Adding upstream version 2.1.30.upstream/2.1.30

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1332 insertions, 0 deletions

diff --git a/src/plugins_exts/schema_mount.c b/src/plugins_exts/schema_mount.c
new file mode 100644
index 0000000..9800760
--- /dev/null
+++ b/src/plugins_exts/schema_mount.c
@@ -0,0 +1,1332 @@
+/**
+ * @file schema_mount.c
+ * @author Tadeas Vintrlik <xvintr04@stud.fit.vutbr.cz>
+ * @brief libyang extension plugin - Schema Mount (RFC 8528)
+ *
+ * Copyright (c) 2021 CESNET, z.s.p.o.
+ *
+ * This source code is licensed under BSD 3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://opensource.org/licenses/BSD-3-Clause
+ */
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "common.h"
+#include "compat.h"
+#include "dict.h"
+#include "libyang.h"
+#include "log.h"
+#include "parser_data.h"
+#include "plugins_exts.h"
+#include "plugins_types.h"
+#include "tree_data.h"
+#include "tree_schema.h"
+
+/**
+ * @brief Internal schema mount data structure for holding all the contexts of parsed data.
+ */
+struct lyplg_ext_sm {
+    pthread_mutex_t lock;               /**< lock for accessing this shared structure */
+
+    struct lyplg_ext_sm_shared {
+        struct {
+            struct ly_ctx *ctx;         /**< context shared between all data of this mount point */
+            const char *mount_point;    /**< mount point name */
+            const char *content_id;     /**< yang-library content-id (alternatively module-set-id),
+                                             stored in the dictionary of the ext instance context */
+        } *schemas;                     /**< array of shared schema schemas */
+        uint32_t schema_count;          /**< length of schemas array */
+        uint32_t ref_count;             /**< number of references to this structure (mount-points with the same name
+                                             in the module) */
+    } *shared;                          /**< shared schema mount points */
+
+    struct lyplg_ext_sm_inln {
+        struct {
+            struct ly_ctx *ctx;         /**< context created for inline schema data, may be reused if possible */
+        } *schemas;                     /**< array of inline schemas */
+        uint32_t schema_count;          /**< length of schemas array */
+    } inln;                             /**< inline mount points */
+};
+
+struct sprinter_tree_priv {
+    struct ly_ctx *ext_ctx;
+    struct ly_set *refs;
+};
+
+#define EXT_LOGERR_MEM_RET(cctx, ext) \
+        lyplg_ext_compile_log(cctx, ext, LY_LLERR, LY_EMEM, "Memory allocation failed (%s:%d).", __FILE__, __LINE__); \
+        return LY_EMEM
+
+#define EXT_LOGERR_MEM_GOTO(cctx, ext, rc, label) \
+        lyplg_ext_compile_log(cctx, ext, LY_LLERR, LY_EMEM, "Memory allocation failed (%s:%d).", __FILE__, __LINE__); \
+        rc = LY_EMEM; \
+        goto label
+
+#define EXT_LOGERR_INT_RET(cctx, ext) \
+        lyplg_ext_compile_log(cctx, ext, LY_LLERR, LY_EINT, "Internal error (%s:%d).", __FILE__, __LINE__); \
+        return LY_EINT
+
+/**
+ * @brief Check if given mount point is unique among its siblings
+ *
+ * @param[in] pctx Parse context.
+ * @param[in] ext Parsed extension instance.
+ * @return LY_SUCCESS if is unique;
+ * @return LY_EINVAL otherwise.
+ */
+static LY_ERR
+schema_mount_parse_unique_mp(struct lysp_ctx *pctx, const struct lysp_ext_instance *ext)
+{
+    struct lysp_ext_instance *exts;
+    LY_ARRAY_COUNT_TYPE u;
+    struct lysp_node *parent;
+
+    /* check if it is the only instance of the mount-point among its siblings */
+    parent = ext->parent;
+    exts = parent->exts;
+    LY_ARRAY_FOR(exts, u) {
+        if (&exts[u] == ext) {
+            continue;
+        }
+
+        if (!strcmp(exts[u].name, ext->name)) {
+            lyplg_ext_parse_log(pctx, ext, LY_LLERR, LY_EVALID, "Multiple extension \"%s\" instances.", ext->name);
+            return LY_EINVAL;
+        }
+    }
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Schema mount parse.
