On 2013-03-15 6:13 AM, Thomas Jahns wrote:
On 03/15/2013 02:19 AM, Zack Weinberg wrote:
I've been doing research into the cross-platform availability of
header files that are commonly probed for in Autoconf scripts.
Results so far are here:
http://www.owlfolio.org/possibly-useful/notes-on-the-cross-platform-availability-of-header-files/
Based on what I've learned, I have some questions for y'all:
although you didn't ask: aio.h does not need to be probed for: unistd.h defines
_POSIX_ASYNCHRONOUS_IO when it's available.
See <http://pubs.opengroup.org/onlinepubs/007904875/basedefs/unistd.h.html> for
some other features that don't require autoconf to check for, sys/mman.h is in
the same category.
As Ralf pointed out, this mechanism is not reliable in practice.
With respect to your comment on identifiers with leading underscore: to be
conformant to e.g. C89 standards, an implementation must not define anything
without said leading underscore, but in cases where the non-standard
functionality is required to implement standard-mandated functionality, it's
easiest to have it available with a leading underscore.
The rule you cite applies only to headers that are part of C89, which
e.g. <fcntl.h> isn't. However, yes, this may have been what the folks
at MS were thinking back in the 1990s when they made their <fcntl.h> not
actually define what POSIX says it's supposed to define.
In case you still need it, I could check AIX 6.1 for any header you want to know
about or provide an ls -R of /usr/include
Yes, please. (Do I understand correctly that AIX 7 is the latest and
greatest in that line? This test is actually more interesting when
applied to older systems, as they define the baseline.)
The exact command you should run is
$ find /usr/include \( -type f -a -name \*.h \) -print |
sed s:/usr/include/:: | LC_ALL=C sort > headers-$(uname)-$(uname -r)
Don't worry about headers coming from third party libraries, I have
scripts for that.
zw
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