Clarify clear-error and flush return value.

* stream.c (stdio_clear_error): Return the prior value of h->err.
Do not inspect feof(h->f) or ferror(h->f); just clear the error
status of the stream.
(stdio_close): Set h->err from errno if fclose failed.
(dir_clear_error): Return prior value of h->err.

* txr.1: Document return value convetion for clear-error,
and flush-stream.

1 files changed, 5 insertions, 1 deletions

diff --git a/txr.1 b/txr.1
index 0afc90c3..2eeea9c6 100644
--- a/txr.1
+++ b/txr.1
@@ -24228,6 +24228,9 @@ The
 function removes the error situation from a stream. On some streams, it does
 nothing. If an error has occurred on a stream, this function should be called
 prior to re-trying any I/O or positioning operations.
+The return value is the previous error code, or
+.code nil
+if there was no error, or the operation is not supported on the stream.
 
 .coNP Functions @, get-line @ get-char and @ get-byte
 .synb
@@ -24452,7 +24455,8 @@ causes all accumulated data inside
 .meta stream
 to be passed
 to the operating system. If called on streams for which this function is not
-meaningful, it does nothing.
+meaningful, it does nothing, and returns
+.codn nil .
 
 .coNP Function @ seek-stream
 .synb