fix: accept a destination inside the device, and say so in --help
The script required the destination to be its own mount point, while the documentation and its own usage text both told the user to pass /media/IPOD/Music. The documented invocation was rejected. A subdirectory is the better target, so the guard was what was wrong. --delete is confined to it, and the device path budget is now derived from it -- the part of the destination below its mount point -- rather than configured, so the budget cannot disagree with where the files are actually going. The check that matters is that the destination sits on a FAT filesystem, which is also what catches an unmounted device: /media/IPOD/Music then resolves to the host's own root filesystem, and emptying that is the outcome all of these guards exist to prevent. Three further faults found while testing the guards rather than reasoning about them: Stripping the trailing slash from "/" left an empty string, so the guard refusing the host root never fired and the user got "destination is not a directory" instead. die() printed only its first argument, so the second half of the non-FAT message -- the half saying to check whether the device is mounted -- was silently dropped. --help was not handled at all. Only -h reached the usage text, and it exited 2 to stderr, which is right for misuse and wrong for someone asking a question. Help now goes to stdout and exits zero. The usage text carries the guidance rather than only the README, since the question it answers is asked at the terminal.
This commit is contained in:
Emma Thorpe
+56
-11
@@ -12,7 +12,13 @@
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set -euo pipefail
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usage() {
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cat >&2 <<'USAGE'
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# Help goes to stdout and exits clean; misuse goes to stderr and does not.
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local stream=2 code=2
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if [ "${1:-}" = "help" ]; then
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stream=1
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code=0
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fi
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cat >&"$stream" <<'USAGE'
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usage: sync-to-ipod.sh [options] <mirror> <destination>
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-n dry run; show what would change and touch nothing
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@@ -24,34 +30,60 @@ Submitting scrobbles needs LASTFM_API_KEY and LASTFM_API_SECRET; it is skipped
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with a note when they are unset. Scrobbling is a write method and needs the
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secret, unlike the read-only calls elsewhere in these projects.
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The destination must be a mounted FAT filesystem. Reach it with the Apple
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firmware's disk mode: Menu+Select to reboot, then immediately Select+Play.
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The mirror is the directory holding the artist folders. The destination is
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where those folders should end up on the device -- not the card root, unless
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that is genuinely where you want them:
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sync-to-ipod.sh /mnt/tank/media/music-mp3 /media/IPOD/Music
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A subdirectory is the better target: --delete is confined to it, and the path
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budget is derived from it, since the device's 260-character limit counts the
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whole path as the device sees it. /.rockbox and the scrobbler logs are never
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deleted wherever you point this.
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The destination must be on a mounted FAT filesystem. That check is also what
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catches an unmounted device: /media/IPOD/Music then resolves to the host's own
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root filesystem, and this refuses to empty that.
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Reach the device with the Apple firmware's disk mode: Menu+Select to reboot,
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then immediately Select+Play. Power off afterwards by holding Play.
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USAGE
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exit 2
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exit "$code"
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}
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dry_run=false
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force=false
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unmount=true
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scrobble=true
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for argument in "$@"; do
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[ "$argument" = "--help" ] && usage help
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done
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while getopts ":nfSUh" option; do
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case "$option" in
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n) dry_run=true ;;
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f) force=true ;;
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S) scrobble=false ;;
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U) unmount=false ;;
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h) usage help ;;
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*) usage ;;
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esac
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done
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shift $((OPTIND - 1))
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[ $# -eq 2 ] || usage
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# Trailing slashes are stripped for tidiness, but stripping one from "/" leaves
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# an empty string, and the guard below would then never see the root it is
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# there to refuse.
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mirror=${1%/}
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mirror=${mirror:-/}
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destination=${2%/}
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destination=${destination:-/}
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here=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
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die() {
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printf 'sync-to-ipod: %s\n' "$1" >&2
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# Every argument, not just the first: the second half of a message is
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# usually the half that says what to do about it.
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printf 'sync-to-ipod: %s\n' "$*" >&2
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exit 1
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}
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@@ -59,28 +91,41 @@ die() {
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[ -n "$(ls -A "$mirror")" ] || die "mirror $mirror is empty; refusing to mirror nothing"
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[ -d "$destination" ] || die "destination $destination is not a directory"
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# --delete makes every one of these load-bearing. A destination that is not its
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# own mount point means the path is wrong, and emptying the wrong directory is
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# not a mistake that announces itself.
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# --delete makes every one of these load-bearing. Emptying the wrong directory
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# is not a mistake that announces itself.
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case "$destination" in
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"" | "/" | "$HOME") die "refusing to sync onto $destination" ;;
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esac
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[ "$(readlink -f "$mirror")" != "$(readlink -f "$destination")" ] ||
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die "mirror and destination are the same directory"
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mountpoint -q -- "$destination" || die "$destination is not a mount point"
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# The filesystem the destination sits on, which is the check that matters: a
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# subdirectory of the card is a perfectly good target, and is the better one,
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# because --delete is then confined to it. Being FAT is also what proves the
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# card is mounted at all -- an unmounted /media/IPOD/Music resolves to the
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# host's own root filesystem, and this refuses to empty that.
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filesystem=$(findmnt -no FSTYPE --target "$destination")
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mounted_on=$(findmnt -no TARGET --target "$destination")
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case "$filesystem" in
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vfat | exfat) ;;
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*)
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$force || die "$destination is $filesystem, not FAT; pass -f if that is deliberate"
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$force ||
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die "$destination is on a $filesystem filesystem, not FAT." \
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"Is the device mounted? Pass -f if this is deliberate."
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printf 'sync-to-ipod: destination is %s, not FAT\n' "$filesystem" >&2
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;;
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esac
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# What the device will call this directory, which is what its path limit
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# applies to. Derived rather than configured, so it cannot disagree with where
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# the files are actually going.
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device_prefix=${destination#"$mounted_on"}
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device_prefix="/${device_prefix#/}"
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printf 'sync-to-ipod: the device will see this as %s\n' "$device_prefix" >&2
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if $force; then
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printf 'sync-to-ipod: skipping the FAT32 check\n' >&2
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elif ! python3 "$here/check_fat32.py" "$mirror"; then
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elif ! python3 "$here/check_fat32.py" --device-prefix "$device_prefix" "$mirror"; then
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die "the mirror holds paths FAT32 will not take; run music-mirror with --fat32-safe"
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fi
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