about summary refs log tree commit diff
path: root/src/nix-store/nix-store.cc
blob: 350a4ce0fa379ff87c5fd790060fdd0d37380106 (plain) (blame)
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
#include "globals.hh"
#include "misc.hh"
#include "archive.hh"
#include "shared.hh"
#include "dotgraph.hh"
#include "xmlgraph.hh"
#include "local-store.hh"
#include "util.hh"
#include "serve-protocol.hh"

#include <iostream>
#include <algorithm>
#include <cstdio>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <bzlib.h>


using namespace nix;
using std::cin;
using std::cout;


typedef void (* Operation) (Strings opFlags, Strings opArgs);


void printHelp()
{
    showManPage("nix-store");
}


static Path gcRoot;
static int rootNr = 0;
static bool indirectRoot = false;
static bool noOutput = false;


LocalStore & ensureLocalStore()
{
    LocalStore * store2(dynamic_cast<LocalStore *>(store.get()));
    if (!store2) throw Error("you don't have sufficient rights to use this command");
    return *store2;
}


static Path useDeriver(Path path)
{
    if (!isDerivation(path)) {
        path = store->queryDeriver(path);
        if (path == "")
            throw Error(format("deriver of path `%1%' is not known") % path);
    }
    return path;
}


/* Realise the given path.  For a derivation that means build it; for
   other paths it means ensure their validity. */
static PathSet realisePath(const Path & path, bool build = true)
{
    DrvPathWithOutputs p = parseDrvPathWithOutputs(path);

    if (isDerivation(p.first)) {
        if (build) store->buildPaths(singleton<PathSet>(path));
        Derivation drv = derivationFromPath(*store, p.first);
        rootNr++;

        if (p.second.empty())
            foreach (DerivationOutputs::iterator, i, drv.outputs) p.second.insert(i->first);

        PathSet outputs;
        foreach (StringSet::iterator, j, p.second) {
            DerivationOutputs::iterator i = drv.outputs.find(*j);
            if (i == drv.outputs.end())
                throw Error(format("derivation `%1%' does not have an output named `%2%'") % p.first % *j);
            Path outPath = i->second.path;
            if (gcRoot == "")
                printGCWarning();
            else {
                Path rootName = gcRoot;
                if (rootNr > 1) rootName += "-" + int2String(rootNr);
                if (i->first != "out") rootName += "-" + i->first;
                outPath = addPermRoot(*store, outPath, rootName, indirectRoot);
            }
            outputs.insert(outPath);
        }
        return outputs;
    }

    else {
        if (build) store->ensurePath(path);
        else if (!store->isValidPath(path)) throw Error(format("path `%1%' does not exist and cannot be created") % path);
        return singleton<PathSet>(path);
    }
}


/* Realise the given paths. */
static void opRealise(Strings opFlags, Strings opArgs)
{
    bool dryRun = false;
    bool repair = false;
    bool ignoreUnknown = false;

    foreach (Strings::iterator, i, opFlags)
        if (*i == "--dry-run") dryRun = true;
        else if (*i == "--repair") repair = true;
        else if (*i == "--ignore-unknown") ignoreUnknown = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    Paths paths;
    foreach (Strings::iterator, i, opArgs) {
        DrvPathWithOutputs p = parseDrvPathWithOutputs(*i);
        paths.push_back(makeDrvPathWithOutputs(followLinksToStorePath(p.first), p.second));
    }

    unsigned long long downloadSize, narSize;
    PathSet willBuild, willSubstitute, unknown;
    queryMissing(*store, PathSet(paths.begin(), paths.end()),
        willBuild, willSubstitute, unknown, downloadSize, narSize);

    if (ignoreUnknown) {
        Paths paths2;
        foreach (Paths::iterator, i, paths)
            if (unknown.find(*i) == unknown.end()) paths2.push_back(*i);
        paths = paths2;
        unknown = PathSet();
    }

    printMissing(willBuild, willSubstitute, unknown, downloadSize, narSize);

    if (dryRun) return;

    /* Build all paths at the same time to exploit parallelism. */
    store->buildPaths(PathSet(paths.begin(), paths.end()), repair);

    if (!ignoreUnknown)
        foreach (Paths::iterator, i, paths) {
            PathSet paths = realisePath(*i, false);
            if (!noOutput)
                foreach (PathSet::iterator, j, paths)
                    cout << format("%1%\n") % *j;
        }
}