+ * Checks if it can be a valid extension instance for yang schema mount.
+ *
+ * Implementation of ::lyplg_ext_parse_clb callback set as lyext_plugin::parse.
+ */
+static LY_ERR
+schema_mount_parse(struct lysp_ctx *pctx, struct lysp_ext_instance *ext)
+{
+    /* check YANG version 1.1 */
+    if (lyplg_ext_parse_get_cur_pmod(pctx)->version != LYS_VERSION_1_1) {
+        lyplg_ext_parse_log(pctx, ext, LY_LLERR, LY_EVALID, "Extension \"%s\" instance not allowed in YANG version 1 module.",
+                ext->name);
+        return LY_EINVAL;
+    }
+
+    /* check parent nodetype */
+    if ((ext->parent_stmt != LY_STMT_CONTAINER) && (ext->parent_stmt != LY_STMT_LIST)) {
+        lyplg_ext_parse_log(pctx, ext, LY_LLERR, LY_EVALID, "Extension \"%s\" instance allowed only in container or list statement.",
+                ext->name);
+        return LY_EINVAL;
+    }
+
+    /* check uniqueness */
+    if (schema_mount_parse_unique_mp(pctx, ext)) {
+        return LY_EINVAL;
+    }
+
+    /* nothing to actually parse */
+    return LY_SUCCESS;
+}
+
+struct lyplg_ext_sm_shared_cb_data {
+    const struct lysc_ext_instance *ext;
+    struct lyplg_ext_sm_shared *sm_shared;
+};
+
+static LY_ERR
+schema_mount_compile_mod_dfs_cb(struct lysc_node *node, void *data, ly_bool *UNUSED(dfs_continue))
+{
+    struct lyplg_ext_sm_shared_cb_data *cb_data = data;
+    struct lyplg_ext_sm *sm_data;
+    struct lysc_ext_instance *exts;
+    LY_ARRAY_COUNT_TYPE u;
+
+    if (node == cb_data->ext->parent) {
+        /* parent of the current compiled extension, skip */
+        return LY_SUCCESS;
+    }
+
+    /* find the same mount point */
+    exts = node->exts;
+    LY_ARRAY_FOR(exts, u) {
+        if (!strcmp(exts[u].def->module->name, "ietf-yang-schema-mount") && !strcmp(exts[u].def->name, "mount-point") &&
+                (exts[u].argument == cb_data->ext->argument)) {
+            /* same mount point, break the DFS search */
+            sm_data = exts[u].compiled;
+            cb_data->sm_shared = sm_data->shared;
+            return LY_EEXIST;
+        }
+    }
+
+    /* not found, continue search */
+    return LY_SUCCESS;
+}
+
+static struct lyplg_ext_sm_shared *
+schema_mount_compile_find_shared(const struct lys_module *mod, const struct lysc_ext_instance *ext)
+{
+    struct lyplg_ext_sm_shared_cb_data cb_data;
+    LY_ERR r;
+
+    /* prepare cb_data */
+    cb_data.ext = ext;
+    cb_data.sm_shared = NULL;
+
+    /* try to find the same mount point */
+    r = lysc_module_dfs_full(mod, schema_mount_compile_mod_dfs_cb, &cb_data);
+    (void)r;
+    assert((!r && !cb_data.sm_shared) || ((r == LY_EEXIST) && cb_data.sm_shared));
+
+    return cb_data.sm_shared;
+}
+
+/**
+ * @brief Schema mount compile.
+ * Checks if it can be a valid extension instance for yang schema mount.
+ *
+ * Implementation of ::lyplg_ext_compile_clb callback set as lyext_plugin::compile.
