs() so that it will also fail.
	 * (Further explanation why we don't want to Tcl_Panic() is welcome.
	 * After all, two Tcl libraries can't be a good thing!)
	 *
	 * Trouble is that's going to be tricky. We're now using a Tcl library
	 * that's not fully initialized. In particular, it doesn't have a
	 * proper value for tclEmptyStringRep. The Tcl_Obj system heavily
	 * depends on the value of tclEmptyStringRep and all of Tcl depends
	 * (increasingly) on the Tcl_Obj system, we need to correct that flaw
	 * before making the calls to set the interpreter result to the error
	 * message. That's the only flaw corrected; other problems with
	 * initialization of the Tcl library are not remedied, so be very
	 * careful about adding any other calls here without checking how they
	 * behave when initialization is incomplete.
	 */

	tclEmptyStringRep = &tclEmptyString;
	Tcl_AppendResult(interp, "Cannot load package \"", name,
		"\" in standalone executable: This package is not ",
		"compiled with stub support", NULL);
	return NULL;
    }

    /*
     * It can take up to three passes to find the package: one pass to run the
     * "package unknown" script, one to run the "package ifneeded" script for
     * a specific version, and a final pass to lookup the package loaded by
     * the "package ifneeded" script.
     */

    for (pass = 1; ; pass++) {
	pkgPtr = FindPackage(interp, name);
	if (pkgPtr->version != NULL) {
	    break;
	}

	/* 
	 * Check whether we're already attempting to load some version
	 * of this package (circular dependency detection).
	 */

	if (pkgPtr->clientData != NULL) {
	    Tcl_AppendResult(interp, "circular package dependency: ",
		    "attempt to provide ", name, " ",
		    (char *)(pkgPtr->clientData), " requires ", name, NULL);
	    if (version != NULL) {
		Tcl_AppendResult(interp, " ", version, NULL);
	    }
	    return NULL;
	}

	/*
	 * The package isn't yet present. Search the list of available
	 * versions and invoke the script for the best available version.
	 */

	bestPtr = NULL;
	for (availPtr = pkgPtr->availPtr; availPtr != NULL;
		availPtr = availPtr->nextPtr) {
	    if ((bestPtr != NULL) && (ComparePkgVersions(availPtr->version,
		    bestPtr->version, NULL) <= 0)) {
		continue;
	    }
	    if (version != NULL) {
		result = ComparePkgVersions(availPtr->version, version,
			&satisfies);
		if ((result != 0) && exact) {
		    continue;
		}
		if (!satisfies) {
		    continue;
		}
	    }
	    bestPtr = availPtr;
	}
	if (bestPtr != NULL) {
	    /*
	     * We found an ifneeded script for the package. Be careful while
	     * executing it: this could cause reentrancy, so (a) protect the
	     * script itself from deletion and (b) don't assume that bestPtr
	     * will still exist when the script completes.
	     */
	    CONST char *versionToProvide = bestPtr->version;
	    script = bestPtr->script;
	    
	    pkgPtr->clientData = (ClientData) versionToProvide;
	    Tcl_Preserve((ClientData) script);
	    Tcl_Preserve((ClientData) versionToProvide);
	    code = Tcl_GlobalEval(interp, script);
	    Tcl_Release((ClientData) script);

	    pkgPtr = FindPackage(interp, name);
	    if (code == TCL_OK) {
		Tcl_ResetResult(interp);
		if (pkgPtr->version == NULL) {
		    code = TCL_ERROR;
		    Tcl_AppendResult(interp, "attempt to provide package ",
			    name, " ", versionToProvide,
			    " failed: no version of package ", name,
			    " provided", NULL);
		} else if (0 != ComparePkgVersions(
			pkgPtr->version, versionToProvide, NULL)) {
		    code = TCL_ERROR;
		    Tcl_AppendResult(interp, "attempt to provide package ",
			    name, " ", versionToProvide, " failed: package ",
			    name, " ", pkgPtr->version, " provided instead",
			    NULL);
		}
	    } else if (code != TCL_ERROR) {
		Tcl_Obj *codePtr = Tcl_NewIntObj(code);
		Tcl_ResetResult(interp);
		Tcl_AppendResult(interp, "attempt to provide package ",
			name, " ", versionToProvide, " failed: ",
			"bad return code: ", Tcl_GetString(codePtr), NULL);
		Tcl_DecrRefCount(codePtr);
		code = TCL_ERROR;
	    }

