gecko-dev/xpcom/ds/nsPersistentProperties.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsArrayEnumerator.h"
#include "nsID.h"
#include "nsCOMArray.h"
#include "nsUnicharInputStream.h"
#include "nsPrintfCString.h"

#define PL_ARENA_CONST_ALIGN_MASK 3
#include "nsPersistentProperties.h"
#include "nsIProperties.h"

struct PropertyTableEntry : public PLDHashEntryHdr
{
  // both of these are arena-allocated
  const char *mKey;
  const PRUnichar *mValue;
};

static PRUnichar*
ArenaStrdup(const nsAFlatString& aString, PLArenaPool* aArena)
{
  void *mem;
  // add one to include the null terminator
  int32_t len = (aString.Length()+1) * sizeof(PRUnichar);
  PL_ARENA_ALLOCATE(mem, aArena, len);
  NS_ASSERTION(mem, "Couldn't allocate space!\n");
  if (mem) {
    memcpy(mem, aString.get(), len);
  }
  return static_cast<PRUnichar*>(mem);
}

static char*
ArenaStrdup(const nsAFlatCString& aString, PLArenaPool* aArena)
{
  void *mem;
  // add one to include the null terminator
  int32_t len = (aString.Length()+1) * sizeof(char);
  PL_ARENA_ALLOCATE(mem, aArena, len);
  NS_ASSERTION(mem, "Couldn't allocate space!\n");
  if (mem)
    memcpy(mem, aString.get(), len);
  return static_cast<char*>(mem);
}

static const struct PLDHashTableOps property_HashTableOps = {
  PL_DHashAllocTable,
  PL_DHashFreeTable,
  PL_DHashStringKey,
  PL_DHashMatchStringKey,
  PL_DHashMoveEntryStub,
  PL_DHashClearEntryStub,
  PL_DHashFinalizeStub,
  nullptr,
};

//
// parser stuff
//
enum EParserState {
  eParserState_AwaitingKey,
  eParserState_Key,
  eParserState_AwaitingValue,
  eParserState_Value,
  eParserState_Comment
};

enum EParserSpecial {
  eParserSpecial_None,          // not parsing a special character
  eParserSpecial_Escaped,       // awaiting a special character
  eParserSpecial_Unicode        // parsing a \Uxxx value
};

class nsPropertiesParser
{
public:
  nsPropertiesParser(nsIPersistentProperties* aProps) :
    mHaveMultiLine(false), mState(eParserState_AwaitingKey),
    mProps(aProps) {}

  void FinishValueState(nsAString& aOldValue) {
    static const char trimThese[] = " \t";
    mKey.Trim(trimThese, false, true);

    // This is really ugly hack but it should be fast
    PRUnichar backup_char;
    uint32_t minLength = mMinLength;
    if (minLength)
    {
      backup_char = mValue[minLength-1];
      mValue.SetCharAt('x', minLength-1);
    }
    mValue.Trim(trimThese, false, true);
    if (minLength)
      mValue.SetCharAt(backup_char, minLength-1);

    mProps->SetStringProperty(NS_ConvertUTF16toUTF8(mKey), mValue, aOldValue);
    mSpecialState = eParserSpecial_None;
    WaitForKey();
  }

  EParserState GetState() { return mState; }

  static NS_METHOD SegmentWriter(nsIUnicharInputStream* aStream,
                                 void* aClosure,
                                 const PRUnichar *aFromSegment,
                                 uint32_t aToOffset,
                                 uint32_t aCount,
                                 uint32_t *aWriteCount);

  nsresult ParseBuffer(const PRUnichar* aBuffer, uint32_t aBufferLength);

private:
  bool ParseValueCharacter(
    PRUnichar c,                  // character that is just being parsed
    const PRUnichar* cur,         // pointer to character c in the buffer
    const PRUnichar* &tokenStart, // string copying is done in blocks as big as
                                  // possible, tokenStart points to the beginning
                                  // of this block
    nsAString& oldValue);         // when duplicate property is found, new value
                                  // is stored into hashtable and the old one is
                                  // placed in this variable

