[Libguestfs] [nbdkit PATCH] filters: Remove most next_* wrappers
Eric Blake
eblake at redhat.com
Wed Feb 12 15:38:29 UTC 2020
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 at redhat.com>
---
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
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