Tightening behavior for unimplemented stream ops.

In many cases, if a stream operation is not applicable to a stream, it
is not appropriate to just do nothing and return nil. An error
must be thrown.

* stream.c (unimpl, unimpl_put_string, unimpl_put_char,
unimpl_put_byte, unimpl_get_line, unimpl_get_char, unimpl_get_byte,
unimpl_unget_char, unimpl_unget_byte, unimpl_seek, null_put_string,
null_put_char, null_put_byte, null_get_line, null_get_char,
null_get_byte, null_close, null_flush, null_seek, null_set_prop,
null_get_error, null_get_error_str, null_clear_error): New
static functions.
(fill_stream_ops): New function.
(null_ops): Use null_put_string, etc., instead of null pointers.
(stdio_clear_error, dir_clear_error, cat_clear_error): Return value now
indicating whether an error was cleared.
(stream_set_prop, stream_get_prop, real_time_stream_p, close_stream,
get_error, get_error_str, clear_error, get_line, get_char, get_byte,
unget_char, unget_byte, put_string, put_char, put_byte,
flush_stream): Do not test whether a function in the ops table
is defined; just call it, and return its value.
(stream_init): Call fill_stream_ops on all stream operation
structures so any null pointers are defaulted to appropriate
functions.

* stream.h (struct strm_ops): clear_error gets return value.
(fill_stream_ops): Declared.

* syslog.c (syslog_init): Call fill_stream_ops on syslog_strm_ops.

1 files changed, 4 insertions, 0 deletions

diff --git a/syslog.c b/syslog.c
index d4c5fb8a..cfc24cb8 100644
--- a/syslog.c
+++ b/syslog.c
@@ -45,6 +45,8 @@
 
 val prio_k;
 
+static struct strm_ops syslog_strm_ops;
+
 void syslog_init(void)
 {
   reg_var(intern(lit("log-pid"), user_package), num_fast(LOG_PID));
@@ -77,6 +79,8 @@ void syslog_init(void)
   prio_k = intern(lit("prio"), keyword_package);
 
   reg_var(intern(lit("*stdlog*"), user_package), make_syslog_stream(num_fast(LOG_INFO)));
+
+  fill_stream_ops(&syslog_strm_ops);
 }
 
 val openlog_wrap(val wident, val optmask, val facility)