Re: read() MAX_IO_SIZE bytes, more than SSIZE_MAX?

From: Joachim Schmitz <jojo@schmitz-digital.de>
Date: Feb 8, 2015, 12:05 UTC
Message-ID: <loom.20150208T125055-287@post.gmane.org>
In-Reply-To: <CAPc5daXD_7XZD5Vag51BjrSZ0q1r9eMswhLmnpUFqqjrc9oSTw@mail.gmail.com>

Junio C Hamano <gitster <at> pobox.com> writes:

<snip>

Show 14 quoted lines

> >
> > something like this:
> >
> > /* allow overwriting from e.g. Makefile */
> > #if !defined(MAX_IO_SIZE)
> > # define MAX_IO_SIZE (8*1024*1024)
> > #endif
> > /* for plattforms that have SSIZE and have it smaller */
> > #if defined(SSIZE_MAX && (SSIZE_MAX < MAX_IO_SIZE)
> > # undef MAX_IO_SIZE /* avoid warning */
> > # define MAX_IO_SIZE SSIZE_MAX
> > #endif
> 
> No, not like that. If you do (1), that is only so that the Makefile can

override

Show 6 quoted lines

> a broken definition a platform may give to SSIZE_MAX.  So
> 
>  (1) if Makefile gives one, use it without second-guessing with SSIZE_MAX.
>  (2) if SSIZE_MAX is defined, and if it is smaller than our internal
> default, use it.
>  (3) all other cases, us our internal default.

oops, yes, of course

/* allow overwriting from e.g. Makefile */
#ifndef(MAX_IO_SIZE)
# define MAX_IO_SIZE (8*1024*1024)
  /* for plattforms that have SSIZE and have it smaller */
# if defined(SSIZE_MAX) && (SSIZE_MAX < MAX_IO_SIZE)
#  undef MAX_IO_SIZE /* avoid warning */
#  define MAX_IO_SIZE SSIZE_MAX
# endif
#endif