pkill: use an ARG_MAX size buffer for argument matching

[kevans]

Summary

Right now pkill/pgrep cut off at _POSIX2_LINE_MAX (2048), but argument
strings can be much larger (ARG_MAX is 256K/512K). Stop arbitrarily
cutting the search off at 2K, rather than documenting the limit.

Sponsored by: Klara, Inc.

[allanjude]

Reviewed by: allanjude

[des]

bin/pkill/pkill.c

393

The first half of this is meaningless since we grow the buffer.

403

Is there a possibility that this is still less than jsz + arglen? Perhaps use roundup(jsz + arglen, DFLT_BUF_SIZE) instead?

bin/pkill/tests/pgrep-f_test.sh

24

s/one/once/

[des]

bin/pkill/pkill.c

66

Not needed.

153

408

[des]

bin/pkill/pkill.c

403

btw if you do this you can also skip the initiall calloc() and just initialize buf to NULL and bufsz to 0, drop MAX_BUF_INCREMENT and rename DFLT_BUF_SIZE to BUF_INCREMENT; also, the comment immediately above this becomes moot.

[kevans]

bin/pkill/pkill.c

403

I'm toying with the idea of just allocating an ARG_MAX * 2 buffer if we're doing arg matching and dropping this realloc business; should be a 1MB buffer on FreeBSD and easily handle everything.

Can't quite initialize buf to NULL because it's reused elsewhere earlier in the code at the moment for error strings

[des]

bin/pkill/pkill.c

403

That works too but in that case I would use malloc(), not calloc().

[kevans]

Switch to a fixed ARG_MAX * 2 buffer instead of complicating it with realloc()

[kevans]

s/1/STATUS_ERROR/ per review comment