summaryrefslogtreecommitdiffstats
path: root/js/src/shell/OSObject.cpp
blob: 68b1d100ba38f1209769d945bf04bef673feec07 (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
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

// OSObject.h - os object for exposing posix system calls in the JS shell

#include "shell/OSObject.h"

#include <errno.h>
#include <stdlib.h>
#ifdef XP_WIN
#include <direct.h>
#include <process.h>
#include <string.h>
#else
#include <sys/wait.h>
#include <unistd.h>
#endif

#include "jsapi.h"
// For JSFunctionSpecWithHelp
#include "jsfriendapi.h"
#include "jsobj.h"
#ifdef XP_WIN
# include "jswin.h"
#endif
#include "jswrapper.h"

#include "js/Conversions.h"
#include "shell/jsshell.h"
#include "vm/StringBuffer.h"
#include "vm/TypedArrayObject.h"

#include "jsobjinlines.h"

#ifdef XP_WIN
# define PATH_MAX (MAX_PATH > _MAX_DIR ? MAX_PATH : _MAX_DIR)
# define getcwd _getcwd
#else
# include <libgen.h>
#endif

using js::shell::RCFile;

static RCFile** gErrFilePtr = nullptr;
static RCFile** gOutFilePtr = nullptr;

namespace js {
namespace shell {

#ifdef XP_WIN
const char PathSeparator = '\\';
#else
const char PathSeparator = '/';
#endif

static bool
IsAbsolutePath(const JSAutoByteString& filename)
{
    const char* pathname = filename.ptr();

    if (pathname[0] == PathSeparator)
        return true;

#ifdef XP_WIN
    // On Windows there are various forms of absolute paths (see
    // http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx
    // for details):
    //
    //   "\..."
    //   "\\..."
    //   "C:\..."
    //
    // The first two cases are handled by the test above so we only need a test
    // for the last one here.

    if ((strlen(pathname) > 3 &&
        isalpha(pathname[0]) && pathname[1] == ':' && pathname[2] == '\\'))
    {
        return true;
    }
#endif

    return false;
}

/*
 * Resolve a (possibly) relative filename to an absolute path. If
 * |scriptRelative| is true, then the result will be relative to the directory
 * containing the currently-running script, or the current working directory if
 * the currently-running script is "-e" (namely, you're using it from the
 * command line.) Otherwise, it will be relative to the current working
 * directory.
 */
JSString*
ResolvePath(JSContext* cx, HandleString filenameStr, PathResolutionMode resolveMode)
{
    if (!filenameStr) {
#ifdef XP_WIN
        return JS_NewStringCopyZ(cx, "nul");
#else
        return JS_NewStringCopyZ(cx, "/dev/null");
#endif
    }

    JSAutoByteString filename(cx, filenameStr);
    if (!filename)
        return nullptr;

    if (IsAbsolutePath(filename))
        return filenameStr;

    /* Get the currently executing script's name. */
    JS::AutoFilename scriptFilename;
    if (!DescribeScriptedCaller(cx, &scriptFilename))
        return nullptr;

    if (!scriptFilename.get())
        return nullptr;

    if (strcmp(scriptFilename.get(), "-e") == 0 || strcmp(scriptFilename.get(), "typein") == 0)
        resolveMode = RootRelative;

    char buffer[PATH_MAX+1];
    if (resolveMode == ScriptRelative) {
#ifdef XP_WIN
        // The docs say it can return EINVAL, but the compiler says it's void
        _splitpath(scriptFilename.get(), nullptr, buffer, nullptr, nullptr);
#else
        strncpy(buffer, scriptFilename.get(), PATH_MAX+1);
        if (buffer[PATH_MAX] != '\0')
            return nullptr;

        // dirname(buffer) might return buffer, or it might return a
        // statically-allocated string
        memmove(buffer, dirname(buffer), strlen(buffer) + 1);
#endif
    } else {
        const char* cwd = getcwd(buffer, PATH_MAX);
        if (!cwd)
            return nullptr;
    }

    size_t len = strlen(buffer);
    buffer[len] = '/';
    strncpy(buffer + len + 1, filename.ptr(), sizeof(buffer) - (len+1));
    if (buffer[PATH_MAX] != '\0')
        return nullptr;

    return JS_NewStringCopyZ(cx, buffer);
}

JSObject*
FileAsTypedArray(JSContext* cx, JS::HandleString pathnameStr)
{
    JSAutoByteString pathname(cx, pathnameStr);
    if (!pathname)
        return nullptr;