+ */
+static LY_ERR
+schema_mount_compile(struct lysc_ctx *cctx, const struct lysp_ext_instance *UNUSED(extp), struct lysc_ext_instance *ext)
+{
+    const struct lysc_node *node;
+    struct lyplg_ext_sm *sm_data;
+
+    /* init internal data */
+    sm_data = calloc(1, sizeof *sm_data);
+    if (!sm_data) {
+        EXT_LOGERR_MEM_RET(cctx, ext);
+    }
+    pthread_mutex_init(&sm_data->lock, NULL);
+    ext->compiled = sm_data;
+
+    /* find the owner module */
+    node = ext->parent;
+    while (node->parent) {
+        node = node->parent;
+    }
+
+    /* reuse/init shared schema */
+    sm_data->shared = schema_mount_compile_find_shared(node->module, ext);
+    if (sm_data->shared) {
+        ++sm_data->shared->ref_count;
+    } else {
+        sm_data->shared = calloc(1, sizeof *sm_data->shared);
+        if (!sm_data->shared) {
+            free(sm_data);
+            EXT_LOGERR_MEM_RET(cctx, ext);
+        }
+        sm_data->shared->ref_count = 1;
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Learn details about the current mount point.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[in] ext_data Extension data retrieved by the callback.
+ * @param[out] config Whether the whole schema should keep its config or be set to false.
+ * @param[out] shared Optional flag whether the schema is shared or inline.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_get_smount(const struct lysc_ext_instance *ext, const struct lyd_node *ext_data, ly_bool *config,
+        ly_bool *shared)
+{
+    struct lyd_node *mpoint, *node;
+    char *path = NULL;
+    LY_ERR r;
+
+    /* find the mount point */
+    if (asprintf(&path, "/ietf-yang-schema-mount:schema-mounts/mount-point[module='%s'][label='%s']", ext->module->name,
+            ext->argument) == -1) {
+        EXT_LOGERR_MEM_RET(NULL, ext);
+    }
+    r = ext_data ? lyd_find_path(ext_data, path, 0, &mpoint) : LY_ENOTFOUND;
+    free(path);
+    if (r) {
+        /* missing mount-point, cannot be data for this extension (https://datatracker.ietf.org/doc/html/rfc8528#page-10) */
+        return LY_ENOT;
+    }
+
+    /* check config */
+    *config = 1;
+    if (!lyd_find_path(mpoint, "config", 0, &node) && !strcmp(lyd_get_value(node), "false")) {
+        *config = 0;
+    }
+    assert((ext->parent_stmt == LY_STMT_CONTAINER) || (ext->parent_stmt == LY_STMT_LIST));
+    if (((struct lysc_node *)ext->parent)->flags & LYS_CONFIG_R) {
+        *config = 0;
+    }
+
+    if (shared) {
+        /* check schema-ref */
+        if (lyd_find_path(mpoint, "shared-schema", 0, NULL)) {
+            if (lyd_find_path(mpoint, "inline", 0, NULL)) {
+                EXT_LOGERR_INT_RET(NULL, ext);
+            }
+            *shared = 0;
+        } else {
+            *shared = 1;
+        }
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Create schema (context) based on retrieved extension data.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[in] ext_data Extension data retrieved by the callback.
+ * @param[in] config Whether the whole schema should keep its config or be set to false.
+ * @param[out] ext_ctx Schema to use for parsing the data.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_create_ctx(const struct lysc_ext_instance *ext, const struct lyd_node *ext_data, ly_bool config,
+        struct ly_ctx **ext_ctx)
+{
+    LY_ERR rc = LY_SUCCESS;
+    const char * const *searchdirs;
+    char *sdirs = NULL;
+    const struct lys_module *mod;
+    struct lysc_node *root, *node;
+    uint32_t i, idx = 0;
+
+    /* get searchdirs from the current context */
+    searchdirs = ly_ctx_get_searchdirs(ext->module->ctx);
+
+    if (searchdirs) {
+        /* append them all into a single string */
+        for (i = 0; searchdirs[i]; ++i) {
+            if ((rc = ly_strcat(&sdirs, "%s" PATH_SEPARATOR, searchdirs[i]))) {
+                goto cleanup;
+            }
+        }
+    }
+
+    /* create the context based on the data */
+    if ((rc = ly_ctx_new_yldata(sdirs, ext_data, ly_ctx_get_options(ext->module->ctx), ext_ctx))) {
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, rc, "Failed to create context for the schema-mount data.");
+        goto cleanup;
+    }
+
+    if (!config) {
+        /* manually change the config of all schema nodes in all the modules */
+        while ((mod = ly_ctx_get_module_iter(*ext_ctx, &idx))) {
+            if (!mod->implemented) {
+                continue;
+            }
+
+            LY_LIST_FOR(mod->compiled->data, root) {
+                LYSC_TREE_DFS_BEGIN(root, node) {
+                    node->flags &= ~LYS_CONFIG_W;
+                    node->flags |= LYS_CONFIG_R;
+
+                    LYSC_TREE_DFS_END(root, node);
+                }
+            }
+        }
+    }
+
+cleanup:
+    free(sdirs);
+    return rc;
+}
+
+/**
+ * @brief Get ietf-yang-library context-id from its data.
