The *_command functions in librados and libcephfs document the use
of specific free functions for data allocated. These functions are
currently just wrappers around C's free() function. However, to be
more strictly compliant this change adds a free-function callback
to the CommandOutput type and the specific free functions are now
used outside the unit tests.
Signed-off-by: John Mulligan <jmulligan@redhat.com>
Now we have sufficient boilerplate in our code for interacting with
various types and ceph calls with similar needs we establish a new
internal package, "cutil" (C utilities).
Note that many of the return types are wrapped. This is due to the
limits placed on us by cgo. Despite the irritating limitations Go
places on "exporting" C types it still ought to help in the long run for
patterns that are very common or patterns that are subtle and we want to
write specific tests for.
Signed-off-by: John Mulligan <jmulligan@redhat.com>
Our first operation is generating sizes for various caller-allocated
buffers. The WithSizes function "suggests" sizes to an anonymous
function that takes a size as an argument and returns a hint how
sucessful the attempt was. If required the same function is called
again with a larger size. Errors and other results of that anonymous
function are "communicated" with variables of the surrounding scope
in wich the function is defined.
Signed-off-by: John Mulligan <jmulligan@redhat.com>
Signed-off-by: Sven Anderson <sven@redhat.com>
Moving the errutil pkg to "internal/errutil" makes errutil private-like
and accessible to only other go-ceph packages. The functions it provided
were always meant to be used only by go-ceph, this just makes it more
official. This is a breaking change but it was only available to
outside users for 1 release and it is somewhat doubtful users outside
of go-ceph would have reached for these functions.
Signed-off-by: John Mulligan <jmulligan@redhat.com>
As per the Go Wiki page on cgo [1] passing callback with data between C
and Go is non-trivial due to the pointer passing rules [2]. This change
creates a new helper type, based on the examples on the wiki, that uses
opaque indexes to exchange between C and Go.
For now, this type is simple as we're only going to have a few callbacks
initially but this could easily be improved and made more general in the
future as needed. Because we anticipate having to use this type in all
of our core packages (rados and cephfs as well as rbd) we are creating
the type in an "internal" package so that we don't treat the new type
as public despite the capitalized method names.
[1]: https://github.com/golang/go/wiki/cgo
[2]: https://golang.org/cmd/cgo/#hdr-Passing_pointers
Signed-off-by: John Mulligan <jmulligan@redhat.com>
