gecko-dev/mozglue/linker/Zip.cpp

181 lines
5.8 KiB
C++

/* 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"
Zip::Zip(const char *filename, ZipCollection *collection)
: name(strdup(filename))
, mapped(MAP_FAILED)
, nextDir(NULL)
, entries(NULL)
, parent(collection)
{
/* Open and map the file in memory */
AutoCloseFD fd(open(name, O_RDONLY));
if (fd == -1) {
log("Error opening %s: %s", filename, strerror(errno));
return;
}
struct stat st;
if (fstat(fd, &st) == -1) {
log("Error stating %s: %s", filename, strerror(errno));
return;
}
size = st.st_size;
if (size <= sizeof(CentralDirectoryEnd)) {
log("Error reading %s: too short", filename);
return;
}
mapped = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
if (mapped == MAP_FAILED) {
log("Error mmapping %s: %s", filename, strerror(errno));
return;
}
debug("Mapped %s @%p", filename, mapped);
/* Store the first Local File entry */
nextFile = LocalFile::validate(mapped);
}
Zip::~Zip()
{
if (parent)
parent->Forget(this);
if (mapped != MAP_FAILED) {
munmap(mapped, size);
debug("Unmapped %s @%p", name, mapped);
}
free(name);
}
bool
Zip::GetStream(const char *path, Zip::Stream *out) const
{
debug("%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("%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->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("%s - Scan directory entries in search for %s", name, path);
while (entry && !entry->GetName().Equals(path)) {
entry = entry->GetNext();
}
nextDir = entry;
}
if (!nextDir) {
debug("%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) {
log("%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->type = static_cast<Stream::Type>(uint16_t(nextDir->compression));
/* Store the next directory entry */
nextDir = nextDir->GetNext();
nextFile = NULL;
return true;
}
const Zip::DirectoryEntry *
Zip::GetFirstEntry() const
{
if (entries || mapped == MAP_FAILED)
return entries; // entries is NULL in the second case above
const CentralDirectoryEnd *end = NULL;
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) {
log("%s - Couldn't find end of central directory record", name);
return NULL;
}
entries = DirectoryEntry::validate(static_cast<const char *>(mapped)
+ end->offset);
if (!entries) {
log("%s - Couldn't find central directory record", name);
}
return entries;
}
mozilla::TemporaryRef<Zip>
ZipCollection::GetZip(const char *path)
{
/* Search the list of Zips we already have for a match */
for (std::vector<Zip *>::iterator it = zips.begin(); it < zips.end(); ++it) {
if (strcmp((*it)->GetName(), path) == 0)
return *it;
}
Zip *zip = new Zip(path, this);
zips.push_back(zip);
return zip;
}
void
ZipCollection::Forget(Zip *zip)
{
debug("ZipCollection::Forget(\"%s\")", zip->GetName());
std::vector<Zip *>::iterator it = std::find(zips.begin(), zips.end(), zip);
if (*it == zip)
zips.erase(it);
else
debug("ZipCollection::Forget: didn't find \"%s\" in bookkeeping", zip->GetName());
}