    FILE* file = fopen(pathname.ptr(), "rb");
    if (!file) {
        /*
         * Use Latin1 variant here because the encoding of the return value of
         * strerror function can be non-UTF-8.
         */
        JS_ReportErrorLatin1(cx, "can't open %s: %s", pathname.ptr(), strerror(errno));
        return nullptr;
    }
    AutoCloseFile autoClose(file);

    RootedObject obj(cx);
    if (fseek(file, 0, SEEK_END) != 0) {
        pathname.clear();
        if (!pathname.encodeUtf8(cx, pathnameStr))
            return nullptr;
        JS_ReportErrorUTF8(cx, "can't seek end of %s", pathname.ptr());
    } else {
        size_t len = ftell(file);
        if (fseek(file, 0, SEEK_SET) != 0) {
            pathname.clear();
            if (!pathname.encodeUtf8(cx, pathnameStr))
                return nullptr;
            JS_ReportErrorUTF8(cx, "can't seek start of %s", pathname.ptr());
        } else {
            if (len > INT32_MAX) {
                JS_ReportErrorUTF8(cx, "file %s is too large for a Uint8Array",
                                   pathname.ptr());
                return nullptr;
            }        
            obj = JS_NewUint8Array(cx, len);
            if (!obj)
                return nullptr;
            js::TypedArrayObject& ta = obj->as<js::TypedArrayObject>();
            if (ta.isSharedMemory()) {
                // Must opt in to use shared memory.  For now, don't.
                //
                // (It is incorrect to read into the buffer without
                // synchronization since that can create a race.  A
                // lock here won't fix it - both sides must
                // participate.  So what one must do is to create a
                // temporary buffer, read into that, and use a
                // race-safe primitive to copy memory into the
                // buffer.)
                pathname.clear();
                if (!pathname.encodeUtf8(cx, pathnameStr))
                    return nullptr;
                JS_ReportErrorUTF8(cx, "can't read %s: shared memory buffer", pathname.ptr());
                return nullptr;
            }
            char* buf = static_cast<char*>(ta.viewDataUnshared());
            size_t cc = fread(buf, 1, len, file);
            if (cc != len) {
                if (ptrdiff_t(cc) < 0) {
                    /*
                     * Use Latin1 variant here because the encoding of the return
                     * value of strerror function can be non-UTF-8.
                     */
                    JS_ReportErrorLatin1(cx, "can't read %s: %s", pathname.ptr(), strerror(errno));
                } else {
                    pathname.clear();
                    if (!pathname.encodeUtf8(cx, pathnameStr))
                        return nullptr;
                    JS_ReportErrorUTF8(cx, "can't read %s: short read", pathname.ptr());
                }
                obj = nullptr;
            }
        }
    }
    return obj;
}

static bool
ReadFile(JSContext* cx, unsigned argc, Value* vp, bool scriptRelative)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1 || args.length() > 2) {
        JS_ReportErrorNumberASCII(cx, js::shell::my_GetErrorMessage, nullptr,
                                  args.length() < 1 ? JSSMSG_NOT_ENOUGH_ARGS : JSSMSG_TOO_MANY_ARGS,
                                  "snarf");
        return false;
    }

    if (!args[0].isString() || (args.length() == 2 && !args[1].isString())) {
        JS_ReportErrorNumberASCII(cx, js::shell::my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "snarf");
        return false;
    }

