diff options
Diffstat (limited to 'common/stream.cpp')
| -rw-r--r-- | common/stream.cpp | 38 |
1 files changed, 29 insertions, 9 deletions
diff --git a/common/stream.cpp b/common/stream.cpp index 85647bfe3a..f49603c882 100644 --- a/common/stream.cpp +++ b/common/stream.cpp @@ -342,7 +342,7 @@ uint32 BufferedReadStream::read(void *dataPtr, uint32 dataSize) { return alreadyRead + dataSize; } -} // End of nameless namespace +} // End of anonymous namespace ReadStream *wrapBufferedReadStream(ReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) { @@ -379,12 +379,25 @@ BufferedSeekableReadStream::BufferedSeekableReadStream(SeekableReadStream *paren bool BufferedSeekableReadStream::seek(int32 offset, int whence) { // If it is a "local" seek, we may get away with "seeking" around // in the buffer only. - // Note: We could try to handle SEEK_END and SEEK_SET, too, but - // since they are rarely used, it seems not worth the effort. _eos = false; // seeking always cancels EOS - if (whence == SEEK_CUR && (int)_pos + offset >= 0 && _pos + offset <= _bufSize) { - _pos += offset; + int relOffset = 0; + switch (whence) { + case SEEK_SET: + relOffset = offset - pos(); + break; + case SEEK_CUR: + relOffset = offset; + break; + case SEEK_END: + relOffset = (size() + offset) - pos(); + break; + default: + break; + } + + if ((int)_pos + relOffset >= 0 && _pos + relOffset <= _bufSize) { + _pos += relOffset; // Note: we do not need to reset parent's eos flag here. It is // sufficient that it is reset when actually seeking in the parent. @@ -393,14 +406,21 @@ bool BufferedSeekableReadStream::seek(int32 offset, int whence) { // just seek normally in the parent stream. if (whence == SEEK_CUR) offset -= (_bufSize - _pos); - _pos = _bufSize; + // We invalidate the buffer here. This assures that successive seeks + // do not have the chance to incorrectly think they seeked back into + // the buffer. + // Note: This does not take full advantage of the buffer. But it is + // a simple way to prevent nasty errors. It would be possible to take + // full advantage of the buffer by saving its actual start position. + // This seems not worth the effort for this seemingly uncommon use. + _pos = _bufSize = 0; _parentStream->seek(offset, whence); } return true; } -} // End of nameless namespace +} // End of anonymous namespace SeekableReadStream *wrapBufferedSeekableReadStream(SeekableReadStream *parentStream, uint32 bufSize, DisposeAfterUse::Flag disposeParentStream) { if (parentStream) @@ -482,7 +502,7 @@ public: }; -} // End of nameless namespace +} // End of anonymous namespace WriteStream *wrapBufferedWriteStream(WriteStream *parentStream, uint32 bufSize) { if (parentStream) @@ -490,4 +510,4 @@ WriteStream *wrapBufferedWriteStream(WriteStream *parentStream, uint32 bufSize) return 0; } -} // End of namespace Common +} // End of namespace Common |