only use posix_fallocate() if it's actually available

bridges/source/cpp_uno/shared/makefile.mk

@@ -33,6 +33,10 @@ ENABLE_EXCEPTIONS = TRUE
 
 .INCLUDE: settings.mk
 
+.IF "$(HAVE_POSIX_FALLOCATE)" == "YES"
+CDEFS += -DHAVE_POSIX_FALLOCATE
+.ENDIF
+
 SLOFILES = \
     $(SLO)$/bridge.obj \
     $(SLO)$/component.obj \

bridges/source/cpp_uno/shared/vtablefactory.cxx

@@ -264,10 +264,18 @@ bool VtableFactory::createBlock(Block &block, sal_Int32 slotCount) const
         }
         unlink(tmpfname);
         delete[] tmpfname;
+#if defined(HAVE_POSIX_FALLOCATE)
         int err = posix_fallocate(block.fd, 0, block.size);
+#else
+        int err = ftruncate(block.fd, block.size);
+#endif
         if (err != 0)
         {
+#if defined(HAVE_POSIX_FALLOCATE)
             SAL_WARN("bridges", "posix_fallocate failed with code " << err);
+#else
+            SAL_WARN("bridges", "truncation of executable memory area failed with code " << err);
+#endif
             close(block.fd);
             block.fd = -1;
             break;

configure.in

@@ -3879,6 +3879,8 @@ fi
 if test "$with_alloc" = "internal" -o -z "$with_alloc"; then
     AC_MSG_RESULT([internal])
 fi
+AC_CHECK_FUNCS(posix_fallocate, HAVE_POSIX_FALLOCATE=YES, [HAVE_POSIX_FALLOCATE=NO])
+AC_SUBST(HAVE_POSIX_FALLOCATE)
 AC_SUBST(ALLOC)
 
 dnl ===================================================================

set_soenv.in

@@ -1934,6 +1934,7 @@ ToFile( "HUNSPELL_LIBS",     "@HUNSPELL_LIBS@",    "e" );
 ToFile( "SYSTEM_LPSOLVE",    "@SYSTEM_LPSOLVE@",   "e" );
 ToFile( "HAVE_GETOPT",       "@HAVE_GETOPT@",      "e" );
 ToFile( "HAVE_READDIR_R",    "@HAVE_READDIR_R@",   "e" );
+ToFile( "HAVE_POSIX_FALLOCATE",    "@HAVE_POSIX_FALLOCATE@",   "e" );
 ToFile( "SYSTEM_LIBC",       "@SYSTEM_LIBC@",      "e" );
 ToFile( "SYSTEM_HYPH",       "@SYSTEM_HYPH@",      "e" );
 ToFile( "HYPHEN_LIB",        "@HYPHEN_LIB@",       "e" );