    RootedString givenPath(cx, args[0].toString());
    RootedString str(cx, js::shell::ResolvePath(cx, givenPath, scriptRelative ? ScriptRelative : RootRelative));
    if (!str)
        return false;

    if (args.length() > 1) {
        JSString* opt = JS::ToString(cx, args[1]);
        if (!opt)
            return false;
        bool match;
        if (!JS_StringEqualsAscii(cx, opt, "binary", &match))
            return false;
        if (match) {
            JSObject* obj;
            if (!(obj = FileAsTypedArray(cx, str)))
                return false;
            args.rval().setObject(*obj);
            return true;
        }
    }

    if (!(str = FileAsString(cx, str)))
        return false;
    args.rval().setString(str);
    return true;
}

static bool
osfile_readFile(JSContext* cx, unsigned argc, Value* vp)
{
    return ReadFile(cx, argc, vp, false);
}

static bool
osfile_readRelativeToScript(JSContext* cx, unsigned argc, Value* vp)
{
    return ReadFile(cx, argc, vp, true);
}

static bool
osfile_writeTypedArrayToFile(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 2 ||
        !args[0].isString() ||
        !args[1].isObject() ||
        !args[1].toObject().is<TypedArrayObject>())
    {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "writeTypedArrayToFile");
        return false;
    }

    RootedString givenPath(cx, args[0].toString());
    RootedString str(cx, ResolvePath(cx, givenPath, RootRelative));
    if (!str)
        return false;

    JSAutoByteString filename(cx, str);
    if (!filename)
        return false;

    FILE* file = fopen(filename.ptr(), "wb");
    if (!file) {
        /*
         * Use Latin1 variant here because the encoding of the return value of
         * strerror function can be non-UTF-8.
         */
        JS_ReportErrorLatin1(cx, "can't open %s: %s", filename.ptr(), strerror(errno));
        return false;
    }
    AutoCloseFile autoClose(file);

    TypedArrayObject* obj = &args[1].toObject().as<TypedArrayObject>();

    if (obj->isSharedMemory()) {
        // Must opt in to use shared memory.  For now, don't.
        //
        // See further comments in FileAsTypedArray, above.
        filename.clear();
        if (!filename.encodeUtf8(cx, str))
            return false;
        JS_ReportErrorUTF8(cx, "can't write %s: shared memory buffer", filename.ptr());
        return false;
    }
    void* buf = obj->viewDataUnshared();
    if (fwrite(buf, obj->bytesPerElement(), obj->length(), file) != obj->length() ||
        !autoClose.release())
    {
        filename.clear();
        if (!filename.encodeUtf8(cx, str))
            return false;
        JS_ReportErrorUTF8(cx, "can't write %s", filename.ptr());
        return false;
    }

    args.rval().setUndefined();
    return true;
}

/* static */ RCFile*
RCFile::create(JSContext* cx, const char* filename, const char* mode)
{
    FILE* fp = fopen(filename, mode);
    if (!fp)
        return nullptr;

    RCFile* file = cx->new_<RCFile>(fp);
    if (!file) {
        fclose(fp);
        return nullptr;
    }

    return file;
}

void
RCFile::close()
{
    if (fp)
        fclose(fp);
    fp = nullptr;
}

bool
RCFile::release()
{
    if (--numRefs)
        return false;
    this->close();
    return true;
}

class FileObject : public JSObject {
    enum : uint32_t {
        FILE_SLOT = 0,
        NUM_SLOTS
    };

  public:
    static const js::Class class_;

    static FileObject* create(JSContext* cx, RCFile* file) {
        JSObject* obj = js::NewObjectWithClassProto(cx, &class_, nullptr);
        if (!obj)
            return nullptr;

        FileObject* fileObj = &obj->as<FileObject>();
        fileObj->setRCFile(file);
        file->acquire();
        return fileObj;
    }

    static void finalize(FreeOp* fop, JSObject* obj) {
        FileObject* fileObj = &obj->as<FileObject>();
        RCFile* file = fileObj->rcFile();
        if (file->release()) {
            fileObj->setRCFile(nullptr);
            fop->delete_(file);
        }
    }

    bool isOpen() {
        RCFile* file = rcFile();
        return file && file->isOpen();
    }

    void close() {
        if (!isOpen())
            return;
        rcFile()->close();
    }

