https://bugzilla.redhat.com/show_bug.cgi?id=1656255

If virSecretGetSecretString is using by secretLookupByUUID,
then it's possible the found sec->usageType doesn't match the
desired @secretUsageType. If this occurs for the encrypted
volume creation processing and a subsequent pool refresh is
executed, then the secret used to create the volume will not
be found by the storageBackendLoadDefaultSecrets which expects
to find secrets by VIR_SECRET_USAGE_TYPE_VOLUME.

Add a check to virSecretGetSecretString to avoid the possibility
along with an error indicating the incorrect matched types.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>
ACKed-by: NMichal Privoznik <mprivozn@redhat.com>

Move the enum into a new src/util/virsecret.h, rename it to be
virSecretLookupType. Add a src/util/virsecret.h in order to perform
a couple of simple operations on the secret XML and virSecretLookupTypeDef
for clearing and copying.

This includes quite a bit of collateral damage, but the goal is to remove
the "virStorage*" and replace with the virSecretLookupType so that it's
easier to to add new lookups that aren't necessarily storage pool related.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

Rather than returning a "char *" indicating perhaps some sized set of
characters that is NUL terminated, alter the function to return 0 or -1
for success/failure and add two parameters to handle returning the
buffer and it's size.

The function no longer encodes the returned secret, rather it returns
the unencoded secret forcing callers to make the necessary adjustments.

Alter the callers to handle the adjusted model.
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

Call the internal driver callbacks rather than the public APIs to avoid
calling unnecessarily the error dispatching code and don't overwrite
the error messages provided by the APIs. They are good enough to
describe which secret is missing either by UUID or the usage (basically
name).

Commit id 'fb2bd208' essentially copied the qemuGetSecretString
creating an libxlGetSecretString.  Rather than have multiple copies
of the same code, create src/secret/secret_util.{c,h} files and
place the common function in there.

Modify the the build in order to build the module as a library
which is then pulled in by both the qemu and libxl drivers for
usage from both qemu_command.c and libxl_conf.c