Symlinks on read-only FS

[Deomid Ryabkov]

Perry Hutchison wrote:

> So the sort of write access being validated here would be writing to
> the symlink itself (i.e. the definition)?

symlinks are dereferenced during name lookup and are not affected by
the write mount options of the filesystems they reside on.
you can open a file for write by accessing a symlink pointing to it,
even though the symlink itself may reside on a read-only filesystem.

and you can disregard what i said in my previous post: there's no interface
to change the symlink after it was created.

actually, i'm not sure there is a real-world case in which this code
would be invoked with VLNK.
checking write permissions on a symlink? access(2)/eaccess(2) dereference symlinks.
but if, for whatever reason, someone calls VOP_ACCESS on read-only
UFS filesystem, checking if writing to symlink itself is ok, it will be denied.
which makes sense.

-- 
Deomid Ryabkov aka Rojer
myself at rojer.pp.ru
rojer at sysadmins.ru
ICQ: 8025844
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