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Re: another stdio patch for UnixWare
From: |
Tim Rice |
Subject: |
Re: another stdio patch for UnixWare |
Date: |
Mon, 12 Oct 2020 17:00:51 -0700 (PDT) |
User-agent: |
Alpine 2.11 (UW2 23 2013-08-11) |
Hi Bruno,
On Sun, 11 Oct 2020, Bruno Haible wrote:
> What did you mean by "best not to use __base on these platforms",
> when 4 lines below, the code does
> # define _base __base
The define is because the FILE structure does have __base but not _base.
Now the comment next that member says /* the buffer (not really) */
This snip from an 2009 e-mail exchange with a SCO engineer about
GNU m4 1.4.12 may shed light on the "not really" comment.
....
Anything with the expression:
fp->__ptr - fp__base
is wrong. __base is a pointer to a hidden structure that contains
FILE details including the beginning of the
buffer. It is hidden so that SCO/USL is free to change the internal
implementation with a rev of libc.so.1 and
not break everything out there......
....
Perhaps the warning I used could have been worded better but that
was the best I could come up with at the time.
--
Tim Rice Multitalents
tim@multitalents.net