NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/os/linux/23187

Text File | 1993-01-08 | 1.9 KB | 43 lines

Newsgroups: comp.os.linux
Path: sparky!uunet!usc!sdd.hp.com!saimiri.primate.wisc.edu!usenet.coe.montana.edu!news.u.washington.edu!serval!luke.eecs.wsu.edu!hlu
From: [e-mail] (H.J. Lu)
Subject: Re: Library 4.1 bug/feature?  fopen("fifo","a") fails
Message-ID: <[e-mail]>
Sender: [e-mail] (USENET News System)
Organization: Washington State University!
References: <[e-mail]> <[e-mail]> <[e-mail]>
Date: Fri, 8 Jan 93 07:23:23 GMT
Lines: 31

In article <[e-mail]> [e-mail] (Doug Quale) writes:
>In article <[e-mail]> [e-mail] (H.J. Lu) writes:
>>In article <[e-mail]> [e-mail] writes:
>>>Is it a bug or a feature that fopen("fifo","a"), where "fifo" is a named
>>>pipe, fails with an 'illegal lseek' in the 4.1 version of the library?
>>>The opinion on comp.std.unix seems to be that there should be no
>>>problem...
>>
>>That is a feature of stdio/kernel. I was told that according to ANSI
>>standard, fopen ("foo", "a") should do a lseek () to the end after
>>calling open (). But linux kernel refuses to any lseek () on
>>non-regular files.
>>
>
>If iostream works this way, it is broken, because fopen ("foo", "a")
>is *not* an open followed by an lseek.  The open must be in O_APPEND mode
>or files writen by several processes will lose horribly.
>
>To the specific point asked, I believe that lseeks are not permitted on
>pipes, named or otherwise, and so it is not a bug that Linux disallows
>O_APPEND mode on pipes.  But if iostream really does an lseek for
>fopen ("foo", "a") that should be fixed.
>--
>Doug Quale
>[e-mail]

It should be said "reverse what was done to iostream". I believe
fopen ("foo", "a") means open "foo" and set r/w pointer at the
end of the file.

H.J.