Junio C Hamano <gitster@xxxxxxxxx> writes: > Adam Milazzo <Adam.Milazzo@xxxxxxxxxxxxx> writes: > >> Repro steps: >> 1. git init >> 2. mkdir d >> 3. touch d/a >> 4. chmod -w d >> 5. git clean -fd >> >> Actual result: >> Git doesn't remove anything, saying "warning: failed to remove d/a". >> >> Expected result: >> Git should remove the subdirectory 'd' along with its >> contents. Note that git can remove a read-only file (touch b; >> chmod -w b; git clean -f) with no problem. > > It is how UNIX-like filesystem works, isn't it? > > As long as a directory D is writable/executable, any regular file > inside it can be removed regardless of the perm-bits of the file. > > mkdir d > touch d/a > chmod -w d > rm d/a > > would not let you remove the file d/a from d/, exactly because you > cannot modify d/ (it is not writable). I realize that the above is probably a bit too terse for those who are not familiar with the UNIX/POSIX-like filesystems. A directory is a record of what files (and subdirectories) are in it. If you add a file to or remove a file from a directory, you are updating that record---so you need to be able to write to the directory. You do not have to be able to write (or even to read for that matter) to the file you are adding or removing to the directory, because adding or removing a file from a directory involves only updating the record kept in the directory about what files and subdirectories are in that directory (hence you need to be able to write to the directory---but perm bits on the files you are adding or removing do not play a role in this operation). A collorary is that modifying an existing file in a directory does not have to change what is recorded in the directory---what files are in the directory does not change. You only need to be able to write the file, so you can edit a file in a read-only directory. Note that some editors, however, implement an "edit" as "rename the original file as a backup, create a new copy of a file, and edit that new copy". With such an editor, you cannot "edit" a writable file in a read-only directory and the reason would by now be obvious to you once you understand the explanation above. Both renaming the original and creating the new copy would be updating what files are in the directory, requiring you to be able to write to the directory. Hope this helps.
