[PATCH v3 1/1] Fix detection of preadv/pwritev support for OSX.

Fixes:
gcc -Wall -Wmissing-prototypes -Wpointer-arith -Wdeclaration-after-statement -Werror=vla -Wendif-labels -Wmissing-format-attribute -Wformat-security -fno-strict-aliasing -fwrapv -Wno-unused-command-line-argument -O2 -I../../../../src/include -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk -c -o fd.o fd.c
fd.c:3661:10: warning: 'pwritev' is only available on macOS 11.0 or newer [-Wunguarded-availability-new]
part = pg_pwritev(fd, iov, iovcnt, offset);
^~~~~~~~~~
../../../../src/include/port/pg_iovec.h:49:20: note: expanded from macro 'pg_pwritev'
^~~~~~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX11.1.sdk/usr/include/sys/uio.h:104:9: note: 'pwritev' has been marked as being introduced in macOS 11.0
here, but the deployment target is macOS 10.15.0
ssize_t pwritev(int, const struct iovec *, int, off_t) __DARWIN_NOCANCEL(pwritev) __API_AVAILABLE(macos(11.0), ios(14.0), watchos(7.0), tvos(14.0));
^
fd.c:3661:10: note: enclose 'pwritev' in a __builtin_available check to silence this warning
part = pg_pwritev(fd, iov, iovcnt, offset);
^~~~~~~~~~
../../../../src/include/port/pg_iovec.h:49:20: note: expanded from macro 'pg_pwritev'
^~~~~~~
1 warning generated.

This results in a runtime error:
running bootstrap script ... dyld: lazy symbol binding failed: Symbol not found: _pwritev
Referenced from: /usr/local/pgsql/bin/postgres
Expected in: /usr/lib/libSystem.B.dylib

dyld: Symbol not found: _pwritev
Referenced from: /usr/local/pgsql/bin/postgres
Expected in: /usr/lib/libSystem.B.dylib

child process was terminated by signal 6: Abort trap: 6

To fix this we set -Werror=unguarded-availability-new so that a declaration
check for preadv/pwritev will fail if the symbol is unavailable on the requested
SDK version.
---
Changes v2 -> v3:
- Replace compile check with AC_CHECK_DECLS
- Fix preadv detection as well
Changes v1 -> v2:
- Add AC_LIBOBJ(pwritev) when pwritev not available
- set -Werror=unguarded-availability-new for CXX flags as well
---
configure | 164 ++++++++++++++++++++++++++++++------
configure.ac | 9 +-
src/include/pg_config.h.in | 14 +--
src/include/port/pg_iovec.h | 4 +-
src/tools/msvc/Solution.pm | 4 +-
5 files changed, 157 insertions(+), 38 deletions(-)

diff --git a/configure b/configure
index 8af4b99021..07a9b08d80 100755
--- a/configure
+++ b/configure
@@ -5373,6 +5373,98 @@ if test x"$pgac_cv_prog_CC_cflags__Werror_vla" = x"yes"; then
fi


+ # Prevent usage of symbols marked as newer than our target.
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Werror=unguarded-availability-new, for CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -Werror=unguarded-availability-new, for CFLAGS... " >&6; }
+if ${pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${CFLAGS} -Werror=unguarded-availability-new"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+ pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new=yes
+else
+ pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_c_werror_flag=$ac_save_c_werror_flag
+CFLAGS="$pgac_save_CFLAGS"
+CC="$pgac_save_CC"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new" >&5
+$as_echo "$pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new" >&6; }
+if test x"$pgac_cv_prog_CC_cflags__Werror_unguarded_availability_new" = x"yes"; then
+ CFLAGS="${CFLAGS} -Werror=unguarded-availability-new"
+fi
+
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CXX} supports -Werror=unguarded-availability-new, for CXXFLAGS" >&5
+$as_echo_n "checking whether ${CXX} supports -Werror=unguarded-availability-new, for CXXFLAGS... " >&6; }
+if ${pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CXXFLAGS=$CXXFLAGS
+pgac_save_CXX=$CXX
+CXX=${CXX}
+CXXFLAGS="${CXXFLAGS} -Werror=unguarded-availability-new"
+ac_save_cxx_werror_flag=$ac_cxx_werror_flag
+ac_cxx_werror_flag=yes
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new=yes
+else
+ pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+CXXFLAGS="$pgac_save_CXXFLAGS"
+CXX="$pgac_save_CXX"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new" >&5
+$as_echo "$pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new" >&6; }
+if test x"$pgac_cv_prog_CXX_cxxflags__Werror_unguarded_availability_new" = x"yes"; then
+ CXXFLAGS="${CXXFLAGS} -Werror=unguarded-availability-new"
+fi
+
+
# -Wvla is not applicable for C++