+ *
+ * @param[in] ext Compiled extension instance for logging.
+ * @param[in] ext_data Extension data retrieved by the callback with the yang-library data.
+ * @param[out] content_id Content ID in @p ext_data.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_get_content_id(struct lysc_ext_instance *ext, const struct lyd_node *ext_data, const char **content_id)
+{
+    struct lyd_node *node = NULL;
+
+    *content_id = NULL;
+
+    /* get yang-library content-id or module-set-id */
+    if (ext_data) {
+        lyd_find_path(ext_data, "/ietf-yang-library:yang-library/content-id", 0, &node);
+        if (!node) {
+            lyd_find_path(ext_data, "/ietf-yang-library:modules-state/module-set-id", 0, &node);
+        }
+        if (node) {
+            *content_id = lyd_get_value(node);
+        }
+    }
+
+    if (!*content_id) {
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_EVALID,
+                "Missing \"content-id\" or \"module-set-id\" in ietf-yang-library data.");
+        return LY_EVALID;
+    }
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Get schema (context) for a shared-schema mount point.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[in] ext_data Extension data retrieved by the callback.
+ * @param[in] config Whether the whole schema should keep its config or be set to false.
+ * @param[out] ext_ctx Schema to use for parsing the data.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_get_ctx_shared(struct lysc_ext_instance *ext, const struct lyd_node *ext_data, ly_bool config,
+        const struct ly_ctx **ext_ctx)
+{
+    struct lyplg_ext_sm *sm_data = ext->compiled;
+    LY_ERR rc = LY_SUCCESS, r;
+    struct ly_ctx *new_ctx = NULL;
+    uint32_t i;
+    const char *content_id;
+    void *mem;
+
+    assert(sm_data && sm_data->shared);
+
+    /* get yang-library content-id or module-set-id */
+    if ((r = schema_mount_get_content_id(ext, ext_data, &content_id))) {
+        return r;
+    }
+
+    /* LOCK */
+    if ((r = pthread_mutex_lock(&sm_data->lock))) {
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_ESYS, "Mutex lock failed (%s).", strerror(r));
+        return LY_ESYS;
+    }
+
+    /* try to find this mount point */
+    for (i = 0; i < sm_data->shared->schema_count; ++i) {
+        if (ext->argument == sm_data->shared->schemas[i].mount_point) {
+            break;
+        }
+    }
+
+    if (i < sm_data->shared->schema_count) {
+        /* schema exists already */
+        if (strcmp(content_id, sm_data->shared->schemas[i].content_id)) {
+            lyplg_ext_compile_log_path("/ietf-yang-library:yang-library/content-id", ext, LY_LLERR, LY_EVALID,
+                    "Shared-schema yang-library content-id \"%s\" differs from \"%s\" used previously.",
+                    content_id, sm_data->shared->schemas[i].content_id);
+            rc = LY_EVALID;
+            goto cleanup;
+        }
+    } else {
+        /* no schema found, create it */
+        if ((r = schema_mount_create_ctx(ext, ext_data, config, &new_ctx))) {
+            rc = r;
+            goto cleanup;
+        }
+
+        /* new entry */
+        mem = realloc(sm_data->shared->schemas, (i + 1) * sizeof *sm_data->shared->schemas);
+        if (!mem) {
+            ly_ctx_destroy(new_ctx);
+            EXT_LOGERR_MEM_GOTO(NULL, ext, rc, cleanup);
+        }
+        sm_data->shared->schemas = mem;
+        ++sm_data->shared->schema_count;
+
+        /* fill entry */
+        sm_data->shared->schemas[i].ctx = new_ctx;
+        sm_data->shared->schemas[i].mount_point = ext->argument;
+        lydict_insert(ext->module->ctx, content_id, 0, &sm_data->shared->schemas[i].content_id);
+    }
+
+    /* use the context */
+    *ext_ctx = sm_data->shared->schemas[i].ctx;
+
+cleanup:
+    /* UNLOCK */
+    pthread_mutex_unlock(&sm_data->lock);
+
+    return rc;
+}
+
+/**
+ * @brief Check whether ietf-yang-library data describe an existing context meaning whether it includes
+ * at least exactly all the mentioned modules.
