Mini Shell

#!/usr/bin/sh
# url-lib.sh - functions for handling URLs (file fetching etc.)
#
# Authors:
#   Will Woods <wwoods@redhat.com>

type mkuniqdir > /dev/null 2>&1 || . /lib/dracut-lib.sh

# fetch_url URL [OUTFILE]
#   fetch the given URL to a locally-visible location.
#   if OUTFILE is given, the URL will be fetched to that filename,
#   overwriting it if present.
#   If the URL is something mountable (e.g. nfs://) and no OUTFILE is given,
#   the server will be left mounted until pre-pivot.
#   the return values are as follows:
#   0: success
#   253: unknown error (file missing)
#   254: unhandled URL scheme / protocol
#   255: bad arguments / unparseable URLs
#   other: fetch command failure (whatever curl/mount/etc return)
fetch_url() {
    local url="$1" outloc="$2"
    local handler
    handler="$(get_url_handler "$url")"
    [ -n "$handler" ] || return 254
    [ -n "$url" ] || return 255
    "$handler" "$url" "$outloc"
}

# get_url_handler URL
#   returns the first HANDLERNAME corresponding to the URL's scheme
get_url_handler() {
    local scheme="${1%%:*}" item=""
    for item in $url_handler_map; do
        [ "$scheme" = "${item%%:*}" ] && echo "${item#*:}" && return 0
    done
    return 1
}

# add_url_handler HANDLERNAME SCHEME [SCHEME...]
#   associate the named handler with the named scheme(s).
add_url_handler() {
    local handler="$1"
    shift
    local schemes="$*" scheme=""
    set --
    for scheme in $schemes; do
        [ "$(get_url_handler "$scheme")" = "$handler" ] && continue
        set -- "$@" "$scheme:$handler"
    done
    set -- "$@" "$url_handler_map" # add new items to *front* of list
    url_handler_map="$*"
}

### HTTP, HTTPS, FTP #################################################

export CURL_HOME="/run/initramfs/url-lib"
mkdir -p $CURL_HOME
curl_args="--globoff --location --retry 3 --retry-connrefused --fail --show-error"
getargbool 0 rd.noverifyssl && curl_args="$curl_args --insecure"

proxy=$(getarg proxy=)
[ -n "$proxy" ] && curl_args="$curl_args --proxy $proxy"

curl_fetch_url() {
    local url="$1" outloc="$2"
    echo "$url" > /proc/self/fd/0
    if [ -n "$outloc" ]; then
        # shellcheck disable=SC2086
        curl $curl_args --output "$outloc" -- "$url" || return $?
    else
        local outdir
        outdir="$(mkuniqdir /tmp curl_fetch_url)"
        (
            cd "$outdir" || exit
            # shellcheck disable=SC2086
            curl $curl_args --remote-name "$url" || return $?
        )
        outloc="$outdir/$(ls -A "$outdir")"
    fi
    if ! [ -f "$outloc" ]; then
        warn "Downloading '$url' failed!"
        return 253
    fi
    if [ -z "$2" ]; then echo "$outloc"; fi
}
add_url_handler curl_fetch_url http https ftp tftp

set_http_header() {
    echo "header = \"$1: $2\"" >> $CURL_HOME/.curlrc
}

### TORRENT ##########################################################

ctorrent_args="-E 0 -e 0"

ctorrent_fetch_url() {
    local url="$1" outloc="$2"
    url=${url#*//}
    torrent_outloc="$outloc.torrent"
    echo "$url" > /proc/self/fd/0
    if [ -n "$outloc" ]; then
        # shellcheck disable=SC2086
        curl $curl_args --output "$torrent_outloc" -- "$url" || return $?
    else
        local outdir
        outdir="$(mkuniqdir /tmp torrent_fetch_url)"
        (
            cd "$outdir" || exit
            # shellcheck disable=SC2086
            curl $curl_args --remote-name "$url" || return $?
        )
        torrent_outloc="$outdir/$(ls -A "$outdir")"
        outloc=${torrent_outloc%.*}
    fi
    if ! [ -f "$torrent_outloc" ]; then
        warn "Downloading '$url' failed!"
        return 253
    fi
    # shellcheck disable=SC2086
    ctorrent $ctorrent_args -s "$outloc" "$torrent_outloc" >&2
    if ! [ -f "$outloc" ]; then
        warn "Torrent download of '$url' failed!"
        return 253
    fi
    if [ -z "$2" ]; then echo "$outloc"; fi
}

command -v ctorrent > /dev/null \
    && add_url_handler ctorrent_fetch_url torrent

### NFS ##############################################################

[ -e /lib/nfs-lib.sh ] && . /lib/nfs-lib.sh

nfs_already_mounted() {
    local server="$1" path="$2" s="" p=""
    while read -r src mnt rest || [ -n "$src" ]; do
        splitsep ":" "$src" s p
        p=${p%/}
        if [ "$server" = "$s" ]; then
            if [ "$path" = "$p" ]; then
                echo "$mnt"
            elif str_starts "$path" "$p"; then
                echo "$mnt"/"${path#$p/}"
            fi
        fi
    done < /proc/mounts
}

nfs_fetch_url() {
    local url="$1" outloc="$2" nfs="" server="" path="" options=""
    nfs_to_var "$url" || return 255
    local filepath="${path%/*}" filename="${path##*/}" mntdir=""

    # skip mount if server:/filepath is already mounted
    mntdir=$(nfs_already_mounted "$server" "$filepath")
    if [ -z "$mntdir" ]; then
        local mntdir
        mntdir="$(mkuniqdir /run nfs_mnt)"
        mount_nfs "$nfs:$server:$filepath${options:+:$options}" "$mntdir"
        # lazy unmount during pre-pivot hook
        inst_hook --hook pre-pivot --name 99url-lib-umount-nfs-"$(basename "$mntdir")" umount -l -- "$mntdir"
    fi

    if [ -z "$outloc" ]; then
        outloc="$mntdir/$filename"
    else
        cp -f -- "$mntdir/$filename" "$outloc" || return $?
    fi
    [ -f "$outloc" ] || return 253
    if [ -z "$2" ]; then echo "$outloc"; fi
}
command -v nfs_to_var > /dev/null && add_url_handler nfs_fetch_url nfs nfs4