Fixed bug #55131: --regexp --recstart hangs. Passes testsuite.

src/parallel

@@ -526,10 +526,16 @@ sub spreadstdin {
 	      # (?!negative lookahead) is needed to avoid backtracking
 	      # See: https://unix.stackexchange.com/questions/439356/
 	      while($buf =~
-		    /# From start up till recend
-		    ^((?:(?!$recend$recstart).)*?$recend
+		    /(
+		    # Either recstart or at least one char from start
+		    ^(?: $recstart | .)
+		    # followed something
+		    (?:(?!$recend$recstart).)*?
+		    # and then recend
+		    $recend
 		    # Then n-1 times recstart.*recend
-		    (?:$recstart(?:(?!$recend$recstart).)*?$recend){$read_n_lines})
+		    (?:$recstart(?:(?!$recend$recstart).)*?$recend){$read_n_lines}
+		    )
 		    # Followed by recstart
 		    (?=$recstart)/osx) {
 		  $anything_written +=
@@ -1559,7 +1565,7 @@ sub check_invalid_option_combinations {
 
 sub init_globals {
     # Defaults:
-    $Global::version = 20181124;
+    $Global::version = 20181202;
     $Global::progname = 'parallel';
     $Global::infinity = 2**31;
     $Global::debug = 0;

testsuite/tests-to-run/parallel-local-0.3s.sh

@@ -664,7 +664,9 @@ par_X_eta_div_zero() {
     # We do not care how long it took
     seq 2 | stdout parallel -X --eta echo |
 	grep -E -v 'ETA:.*AVG' |
-	perl -pe 's/\d+/0/g'
+	perl -pe 's/\d+/0/g' |
+	perl -pe 's/Comp.* to complete//' |
+	perl -ne '/../ and print'
 }
 
 par_parcat_args_stdin() {
@@ -777,7 +779,12 @@ par_slow_pipe_regexp() {
     echo "### bug #53718: --pipe --regexp -N blocks"
     echo This should take a few ms, but took more than 2 hours
     seq 54000 80000 |
-	timeout -k 1 60 parallel -N1000 --regexp --pipe --recstart 4 --recend 5 -k wc
+	parallel -N1000 --regexp --pipe --recstart 4 --recend 5 -k wc
+    echo "### These should give same output"
+    seq 54000 80000 |
+	parallel -N1000 --regexp --pipe --recstart 4 --recend 5 -k cat |
+	md5sum
+    seq 54000 80000 | md5sum
 }
 
 par_results() {
@@ -865,7 +872,15 @@ par_space_envvar() {
     export PARALLEL=" -v" && parallel echo ::: 'space in envvar OK'
 }
 
+par_pipe_N1_regexp() {
+    echo 'bug #55131: --regexp --recstart hangs'
+    echo "These should give the same"
+    printf 'begin\n%send\n' '' a b c |
+        parallel -kN1 --recstart 'begin\n' --pipe --regexp echo JOB{#}\;cat\;echo END
+    printf 'begin\n%send\n' '' a b c |
+        parallel -kN1 --recstart 'begin\n' --pipe          echo JOB{#}\;cat\;echo END
+}
 
 export -f $(compgen -A function | grep par_)
 compgen -A function | grep par_ | LC_ALL=C sort |
-    parallel -j6 --tag -k --joblog +/tmp/jl-`basename $0` '{} 2>&1'
+    parallel --timeout 20 -j6 --tag -k --joblog +/tmp/jl-`basename $0` '{} 2>&1'

testsuite/wanted-results/parallel-local-0.3s

@@ -1251,7 +1251,6 @@ par_PARALLEL_ENV	OK as file
 par_PARALLEL_ENV	### PARALLEL_ENV as fifo
 par_PARALLEL_ENV	OK as fifo
 par_X_eta_div_zero	### bug #34422: parallel -X --eta crashes with div by zero
-par_X_eta_div_zero	0
 par_X_eta_div_zero	Computers / CPU cores / Max jobs to run
 par_X_eta_div_zero	0:local / 0 / 0
 par_append_joblog	### can you append to a joblog using +
@@ -1391,6 +1390,40 @@ par_parcat_rm	bug #51691: parcat --rm remove fifo when opened
 par_parcat_rm	OK1
 par_parcat_rm	OK file removed
 par_perlexpr_with_newline	Perl expression spanning 2 lines
+par_pipe_N1_regexp	bug #55131: --regexp --recstart hangs
+par_pipe_N1_regexp	These should give the same
+par_pipe_N1_regexp	JOB1
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	end
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB2
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	aend
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB3
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	bend
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB4
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	cend
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB1
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	end
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB2
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	aend
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB3
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	bend
+par_pipe_N1_regexp	END
+par_pipe_N1_regexp	JOB4
+par_pipe_N1_regexp	begin
+par_pipe_N1_regexp	cend
+par_pipe_N1_regexp	END
 par_pipe_no_command	### --pipe without command
 par_pipe_no_command	parallel: Error: --pipe/--pipepart must have a command to pipe into (e.g. 'cat').
 par_pipe_recend	bug #54328: --pipe --recend  blocks
@@ -1481,8 +1514,11 @@ par_retries_replacement_string	33
 par_retries_replacement_string	33
 par_slow_pipe_regexp	### bug #53718: --pipe --regexp -N blocks
 par_slow_pipe_regexp	This should take a few ms, but took more than 2 hours
-par_slow_pipe_regexp	    979     980    5875
-par_slow_pipe_regexp	  25022   25022  150131
+par_slow_pipe_regexp	    980     981    5881
+par_slow_pipe_regexp	  25021   25021  150125
+par_slow_pipe_regexp	### These should give same output
+par_slow_pipe_regexp	6e72d7f86f6a423b9a7fa97630587815  -
+par_slow_pipe_regexp	6e72d7f86f6a423b9a7fa97630587815  -
 par_space_envvar	### bug: --gnu was ignored if env var started with space: PARALLEL=' --gnu'
 par_space_envvar	echo 'space in envvar OK'
 par_space_envvar	space in envvar OK

testsuite/wanted-results/parallel-local23

@@ -61,7 +61,7 @@ echo '### Check that 4 processes are really used'
 echo '### --version must have higher priority than retired options'
 ### --version must have higher priority than retired options
   $NICEPAR --version -g -Y -U -W -T | tail
-GNU parallel 20181124
+GNU parallel 20181202
 Copyright (C) 2007-2018 Ole Tange and Free Software Foundation, Inc.
 License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
 This is free software: you are free to change and redistribute it.