[Libguestfs] [nbdkit PATCH v2 1/5] server: Add exports list functions
Eric Blake
eblake at redhat.com
Thu Aug 6 02:25:18 UTC 2020
Add exports.c for manipulating an exports list, borrowing heavily from
similar code in managing an extents list. The new functions are
exposed through nbdkit-filter.h, because filters will eventually need
a way to grab the export list from a plugin, but actually wiring that
up will be in a later patch. For now, we enforce string length but
not strict UTF-8 content.
Signed-off-by: Eric Blake <eblake at redhat.com>
---
include/nbdkit-common.h | 4 +
include/nbdkit-filter.h | 12 +++
server/Makefile.am | 2 +
common/utils/cleanup.h | 3 +
server/exports.c | 149 ++++++++++++++++++++++++++++++++++
server/nbdkit.syms | 5 ++
common/utils/cleanup-nbdkit.c | 6 ++
7 files changed, 181 insertions(+)
create mode 100644 server/exports.c
diff --git a/include/nbdkit-common.h b/include/nbdkit-common.h
index 671cd4a4..d38b37d2 100644
--- a/include/nbdkit-common.h
+++ b/include/nbdkit-common.h
@@ -117,6 +117,10 @@ struct nbdkit_extents;
extern int nbdkit_add_extent (struct nbdkit_extents *,
uint64_t offset, uint64_t length, uint32_t type);
+struct nbdkit_exports;
+extern int nbdkit_add_export (struct nbdkit_exports *,
+ const char *name, const char *description);
+
/* A static non-NULL pointer which can be used when you don't need a
* per-connection handle.
*/
diff --git a/include/nbdkit-filter.h b/include/nbdkit-filter.h
index cec12db7..01ff3dce 100644
--- a/include/nbdkit-filter.h
+++ b/include/nbdkit-filter.h
@@ -123,6 +123,18 @@ extern int nbdkit_extents_aligned (struct nbdkit_next_ops *next_ops,
uint32_t flags, uint32_t align,
struct nbdkit_extents *extents, int *err);
+/* Export functions. */
+struct nbdkit_export {
+ char *name;
+ char *description;
+};
+
+extern struct nbdkit_exports *nbdkit_exports_new (int default_only);
+extern void nbdkit_exports_free (struct nbdkit_exports *);
+extern size_t nbdkit_exports_count (const struct nbdkit_exports *);
+extern const struct nbdkit_export nbdkit_get_export (const struct nbdkit_exports *,
+ size_t);
+
/* Filter struct. */
struct nbdkit_filter {
/* Do not set these fields directly; use NBDKIT_REGISTER_FILTER.
diff --git a/server/Makefile.am b/server/Makefile.am
index 4c789934..58b22341 100644
--- a/server/Makefile.am
+++ b/server/Makefile.am
@@ -43,6 +43,7 @@ nbdkit_SOURCES = \
crypto.c \
debug.c \
debug-flags.c \
+ exports.c \
extents.c \
filters.c \
internal.h \
@@ -139,6 +140,7 @@ check_PROGRAMS = test-public
test_public_SOURCES = \
test-public.c \
public.c \
+ exports.c \
extents.c \
$(NULL)
test_public_CPPFLAGS = \
diff --git a/common/utils/cleanup.h b/common/utils/cleanup.h
index bcb65f7b..6b59556b 100644
--- a/common/utils/cleanup.h
+++ b/common/utils/cleanup.h
@@ -76,5 +76,8 @@ extern void cleanup_rwlock_unlock (pthread_rwlock_t **ptr);
struct nbdkit_extents;
extern void cleanup_extents_free (struct nbdkit_extents **ptr);
#define CLEANUP_EXTENTS_FREE __attribute__((cleanup (cleanup_extents_free)))
+struct nbdkit_exports;
+extern void cleanup_exports_free (struct nbdkit_exports **ptr);
+#define CLEANUP_EXPORTS_FREE __attribute__((cleanup (cleanup_exports_free)))
#endif /* NBDKIT_CLEANUP_H */
diff --git a/server/exports.c b/server/exports.c
new file mode 100644
index 00000000..3f819622
--- /dev/null
+++ b/server/exports.c
@@ -0,0 +1,149 @@
+/* nbdkit
+ * Copyright (C) 2019-2020 Red Hat Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of Red Hat nor the names of its contributors may be
+ * used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include "vector.h"
+
+#include "internal.h"
+
+/* Cap nr_exports to avoid sending over-large replies to the client,
+ * and to avoid a plugin with large list consuming too much memory.
