At 08:02 AM 6/22/2003, John Maddock wrote:
>I'm having a problem with the filesystem lib and read only files -
>basically
>if I copy a read only file then the result is read only, fair enough.
>However if I then try and overwrite that file with another file copy it
>throws because of the read only status of the target file, still fair
>enough. So then I try and remove the target file with remove first, but
>that throws as well because the file "not accessible" i.e. read only! So
-
>how can I get rid of a read only file? At present it seems to be
>impossible?
Yes, at the moment it is impossible with the filesystem library.
[Warning: half-baked ideas follows. I don't even know if it is spelled
writeable or writable.]
If we can figure out portable behavior that will work on POSIX and Windows,
and is likely safe if not useful on other operating systems, then perhaps
we should add something to like:
bool is_writeable( const path & );
On Windows, the return would reflect the state of the read-only attribute
bit.
On POSIX, the return would reflect the Write permission bit for the most
restrictive user class which applies.
On O/S's which have no concept which usefully maps into is_writeable,
return true.
Note that a true return from is_writeable() does not guarantee that a file
or directory can actually be written to by the program.
void set_writeable( const path &, bool value = true );
On Windows, would set the read-only attribute bit accordingly. May throw.
On POSIX, would set the write permission bit for the most restrictive user
class which applies. May throw.
On O/S's which have no concept of is_writeable, has no effect. Does not
throw.
Comments?
--Beman
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