Also: rewrite some text describing the /etc/hostid file, so that
this location is referred to just once on the page.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The interfaces documented in this page are purely glibc.
Reported-by: Colin Watson <cjwatson@ubuntu.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
http://sourceware.org/bugzilla/show_bug.cgi?id=7075
Some existing code relies on techniques like the following to
append text to a buffer:
$ cat s.c
#include <stdio.h>
char buf[80] = "not ";
main()
{
sprintf(buf, "%sfail", buf);
puts(buf);
return 0;
}
$ cc s.c
$ ./a.out
not fail
However, the standards say the results are undefined if source
and destination buffers overlap, and with suitable compiler
options, recent changes can cause unexpected results:
$ cc -v 2>&1 | grep gcc
gcc version 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036] (SUSE Linux)
$ cc -D_FORTIFY_SOURCE -O2 s.c
$ ./a.out
fail
Reported-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
It behaved this way at least since "Sun Oct 18 15:02:11 1998 +0000",
some four months after including the nscd implementation in glibc. But
there does seem to be a short window between glibc-2.1 and glibc-2.1.3
when nscd -i was not available, I don't think it's worth muddling the
point of the page with that, though.
Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Glibc's bindresvport() takes no notice of sin->sin_port:
it always returns an arbitrary reserved port in the
anonymous range (512-1023). (Reported by Mats Wichmann.)
Also:
* Add EADDRINUSE and EACCES errors.
* Mention use of getsockname(2).
* Other minor rewrites and reorderings of the text.
* Explicitly note that glib's bindresvport() ignores
sin->sin_port.
* Change license There's now virtually no text remaining from
the 1.70 version of this page.
Reported-by: Mats Wichmann <mats.d.wichmann@intel.com>
Reviewed-by: Mats Wichmann <mats.d.wichmann@intel.com>
Reviewed-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Clean up the $LANGUAGE description, by removing bogus comments
from setlocale(3) and expanding the mention in locale(7).
Maybe you will decide that a more detailed description should be left
to the gettext(3) documentation, but I actually care about the invisible
part of the patch more since the comments have put me off the track
initially ($LANGUAGE has nothing to do with setlocale(3) and is
completely isolated to gettext, as obvious from the glibc sources).
Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
dladdr() will act unexpectedly if called from non-pic code on a
compile-time-generated function pointer:
/* test_dladdr.c */
#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdio.h>
int
main(void)
{
void *func;
Dl_info info = {};
func = printf;
dladdr(func, &info);
printf("%s at %p resolved from %s\n", info.dli_sname,
func, info.dli_fname);
return 0;
}
$ cc test_dladdr.c -ldl
$ ./a.out
printf at 0x804838c resolved from ./a.out
$ cc -fPIC test_dladdr.c -ldl
$ ./a.out
_IO_printf at 0xb7f71c30 resolved from /lib/libc.so.6
In the long term, it might make sense to make dladdr() recognize
plt pointers and recurse, but I'm too afraid of Ulrich ;-)
(and he seems to be heavy proponent of pic code anyway, so
the chances for that to be accepted probably aren't high).
Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk