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19 * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
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29 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
43 #define NBDKIT_API_VERSION 2
44 #include <nbdkit-plugin.h>
46 #include "byte-swapping.h"
49 /* The size of disk in bytes (initialized by size=<SIZE> parameter). */
50 static int64_t size
= 0;
53 pattern_config (const char *key
, const char *value
)
57 if (strcmp (key
, "size") == 0) {
58 r
= nbdkit_parse_size (value
);
64 nbdkit_error ("unknown parameter '%s'", key
);
71 #define pattern_config_help \
72 "size=<SIZE> (required) Size of the backing disk"
74 #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL
76 /* Create the per-connection handle. */
78 pattern_open (int readonly
)
80 return NBDKIT_HANDLE_NOT_NEEDED
;
83 /* Get the disk size. */
85 pattern_get_size (void *handle
)
90 /* Serves the same data over multiple connections. */
92 pattern_can_multi_conn (void *handle
)
99 pattern_can_cache (void *handle
)
101 /* Everything is already in memory, returning this without
102 * implementing .cache lets nbdkit do the correct no-op.
104 return NBDKIT_CACHE_NATIVE
;
109 pattern_pread (void *handle
, void *buf
, uint32_t count
, uint64_t offset
,
118 d
= htobe64 (offset
& ~7);
120 n
= MIN (count
, 8-o
);
121 memcpy (b
, (char *)&d
+ o
, n
);
130 static struct nbdkit_plugin plugin
= {
132 .version
= PACKAGE_VERSION
,
133 .config
= pattern_config
,
134 .config_help
= pattern_config_help
,
135 .magic_config_key
= "size",
136 .open
= pattern_open
,
137 .get_size
= pattern_get_size
,
138 .can_multi_conn
= pattern_can_multi_conn
,
139 .can_cache
= pattern_can_cache
,
140 .pread
= pattern_pread
,
141 /* In this plugin, errno is preserved properly along error return
142 * paths from failed system calls.
144 .errno_is_preserved
= 1,
147 NBDKIT_REGISTER_PLUGIN (plugin
)