Re: [Libguestfs] [PATCH libnbd] copy: Refactor ‘struct rw’.

Make this a (fairly) abstract structure. At least hide the subtype fields from the main program. This change is pure refactoring and doesn’t change the semantics. --- copy/file-ops.c | 164 +++++++++++++++++-- copy/main.c | 315 ++++++++---------------------------- copy/multi-thread-copying.c | 104 ++++++------ copy/nbd-ops.c | 248 +++++++++++++++++++++++++--- copy/nbdcopy.h | 53 +++--- copy/null-ops.c | 50 +++++- copy/pipe-ops.c | 64 +++++++- copy/synch-copying.c | 30 ++-- 8 files changed, 649 insertions(+), 379 deletions(-)

+++ b/copy/nbdcopy.h @@ -36,8 +36,6 @@ */ #define THREAD_WORK_SIZE (128 * 1024 * 1024) -DEFINE_VECTOR_TYPE (handles, struct nbd_handle *) - /* Abstracts the input (src) and output (dst) parameters on the * command line. */ @@ -45,21 +43,20 @@ struct rw { struct rw_ops *ops; /* Operations. */ const char *name; /* Printable name, for error messages etc. */ int64_t size; /* May be -1 for streams. */ - union { - struct { /* For files and pipes. */ - int fd; - struct stat stat; - bool seek_hole_supported; - int sector_size; - } local; - struct { - handles handles; /* For NBD, one handle per connection. */ - bool can_trim, can_zero; /* Cached nbd_can_trim, nbd_can_zero. */ - } nbd; - } u; + /* Followed by private data for the particular subtype. */ }; -extern struct rw src, dst; +extern struct rw *src, *dst; + +/* Create subtypes. */ +extern struct rw *file_create (const char *name, + const struct stat *stat, int fd); +extern struct rw *nbd_rw_create_uri (const char *name, + const char *uri, bool writing); +extern struct rw *nbd_rw_create_subprocess (const char **argv, size_t argc, + bool writing); +extern struct rw *null_create (const char *name); +extern struct rw *pipe_create (const char *name, int fd); /* Underlying data buffers. */ struct buffer { @@ -117,6 +114,28 @@ struct rw_ops { /* Close the connection and free up associated resources. */ void (*close) (struct rw *rw); + /* Return true if this is a read-only connection. */ + bool (*is_read_only) (struct rw *rw); + + /* For source only, does it support reading extents? */ + bool (*can_extents) (struct rw *rw); + + /* Return true if the connection can do multi-conn. This is true + * for files, false for streams, and passed through for NBD. + */ + bool (*can_multi_conn) (struct rw *rw); + + /* For multi-conn capable backends, before copying we must call this + * to begin multi-conn. For NBD this means opening the additional + * connections. + */ + void (*start_multi_conn) (struct rw *rw); + + /* Truncate, only called on output files. This callback can be NULL + * for types that don't support this. + */ + void (*truncate) (struct rw *rw, int64_t size); + /* Flush pending writes to permanent storage. */ void (*flush) (struct rw *rw);