  void WaitForKey() {
    mState = eParserState_AwaitingKey;
  }

  void EnterKeyState() {
    mKey.Truncate();
    mState = eParserState_Key;
  }

  void WaitForValue() {
    mState = eParserState_AwaitingValue;
  }

  void EnterValueState() {
    mValue.Truncate();
    mMinLength = 0;
    mState = eParserState_Value;
    mSpecialState = eParserSpecial_None;
  }

  void EnterCommentState() {
    mState = eParserState_Comment;
  }

  nsAutoString mKey;
  nsAutoString mValue;

  uint32_t  mUnicodeValuesRead; // should be 4!
  PRUnichar mUnicodeValue;      // currently parsed unicode value
  bool      mHaveMultiLine;     // is TRUE when last processed characters form
                                // any of following sequences:
                                //  - "\\\r"
                                //  - "\\\n"
                                //  - "\\\r\n"
                                //  - any sequence above followed by any
                                //    combination of ' ' and '\t'
  bool      mMultiLineCanSkipN; // TRUE if "\\\r" was detected
  uint32_t  mMinLength;         // limit right trimming at the end to not trim
                                // escaped whitespaces
  EParserState mState;
  // if we see a '\' then we enter this special state
  EParserSpecial mSpecialState;
  nsIPersistentProperties* mProps;
};

inline bool IsWhiteSpace(PRUnichar aChar)
{
  return (aChar == ' ') || (aChar == '\t') ||
         (aChar == '\r') || (aChar == '\n');
}

inline bool IsEOL(PRUnichar aChar)
{
  return (aChar == '\r') || (aChar == '\n');
}


bool nsPropertiesParser::ParseValueCharacter(
    PRUnichar c, const PRUnichar* cur, const PRUnichar* &tokenStart,
    nsAString& oldValue)
{
  switch (mSpecialState) {

    // the normal state - look for special characters
  case eParserSpecial_None:
    switch (c) {
    case '\\':
      if (mHaveMultiLine)
        // there is nothing to append to mValue yet
        mHaveMultiLine = false;
      else
        mValue += Substring(tokenStart, cur);

      mSpecialState = eParserSpecial_Escaped;
      break;

    case '\n':
      // if we detected multiline and got only "\\\r" ignore next "\n" if any
      if (mHaveMultiLine && mMultiLineCanSkipN) {
        // but don't allow another '\n' to be skipped
        mMultiLineCanSkipN = false;
        // Now there is nothing to append to the mValue since we are skipping
        // whitespaces at the beginning of the new line of the multiline
        // property. Set tokenStart properly to ensure that nothing is appended
        // if we find regular line-end or the end of the buffer.
        tokenStart = cur+1;
        break;
      }
      // no break

    case '\r':
      // we're done! We have a key and value
      mValue += Substring(tokenStart, cur);
      FinishValueState(oldValue);
      mHaveMultiLine = false;
      break;

    default:
      // there is nothing to do with normal characters,
      // but handle multilines correctly
      if (mHaveMultiLine) {
        if (c == ' ' || c == '\t') {
          // don't allow another '\n' to be skipped
          mMultiLineCanSkipN = false;
          // Now there is nothing to append to the mValue since we are skipping
          // whitespaces at the beginning of the new line of the multiline
          // property. Set tokenStart properly to ensure that nothing is appended
          // if we find regular line-end or the end of the buffer.
          tokenStart = cur+1;
          break;
        }
        mHaveMultiLine = false;
        tokenStart = cur;
      }
      break; // from switch on (c)
    }
    break; // from switch on (mSpecialState)

    // saw a \ character, so parse the character after that
  case eParserSpecial_Escaped:
    // probably want to start parsing at the next token
    // other characters, like 'u' might override this
    tokenStart = cur+1;
    mSpecialState = eParserSpecial_None;

    switch (c) {

      // the easy characters - \t, \n, and so forth
    case 't':
      mValue += PRUnichar('\t');
      mMinLength = mValue.Length();
      break;
    case 'n':
      mValue += PRUnichar('\n');
      mMinLength = mValue.Length();
      break;
    case 'r':
      mValue += PRUnichar('\r');
      mMinLength = mValue.Length();
      break;
    case '\\':
      mValue += PRUnichar('\\');
      break;

      // switch to unicode mode!
    case 'u':
    case 'U':
      mSpecialState = eParserSpecial_Unicode;
      mUnicodeValuesRead = 0;
      mUnicodeValue = 0;
      break;

