gecko-dev/netwerk/cache2/CacheFileUtils.cpp

430 строки
9.7 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 "CacheLog.h"
#include "CacheFileUtils.h"
#include "LoadContextInfo.h"
#include "nsCOMPtr.h"
#include "nsAutoPtr.h"
#include "nsString.h"
#include <algorithm>
namespace mozilla {
namespace net {
namespace CacheFileUtils {
namespace { // anon
/**
* A simple recursive descent parser for the mapping key.
*/
class KeyParser
{
public:
KeyParser(nsACString::const_iterator aCaret, nsACString::const_iterator aEnd)
: caret(aCaret)
, end(aEnd)
// Initialize attributes to their default values
, appId(nsILoadContextInfo::NO_APP_ID)
, isPrivate(false)
, isInBrowser(false)
, isAnonymous(false)
// Initialize the cache key to a zero length by default
, cacheKey(aEnd)
, lastTag(0)
{
}
private:
// Current character being parsed
nsACString::const_iterator caret;
// The end of the buffer
nsACString::const_iterator const end;
// Results
uint32_t appId;
bool isPrivate;
bool isInBrowser;
bool isAnonymous;
nsCString idEnhance;
// Position of the cache key, if present
nsACString::const_iterator cacheKey;
// Keeps the last tag name, used for alphabetical sort checking
char lastTag;
bool ParseTags()
{
// Expects to be at the tag name or at the end
if (caret == end)
return true;
// 'Read' the tag name and move to the next char
char const tag = *caret++;
// Check the alphabetical order, hard-fail on disobedience
if (!(lastTag < tag || tag == ':'))
return false;
lastTag = tag;
switch (tag) {
case ':':
// last possible tag, when present there is the cacheKey following,
// not terminated with ',' and no need to unescape.
cacheKey = caret;
caret = end;
return true;
case 'p':
isPrivate = true;
break;
case 'b':
isInBrowser = true;
break;
case 'a':
isAnonymous = true;
break;
case 'i': {
nsAutoCString appIdString;
if (!ParseValue(&appIdString))
return false;
nsresult rv;
int64_t appId64 = appIdString.ToInteger64(&rv);
if (NS_FAILED(rv))
return false; // appid value is mandatory
if (appId64 < 0 || appId64 > PR_UINT32_MAX)
return false; // not in the range
appId = static_cast<uint32_t>(appId64);
break;
}
case '~':
if (!ParseValue(&idEnhance))
return false;
break;
default:
if (!ParseValue()) // skip any tag values, optional
return false;
break;
}
// Recurse to the next tag
return ParseNextTagOrEnd();
}
bool ParseNextTagOrEnd()
{
// We expect a comma after every tag
if (caret == end || *caret++ != ',')
return false;
// Go to another tag
return ParseTags();
}
bool ParseValue(nsACString * result = nullptr)
{
// If at the end, fail since we expect a comma ; value may be empty tho
if (caret == end)
return false;
// Remeber where the value starts
nsACString::const_iterator val = caret;
nsACString::const_iterator comma = end;
bool escape = false;
while (caret != end) {
nsACString::const_iterator at = caret;
++caret; // we can safely break/continue the loop now
if (*at == ',') {
if (comma != end) {
// another comma (we have found ",," -> escape)
comma = end;
escape = true;
} else {
comma = at;
}
continue;
}
if (comma != end) {
// after a single comma
break;
}
}
// At this point |comma| points to the last and lone ',' we've hit.
// If a lone comma was not found, |comma| is at the end of the buffer,
// that is not expected and we return failure.
caret = comma;
if (result) {
if (escape) {
// No ReplaceSubstring on nsACString..
nsAutoCString _result(Substring(val, caret));
_result.ReplaceSubstring(NS_LITERAL_CSTRING(",,"), NS_LITERAL_CSTRING(","));
result->Assign(_result);
} else {
result->Assign(Substring(val, caret));
}
}
return caret != end;
}
public:
already_AddRefed<LoadContextInfo> Parse()
{
nsRefPtr<LoadContextInfo> info;
if (ParseTags())
info = GetLoadContextInfo(isPrivate, appId, isInBrowser, isAnonymous);
return info.forget();
}
void URISpec(nsACString &result)
{
// cacheKey is either pointing to end or the position where the cache key is.
result.Assign(Substring(cacheKey, end));
}
void IdEnhance(nsACString &result)
{
result.Assign(idEnhance);
}
};
} // anon
already_AddRefed<nsILoadContextInfo>
ParseKey(const nsCSubstring &aKey,
nsCSubstring *aIdEnhance,
nsCSubstring *aURISpec)
{
nsACString::const_iterator caret, end;
aKey.BeginReading(caret);
aKey.EndReading(end);
KeyParser parser(caret, end);
nsRefPtr<LoadContextInfo> info = parser.Parse();
if (info) {
if (aIdEnhance)
parser.IdEnhance(*aIdEnhance);
if (aURISpec)
parser.URISpec(*aURISpec);
}
return info.forget();
}
void
AppendKeyPrefix(nsILoadContextInfo* aInfo, nsACString &_retval)
{
/**
* This key is used to salt file hashes. When form of the key is changed
* cache entries will fail to find on disk.
