1 files changed, 229 insertions, 0 deletions
diff --git a/mozglue/linker/Zip.cpp b/mozglue/linker/Zip.cpp
new file mode 100644
index 000000000..d141eaa45
--- /dev/null
+++ b/mozglue/linker/Zip.cpp
@@ -0,0 +1,229 @@
+/* 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()
+{
+  ZipCollection::Forget(this);
+  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;
+}
+
+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 (std::vector<Zip *>::iterator it = Singleton.zips.begin();
+         it < Singleton.zips.end(); ++it) {
+      if ((*it)->GetName() && (strcmp((*it)->GetName(), path) == 0)) {
+        RefPtr<Zip> zip = *it;
+        return 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(Zip *zip)
+{
+  AutoLock lock(&sZipCollectionMutex);
+  DEBUG_LOG("ZipCollection::Forget(\"%s\")", zip->GetName());
+  std::vector<Zip *>::iterator 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());
+  }
+}