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1.17.5 SSL library initialization

If your application initializes libssl and/or libcrypto libraries and libpq is built with SSL support, you should call PQinitOpenSSL to tell libpq that the libssl and/or libcrypto libraries have been initialized by your application, so that libpq will not also initialize those libraries. See http://h71000.www7.hp.com/doc/83final/BA554_90007/ch04.html for details on the SSL API.

PQinitOpenSSL

Allows applications to select which security libraries to initialize.

void PQinitOpenSSL(int do_ssl, int do_crypto);

When do_ssl is non-zero, libpq will initialize the OpenSSL library before first opening a database connection. When do_crypto is non-zero, the libcrypto library will be initialized. By default (if PQinitOpenSSL is not called), both libraries are initialized. When SSL support is not compiled in, this function is present but does nothing. If your application uses and initializes either OpenSSL or its underlying libcrypto library, you must call this function with zeroes for the appropriate parameter(s) before first opening a database connection. Also be sure that you have done that initialization before opening a database connection.

PQinitSSL

Allows applications to select which security libraries to initialize.

void PQinitSSL(int do_ssl);

This function is equivalent to PQinitOpenSSL(do_ssl, do_ssl). It is sufficient for applications that initialize both or neither of OpenSSL and libcrypto. PQinitSSL has been present since PostgreSQL 8.0, while PQinitOpenSSL was added in PostgreSQL 8.4, so PQinitSSL might be preferable for applications that need to work with older versions of libpq.