    RCFile* rcFile() {
        return reinterpret_cast<RCFile*>(js::GetReservedSlot(this, FILE_SLOT).toPrivate());
    }

  private:

    void setRCFile(RCFile* file) {
        js::SetReservedSlot(this, FILE_SLOT, PrivateValue(file));
    }
};

static const js::ClassOps FileObjectClassOps = {
    nullptr,               /* addProperty */
    nullptr,               /* delProperty */
    nullptr,               /* getProperty */
    nullptr,               /* setProperty */
    nullptr,               /* enumerate */
    nullptr,               /* resolve */
    nullptr,               /* mayResolve */
    FileObject::finalize,  /* finalize */
    nullptr,               /* call */
    nullptr,               /* hasInstance */
    nullptr,               /* construct */
    nullptr                /* trace */
};

const js::Class FileObject::class_ = {
    "File",
    JSCLASS_HAS_RESERVED_SLOTS(FileObject::NUM_SLOTS) |
    JSCLASS_FOREGROUND_FINALIZE,
    &FileObjectClassOps
};

static FileObject*
redirect(JSContext* cx, HandleString relFilename, RCFile** globalFile)
{
    RootedString filename(cx, ResolvePath(cx, relFilename, RootRelative));
    if (!filename)
        return nullptr;
    JSAutoByteString filenameABS(cx, filename);
    if (!filenameABS)
        return nullptr;
    RCFile* file = RCFile::create(cx, filenameABS.ptr(), "wb");
    if (!file) {
        /*
         * Use Latin1 variant here because the encoding of the return value of
         * strerror function can be non-UTF-8.
         */
        JS_ReportErrorLatin1(cx, "cannot redirect to %s: %s", filenameABS.ptr(), strerror(errno));
        return nullptr;
    }

    // Grant the global gOutFile ownership of the new file, release ownership
    // of its old file, and return a FileObject owning the old file.
    file->acquire(); // Global owner of new file

    FileObject* fileObj = FileObject::create(cx, *globalFile); // Newly created owner of old file
    if (!fileObj) {
        file->release();
        return nullptr;
    }

    (*globalFile)->release(); // Release (global) ownership of old file.
    *globalFile = file;

    return fileObj;
}

static bool
Redirect(JSContext* cx, const CallArgs& args, RCFile** outFile)
{
    if (args.length() > 1) {
        JS_ReportErrorNumberASCII(cx, js::shell::my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "redirect");
        return false;
    }

    RCFile* oldFile = *outFile;
    RootedObject oldFileObj(cx, FileObject::create(cx, oldFile));
    if (!oldFileObj)
        return false;

    if (args.get(0).isUndefined()) {
        args.rval().setObject(*oldFileObj);
        return true;
    }

    if (args[0].isObject()) {
        RootedObject fileObj(cx, js::CheckedUnwrap(&args[0].toObject()));
        if (!fileObj)
            return false;

        if (fileObj->is<FileObject>()) {
            // Passed in a FileObject. Create a FileObject for the previous
            // global file, and set the global file to the passed-in one.
            *outFile = fileObj->as<FileObject>().rcFile();
            (*outFile)->acquire();
            oldFile->release();

            args.rval().setObject(*oldFileObj);
            return true;
        }
    }

    RootedString filename(cx);
    if (!args[0].isNull()) {
        filename = JS::ToString(cx, args[0]);
        if (!filename)
            return false;
    }

    if (!redirect(cx, filename, outFile))
        return false;

    args.rval().setObject(*oldFileObj);
    return true;
}

static bool
osfile_redirectOutput(JSContext* cx, unsigned argc, Value* vp) {
    CallArgs args = CallArgsFromVp(argc, vp);
    return Redirect(cx, args, gOutFilePtr);
}

static bool
osfile_redirectError(JSContext* cx, unsigned argc, Value* vp) {
    CallArgs args = CallArgsFromVp(argc, vp);
    return Redirect(cx, args, gErrFilePtr);
}

static bool
osfile_close(JSContext* cx, unsigned argc, Value* vp) {
    CallArgs args = CallArgsFromVp(argc, vp);