	    if (code == TCL_ERROR) {
		TclFormatToErrorInfo(interp,
			"\n    (\"package ifneeded %s %s\" script)",
			name, versionToProvide);
	    }
	    Tcl_Release((ClientData) versionToProvide);

	    if (code != TCL_OK) {
		/*
		 * Take a non-TCL_OK code from the script as an
		 * indication the package wasn't loaded properly,
		 * so the package system should not remember an
		 * improper load.
		 *
		 * This is consistent with our returning NULL.
		 * If we're not willing to tell our caller we
		 * got a particular version, we shouldn't store
		 * that version for telling future callers either.
		 */
		if (pkgPtr->version != NULL) {
		    ckfree(pkgPtr->version);
		    pkgPtr->version = NULL;
		}
		pkgPtr->clientData = NULL;
		return NULL;
	    }
	    break;
	}

	/*
	 * Package not in the database. If there is a "package unknown"
	 * command, invoke it (but only on the first pass; after that, we
	 * should not get here in the first place).
	 */

	if (pass > 1) {
	    break;
	}
	script = ((Interp *) interp)->packageUnknown;
	if (script != NULL) {
	    Tcl_DStringInit(&command);
	    Tcl_DStringAppend(&command, script, -1);
	    Tcl_DStringAppendElement(&command, name);
	    Tcl_DStringAppend(&command, " ", 1);
	    Tcl_DStringAppend(&command, (version != NULL) ? version : "{}",
		    -1);
	    if (exact) {
		Tcl_DStringAppend(&command, " -exact", 7);
	    }
	    code = Tcl_GlobalEval(interp, Tcl_DStringValue(&command));
	    Tcl_DStringFree(&command);

	    if ((code != TCL_OK) && (code != TCL_ERROR)) {
		Tcl_Obj *codePtr = Tcl_NewIntObj(code);
		Tcl_ResetResult(interp);
		Tcl_AppendResult(interp, "bad return code: ",
			Tcl_GetString(codePtr), NULL);
		Tcl_DecrRefCount(codePtr);
		code = TCL_ERROR;
	    }
	    if (code == TCL_ERROR) {
		Tcl_AddErrorInfo(interp, "\n    (\"package unknown\" script)");
		return NULL;
	    }
	    Tcl_ResetResult(interp);
	}
    }

    if (pkgPtr->version == NULL) {
	Tcl_AppendResult(interp, "can't find package ", name, NULL);
	if (version != NULL) {
	    Tcl_AppendResult(interp, " ", version, NULL);
	}
	return NULL;
    }

    /*
     * At this point we know that the package is present. Make sure that the
     * provided version meets the current requirement.
     */

    if (version == NULL) {
	if (clientDataPtr) {
	    *clientDataPtr = pkgPtr->clientData;
	}
	return pkgPtr->version;
    }
    result = ComparePkgVersions(pkgPtr->version, version, &satisfies);
    if ((satisfies && !exact) || (result == 0)) {
	if (clientDataPtr) {
	    *clientDataPtr = pkgPtr->clientData;
	}
	return pkgPtr->version;
    }
    Tcl_AppendResult(interp, "version conflict for package \"",
	    name, "\": have ", pkgPtr->version, ", need ", version, NULL);
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *q
 * Tcl_PkgPresent / Tcl_PkgPresentEx --
 *
 *	Checks to see whether the specified package is present. If it is not
 *	then no additional action is taken.
 *
 * Results:
 *	If successful, returns the version string for the currently provided
 *	version of the package, which may be different from the "version"
 *	argument. If the caller's requirements cannot be met (e.g. the version
 *	requested conflicts with a currently provided version), NULL is
 *	returned and an error message is left in interp->result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

