Make our usage of memset_s() conform strictly to the C11 standard.

Per the letter of the C11 standard, one must #define
__STDC_WANT_LIB_EXT1__ as 1 before including  in order to
have access to memset_s().  It appears that many platforms are lenient
about this, because we weren't doing it and yet the code appeared to
work anyway.  But we now find that with -std=c11, macOS is strict and
doesn't declare memset_s, leading to compile failures since we try to
use it anyway.  (Given the lack of prior reports, perhaps this is new
behavior in the latest SDK?  No matter, we're clearly in the wrong.)

In addition to the immediate problem, which could be fixed merely by
adding the needed #define to explicit_bzero.c, it seems possible that
our configure-time probe for memset_s() could fail in case a platform
implements the function in some odd way due to this spec requirement.
This concern can be fixed in largely the same way that we dealt with
strchrnul() in 6da2ba1d8: switch to using a declaration-based
configure probe instead of a does-it-link probe.

Back-patch to v13 where we started using memset_s().

Reported-by: Lakshmi Narayana Velayudam 
Author: Tom Lane 
Discussion: https://postgr.es/m/CAA4pTnLcKGG78xeOjiBr5yS7ZeE-Rh=FaFQQGOO=nPzA1L8yEA@mail.gmail.com
Backpatch-through: 13

diff --git a/configure b/configure
index 275c67ee67c97fc32ba5b8f862133e246d334594..4f15347cc95031440ac5693cc4c59b9abfa43c23 100755 (executable)
--- a/configure
+++ b/configure
@@ -15616,7 +15616,7 @@ fi
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-for ac_func in backtrace_symbols copyfile copy_file_range elf_aux_info getauxval getifaddrs getpeerucred inet_pton kqueue localeconv_l mbstowcs_l memset_s posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strsignal syncfs sync_file_range uselocale wcstombs_l
+for ac_func in backtrace_symbols copyfile copy_file_range elf_aux_info getauxval getifaddrs getpeerucred inet_pton kqueue localeconv_l mbstowcs_l posix_fallocate ppoll pthread_is_threaded_np setproctitle setproctitle_fast strsignal syncfs sync_file_range uselocale wcstombs_l
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
@@ -16192,6 +16192,19 @@ cat >>confdefs.h <<_ACEOF
 #define HAVE_DECL_STRCHRNUL $ac_have_decl
 _ACEOF
 
+ac_fn_c_check_decl "$LINENO" "memset_s" "ac_cv_have_decl_memset_s" "#define __STDC_WANT_LIB_EXT1__ 1
+#include 
+"
+if test "x$ac_cv_have_decl_memset_s" = xyes; then :
+  ac_have_decl=1
+else
+  ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_MEMSET_S $ac_have_decl
+_ACEOF
+
 
 # This is probably only present on macOS, but may as well check always
 ac_fn_c_check_decl "$LINENO" "F_FULLFSYNC" "ac_cv_have_decl_F_FULLFSYNC" "#include 

diff --git a/configure.ac b/configure.ac
index 7ea91d56adb83f0c940b696e938c638e51c4d7f8..4b8335dc6138e4e6c52931e44ac06407f0029944 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1792,7 +1792,6 @@ AC_CHECK_FUNCS(m4_normalize([
    kqueue
    localeconv_l
    mbstowcs_l
-   memset_s
    posix_fallocate
    ppoll
    pthread_is_threaded_np
@@ -1838,6 +1837,8 @@ AC_CHECK_DECLS([strlcat, strlcpy, strnlen, strsep, timingsafe_bcmp])
 AC_CHECK_DECLS([preadv], [], [], [#include ])
 AC_CHECK_DECLS([pwritev], [], [], [#include ])
 AC_CHECK_DECLS([strchrnul], [], [], [#include ])
+AC_CHECK_DECLS([memset_s], [], [], [#define __STDC_WANT_LIB_EXT1__ 1
+#include ])
 
 # This is probably only present on macOS, but may as well check always
 AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include ])

diff --git a/meson.build b/meson.build
index 12de5e80c3144c3f43c35018395c9cb5986f0358..d142e3e408b385e4a85ec29f1c8a49e89f506f89 100644 (file)
--- a/meson.build
+++ b/meson.build
@@ -2654,6 +2654,7 @@ decl_checks += [
   ['preadv', 'sys/uio.h'],
   ['pwritev', 'sys/uio.h'],
   ['strchrnul', 'string.h'],
+  ['memset_s', 'string.h', '#define __STDC_WANT_LIB_EXT1__ 1'],
 ]
 
 # Check presence of some optional LLVM functions.
@@ -2667,21 +2668,23 @@ endif
 foreach c : decl_checks
   func = c.get(0)
   header = c.get(1)
-  args = c.get(2, {})
+  prologue = c.get(2, '')
+  args = c.get(3, {})
   varname = 'HAVE_DECL_' + func.underscorify().to_upper()
 
   found = cc.compiles('''
-#include <@0@>
+@0@
+#include <@1@>
 
 int main()
 {
-#ifndef @1@
-    (void) @1@;
+#ifndef @2@
+    (void) @2@;
 #endif
 
 return 0;
 }
-'''.format(header, func),
+'''.format(prologue, header, func),
     name: 'test whether @0@ is declared'.format(func),
     # need to add cflags_warn to get at least
     # -Werror=unguarded-availability-new if applicable
@@ -2880,7 +2883,6 @@ func_checks = [
   ['kqueue'],
   ['localeconv_l'],
   ['mbstowcs_l'],
-  ['memset_s'],
   ['mkdtemp'],
   ['posix_fadvise'],
   ['posix_fallocate'],

diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index c3cc9fa856dfc839789fc30fff2db975884df6ef..726a7c1be1f4da1ee64259e28525690a5979ae8c 100644 (file)
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -91,6 +91,10 @@
    `LLVMCreatePerfJITEventListener', and to 0 if you don't. */
 #undef HAVE_DECL_LLVMCREATEPERFJITEVENTLISTENER
 
+/* Define to 1 if you have the declaration of `memset_s', and to 0 if you
+   don't. */
+#undef HAVE_DECL_MEMSET_S
+
 /* Define to 1 if you have the declaration of `posix_fadvise', and to 0 if you
    don't. */
 #undef HAVE_DECL_POSIX_FADVISE
@@ -291,9 +295,6 @@
 /* Define to 1 if you have the  header file. */
 #undef HAVE_MEMORY_H
 
-/* Define to 1 if you have the `memset_s' function. */
-#undef HAVE_MEMSET_S
-
 /* Define to 1 if you have the `mkdtemp' function. */
 #undef HAVE_MKDTEMP
 

diff --git a/src/port/explicit_bzero.c b/src/port/explicit_bzero.c
index 1d37b119bab1347c3764b9357fb15adf36c7d5f6..53766e86e940d6c147eeb48fd8f87af51d91845f 100644 (file)
--- a/src/port/explicit_bzero.c
+++ b/src/port/explicit_bzero.c
@@ -12,9 +12,11 @@
  *-------------------------------------------------------------------------
  */
 
+#define __STDC_WANT_LIB_EXT1__ 1   /* needed to access memset_s() */
+
 #include "c.h"
 
-#if defined(HAVE_MEMSET_S)
+#if HAVE_DECL_MEMSET_S
 
 void
 explicit_bzero(void *buf, size_t len)