    Rooted<FileObject*> fileObj(cx);
    if (args.get(0).isObject()) {
        JSObject *obj = js::CheckedUnwrap(&args[0].toObject());
        if (obj->is<FileObject>())
            fileObj = &obj->as<FileObject>();
    }

    if (!fileObj) {
        JS_ReportErrorNumberASCII(cx, js::shell::my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "close");
        return false;
    }

    fileObj->close();

    args.rval().setUndefined();
    return true;
}

static const JSFunctionSpecWithHelp osfile_functions[] = {
    JS_FN_HELP("readFile", osfile_readFile, 1, 0,
"readFile(filename, [\"binary\"])",
"  Read filename into returned string. Filename is relative to the current\n"
               "  working directory."),

    JS_FN_HELP("readRelativeToScript", osfile_readRelativeToScript, 1, 0,
"readRelativeToScript(filename, [\"binary\"])",
"  Read filename into returned string. Filename is relative to the directory\n"
"  containing the current script."),

    JS_FS_HELP_END
};

static const JSFunctionSpecWithHelp osfile_unsafe_functions[] = {
    JS_FN_HELP("writeTypedArrayToFile", osfile_writeTypedArrayToFile, 2, 0,
"writeTypedArrayToFile(filename, data)",
"  Write the contents of a typed array to the named file."),

    JS_FN_HELP("redirect", osfile_redirectOutput, 1, 0,
"redirect([path-or-object])",
"  Redirect print() output to the named file.\n"
"   Return an opaque object representing the previous destination, which\n"
"   may be passed into redirect() later to restore the output."),

    JS_FN_HELP("redirectErr", osfile_redirectError, 1, 0,
"redirectErr([path-or-object])",
"  Same as redirect(), but for printErr"),

    JS_FN_HELP("close", osfile_close, 1, 0,
"close(object)",
"  Close the file returned by an earlier redirect call."),

    JS_FS_HELP_END
};

static bool
ospath_isAbsolute(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() != 1 || !args[0].isString()) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS,
                                  "isAbsolute");
        return false;
    }

    JSAutoByteString path(cx, args[0].toString());
    if (!path)
        return false;

    args.rval().setBoolean(IsAbsolutePath(path));
    return true;
}

static bool
ospath_join(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() < 1) {
        JS_ReportErrorNumberASCII(cx, my_GetErrorMessage, nullptr, JSSMSG_INVALID_ARGS, "join");
        return false;
    }

    // This function doesn't take into account some aspects of Windows paths,
    // e.g. the drive letter is always reset when an absolute path is appended.

    StringBuffer buffer(cx);

    for (unsigned i = 0; i < args.length(); i++) {
        if (!args[i].isString()) {
            JS_ReportErrorASCII(cx, "join expects string arguments only");
            return false;
        }

        JSAutoByteString path(cx, args[i].toString());
        if (!path)
            return false;

        if (IsAbsolutePath(path)) {
            MOZ_ALWAYS_TRUE(buffer.resize(0));
        } else if (i != 0) {
            if (!buffer.append(PathSeparator))
                return false;
        }

        if (!buffer.append(args[i].toString()))
            return false;
    }

    JSString* result = buffer.finishString();
    if (!result)
        return false;

    args.rval().setString(result);
    return true;
}

static const JSFunctionSpecWithHelp ospath_functions[] = {
    JS_FN_HELP("isAbsolute", ospath_isAbsolute, 1, 0,
"isAbsolute(path)",
"  Return whether the given path is absolute."),

    JS_FN_HELP("join", ospath_join, 1, 0,
"join(paths...)",
"  Join one or more path components in a platform independent way."),

    JS_FS_HELP_END
};

static bool
os_getenv(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() < 1) {
        JS_ReportErrorASCII(cx, "os.getenv requires 1 argument");
        return false;
    }
    RootedString key(cx, ToString(cx, args[0]));
    if (!key)
        return false;
    JSAutoByteString keyBytes;
    if (!keyBytes.encodeUtf8(cx, key))
        return false;

    if (const char* valueBytes = getenv(keyBytes.ptr())) {
        RootedString value(cx, JS_NewStringCopyZ(cx, valueBytes));
        if (!value)
            return false;
        args.rval().setString(value);
    } else {
        args.rval().setUndefined();
    }
    return true;
}

static bool
os_getpid(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    if (args.length() != 0) {
        JS_ReportErrorASCII(cx, "os.getpid takes no arguments");
        return false;
    }
    args.rval().setInt32(getpid());
    return true;
}

