workaround for a bug in sysread

There is a bug in sysread from zsh/system. It triggers in the
following case:

1. zsh has been compiled with HAVE_SELECT and without HAVE_POLL.
2. sysread is called with timeout (-t).
3. the input file descriptor is valid but there is no data to read.
4. errno happens to be EINTR prior to the call to sysread.

This results in an infinite loop in sysread:

  while ((ret = select(infd+1, (SELECT_ARG_2_T) &fds,
                       NULL, NULL,&select_tv)) < 1) {
    if (errno != EINTR || errflag || retflag || breaks || contflag)
      break;
  }

Here select() keeps returning 0, indicating timeout. This is not an
error, so errno doesn't get set. If it was EINTR prior to the call,
it stays EINTR, and the loop keeps spinning.

As a workaround, powerlevel10k sets errno to ENOTTY (any value other
than EINTR will do) prior to calling sysread with timeout.
pull/471/head
romkatv 5 years ago
parent a12f7ac8ee
commit 7354eeaa96

@ -4154,22 +4154,27 @@ function _p9k_fetch_nordvpn_status() {
>&$fd echo -nE - $'PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n\0\0\0\4\1\0\0\0\0\0\0N\1\4\0\0\0\1\203\206E\221bA\226\223\325\\k\337\31i=LnH\323j?A\223\266\243y\270\303\fYmLT{$\357]R.\203\223\257_\213\35u\320b\r&=LMedz\212\232\312\310\264\307`+\210K\203@\2te\206M\2035\5\261\37\0\0\5\0\1\0\0\0\1\0\0\0\0\0' >&$fd echo -nE - $'PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n\0\0\0\4\1\0\0\0\0\0\0N\1\4\0\0\0\1\203\206E\221bA\226\223\325\\k\337\31i=LnH\323j?A\223\266\243y\270\303\fYmLT{$\357]R.\203\223\257_\213\35u\320b\r&=LMedz\212\232\312\310\264\307`+\210K\203@\2te\206M\2035\5\261\37\0\0\5\0\1\0\0\0\1\0\0\0\0\0'
local tag len val local tag len val
local -i n local -i n
IFS='' read -t 0.25 -r tag <&3 {
tag=$'\015' IFS='' read -t 0.25 -r tag
while true; do tag=$'\015'
tag=$((#tag)) while true; do
(( (tag >>= 3) && tag <= $#__p9k_nordvpn_tag )) || break tag=$((#tag))
tag=$__p9k_nordvpn_tag[tag] (( (tag >>= 3) && tag <= $#__p9k_nordvpn_tag )) || break
sysread -c n -s 1 -t 0.25 len <&3 tag=$__p9k_nordvpn_tag[tag]
len=$((#len)) [[ -t $fd ]] || true
val= sysread -c n -s 1 -t 0.25 len
(( ! len )) || { len=$((#len))
sysread -c n -s $len -t 0.25 val <&3 val=
(( n == len )) (( ! len )) || {
} [[ -t $fd ]] || true
typeset -g $tag=$val sysread -c n -s $len -t 0.25 val
sysread -c n -s 1 -t 0.25 tag <&3 (( n == len ))
done }
typeset -g $tag=$val
[[ -t $fd ]] || true
sysread -c n -s 1 -t 0.25 tag
done
} <&$fd
} always { } always {
exec {fd}>&- exec {fd}>&-
} }

@ -34,6 +34,7 @@ function _p9k_worker_main() {
if [[ $fd == 0 ]]; then if [[ $fd == 0 ]]; then
local buf= local buf=
while true; do while true; do
[[ -t 0 ]]
sysread -t 0 'buf[$#buf+1]' && continue sysread -t 0 'buf[$#buf+1]' && continue
(( $? == 4 )) || return (( $? == 4 )) || return
[[ $buf[-1] == (|$'\x1e') ]] && break [[ $buf[-1] == (|$'\x1e') ]] && break
@ -115,6 +116,7 @@ function _p9k_worker_receive() {
local buf resp local buf resp
while true; do while true; do
[[ -t $_p9k__worker_resp_fd ]]
sysread -t 0 -i $_p9k__worker_resp_fd 'buf[$#buf+1]' && continue sysread -t 0 -i $_p9k__worker_resp_fd 'buf[$#buf+1]' && continue
(( $? == 4 )) || return (( $? == 4 )) || return
[[ $buf == (|*$'\x1e')$'\x05'# ]] && break [[ $buf == (|*$'\x1e')$'\x05'# ]] && break

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