Buffer size digit in file open mode string.

* streamn.c (struct stdio_handle): New member, buf.
(stdio_stream_destroy): Free the stdio_handle's buf.
(parse_mode): Handle digit character, converting it
to integer value stored in m.buforder.
(set_mode_props): Allocate a buffer and install into
FILE * stream if the mode specifies a buforder.
(make_stdio_stream_common): Initialize buffer to null.

* stream.h (struct stdio_mode): New signed bitfield
member, buforder.
(stdio_mode_init_trivial): Initialize buforder member
to -1.

* txr.1: Documented size order digit.

1 files changed, 13 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index 8c3ea260..6adb7dfa 100644
--- a/txr.1
+++ b/txr.1
@@ -34469,6 +34469,19 @@ mode letter specifies that the stream will be line buffered, unless
 specified as unbuffered with
 .strn u .
 
+In addition to option letters, decimal digit may be specified, influencing
+the stream buffer size. This digit specifies the buffer size as binary
+exponential buffer size order, such that
+.str 0
+specifies 1024 bytes,
+.str 1
+specifies 2048 and so forth up to
+.str 9
+specifying 524288 bytes. If no such digit is specified, then the
+stream uses a default buffer size. It is erroneous for the
+size order digit to be present together with the option
+.strn u .
+
 .coNP Function @ open-tail
 .synb
 .mets (open-tail < path >> [ mode-string <> [ seek-to-end-p ]])