freebsd-src/usr.bin/grep
Kyle Evans 3e2d96ac97 grep: fix -A handling in conjunction with -m match limitation
The basic issue here is that grep, when given -m 1, would stop all
line processing once it hit the match count and exit immediately.  The
problem with exiting immediately is that -A processing only happens when
subsequent lines are processed and do not match.

The fix here is relatively easy; when bsdgrep matches a line, it resets
the 'tail' of the matching context to the value supplied to -A and
dumps anything that's been queued up for -B. After the current line has
been printed and tail is reset, we check our mcount and do what's
needed. Therefore, at the time that we decide we're doing nothing, we
know that 'tail' of the context is correct and we can simply continue
on if there's still more to pick up.

With this change, we still bail out immediately if there's been no -A
flag. If -A was supplied, we signal that we should continue on. However,
subsequent lines will not even bothere to try and process the line.  We
have reached the match count, so even if the next line would match then
we must process it if it hadn't. Thus, the loop in procfile() can
short-circuit and just process the line as a non-match until
procmatches() indicates that it's safe to stop.

A test has been added to reflect both that we should be picking up the
next line and that the next line should be considered a non-match even
if it should have been.

PR:		253350
MFC-after:	3 days
2021-02-08 12:41:22 -06:00
..
tests grep: tests: stop testing for a nonexistent version of grep 2020-12-25 15:16:33 -06:00
file.c
grep.1 grep: turn off -w if -x is specified 2021-02-04 20:59:43 -06:00
grep.c grep: turn off -w if -x is specified 2021-02-04 20:59:43 -06:00
grep.h grep: replace the internal queue with a ring buffer 2020-12-09 05:27:45 +00:00
Makefile grep: fix LINKS in Makefile 2021-01-18 11:22:48 +01:00
Makefile.depend
Makefile.depend.options
queue.c grep: replace the internal queue with a ring buffer 2020-12-09 05:27:45 +00:00
util.c grep: fix -A handling in conjunction with -m match limitation 2021-02-08 12:41:22 -06:00
zgrep.1
zgrep.sh