crypto: Make unloading of crypto safer

Facts:
crypto nif-lib registers callback functions that openssl uses
for memory management and thread synchronization. The callback
functions can only be set once, openssl does not allow changing the
callback functions.

Problem:
If openssl is dynamicly linked to crypto, you might get s scenario
where the crypto lib is unloaded while leaving openssl loaded
with its old pointers to the unloaded crypto code intact.
If crypto is then reloaded (by init:restart() for example), the crypto
nif-lib might get relocated at a different address. crypto calls
openssl which in turn calls the old invalid callback functions...kaboom.

Solution:
Break apart the callback functions into a separate dynamic lib that
crypto loads with dlopen. When crypto is unloaded the callback lib is
left in place to be reused if/when crypto is loaded again.

2 files changed, 4 insertions, 4 deletions

diff --git a/erts/emulator/sys/unix/erl_unix_sys_ddll.c b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
index 336d9586c4..a35aec560a 100644
--- a/erts/emulator/sys/unix/erl_unix_sys_ddll.c
+++ b/erts/emulator/sys/unix/erl_unix_sys_ddll.c
@@ -101,7 +101,7 @@ void erl_sys_ddll_init(void) {
 /* 
  * Open a shared object
  */
-int erts_sys_ddll_open2(char *full_name, void **handle, ErtsSysDdllError* err)
+int erts_sys_ddll_open2(const char *full_name, void **handle, ErtsSysDdllError* err)
 {
 #if defined(HAVE_DLOPEN)
     char* dlname; 
@@ -153,7 +153,7 @@ int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
 /* 
  * Find a symbol in the shared object
  */
-int erts_sys_ddll_sym2(void *handle, char *func_name, void **function,
+int erts_sys_ddll_sym2(void *handle, const char *func_name, void **function,
 		       ErtsSysDdllError* err)
 {
 #if defined(HAVE_DLOPEN)
diff --git a/erts/emulator/sys/win32/erl_win32_sys_ddll.c b/erts/emulator/sys/win32/erl_win32_sys_ddll.c
index d00eed932b..54991a610c 100644
--- a/erts/emulator/sys/win32/erl_win32_sys_ddll.c
+++ b/erts/emulator/sys/win32/erl_win32_sys_ddll.c
@@ -58,7 +58,7 @@ void erl_sys_ddll_init(void) {
 /* 
  * Open a shared object
  */
-int erts_sys_ddll_open2(char *full_name, void **handle, ErtsSysDdllError* err)
+int erts_sys_ddll_open2(const char *full_name, void **handle, ErtsSysDdllError* err)
 {
     int len;
     char dlname[MAXPATHLEN + 1];
@@ -92,7 +92,7 @@ int erts_sys_ddll_open_noext(char *dlname, void **handle, ErtsSysDdllError* err)
 /* 
  * Find a symbol in the shared object
  */
-int erts_sys_ddll_sym2(void *handle, char *func_name, void **function,
+int erts_sys_ddll_sym2(void *handle, const char *func_name, void **function,
 		       ErtsSysDdllError* err)
 {
     FARPROC proc;