| 1 | #! /bin/sh |
| 2 | |
| 3 | ## This sed(1) script takes key/value pairs in tripe-admin(5) format as |
| 4 | ## input; it writes sh(1) variable assignments as output. The idea is that |
| 5 | ## you can say |
| 6 | ## |
| 7 | ## eval $(tripectl algs | sed "$keysubst") |
| 8 | ## |
| 9 | ## and have shell variables set from the output of the command. The shell |
| 10 | ## variable names are worked out from the key names, with sequences of |
| 11 | ## nonalphanumerics replaced by single underscores. Quoting is handled |
| 12 | ## correctly, both on input and output. |
| 13 | ## |
| 14 | ## Theory of operation: firstly, ! and @ characters in the input are replaced |
| 15 | ## by !e and !a respectively; this is a reversible transformation, which we |
| 16 | ## undo at the end. We now know that the input does not contain @. We use a |
| 17 | ## string of the form [lr][nqQ]@ as a cursor to move across the input from |
| 18 | ## left to right. The letters on the left of the @ are state markers: l |
| 19 | ## means left of =, r means right; n means not in quotes; q means single- |
| 20 | ## quoted; Q means double-quoted. |
| 21 | ## |
| 22 | ## This is a particularly awful hack. I'm so sorry. |
| 23 | keysubst=' |
| 24 | ## Initial transformation. |
| 25 | s/!/!e/g'$p' |
| 26 | s/@/!a/g'$p' |
| 27 | |
| 28 | ## Initial state: left-hand side, not quoted |
| 29 | s/^/ln@/'$p' |
| 30 | |
| 31 | :loop |
| 32 | ## Reached the end: exit. |
| 33 | /@$/ b end |
| 34 | |
| 35 | ## Enter or leave quoted state as necessary. |
| 36 | s/\(.\)n@'\''/\1q@/'$p' |
| 37 | s/\(.\)n@"/\1Q@/'$p' |
| 38 | s/\(.\)q@'\''/\1n@/'$p' |
| 39 | s/\(.\)Q@"/\1n@/'$p' |
| 40 | t loop |
| 41 | |
| 42 | ## Leave backslashed things alone. |
| 43 | /\(..\)@\\/ { |
| 44 | s//\1@/ |
| 45 | b lit |
| 46 | } |
| 47 | |
| 48 | ## Unquotes spaces delimit key/value pairs. |
| 49 | s/\(rn\)@[ ]\+/'\'' ln@/'$p' |
| 50 | |
| 51 | ## An = sign separates left and right sides. |
| 52 | s/l\(.\)@=/='\''r\1@/'$p' |
| 53 | |
| 54 | ## Single quotes on the right-hand side need special care. |
| 55 | t loop |
| 56 | s/r\(.\)@'\'/\''\\'\'\''r\1@/'$p' |
| 57 | |
| 58 | ## Sequences of alphanumerics are always easy. |
| 59 | s/\(..\)@\([[:alnum:]]\+\)/\2\1@/'$p' |
| 60 | |
| 61 | :lit |
| 62 | ## Convert bad left-hand-side characters to underscores. |
| 63 | t loop |
| 64 | s/l\(.\)@\(!.\|[^=![:alnum:]]\)\+/_l\1@/'$p' |
| 65 | |
| 66 | ## Convert sequences of nonproblematic right-hand-side characters. |
| 67 | t loop |
| 68 | s/\(r.\)@\([^ '\''"`]\+\)/\2\1@/'$p' |
| 69 | |
| 70 | ## And anything else is probably OK. |
| 71 | s/\(..\)@\(.\)/\2\1@/'$p' |
| 72 | b loop |
| 73 | |
| 74 | :end |
| 75 | ## Unquote the end appropriately. |
| 76 | s/r.@/'\''/'$p' |
| 77 | s/..@//'$p' |
| 78 | |
| 79 | ## And undo the initial transformation. |
| 80 | s/!a/@/g'$p' |
| 81 | s/!e/!/g'$p' |
| 82 | ' |
| 83 | |
| 84 | sed "$keysubst" |