CONST char *
Tcl_PkgPresent(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of desired package. */
    CONST char *version,	/* Version string for desired version; NULL
				 * means use the latest version available. */
    int exact)			/* Non-zero means that only the particular
				 * version given is acceptable. Zero means use
				 * the latest compatible version. */
{
    return Tcl_PkgPresentEx(interp, name, version, exact, NULL);
}

CONST char *
Tcl_PkgPresentEx(
    Tcl_Interp *interp,		/* Interpreter in which package is now
				 * available. */
    CONST char *name,		/* Name of desired package. */
    CONST char *version,	/* Version string for desired version; NULL
				 * means use the latest version available. */
    int exact,			/* Non-zero means that only the particular
				 * version given is acceptable. Zero means use
				 * the latest compatible version. */
    ClientData *clientDataPtr)	/* Used to return the client data for this
				 * package. If it is NULL then the client data
				 * is not returned. This is unchanged if this
				 * call fails for any reason. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_HashEntry *hPtr;
    Package *pkgPtr;
    int satisfies, result;

    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, name);
    if (hPtr) {
	pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	if (pkgPtr->version != NULL) {
	    /*
	     * At this point we know that the package is present. Make sure
	     * that the provided version meets the current requirement.
	     */

	    if (version == NULL) {
		if (clientDataPtr) {
		    *clientDataPtr = pkgPtr->clientData;
		}

		return pkgPtr->version;
	    }
	    result = ComparePkgVersions(pkgPtr->version, version, &satisfies);
	    if ((satisfies && !exact) || (result == 0)) {
		if (clientDataPtr) {
		    *clientDataPtr = pkgPtr->clientData;
		}

		return pkgPtr->version;
	    }
	    Tcl_AppendResult(interp, "version conflict for package \"", name,
		    "\": have ", pkgPtr->version, ", need ", version, NULL);
	    return NULL;
	}
    }

    if (version != NULL) {
	Tcl_AppendResult(interp, "package ", name, " ", version,
		" is not present", NULL);
    } else {
	Tcl_AppendResult(interp, "package ", name, " is not present", NULL);
    }
    return NULL;
}

/*
 *----------------------------------------------------------------------
 *
 * Tcl_PackageObjCmd --
 *
 *	This function is invoked to process the "package" Tcl command. See the
 *	user documentation for details on what it does.
 *
 * Results:
 *	A standard Tcl result.
 *
 * Side effects:
 *	See the user documentation.
 *
 *----------------------------------------------------------------------
 */

	/* ARGSUSED */
int
Tcl_PackageObjCmd(
    ClientData dummy,		/* Not used. */
    Tcl_Interp *interp,		/* Current interpreter. */
    int objc,			/* Number of arguments. */
    Tcl_Obj *CONST objv[])	/* Argument objects. */
{
    static CONST char *pkgOptions[] = {
	"forget", "ifneeded", "names", "present", "provide", "require",
	"unknown", "vcompare", "versions", "vsatisfies", NULL
    };
    enum pkgOptions {
	PKG_FORGET, PKG_IFNEEDED, PKG_NAMES, PKG_PRESENT,
	PKG_PROVIDE, PKG_REQUIRE, PKG_UNKNOWN, PKG_VCOMPARE,
	PKG_VERSIONS, PKG_VSATISFIES
    };
    Interp *iPtr = (Interp *) interp;
    int optionIndex, exact, i, satisfies;
    PkgAvail *availPtr, *prevPtr;
    Package *pkgPtr;
    Tcl_HashEntry *hPtr;
    Tcl_HashSearch search;
    Tcl_HashTable *tablePtr;
    CONST char *version;
    char *argv2, *argv3, *argv4;