+ */
+#define MAX_EXPORTS 10000
+
+/* Appendable list of exports. */
+DEFINE_VECTOR_TYPE(exports, struct nbdkit_export);
+
+struct nbdkit_exports {
+ exports exports;
+
+ bool default_only;
+};
+
+struct nbdkit_exports *
+nbdkit_exports_new (int default_only)
+{
+ struct nbdkit_exports *r;
+
+ r = malloc (sizeof *r);
+ if (r == NULL) {
+ nbdkit_error ("nbdkit_exports_new: malloc: %m");
+ return NULL;
+ }
+ r->exports = (exports) empty_vector;
+ r->default_only = default_only != 0;
+ return r;
+}
+
+static void
+nbdkit_export_clear (struct nbdkit_export exp)
+{
+ free (exp.name);
+ free (exp.description);
+}
+
+void
+nbdkit_exports_free (struct nbdkit_exports *exps)
+{
+ if (exps) {
+ exports_iter (&exps->exports, nbdkit_export_clear);
+ free (exps->exports.ptr);
+ free (exps);
+ }
+}
+
+size_t
+nbdkit_exports_count (const struct nbdkit_exports *exps)
+{
+ return exps->exports.size;
+}
+
+const struct nbdkit_export
+nbdkit_get_export (const struct nbdkit_exports *exps, size_t i)
+{
+ assert (i < exps->exports.size);
+ return exps->exports.ptr[i];
+}
+
+int
+nbdkit_add_export (struct nbdkit_exports *exps,
+ const char *name, const char *description)
+{
+ struct nbdkit_export e = { NULL, NULL };
+
+ if (exps->default_only && exps->exports.size == 1)
+ return 0;
+
+ if (exps->exports.size == MAX_EXPORTS) {
+ nbdkit_error ("nbdkit_add_export: too many exports");
+ errno = EINVAL;
+ return -1;
+ }
+ if (strlen (name) > NBD_MAX_STRING ||
+ (description && strlen (description) > NBD_MAX_STRING)) {
+ nbdkit_error ("nbdkit_add_export: string too long");
+ errno = EINVAL;
+ return -1;
+ }
+
+ e.name = strdup (name);
+ if (e.name == NULL) {
+ nbdkit_error ("nbdkit_add_export: strdup: %m");
+ return -1;
+ }
+ if (description) {
+ e.description = strdup (description);
+ if (e.description == NULL) {
+ nbdkit_error ("nbdkit_add_export: strdup: %m");
+ free (e.name);
+ errno = ENOMEM;
+ return -1;
+ }
+ }
+
+ if (exports_append (&exps->exports, e) == -1) {
+ nbdkit_error ("nbdkit_add_export: realloc: %m");
+ free (e.name);
+ free (e.description);
+ errno = ENOMEM;
+ return -1;
+ }
+
+ return 0;
+}
diff --git a/server/nbdkit.syms b/server/nbdkit.syms
index d62ad484..6cc6ed32 100644
--- a/server/nbdkit.syms
+++ b/server/nbdkit.syms
@@ -39,10 +39,15 @@
# The functions we want plugins and filters to call.
global:
nbdkit_absolute_path;
+ nbdkit_add_export;
nbdkit_add_extent;
nbdkit_debug;
nbdkit_error;
nbdkit_export_name;
+ nbdkit_exports_count;
+ nbdkit_exports_free;
+ nbdkit_exports_new;
+ nbdkit_get_export;
nbdkit_extents_aligned;
nbdkit_extents_count;
nbdkit_extents_free;
diff --git a/common/utils/cleanup-nbdkit.c b/common/utils/cleanup-nbdkit.c
index aaaf14a0..e7553c73 100644
--- a/common/utils/cleanup-nbdkit.c
+++ b/common/utils/cleanup-nbdkit.c
@@ -43,3 +43,9 @@ cleanup_extents_free (struct nbdkit_extents **ptr)
{
nbdkit_extents_free (*ptr);
}
+
+void
+cleanup_exports_free (struct nbdkit_exports **ptr)
+{
+ nbdkit_exports_free (*ptr);
+}
--
2.28.0
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