libpq: Don't overwrite existing OpenSSL thread callbacks

If someone else already set the callbacks, don't overwrite them with
ours.  When unsetting the callbacks, only unset them if they point to
ours.

Author: Jan Urbański 

diff --git a/src/interfaces/libpq/fe-secure-openssl.c b/src/interfaces/libpq/fe-secure-openssl.c
index 1b9f3a4a7b0a7ad065c62bfcd1a85ba3c3b91df1..fee154904a61e4f9068b2f18a92482d4f774f05d 100644 (file)
--- a/src/interfaces/libpq/fe-secure-openssl.c
+++ b/src/interfaces/libpq/fe-secure-openssl.c
@@ -806,9 +806,12 @@ pgtls_init(PGconn *conn)
 
        if (ssl_open_connections++ == 0)
        {
-           /* These are only required for threaded libcrypto applications */
-           CRYPTO_set_id_callback(pq_threadidcallback);
-           CRYPTO_set_locking_callback(pq_lockingcallback);
+           /* These are only required for threaded libcrypto applications, but
+            * make sure we don't stomp on them if they're already set. */
+           if (CRYPTO_get_id_callback() == NULL)
+               CRYPTO_set_id_callback(pq_threadidcallback);
+           if (CRYPTO_get_locking_callback() == NULL)
+               CRYPTO_set_locking_callback(pq_lockingcallback);
        }
    }
 #endif   /* ENABLE_THREAD_SAFETY */
@@ -885,9 +888,12 @@ destroy_ssl_system(void)
 
    if (pq_init_crypto_lib && ssl_open_connections == 0)
    {
-       /* No connections left, unregister libcrypto callbacks */
-       CRYPTO_set_locking_callback(NULL);
-       CRYPTO_set_id_callback(NULL);
+       /* No connections left, unregister libcrypto callbacks, if no one
+        * registered different ones in the meantime. */
+       if (CRYPTO_get_locking_callback() == pq_lockingcallback)
+           CRYPTO_set_locking_callback(NULL);
+       if (CRYPTO_get_id_callback() == pq_threadidcallback)
+           CRYPTO_set_id_callback(NULL);
 
        /*
         * We don't free the lock array or the SSL_context. If we get another