The Tor Browser: intl/uconv/src/nsUTF8ToUnicode.cpp@6474c204b198 (annotated)

intl/uconv/src/nsUTF8ToUnicode.cpp@6474c204b198 (annotated)

intl/uconv/src/nsUTF8ToUnicode.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=2 et sw=2 tw=80: */
 /* 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 "nsUCSupport.h"
 #include "nsUTF8ToUnicode.h"
 #include "mozilla/SSE.h"
 #include "nsCharTraits.h"
 #include <algorithm>
 #define UNICODE_BYTE_ORDER_MARK    0xFEFF
 static char16_t* EmitSurrogatePair(uint32_t ucs4, char16_t* aDest)
 {
   NS_ASSERTION(ucs4 > 0xFFFF, "Should be a supplementary character");
   ucs4 -= 0x00010000;
   *aDest++ = 0xD800 | (0x000003FF & (ucs4 >> 10));
   *aDest++ = 0xDC00 | (0x000003FF & ucs4);
   return aDest;
 }
 //----------------------------------------------------------------------
 // Class nsUTF8ToUnicode [implementation]
 nsUTF8ToUnicode::nsUTF8ToUnicode()
 : nsBasicDecoderSupport()
 {
   Reset();
 }
 //----------------------------------------------------------------------
 // Subclassing of nsTableDecoderSupport class [implementation]
 /**
  * Normally the maximum length of the output of the UTF8 decoder in UTF16
  *  code units is the same as the length of the input in UTF8 code units,
  *  since 1-byte, 2-byte and 3-byte UTF-8 sequences decode to a single
  *  UTF-16 character, and 4-byte UTF-8 sequences decode to a surrogate pair.
  *
  * However, there is an edge case where the output can be longer than the
  *  input: if the previous buffer ended with an incomplete multi-byte
  *  sequence and this buffer does not begin with a valid continuation
  *  byte, we will return NS_ERROR_ILLEGAL_INPUT and the caller may insert a
  *  replacement character in the output buffer which corresponds to no
  *  character in the input buffer. So in the worst case the destination
  *  will need to be one code unit longer than the source.
  *  See bug 301797.
  */
 NS_IMETHODIMP nsUTF8ToUnicode::GetMaxLength(const char * aSrc,
                                             int32_t aSrcLength,
                                             int32_t * aDestLength)
 {
   *aDestLength = aSrcLength + 1;
   return NS_OK;
 }
 //----------------------------------------------------------------------
 // Subclassing of nsBasicDecoderSupport class [implementation]
 NS_IMETHODIMP nsUTF8ToUnicode::Reset()
 {
   mUcs4  = 0;     // cached Unicode character
   mState = 0;     // cached expected number of octets after the current octet
                   // until the beginning of the next UTF8 character sequence
   mBytes = 1;     // cached expected number of octets in the current sequence
   mFirst = true;
   return NS_OK;
 }
 //----------------------------------------------------------------------
 // Subclassing of nsBasicDecoderSupport class [implementation]
 // Fast ASCII -> UTF16 inner loop implementations
 //
 // Convert_ascii_run will update src and dst to the new values, and
 // len must be the maximum number ascii chars that it would be valid
 // to take from src and place into dst.  (That is, the minimum of the
 // number of bytes left in src and the number of unichars available in
 // dst.)
 #if defined(__arm__) || defined(_M_ARM)
 // on ARM, do extra work to avoid byte/halfword reads/writes by
 // reading/writing a word at a time for as long as we can
 static inline void
 Convert_ascii_run (const char *&src,
                    char16_t *&dst,
                    int32_t len)
 {
   const uint32_t *src32;
   uint32_t *dst32;
   // with some alignments, we'd never actually break out of the slow loop, so
   // check and do the faster slow loop
   if ((((NS_PTR_TO_UINT32(dst) & 3) == 0) && ((NS_PTR_TO_UINT32(src) & 1) == 0)) ||
       (((NS_PTR_TO_UINT32(dst) & 3) == 2) && ((NS_PTR_TO_UINT32(src) & 1) == 1)))
   {
     while (((NS_PTR_TO_UINT32(src) & 3) ||
