| blob | 8544df38dfc0c557120a8a250529147edbc3d2a4 |
1 #------------------------------------------------------------------------------
2 # Detect broken &&-chains in tests.
3 #
4 # At present, only &&-chains in subshells are examined by this linter;
5 # top-level &&-chains are instead checked directly by the test framework. Like
6 # the top-level &&-chain linter, the subshell linter (intentionally) does not
7 # check &&-chains within {...} blocks.
8 #
9 # Checking for &&-chain breakage is done line-by-line by pure textual
10 # inspection.
11 #
12 # Incomplete lines (those ending with "\") are stitched together with following
13 # lines to simplify processing, particularly of "one-liner" statements.
14 # Top-level here-docs are swallowed to avoid false positives within the
15 # here-doc body, although the statement to which the here-doc is attached is
16 # retained.
17 #
18 # Heuristics are used to detect end-of-subshell when the closing ")" is cuddled
19 # with the final subshell statement on the same line:
20 #
21 # (cd foo &&
22 # bar)
23 #
24 # in order to avoid misinterpreting the ")" in constructs such as "x=$(...)"
25 # and "case $x in *)" as ending the subshell.
26 #
27 # Lines missing a final "&&" are flagged with "?!AMP?!", and lines which chain
28 # commands with ";" internally rather than "&&" are flagged "?!SEMI?!". A line
29 # may be flagged for both violations.
30 #
31 # Detection of a missing &&-link in a multi-line subshell is complicated by the
32 # fact that the last statement before the closing ")" must not end with "&&".
33 # Since processing is line-by-line, it is not known whether a missing "&&" is
34 # legitimate or not until the _next_ line is seen. To accommodate this, within
35 # multi-line subshells, each line is stored in sed's "hold" area until after
36 # the next line is seen and processed. If the next line is a stand-alone ")",
37 # then a missing "&&" on the previous line is legitimate; otherwise a missing
38 # "&&" is a break in the &&-chain.
39 #
40 # (
41 # cd foo &&
42 # bar
43 # )
44 #
45 # In practical terms, when "bar" is encountered, it is flagged with "?!AMP?!",
46 # but when the stand-alone ")" line is seen which closes the subshell, the
47 # "?!AMP?!" violation is removed from the "bar" line (retrieved from the "hold"
48 # area) since the final statement of a subshell must not end with "&&". The
49 # final line of a subshell may still break the &&-chain by using ";" internally
50 # to chain commands together rather than "&&", so "?!SEMI?!" is never removed
51 # from a line (even though "?!AMP?!" might be).
52 #
53 # Care is taken to recognize the last _statement_ of a multi-line subshell, not
54 # necessarily the last textual _line_ within the subshell, since &&-chaining
55 # applies to statements, not to lines. Consequently, blank lines, comment
56 # lines, and here-docs are swallowed (but not the command to which the here-doc
57 # is attached), leaving the last statement in the "hold" area, not the last
58 # line, thus simplifying &&-link checking.
59 #
60 # The final statement before "done" in for- and while-loops, and before "elif",
61 # "else", and "fi" in if-then-else likewise must not end with "&&", thus
62 # receives similar treatment.
63 #
64 # Swallowing here-docs with arbitrary tags requires a bit of finesse. When a
65 # line such as "cat <<EOF >out" is seen, the here-doc tag is moved to the front
66 # of the line enclosed in angle brackets as a sentinel, giving "<EOF>cat >out".
67 # As each subsequent line is read, it is appended to the target line and a
68 # (whitespace-loose) back-reference match /^<(.*)>\n\1$/ is attempted to see if
69 # the content inside "<...>" matches the entirety of the newly-read line. For
70 # instance, if the next line read is "some data", when concatenated with the
71 # target line, it becomes "<EOF>cat >out\nsome data", and a match is attempted
72 # to see if "EOF" matches "some data". Since it doesn't, the next line is
73 # attempted. When a line consisting of only "EOF" (and possible whitespace) is
74 # encountered, it is appended to the target line giving "<EOF>cat >out\nEOF",
75 # in which case the "EOF" inside "<...>" does match the text following the
76 # newline, thus the closing here-doc tag has been found. The closing tag line
77 # and the "<...>" prefix on the target line are then discarded, leaving just
78 # the target line "cat >out".
79 #
80 # To facilitate regression testing (and manual debugging), a ">" annotation is
81 # applied to the line containing ")" which closes a subshell, ">>" to a line
82 # closing a nested subshell, and ">>>" to a line closing both at once. This
83 # makes it easy to detect whether the heuristics correctly identify
84 # end-of-subshell.
