EOF for binary?

[flamesrock]

Hi,

So if I understand correctly, there are NO eof characters in any binary
file. If so, is there an easier way to check for the end of the file
than:

os.path.getsize (infile) <= infile.tell()

Because that returns the error:
# File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
# return os.stat(filenam e).st_size
#TypeError: coercing to Unicode: need string or buffer, file found
for me.


-thanks in advance
flamesrock

[Roy Smith]

Re: EOF for binary?

In article <1105147072.909 665.242360@z14g 2000cwz.googleg roups.com>,
"flamesrock " <flamesrock@gma il.com> wrote:
[color=blue]
> Hi,
>
> So if I understand correctly, there are NO eof characters in any binary
> file. If so, is there an easier way to check for the end of the file
> than:
>
> os.path.getsize (infile) <= infile.tell()[/color]

How you detect EOF depends on how you're reading the file. For example,
read() indicates EOF by returning fewer characters than you asked for
(possibly zero).

Checking the length of a file is perilous. Files change size. File
sizes don't have much meaning on things like network sockets to begin
with.

[flamesrock]

Re: EOF for binary?

Thanks!

I don't know why, but the most innefficient and unmaintanable means of
doing something usually pops into my head before anything else. I
solved this by going

elif len(header) < 8:
break

[Marc 'BlackJack' Rintsch]

Re: EOF for binary?

In <1105147072.909 665.242360@z14g 2000cwz.googleg roups.com>, flamesrock
wrote:
[color=blue]
> os.path.getsize (infile) <= infile.tell()
>
> Because that returns the error:
> # File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
> # return os.stat(filenam e).st_size
> #TypeError: coercing to Unicode: need string or buffer, file found
> for me.[/color]

This error message gives a good hint what's wrong with your code snippet.
[color=blue][color=green][color=darkred]
>>> f = open('tmp.txt')
>>> os.path.getsize (f)[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
return os.stat(filenam e).st_size
TypeError: coercing to Unicode: need string or buffer, file found

Something expected a string instead of a file object.
[color=blue][color=green][color=darkred]
>>> os.path.getsize ("tmp.txt")[/color][/color][/color]
28190L

Ciao,
Marc 'BlackJack' Rintsch

[Dennis Lee Bieber]

Re: EOF for binary?

On 7 Jan 2005 17:17:52 -0800, "flamesrock " <flamesrock@gma il.com>
declaimed the following in comp.lang.pytho n:[color=blue]
>
> os.path.getsize (infile) <= infile.tell()
>
> Because that returns the error:
> # File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
> # return os.stat(filenam e).st_size
> #TypeError: coercing to Unicode: need string or buffer, file found
> for me.
>[/color]
Sounds reasonable...

infile.tell() is a method on a /file type/

os.path.getsize () wants a file-path/name. IE, it wants you to
pass it whatever you fed (the xxx) to
infile = open(xxx)

--[color=blue]
> =============== =============== =============== =============== == <
> wlfraed@ix.netc om.com | Wulfraed Dennis Lee Bieber KD6MOG <
> wulfraed@dm.net | Bestiaria Support Staff <
> =============== =============== =============== =============== == <
> Home Page: <http://www.dm.net/~wulfraed/> <
> Overflow Page: <http://wlfraed.home.ne tcom.com/> <[/color]

[flamesrock]

Re: EOF for binary?

ahh..that does make sense. But maybe getsize() should have a way of
inferring what file is specified. I might actually submit a request..

[Dennis Lee Bieber]

Re: EOF for binary?

On 8 Jan 2005 14:47:34 -0800, "flamesrock " <flamesrock@gma il.com>
declaimed the following in comp.lang.pytho n:
[color=blue]
> ahh..that does make sense. But maybe getsize() should have a way of
> inferring what file is specified. I might actually submit a request..[/color]

But then it should be a method of file, not of os.path

ie:
infile = open(my_file_na me)
sz = infile.getsize( )

os.path is primarily concerned with directory
information, not with the contents of an open file. {Though on LS-DOS,
the C file pointer structure ended up in dual use... somehow, when the
file is open, it held read/write pointers, etc. but when closed the
filename was stuffed back into it <G>}

--[color=blue]
> =============== =============== =============== =============== == <
> wlfraed@ix.netc om.com | Wulfraed Dennis Lee Bieber KD6MOG <
> wulfraed@dm.net | Bestiaria Support Staff <
> =============== =============== =============== =============== == <
> Home Page: <http://www.dm.net/~wulfraed/> <
> Overflow Page: <http://wlfraed.home.ne tcom.com/> <[/color]