             (NS_PTR_TO_UINT32(dst) & 3)) &&
            len > 0)
     {
       if (*src & 0x80U)
         return;
       *dst++ = (char16_t) *src++;
       len--;
     }
   } else {
     goto finish;
   }
   // then go 4 bytes at a time
   src32 = (const uint32_t*) src;
   dst32 = (uint32_t*) dst;
   while (len > 4) {
     uint32_t in = *src32++;
     if (in & 0x80808080U) {
       src32--;
       break;
     }
     *dst32++ = ((in & 0x000000ff) >>  0) | ((in & 0x0000ff00) << 8);
     *dst32++ = ((in & 0x00ff0000) >> 16) | ((in & 0xff000000) >> 8);
     len -= 4;
   }
   src = (const char *) src32;
   dst = (char16_t *) dst32;
 finish:
   while (len-- > 0 && (*src & 0x80U) == 0) {
     *dst++ = (char16_t) *src++;
   }
 }
 #else
 #ifdef MOZILLA_MAY_SUPPORT_SSE2
 namespace mozilla {
 namespace SSE2 {
 void Convert_ascii_run(const char *&src, char16_t *&dst, int32_t len);
 }
 }
 #endif
 static inline void
 Convert_ascii_run (const char *&src,
                    char16_t *&dst,
                    int32_t len)
 {
 #ifdef MOZILLA_MAY_SUPPORT_SSE2
   if (mozilla::supports_sse2()) {
     mozilla::SSE2::Convert_ascii_run(src, dst, len);
     return;
   }
 #endif
   while (len-- > 0 && (*src & 0x80U) == 0) {
     *dst++ = (char16_t) *src++;
   }
 }
 #endif
 NS_IMETHODIMP nsUTF8ToUnicode::Convert(const char * aSrc,
                                        int32_t * aSrcLength,
                                        char16_t * aDest,
                                        int32_t * aDestLength)
 {
   uint32_t aSrcLen   = (uint32_t) (*aSrcLength);
   uint32_t aDestLen = (uint32_t) (*aDestLength);
   const char *in, *inend;
   inend = aSrc + aSrcLen;
   char16_t *out, *outend;
   outend = aDest + aDestLen;
   nsresult res = NS_OK; // conversion result
   out = aDest;
   if (mState == 0xFF) {
     // Emit supplementary character left over from previous iteration. It is
     // caller's responsibility to keep a sufficient buffer.
     if (aDestLen < 2) {
       *aSrcLength = *aDestLength = 0;
       return NS_OK_UDEC_MOREOUTPUT;
     }
     out = EmitSurrogatePair(mUcs4, out);
     mUcs4 = 0;
     mState = 0;
     mBytes = 1;
     mFirst = false;
   }
   // alias these locally for speed
   int32_t mUcs4 = this->mUcs4;
   uint8_t mState = this->mState;
   uint8_t mBytes = this->mBytes;
   bool mFirst = this->mFirst;
   // Set mFirst to false now so we don't have to every time through the ASCII
   // branch within the loop.
   if (mFirst && aSrcLen && (0 == (0x80 & (*aSrc))))
     mFirst = false;
   for (in = aSrc; ((in < inend) && (out < outend)); ++in) {
     uint8_t c = *in;
     if (0 == mState) {
       // When mState is zero we expect either a US-ASCII character or a
       // multi-octet sequence.
       if (c < 0x80) {  // 00..7F
         int32_t max_loops = std::min(inend - in, outend - out);
         Convert_ascii_run(in, out, max_loops);
         --in; // match the rest of the cases
         mBytes = 1;
       } else if (c < 0xC2) {  // C0/C1
         // Overlong 2 octet sequence
         if (mErrBehavior == kOnError_Signal) {
           res = NS_ERROR_ILLEGAL_INPUT;
           break;
         }
         *out++ = UCS2_REPLACEMENT_CHAR;
         mFirst = false;
       } else if (c < 0xE0) {  // C2..DF
         // First octet of 2 octet sequence
         mUcs4 = c;
         mUcs4 = (mUcs4 & 0x1F) << 6;
         mState = 1;
         mBytes = 2;
       } else if (c < 0xF0) {  // E0..EF
         // First octet of 3 octet sequence
         mUcs4 = c;
         mUcs4 = (mUcs4 & 0x0F) << 12;
         mState = 2;
         mBytes = 3;
       } else if (c < 0xF5) {  // F0..F4
         // First octet of 4 octet sequence
         mUcs4 = c;
         mUcs4 = (mUcs4 & 0x07) << 18;
         mState = 3;
         mBytes = 4;
       } else {  // F5..FF
