The Tor Browser: netwerk/cache2/CacheFileUtils.cpp@7e26c7da4463 (annotated)

netwerk/cache2/CacheFileUtils.cpp@7e26c7da4463 (annotated)

netwerk/cache2/CacheFileUtils.cpp

Wed, 31 Dec 2014 06:55:50 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:55:50 +0100
changeset 2: 7e26c7da4463
permissions: -rw-r--r--

Added tag UPSTREAM_283F7C6 for changeset ca08bd8f51b2

 /* 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"
 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.Append(NS_LITERAL_CSTRING("a,"));
   }
   if (aInfo->IsInBrowserElement()) {
     _retval.Append(NS_LITERAL_CSTRING("b,"));
   }
   if (aInfo->AppId() != nsILoadContextInfo::NO_APP_ID) {
     _retval.Append('i');
     _retval.AppendInt(aInfo->AppId());
     _retval.Append(',');
   }
   if (aInfo->IsPrivate()) {
     _retval.Append(NS_LITERAL_CSTRING("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;
 }
 } // CacheFileUtils
 } // net
 } // mozilla

The Tor Browser / annotate

netwerk/cache2/CacheFileUtils.cpp@7e26c7da4463 (annotated)

netwerk/cache2/CacheFileUtils.cpp