[Libguestfs] [nbdkit PATCH] filters: Remove most next_* wrappers

With our recent cleanups to nxdata, the only remaining difference between functions like backend_open() and next_open() was the signature (one used void*, the other struct backend *); the API is compatible. All of our filters are in-tree, and we don't promise API/ABI stability, but it is still a lot of files to touch, so the simplest solution to avoid the redundant hop through wrapper functions is to change our header to compile with a typedef, which is either 'struct backend *' for internal code or 'void *' for filters. With this in place, we can now delete most of the next_* wrappers, by pointing to corresponding backend_* functions instead; the few exceptions are .config and .config_complete (the public API returns an integer, but the backend code exits on failure and thus returns void), and .preconnect (we don't have a backend_preconnect function). Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- The alternative to the #ifdef'd typedef is to touch all of the filters/*.c files to change 'void *nxdata' to 'struct backend *nxdata'. include/nbdkit-filter.h | 119 ++++++++++++----------- server/filters.c | 208 +++++----------------------------------- server/internal.h | 3 +- 3 files changed, 89 insertions(+), 241 deletions(-) diff --git a/include/nbdkit-filter.h b/include/nbdkit-filter.h index f7705d67..50b3d55a 100644 --- a/include/nbdkit-filter.h +++ b/include/nbdkit-filter.h @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013-2019 Red Hat Inc. + * Copyright (C) 2013-2020 Red Hat Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are @@ -49,47 +49,56 @@ extern "C" { #define NBDKIT_ZERO_EMULATE 1 #define NBDKIT_ZERO_NATIVE 2 +#ifdef NBDKIT_INTERNAL +/* Opaque type encapsulating all information needed for calling into + * the next filter or plugin. + */ +typedef struct backend backend; +#else +typedef void backend; +#endif + /* Next ops. */ -typedef int nbdkit_next_config (void *nxdata, +typedef int nbdkit_next_config (backend *nxdata, const char *key, const char *value); -typedef int nbdkit_next_config_complete (void *nxdata); -typedef int nbdkit_next_preconnect (void *nxdata, int readonly); -typedef int nbdkit_next_open (void *nxdata, int readonly); +typedef int nbdkit_next_config_complete (backend *nxdata); +typedef int nbdkit_next_preconnect (backend *nxdata, int readonly); +typedef int nbdkit_next_open (backend *nxdata, int readonly); struct nbdkit_next_ops { /* Performs close + open on the underlying chain. * Used by the retry filter. */ - int (*reopen) (void *nxdata, int readonly); + int (*reopen) (backend *nxdata, int readonly); /* The rest of the next ops are the same as normal plugin operations. */ - int64_t (*get_size) (void *nxdata); - - int (*can_write) (void *nxdata); - int (*can_flush) (void *nxdata); - int (*is_rotational) (void *nxdata); - int (*can_trim) (void *nxdata); - int (*can_zero) (void *nxdata); - int (*can_fast_zero) (void *nxdata); - int (*can_extents) (void *nxdata); - int (*can_fua) (void *nxdata); - int (*can_multi_conn) (void *nxdata); - int (*can_cache) (void *nxdata); - - int (*pread) (void *nxdata, void *buf, uint32_t count, uint64_t offset, + int64_t (*get_size) (backend *nxdata); + + int (*can_write) (backend *nxdata); + int (*can_flush) (backend *nxdata); + int (*is_rotational) (backend *nxdata); + int (*can_trim) (backend *nxdata); + int (*can_zero) (backend *nxdata); + int (*can_fast_zero) (backend *nxdata); + int (*can_extents) (backend *nxdata); + int (*can_fua) (backend *nxdata); + int (*can_multi_conn) (backend *nxdata); + int (*can_cache) (backend *nxdata); + + int (*pread) (backend *nxdata, void *buf, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*pwrite) (void *nxdata, + int (*pwrite) (backend *nxdata, const void *buf, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*flush) (void *nxdata, uint32_t flags, int *err); - int (*trim) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - int *err); - int (*zero) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - int *err); - int (*extents) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - struct nbdkit_extents *extents, int *err); - int (*cache) (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - int *err); + int (*flush) (backend *nxdata, uint32_t flags, int *err); + int (*trim) (backend *nxdata, uint32_t count, uint64_t offset, + uint32_t flags, int *err); + int (*zero) (backend *nxdata, uint32_t count, uint64_t offset, + uint32_t flags, int *err); + int (*extents) (backend *nxdata, uint32_t count, uint64_t offset, + uint32_t flags, struct nbdkit_extents *extents, int *err); + int (*cache) (backend *nxdata, uint32_t count, uint64_t offset, + uint32_t flags, int *err); }; /* Extent functions. */ @@ -127,66 +136,66 @@ struct nbdkit_filter { void (*load) (void); void (*unload) (void); - int (*config) (nbdkit_next_config *next, void *nxdata, + int (*config) (nbdkit_next_config *next, backend *nxdata, const char *key, const char *value); - int (*config_complete) (nbdkit_next_config_complete *next, void *nxdata); + int (*config_complete) (nbdkit_next_config_complete *next, backend *nxdata); const char *config_help; int (*thread_model) (void); - int (*preconnect) (nbdkit_next_preconnect *next, void *nxdata, int readonly); + int (*preconnect) (nbdkit_next_preconnect *next, backend *nxdata, + int readonly); - void * (*open) (nbdkit_next_open *next, void *nxdata, + void * (*open) (nbdkit_next_open *next, backend *nxdata, int readonly); void (*close) (void *handle); - int (*prepare) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*prepare) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, int readonly); - int (*finalize) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*finalize) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int64_t (*get_size) (struct nbdkit_next_ops *next_ops, void *nxdata, + int64_t (*get_size) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_write) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_write) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_flush) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_flush) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); int (*is_rotational) (struct nbdkit_next_ops *next_ops, - void *nxdata, - void *handle); - int (*can_trim) (struct nbdkit_next_ops *next_ops, void *nxdata, + backend *nxdata, void *handle); + int (*can_trim) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_zero) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_zero) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_fast_zero) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_fast_zero) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_extents) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_extents) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_fua) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_fua) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_multi_conn) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_multi_conn) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*can_cache) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*can_cache) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle); - int (*pread) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*pread) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, void *buf, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*pwrite) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*pwrite) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, const void *buf, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*flush) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*flush) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, uint32_t flags, int *err); - int (*trim) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*trim) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*zero) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*zero) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, uint32_t count, uint64_t offset, uint32_t flags, int *err); - int (*extents) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*extents) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, uint32_t count, uint64_t offset, uint32_t flags, struct nbdkit_extents *extents, int *err); - int (*cache) (struct nbdkit_next_ops *next_ops, void *nxdata, + int (*cache) (struct nbdkit_next_ops *next_ops, backend *nxdata, void *handle, uint32_t count, uint64_t offset, uint32_t flags, int *err); }; diff --git a/server/filters.c b/server/filters.c index 92b0ceb3..8985ebeb 100644 --- a/server/filters.c +++ b/server/filters.c @@ -127,9 +127,8 @@ filter_dump_fields (struct backend *b) } static int -next_config (void *nxdata, const char *key, const char *value) +next_config (struct backend *b, const char *key, const char *value) { - struct backend *b = nxdata; b->config (b, key, value); return 0; } @@ -151,9 +150,8 @@ filter_config (struct backend *b, const char *key, const char *value) } static int -next_config_complete (void *nxdata) +next_config_complete (struct backend *b) { - struct backend *b = nxdata; b->config_complete (b); return 0; } @@ -173,13 +171,6 @@ filter_config_complete (struct backend *b) b->next->config_complete (b->next); } -static int -next_preconnect (void *nxdata, int readonly) -{ - struct backend *b_next = nxdata; - return b_next->preconnect (b_next, readonly); -} - static int filter_preconnect (struct backend *b, int readonly) { @@ -188,7 +179,7 @@ filter_preconnect (struct backend *b, int readonly) debug ("%s: preconnect", b->name); if (f->filter.preconnect) - return f->filter.preconnect (next_preconnect, b->next, readonly); + return f->filter.preconnect (b->next->preconnect, b->next, readonly); else return b->next->preconnect (b->next, readonly); } @@ -202,14 +193,6 @@ plugin_magic_config_key (struct backend *b) return b->next->magic_config_key (b->next); } -static int -next_open (void *nxdata, int readonly) -{ - struct backend *b_next = nxdata; - - return backend_open (b_next, readonly); -} - static void * filter_open (struct backend *b, int readonly) { @@ -220,7 +203,7 @@ filter_open (struct backend *b, int readonly) * inner-to-outer ordering. */ if (f->filter.open) - handle = f->filter.open (next_open, b->next, readonly); + handle = f->filter.open (backend_open, b->next, readonly); else if (backend_open (b->next, readonly) == -1) handle = NULL; else @@ -237,171 +220,26 @@ filter_close (struct backend *b, void *handle) f->filter.close (handle); } -/* The next_functions structure contains pointers to backend - * functions. These are only needed for type safety (nxdata is void - * pointer, backend_* functions expect a struct backend * parameter). - * nxdata is a pointer to the next backend in the linked list. - */ - -static int -next_reopen (void *nxdata, int readonly) -{ - struct backend *b_next = nxdata; - return backend_reopen (b_next, readonly); -} - -static int64_t -next_get_size (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_get_size (b_next); -} - -static int -next_can_write (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_write (b_next); -} - -static int -next_can_flush (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_flush (b_next); -} - -static int -next_is_rotational (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_is_rotational (b_next); -} - -static int -next_can_trim (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_trim (b_next); -} - -static int -next_can_zero (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_zero (b_next); -} - -static int -next_can_fast_zero (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_fast_zero (b_next); -} - -static int -next_can_extents (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_extents (b_next); -} - -static int -next_can_fua (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_fua (b_next); -} - -static int -next_can_multi_conn (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_multi_conn (b_next); -} - -static int -next_can_cache (void *nxdata) -{ - struct backend *b_next = nxdata; - return backend_can_cache (b_next); -} - -static int -next_pread (void *nxdata, void *buf, uint32_t count, uint64_t offset, - uint32_t flags, int *err) -{ - struct backend *b_next = nxdata; - return backend_pread (b_next, buf, count, offset, flags, err); -} - -static int -next_pwrite (void *nxdata, const void *buf, uint32_t count, uint64_t offset, - uint32_t flags, int *err) -{ - struct backend *b_next = nxdata; - return backend_pwrite (b_next, buf, count, offset, flags, err); -} - -static int -next_flush (void *nxdata, uint32_t flags, int *err) -{ - struct backend *b_next = nxdata; - return backend_flush (b_next, flags, err); -} - -static int -next_trim (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - int *err) -{ - struct backend *b_next = nxdata; - return backend_trim (b_next, count, offset, flags, err); -} - -static int -next_zero (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - int *err) -{ - struct backend *b_next = nxdata; - return backend_zero (b_next, count, offset, flags, err); -} - -static int -next_extents (void *nxdata, uint32_t count, uint64_t offset, uint32_t flags, - struct nbdkit_extents *extents, int *err) -{ - struct backend *b_next = nxdata; - return backend_extents (b_next, count, offset, flags, extents, err); -} - -static int -next_cache (void *nxdata, uint32_t count, uint64_t offset, - uint32_t flags, int *err) -{ - struct backend *b_next = nxdata; - return backend_cache (b_next, count, offset, flags, err); -} - static struct nbdkit_next_ops next_ops = { - .reopen = next_reopen, - .get_size = next_get_size, - .can_write = next_can_write, - .can_flush = next_can_flush, - .is_rotational = next_is_rotational, - .can_trim = next_can_trim, - .can_zero = next_can_zero, - .can_fast_zero = next_can_fast_zero, - .can_extents = next_can_extents, - .can_fua = next_can_fua, - .can_multi_conn = next_can_multi_conn, - .can_cache = next_can_cache, - .pread = next_pread, - .pwrite = next_pwrite, - .flush = next_flush, - .trim = next_trim, - .zero = next_zero, - .extents = next_extents, - .cache = next_cache, + .reopen = backend_reopen, + .get_size = backend_get_size, + .can_write = backend_can_write, + .can_flush = backend_can_flush, + .is_rotational = backend_is_rotational, + .can_trim = backend_can_trim, + .can_zero = backend_can_zero, + .can_fast_zero = backend_can_fast_zero, + .can_extents = backend_can_extents, + .can_fua = backend_can_fua, + .can_multi_conn = backend_can_multi_conn, + .can_cache = backend_can_cache, + .pread = backend_pread, + .pwrite = backend_pwrite, + .flush = backend_flush, + .trim = backend_trim, + .zero = backend_zero, + .extents = backend_extents, + .cache = backend_cache, }; static int diff --git a/server/internal.h b/server/internal.h index 9d314bf8..eaec31ba 100644 --- a/server/internal.h +++ b/server/internal.h @@ -1,5 +1,5 @@ /* nbdkit - * Copyright (C) 2013-2019 Red Hat Inc. + * Copyright (C) 2013-2020 Red Hat Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are @@ -40,6 +40,7 @@ #include <pthread.h> #define NBDKIT_API_VERSION 2 +#define NBDKIT_INTERNAL #include "nbdkit-plugin.h" #include "nbdkit-filter.h" #include "cleanup.h" -- 2.24.1