DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Header

Mercurial (50bba836b642)

VCS Links

Line Code
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
/* 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 <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <cstdlib>
#include <algorithm>
#include "Logging.h"
#include "Zip.h"

already_AddRefed<Zip> Zip::Create(const char* filename) {
  /* Open and map the file in memory */
  AutoCloseFD fd(open(filename, O_RDONLY));
  if (fd == -1) {
    ERROR("Error opening %s: %s", filename, strerror(errno));
    return nullptr;
  }
  struct stat st;
  if (fstat(fd, &st) == -1) {
    ERROR("Error stating %s: %s", filename, strerror(errno));
    return nullptr;
  }
  size_t size = st.st_size;
  if (size <= sizeof(CentralDirectoryEnd)) {
    ERROR("Error reading %s: too short", filename);
    return nullptr;
  }
  void* mapped = mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0);
  if (mapped == MAP_FAILED) {
    ERROR("Error mmapping %s: %s", filename, strerror(errno));
    return nullptr;
  }
  DEBUG_LOG("Mapped %s @%p", filename, mapped);

  return Create(filename, mapped, size);
}

already_AddRefed<Zip> Zip::Create(const char* filename, void* mapped,
                                  size_t size) {
  RefPtr<Zip> zip = new Zip(filename, mapped, size);

  // If neither the first Local File entry nor central directory entries
  // have been found, the zip was invalid.
  if (!zip->nextFile && !zip->entries) {
    ERROR("%s - Invalid zip", filename);
    return nullptr;
  }

  ZipCollection::Singleton.Register(zip);
  return zip.forget();
}

Zip::Zip(const char* filename, void* mapped, size_t size)
    : name(filename ? strdup(filename) : nullptr),
      mapped(mapped),
      size(size),
      nextFile(LocalFile::validate(mapped))  // first Local File entry
      ,
      nextDir(nullptr),
      entries(nullptr) {
  pthread_mutex_init(&mutex, nullptr);
  // If the first local file entry couldn't be found (which can happen
  // with optimized jars), check the first central directory entry.
  if (!nextFile) GetFirstEntry();
}

Zip::~Zip() {
  if (name) {
    munmap(mapped, size);
    DEBUG_LOG("Unmapped %s @%p", name, mapped);
    free(name);
  }
  pthread_mutex_destroy(&mutex);
}

bool Zip::GetStream(const char* path, Zip::Stream* out) const {
  AutoLock lock(&mutex);

  DEBUG_LOG("%s - GetFile %s", name, path);
  /* Fast path: if the Local File header on store matches, we can return the
   * corresponding stream right away.
   * However, the Local File header may not contain enough information, in
   * which case the 3rd bit on the generalFlag is set. Unfortunately, this
   * bit is also set in some archives even when we do have the data (most
   * notably the android packages as built by the Mozilla build system).
   * So instead of testing the generalFlag bit, only use the fast path when
   * we haven't read the central directory entries yet, and when the
   * compressed size as defined in the header is not filled (which is a
   * normal condition for the bit to be set). */
  if (nextFile && nextFile->GetName().Equals(path) && !entries &&
      (nextFile->compressedSize != 0)) {
    DEBUG_LOG("%s - %s was next file: fast path", name, path);
    /* Fill Stream info from Local File header content */
    const char* data = reinterpret_cast<const char*>(nextFile->GetData());
    out->compressedBuf = data;
    out->compressedSize = nextFile->compressedSize;
    out->uncompressedSize = nextFile->uncompressedSize;
    out->CRC32 = nextFile->CRC32;
    out->type = static_cast<Stream::Type>(uint16_t(nextFile->compression));

    /* Find the next Local File header. It is usually simply following the
     * compressed stream, but in cases where the 3rd bit of the generalFlag
     * is set, there is a Data Descriptor header before. */
    data += nextFile->compressedSize;
    if ((nextFile->generalFlag & 0x8) && DataDescriptor::validate(data)) {
      data += sizeof(DataDescriptor);
    }
    nextFile = LocalFile::validate(data);
    return true;
  }

  /* If the directory entry we have in store doesn't match, scan the Central
   * Directory for the entry corresponding to the given path */
  if (!nextDir || !nextDir->GetName().Equals(path)) {
    const DirectoryEntry* entry = GetFirstEntry();
    DEBUG_LOG("%s - Scan directory entries in search for %s", name, path);
    while (entry && !entry->GetName().Equals(path)) {
      entry = entry->GetNext();
    }
    nextDir = entry;
  }
  if (!nextDir) {
    DEBUG_LOG("%s - Couldn't find %s", name, path);
    return false;
  }

  /* Find the Local File header corresponding to the Directory entry that
   * was found. */
  nextFile =
      LocalFile::validate(static_cast<const char*>(mapped) + nextDir->offset);
  if (!nextFile) {
    ERROR("%s - Couldn't find the Local File header for %s", name, path);
    return false;
  }

