db/hash.c: Allow O_WRONLY in dbm_open

[bnovkov]

Summary

The dbm(3) manpage explicitly states that O_WRONLY is not allowed in
dbm_open, but a more recent comment in __hash_open suggests otherwise.
Furthermore, POSIX.1 allows O_WRONLY in dbm_open and states
that the underlying file must be opened for both reading and writing.

Fix this by correcting the O_WRONLY check and moving it further into
the function to make sure that the original flags are stored in hashp.

Sponsored by: Klara, Inc.

[markj]

lib/libc/db/hash/hash.c

182

Should this be checking flags instead?

lib/libc/db/man/dbm.3

104

The modified code is also used by dbopen(3), which has the same comment in its man page.

[bnovkov]

Address @markj 's comments.

lib/libc/db/hash/hash.c

182

hm, looks like it should.
The comment next to save_file member implies so since it refers to the underlying database file:

int             save_file;      /* Indicates whether we need to flush
                                         * file at
                                         * exit */

I've changed the check to use flags.

[markj]

lib/libc/db/hash/hash.c

517

It looks like this function should have an explicit check for a readable handle, just like hash_put() below checks for a writeable handle.

[bnovkov]

Add O_WRONLY check in hash_get and add corresponding tests.

[bnovkov]

lib/libc/db/hash/hash.c

517

done, thanks!

[markj]

lib/libc/tests/db/dbm_open_test.c

31–41

I think you shouldn't need this? ATF tests should always be run in a sandbox dir.

lib/libc/tests/db/dbm_perm_test.c

19

29

Or just assert that the unlink() above succeeds?

[bnovkov]

lib/libc/tests/db/dbm_open_test.c

31–41

ah right, will fix while pushing, thanks