s3-vfs: add copy_chunk vfs hooks

copy_chunk copies n bytes from a source file at a specific offset to a
destination file at a given offset. This interface will be used in
handling smb2 FSCTL_SRV_COPYCHUNK ioctl requests.

Use a pread/pwrite loop in vfs_default, so that requests referring to
the same src and dest file are possible.

Provide send and receive hooks for copy chunk VFS interface, allowing
asynchronous behaviour.

Check whether the request source offset + length exceeds the current
size. Return STATUS_INVALID_VIEW_SIZE under such a condition, matching
Windows server behaviour.

Reviewed by: Jeremy Allison <jra@samba.org>

2 files changed, 117 insertions, 0 deletions

diff --git a/examples/VFS/skel_opaque.c b/examples/VFS/skel_opaque.c
index 6948d6452e4..53c64cafb88 100644
--- a/examples/VFS/skel_opaque.c
+++ b/examples/VFS/skel_opaque.c
@@ -22,6 +22,7 @@
  */
 
 #include "../source3/include/includes.h"
+#include "lib/util/tevent_ntstatus.h"
 
 /* PLEASE,PLEASE READ THE VFS MODULES CHAPTER OF THE 
    SAMBA DEVELOPERS GUIDE!!!!!!
@@ -488,6 +489,45 @@ static struct file_id skel_file_id_create(vfs_handle_struct *handle,
 	return id;
 }
 
+struct skel_cc_state {
+	uint64_t unused;
+};
+static struct tevent_req *skel_copy_chunk_send(struct vfs_handle_struct *handle,
+					       TALLOC_CTX *mem_ctx,
+					       struct tevent_context *ev,
+					       struct files_struct *src_fsp,
+					       off_t src_off,
+					       struct files_struct *dest_fsp,
+					       off_t dest_off,
+					       off_t num)
+{
+	struct tevent_req *req;
+	struct skel_cc_state *cc_state;
+
+	req = tevent_req_create(mem_ctx, &cc_state, struct skel_cc_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	tevent_req_nterror(req, NT_STATUS_NOT_IMPLEMENTED);
+	return tevent_req_post(req, ev);
+}
+
+static NTSTATUS skel_copy_chunk_recv(struct vfs_handle_struct *handle,
+				     struct tevent_req *req,
+				     off_t *copied)
+{
+	NTSTATUS status;
+
+	if (tevent_req_is_nterror(req, &status)) {
+		tevent_req_received(req);
+		return status;
+	}
+	tevent_req_received(req);
+
+	return NT_STATUS_OK;
+}
+
 static NTSTATUS skel_streaminfo(struct vfs_handle_struct *handle,
 				struct files_struct *fsp,
 				const char *fname,
@@ -825,6 +865,8 @@ struct vfs_fn_pointers skel_opaque_fns = {
 	.notify_watch_fn = skel_notify_watch,
 	.chflags_fn = skel_chflags,
 	.file_id_create_fn = skel_file_id_create,
+	.copy_chunk_send_fn = skel_copy_chunk_send,
+	.copy_chunk_recv_fn = skel_copy_chunk_recv,
 
 	.streaminfo_fn = skel_streaminfo,
 	.get_real_filename_fn = skel_get_real_filename,
diff --git a/examples/VFS/skel_transparent.c b/examples/VFS/skel_transparent.c
index 02e818424d2..99feadec600 100644
--- a/examples/VFS/skel_transparent.c
+++ b/examples/VFS/skel_transparent.c
@@ -23,6 +23,7 @@
 
 #include "../source3/include/includes.h"
 #include "lib/util/tevent_unix.h"
+#include "lib/util/tevent_ntstatus.h"
 
 /* PLEASE,PLEASE READ THE VFS MODULES CHAPTER OF THE 
    SAMBA DEVELOPERS GUIDE!!!!!!
@@ -572,6 +573,78 @@ static struct file_id skel_file_id_create(vfs_handle_struct *handle,
 	return SMB_VFS_NEXT_FILE_ID_CREATE(handle, sbuf);
 }
 
+struct skel_cc_state {
+	struct vfs_handle_struct *handle;
+	off_t copied;
+};
+static void skel_copy_chunk_done(struct tevent_req *subreq);
+
+static struct tevent_req *skel_copy_chunk_send(struct vfs_handle_struct *handle,
+					       TALLOC_CTX *mem_ctx,
+					       struct tevent_context *ev,
+					       struct files_struct *src_fsp,
+					       off_t src_off,
+					       struct files_struct *dest_fsp,
+					       off_t dest_off,
+					       off_t num)
+{
+	struct tevent_req *req;
+	struct tevent_req *subreq;
+	struct skel_cc_state *cc_state;
+
+	req = tevent_req_create(mem_ctx, &cc_state, struct skel_cc_state);
+	if (req == NULL) {
+		return NULL;
+	}
+
+	cc_state->handle = handle;
+	subreq = SMB_VFS_NEXT_COPY_CHUNK_SEND(handle, cc_state, ev,
+					      src_fsp, src_off,
+					      dest_fsp, dest_off, num);
+	if (tevent_req_nomem(subreq, req)) {
+		return tevent_req_post(req, ev);
+	}
+
+	tevent_req_set_callback(subreq, skel_copy_chunk_done, req);
+	return req;
+}
+
+static void skel_copy_chunk_done(struct tevent_req *subreq)
+{
+	struct tevent_req *req = tevent_req_callback_data(
+		subreq, struct tevent_req);
+	struct skel_cc_state *cc_state
+			= tevent_req_data(req, struct skel_cc_state);
+	NTSTATUS status;
+
+	status = SMB_VFS_NEXT_COPY_CHUNK_RECV(cc_state->handle,
+					      subreq,
+					      &cc_state->copied);
+	TALLOC_FREE(subreq);
+	if (tevent_req_nterror(req, status)) {
+		return;
+	}
+	tevent_req_done(req);
+}
+
+static NTSTATUS skel_copy_chunk_recv(struct vfs_handle_struct *handle,
+				     struct tevent_req *req,
+				     off_t *copied)
+{
+	struct skel_cc_state *cc_state
+			= tevent_req_data(req, struct skel_cc_state);
+	NTSTATUS status;
+
+	*copied = cc_state->copied;
+	if (tevent_req_is_nterror(req, &status)) {
+		tevent_req_received(req);
+		return status;
+	}
+
+	tevent_req_received(req);
+	return NT_STATUS_OK;
+}
+
 static NTSTATUS skel_streaminfo(struct vfs_handle_struct *handle,
 				struct files_struct *fsp,
 				const char *fname,
@@ -898,6 +971,8 @@ struct vfs_fn_pointers skel_transparent_fns = {
 	.notify_watch_fn = skel_notify_watch,
 	.chflags_fn = skel_chflags,
 	.file_id_create_fn = skel_file_id_create,
+	.copy_chunk_send_fn = skel_copy_chunk_send,
+	.copy_chunk_recv_fn = skel_copy_chunk_recv,
 
 	.streaminfo_fn = skel_streaminfo,
 	.get_real_filename_fn = skel_get_real_filename,