summaryrefslogtreecommitdiffstats
path: root/xpcom/glue/FileUtils.cpp
blob: 53fe687080b2bc84d8d83ab5bdd69ee626ec8d04 (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
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#include <errno.h>
#include <stdio.h>

#include "nscore.h"
#include "nsStringGlue.h"
#include "private/pprio.h"
#include "mozilla/Assertions.h"
#include "mozilla/FileUtils.h"

#if defined(XP_MACOSX)
#include <fcntl.h>
#include <unistd.h>
#include <mach/machine.h>
#include <mach-o/fat.h>
#include <mach-o/loader.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <limits.h>
#elif defined(XP_UNIX)
#include <fcntl.h>
#include <unistd.h>
#if defined(LINUX)
#include <elf.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#elif defined(XP_WIN)
#include <windows.h>
#endif

// Functions that are not to be used in standalone glue must be implemented
// within this #if block
#if !defined(XPCOM_GLUE)

bool
mozilla::fallocate(PRFileDesc* aFD, int64_t aLength)
{
#if defined(HAVE_POSIX_FALLOCATE)
  return posix_fallocate(PR_FileDesc2NativeHandle(aFD), 0, aLength) == 0;
#elif defined(XP_WIN)
  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
  if (oldpos == -1) {
    return false;
  }

  if (PR_Seek64(aFD, aLength, PR_SEEK_SET) != aLength) {
    return false;
  }

  bool retval = (0 != SetEndOfFile((HANDLE)PR_FileDesc2NativeHandle(aFD)));

  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
  return retval;
#elif defined(XP_MACOSX)
  int fd = PR_FileDesc2NativeHandle(aFD);
  fstore_t store = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, aLength};
  // Try to get a continous chunk of disk space
  int ret = fcntl(fd, F_PREALLOCATE, &store);
  if (ret == -1) {
    // OK, perhaps we are too fragmented, allocate non-continuous
    store.fst_flags = F_ALLOCATEALL;
    ret = fcntl(fd, F_PREALLOCATE, &store);
    if (ret == -1) {
      return false;
    }
  }
  return ftruncate(fd, aLength) == 0;
#elif defined(XP_UNIX)
  // The following is copied from fcntlSizeHint in sqlite
  /* If the OS does not have posix_fallocate(), fake it. First use
  ** ftruncate() to set the file size, then write a single byte to
  ** the last byte in each block within the extended region. This
  ** is the same technique used by glibc to implement posix_fallocate()
  ** on systems that do not have a real fallocate() system call.
  */
  int64_t oldpos = PR_Seek64(aFD, 0, PR_SEEK_CUR);
  if (oldpos == -1) {
    return false;
  }

  struct stat buf;
  int fd = PR_FileDesc2NativeHandle(aFD);
  if (fstat(fd, &buf)) {
    return false;
  }

  if (buf.st_size >= aLength) {
    return false;
  }

  const int nBlk = buf.st_blksize;

  if (!nBlk) {
    return false;
  }

  if (ftruncate(fd, aLength)) {
    return false;
  }

  int nWrite; // Return value from write()
  int64_t iWrite = ((buf.st_size + 2 * nBlk - 1) / nBlk) * nBlk - 1; // Next offset to write to
  while (iWrite < aLength) {
    nWrite = 0;
    if (PR_Seek64(aFD, iWrite, PR_SEEK_SET) == iWrite) {
      nWrite = PR_Write(aFD, "", 1);
    }
    if (nWrite != 1) {
      break;
    }
    iWrite += nBlk;
  }

  PR_Seek64(aFD, oldpos, PR_SEEK_SET);
  return nWrite == 1;
#endif
  return false;
}

#ifdef ReadSysFile_PRESENT

bool
mozilla::ReadSysFile(
  const char* aFilename,
  char* aBuf,
  size_t aBufSize)
{
  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_RDONLY));
  if (fd < 0) {
    return false;
  }
  ScopedClose autoClose(fd);
  if (aBufSize == 0) {
    return true;
  }
  ssize_t bytesRead;
  size_t offset = 0;
  do {
    bytesRead = MOZ_TEMP_FAILURE_RETRY(read(fd, aBuf + offset,
                                            aBufSize - offset));
    if (bytesRead == -1) {
      return false;
    }
    offset += bytesRead;
  } while (bytesRead > 0 && offset < aBufSize);
  MOZ_ASSERT(offset <= aBufSize);
  if (offset > 0 && aBuf[offset - 1] == '\n') {
    offset--;
  }
  if (offset == aBufSize) {
    MOZ_ASSERT(offset > 0);
    offset--;
  }
  aBuf[offset] = '\0';
  return true;
}