    if (objc < 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "option ?arg arg ...?");
	return TCL_ERROR;
    }

    if (Tcl_GetIndexFromObj(interp, objv[1], pkgOptions, "option", 0,
	    &optionIndex) != TCL_OK) {
	return TCL_ERROR;
    }
    switch ((enum pkgOptions) optionIndex) {
    case PKG_FORGET: {
	char *keyString;

	for (i = 2; i < objc; i++) {
	    keyString = Tcl_GetString(objv[i]);
	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, keyString);
	    if (hPtr == NULL) {
		continue;
	    }
	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	    Tcl_DeleteHashEntry(hPtr);
	    if (pkgPtr->version != NULL) {
		ckfree(pkgPtr->version);
	    }
	    while (pkgPtr->availPtr != NULL) {
		availPtr = pkgPtr->availPtr;
		pkgPtr->availPtr = availPtr->nextPtr;
		Tcl_EventuallyFree((ClientData)availPtr->version, TCL_DYNAMIC);
		Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
		ckfree((char *) availPtr);
	    }
	    ckfree((char *) pkgPtr);
	}
	break;
    }
    case PKG_IFNEEDED: {
	int length;

	if ((objc != 4) && (objc != 5)) {
	    Tcl_WrongNumArgs(interp, 2, objv, "package version ?script?");
	    return TCL_ERROR;
	}
	argv3 = Tcl_GetString(objv[3]);
	if (CheckVersion(interp, argv3) != TCL_OK) {
	    return TCL_ERROR;
	}
	argv2 = Tcl_GetString(objv[2]);
	if (objc == 4) {
	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv2);
	    if (hPtr == NULL) {
		return TCL_OK;
	    }
	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	} else {
	    pkgPtr = FindPackage(interp, argv2);
	}
	argv3 = Tcl_GetStringFromObj(objv[3], &length);
	for (availPtr = pkgPtr->availPtr, prevPtr = NULL; availPtr != NULL;
		prevPtr = availPtr, availPtr = availPtr->nextPtr) {
	    if (ComparePkgVersions(availPtr->version, argv3, NULL) == 0){
		if (objc == 4) {
		    Tcl_SetResult(interp, availPtr->script, TCL_VOLATILE);
		    return TCL_OK;
		}
		Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
		break;
	    }
	}
	if (objc == 4) {
	    return TCL_OK;
	}
	if (availPtr == NULL) {
	    availPtr = (PkgAvail *) ckalloc(sizeof(PkgAvail));
	    availPtr->version = ckalloc((unsigned) (length + 1));
	    strcpy(availPtr->version, argv3);
	    if (prevPtr == NULL) {
		availPtr->nextPtr = pkgPtr->availPtr;
		pkgPtr->availPtr = availPtr;
	    } else {
		availPtr->nextPtr = prevPtr->nextPtr;
		prevPtr->nextPtr = availPtr;
	    }
	}
	argv4 = Tcl_GetStringFromObj(objv[4], &length);
	availPtr->script = ckalloc((unsigned) (length + 1));
	strcpy(availPtr->script, argv4);
	break;
    }
    case PKG_NAMES:
	if (objc != 2) {
	    Tcl_WrongNumArgs(interp, 2, objv, NULL);
	    return TCL_ERROR;
	}