         /* Current octet is neither in the US-ASCII range nor a legal first
          * octet of a multi-octet sequence.
          */
         if (mErrBehavior == kOnError_Signal) {
           /* Return an error condition. Caller is responsible for flushing and
            * refilling the buffer and resetting state.
            */
           res = NS_ERROR_ILLEGAL_INPUT;
           break;
         }
         *out++ = UCS2_REPLACEMENT_CHAR;
         mFirst = false;
       }
     } else {
       // When mState is non-zero, we expect a continuation of the multi-octet
       // sequence
       if (0x80 == (0xC0 & c)) {
         if (mState > 1) {
           // If we are here, all possibilities are:
           // mState == 2 && mBytes == 3 ||
           // mState == 2 && mBytes == 4 ||
           // mState == 3 && mBytes == 4
           if ((mBytes == 3 && ((!mUcs4 && c < 0xA0) ||             // E0 80..9F
                                (mUcs4 == 0xD000 && c > 0x9F))) ||  // ED A0..BF
               (mState == 3 && ((!mUcs4 && c < 0x90) ||             // F0 80..8F
                                (mUcs4 == 0x100000 && c > 0x8F)))) {// F4 90..BF
             // illegal sequences or sequences converted into illegal ranges.
             in--;
             if (mErrBehavior == kOnError_Signal) {
               res = NS_ERROR_ILLEGAL_INPUT;
               break;
             }
             *out++ = UCS2_REPLACEMENT_CHAR;
             mState = 0;
             mFirst = false;
             continue;
           }
         }
         // Legal continuation.
         uint32_t shift = (mState - 1) * 6;
         uint32_t tmp = c;
         tmp = (tmp & 0x0000003FL) << shift;
         mUcs4 |= tmp;
         if (0 == --mState) {
           /* End of the multi-octet sequence. mUcs4 now contains the final
            * Unicode codepoint to be output
            */
           if (mUcs4 > 0xFFFF) {
             // mUcs4 is in the range 0x10000 - 0x10FFFF. Output a UTF-16 pair
             if (out + 2 > outend) {
               // insufficient space left in the buffer. Keep mUcs4 for the
               // next iteration.
               mState = 0xFF;
               ++in;
               res = NS_OK_UDEC_MOREOUTPUT;
               break;
             }
             out = EmitSurrogatePair(mUcs4, out);
           } else if (UNICODE_BYTE_ORDER_MARK != mUcs4 || !mFirst) {
             // Don't output the BOM only if it is the first character
             *out++ = mUcs4;
           }
           //initialize UTF8 cache
           mUcs4  = 0;
           mState = 0;
           mBytes = 1;
           mFirst = false;
         }
       } else {
         /* ((0xC0 & c != 0x80) && (mState != 0))
          *
          * Incomplete multi-octet sequence. Unconsume this
          * octet and return an error condition. Caller is responsible
          * for flushing and refilling the buffer and resetting state.
          */
         in--;
         if (mErrBehavior == kOnError_Signal) {
           res = NS_ERROR_ILLEGAL_INPUT;
           break;
         }
         *out++ = UCS2_REPLACEMENT_CHAR;
         mState = 0;
         mFirst = false;
       }
     }
   }
   // output not finished, output buffer too short
   if ((NS_OK == res) && (in < inend) && (out >= outend))
     res = NS_OK_UDEC_MOREOUTPUT;
   // last UCS4 is incomplete, make sure the caller
   // returns with properly aligned continuation of the buffer
   if ((NS_OK == res) && (mState != 0))
     res = NS_OK_UDEC_MOREINPUT;
   *aSrcLength = in - aSrc;
   *aDestLength = out - aDest;
   this->mUcs4 = mUcs4;
   this->mState = mState;
   this->mBytes = mBytes;
   this->mFirst = mFirst;
   return(res);
 }

The Tor Browser / annotate

intl/uconv/src/nsUTF8ToUnicode.cpp@6474c204b198 (annotated)

intl/uconv/src/nsUTF8ToUnicode.cpp