Xen devel - Feb 2013 - [PATCH] tools/xc: update tty detection in stdiostream_progress

# HG changeset patch
# User Olaf Hering <olaf@aepfle.de>
# Date 1361561865 -3600
# Node ID 1b36a6c0a956cc94ddb0024099bf60fb4cbe02d7
# Parent  dc086ced6b0c7ecf21e56155f42fb16dabe39097
tools/xc: update tty detection in stdiostream_progress

As suggested by IanJ:
Check isatty only once to preserve the errno of ->progress users, and to
reduce the noice in strace output.

Signed-off-by: Olaf Hering <olaf@aepfle.de>

diff -r dc086ced6b0c -r 1b36a6c0a956 tools/libxc/xtl_logger_stdio.c
--- a/tools/libxc/xtl_logger_stdio.c
+++ b/tools/libxc/xtl_logger_stdio.c
@@ -35,6 +35,7 @@ struct xentoollog_logger_stdiostream {
     xentoollog_level min_level;
     unsigned flags;
     int progress_erase_len, progress_last_percent;
+    int isatty;
 };
 
 static void progress_erase(xentoollog_logger_stdiostream *lg) {
@@ -118,7 +119,7 @@ static void stdiostream_progress(struct 
 
     lg->progress_last_percent = percent;
 
-    if (isatty(fileno(lg->f)) <= 0) {
+    if (!lg->isatty) {
         stdiostream_message(logger_in, this_level, context,
                             "%s: %lu/%lu  %3d%%",
                             doing_what, done, total, percent);
@@ -166,6 +167,7 @@ xentoollog_logger_stdiostream *xtl_creat
     newlogger.f = f;
     newlogger.min_level = min_level;
     newlogger.flags = flags;
+    newlogger.isatty = isatty(fileno(lg->f)) > 0;
 
     if (newlogger.flags & XTL_STDIOSTREAM_SHOW_DATE) tzset();

Olaf Hering writes ("[Xen-devel] [PATCH] tools/xc: update tty detection in
stdiostream_progress"):
> tools/xc: update tty detection in stdiostream_progress
> 
> As suggested by IanJ:
> Check isatty only once to preserve the errno of ->progress users, and to
> reduce the noice in strace output.
> 
> Signed-off-by: Olaf Hering <olaf@aepfle.de>
Thanks.  But how did you test this ?  It doesn''t compile.

Also I think it would be better to name the struct member something
other than "isatty" since that''s also the function name.  In
theory it
should be OK but in practice I worry about compiler warnings etc.

How about "tty" ?

Ian.

On Tue, Feb 26, Ian Jackson wrote:
> Olaf Hering writes ("[Xen-devel] [PATCH] tools/xc: update tty
detection in stdiostream_progress"):
> > tools/xc: update tty detection in stdiostream_progress
> > 
> > As suggested by IanJ:
> > Check isatty only once to preserve the errno of ->progress users,
and to
> > reduce the noice in strace output.
> > 
> > Signed-off-by: Olaf Hering <olaf@aepfle.de>
> 
> Thanks.  But how did you test this ?  It doesn''t compile.
I noticed that compiler error but forgot to do qrefresh before sending.
> Also I think it would be better to name the struct member something
> other than "isatty" since that''s also the function name.
In theory it
> should be OK but in practice I worry about compiler warnings etc.
> 
> How about "tty" ?
Will rename the member to tty and resend.

Olaf