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81 lines
1.7 KiB
Bash
81 lines
1.7 KiB
Bash
#!/bin/sh
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set -eu
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realpath_canonical() {
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# resolve symlink (if there is one) and use $@ to detect symlink loops
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while [ -L "$1" ] && target=$(readlink -- "$1"); do
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REPLY=$(dirname "$1")
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# Resolve relative to symlink's directory
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if [ "$REPLY" = "." ]; then
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REPLY=$target
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else
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case "$target" in
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/*)
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REPLY=$target;;
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*)
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REPLY=$REPLY/$target;;
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esac
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fi
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# Break out if we found a symlink loop
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for target in "$@"; do [ "$REPLY" = "$target" ] && break 2; done
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# Add to the loop-detect list and tail-recurse
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set -- "$REPLY" "$@"
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done
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# recurse unless root
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REPLY=$(dirname "$1")
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if [ "$REPLY" != "/" ] && [ "$REPLY" != "." ]; then
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REPLY=$(realpath_canonical "$REPLY");
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fi
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# set $1 to dirname and $2 to basename
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set -- "$REPLY" "$(basename "$1")"
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# combine canon parent w/basename
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REPLY=$PWD
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while [ $# -gt 0 ]; do
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# handle case of component starting with double slash and no
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# other slashes separately because it cannot be solved by
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# globbing
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if echo "$1" | grep -E '^//[^/]*$' >/dev/null 2>&1; then
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REPLY=//
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first=$(echo "$1" | cut -c3-)
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shift
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set -- "$first" "$@"
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continue
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fi
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# all other cases can be expressed by globbing
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case $1 in
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/*)
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REPLY=/
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first=$(echo "$1" | sed -e 's/^\/\+//')
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shift
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set -- "$first" "$@"
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;;
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*/*)
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front=${1%%/*}
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back=$(echo "$1" | sed -e "s/^$front\\/\\+//")
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shift
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set -- "$front" "$back" "$@"
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;;
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''|.)
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shift
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;;
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..)
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REPLY=$(dirname "$REPLY")
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shift
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;;
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*)
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REPLY="${REPLY%/}/$1"
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shift
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;;
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esac
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done
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echo "$REPLY"
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}
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if [ $# -ne 1 ]; then
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echo "usage: $0 path"
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exit 1
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fi
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realpath_canonical "$1"
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