{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wendif-labels, for CFLAGS" >&5
@@ -15646,6 +15738,52 @@ cat >>confdefs.h <<_ACEOF
_ACEOF


+# AC_REPLACE_FUNCS does not respect the deployment target on macOS
+ac_fn_c_check_decl "$LINENO" "preadv" "ac_cv_have_decl_preadv" "#include <sys/uio.h>
+"
+if test "x$ac_cv_have_decl_preadv" = xyes; then :
+ ac_have_decl=1
+else
+ ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_PREADV $ac_have_decl
+_ACEOF
+if test $ac_have_decl = 1; then :
+
+else
+ case " $LIBOBJS " in
+ *" preadv.$ac_objext "* ) ;;
+ *) LIBOBJS="$LIBOBJS preadv.$ac_objext"
+ ;;
+esac
+
+fi
+
+ac_fn_c_check_decl "$LINENO" "pwritev" "ac_cv_have_decl_pwritev" "#include <sys/uio.h>
+"
+if test "x$ac_cv_have_decl_pwritev" = xyes; then :
+ ac_have_decl=1
+else
+ ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_PWRITEV $ac_have_decl
+_ACEOF
+if test $ac_have_decl = 1; then :
+
+else
+ case " $LIBOBJS " in
+ *" pwritev.$ac_objext "* ) ;;
+ *) LIBOBJS="$LIBOBJS pwritev.$ac_objext"
+ ;;
+esac
+
+fi
+
+
ac_fn_c_check_decl "$LINENO" "RTLD_GLOBAL" "ac_cv_have_decl_RTLD_GLOBAL" "#include <dlfcn.h>
"
if test "x$ac_cv_have_decl_RTLD_GLOBAL" = xyes; then :
@@ -15845,19 +15983,6 @@ esac

fi

-ac_fn_c_check_func "$LINENO" "preadv" "ac_cv_func_preadv"
-if test "x$ac_cv_func_preadv" = xyes; then :
- $as_echo "#define HAVE_PREADV 1" >>confdefs.h
-
-else
- case " $LIBOBJS " in
- *" preadv.$ac_objext "* ) ;;
- *) LIBOBJS="$LIBOBJS preadv.$ac_objext"
- ;;
-esac
-
-fi
-
ac_fn_c_check_func "$LINENO" "pwrite" "ac_cv_func_pwrite"
if test "x$ac_cv_func_pwrite" = xyes; then :
$as_echo "#define HAVE_PWRITE 1" >>confdefs.h
@@ -15871,19 +15996,6 @@ esac

fi

-ac_fn_c_check_func "$LINENO" "pwritev" "ac_cv_func_pwritev"
-if test "x$ac_cv_func_pwritev" = xyes; then :
- $as_echo "#define HAVE_PWRITEV 1" >>confdefs.h
-
-else
- case " $LIBOBJS " in
- *" pwritev.$ac_objext "* ) ;;
- *) LIBOBJS="$LIBOBJS pwritev.$ac_objext"
- ;;
-esac
-
-fi
-
ac_fn_c_check_func "$LINENO" "random" "ac_cv_func_random"
if test "x$ac_cv_func_random" = xyes; then :
$as_echo "#define HAVE_RANDOM 1" >>confdefs.h
diff --git a/configure.ac b/configure.ac
index 868a94c9ba..0cd1ee8909 100644
--- a/configure.ac
+++ b/configure.ac
@@ -494,6 +494,9 @@ if test "$GCC" = yes -a "$ICC" = no; then
AC_SUBST(PERMIT_DECLARATION_AFTER_STATEMENT)
# Really don't want VLAs to be used in our dialect of C
PGAC_PROG_CC_CFLAGS_OPT([-Werror=vla])
+ # Prevent usage of symbols marked as newer than our target.
+ PGAC_PROG_CC_CFLAGS_OPT([-Werror=unguarded-availability-new])
+ PGAC_PROG_CXX_CFLAGS_OPT([-Werror=unguarded-availability-new])
# -Wvla is not applicable for C++
PGAC_PROG_CC_CFLAGS_OPT([-Wendif-labels])
PGAC_PROG_CXX_CFLAGS_OPT([-Wendif-labels])
@@ -1705,6 +1708,10 @@ AC_CHECK_DECLS([strlcat, strlcpy, strnlen])
# This is probably only present on macOS, but may as well check always
AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include <fcntl.h>])