/* Add files to the Nix store and print the resulting paths. */
static void opAdd(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");

    for (Strings::iterator i = opArgs.begin(); i != opArgs.end(); ++i)
        cout << format("%1%\n") % store->addToStore(*i);
}


/* Preload the output of a fixed-output derivation into the Nix
   store. */
static void opAddFixed(Strings opFlags, Strings opArgs)
{
    bool recursive = false;

    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--recursive") recursive = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    if (opArgs.empty())
        throw UsageError("first argument must be hash algorithm");

    HashType hashAlgo = parseHashType(opArgs.front());
    opArgs.pop_front();

    for (Strings::iterator i = opArgs.begin(); i != opArgs.end(); ++i)
        cout << format("%1%\n") % store->addToStore(*i, recursive, hashAlgo);
}


/* Hack to support caching in `nix-prefetch-url'. */
static void opPrintFixedPath(Strings opFlags, Strings opArgs)
{
    bool recursive = false;

    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--recursive") recursive = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    if (opArgs.size() != 3)
        throw UsageError(format("`--print-fixed-path' requires three arguments"));

    Strings::iterator i = opArgs.begin();
    HashType hashAlgo = parseHashType(*i++);
    string hash = *i++;
    string name = *i++;

    cout << format("%1%\n") %
        makeFixedOutputPath(recursive, hashAlgo,
            parseHash16or32(hashAlgo, hash), name);
}


static PathSet maybeUseOutputs(const Path & storePath, bool useOutput, bool forceRealise)
{
    if (forceRealise) realisePath(storePath);
    if (useOutput && isDerivation(storePath)) {
        Derivation drv = derivationFromPath(*store, storePath);
        PathSet outputs;
        foreach (DerivationOutputs::iterator, i, drv.outputs)
            outputs.insert(i->second.path);
        return outputs;
    }
    else return singleton<PathSet>(storePath);
}


/* Some code to print a tree representation of a derivation dependency
   graph.  Topological sorting is used to keep the tree relatively
   flat. */

const string treeConn = "+---";
const string treeLine = "|   ";
const string treeNull = "    ";


static void printTree(const Path & path,
    const string & firstPad, const string & tailPad, PathSet & done)
{
    if (done.find(path) != done.end()) {
        cout << format("%1%%2% [...]\n") % firstPad % path;
        return;
    }
    done.insert(path);

    cout << format("%1%%2%\n") % firstPad % path;

    PathSet references;
    store->queryReferences(path, references);

    /* Topologically sort under the relation A < B iff A \in
       closure(B).  That is, if derivation A is an (possibly indirect)
       input of B, then A is printed first.  This has the effect of
       flattening the tree, preventing deeply nested structures.  */
    Paths sorted = topoSortPaths(*store, references);
    reverse(sorted.begin(), sorted.end());

    foreach (Paths::iterator, i, sorted) {
        Paths::iterator j = i; ++j;
        printTree(*i, tailPad + treeConn,
            j == sorted.end() ? tailPad + treeNull : tailPad + treeLine,
            done);
    }
}


/* Perform various sorts of queries. */
static void opQuery(Strings opFlags, Strings opArgs)
{
    enum { qOutputs, qRequisites, qReferences, qReferrers
         , qReferrersClosure, qDeriver, qBinding, qHash, qSize
         , qTree, qGraph, qXml, qResolve, qRoots } query = qOutputs;
    bool useOutput = false;
    bool includeOutputs = false;
    bool forceRealise = false;
    string bindingName;

    foreach (Strings::iterator, i, opFlags)
        if (*i == "--outputs") query = qOutputs;
        else if (*i == "--requisites" || *i == "-R") query = qRequisites;
        else if (*i == "--references") query = qReferences;
        else if (*i == "--referrers" || *i == "--referers") query = qReferrers;
        else if (*i == "--referrers-closure" || *i == "--referers-closure") query = qReferrersClosure;
        else if (*i == "--deriver" || *i == "-d") query = qDeriver;
        else if (*i == "--binding" || *i == "-b") {
            if (opArgs.size() == 0)
                throw UsageError("expected binding name");
            bindingName = opArgs.front();
            opArgs.pop_front();
            query = qBinding;
        }
        else if (*i == "--hash") query = qHash;
        else if (*i == "--size") query = qSize;
        else if (*i == "--tree") query = qTree;
        else if (*i == "--graph") query = qGraph;
        else if (*i == "--xml") query = qXml;
        else if (*i == "--resolve") query = qResolve;
        else if (*i == "--roots") query = qRoots;
        else if (*i == "--use-output" || *i == "-u") useOutput = true;
        else if (*i == "--force-realise" || *i == "--force-realize" || *i == "-f") forceRealise = true;
        else if (*i == "--include-outputs") includeOutputs = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    switch (query) {