*
* IMPORTANT NOTE:
* Keep the attributes list sorted according their ASCII code.
*/
if (aInfo->IsAnonymous()) {
_retval.AppendLiteral("a,");
}
if (aInfo->IsInBrowserElement()) {
_retval.AppendLiteral("b,");
}
if (aInfo->AppId() != nsILoadContextInfo::NO_APP_ID) {
_retval.Append('i');
_retval.AppendInt(aInfo->AppId());
_retval.Append(',');
}
if (aInfo->IsPrivate()) {
_retval.AppendLiteral("p,");
}
}
void
AppendTagWithValue(nsACString & aTarget, char const aTag, nsCSubstring const & aValue)
{
aTarget.Append(aTag);
// First check the value string to save some memory copying
// for cases we don't need to escape at all (most likely).
if (!aValue.IsEmpty()) {
if (aValue.FindChar(',') == kNotFound) {
// No need to escape
aTarget.Append(aValue);
} else {
nsAutoCString escapedValue(aValue);
escapedValue.ReplaceSubstring(
NS_LITERAL_CSTRING(","), NS_LITERAL_CSTRING(",,"));
aTarget.Append(escapedValue);
}
}
aTarget.Append(',');
}
nsresult
KeyMatchesLoadContextInfo(const nsACString &aKey, nsILoadContextInfo *aInfo,
bool *_retval)
{
nsCOMPtr<nsILoadContextInfo> info = ParseKey(aKey);
if (!info) {
return NS_ERROR_FAILURE;
}
*_retval = info->Equals(aInfo);
return NS_OK;
}
ValidityPair::ValidityPair(uint32_t aOffset, uint32_t aLen)
: mOffset(aOffset), mLen(aLen)
{}
ValidityPair&
ValidityPair::operator=(const ValidityPair& aOther)
{
mOffset = aOther.mOffset;
mLen = aOther.mLen;
return *this;
}
bool
ValidityPair::CanBeMerged(const ValidityPair& aOther) const
{
// The pairs can be merged into a single one if the start of one of the pairs
// is placed anywhere in the validity interval of other pair or exactly after
// its end.
return IsInOrFollows(aOther.mOffset) || aOther.IsInOrFollows(mOffset);
}
bool
ValidityPair::IsInOrFollows(uint32_t aOffset) const
{
return mOffset <= aOffset && mOffset + mLen >= aOffset;
}
bool
ValidityPair::LessThan(const ValidityPair& aOther) const
{
if (mOffset < aOther.mOffset) {
return true;
}
if (mOffset == aOther.mOffset && mLen < aOther.mLen) {
return true;
}
return false;
}
void
ValidityPair::Merge(const ValidityPair& aOther)
{
MOZ_ASSERT(CanBeMerged(aOther));
uint32_t offset = std::min(mOffset, aOther.mOffset);
uint32_t end = std::max(mOffset + mLen, aOther.mOffset + aOther.mLen);
mOffset = offset;
mLen = end - offset;
}
void
ValidityMap::Log() const
{
LOG(("ValidityMap::Log() - number of pairs: %u", mMap.Length()));
for (uint32_t i=0; i<mMap.Length(); i++) {
LOG((" (%u, %u)", mMap[i].Offset() + 0, mMap[i].Len() + 0));
}
}
uint32_t
ValidityMap::Length() const
{
return mMap.Length();
}
void
ValidityMap::AddPair(uint32_t aOffset, uint32_t aLen)
{
ValidityPair pair(aOffset, aLen);
if (mMap.Length() == 0) {
mMap.AppendElement(pair);
return;
}
// Find out where to place this pair into the map, it can overlap only with
// one preceding pair and all subsequent pairs.
uint32_t pos = 0;
for (pos = mMap.Length(); pos > 0; ) {
--pos;
if (mMap[pos].LessThan(pair)) {
// The new pair should be either inserted after pos or merged with it.
if (mMap[pos].CanBeMerged(pair)) {
// Merge with the preceding pair
mMap[pos].Merge(pair);
} else {
// They don't overlap, element must be placed after pos element
++pos;
if (pos == mMap.Length()) {
mMap.AppendElement(pair);
} else {
mMap.InsertElementAt(pos, pair);
}
}
break;
}
if (pos == 0) {
// The new pair should be placed in front of all existing pairs.
mMap.InsertElementAt(0, pair);
}
}
// pos now points to merged or inserted pair, check whether it overlaps with
// subsequent pairs.
while (pos + 1 < mMap.Length()) {
if (mMap[pos].CanBeMerged(mMap[pos + 1])) {
mMap[pos].Merge(mMap[pos + 1]);
mMap.RemoveElementAt(pos + 1);
} else {
break;
}
}
}
void
ValidityMap::Clear()
{
mMap.Clear();
}
size_t
ValidityMap::SizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const
{
return mMap.SizeOfExcludingThis(mallocSizeOf);
}
ValidityPair&
ValidityMap::operator[](uint32_t aIdx)
{
return mMap.ElementAt(aIdx);
}
} // CacheFileUtils
} // net
} // mozilla