+# AC_REPLACE_FUNCS does not respect the deployment target on macOS
+AC_CHECK_DECLS([preadv], [], [AC_LIBOBJ(preadv)], [#include <sys/uio.h>])
+AC_CHECK_DECLS([pwritev], [], [AC_LIBOBJ(pwritev)], [#include <sys/uio.h>])
+
AC_CHECK_DECLS([RTLD_GLOBAL, RTLD_NOW], [], [], [#include <dlfcn.h>])

AC_CHECK_TYPE([struct sockaddr_in6],
@@ -1737,9 +1744,7 @@ AC_REPLACE_FUNCS(m4_normalize([
link
mkdtemp
pread
- preadv
pwrite
- pwritev
random
srandom
strlcat
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index f4d9f3b408..9c30d008c9 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -142,6 +142,14 @@
don't. */
#undef HAVE_DECL_POSIX_FADVISE

+/* Define to 1 if you have the declaration of `preadv', and to 0 if you don't.
+ */
+#undef HAVE_DECL_PREADV
+
+/* Define to 1 if you have the declaration of `pwritev', and to 0 if you
+ don't. */
+#undef HAVE_DECL_PWRITEV
+
/* Define to 1 if you have the declaration of `RTLD_GLOBAL', and to 0 if you
don't. */
#undef HAVE_DECL_RTLD_GLOBAL
@@ -412,9 +420,6 @@
/* Define to 1 if you have the `pread' function. */
#undef HAVE_PREAD

-/* Define to 1 if you have the `preadv' function. */
-#undef HAVE_PREADV
-
/* Define to 1 if you have the `pstat' function. */
#undef HAVE_PSTAT

@@ -433,9 +438,6 @@
/* Define to 1 if you have the `pwrite' function. */
#undef HAVE_PWRITE

-/* Define to 1 if you have the `pwritev' function. */
-#undef HAVE_PWRITEV
-
/* Define to 1 if you have the `random' function. */
#undef HAVE_RANDOM

diff --git a/src/include/port/pg_iovec.h b/src/include/port/pg_iovec.h
index 365d605a9b..760ec4980c 100644
--- a/src/include/port/pg_iovec.h
+++ b/src/include/port/pg_iovec.h
@@ -39,13 +39,13 @@ struct iovec
/* Define a reasonable maximum that is safe to use on the stack. */
#define PG_IOV_MAX Min(IOV_MAX, 32)

-#ifdef HAVE_PREADV
+#if HAVE_DECL_PREADV
#define pg_preadv preadv
#else
extern ssize_t pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset);
#endif

-#ifdef HAVE_PWRITEV
+#if HAVE_DECL_PWRITEV
#define pg_pwritev pwritev
#else
extern ssize_t pg_pwritev(int fd, const struct iovec *iov, int iovcnt, off_t offset);
diff --git a/src/tools/msvc/Solution.pm b/src/tools/msvc/Solution.pm
index 2f28de0355..7c235f227d 100644
--- a/src/tools/msvc/Solution.pm
+++ b/src/tools/msvc/Solution.pm
@@ -329,14 +329,14 @@ sub GenerateFiles
HAVE_PPC_LWARX_MUTEX_HINT => undef,
HAVE_PPOLL => undef,
HAVE_PREAD => undef,
- HAVE_PREADV => undef,
+ HAVE_DECL_PREADV => 0,
HAVE_PSTAT => undef,
HAVE_PS_STRINGS => undef,
HAVE_PTHREAD => undef,
HAVE_PTHREAD_IS_THREADED_NP => undef,
HAVE_PTHREAD_PRIO_INHERIT => undef,
HAVE_PWRITE => undef,
- HAVE_PWRITEV => undef,
+ HAVE_DECL_PWRITEV => 0,
HAVE_RANDOM => undef,
HAVE_READLINE_H => undef,
HAVE_READLINE_HISTORY_H => undef,
--
2.30.0