85 #------------------------------------------------------------------------------
87 # incomplete line -- slurp up next line
88 :squash
89 /\\$/ {
90 N
91 s/\\\n//
92 bsquash
93 }
95 # here-doc -- swallow it to avoid false hits within its body (but keep the
96 # command to which it was attached)
97 /<<[ ]*[-\\']*[A-Za-z0-9_]/ {
98 s/^\(.*\)<<[ ]*[-\\']*\([A-Za-z0-9_][A-Za-z0-9_]*\)'*/<\2>\1<</
99 s/[ ]*<<//
100 :hereslurp
101 N
102 /^<\([^>]*\)>.*\n[ ]*\1[ ]*$/!{
103 s/\n.*$//
104 bhereslurp
105 }
106 s/^<[^>]*>//
107 s/\n.*$//
108 }
110 # one-liner "(...) &&"
111 /^[ ]*!*[ ]*(..*)[ ]*&&[ ]*$/boneline
113 # same as above but without trailing "&&"
114 /^[ ]*!*[ ]*(..*)[ ]*$/boneline
116 # one-liner "(...) >x" (or "2>x" or "<x" or "|x" or "&"
117 /^[ ]*!*[ ]*(..*)[ ]*[0-9]*[<>|&]/boneline
119 # multi-line "(...\n...)"
120 /^[ ]*(/bsubshell
122 # innocuous line -- print it and advance to next line
123 b
125 # found one-liner "(...)" -- mark suspect if it uses ";" internally rather than
126 # "&&" (but not ";" in a string)
127 :oneline
128 /;/{
129 /"[^"]*;[^"]*"/!s/^/?!SEMI?!/
130 }
131 b
133 :subshell
134 # bare "(" line?
135 /^[ ]*([ ]*$/ {
136 # stash for later printing
137 h
138 bnextline
139 }
140 # "(..." line -- split off and stash "(", then process "..." as its own line
141 x
142 s/.*/(/
143 x
144 s/(//
145 bslurp
147 :nextline
148 N
149 s/.*\n//
151 :slurp
152 # incomplete line "...\"
153 /\\$/bincomplete
154 # multi-line quoted string "...\n..."?
155 /"/bdqstring
156 # multi-line quoted string '...\n...'? (but not contraction in string "it's")
157 /'/{
158 /"[^'"]*'[^'"]*"/!bsqstring
159 }
160 :folded
161 # here-doc -- swallow it
162 /<<[ ]*[-\\']*[A-Za-z0-9_]/bheredoc
163 # comment or empty line -- discard since final non-comment, non-empty line
164 # before closing ")", "done", "elsif", "else", or "fi" will need to be
165 # re-visited to drop "suspect" marking since final line of those constructs
166 # legitimately lacks "&&", so "suspect" mark must be removed
167 /^[ ]*#/bnextline
168 /^[ ]*$/bnextline
169 # in-line comment -- strip it (but not "#" in a string, Bash ${#...} array
170 # length, or Perforce "//depot/path#42" revision in filespec)
171 /[ ]#/{
172 /"[^"]*#[^"]*"/!s/[ ]#.*$//
173 }
174 # one-liner "case ... esac"
175 /^[ ]*case[ ]*..*esac/bcheckchain
176 # multi-line "case ... esac"
177 /^[ ]*case[ ]..*[ ]in/bcase
178 # multi-line "for ... done" or "while ... done"
179 /^[ ]*for[ ]..*[ ]in/bcontinue
180 /^[ ]*while[ ]/bcontinue
181 /^[ ]*do[ ]/bcontinue
182 /^[ ]*do[ ]*$/bcontinue
183 /;[ ]*do/bcontinue
184 /^[ ]*done[ ]*&&[ ]*$/bdone
185 /^[ ]*done[ ]*$/bdone
186 /^[ ]*done[ ]*[<>|]/bdone
187 /^[ ]*done[ ]*)/bdone
188 /||[ ]*exit[ ]/bcontinue
189 /||[ ]*exit[ ]*$/bcontinue
190 # multi-line "if...elsif...else...fi"
191 /^[ ]*if[ ]/bcontinue
192 /^[ ]*then[ ]/bcontinue
193 /^[ ]*then[ ]*$/bcontinue
194 /;[ ]*then/bcontinue
195 /^[ ]*elif[ ]/belse
196 /^[ ]*elif[ ]*$/belse
197 /^[ ]*else[ ]/belse
198 /^[ ]*else[ ]*$/belse
199 /^[ ]*fi[ ]*&&[ ]*$/bdone
200 /^[ ]*fi[ ]*$/bdone
201 /^[ ]*fi[ ]*[<>|]/bdone
202 /^[ ]*fi[ ]*)/bdone
203 # nested one-liner "(...) &&"
204 /^[ ]*(.*)[ ]*&&[ ]*$/bcheckchain
205 # nested one-liner "(...)"
206 /^[ ]*(.*)[ ]*$/bcheckchain
207 # nested one-liner "(...) >x" (or "2>x" or "<x" or "|x")
208 /^[ ]*(.*)[ ]*[0-9]*[<>|]/bcheckchain
209 # nested multi-line "(...\n...)"
