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Require a C99-compliant snprintf(), and remove related workarounds.

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Since our substitute snprintf now returns a C99-compliant result,
there's no need anymore to have complicated code to cope with pre-C99
behavior.  We can just make configure substitute snprintf.c if it finds
that the system snprintf() is pre-C99.  (Note: I do not believe that
there are any platforms where this test will trigger that weren't
already being rejected due to our other C99-ish feature requirements for
snprintf.  But let's add the check for paranoia's sake.)  Then, simplify
the call sites that had logic to cope with the pre-C99 definition.

I also dropped some stuff that was being paranoid about the possibility
of snprintf overrunning the given buffer.  The only reports we've ever
heard of that being a problem were for Solaris 7, which is long dead,
and we've sure not heard any reports of these assertions triggering in
a long time.  So let's drop that complexity too.

Likewise, drop some code that wasn't trusting snprintf to set errno
when it returns -1.  That would be not-per-spec, and again there's
no real reason to believe it is a live issue, especially not for
snprintfs that pass all of configure's feature checks.

Discussion: https://postgr.es/m/17245.1534289329@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2018-08-16 13:01:09 -04:00
parent 1eb9221585
commit e1d19c902e
6 changed files with 125 additions and 123 deletions
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46
configure vendored
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@ -16142,7 +16142,7 @@ fi
# Run tests below here
# --------------------
# Force use of our snprintf if system's doesn't do arg control
# For NLS, force use of our snprintf if system's doesn't do arg control.
# See comment above at snprintf test for details.
if test "$enable_nls" = yes -a "$pgac_need_repl_snprintf" = no; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether snprintf supports argument control" >&5
@ -16436,6 +16436,50 @@ $as_echo "$pgac_cv_snprintf_size_t_support" >&6; }
fi
fi
# Force use of our snprintf if the system's doesn't handle buffer overrun
# as specified by C99.
if test "$pgac_need_repl_snprintf" = no; then
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether snprintf reports buffer overrun per C99" >&5
$as_echo_n "checking whether snprintf reports buffer overrun per C99... " >&6; }
if ${pgac_cv_snprintf_c99_result+:} false; then :
$as_echo_n "(cached) " >&6
else
if test "$cross_compiling" = yes; then :
pgac_cv_snprintf_c99_result=cross
else
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <stdio.h>
#include <string.h>
int main()
{
char buf[10];
if (snprintf(buf, sizeof(buf), "12345678901234567890") != 20)
return 1;
return 0;
}
_ACEOF
if ac_fn_c_try_run "$LINENO"; then :
pgac_cv_snprintf_c99_result=yes
else
pgac_cv_snprintf_c99_result=no
fi
rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
conftest.$ac_objext conftest.beam conftest.$ac_ext
fi
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_snprintf_c99_result" >&5
$as_echo "$pgac_cv_snprintf_c99_result" >&6; }
if test "$pgac_cv_snprintf_c99_result" != yes; then
pgac_need_repl_snprintf=yes
fi
fi
# Now we have checked all the reasons to replace snprintf
if test $pgac_need_repl_snprintf = yes; then