      // a \ immediately followed by a newline means we're going multiline
    case '\r':
    case '\n':
      mHaveMultiLine = true;
      mMultiLineCanSkipN = (c == '\r');
      mSpecialState = eParserSpecial_None;
      break;

    default:
      // don't recognize the character, so just append it
      mValue += c;
      break;
    }
    break;

    // we're in the middle of parsing a 4-character unicode value
    // like \u5f39
  case eParserSpecial_Unicode:

    if(('0' <= c) && (c <= '9'))
      mUnicodeValue =
        (mUnicodeValue << 4) | (c - '0');
    else if(('a' <= c) && (c <= 'f'))
      mUnicodeValue =
        (mUnicodeValue << 4) | (c - 'a' + 0x0a);
    else if(('A' <= c) && (c <= 'F'))
      mUnicodeValue =
        (mUnicodeValue << 4) | (c - 'A' + 0x0a);
    else {
      // non-hex character. Append what we have, and move on.
      mValue += mUnicodeValue;
      mMinLength = mValue.Length();
      mSpecialState = eParserSpecial_None;

      // leave tokenStart at this unknown character, so it gets appended
      tokenStart = cur;

      // ensure parsing this non-hex character again
      return false;
    }

    if (++mUnicodeValuesRead >= 4) {
      tokenStart = cur+1;
      mSpecialState = eParserSpecial_None;
      mValue += mUnicodeValue;
      mMinLength = mValue.Length();
    }

    break;
  }

  return true;
}

NS_METHOD nsPropertiesParser::SegmentWriter(nsIUnicharInputStream* aStream,
                                            void* aClosure,
                                            const PRUnichar *aFromSegment,
                                            uint32_t aToOffset,
                                            uint32_t aCount,
                                            uint32_t *aWriteCount)
{
  nsPropertiesParser *parser = 
    static_cast<nsPropertiesParser *>(aClosure);
  
  parser->ParseBuffer(aFromSegment, aCount);

  *aWriteCount = aCount;
  return NS_OK;
}

nsresult nsPropertiesParser::ParseBuffer(const PRUnichar* aBuffer,
                                         uint32_t aBufferLength)
{
  const PRUnichar* cur = aBuffer;
  const PRUnichar* end = aBuffer + aBufferLength;

  // points to the start/end of the current key or value
  const PRUnichar* tokenStart = nullptr;

  // if we're in the middle of parsing a key or value, make sure
  // the current token points to the beginning of the current buffer
  if (mState == eParserState_Key ||
      mState == eParserState_Value) {
    tokenStart = aBuffer;
  }

  nsAutoString oldValue;

  while (cur != end) {

    PRUnichar c = *cur;

    switch (mState) {
    case eParserState_AwaitingKey:
      if (c == '#' || c == '!')
        EnterCommentState();

      else if (!IsWhiteSpace(c)) {
        // not a comment, not whitespace, we must have found a key!
        EnterKeyState();
        tokenStart = cur;
      }
      break;

    case eParserState_Key:
      if (c == '=' || c == ':') {
        mKey += Substring(tokenStart, cur);
        WaitForValue();
      }
      break;

    case eParserState_AwaitingValue:
      if (IsEOL(c)) {
        // no value at all! mimic the normal value-ending
        EnterValueState();
        FinishValueState(oldValue);
      }

      // ignore white space leading up to the value
      else if (!IsWhiteSpace(c)) {
        tokenStart = cur;
        EnterValueState();

        // make sure to handle this first character
        if (ParseValueCharacter(c, cur, tokenStart, oldValue))
          cur++;
        // If the character isn't consumed, don't do cur++ and parse
        // the character again. This can happen f.e. for char 'X' in sequence
        // "\u00X". This character can be control character and must be
        // processed again.
        continue;
      }
      break;

    case eParserState_Value:
      if (ParseValueCharacter(c, cur, tokenStart, oldValue))
        cur++;
      // See few lines above for reason of doing this
      continue;

    case eParserState_Comment:
      // stay in this state till we hit EOL
      if (c == '\r' || c== '\n')
        WaitForKey();
      break;
    }

