Added basic support for FreeBSD.

Freebsd-support: Change bash shebang to use /usr/bin/env

Freebsd-support: Fix go vet "undefined" fixes when running make ci

freebsd: stub xattr functions

/proc/PID/fd does not exist on freebsd.

freebsd-support: modify FchmodatNofollow for FreeBSD

FreeBSD supports the Fchmodat system call, with the AT_SYMLINK_NOFOLLOW
flag. FchmodatNofollow has been modified to use this system call and
flag.

freebsd-support: PR changes and fixes

* Functions in fusefrontend_reverse/node_xattr_freebsd.go have been
  stubbed for now.

* asuser_freebsd.go updated to only run f() when context is nil;
  otherwise log a warning and return an error.

* emulate.go build flags updated, and FreeBSD specific version added.

* sys_freebsd.go bug in Renameat2 with RENAME_EXCHANGE flag fixed.
  FreeBSD does not support atomic file swapping, so this flag now
  returns an error.

* unix2syscall and atime is identical between FreeBSD and Darwin,
  updated filenames so Go will build the file for FreeBSD and Mac OS.

freebsd-support: Addressed more PR comments and fixed build tags

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/matrix/atime_darwin+freebsd.go b/tests/matrix/atime_darwin+freebsd.go
new file mode 100644
index 0000000..43db0d5
--- /dev/null
+++ b/tests/matrix/atime_darwin+freebsd.go
@@ -0,0 +1,11 @@
+//go:build darwin || freebsd
+
+package matrix
+
+import (
+	"syscall"
+)
+
+func extractAtimeMtime(st syscall.Stat_t) [2]syscall.Timespec {
+	return [2]syscall.Timespec{st.Atimespec, st.Mtimespec}
+}