	tablePtr = &iPtr->packageTable;
	for (hPtr = Tcl_FirstHashEntry(tablePtr, &search); hPtr != NULL;
		hPtr = Tcl_NextHashEntry(&search)) {
	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	    if ((pkgPtr->version != NULL) || (pkgPtr->availPtr != NULL)) {
		Tcl_AppendElement(interp, Tcl_GetHashKey(tablePtr, hPtr));
	    }
	}
	break;
    case PKG_PRESENT:
	if (objc < 3) {
	presentSyntax:
	    Tcl_WrongNumArgs(interp, 2, objv, "?-exact? package ?version?");
	    return TCL_ERROR;
	}
	argv2 = Tcl_GetString(objv[2]);
	if ((argv2[0] == '-') && (strcmp(argv2, "-exact") == 0)) {
	    exact = 1;
	} else {
	    exact = 0;
	}
	version = NULL;
	if (objc == (4 + exact)) {
	    version = Tcl_GetString(objv[3 + exact]);
	    if (CheckVersion(interp, version) != TCL_OK) {
		return TCL_ERROR;
	    }
	} else if ((objc != 3) || exact) {
	    goto presentSyntax;
	}
	if (exact) {
	    argv3 = Tcl_GetString(objv[3]);
	    version = Tcl_PkgPresent(interp, argv3, version, exact);
	} else {
	    version = Tcl_PkgPresent(interp, argv2, version, exact);
	}
	if (version == NULL) {
	    return TCL_ERROR;
	}
	Tcl_SetObjResult( interp, Tcl_NewStringObj( version, -1 ) );
	break;
    case PKG_PROVIDE:
	if ((objc != 3) && (objc != 4)) {
	    Tcl_WrongNumArgs(interp, 2, objv, "package ?version?");
	    return TCL_ERROR;
	}
	argv2 = Tcl_GetString(objv[2]);
	if (objc == 3) {
	    hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv2);
	    if (hPtr != NULL) {
		pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
		if (pkgPtr->version != NULL) {
		    Tcl_SetResult(interp, pkgPtr->version, TCL_VOLATILE);
		}
	    }
	    return TCL_OK;
	}
	argv3 = Tcl_GetString(objv[3]);
	if (CheckVersion(interp, argv3) != TCL_OK) {
	    return TCL_ERROR;
	}
	return Tcl_PkgProvide(interp, argv2, argv3);
    case PKG_REQUIRE:
	if (objc < 3) {
	requireSyntax:
	    Tcl_WrongNumArgs(interp, 2, objv, "?-exact? package ?version?");
	    return TCL_ERROR;
	}
	argv2 = Tcl_GetString(objv[2]);
	if ((argv2[0] == '-') && (strcmp(argv2, "-exact") == 0)) {
	    exact = 1;
	} else {
	    exact = 0;
	}
	version = NULL;
	if (objc == (4 + exact)) {
	    version = Tcl_GetString(objv[3 + exact]);
	    if (CheckVersion(interp, version) != TCL_OK) {
		return TCL_ERROR;
	    }
	} else if ((objc != 3) || exact) {
	    goto requireSyntax;
	}
	if (exact) {
	    argv3 = Tcl_GetString(objv[3]);
	    version = Tcl_PkgRequire(interp, argv3, version, exact);
	} else {
	    version = Tcl_PkgRequire(interp, argv2, version, exact);
	}
	if (version == NULL) {
	    return TCL_ERROR;
	}
	Tcl_SetObjResult(interp, Tcl_NewStringObj(version, -1));
	break;
    case PKG_UNKNOWN: {
	int length;

