Merge #15146: Solve SmartOS FD_ZERO build issue

b4fd0ca9be14c81023db759c405c0f67cfa78166 Include cstring for sanity_test_fdelt if required (Ben Woosley)
7fb886b1b1110de4c79478ac094e64cdcb81f3c8 [moveonly] Split glibc sanity_test_fdelt out (Ben Woosley)

Pull request description:

  SmartOS FD_ZERO is implemented in a way that requires
  an external declaration of memcpy. We can not simply
  include cstring in the existing file because
  sanity_test_memcpy is attempting to replace memcpy.

  Instead split glibc_sanity into fdelt and memcpy files,
  and include <cstring> in glibc_sanity/fdelt.cpp.

  Fixes #13581, see also #13619

ACKs for top commit:
  laanwj:
    Code review an lightly tested (but not on SmartOS) ACK b4fd0ca9be14c81023db759c405c0f67cfa78166

Tree-SHA512: 231306da291ad9eca8ba91bea1e9c27b6c2e96e484d1602e1c2cf27761202f9287ce0bc19fefd000943d2b449d0e5929cd39e2f7e09cf930d89fa520228ccbec

configure.ac

@@ -777,6 +777,39 @@ fi
 
 AC_CHECK_HEADERS([endian.h sys/endian.h byteswap.h stdio.h stdlib.h unistd.h strings.h sys/types.h sys/stat.h sys/select.h sys/prctl.h])
 
+# FD_ZERO may be dependent on a declaration of memcpy, e.g. in SmartOS
+# check that it fails to build without memcpy, then that it builds with
+AC_MSG_CHECKING(FD_ZERO memcpy dependence)
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+    #include <cstddef>
+    #if HAVE_SYS_SELECT_H
+    #include <sys/select.h>
+    #endif
+  ]],[[
+    #if HAVE_SYS_SELECT_H
+    fd_set fds;
+    FD_ZERO(&fds);
+    #endif
+  ]])],
+  [ AC_MSG_RESULT(no) ],
+  [
+      AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+          #include <cstring>
+          #if HAVE_SYS_SELECT_H
+          #include <sys/select.h>
+          #endif
+        ]], [[
+          #if HAVE_SYS_SELECT_H
+          fd_set fds;
+          FD_ZERO(&fds);
+          #endif
+        ]])],
+        [ AC_MSG_RESULT(yes); AC_DEFINE(HAVE_CSTRING_DEPENDENT_FD_ZERO, 1, [Define this symbol if FD_ZERO is dependent of a memcpy declaration being available]) ],
+        [ AC_MSG_ERROR(failed with cstring include) ]
+      )
+  ]
+)
+
 AC_CHECK_DECLS([getifaddrs, freeifaddrs],,,
     [#include <sys/types.h>
     #include <ifaddrs.h>]

src/Makefile.am

@@ -484,6 +484,7 @@ libbitcoin_util_a_SOURCES = \
   support/lockedpool.cpp \
   chainparamsbase.cpp \
   clientversion.cpp \
+  compat/glibc_sanity_fdelt.cpp \
   compat/glibc_sanity.cpp \
   compat/glibcxx_sanity.cpp \
   compat/strnlen.cpp \

src/compat/glibc_sanity.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2009-2018 The Bitcoin Core developers
+// Copyright (c) 2009-2019 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -9,7 +9,7 @@
 #include <cstddef>
 
 #if defined(HAVE_SYS_SELECT_H)
-#include <sys/select.h>
+bool sanity_test_fdelt();
 #endif
 
 extern "C" void* memcpy(void* a, const void* b, size_t c);
@@ -41,21 +41,6 @@ bool sanity_test_memcpy()
     }
     return true;
 }
-
-#if defined(HAVE_SYS_SELECT_H)
-// trigger: Call FD_SET to trigger __fdelt_chk. FORTIFY_SOURCE must be defined
-//   as >0 and optimizations must be set to at least -O2.
-// test: Add a file descriptor to an empty fd_set. Verify that it has been
-//   correctly added.
-bool sanity_test_fdelt()
-{
-    fd_set fds;
-    FD_ZERO(&fds);
-    FD_SET(0, &fds);
-    return FD_ISSET(0, &fds);
-}
-#endif
-
 } // namespace
 
 bool glibc_sanity_test()

src/compat/glibc_sanity_fdelt.cpp

@@ -0,0 +1,26 @@
+// Copyright (c) 2009-2019 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#if defined(HAVE_SYS_SELECT_H)
+#ifdef HAVE_CSTRING_DEPENDENT_FD_ZERO
+#include <cstring>
+#endif
+#include <sys/select.h>
+
+// trigger: Call FD_SET to trigger __fdelt_chk. FORTIFY_SOURCE must be defined
+//   as >0 and optimizations must be set to at least -O2.
+// test: Add a file descriptor to an empty fd_set. Verify that it has been
+//   correctly added.
+bool sanity_test_fdelt()
+{
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(0, &fds);
+    return FD_ISSET(0, &fds);
+}
+#endif