    // finally, advance to the next character
    cur++;
  }

  // if we're still parsing the value and are in eParserSpecial_None, then
  // append whatever we have..
  if (mState == eParserState_Value && tokenStart &&
      mSpecialState == eParserSpecial_None) {
    mValue += Substring(tokenStart, cur);
  }
  // if we're still parsing the key, then append whatever we have..
  else if (mState == eParserState_Key && tokenStart) {
    mKey += Substring(tokenStart, cur);
  }

  return NS_OK;
}

nsPersistentProperties::nsPersistentProperties()
: mIn(nullptr)
{
  mSubclass = static_cast<nsIPersistentProperties*>(this);
  mTable.ops = nullptr;
  PL_INIT_ARENA_POOL(&mArena, "PersistentPropertyArena", 2048);
}

nsPersistentProperties::~nsPersistentProperties()
{
  PL_FinishArenaPool(&mArena);
  if (mTable.ops)
    PL_DHashTableFinish(&mTable);
}

nsresult
nsPersistentProperties::Init()
{
  if (!PL_DHashTableInit(&mTable, &property_HashTableOps, nullptr,
                         sizeof(PropertyTableEntry), 20)) {
    mTable.ops = nullptr;
    return NS_ERROR_OUT_OF_MEMORY;
  }
  return NS_OK;
}

nsresult
nsPersistentProperties::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
{
  if (aOuter)
    return NS_ERROR_NO_AGGREGATION;
  nsPersistentProperties* props = new nsPersistentProperties();
  if (props == nullptr)
    return NS_ERROR_OUT_OF_MEMORY;

  NS_ADDREF(props);
  nsresult rv = props->Init();
  if (NS_SUCCEEDED(rv))
    rv = props->QueryInterface(aIID, aResult);

  NS_RELEASE(props);
  return rv;
}

NS_IMPL_ISUPPORTS2(nsPersistentProperties, nsIPersistentProperties, nsIProperties)

NS_IMETHODIMP
nsPersistentProperties::Load(nsIInputStream *aIn)
{
  nsresult rv = nsSimpleUnicharStreamFactory::GetInstance()->
    CreateInstanceFromUTF8Stream(aIn, getter_AddRefs(mIn));

  if (rv != NS_OK) {
    NS_WARNING("Error creating UnicharInputStream");
    return NS_ERROR_FAILURE;
  }

  nsPropertiesParser parser(mSubclass);

  uint32_t nProcessed;
  // If this 4096 is changed to some other value, make sure to adjust
  // the bug121341.properties test file accordingly.
  while (NS_SUCCEEDED(rv = mIn->ReadSegments(nsPropertiesParser::SegmentWriter, &parser, 4096, &nProcessed)) &&
         nProcessed != 0);
  mIn = nullptr;
  if (NS_FAILED(rv))
    return rv;

  // We may have an unprocessed value at this point
  // if the last line did not have a proper line ending.
  if (parser.GetState() == eParserState_Value) {
    nsAutoString oldValue;  
    parser.FinishValueState(oldValue);
  }

  return NS_OK;
}

NS_IMETHODIMP
nsPersistentProperties::SetStringProperty(const nsACString& aKey,
                                          const nsAString& aNewValue,
                                          nsAString& aOldValue)
{
  const nsAFlatCString&  flatKey = PromiseFlatCString(aKey);
  PropertyTableEntry *entry =
    static_cast<PropertyTableEntry*>
               (PL_DHashTableOperate(&mTable, flatKey.get(), PL_DHASH_ADD));

  if (entry->mKey) {
    aOldValue = entry->mValue;
    NS_WARNING(nsPrintfCString("the property %s already exists\n",
                               flatKey.get()).get());
  }
  else {
    aOldValue.Truncate();
  }

  entry->mKey = ArenaStrdup(flatKey, &mArena);
  entry->mValue = ArenaStrdup(PromiseFlatString(aNewValue), &mArena);

  return NS_OK;
}

NS_IMETHODIMP
nsPersistentProperties::Save(nsIOutputStream* aOut, const nsACString& aHeader)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsPersistentProperties::Subclass(nsIPersistentProperties* aSubclass)
{
  if (aSubclass) {
    mSubclass = aSubclass;
  }

  return NS_OK;
}

NS_IMETHODIMP
nsPersistentProperties::GetStringProperty(const nsACString& aKey,
                                          nsAString& aValue)
{
  const nsAFlatCString&  flatKey = PromiseFlatCString(aKey);

