install: Expect EINTR while copying

[des]

Summary

Both copy_file_range() and read() / write() in our fallback loop can be
interrupted before copying anything at all, in which case it returns -1
and sets errno to EINTR. If that happens, we should retry, not fail.

While here, drop the size argument from copy() (we always want to copy
the entire file anyway) and add a test case that exercises the metalog
and digest functionality.

MFC after: 1 week
PR: 293028

[des]

Fix fallback too. This is an excellent argument for creating
something like Apple's libcopyfile...

[des]

fix digest

[des]

range

[kevans]

usr.bin/xinstall/tests/install_test.sh

527

A filename with a space that needs encoded would maybe be useful here, to demonstrate that it's properly escaping

[des]

usr.bin/xinstall/tests/install_test.sh

527

The point of this test is to exercise the digest functionality, which I accidentally broke in an earlier version of this patch. What you describe belongs in a more general test of the metalog functionality, which is not my goal here.

[kevans]

usr.bin/xinstall/tests/install_test.sh

527

That is the impression you give by writing

test case that exercises the metalog and digest functionality.

I'm not asking for exhaustive metalog tests, just one specific bit that's easy to screw up and super easy to test while you're already here.

[des]

add metalog test

[kevans]

Thanks!