Please re-read Bug #185.

If it is the correct behaviour to write crap to the end of
file when there are backslashes in the string then you need
your head examined.

For those people who care:

The error is in functions/file.c:702
                ret = fwrite(buf,arg2->strlen,1,fp);
Change this to:
                ret = fwrite(buf,strlen(buf),1,fp);

When magic quotes are on, the input string as copied to a temporaty bufer
called buf and has the backslashes stripped. This may result
in the line becoming shorter than the input line.
Because arg2->strlen is not updated too many characters are written
to the file.
This fix may break the use of binary data in srings.