        case qOutputs: {
            foreach (Strings::iterator, i, opArgs) {
                *i = followLinksToStorePath(*i);
                if (forceRealise) realisePath(*i);
                Derivation drv = derivationFromPath(*store, *i);
                foreach (DerivationOutputs::iterator, j, drv.outputs)
                    cout << format("%1%\n") % j->second.path;
            }
            break;
        }

        case qRequisites:
        case qReferences:
        case qReferrers:
        case qReferrersClosure: {
            PathSet paths;
            foreach (Strings::iterator, i, opArgs) {
                PathSet ps = maybeUseOutputs(followLinksToStorePath(*i), useOutput, forceRealise);
                foreach (PathSet::iterator, j, ps) {
                    if (query == qRequisites) computeFSClosure(*store, *j, paths, false, includeOutputs);
                    else if (query == qReferences) store->queryReferences(*j, paths);
                    else if (query == qReferrers) store->queryReferrers(*j, paths);
                    else if (query == qReferrersClosure) computeFSClosure(*store, *j, paths, true);
                }
            }
            Paths sorted = topoSortPaths(*store, paths);
            for (Paths::reverse_iterator i = sorted.rbegin();
                 i != sorted.rend(); ++i)
                cout << format("%s\n") % *i;
            break;
        }

        case qDeriver:
            foreach (Strings::iterator, i, opArgs) {
                Path deriver = store->queryDeriver(followLinksToStorePath(*i));
                cout << format("%1%\n") %
                    (deriver == "" ? "unknown-deriver" : deriver);
            }
            break;

        case qBinding:
            foreach (Strings::iterator, i, opArgs) {
                Path path = useDeriver(followLinksToStorePath(*i));
                Derivation drv = derivationFromPath(*store, path);
                StringPairs::iterator j = drv.env.find(bindingName);
                if (j == drv.env.end())
                    throw Error(format("derivation `%1%' has no environment binding named `%2%'")
                        % path % bindingName);
                cout << format("%1%\n") % j->second;
            }
            break;

        case qHash:
        case qSize:
            foreach (Strings::iterator, i, opArgs) {
                PathSet paths = maybeUseOutputs(followLinksToStorePath(*i), useOutput, forceRealise);
                foreach (PathSet::iterator, j, paths) {
                    ValidPathInfo info = store->queryPathInfo(*j);
                    if (query == qHash) {
                        assert(info.hash.type == htSHA256);
                        cout << format("sha256:%1%\n") % printHash32(info.hash);
                    } else if (query == qSize)
                        cout << format("%1%\n") % info.narSize;
                }
            }
            break;

        case qTree: {
            PathSet done;
            foreach (Strings::iterator, i, opArgs)
                printTree(followLinksToStorePath(*i), "", "", done);
            break;
        }

        case qGraph: {
            PathSet roots;
            foreach (Strings::iterator, i, opArgs) {
                PathSet paths = maybeUseOutputs(followLinksToStorePath(*i), useOutput, forceRealise);
                roots.insert(paths.begin(), paths.end());
            }
            printDotGraph(roots);
            break;
        }

        case qXml: {
            PathSet roots;
            foreach (Strings::iterator, i, opArgs) {
                PathSet paths = maybeUseOutputs(followLinksToStorePath(*i), useOutput, forceRealise);
                roots.insert(paths.begin(), paths.end());
            }
            printXmlGraph(roots);
            break;
        }

        case qResolve: {
            foreach (Strings::iterator, i, opArgs)
                cout << format("%1%\n") % followLinksToStorePath(*i);
            break;
        }

