gecko-dev/widget/nsPrimitiveHelpers.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/. */


//
// Part of the reason these routines are all in once place is so that as new
// data flavors are added that are known to be one-byte or two-byte strings, or even
// raw binary data, then we just have to go to one place to change how the data
// moves into/out of the primitives and native line endings.
//
// If you add new flavors that have special consideration (binary data or one-byte
// char* strings), please update all the helper classes in this file.
//
// For now, this is the assumption that we are making:
//  - text/plain is always a char*
//  - anything else is a char16_t*
//


#include "nsPrimitiveHelpers.h"
#include "nsCOMPtr.h"
#include "nsXPCOM.h"
#include "nsISupportsPrimitives.h"
#include "nsITransferable.h"
#include "nsIComponentManager.h"
#include "nsLinebreakConverter.h"
#include "nsReadableUtils.h"


//
// CreatePrimitiveForData
//
// Given some data and the flavor it corresponds to, creates the appropriate
// nsISupports* wrapper for passing across IDL boundaries. Right now, everything
// creates a two-byte |nsISupportsString|, except for "text/plain" and native
// platform HTML (CF_HTML on win32)
//
void
nsPrimitiveHelpers :: CreatePrimitiveForData ( const char* aFlavor, const void* aDataBuff,
                                                 uint32_t aDataLen, nsISupports** aPrimitive )
{
  if ( !aPrimitive )
    return;

  if ( strcmp(aFlavor,kTextMime) == 0 || strcmp(aFlavor,kNativeHTMLMime) == 0 ) {
    nsCOMPtr<nsISupportsCString> primitive =
        do_CreateInstance(NS_SUPPORTS_CSTRING_CONTRACTID);
    if ( primitive ) {
      const char * start = reinterpret_cast<const char*>(aDataBuff);
      primitive->SetData(Substring(start, start + aDataLen));
      NS_ADDREF(*aPrimitive = primitive);
    }
  }
  else {
    nsCOMPtr<nsISupportsString> primitive =
        do_CreateInstance(NS_SUPPORTS_STRING_CONTRACTID);
    if (primitive ) {
      if (aDataLen % 2) {
        nsAutoArrayPtr<char> buffer(new char[aDataLen + 1]);
        if (!MOZ_LIKELY(buffer))
          return;

        memcpy(buffer, aDataBuff, aDataLen);
        buffer[aDataLen] = 0;
        const char16_t* start = reinterpret_cast<const char16_t*>(buffer.get());
        // recall that length takes length as characters, not bytes
        primitive->SetData(Substring(start, start + (aDataLen + 1) / 2));
      } else {
        const char16_t* start = reinterpret_cast<const char16_t*>(aDataBuff);
        // recall that length takes length as characters, not bytes
        primitive->SetData(Substring(start, start + (aDataLen / 2)));
      }
      NS_ADDREF(*aPrimitive = primitive);
    }
  }

} // CreatePrimitiveForData


//
// CreateDataFromPrimitive
//
// Given a nsISupports* primitive and the flavor it represents, creates a new data
// buffer with the data in it. This data will be null terminated, but the length
// parameter does not reflect that.
//
void
nsPrimitiveHelpers :: CreateDataFromPrimitive ( const char* aFlavor, nsISupports* aPrimitive,
                                                   void** aDataBuff, uint32_t aDataLen )
{
  if ( !aDataBuff )
    return;

  *aDataBuff = nullptr;

  if ( strcmp(aFlavor,kTextMime) == 0 ) {
    nsCOMPtr<nsISupportsCString> plainText ( do_QueryInterface(aPrimitive) );
    if ( plainText ) {
      nsAutoCString data;
      plainText->GetData ( data );
      *aDataBuff = ToNewCString(data);
    }
  }
  else {
    nsCOMPtr<nsISupportsString> doubleByteText ( do_QueryInterface(aPrimitive) );
    if ( doubleByteText ) {
      nsAutoString data;
      doubleByteText->GetData ( data );
      *aDataBuff = ToNewUnicode(data);
    }
  }

}


//
// ConvertPlatformToDOMLinebreaks
//
// Given some data, convert from the platform linebreaks into the LF expected by the
// DOM. This will attempt to convert the data in place, but the buffer may still need to
// be reallocated regardless (disposing the old buffer is taken care of internally, see
// the note below).
//
// NOTE: this assumes that it can use 'free' to dispose of the old buffer.
//
nsresult
nsLinebreakHelpers :: ConvertPlatformToDOMLinebreaks ( const char* inFlavor, void** ioData,
                                                          int32_t* ioLengthInBytes )
{
  NS_ASSERTION ( ioData && *ioData && ioLengthInBytes, "Bad Params");
  if ( !(ioData && *ioData && ioLengthInBytes) )
    return NS_ERROR_INVALID_ARG;

  nsresult retVal = NS_OK;

  if ( strcmp(inFlavor, "text/plain") == 0 ) {
    char* buffAsChars = reinterpret_cast<char*>(*ioData);
    char* oldBuffer = buffAsChars;
    retVal = nsLinebreakConverter::ConvertLineBreaksInSitu ( &buffAsChars, nsLinebreakConverter::eLinebreakAny,
                                                              nsLinebreakConverter::eLinebreakContent,
                                                              *ioLengthInBytes, ioLengthInBytes );
    if ( NS_SUCCEEDED(retVal) ) {
      if ( buffAsChars != oldBuffer )             // check if buffer was reallocated
        free ( oldBuffer );
      *ioData = buffAsChars;
    }
  }
  else if ( strcmp(inFlavor, "image/jpeg") == 0 ) {
    // I'd assume we don't want to do anything for binary data....
  }
  else {
    char16_t* buffAsUnichar = reinterpret_cast<char16_t*>(*ioData);
    char16_t* oldBuffer = buffAsUnichar;
    int32_t newLengthInChars;
    retVal = nsLinebreakConverter::ConvertUnicharLineBreaksInSitu ( &buffAsUnichar, nsLinebreakConverter::eLinebreakAny,
                                                                     nsLinebreakConverter::eLinebreakContent,
                                                                     *ioLengthInBytes / sizeof(char16_t), &newLengthInChars );
    if ( NS_SUCCEEDED(retVal) ) {
      if ( buffAsUnichar != oldBuffer )           // check if buffer was reallocated
        free ( oldBuffer );
      *ioData = buffAsUnichar;
      *ioLengthInBytes = newLengthInChars * sizeof(char16_t);
    }
  }

  return retVal;

} // ConvertPlatformToDOMLinebreaks