MbedTLS: Treat 0 bytes read/written to socket properly

At the moment, if a link quits in just the right (wrong [1]) way,
the quit reason will resemble:

    <-- foo (~bar@baz) has quit (Read error: (-0x0) )

This should resolve that.

[1] Peers should send a close_notify alert before abruptly shutting
    down their socket. This will result in a sane quit message:

    <-- foo (~bar@baz) has quit (Read error: (-0x7880) SSL -
    The peer notified us that the connection is going to be closed)

[ci skip]

diff --git a/librb/src/mbedtls.c b/librb/src/mbedtls.c
index 097fb811924ed0a97bc47f36e5b3bf23bcc74181..006ab20d36bb160a72655f992b6705ab612779dd 100644 (file)
--- a/librb/src/mbedtls.c
+++ b/librb/src/mbedtls.c
@@ -680,7 +680,7 @@ rb_ssl_read(rb_fde_t *const F, void *const buf, size_t count)
 
        ssize_t ret = (ssize_t) mbedtls_ssl_read(SSL_P(F), buf, count);
 
-       if(ret > 0)
+       if(ret >= 0)
                return ret;
 
        switch(ret)
@@ -706,7 +706,7 @@ rb_ssl_write(rb_fde_t *const F, const void *const buf, size_t count)
 
        ssize_t ret = (ssize_t) mbedtls_ssl_write(SSL_P(F), buf, count);
 
-       if(ret > 0)
+       if(ret >= 0)
                return ret;
 
        switch(ret)