bool
mozilla::ReadSysFile(
  const char* aFilename,
  int* aVal)
{
  char valBuf[32];
  if (!ReadSysFile(aFilename, valBuf, sizeof(valBuf))) {
    return false;
  }
  return sscanf(valBuf, "%d", aVal) == 1;
}

bool
mozilla::ReadSysFile(
  const char* aFilename,
  bool* aVal)
{
  int v;
  if (!ReadSysFile(aFilename, &v)) {
    return false;
  }
  *aVal = (v != 0);
  return true;
}

#endif /* ReadSysFile_PRESENT */

#ifdef WriteSysFile_PRESENT

bool
mozilla::WriteSysFile(
  const char* aFilename,
  const char* aBuf)
{
  size_t aBufSize = strlen(aBuf);
  int fd = MOZ_TEMP_FAILURE_RETRY(open(aFilename, O_WRONLY));
  if (fd < 0) {
    return false;
  }
  ScopedClose autoClose(fd);
  ssize_t bytesWritten;
  size_t offset = 0;
  do {
    bytesWritten = MOZ_TEMP_FAILURE_RETRY(write(fd, aBuf + offset,
                                                aBufSize - offset));
    if (bytesWritten == -1) {
      return false;
    }
    offset += bytesWritten;
  } while (bytesWritten > 0 && offset < aBufSize);
  MOZ_ASSERT(offset == aBufSize);
  return true;
}

#endif /* WriteSysFile_PRESENT */

void
mozilla::ReadAheadLib(nsIFile* aFile)
{
#if defined(XP_WIN)
  nsAutoString path;
  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
    return;
  }
  ReadAheadLib(path.get());
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
  nsAutoCString nativePath;
  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
    return;
  }
  ReadAheadLib(nativePath.get());
#endif
}

void
mozilla::ReadAheadFile(nsIFile* aFile, const size_t aOffset,
                       const size_t aCount, mozilla::filedesc_t* aOutFd)
{
#if defined(XP_WIN)
  nsAutoString path;
  if (!aFile || NS_FAILED(aFile->GetPath(path))) {
    return;
  }
  ReadAheadFile(path.get(), aOffset, aCount, aOutFd);
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX)
  nsAutoCString nativePath;
  if (!aFile || NS_FAILED(aFile->GetNativePath(nativePath))) {
    return;
  }
  ReadAheadFile(nativePath.get(), aOffset, aCount, aOutFd);
#endif
}

#endif // !defined(XPCOM_GLUE)

#if defined(LINUX) && !defined(ANDROID)

static const unsigned int bufsize = 4096;

#ifdef __LP64__
typedef Elf64_Ehdr Elf_Ehdr;
typedef Elf64_Phdr Elf_Phdr;
static const unsigned char ELFCLASS = ELFCLASS64;
typedef Elf64_Off Elf_Off;
#else
typedef Elf32_Ehdr Elf_Ehdr;
typedef Elf32_Phdr Elf_Phdr;
static const unsigned char ELFCLASS = ELFCLASS32;
typedef Elf32_Off Elf_Off;
#endif

#elif defined(XP_MACOSX)

#if defined(__i386__)
static const uint32_t CPU_TYPE = CPU_TYPE_X86;
#elif defined(__x86_64__)
static const uint32_t CPU_TYPE = CPU_TYPE_X86_64;
#elif defined(__ppc__)
static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC;
#elif defined(__ppc64__)
static const uint32_t CPU_TYPE = CPU_TYPE_POWERPC64;
#else
#error Unsupported CPU type
#endif

