Bug 1309296

Summary: Bash3 to bash4 behavior change on here doc inside comsub - $( ... )
Product: Red Hat Enterprise Linux 6 Reporter: Paulo Andrade <pandrade>
Component: bashAssignee: Siteshwar Vashisht <svashisht>
Status: CLOSED WONTFIX QA Contact: BaseOS QE - Apps <qe-baseos-apps>
Severity: medium Docs Contact:
Priority: medium    
Version: 6.7   
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: All   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1460933 (view as bug list) Environment:
Last Closed: 2017-06-13 07:49:45 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On:    
Bug Blocks: 1269194, 1460933    
Attachments:
Description Flags
comsub-eof.sh
none
bash-4.2-heredoc-paren-delim.patch none

Description Paulo Andrade 2016-02-17 12:10:38 UTC 
Created attachment 1127918 [details]
comsub-eof.sh

In rhel5, the test case would work and not produce any
warnings. In rhel6 or newer it fails.

  Some users have scripts that rely on this behavior, that
did work on previous versions of bash, and works with old
and current versions of ksh.

  This is an inconsistency of $() versus ``, as with back
tildes it works with current bash version.

  The attached test case is bash/tests/comsub-eof4.sub and
bash/tests/comsub-eof5.sub that explicitly test for the
failure. *But* in bash/parse.y there is also a comment
about supporting this feature:

"""
      /* XXX -- possibly allow here doc to be delimited by ending right
	 paren. */
      if ((tflags & LEX_INHEREDOC) && ch == close && count == 1)
	{
	  int tind;
/*itrace("parse_comsub: in here doc, ch == close, retind - firstind = %d hdlen = %d retind = %d", retind-lex_firstind, hdlen, retind);*/
	  tind = lex_firstind;
	  while ((tflags & LEX_STRIPDOC) && ret[tind] == '\t')
"""
Comment 1 Paulo Andrade 2016-02-17 12:13:37 UTC 
Created attachment 1127922 [details]
bash-4.2-heredoc-paren-delim.patch

This patch, built and tested on rhel7 corrects the issue.

Note that while the patch should be fully functional, and
tests quite a lot of the parser state, it should be possible
to write a simpler one, but I preferred to make a chain of
tests to avoid it being triggered on non matching conditions.