        case qRoots: {
            PathSet referrers;
            foreach (Strings::iterator, i, opArgs) {
                PathSet paths = maybeUseOutputs(followLinksToStorePath(*i), useOutput, forceRealise);
                foreach (PathSet::iterator, j, paths)
                    computeFSClosure(*store, *j, referrers, true,
                        settings.gcKeepOutputs, settings.gcKeepDerivations);
            }
            Roots roots = store->findRoots();
            foreach (Roots::iterator, i, roots)
                if (referrers.find(i->second) != referrers.end())
                    cout << format("%1%\n") % i->first;
            break;
        }

        default:
            abort();
    }
}


static string shellEscape(const string & s)
{
    string r;
    foreach (string::const_iterator, i, s)
        if (*i == '\'') r += "'\\''"; else r += *i;
    return r;
}


static void opPrintEnv(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() != 1) throw UsageError("`--print-env' requires one derivation store path");

    Path drvPath = opArgs.front();
    Derivation drv = derivationFromPath(*store, drvPath);

    /* Print each environment variable in the derivation in a format
       that can be sourced by the shell. */
    foreach (StringPairs::iterator, i, drv.env)
        cout << format("export %1%; %1%='%2%'\n") % i->first % shellEscape(i->second);

    /* Also output the arguments.  This doesn't preserve whitespace in
       arguments. */
    cout << "export _args; _args='";
    foreach (Strings::iterator, i, drv.args) {
        if (i != drv.args.begin()) cout << ' ';
        cout << shellEscape(*i);
    }
    cout << "'\n";
}


static void opReadLog(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");

    foreach (Strings::iterator, i, opArgs) {
        Path path = useDeriver(followLinksToStorePath(*i));

        for (int j = 0; j <= 2; j++) {
            if (j == 2) throw Error(format("build log of derivation `%1%' is not available") % path);

            string baseName = baseNameOf(path);
            Path logPath =
                j == 0
                ? (format("%1%/%2%/%3%/%4%") % settings.nixLogDir % drvsLogDir % string(baseName, 0, 2) % string(baseName, 2)).str()
                : (format("%1%/%2%/%3%") % settings.nixLogDir % drvsLogDir % baseName).str();
            Path logBz2Path = logPath + ".bz2";

            if (pathExists(logPath)) {
                /* !!! Make this run in O(1) memory. */
                string log = readFile(logPath);
                writeFull(STDOUT_FILENO, (const unsigned char *) log.data(), log.size());
                break;
            }

            else if (pathExists(logBz2Path)) {
                AutoCloseFD fd = open(logBz2Path.c_str(), O_RDONLY);
                FILE * f = 0;
                if (fd == -1 || (f = fdopen(fd.borrow(), "r")) == 0)
                    throw SysError(format("opening file `%1%'") % logBz2Path);
                int err;
                BZFILE * bz = BZ2_bzReadOpen(&err, f, 0, 0, 0, 0);
                if (!bz) throw Error(format("cannot open bzip2 file `%1%'") % logBz2Path);
                unsigned char buf[128 * 1024];
                do {
                    int n = BZ2_bzRead(&err, bz, buf, sizeof(buf));
                    if (err != BZ_OK && err != BZ_STREAM_END)
                        throw Error(format("error reading bzip2 file `%1%'") % logBz2Path);
                    writeFull(STDOUT_FILENO, buf, n);
                } while (err != BZ_STREAM_END);
                BZ2_bzReadClose(&err, bz);
                break;
            }
        }
    }
}


static void opDumpDB(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (!opArgs.empty())
        throw UsageError("no arguments expected");
    PathSet validPaths = store->queryAllValidPaths();
    foreach (PathSet::iterator, i, validPaths)
        cout << store->makeValidityRegistration(singleton<PathSet>(*i), true, true);
}


static void registerValidity(bool reregister, bool hashGiven, bool canonicalise)
{
    ValidPathInfos infos;

    while (1) {
        ValidPathInfo info = decodeValidPathInfo(cin, hashGiven);
        if (info.path == "") break;
        if (!store->isValidPath(info.path) || reregister) {
            /* !!! races */
            if (canonicalise)
                canonicalisePathMetaData(info.path, -1);
            if (!hashGiven) {
                HashResult hash = hashPath(htSHA256, info.path);
                info.hash = hash.first;
                info.narSize = hash.second;
            }
            infos.push_back(info);
        }
    }

    ensureLocalStore().registerValidPaths(infos);
}


static void opLoadDB(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (!opArgs.empty())
        throw UsageError("no arguments expected");
    registerValidity(true, true, false);
}


static void opRegisterValidity(Strings opFlags, Strings opArgs)
{
    bool reregister = false; // !!! maybe this should be the default
    bool hashGiven = false;

