Glenn, why can not _GNU_SOURCE be set when iffe finds it runs on
Linux? It will enable a lot of missing or useful apis.
Yes, Linux is bound to honor POSIX and SUS when they can. Their
problem is that they usually have no access to the test suite and do
not fully partake in Opengroup, which leads to some cancer growing
until it is put down by Linus or others.
Olga
On Wed, Jul 18, 2012 at 5:01 PM, Glenn Fowler <g...@research.att.com> wrote:
>
> these new iffe probes look good
> my first hack at *at() will be to redo ast fts (which is the base for all ast
> dir traversal)
> based on that the probes/macros may change in order
> to make the *at() vs !*at() coding as readable/portable as possible
>
> re _GNU_SOURCE:
>
> its hard enough to coax the latest posix apis out of cc
> getting each os implementation to reveal extensions is even more interesting
> so most of the *_SOURCE dancing is done in the libast implementation and does
> not leak out in *.h
> with the exception of { _LARGEFILE64_SOURCE _LARGEFILE_SOURCE }
>
> grabbing the O_PATH value in iffe and using it for O_search will probably be
> a necessary evil
>
> re posix compatibility: is linux concerned with that anymore?
>
> On Wed, 18 Jul 2012 10:12:05 +0200 Josh Hurst wrote:
>> On Wed, Jul 18, 2012 at 7:22 AM, Roland Mainz <roland.ma...@nrubsig.org>
>> wrote:
>> > On Mon, Jul 9, 2012 at 9:48 AM, Roland Mainz <roland.ma...@nrubsig.org>
>> > wrote:
>> > [snip]
>> >> - The patch relies on |O_SEARCH| which was added with XPG7. Since
>> >> previous XPG versions did not have that test in the shell testsuite we
>> >> happily assume that only platforms implementing |O_SEARCH| must be
>> >> able to conform to that test (all major Unix versions have |O_SEARCH|
>> >> in their current versions since at least two years).
>> >>
>> >> - The patch could in theory use Linux's |O_PATH| ... but as we
>> >> discovered by accident in
>> >> https://mailman.research.att.com/pipermail/ast-developers/2012q3/001512.html
>> >> |O_PATH| currently does not work in Linux3.0 with |fchdir()|. However
>> >> Linus did us a *BIG* favor and pushed ASAP a patch (see
>> >> http://marc.info/?l=git-commits-head&m=134170760505086&w=2) and marked
>> >> it for inclusion into the 3.x stable branch, e.g. most Linux
>> >> distributions running the 3.x kernel series will pick it up quickly
>> >> (within less than a couple of months). Once we have a machine with
>> >> |O_PATH| fixed we can revisit the issue... but we need a iffe probe
>> >> then (the current patch explicitly works without iffe probes).
>> >
>> > One request:
>> > Can we have three new iffe probes for ksh93v-, please:
>> > 1. One iffe probe which sets a CPP symbol |O_search| when either...
>> > a) ... |O_SEARCH| is defined (Solaris 11 (maybe 10, too), AIX7, etc.)
>> > ... or...
>> > b) ... |O_PATH| is defined and passes the following test from Olga
>> > (please replace s/O_SEARCH/O_PATH/):
>> > -- snip --
>
>> Add #define _GNU_SOURCE 1 here.
>
>> > #include <sys/types.h>
>> > #include <sys/stat.h>
>> > #include <fcntl.h>
>> > #include <unistd.h>
>> >
>> > #include <stdlib.h>
>> > #include <stdio.h>
>> >
>> > int main(int ac, char *av[])
>> > {
>> > int dirfd, dupdirfd;
>> >
>> > dirfd=open("/etc", O_SEARCH);
>> > if(dirfd<0)
>> > {
>> > fprintf(stderr, "open() failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > dupdirfd = fcntl(dirfd, F_DUPFD, 50);
>> > if(dirfd<0)
>> > {
>> > fprintf(stderr, "fcntl() failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > if(fchdir(dupdirfd)<0)
>> > {
>> > fprintf(stderr, "fchdir(dupdirfd) failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > if(fchdir(dirfd)<0)
>> > {
>> > fprintf(stderr, "fchdir(dirfd) failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > if(openat(dupdirfd, "profile", O_RDONLY)<0)
>> > {
>> > fprintf(stderr, "openat(dupdirfd, profile, O_RDONLY)
>> > failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > dirfd=openat(dupdirfd, "krb5", O_SEARCH);
>
>> Replace "krb5" with "X11", Linux has no /etc/krb5 directory.
>
>> > if(dirfd<0)
>> > {
>> > fprintf(stderr, "openat(dupdirfd, krb5, O_SEARCH)
>> > failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > if(fchdir(dirfd)<0)
>> > {
>> > fprintf(stderr, "2nd fchdir(dirfd) failed.\n");
>> > return EXIT_FAILURE;
>> > }
>> >
>> > puts("SUCCESS.");
>> >
>> > return EXIT_SUCCESS;
>> > }
>> > -- snip --
>> > Using |O_SEARCH| for |O_search| should be preferred over |O_PATH| if
>> > both are available.
>
>> I think a iffe script would be good since the Linux header require
>> _GNU_SOURCE to be defined or O_PATH is not defined. IMO the iffe
>> script should extract the value for O_PATH (which can differ between
>> architectures, i.e. SPARC uses a different bit value than x86-64) and
>> make it available as O_search if O_SEARCH is not defined.
>
>> Josh
>
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--
, _ _ ,
{ \/`o;====- Olga Kryzhanovska -====;o`\/ }
.----'-/`-/ olga.kryzhanov...@gmail.com \-`\-'----.
`'-..-| / http://twitter.com/fleyta \ |-..-'`
/\/\ Solaris/BSD//C/C++ programmer /\/\
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