  PropertyTableEntry *entry =
    static_cast<PropertyTableEntry*>
               (PL_DHashTableOperate(&mTable, flatKey.get(), PL_DHASH_LOOKUP));

  if (PL_DHASH_ENTRY_IS_FREE(entry))
    return NS_ERROR_FAILURE;

  aValue = entry->mValue;
  return NS_OK;
}

static PLDHashOperator
AddElemToArray(PLDHashTable* table, PLDHashEntryHdr *hdr,
               uint32_t i, void *arg)
{
  nsCOMArray<nsIPropertyElement>* props =
    static_cast<nsCOMArray<nsIPropertyElement>*>(arg);
  PropertyTableEntry* entry =
    static_cast<PropertyTableEntry*>(hdr);

  nsPropertyElement *element =
    new nsPropertyElement(nsDependentCString(entry->mKey),
                          nsDependentString(entry->mValue));

  props->AppendObject(element);

  return PL_DHASH_NEXT;
}


NS_IMETHODIMP
nsPersistentProperties::Enumerate(nsISimpleEnumerator** aResult)
{
  nsCOMArray<nsIPropertyElement> props;

  // We know the necessary size; we can avoid growing it while adding elements
  props.SetCapacity(mTable.entryCount);

  // Step through hash entries populating a transient array
  uint32_t n =
    PL_DHashTableEnumerate(&mTable, AddElemToArray, (void *)&props);
  if (n < mTable.entryCount)
    return NS_ERROR_OUT_OF_MEMORY;

  return NS_NewArrayEnumerator(aResult, props);
}

////////////////////////////////////////////////////////////////////////////////
// XXX Some day we'll unify the nsIPersistentProperties interface with
// nsIProperties, but until now...

NS_IMETHODIMP
nsPersistentProperties::Get(const char* prop, const nsIID & uuid, void* *result)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsPersistentProperties::Set(const char* prop, nsISupports* value)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}
NS_IMETHODIMP
nsPersistentProperties::Undefine(const char* prop)
{
  return NS_ERROR_NOT_IMPLEMENTED;
}

NS_IMETHODIMP
nsPersistentProperties::Has(const char* prop, bool *result)
{
  PropertyTableEntry *entry =
    static_cast<PropertyTableEntry*>
               (PL_DHashTableOperate(&mTable, prop, PL_DHASH_LOOKUP));

  *result = (entry && PL_DHASH_ENTRY_IS_BUSY(entry));

  return NS_OK;
}

NS_IMETHODIMP
nsPersistentProperties::GetKeys(uint32_t *count, char ***keys)
{
    return NS_ERROR_NOT_IMPLEMENTED;
}

////////////////////////////////////////////////////////////////////////////////
// PropertyElement
////////////////////////////////////////////////////////////////////////////////

NS_METHOD
nsPropertyElement::Create(nsISupports *aOuter, REFNSIID aIID, void **aResult)
{
  if (aOuter)
    return NS_ERROR_NO_AGGREGATION;
  nsPropertyElement* propElem = new nsPropertyElement();
  if (propElem == nullptr)
    return NS_ERROR_OUT_OF_MEMORY;
  NS_ADDREF(propElem);
  nsresult rv = propElem->QueryInterface(aIID, aResult);
  NS_RELEASE(propElem);
  return rv;
}

NS_IMPL_ISUPPORTS1(nsPropertyElement, nsIPropertyElement)

NS_IMETHODIMP
nsPropertyElement::GetKey(nsACString& aReturnKey)
{
  aReturnKey = mKey;
  return NS_OK;
}

NS_IMETHODIMP
nsPropertyElement::GetValue(nsAString& aReturnValue)
{
  aReturnValue = mValue;
  return NS_OK;
}

NS_IMETHODIMP
nsPropertyElement::SetKey(const nsACString& aKey)
{
  mKey = aKey;
  return NS_OK;
}

NS_IMETHODIMP
nsPropertyElement::SetValue(const nsAString& aValue)
{
  mValue = aValue;
  return NS_OK;
}

////////////////////////////////////////////////////////////////////////////////