    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--reregister") reregister = true;
        else if (*i == "--hash-given") hashGiven = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    if (!opArgs.empty()) throw UsageError("no arguments expected");

    registerValidity(reregister, hashGiven, true);
}


static void opCheckValidity(Strings opFlags, Strings opArgs)
{
    bool printInvalid = false;

    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--print-invalid") printInvalid = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    for (Strings::iterator i = opArgs.begin();
         i != opArgs.end(); ++i)
    {
        Path path = followLinksToStorePath(*i);
        if (!store->isValidPath(path)) {
            if (printInvalid)
                cout << format("%1%\n") % path;
            else
                throw Error(format("path `%1%' is not valid") % path);
        }
    }
}


static string showBytes(unsigned long long bytes)
{
    return (format("%.2f MiB") % (bytes / (1024.0 * 1024.0))).str();
}


struct PrintFreed
{
    bool show;
    const GCResults & results;
    PrintFreed(bool show, const GCResults & results)
        : show(show), results(results) { }
    ~PrintFreed()
    {
        if (show)
            cout << format("%1% store paths deleted, %2% freed\n")
                % results.paths.size()
                % showBytes(results.bytesFreed);
    }
};


static void opGC(Strings opFlags, Strings opArgs)
{
    bool printRoots = false;
    GCOptions options;
    options.action = GCOptions::gcDeleteDead;

    GCResults results;

    /* Do what? */
    foreach (Strings::iterator, i, opFlags)
        if (*i == "--print-roots") printRoots = true;
        else if (*i == "--print-live") options.action = GCOptions::gcReturnLive;
        else if (*i == "--print-dead") options.action = GCOptions::gcReturnDead;
        else if (*i == "--delete") options.action = GCOptions::gcDeleteDead;
        else if (*i == "--max-freed") {
            long long maxFreed = getIntArg<long long>(*i, i, opFlags.end());
            options.maxFreed = maxFreed >= 0 ? maxFreed : 0;
        }
        else throw UsageError(format("bad sub-operation `%1%' in GC") % *i);

    if (!opArgs.empty()) throw UsageError("no arguments expected");

    if (printRoots) {
        Roots roots = store->findRoots();
        foreach (Roots::iterator, i, roots)
            cout << i->first << " -> " << i->second << std::endl;
    }

    else {
        PrintFreed freed(options.action == GCOptions::gcDeleteDead, results);
        store->collectGarbage(options, results);

        if (options.action != GCOptions::gcDeleteDead)
            foreach (PathSet::iterator, i, results.paths)
                cout << *i << std::endl;
    }
}


/* Remove paths from the Nix store if possible (i.e., if they do not
   have any remaining referrers and are not reachable from any GC
   roots). */
static void opDelete(Strings opFlags, Strings opArgs)
{
    GCOptions options;
    options.action = GCOptions::gcDeleteSpecific;

    foreach (Strings::iterator, i, opFlags)
        if (*i == "--ignore-liveness") options.ignoreLiveness = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    foreach (Strings::iterator, i, opArgs)
        options.pathsToDelete.insert(followLinksToStorePath(*i));

    GCResults results;
    PrintFreed freed(true, results);
    store->collectGarbage(options, results);
}


/* Dump a path as a Nix archive.  The archive is written to standard
   output. */
static void opDump(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() != 1) throw UsageError("only one argument allowed");

    FdSink sink(STDOUT_FILENO);
    string path = *opArgs.begin();
    dumpPath(path, sink);
}


/* Restore a value from a Nix archive.  The archive is read from
   standard input. */
static void opRestore(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() != 1) throw UsageError("only one argument allowed");

    FdSource source(STDIN_FILENO);
    restorePath(*opArgs.begin(), source);
}


static void opExport(Strings opFlags, Strings opArgs)
{
    bool sign = false;
    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--sign") sign = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    FdSink sink(STDOUT_FILENO);
    Paths sorted = topoSortPaths(*store, PathSet(opArgs.begin(), opArgs.end()));
    reverse(sorted.begin(), sorted.end());
    exportPaths(*store, sorted, sign, sink);
}


static void opImport(Strings opFlags, Strings opArgs)
{
    bool requireSignature = false;
    foreach (Strings::iterator, i, opFlags)
        if (*i == "--require-signature") requireSignature = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    if (!opArgs.empty()) throw UsageError("no arguments expected");