#if !defined(XP_WIN)

// There are two possible definitions of strerror_r floating around. The GNU
// one returns a char* which may or may not be the buffer you passed in. The
// other one returns an integer status code, and always writes the result into
// the provided buffer.

inline char*
strerror_message(int result, char* buffer)
{
    return result == 0 ? buffer : nullptr;
}

inline char*
strerror_message(char* result, char* buffer)
{
    return result;
}

#endif

static void
ReportSysError(JSContext* cx, const char* prefix)
{
    char buffer[200];

#if defined(XP_WIN)
    strerror_s(buffer, sizeof(buffer), errno);
    const char* errstr = buffer;
#else
    const char* errstr = strerror_message(strerror_r(errno, buffer, sizeof(buffer)), buffer);
#endif

    if (!errstr)
        errstr = "unknown error";

    size_t nbytes = strlen(prefix) + strlen(errstr) + 3;
    char* final = (char*) js_malloc(nbytes);
    if (!final) {
        JS_ReportOutOfMemory(cx);
        return;
    }

    snprintf(final, nbytes, "%s: %s", prefix, errstr);
    /*
     * Use Latin1 variant here because the encoding of the return value of
     * strerror_s and strerror_r function can be non-UTF-8.
     */
    JS_ReportErrorLatin1(cx, "%s", final);
    js_free(final);
}

static bool
os_system(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() == 0) {
        JS_ReportErrorASCII(cx, "os.system requires 1 argument");
        return false;
    }

    JSString* str = JS::ToString(cx, args[0]);
    if (!str)
        return false;

    JSAutoByteString command(cx, str);
    if (!command)
        return false;

    int result = system(command.ptr());
    if (result == -1) {
        ReportSysError(cx, "system call failed");
        return false;
    }

    args.rval().setInt32(result);
    return true;
}

#ifndef XP_WIN
static bool
os_spawn(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    if (args.length() == 0) {
        JS_ReportErrorASCII(cx, "os.spawn requires 1 argument");
        return false;
    }

    JSString* str = JS::ToString(cx, args[0]);
    if (!str)
        return false;

    JSAutoByteString command(cx, str);
    if (!command)
        return false;

    int32_t childPid = fork();
    if (childPid == -1) {
        ReportSysError(cx, "fork failed");
        return false;
    }

    if (childPid) {
        args.rval().setInt32(childPid);
        return true;
    }

    // We are in the child

    const char* cmd[] = {"sh", "-c", nullptr, nullptr};
    cmd[2] = command.ptr();

    execvp("sh", (char * const*)cmd);
    exit(1);
}

static bool
os_kill(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    int32_t pid;
    if (args.length() < 1) {
        JS_ReportErrorASCII(cx, "os.kill requires 1 argument");
        return false;
    }
    if (!JS::ToInt32(cx, args[0], &pid))
        return false;

    // It is too easy to kill yourself accidentally with os.kill("goose").
    if (pid == 0 && !args[0].isInt32()) {
        JS_ReportErrorASCII(cx, "os.kill requires numeric pid");
        return false;
    }

    int signal = SIGINT;
    if (args.length() > 1) {
        if (!JS::ToInt32(cx, args[1], &signal))
            return false;
    }

    int status = kill(pid, signal);
    if (status == -1) {
        ReportSysError(cx, "kill failed");
        return false;
    }

    args.rval().setUndefined();
    return true;
}

static bool
os_waitpid(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    int32_t pid;
    if (args.length() == 0) {
        pid = -1;
    } else {
        if (!JS::ToInt32(cx, args[0], &pid))
            return false;
    }

    bool nohang = false;
    if (args.length() >= 2)
        nohang = JS::ToBoolean(args[1]);

    int status = 0;
    pid_t result = waitpid(pid, &status, nohang ? WNOHANG : 0);
    if (result == -1) {
        ReportSysError(cx, "os.waitpid failed");
        return false;
    }

