On 11/8/2020 9:40 AM, Michael Soegtrop wrote:
Why shouldn't I be able to remove symlinks with rm -rf from within a cygwin? As
far as I understand the standard behavior of "rm" is to remove the symlink and
not its target. What I do when I remove a cygwin installation in our CI is an
"rm -rf" from a different cygwin installation. As I said in most cases this
works but rarely it doesn't.
[...]
I understand that the contents / path of the symlink is as expected, so I am
looking out for other oddities which could explain this behavior.
I've seen this behavior only in the following situation. Suppose you create a
symlink in one Cygwin installation that uses WSL symlinks. Then you try to
delete it from a different Cygwin installation with version < 3.1.5 (which is
when WSL symlinks were first supported). This will fail, because the older
Cygwin installation will see a reparse point of a type that it doesn't recognize.
From what you say, it sounds like this doesn't apply to your situation, so I'm
at a loss to explain it.
Do you get any error message when you're unable to delete a symlink in one
Cygwin installation from another? If not, you could try running 'rm <cygwin
root>/usr/share/fonts/microsoft/wingding.ttf' under strace to see if that give
you any clues. You could also try 'file', 'ls -l', 'stat', etc., to see if
Cygwin is correctly recognizing the file as a symlink.
For example, I have a Cygwin installation in C:\cygwin64test. From a different
Cygwin installation in which C: is mounted on /c, I see the following:
$ file /c/cygwin64test/usr/share/fonts/microsoft/wingding.ttf
/c/cygwin64test/usr/share/fonts/microsoft/wingding.ttf: symbolic link to
/c/Windows/Fonts/wingding.ttf
Now I remove that symlink under strace:
$ strace -o strace.out rm /c/cygwin64test/usr/share/fonts/microsoft/wingding.ttf
In the file strace.out I see
57 26112 [main] rm 39456 symlink_info::check: 0x0 = NtCreateFile
(\??\C:\cygwin64test\usr\share\fonts\microsoft\wingding.ttf)
100 26212 [main] rm 39456 symlink_info::check: 29 =
symlink.check(C:\cygwin64test\usr\share\fonts\microsoft\wingding.ttf,
0xFFFFB680) (mount_flags 0x4008, path_flags 0x10)
26 26238 [main] rm 39456 path_conv::check:
this->path(C:\cygwin64test\usr\share\fonts\microsoft\wingding.ttf), has_acls(1)
25 26263 [main] rm 39456 _unlink_nt: Trying to delete
\??\C:\cygwin64test\usr\share\fonts\microsoft\wingding.ttf, isdir = 0
218 26481 [main] rm 39456 _unlink_nt:
\??\C:\cygwin64test\usr\share\fonts\microsoft\wingding.ttf, return status = 0x0
33 26514 [main] rm 39456 unlink: 0 =
unlink(/c/cygwin64test/usr/share/fonts/microsoft/wingding.ttf)
In your case I would expect to see some errors reported when you are unable to
remove the symlink.
Ken
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