+ // file should be opened
+ wxASSERT_MSG( m_file.IsOpened(), wxT("can't read closed file") );
+
+ // read the entire file in memory: this is not the most efficient thing to
+ // do it but there is no good way to avoid it in Unicode build because if
+ // we read the file block by block we can't convert each block to Unicode
+ // separately (the last multibyte char in the block might be only partially
+ // read and so the conversion would fail) and, as the file contents is kept
+ // in memory by wxTextFile anyhow, it shouldn't be a big problem to read
+ // the file entirely
+ size_t bufSize = 0;
+
+ // number of bytes to (try to) read from disk at once
+ static const size_t BLOCK_SIZE = 4096;
+
+ wxCharBuffer buf;
+
+ // first determine if the file is seekable or not and so whether we can
+ // determine its length in advance
+ wxFileOffset fileLength;
+ {
+ wxLogNull logNull;
+ fileLength = m_file.Length();
+ }
+
+ // some non-seekable files under /proc under Linux pretend that they're
+ // seekable but always return 0; others do return an error
+ const bool seekable = fileLength != wxInvalidOffset && fileLength != 0;
+ if ( seekable )
+ {
+ // we know the required length, so set the buffer size in advance
+ bufSize = fileLength;
+ if ( !buf.extend(bufSize) )
+ return false;
+
+ // if the file is seekable, also check that we're at its beginning
+ wxASSERT_MSG( m_file.Tell() == 0, wxT("should be at start of file") );
+
+ char *dst = buf.data();
+ for ( size_t nRemaining = bufSize; nRemaining > 0; )
+ {
+ size_t nToRead = BLOCK_SIZE;
+
+ // the file size could have changed, avoid overflowing the buffer
+ // even if it did
+ if ( nToRead > nRemaining )
+ nToRead = nRemaining;
+
+ ssize_t nRead = m_file.Read(dst, nToRead);
+
+ if ( nRead == wxInvalidOffset )
+ {
+ // read error (error message already given in wxFile::Read)
+ return false;
+ }
+
+ if ( nRead == 0 )
+ {
+ // this file can't be empty because we checked for this above
+ // so this must be the end of file
+ break;
+ }
+
+ dst += nRead;
+ nRemaining -= nRead;
+ }
+
+ wxASSERT_MSG( dst - buf.data() == (wxFileOffset)bufSize,
+ wxT("logic error") );
+ }
+ else // file is not seekable
+ {
+ char block[BLOCK_SIZE];
+ for ( ;; )
+ {
+ ssize_t nRead = m_file.Read(block, WXSIZEOF(block));
+
+ if ( nRead == wxInvalidOffset )
+ {
+ // read error (error message already given in wxFile::Read)
+ return false;
+ }
+
+ if ( nRead == 0 )
+ {
+ // if no bytes have been read, presumably this is a
+ // valid-but-empty file
+ if ( bufSize == 0 )
+ return true;
+
+ // otherwise we've finished reading the file
+ break;
+ }
+
+ // extend the buffer for new data
+ if ( !buf.extend(bufSize + nRead) )
+ return false;
+
+ // and append it to the buffer
+ memcpy(buf.data() + bufSize, block, nRead);
+ bufSize += nRead;
+ }
projects / wxWidgets.git / blobdiff