Update documentation for PEM callback: error is now -1.

In previous versions of OpenSSL, the documentation for PEM_read_*
said:

   The callback B<must> return the number of characters in the
   passphrase or 0 if an error occurred.

But since c82c3462267afdbbaa5, 0 is now treated as a non-error
return value.  Applications that want to indicate an error need to
return -1 instead.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6271)

(cherry picked from commit bbbf752a3c8b5a966bcb48fc71a3dc03832e7b27)
(cherry picked from commit e4b47f7f19392e3be604e44f6999de2bc9e7ecf3)

diff --git a/doc/crypto/pem.pod b/doc/crypto/pem.pod
index 763eb6f533925e71580ea2568b27cc9f7107aa55..d54a09c5d1be1f926f2ca6e80332608bf3a8df19 100644 (file)
--- a/doc/crypto/pem.pod
+++ b/doc/crypto/pem.pod
@@ -342,7 +342,7 @@ for it twice) if B<rwflag> is 1. The B<u> parameter has the same
 value as the B<u> parameter passed to the PEM routine. It allows
 arbitrary data to be passed to the callback by the application
 (for example a window handle in a GUI application). The callback
-B<must> return the number of characters in the passphrase or 0 if
+B<must> return the number of characters in the passphrase or -1 if
 an error occurred.
 
 =head1 EXAMPLES