    FdSource source(STDIN_FILENO);
    Paths paths = store->importPaths(requireSignature, source);

    foreach (Paths::iterator, i, paths)
        cout << format("%1%\n") % *i << std::flush;
}


/* Initialise the Nix databases. */
static void opInit(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (!opArgs.empty())
        throw UsageError("no arguments expected");
    /* Doesn't do anything right now; database tables are initialised
       automatically. */
}


/* Verify the consistency of the Nix environment. */
static void opVerify(Strings opFlags, Strings opArgs)
{
    if (!opArgs.empty())
        throw UsageError("no arguments expected");

    bool checkContents = false;
    bool repair = false;

    for (Strings::iterator i = opFlags.begin();
         i != opFlags.end(); ++i)
        if (*i == "--check-contents") checkContents = true;
        else if (*i == "--repair") repair = true;
        else throw UsageError(format("unknown flag `%1%'") % *i);

    if (ensureLocalStore().verifyStore(checkContents, repair)) {
        printMsg(lvlError, "warning: not all errors were fixed");
        exitCode = 1;
    }
}


/* Verify whether the contents of the given store path have not changed. */
static void opVerifyPath(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty())
        throw UsageError("no flags expected");

    foreach (Strings::iterator, i, opArgs) {
        Path path = followLinksToStorePath(*i);
        printMsg(lvlTalkative, format("checking path `%1%'...") % path);
        ValidPathInfo info = store->queryPathInfo(path);
        HashResult current = hashPath(info.hash.type, path);
        if (current.first != info.hash) {
            printMsg(lvlError,
                format("path `%1%' was modified! expected hash `%2%', got `%3%'")
                % path % printHash(info.hash) % printHash(current.first));
            exitCode = 1;
        }
    }
}


/* Repair the contents of the given path by redownloading it using a
   substituter (if available). */
static void opRepairPath(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty())
        throw UsageError("no flags expected");

    foreach (Strings::iterator, i, opArgs) {
        Path path = followLinksToStorePath(*i);
        ensureLocalStore().repairPath(path);
    }
}


static void showOptimiseStats(OptimiseStats & stats)
{
    printMsg(lvlError,
        format("%1% freed by hard-linking %2% files; there are %3% files with equal contents out of %4% files in total")
        % showBytes(stats.bytesFreed)
        % stats.filesLinked
        % stats.sameContents
        % stats.totalFiles);
}


/* Optimise the disk space usage of the Nix store by hard-linking
   files with the same contents. */
static void opOptimise(Strings opFlags, Strings opArgs)
{
    if (!opArgs.empty() || !opFlags.empty())
        throw UsageError("no arguments expected");

    OptimiseStats stats;
    try {
        ensureLocalStore().optimiseStore(stats);
    } catch (...) {
        showOptimiseStats(stats);
        throw;
    }
    showOptimiseStats(stats);
}


static void opQueryFailedPaths(Strings opFlags, Strings opArgs)
{
    if (!opArgs.empty() || !opFlags.empty())
        throw UsageError("no arguments expected");
    PathSet failed = store->queryFailedPaths();
    foreach (PathSet::iterator, i, failed)
        cout << format("%1%\n") % *i;
}


static void opClearFailedPaths(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty())
        throw UsageError("no flags expected");
    store->clearFailedPaths(PathSet(opArgs.begin(), opArgs.end()));
}


// Serve the nix store in a way usable by a restricted ssh user
static void opServe(Strings opFlags, Strings opArgs)
{
    if (!opArgs.empty() || !opFlags.empty())
        throw UsageError("no arguments or flags expected");

    FdSource in(STDIN_FILENO);
    FdSink out(STDOUT_FILENO);

    /* Exchange the greeting. */
    unsigned int magic = readInt(in);
    if (magic != SERVE_MAGIC_1) throw Error("protocol mismatch");
    writeInt(SERVE_MAGIC_2, out);
    writeInt(SERVE_PROTOCOL_VERSION, out);
    out.flush();
    readInt(in); // Client version, unused for now

