Link using -znodelete

Instead of deliberately leaking a reference to ourselves, use nodelete
which does this more neatly. Only for Linux at the moment.
Reviewed-by: NTim Hudson <tjh@openssl.org>

Configurations/10-main.conf

@@ -632,7 +632,8 @@ sub vms_info {
         thread_scheme    => "pthreads",
         dso_scheme       => "dlfcn",
         shared_target    => "linux-shared",
-        shared_cflag     => "-fPIC",
+        shared_cflag     => "-fPIC -DOPENSSL_USE_NODELETE",
+        shared_ldflag    => "-znodelete",
         shared_extension => ".so.\$(SHLIB_MAJOR).\$(SHLIB_MINOR)",
     },
     "linux-generic64" => {
@@ -648,14 +649,14 @@ sub vms_info {
         inherit_from     => [ "linux-generic64", asm("ppc64_asm") ],
         cflags           => add("-m64 -DB_ENDIAN"),
         perlasm_scheme   => "linux64",
-        shared_ldflag    => "-m64",
+        shared_ldflag    => add("-m64"),
         multilib         => "64",
     },
     "linux-ppc64le" => {
         inherit_from     => [ "linux-generic64", asm("ppc64_asm") ],
         cflags           => add("-m64 -DL_ENDIAN"),
         perlasm_scheme   => "linux64le",
-        shared_ldflag    => "-m64",
+        shared_ldflag    => add("-m64"),
     },
 
     "linux-armv4" => {
@@ -711,7 +712,7 @@ sub vms_info {
         inherit_from     => [ "linux-generic32", asm("mips32_asm") ],
         cflags           => add("-mabi=32 -DBN_DIV3W"),
         perlasm_scheme   => "o32",
-        shared_ldflag    => "-mabi=32",
+        shared_ldflag    => add("-mabi=32"),
     },
     # mips32 and mips64 below refer to contemporary MIPS Architecture
     # specifications, MIPS32 and MIPS64, rather than to kernel bitness.
@@ -720,14 +721,14 @@ sub vms_info {
         cflags           => add("-mabi=n32 -DBN_DIV3W"),
         bn_ops           => "SIXTY_FOUR_BIT RC4_CHAR",
         perlasm_scheme   => "n32",
-        shared_ldflag    => "-mabi=n32",
+        shared_ldflag    => add("-mabi=n32"),
         multilib         => "32",
     },
     "linux64-mips64" => {
         inherit_from     => [ "linux-generic64", asm("mips64_asm") ],
         cflags           => add("-mabi=64 -DBN_DIV3W"),
         perlasm_scheme   => "64",
-        shared_ldflag    => "-mabi=64",
+        shared_ldflag    => add("-mabi=64"),
         multilib         => "64",
     },
 
@@ -754,7 +755,7 @@ sub vms_info {
         cflags           => add("-m64 -DL_ENDIAN"),
         bn_ops           => "SIXTY_FOUR_BIT_LONG",
         perlasm_scheme   => "elf",
-        shared_ldflag    => "-m64",
+        shared_ldflag    => add("-m64"),
         multilib         => "64",
     },
     "linux-x86_64-clang" => {
@@ -781,7 +782,7 @@ sub vms_info {
         inherit_from     => [ "linux-generic64", asm("s390x_asm") ],
         cflags           => add("-m64 -DB_ENDIAN"),
         perlasm_scheme   => "64",
-        shared_ldflag    => "-m64",
+        shared_ldflag    => add("-m64"),
         multilib         => "64",
     },
     "linux32-s390x" => {
@@ -805,7 +806,7 @@ sub vms_info {
         cflags           => add("-m31 -Wa,-mzarch -DB_ENDIAN"),
         bn_asm_src       => sub { my $r=join(" ",@_); $r=~s|asm/s390x\.S|bn_asm.c|; $r; },
         perlasm_scheme   => "31",
-        shared_ldflag    => "-m31",
+        shared_ldflag    => add("-m31"),
         multilib         => "/highgprs",
     },
 
@@ -821,14 +822,14 @@ sub vms_info {
         # but -Wa,-Av8plus should do the trick no matter what.
         inherit_from     => [ "linux-generic32", asm("sparcv9_asm") ],
         cflags           => add("-m32 -mcpu=ultrasparc -Wa,-Av8plus -DB_ENDIAN -DBN_DIV2W"),
-        shared_ldflag    => "-m32",
+        shared_ldflag    => add("-m32"),
     },
     "linux64-sparcv9" => {
         # GCC 3.1 is a requirement
         inherit_from     => [ "linux-generic64", asm("sparcv9_asm") ],
         cflags           => add("-m64 -mcpu=ultrasparc -DB_ENDIAN"),
         bn_ops           => "BN_LLONG RC4_CHAR",
-        shared_ldflag    => "-m64",
+        shared_ldflag    => add("-m64"),
         multilib         => "64",
     },
 
@@ -857,7 +858,7 @@ sub vms_info {
         dso_scheme       => "dlfcn",
         shared_target    => "linux-shared",
         shared_cflag     => "--pic",
-        shared_ldflag    => "-z --sysv --shared",
+        shared_ldflag    => add("-z --sysv --shared"),
         shared_extension => ".so.\$(SHLIB_MAJOR).\$(SHLIB_MINOR)",
         ranlib           => "true",
     },

crypto/init.c

@@ -81,6 +81,7 @@ DEFINE_RUN_ONCE_STATIC(ossl_init_base)
     OPENSSL_cpuid_setup();
     base_inited = 1;
 
+#ifndef OPENSSL_USE_NODELETE
     /*
      * Deliberately leak a reference to ourselves. This will force the library
      * to remain loaded until the atexit() handler is run a process exit.
@@ -91,6 +92,7 @@ DEFINE_RUN_ONCE_STATIC(ossl_init_base)
         dso = DSO_dsobyaddr(&base_inited, DSO_FLAG_NO_UNLOAD_ON_FREE);
         DSO_free(dso);
     }
+#endif
 
     return 1;
 }
@@ -588,10 +590,11 @@ int OPENSSL_atexit(void (*handler)(void))
 {
     OPENSSL_INIT_STOP *newhand;
 
+#ifndef OPENSSL_USE_NODELETE
     /*
      * Deliberately leak a reference to the handler. This will force the
      * library/code containing the handler to remain loaded until we run the
-     * atexit handler.
+     * atexit handler. If -znodelete has been used then this is unneccessary.
      */
     {
         DSO *dso = NULL;
@@ -605,6 +608,7 @@ int OPENSSL_atexit(void (*handler)(void))
         dso = DSO_dsobyaddr(handlersym.sym, DSO_FLAG_NO_UNLOAD_ON_FREE);
         DSO_free(dso);
     }
+#endif
 
     newhand = OPENSSL_malloc(sizeof(*newhand));
     if (newhand == NULL)