- printf "$(printf %s "$1" \
- | sed -r '
- s;\\;\\\\;g; :x; s;%([^0-9A-F]);\\045\1;g; tx;
- # Hexadecimal { %00 - %FF } will be transformed to octal { \000 - \377 } for posix printf
- s;%[0123].;&\\0;g; s;%[4567].;&\\1;g; s;%[89AB].;&\\2;g; s;%[CDEF].;&\\3;g;
- s;%[048C][0-7]\\.;&0;g; s;%[048C][89A-F]\\.;&1;g; s;%[159D][0-7]\\.;&2;g; s;%[159D][89A-F]\\.;&3;g;
- s;%[26AE][0-7]\\.;&4;g; s;%[26AE][89A-F]\\.;&5;g; s;%[37BF][0-7]\\.;&6;g; s;%[37BF][89A-F]\\.;&7;g;
- s;%.[08](\\..);\10;g; s;%.[19](\\..);\11;g; s;%.[2A](\\..);\12;g; s;%.[3B](\\..);\13;g;
- s;%.[4C](\\..);\14;g; s;%.[5D](\\..);\15;g; s;%.[6E](\\..);\16;g; s;%.[7F](\\..);\17;g;
- ')"
+ local pfx="$1" in="$2" out
+ # Print out Data encoded as Hex
+ #
+ # Arguments:
+ # pfx - required, prefix for a hex tupel, e.g. "\x", "%" "\", may be empty
+ # in - required, string to be decoded
+ #
+ # anything that does not constitute a tupel of valid Hex numerals
+ # will be copied to the output literally
+
+ while [ "$in" ]; do
+ case $in in
+ "$pfx"[0-9a-fA-F][0-9a-fA-F]*) in="${in#${pfx}}";;
+ \\*) in="${in#?}"; out="${out}\\\\"; continue;;
+ %*) in="${in#?}"; out="${out}%%"; continue;;
+ *) out="${out}${in%"${in#?}"}"; in="${in#?}"; continue;;
+ esac;
+
+ # Hex escapes for printf (e.g. \x41) are not portable
+ # The portable way for Hex output is transforming Hex to Octal
+ # (e.g. \x41 = \101)
+ case $in in
+ [0123]?*) out="${out}\\0";;
+ [4567]?*) out="${out}\\1";;
+ [89aAbB]?*) out="${out}\\2";;
+ [c-fC-F]?*) out="${out}\\3";;
+ esac
+ case $in in
+ [048cC][0-7]*) out="${out}0";;
+ [048cC][89a-fA-F]*) out="${out}1";;
+ [159dD][0-7]*) out="${out}2";;
+ [159dD][89a-fA-F]*) out="${out}3";;
+ [26aAeE][0-7]*) out="${out}4";;
+ [26aAeE][89a-fA-F]*) out="${out}5";;
+ [37bBfF][0-7]*) out="${out}6";;
+ [37bBfF][89a-fA-F]*) out="${out}7";;
+ esac
+ case $in in
+ ?[08]*) out="${out}0";;
+ ?[19]*) out="${out}1";;
+ ?[2aA]*) out="${out}2";;
+ ?[3bB]*) out="${out}3";;
+ ?[4cC]*) out="${out}4";;
+ ?[5dD]*) out="${out}5";;
+ ?[6eE]*) out="${out}6";;
+ ?[7fF]*) out="${out}7";;
+ esac
+ in="${in#?}"
+ in="${in#?}"
+ done
+ printf -- "$out"