	if (objc == 2) {
	    if (iPtr->packageUnknown != NULL) {
		Tcl_SetResult(interp, iPtr->packageUnknown, TCL_VOLATILE);
	    }
	} else if (objc == 3) {
	    if (iPtr->packageUnknown != NULL) {
		ckfree(iPtr->packageUnknown);
	    }
	    argv2 = Tcl_GetStringFromObj(objv[2], &length);
	    if (argv2[0] == 0) {
		iPtr->packageUnknown = NULL;
	    } else {
		iPtr->packageUnknown = (char *) ckalloc((unsigned) (length+1));
		strcpy(iPtr->packageUnknown, argv2);
	    }
	} else {
	    Tcl_WrongNumArgs(interp, 2, objv, "?command?");
	    return TCL_ERROR;
	}
	break;
    }
    case PKG_VCOMPARE:
	if (objc != 4) {
	    Tcl_WrongNumArgs(interp, 2, objv, "version1 version2");
	    return TCL_ERROR;
	}
	argv3 = Tcl_GetString(objv[3]);
	argv2 = Tcl_GetString(objv[2]);
	if ((CheckVersion(interp, argv2) != TCL_OK)
		|| (CheckVersion(interp, argv3) != TCL_OK)) {
	    return TCL_ERROR;
	}
	Tcl_SetObjResult(interp,
		Tcl_NewIntObj(ComparePkgVersions(argv2, argv3, NULL)));
	break;
    case PKG_VERSIONS:
	if (objc != 3) {
	    Tcl_WrongNumArgs(interp, 2, objv, "package");
	    return TCL_ERROR;
	}
	argv2 = Tcl_GetString(objv[2]);
	hPtr = Tcl_FindHashEntry(&iPtr->packageTable, argv2);
	if (hPtr != NULL) {
	    pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	    for (availPtr = pkgPtr->availPtr; availPtr != NULL;
		    availPtr = availPtr->nextPtr) {
		Tcl_AppendElement(interp, availPtr->version);
	    }
	}
	break;
    case PKG_VSATISFIES:
	if (objc != 4) {
	    Tcl_WrongNumArgs(interp, 2, objv, "version1 version2");
	    return TCL_ERROR;
	}
	argv3 = Tcl_GetString(objv[3]);
	argv2 = Tcl_GetString(objv[2]);
	if ((CheckVersion(interp, argv2) != TCL_OK)
		|| (CheckVersion(interp, argv3) != TCL_OK)) {
	    return TCL_ERROR;
	}
	ComparePkgVersions(argv2, argv3, &satisfies);
	Tcl_SetObjResult(interp, Tcl_NewBooleanObj(satisfies));
	break;
    default:
	Tcl_Panic("Tcl_PackageObjCmd: bad option index to pkgOptions");
    }
    return TCL_OK;
}

/*
 *----------------------------------------------------------------------
 *
 * FindPackage --
 *
 *	This function finds the Package record for a particular package in a
 *	particular interpreter, creating a record if one doesn't already
 *	exist.
 *
 * Results:
 *	The return value is a pointer to the Package record for the package.
 *
 * Side effects:
 *	A new Package record may be created.
 *
 *----------------------------------------------------------------------
 */

static Package *
FindPackage(
    Tcl_Interp *interp,		/* Interpreter to use for package lookup. */
    CONST char *name)		/* Name of package to fine. */
{
    Interp *iPtr = (Interp *) interp;
    Tcl_HashEntry *hPtr;
    int new;
    Package *pkgPtr;

    hPtr = Tcl_CreateHashEntry(&iPtr->packageTable, name, &new);
    if (new) {
	pkgPtr = (Package *) ckalloc(sizeof(Package));
	pkgPtr->version = NULL;
	pkgPtr->availPtr = NULL;
	pkgPtr->clientData = NULL;
	Tcl_SetHashValue(hPtr, pkgPtr);
    } else {
	pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
    }
    return pkgPtr;
}

/*
 *----------------------------------------------------------------------
 *
 * TclFreePackageInfo --
 *
 *	This function is called during interpreter deletion to free all of the
 *	package-related information for the interpreter.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Memory is freed.
 *
 *----------------------------------------------------------------------
 */

void
TclFreePackageInfo(
    Interp *iPtr)		/* Interpereter that is being deleted. */
{
    Package *pkgPtr;
    Tcl_HashSearch search;
    Tcl_HashEntry *hPtr;
    PkgAvail *availPtr;

    for (hPtr = Tcl_FirstHashEntry(&iPtr->packageTable, &search);
	    hPtr != NULL; hPtr = Tcl_NextHashEntry(&search)) {
	pkgPtr = (Package *) Tcl_GetHashValue(hPtr);
	if (pkgPtr->version != NULL) {
	    ckfree(pkgPtr->version);
	}
	while (pkgPtr->availPtr != NULL) {
	    availPtr = pkgPtr->availPtr;
	    pkgPtr->availPtr = availPtr->nextPtr;
	    Tcl_EventuallyFree((ClientData)availPtr->version, TCL_DYNAMIC);
	    Tcl_EventuallyFree((ClientData)availPtr->script, TCL_DYNAMIC);
	    ckfree((char *) availPtr);
	}
	ckfree((char *) pkgPtr);
    }
    Tcl_DeleteHashTable(&iPtr->packageTable);
    if (iPtr->packageUnknown != NULL) {
	ckfree(iPtr->packageUnknown);
    }
}

