Вопрос по python – Разбор большого (20 ГБ) текстового файла с python - чтение в 2 строки как 1
Now, the explanation of the bug; it's not easy to reproduce because it depends both on the internal FILE buffer size and the number of chars passed to fread(). In the Microsoft CRT source code, in open.c, there is a block starting with this encouraging comment "This is the hard part. We found a CR at end of buffer. We must peek ahead to see if next char is an LF." Oddly, there is an almost exact copy of this function in Perl source code: http://perl5.git.perl.org/perl.git/blob/4342f4d6df6a7dfa22a470aa21e54a5622c009f3:/win32/win32.c#l3668 The problem is in the call to SetFilePointer(), used to step back one position after the lookahead; it will fail because it is unable to return the current position in a 32bit DWORD. [The fix is easy; do you see it?] At this point, the function thinks that the next read() will return the LF, but it won't because the file pointer was not moved back.
But note that Python 3.x is not affected (raw files are always opened in binary mode and CRLF translation is done by Python); with 2.7, you may use io.open().