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#!/bin/sh
# update feeds, merge with old feeds.
# NOTE: assumes "sfeed_*" executables are in $PATH.
# defaults
sfeedpath="$HOME/.sfeed/feeds"
# used for processing feeds concurrently: wait until ${maxjobs} amount of
# feeds are finished at a time.
maxjobs=8
# load config (evaluate shellscript).
# loadconfig(configfile)
loadconfig() {
# allow to specify config via argv[1].
if [ "$1" != "" ]; then
# get absolute path of config file.
config=$(readlink -f "$1")
else
# default config location.
config="$HOME/.sfeed/sfeedrc"
fi
# config is loaded here to be able to override $sfeedpath or functions.
if [ -r "${config}" ]; then
. "${config}"
else
echo "Configuration file \"${config}\" does not exist or is not readable." >&2
echo "See sfeedrc.example for an example." >&2
exit 1
fi
}
# log(name,s)
log() {
printf '[%s] %-50.50s %s\n' "$(date +'%H:%M:%S')" "$1" "$2" >&2
}
# fetch a feed via HTTP/HTTPS etc.
# fetch(name, url, feedfile)
fetch() {
# fail on redirects, hide User-Agent, timeout is 15 seconds,
# -z for If-Modified-Since.
curl -L --max-redirs 0 -H "User-Agent:" -f -s -m 15 \
-z "$3" "$2" 2>/dev/null
}
# convert encoding from one encoding to another.
# convertencoding(from, to)
convertencoding() {
if [ "$1" != "" ] && [ "$2" != "" ] && [ "$1" != "$2" ]; then
iconv -cs -f "$1" -t "$2" 2> /dev/null
else
# else no convert, just output
cat
fi
}
# filter fields.
# filter(name)
filter() {
cat
}
# order by timestamp (descending).
# order(name)
order() {
sort -t ' ' -k1rn,1
}
# merge raw files: unique sort by id, title, link.
# merge(name, oldfile, newfile)
merge() {
sort -t ' ' -u -k6,6 -k2,2 -k3,3 "$2" "$3" 2>/dev/null
}
# fetch and parse feed.
# feed(name, feedurl, [basesiteurl], [encoding])
feed() {
# wait until ${maxjobs} are finished: throughput using this logic is
# non-optimal, but it is simple and portable.
[ ${signo} -ne 0 ] && return
[ $((curjobs % maxjobs)) -eq 0 ] && wait
[ ${signo} -ne 0 ] && return
curjobs=$((curjobs + 1))
(name="$1"
filename="$(printf '%s' "$1" | tr '/' '_')"
feedurl="$2"
basesiteurl="$3"
encoding="$4"
sfeedfile="${sfeedpath}/${filename}"
tmpfeedfile="${sfeedtmpdir}/${filename}"
if ! fetch "${name}" "${feedurl}" "${sfeedfile}" > "${tmpfeedfile}.fetch"; then
log "${name}" "FAIL (FETCH)"
return
fi
# try to detect encoding (if not specified). if detecting the encoding fails assume utf-8.
[ "${encoding}" = "" ] && encoding=$(sfeed_xmlenc < "${tmpfeedfile}.fetch")
if ! convertencoding "${encoding}" "utf-8" < "${tmpfeedfile}.fetch" > "${tmpfeedfile}.utf8"; then
log "${name}" "FAIL (ENCODING)"
return
fi
rm -f "${tmpfeedfile}.fetch"
if ! sfeed "${basesiteurl}" < "${tmpfeedfile}.utf8" > "${tmpfeedfile}.tsv"; then
log "${name}" "FAIL (CONVERT)"
return
fi
rm -f "${tmpfeedfile}.enc"
if ! filter "${name}" < "${tmpfeedfile}.tsv" > "${tmpfeedfile}.filter"; then
log "${name}" "FAIL (FILTER)"
return
fi
rm -f "${tmpfeedfile}.tsv"
# new feed data is empty: no need for below stages.
if [ ! -s "${tmpfeedfile}.filter" ]; then
log "${name}" "OK"
return
fi
# if file does not exist yet "merge" with /dev/null.
if [ -e "${sfeedfile}" ]; then
oldfile="${sfeedfile}"
else
oldfile="/dev/null"
fi
if ! merge "${name}" "${oldfile}" "${tmpfeedfile}.filter" > "${tmpfeedfile}.merge"; then
log "${name}" "FAIL (MERGE)"
return
fi
rm -f "${tmpfeedfile}.filter"
if ! order "${name}" < "${tmpfeedfile}.merge" > "${tmpfeedfile}.order"; then
log "${name}" "FAIL (ORDER)"
return
fi
rm -f "${tmpfeedfile}.merge"
# atomic move.
if ! mv "${tmpfeedfile}.order" "${sfeedfile}"; then
log "${name}" "FAIL (MOVE)"
return
fi
# OK
log "${name}" "OK"
) &
}
cleanup() {
# remove temporary directory with feed files.
rm -rf "${sfeedtmpdir}"
}
sighandler() {
signo="$1"
# ignore TERM signal for myself.
trap -- "" TERM
# kill all running childs >:D
kill -TERM -$$
}
feeds() {
echo "Configuration file \"${config}\" is invalid or does not contain a \"feeds\" function." >&2
echo "See sfeedrc.example for an example." >&2
}
# job counter.
curjobs=0
# signal number received for parent.
signo=0
# SIGINT: signal to interrupt parent.
trap -- "sighandler 2" "INT"
# SIGTERM: signal to terminate parent.
trap -- "sighandler 15" "TERM"
# load config file.
loadconfig "$1"
# fetch feeds and store in temporary directory.
sfeedtmpdir="$(mktemp -d '/tmp/sfeed_XXXXXX')"
# make sure path exists.
mkdir -p "${sfeedpath}"
# fetch feeds specified in config file.
feeds
# wait till all feeds are fetched (concurrently).
[ ${signo} -eq 0 ] && wait
# cleanup temporary files etc.
cleanup
# on signal SIGINT and SIGTERM exit with signal number + 128.
[ ${signo} -ne 0 ] && exit $((signo+128))
exit 0
|