/*
 *----------------------------------------------------------------------
 *
 * CheckVersion --
 *
 *	This function checks to see whether a version number has valid syntax.
 *
 * Results:
 *	If string is a properly formed version number the TCL_OK is returned.
 *	Otherwise TCL_ERROR is returned and an error message is left in the
 *	interp's result.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
CheckVersion(
    Tcl_Interp *interp,		/* Used for error reporting. */
    CONST char *string)		/* Supposedly a version number, which is
				 * groups of decimal digits separated by
				 * dots. */
{
    CONST char *p = string;
    char prevChar;

    if (!isdigit(UCHAR(*p))) {	/* INTL: digit */
	goto error;
    }
    for (prevChar = *p, p++; *p != 0; p++) {
	if (!isdigit(UCHAR(*p)) &&
		((*p != '.') || (prevChar == '.'))) { /* INTL: digit */
	    goto error;
	}
	prevChar = *p;
    }
    if (prevChar != '.') {
	return TCL_OK;
    }

  error:
    Tcl_AppendResult(interp, "expected version number but got \"", string,
	    "\"", NULL);
    return TCL_ERROR;
}

/*
 *----------------------------------------------------------------------
 *
 * ComparePkgVersions --
 *
 *	This function compares two version numbers.
 *
 * Results:
 *	The return value is -1 if v1 is less than v2, 0 if the two version
 *	numbers are the same, and 1 if v1 is greater than v2. If *satPtr is
 *	non-NULL, the word it points to is filled in with 1 if v2 >= v1 and
 *	both numbers have the same major number or 0 otherwise.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

static int
ComparePkgVersions(
    CONST char *v1,
    CONST char *v2,		/* Versions strings, of form 2.1.3 (any number
				 * of version numbers). */
    int *satPtr)		/* If non-null, the word pointed to is filled
				 * in with a 0/1 value. 1 means v1 "satisfies"
				 * v2: v1 is greater than or equal to v2 and
				 * both version numbers have the same major
				 * number. */
{
    int thisIsMajor, n1, n2;

    /*
     * Each iteration of the following loop processes one number from each
     * string, terminated by a ".". If those numbers don't match then the
     * comparison is over; otherwise, we loop back for the next number.
     */

    thisIsMajor = 1;
    while (1) {
	/*
	 * Parse one decimal number from the front of each string.
	 */

	n1 = n2 = 0;
	while ((*v1 != 0) && (*v1 != '.')) {
	    n1 = 10*n1 + (*v1 - '0');
	    v1++;
	}
	while ((*v2 != 0) && (*v2 != '.')) {
	    n2 = 10*n2 + (*v2 - '0');
	    v2++;
	}

	/*
	 * Compare and go on to the next version number if the current numbers
	 * match.
	 */

	if (n1 != n2) {
	    break;
	}
	if (*v1 != 0) {
	    v1++;
	} else if (*v2 == 0) {
	    break;
	}
	if (*v2 != 0) {
	    v2++;
	}
	thisIsMajor = 0;
    }
    if (satPtr != NULL) {
	*satPtr = (n1 == n2) || ((n1 > n2) && !thisIsMajor);
    }
    if (n1 > n2) {
	return 1;
    } else if (n1 == n2) {
	return 0;
    } else {
	return -1;
    }
}

/*
 * Local Variables:
 * mode: c
 * c-basic-offset: 4
 * fill-column: 78
 * End:
 */