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#!/bin/sh
DLCACHE_DIR=${DLCACHE_DIR:-~/.dlcache}
mkdir -p "$DLCACHE_DIR"
_echo() {
echo "$@" 1>&2
}
if [ "$(uname)" = Darwin ]; then
_locked() {
local lockfile="$1"
shift
while ! shlock -p $$ -f $lockfile; do
sleep 0.2
done
$*
rm $lockfile
}
else
_locked() {
local lockfile="$1"
shift
(
flock -w 600 9 || exit 1
$*
) 9>"$lockfile"
}
fi
if [ "$(uname)" = Darwin ]; then
MD5="md5 -r"
else
MD5=md5sum
fi
calcmd5() {
local file="$1"
local md5="$2"
local file_md5=$(${MD5} "$file" | cut -d\ -f1)
test "$md5" = "$file_md5"
}
downloader() {
if [ -n "$(command -v wget)" ]; then
wget -nv "$1" -O $2
elif [ -n "$(command -v curl)" ]; then
curl -L $1 -o $2
else
_echo "$0: neither wget nor curl available!"
return 1
fi
}
download() {
local url="$1"
local _md5="$2"
local basename_url=$(basename ${url})
local target="${3:-${basename_url}}"
[ -f "$target" ] && {
# if our target file exists, check it's md5.
calcmd5 "$target" "$_md5" && {
_echo "$0: target exists, md5 matches."
exit 0
}
}
local filename="$(basename $url)"
[ -f "$DLCACHE_DIR/$filename" ] && {
# if the file exists in cache, check it's md5 and possibly remove it.
if calcmd5 "$DLCACHE_DIR/$filename" "$_md5"; then
_echo "$0: getting \"$url\" from cache"
else
_echo "$0: \"$DLCACHE_DIR/$filename\" has wrong checksum, re-downloading"
rm "$DLCACHE_DIR/$filename"
fi
}
[ ! -f "$DLCACHE_DIR/$filename" ] && {
_echo "$0: downloading \"$url\"..."
downloader "$url" "$DLCACHE_DIR/$filename" || {
_echo "$0: error downloading $url to $DLCACHE_DIR/$filename!"
exit 1
}
_echo "$0: done downloading \"$url\""
}
calcmd5 "$DLCACHE_DIR/$filename" "$_md5" || {
_echo "$0: checksum mismatch!"
exit 1
}
if [ "$target" = "-" ]; then
cat "$DLCACHE_DIR/$filename"
else
cp "$DLCACHE_DIR/$filename" "$target"
fi
}
_locked "$DLCACHE_DIR/$(basename $1).locked" download "$@"