210 /^[ ]*(/bnest
211 # multi-line "{...\n...}"
212 /^[ ]*{/bblock
213 # closing ")" on own line -- exit subshell
214 /^[ ]*)/bclosesolo
215 # "$((...))" -- arithmetic expansion; not closing ")"
216 /\$(([^)][^)]*))[^)]*$/bcheckchain
217 # "$(...)" -- command substitution; not closing ")"
218 /\$([^)][^)]*)[^)]*$/bcheckchain
219 # multi-line "$(...\n...)" -- command substitution; treat as nested subshell
220 /\$([^)]*$/bnest
221 # "=(...)" -- Bash array assignment; not closing ")"
222 /=(/bcheckchain
223 # closing "...) &&"
224 /)[ ]*&&[ ]*$/bclose
225 # closing "...)"
226 /)[ ]*$/bclose
227 # closing "...) >x" (or "2>x" or "<x" or "|x")
228 /)[ ]*[<>|]/bclose
229 :checkchain
230 # mark suspect if line uses ";" internally rather than "&&" (but not ";" in a
231 # string and not ";;" in one-liner "case...esac")
232 /;/{
233 /;;/!{
234 /"[^"]*;[^"]*"/!s/^/?!SEMI?!/
235 }
236 }
237 # line ends with pipe "...|" -- valid; not missing "&&"
238 /|[ ]*$/bcontinue
239 # missing end-of-line "&&" -- mark suspect
240 /&&[ ]*$/!s/^/?!AMP?!/
241 :continue
242 # retrieve and print previous line
243 x
244 n
245 bslurp
247 # found incomplete line "...\" -- slurp up next line
248 :incomplete
249 N
250 s/\\\n//
251 bslurp
253 # check for multi-line double-quoted string "...\n..." -- fold to one line
254 :dqstring
255 # remove all quote pairs
256 s/"\([^"]*\)"/@!\1@!/g
257 # done if no dangling quote
258 /"/!bdqdone
259 # otherwise, slurp next line and try again
260 N
261 s/\n//
262 bdqstring
263 :dqdone
264 s/@!/"/g
265 bfolded
267 # check for multi-line single-quoted string '...\n...' -- fold to one line
268 :sqstring
269 # remove all quote pairs
270 s/'\([^']*\)'/@!\1@!/g
271 # done if no dangling quote
272 /'/!bsqdone
273 # otherwise, slurp next line and try again
274 N
275 s/\n//
276 bsqstring
277 :sqdone
278 s/@!/'/g
279 bfolded
281 # found here-doc -- swallow it to avoid false hits within its body (but keep
282 # the command to which it was attached)
283 :heredoc
284 s/^\(.*\)<<[ ]*[-\\']*\([A-Za-z0-9_][A-Za-z0-9_]*\)'*/<\2>\1<</
285 s/[ ]*<<//
286 :hereslurpsub
287 N
288 /^<\([^>]*\)>.*\n[ ]*\1[ ]*$/!{
289 s/\n.*$//
290 bhereslurpsub
291 }
292 s/^<[^>]*>//
293 s/\n.*$//
294 bfolded
296 # found "case ... in" -- pass through untouched
297 :case
298 x
299 n
300 /^[ ]*esac/bslurp
301 bcase
303 # found "else" or "elif" -- drop "suspect" from final line before "else" since
304 # that line legitimately lacks "&&"
305 :else
306 x
307 s/?!AMP?!//
308 x
309 bcontinue
311 # found "done" closing for-loop or while-loop, or "fi" closing if-then -- drop
312 # "suspect" from final contained line since that line legitimately lacks "&&"
313 :done
314 x
315 s/?!AMP?!//
316 x
317 # is 'done' or 'fi' cuddled with ")" to close subshell?
318 /done.*)/bclose
319 /fi.*)/bclose
320 bcheckchain
322 # found nested multi-line "(...\n...)" -- pass through untouched
323 :nest
324 x
325 :nestslurp
326 n
327 # closing ")" on own line -- stop nested slurp
328 /^[ ]*)/bnestclose
329 # comment -- not closing ")" if in comment
330 /^[ ]*#/bnestcontinue
331 # "$((...))" -- arithmetic expansion; not closing ")"
332 /\$(([^)][^)]*))[^)]*$/bnestcontinue
333 # "$(...)" -- command substitution; not closing ")"
334 /\$([^)][^)]*)[^)]*$/bnestcontinue
335 # closing "...)" -- stop nested slurp
336 /)/bnestclose
337 :nestcontinue
338 x
339 bnestslurp
340 :nestclose
341 s/^/>>/
342 # is it "))" which closes nested and parent subshells?
343 /)[ ]*)/bslurp
344 bcheckchain
346 # found multi-line "{...\n...}" block -- pass through untouched
347 :block
348 x
349 n
350 # closing "}" -- stop block slurp
351 /}/bcheckchain
352 bblock
354 # found closing ")" on own line -- drop "suspect" from final line of subshell
355 # since that line legitimately lacks "&&" and exit subshell loop
356 :closesolo
357 x
358 s/?!AMP?!//
359 p
360 x
361 s/^/>/
362 b
364 # found closing "...)" -- exit subshell loop
365 :close
366 x
367 p
368 x
369 s/^/>/
370 b