  /* Fill Stream info from Directory entry content */
  const char* data = reinterpret_cast<const char*>(nextFile->GetData());
  out->compressedBuf = data;
  out->compressedSize = nextDir->compressedSize;
  out->uncompressedSize = nextDir->uncompressedSize;
  out->CRC32 = nextDir->CRC32;
  out->type = static_cast<Stream::Type>(uint16_t(nextDir->compression));

  /* Store the next directory entry */
  nextDir = nextDir->GetNext();
  nextFile = nullptr;
  return true;
}

const Zip::DirectoryEntry* Zip::GetFirstEntry() const {
  if (entries) return entries;

  const CentralDirectoryEnd* end = nullptr;
  const char* _end =
      static_cast<const char*>(mapped) + size - sizeof(CentralDirectoryEnd);

  /* Scan for the Central Directory End */
  for (; _end > mapped && !end; _end--)
    end = CentralDirectoryEnd::validate(_end);
  if (!end) {
    ERROR("%s - Couldn't find end of central directory record", name);
    return nullptr;
  }

  entries =
      DirectoryEntry::validate(static_cast<const char*>(mapped) + end->offset);
  if (!entries) {
    ERROR("%s - Couldn't find central directory record", name);
  }
  return entries;
}

bool Zip::VerifyCRCs() const {
  AutoLock lock(&mutex);

  for (const DirectoryEntry* entry = GetFirstEntry(); entry;
       entry = entry->GetNext()) {
    const LocalFile* file =
        LocalFile::validate(static_cast<const char*>(mapped) + entry->offset);
    uint32_t crc = crc32(0, nullptr, 0);

    DEBUG_LOG("%.*s: crc=%08x", int(entry->filenameSize),
              reinterpret_cast<const char*>(entry) + sizeof(*entry),
              uint32_t(entry->CRC32));

    if (entry->compression == Stream::Type::STORE) {
      crc = crc32(crc, static_cast<const uint8_t*>(file->GetData()),
                  entry->compressedSize);
      DEBUG_LOG(" STORE size=%d crc=%08x", int(entry->compressedSize), crc);

    } else if (entry->compression == Stream::Type::DEFLATE) {
      z_stream zstream;
      Bytef buffer[1024];
      zstream.avail_in = entry->compressedSize;
      zstream.next_in =
          reinterpret_cast<Bytef*>(const_cast<void*>(file->GetData()));
      zstream.zalloc = nullptr;
      zstream.zfree = nullptr;
      zstream.opaque = nullptr;

      if (inflateInit2(&zstream, -MAX_WBITS) != Z_OK) {
        return false;
      }

      for (;;) {
        zstream.avail_out = sizeof(buffer);
        zstream.next_out = buffer;

        int ret = inflate(&zstream, Z_SYNC_FLUSH);
        crc = crc32(crc, buffer, sizeof(buffer) - zstream.avail_out);

        if (ret == Z_STREAM_END) {
          break;
        } else if (ret != Z_OK) {
          return false;
        }
      }

      inflateEnd(&zstream);
      DEBUG_LOG(" DEFLATE size=%d crc=%08x", int(zstream.total_out), crc);

    } else {
      MOZ_ASSERT_UNREACHABLE("Unexpected stream type");
      continue;
    }

    if (entry->CRC32 != crc) {
      return false;
    }
  }

  return true;
}

ZipCollection ZipCollection::Singleton;

static pthread_mutex_t sZipCollectionMutex = PTHREAD_MUTEX_INITIALIZER;

already_AddRefed<Zip> ZipCollection::GetZip(const char* path) {
  {
    AutoLock lock(&sZipCollectionMutex);
    /* Search the list of Zips we already have for a match */
    for (const auto& zip : Singleton.zips) {
      if (zip->GetName() && (strcmp(zip->GetName(), path) == 0)) {
        return RefPtr<Zip>(zip).forget();
      }
    }
  }
  return Zip::Create(path);
}

void ZipCollection::Register(Zip* zip) {
  AutoLock lock(&sZipCollectionMutex);
  DEBUG_LOG("ZipCollection::Register(\"%s\")", zip->GetName());
  Singleton.zips.push_back(zip);
}

void ZipCollection::Forget(const Zip* zip) {
  AutoLock lock(&sZipCollectionMutex);
  if (zip->refCount() > 1) {
    // Someone has acquired a reference before we had acquired the lock,
    // ignore this request.
    return;
  }
  DEBUG_LOG("ZipCollection::Forget(\"%s\")", zip->GetName());
  const auto it = std::find(Singleton.zips.begin(), Singleton.zips.end(), zip);
  if (*it == zip) {
    Singleton.zips.erase(it);
  } else {
    DEBUG_LOG("ZipCollection::Forget: didn't find \"%s\" in bookkeeping",
              zip->GetName());
  }
}