#ifdef __LP64__
#undef LC_SEGMENT
#define LC_SEGMENT LC_SEGMENT_64
#undef MH_MAGIC
#define MH_MAGIC MH_MAGIC_64
#define cpu_mach_header mach_header_64
#define segment_command segment_command_64
#else
#define cpu_mach_header mach_header
#endif

class ScopedMMap
{
public:
  explicit ScopedMMap(const char* aFilePath)
    : buf(nullptr)
  {
    fd = open(aFilePath, O_RDONLY);
    if (fd < 0) {
      return;
    }
    struct stat st;
    if (fstat(fd, &st) < 0) {
      return;
    }
    size = st.st_size;
    buf = (char*)mmap(nullptr, size, PROT_READ, MAP_PRIVATE, fd, 0);
  }
  ~ScopedMMap()
  {
    if (buf) {
      munmap(buf, size);
    }
    if (fd >= 0) {
      close(fd);
    }
  }
  operator char*() { return buf; }
  int getFd() { return fd; }
private:
  int fd;
  char* buf;
  size_t size;
};
#endif

void
mozilla::ReadAhead(mozilla::filedesc_t aFd, const size_t aOffset,
                   const size_t aCount)
{
#if defined(XP_WIN)

  LARGE_INTEGER fpOriginal;
  LARGE_INTEGER fpOffset;
#if defined(HAVE_LONG_LONG)
  fpOffset.QuadPart = 0;
#else
  fpOffset.u.LowPart = 0;
  fpOffset.u.HighPart = 0;
#endif

  // Get the current file pointer so that we can restore it. This isn't
  // really necessary other than to provide the same semantics regarding the
  // file pointer that other platforms do
  if (!SetFilePointerEx(aFd, fpOffset, &fpOriginal, FILE_CURRENT)) {
    return;
  }

  if (aOffset) {
#if defined(HAVE_LONG_LONG)
    fpOffset.QuadPart = static_cast<LONGLONG>(aOffset);
#else
    fpOffset.u.LowPart = aOffset;
    fpOffset.u.HighPart = 0;
#endif

    if (!SetFilePointerEx(aFd, fpOffset, nullptr, FILE_BEGIN)) {
      return;
    }
  }

  char buf[64 * 1024];
  size_t totalBytesRead = 0;
  DWORD dwBytesRead;
  // Do dummy reads to trigger kernel-side readhead via FILE_FLAG_SEQUENTIAL_SCAN.
  // Abort when underfilling because during testing the buffers are read fully
  // A buffer that's not keeping up would imply that readahead isn't working right
  while (totalBytesRead < aCount &&
         ReadFile(aFd, buf, sizeof(buf), &dwBytesRead, nullptr) &&
         dwBytesRead == sizeof(buf)) {
    totalBytesRead += dwBytesRead;
  }

  // Restore the file pointer
  SetFilePointerEx(aFd, fpOriginal, nullptr, FILE_BEGIN);

#elif defined(LINUX) && !defined(ANDROID)

  readahead(aFd, aOffset, aCount);

#elif defined(XP_MACOSX)

  struct radvisory ra;
  ra.ra_offset = aOffset;
  ra.ra_count = aCount;
  // The F_RDADVISE fcntl is equivalent to Linux' readahead() system call.
  fcntl(aFd, F_RDADVISE, &ra);

#endif
}

void
mozilla::ReadAheadLib(mozilla::pathstr_t aFilePath)
{
  if (!aFilePath) {
    return;
  }
#if defined(XP_WIN)
  ReadAheadFile(aFilePath);
#elif defined(LINUX) && !defined(ANDROID)
  int fd = open(aFilePath, O_RDONLY);
  if (fd < 0) {
    return;
  }

  union
  {
    char buf[bufsize];
    Elf_Ehdr ehdr;
  } elf;
  // Read ELF header (ehdr) and program header table (phdr).
  // We check that the ELF magic is found, that the ELF class matches
  // our own, and that the program header table as defined in the ELF
  // headers fits in the buffer we read.
  if ((read(fd, elf.buf, bufsize) <= 0) ||
      (memcmp(elf.buf, ELFMAG, 4)) ||
      (elf.ehdr.e_ident[EI_CLASS] != ELFCLASS) ||
      // Upcast e_phentsize so the multiplication is done in the same precision
      // as the subsequent addition, to satisfy static analyzers and avoid
      // issues with abnormally large program header tables.
      (elf.ehdr.e_phoff + (static_cast<Elf_Off>(elf.ehdr.e_phentsize) *
                           elf.ehdr.e_phnum) >= bufsize)) {
    close(fd);
    return;
  }
  // The program header table contains segment definitions. One such
  // segment type is PT_LOAD, which describes how the dynamic loader
  // is going to map the file in memory. We use that information to
  // find the biggest offset from the library that will be mapped in
  // memory.
  Elf_Phdr* phdr = (Elf_Phdr*)&elf.buf[elf.ehdr.e_phoff];
  Elf_Off end = 0;
  for (int phnum = elf.ehdr.e_phnum; phnum; phdr++, phnum--) {
    if ((phdr->p_type == PT_LOAD) &&
        (end < phdr->p_offset + phdr->p_filesz)) {
      end = phdr->p_offset + phdr->p_filesz;
    }
  }
  // Let the kernel read ahead what the dynamic loader is going to
  // map in memory soon after.
  if (end > 0) {
    ReadAhead(fd, 0, end);
  }
  close(fd);
#elif defined(XP_MACOSX)
  ScopedMMap buf(aFilePath);
  char* base = buf;
  if (!base) {
    return;
  }