    ServeCommand cmd = (ServeCommand) readInt(in);
    switch (cmd) {
        case cmdQuery:
            while (true) {
                QueryCommand qCmd;
                try {
                    qCmd = (QueryCommand) readInt(in);
                } catch (EndOfFile & e) {
                    break;
                }
                switch (qCmd) {
                    case qCmdHave: {
                        PathSet paths = readStrings<PathSet>(in);
                        writeStrings(store->queryValidPaths(paths), out);
                        break;
                    }
                    case qCmdInfo: {
                        PathSet paths = readStrings<PathSet>(in);
                        // !!! Maybe we want a queryPathInfos?
                        foreach (PathSet::iterator, i, paths) {
                            if (!store->isValidPath(*i))
                                continue;
                            ValidPathInfo info = store->queryPathInfo(*i);
                            writeString(info.path, out);
                            writeString(info.deriver, out);
                            writeStrings(info.references, out);
                            // !!! Maybe we want compression?
                            writeLongLong(info.narSize, out); // downloadSize
                            writeLongLong(info.narSize, out);
                        }
                        writeString("", out);
                        break;
                    }
                    default:
                        throw Error(format("unknown serve query `%1%'") % cmd);
                }
                out.flush();
            }
            break;
        case cmdSubstitute:
            dumpPath(readString(in), out);
            break;
        default:
            throw Error(format("unknown serve command `%1%'") % cmd);
    }
}


/* Scan the arguments; find the operation, set global flags, put all
   other flags in a list, and put all other arguments in another
   list. */
void run(Strings args)
{
    Strings opFlags, opArgs;
    Operation op = 0;

    for (Strings::iterator i = args.begin(); i != args.end(); ) {
        string arg = *i++;

        Operation oldOp = op;

        if (arg == "--realise" || arg == "--realize" || arg == "-r")
            op = opRealise;
        else if (arg == "--add" || arg == "-A")
            op = opAdd;
        else if (arg == "--add-fixed")
            op = opAddFixed;
        else if (arg == "--print-fixed-path")
            op = opPrintFixedPath;
        else if (arg == "--delete")
            op = opDelete;
        else if (arg == "--query" || arg == "-q")
            op = opQuery;
        else if (arg == "--print-env")
            op = opPrintEnv;
        else if (arg == "--read-log" || arg == "-l")
            op = opReadLog;
        else if (arg == "--dump-db")
            op = opDumpDB;
        else if (arg == "--load-db")
            op = opLoadDB;
        else if (arg == "--register-validity")
            op = opRegisterValidity;
        else if (arg == "--check-validity")
            op = opCheckValidity;
        else if (arg == "--gc")
            op = opGC;
        else if (arg == "--dump")
            op = opDump;
        else if (arg == "--restore")
            op = opRestore;
        else if (arg == "--export")
            op = opExport;
        else if (arg == "--import")
            op = opImport;
        else if (arg == "--init")
            op = opInit;
        else if (arg == "--verify")
            op = opVerify;
        else if (arg == "--verify-path")
            op = opVerifyPath;
        else if (arg == "--repair-path")
            op = opRepairPath;
        else if (arg == "--optimise" || arg == "--optimize")
            op = opOptimise;
        else if (arg == "--query-failed-paths")
            op = opQueryFailedPaths;
        else if (arg == "--clear-failed-paths")
            op = opClearFailedPaths;
        else if (arg == "--add-root") {
            if (i == args.end())
                throw UsageError("`--add-root requires an argument");
            gcRoot = absPath(*i++);
        }
        else if (arg == "--indirect")
            indirectRoot = true;
        else if (arg == "--no-output")
            noOutput = true;
        else if (arg == "--serve")
            op = opServe;
        else if (arg[0] == '-') {
            opFlags.push_back(arg);
            if (arg == "--max-freed" || arg == "--max-links" || arg == "--max-atime") { /* !!! hack */
                if (i != args.end()) opFlags.push_back(*i++);
            }
        }
        else
            opArgs.push_back(arg);

        if (oldOp && oldOp != op)
            throw UsageError("only one operation may be specified");
    }

    if (!op) throw UsageError("no operation specified");

    if (op != opDump && op != opRestore) /* !!! hack */
        store = openStore(op != opGC);

    op(opFlags, opArgs);
}


string programId = "nix-store";