Detect PTYs that aren't sufficiently functional to be considered as smart

In this case, the offender is the PTY that is set up by the
_create_pty_or_pipe() utility function in portage, which uses python's
pty module. I transpires that its behaviour is not exactly equivalent to
whichever controlling terminal is in effect at the time that emerge(1)
is executed, if any. As a consequence, the ecma48-cpr utility times out
while waiting for a response to the CPR (ECMA-48 CSI) sequence.

I can discern no option other than to refrain from considering the
terminal as being "smart" in this case. This is accomplished by
recognising that stty(1) reports "0 0" when asked to check its size.
These are nonsensical readings that would never be produced for a
properly functioning, non-dumb terminal. In fact, this check used to be
in place but was removed, simply because I forgot how important it is.

Processes running under portage that call into gentoo-functions will
still be able to produce coloured messages, but all the advantages of
the smart terminal handling path will be obviated. This is unfortunate,
but I have no intention of returning to the original, broken behaviour
of gentoo-functions, which was to assume that the characteristics of the
terminal found at the time of sourcing hold forever, and that STDOUT
and STDERR will never refer to anything other than that same terminal.

I would add that script(1) does not exhibit the same issue.

$ tty
/dev/pts/0
$ script -c 'tty; stty size <&1; /lib/gentoo/ecma48-cpr <&1' /dev/null
Script started, output log file is '/dev/null'.
/dev/pts/11
34 144
34 1
Script done.

In other words, it is portage that is broken and which should be fixed.

Signed-off-by: Kerin Millar <kfm@plushkava.net>
Reported-by: Sam James <sam@gentoo.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/functions.sh.in b/functions.sh.in
index 9be9978..6f1ee75 100644
--- a/functions.sh.in
+++ b/functions.sh.in
@@ -626,7 +626,7 @@ _update_winsize() {
 	# it may eventually become possible to support it.
 	# shellcheck disable=2046
 	set -- $(stty size 2>/dev/null)
-	if [ "$#" -eq 2 ] && is_int "$1" && is_int "$2"; then
+	if [ "$#" -eq 2 ] && is_int "$1" && is_int "$2" && [ "$1" -gt 0 ] && [ "$2" -gt 0 ]; then
 		genfun_rows=$1
 		genfun_cols=$2
 	else