    RootedObject info(cx, JS_NewPlainObject(cx));
    if (!info)
        return false;

    RootedValue v(cx);
    if (result != 0) {
        v.setInt32(result);
        if (!JS_DefineProperty(cx, info, "pid", v, JSPROP_ENUMERATE))
            return false;
        if (WIFEXITED(status)) {
            v.setInt32(WEXITSTATUS(status));
            if (!JS_DefineProperty(cx, info, "exitStatus", v, JSPROP_ENUMERATE))
                return false;
        }
    }

    args.rval().setObject(*info);
    return true;
}
#endif

static const JSFunctionSpecWithHelp os_functions[] = {
    JS_FN_HELP("getenv", os_getenv, 1, 0,
"getenv(variable)",
"  Get the value of an environment variable."),

    JS_FN_HELP("getpid", os_getpid, 0, 0,
"getpid()",
"  Return the current process id."),

    JS_FN_HELP("system", os_system, 1, 0,
"system(command)",
"  Execute command on the current host, returning result code or throwing an\n"
"  exception on failure."),

#ifndef XP_WIN
    JS_FN_HELP("spawn", os_spawn, 1, 0,
"spawn(command)",
"  Start up a separate process running the given command. Returns the pid."),

    JS_FN_HELP("kill", os_kill, 1, 0,
"kill(pid[, signal])",
"  Send a signal to the given pid. The default signal is SIGINT. The signal\n"
"  passed in must be numeric, if given."),

    JS_FN_HELP("waitpid", os_waitpid, 1, 0,
"waitpid(pid[, nohang])",
"  Calls waitpid(). 'nohang' is a boolean indicating whether to pass WNOHANG.\n"
"  The return value is an object containing a 'pid' field, if a process was waitable\n"
"  and an 'exitStatus' field if a pid exited."),
#endif

    JS_FS_HELP_END
};

bool
DefineOS(JSContext* cx, HandleObject global,
         bool fuzzingSafe,
         RCFile** shellOut, RCFile** shellErr)
{
    RootedObject obj(cx, JS_NewPlainObject(cx));
    if (!obj || !JS_DefineProperty(cx, global, "os", obj, 0))
        return false;

    if (!fuzzingSafe) {
        if (!JS_DefineFunctionsWithHelp(cx, obj, os_functions))
            return false;
    }

    RootedObject osfile(cx, JS_NewPlainObject(cx));
    if (!osfile ||
        !JS_DefineFunctionsWithHelp(cx, osfile, osfile_functions) ||
        !JS_DefineProperty(cx, obj, "file", osfile, 0))
    {
        return false;
    }

    if (!fuzzingSafe) {
        if (!JS_DefineFunctionsWithHelp(cx, osfile, osfile_unsafe_functions))
            return false;
    }

    if (!GenerateInterfaceHelp(cx, osfile, "os.file"))
        return false;

    RootedObject ospath(cx, JS_NewPlainObject(cx));
    if (!ospath ||
        !JS_DefineFunctionsWithHelp(cx, ospath, ospath_functions) ||
        !JS_DefineProperty(cx, obj, "path", ospath, 0) ||
        !GenerateInterfaceHelp(cx, ospath, "os.path"))
    {
        return false;
    }

    if (!GenerateInterfaceHelp(cx, obj, "os"))
        return false;

    gOutFilePtr = shellOut;
    gErrFilePtr = shellErr;

    // For backwards compatibility, expose various os.file.* functions as
    // direct methods on the global.
    RootedValue val(cx);

    struct {
        const char* src;
        const char* dst;
    } osfile_exports[] = {
        { "readFile", "read" },
        { "readFile", "snarf" },
        { "readRelativeToScript", "readRelativeToScript" },
        { "redirect", "redirect" },
        { "redirectErr", "redirectErr" }
    };

    for (auto pair : osfile_exports) {
        if (!JS_GetProperty(cx, osfile, pair.src, &val))
            return false;
        if (val.isObject()) {
            RootedObject function(cx, &val.toObject());
            if (!JS_DefineProperty(cx, global, pair.dst, function, 0))
                return false;
        }
    }

    return true;
}

} // namespace shell
} // namespace js