Don't bother using checked type assertion for stat since we are
guarded by specific build configuration, we should know the
correct type, and if not, panicing is fine.
Despite syscall being deprecated a decade ago, we still need it
for FileInfo and sys/windows still calls it as well.
- Improve error handling of file flags and xattrs. You now get warnings
- file flags on *BSD/Darwin use a mask and combine with the user/superuser
mask to prevent spurious warnings. The mask is not yet implemented as
a preference
- error handling/report for reading special files
- bump to go 1.20 for errors.Join
- the xattr handling of namespaces is different on BSD with the
xattr package, the user namespace is implicit
- Don't backup/exclude files with flag nodump on BSD/Darwin
Fix Linux, Darwin, and other BSD (untested) to allow proper
handling of xattrs with symlinks. On Linux we cannot use the f*
syscalls for symlinks because symlinks cannot be opened.
File flags must be handled differently on darwin and other BSD due
to the lack of the LCHFLAGS syscall on darwin, and the fact that it
is emulated in libc. However, we do have O_SYMLINK on darwin.
Special files are device nodes and named pipes. The necessity of the
former is clear, the latter is debatable.
In order to preserve backward compatibility, the device number is
encoded in the StartChunk/StartOffset fields of the entry.
Basic support for BSD and Darwin style chflags (stat flags). Applies
these flags at the end of file restore.
Supports linux style ioctl_iflags(2) in a 2 step process. Flags that
need to be applied prior to writes such as compress and especially no-COW
are applied immediately upon file open.
The flags format is backwards compatible. An attribute starting with a
null byte is used to store flags in the entry attributes table. With
an old version of duplicacy the restore of this attribute should silently
fail (effectively be ignored).
Fixes xattr restore to use O_NOFOLLOW so attributes are applied to symlink.
TODO: Tests, possible option to switch off mutable/append prior to
restore of existing file similar to rsync. Does not apply attributes
or flags to the top most directory.
The exclude by attribute function is broken on non-Darwin POSIX: linux and freebsd.
This is because those xattrs must be prefixed by a legal namespace. The old xattr
library implicitly appended the user namespace to the xattr, but the current
official go pkg does not (which is just as well).
Also fix the test to remove the discordant old xattr dependency and provide
test cases for both darwin and non-darwin POSIX.
