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|
# Helper function for reading input from a TCP connection.
# Actually, the input doesn't need to be a TCP connection at all, it
# is simply an input file descriptor. However, it must be contained
# in ${tcp_by_fd[$TCP_SESS]}. This is set set by tcp_open, but may be
# set by hand. (Note, however, the blocking/timeout behaviour is usually
# not implemented for reading from regular files.)
#
# The default behaviour is simply to read any single available line from
# the input fd and print it. If a line is read, it is stored in the
# parameter $TCP_LINE; this always contains the last line successfully
# read. Any chunk of lines read in are stored in the array $tcp_lines;
# this always contains a complete list of all lines read in by a single
# execution of this function and hence may be empty. The fd corresponding
# to $TCP_LINE is stored in $TCP_LINE_FD (this can be turned into a
# session by looking up in $tcp_by_fd).
#
# Printed lines are preceded by $TCP_PROMPT. This may contain two
# percent escapes: %s for the current session, %f for the current file
# descriptor. The default is `T[%s]:'. The prompt is not printed
# to per-session logs where the source is unambiguous.
#
# The function returns 0 if a read succeeded, even if (using -d) a
# subsequent read failed.
#
# The behaviour is modified by the following options.
#
# -a Read from all fds, not just the one given by TCP_SESS.
#
# -b The first read blocks until some data is available for reading.
#
# -d Drain all pending input; loop until no data is available.
#
# -l sess1,sess2,...
# Gives a list of sessions to read on. Equivalent to
# -u ${tcp_by_name[sess1]} -u ${tcp_by_name[sess2]} ...
# Multiple -l options also work.
#
# -q Quiet; if $TCP_SESS is not set, just return 1, but don't print
# an error message.
#
# -s sess
# Gives a single session; the option may be repeated.
#
# -t TO On each read (the only read unless -d was also given), time out
# if nothing was available after TO seconds (may be floating point).
# Otherwise, the function will return immediately when no data is
# available.
#
# If combined with -b, the function will always wait for the
# first data to become available; hence this is not useful unless
# -d is specified along with -b, in which case the timeout applies
# to data after the first line.
# -u fd Read from fd instead of the default session; may be repeated for
# multiple sessions. Can be a comma-separated list, too.
# -T TO This sets an overall timeout, again in seconds.
emulate -L zsh
setopt extendedglob cbases
# set -x
zmodload -i zsh/mathfunc
local opt drain line quiet block read_fd all sess
local -A read_fds
read_fds=()
float timeout timeout_all endtime
integer stat
while getopts "abdl:qs:t:T:u:" opt; do
case $opt in
# Read all sessions.
(a) all=1
;;
# Block until we receive something.
(b) block=1
;;
# Drain all pending input.
(d) drain=1
;;
(l) for sess in ${(s.,.)OPTARG}; do
read_fd=${tcp_by_name[$sess]}
if [[ -z $read_fd ]]; then
print "$0: no such session: $sess" >&2
return 1
fi
read_fds[$read_fd]=1
done
;;
# Don't print an error mesage if there is no TCP connection,
# just return 1.
(q) quiet=1
;;
# Add a single session to the list
(s) read_fd=${tcp_by_name[$OPTARG]}
if [[ -z $read_fd ]]; then
print "$0: no such session: $sess" >&2
return 1
fi
read_fds[$read_fd]=1
;;
# Per-read timeout: wait this many seconds before
# each read.
(t) timeout=$OPTARG
[[ -n $TCP_READ_DEBUG ]] && print "Timeout per-operations is $timeout" >&2
;;
# Overall timeout: return after this many seconds.
(T) timeout_all=$OPTARG
;;
# Read from given fd(s).
(u) for read_fd in ${(s.,.)OPTARG}; do
if [[ $read_fd != (0x[[:xdigit:]]##|[[:digit:]]##) ]]; then
print "Bad fd in $OPTARG" >&2
return 1
fi
read_fds[$((read_fd))]=1
done
;;
(*) [[ $opt != \? ]] && print Unhandled option, complain: $opt >&2
return 1
;;
esac
done
if [[ -n $all ]]; then
read_fds=(${(kv)tcp_by_fd})
elif (( ! $#read_fds )); then
if [[ -z $TCP_SESS ]]; then
[[ -z $quiet ]] && print "No tcp connection open." >&2
return 1
elif [[ -z $tcp_by_name[$TCP_SESS] ]]; then
print "TCP session $TCP_SESS has gorn!" >&2
return 1
fi
read_fds[$tcp_by_name[$TCP_SESS]]=1
fi
tcp_lines=()
local helper_stat=2 skip tpat reply REPLY
float newtimeout
# Get extra accuracy by making SECONDS floating point locally
typeset -F SECONDS
if (( timeout_all )); then
(( endtime = SECONDS + timeout_all ))
fi
zmodload -i zsh/zselect
if [[ -n $block ]]; then
if (( timeout_all )); then
# zselect -t uses 100ths of a second
zselect -t $(( int(100*timeout_all + 0.5) )) ${(k)read_fds} ||
return $helper_stat
else
zselect ${(k)read_fds} || return $helper_stat
fi
fi
while (( ${#read_fds} )); do
if [[ -n $block ]]; then
# We already have data waiting this time through.
unset block
else
if (( timeout_all )); then
(( (newtimeout = endtime - SECONDS) <= 0 )) && return 2
if (( ! timeout || newtimeout < timeout )); then
(( timeout = newtimeout ))
fi
fi
if (( timeout )); then
if [[ -n $TCP_READ_DEBUG ]]; then
print "[tcp_read: selecting timeout $timeout on ${(k)read_fds}]" >&2
fi
zselect -t $(( int(timeout*100 + 0.5) )) ${(k)read_fds} ||
return $helper_stat
else
if [[ -n $TCP_READ_DEBUG ]]; then
print "[tcp_read: selecting no timeout on ${(k)read_fds}]" >&2
fi
zselect -t 0 ${(k)read_fds} || return $helper_stat
fi
fi
if [[ -n $TCP_READ_DEBUG ]]; then
print "[tcp_read: returned fds ${reply}]" >&2
fi
for read_fd in ${reply[2,-1]}; do
if ! read -r line <&$read_fd; then
unset "read_fds[$read_fd]"
stat=1
continue
fi
helper_stat=0
sess=${tcp_by_fd[$read_fd]}
tcp_output -P "${TCP_PROMPT:=<-[%s] }" -S $sess -F $read_fd \
${TCP_SILENT:+-q} "$line"
# REPLY is now set to the line with an appropriate prompt.
tcp_lines+=($REPLY)
TCP_LINE=$REPLY TCP_LINE_FD=$read_fd
# Only handle one line from one device at a time unless draining.
[[ -z $drain ]] && return $stat
done
done
return $stat
|
