[Python-talk] {Python-talk] Running off the end of a file during read?

[Bruce Labitt]

Folks, I have been coding a binary datalog file reader for a colleague 
of mine in the UK.  He bought a really cool RS232 datalogger that he 
managed to hook up to an ECU (engine control unit).   I do a  read(56) 
because  I am looking for a particular sequence.  My method works ok for 
a file that contains multiple sessions, but fails on the last session (I 
suspect) or on a file with ony one session.

Basically I read 56 bytes then look for a sequence in it.  If I don't 
find it I reset the file pointer so that it is incremented by 1 from the 
start of the last 56 byte read.  The program keeps going until it finds 
the right sequence. 

Obviously, if either the sequence is not there, or one hits end of file 
things would go haywire (program hang in my case).

Does f.read(n) error if the function hits eof?  If not how can I 
determine when I hit eof?

Thanks,
Bruce