Hia Dominic, I've looked into this a bit. I think I may now be less confused. :-) On Wed, 2009-01-21 at 18:01 +0000, Dominic Steinitz wrote:
We use System.Directory.copyFile which copies the permissions from the original file to the destination file. Could you confirm that this is working correctly. Are the permissions of the source and destination files exactly the same? Was the source file created read-only?
haskell_packages is empty to start with and the package gets built successfully. Attributes are copied over successfully. The actual source files *are* read only as they are kept in our source control system which marks them this way for unchecked out files. Built files are read / write.
Ok, that's fine. It's as we expect.
ls -ltr haskell_packages\doc\zlib-0.5.0.0 total 2 -r--r--r-- 1 user group 1327 Jan 21 11:37 LICENSE
Ah! Is that the only file that is read-only? That makes sense since it's an original source file from your read-only source control system. The System.Directory.copyFile function does not copy permissions (though it does try to) but it does (unhelpfully) copy the read-only attribute.
When I rebuild the package *without* having cleaned out haskell_packages then I get the access error. I think this is because cabal (copyFile) doesn't want to overwrite a read only file even though the directory permissions should allow it to do so.
Yes. The windows MoveFile function does not let us move a file over a file that has the read-only attribute. It's an annoying interaction between the semantics of old DOS/FAT read-only attribute and new windows file permissions (ACLs). The solution I think, is never to copy the read-only attribute when installing files. It's thoroughly unhelpful. I've got a patch to do this which I shall push to Cabal HEAD shortly. If you have a moment to help me test that it would be much appreciated.
This looks like: http://hackage.haskell.org/trac/hackage/ticket/454
But for every file not just .exe files. For .exe files Cabal does the permission copying itself. I do not understand why it just started occurring, since ghc-6.8 and 6.10 seem to have the same code for copyFile and copyPermissions.
I don't seem to have the problem for binaries (because cabal builds them afresh with read / write permission) so I don't know if it's related or not (but it seems unlikely).
I think you're right that it's unrelated. Your problem is caused by Cabal copying the read-only attribute where as that ticket turns out to be more related to permissions (ACLs) and users and inherited permissions etc. Duncan