Standard is at http://pubs.opengroup.org/onlinepubs/9699919799/utilities/grep.html

Fairly straightforward changes, description as follows:

fastgrep.c:
Handle ^$ pattern correctly. Simple test is `echo | grep "^$"` - it
should match the single line.

grep.c:
As described in the standard, "The pattern_list's value shall consist
of one or more patterns separated by <newline> characters"

util.c:
For the purposes of the standard, inaccessible = nonexistent.

Also don't match the empty end of the line. Simple test for that:
`echo abc#def | grep "^[A-Za-z0-9]*$"` should not match anything.

Fix: Patch attached.

Patch attached with submission follows:
How-To-Repeat: See description for test cases.