  // An OSX binary might either be a fat (universal) binary or a
  // Mach-O binary. A fat binary actually embeds several Mach-O
  // binaries. If we have a fat binary, find the offset where the
  // Mach-O binary for our CPU type can be found.
  struct fat_header* fh = (struct fat_header*)base;

  if (OSSwapBigToHostInt32(fh->magic) == FAT_MAGIC) {
    uint32_t nfat_arch = OSSwapBigToHostInt32(fh->nfat_arch);
    struct fat_arch* arch = (struct fat_arch*)&buf[sizeof(struct fat_header)];
    for (; nfat_arch; arch++, nfat_arch--) {
      if (OSSwapBigToHostInt32(arch->cputype) == CPU_TYPE) {
        base += OSSwapBigToHostInt32(arch->offset);
        break;
      }
    }
    if (base == buf) {
      return;
    }
  }

  // Check Mach-O magic in the Mach header
  struct cpu_mach_header* mh = (struct cpu_mach_header*)base;
  if (mh->magic != MH_MAGIC) {
    return;
  }

  // The Mach header is followed by a sequence of load commands.
  // Each command has a header containing the command type and the
  // command size. LD_SEGMENT commands describes how the dynamic
  // loader is going to map the file in memory. We use that
  // information to find the biggest offset from the library that
  // will be mapped in memory.
  char* cmd = &base[sizeof(struct cpu_mach_header)];
  uint32_t end = 0;
  for (uint32_t ncmds = mh->ncmds; ncmds; ncmds--) {
    struct segment_command* sh = (struct segment_command*)cmd;
    if (sh->cmd != LC_SEGMENT) {
      continue;
    }
    if (end < sh->fileoff + sh->filesize) {
      end = sh->fileoff + sh->filesize;
    }
    cmd += sh->cmdsize;
  }
  // Let the kernel read ahead what the dynamic loader is going to
  // map in memory soon after.
  if (end > 0) {
    ReadAhead(buf.getFd(), base - buf, end);
  }
#endif
}

void
mozilla::ReadAheadFile(mozilla::pathstr_t aFilePath, const size_t aOffset,
                       const size_t aCount, mozilla::filedesc_t* aOutFd)
{
#if defined(XP_WIN)
  if (!aFilePath) {
    if (aOutFd) {
      *aOutFd = INVALID_HANDLE_VALUE;
    }
    return;
  }
  HANDLE fd = CreateFileW(aFilePath, GENERIC_READ, FILE_SHARE_READ, nullptr,
                          OPEN_EXISTING, FILE_FLAG_SEQUENTIAL_SCAN, nullptr);
  if (aOutFd) {
    *aOutFd = fd;
  }
  if (fd == INVALID_HANDLE_VALUE) {
    return;
  }
  ReadAhead(fd, aOffset, aCount);
  if (!aOutFd) {
    CloseHandle(fd);
  }
#elif defined(LINUX) && !defined(ANDROID) || defined(XP_MACOSX) || defined(XP_SOLARIS)
  if (!aFilePath) {
    if (aOutFd) {
      *aOutFd = -1;
    }
    return;
  }
  int fd = open(aFilePath, O_RDONLY);
  if (aOutFd) {
    *aOutFd = fd;
  }
  if (fd < 0) {
    return;
  }
  size_t count;
  if (aCount == SIZE_MAX) {
    struct stat st;
    if (fstat(fd, &st) < 0) {
      if (!aOutFd) {
        close(fd);
      }
      return;
    }
    count = st.st_size;
  } else {
    count = aCount;
  }
  ReadAhead(fd, aOffset, count);
  if (!aOutFd) {
    close(fd);
  }
#endif
}