+ *
+ * @param[in] ext Compiled extension instance for logging.
+ * @param[in] ext_data Extension data retrieved by the callback with the yang-library data.
+ * @param[in] ctx Context to consider.
+ * @return LY_SUCCESS if the context matches.
+ * @return LY_ENOT if the context differs.
+ * @return LY_ERR on error.
+ */
+static LY_ERR
+schema_mount_ctx_match(struct lysc_ext_instance *ext, const struct lyd_node *ext_data, const struct ly_ctx *ctx)
+{
+    struct ly_set *impl_mods = NULL, *imp_mods = NULL;
+    struct lyd_node *node;
+    const struct lys_module *mod;
+    const char *name, *revision;
+    LY_ERR rc = LY_ENOT, r;
+    uint32_t i;
+
+    /* collect all the implemented and imported modules, we do not really care about content-id */
+    if (!lyd_find_path(ext_data, "/ietf-yang-library:yang-library/content-id", 0, NULL)) {
+        if ((r = lyd_find_xpath(ext_data, "/ietf-yang-library:yang-library/module-set[1]/module", &impl_mods))) {
+            rc = r;
+            goto cleanup;
+        }
+        if ((r = lyd_find_xpath(ext_data, "/ietf-yang-library:yang-library/module-set[1]/import-only-module", &imp_mods))) {
+            rc = r;
+            goto cleanup;
+        }
+    } else {
+        if ((r = lyd_find_xpath(ext_data, "/ietf-yang-library:modules-state/module[conformance-type='implement']", &impl_mods))) {
+            rc = r;
+            goto cleanup;
+        }
+        if ((r = lyd_find_xpath(ext_data, "/ietf-yang-library:modules-state/module[conformance-type='import']", &imp_mods))) {
+            rc = r;
+            goto cleanup;
+        }
+    }
+
+    if (!impl_mods->count) {
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_EVALID, "No implemented modules included in ietf-yang-library data.");
+        rc = LY_EVALID;
+        goto cleanup;
+    }
+
+    /* check all the implemented modules */
+    for (i = 0; i < impl_mods->count; ++i) {
+        lyd_find_path(impl_mods->dnodes[i], "name", 0, &node);
+        name = lyd_get_value(node);
+
+        lyd_find_path(impl_mods->dnodes[i], "revision", 0, &node);
+        if (node && strlen(lyd_get_value(node))) {
+            revision = lyd_get_value(node);
+        } else {
+            revision = NULL;
+        }
+
+        if (!(mod = ly_ctx_get_module(ctx, name, revision)) || !mod->implemented) {
+            /* unsuitable module */
+            goto cleanup;
+        }
+    }
+
+    /* check all the imported modules */
+    for (i = 0; i < imp_mods->count; ++i) {
+        lyd_find_path(imp_mods->dnodes[i], "name", 0, &node);
+        name = lyd_get_value(node);
+
+        lyd_find_path(imp_mods->dnodes[i], "revision", 0, &node);
+        if (node && strlen(lyd_get_value(node))) {
+            revision = lyd_get_value(node);
+        } else {
+            revision = NULL;
+        }
+
+        if (!ly_ctx_get_module(ctx, name, revision)) {
+            /* unsuitable module */
+            goto cleanup;
+        }
+    }
+
+    /* context matches and can be reused */
+    rc = LY_SUCCESS;
+
+cleanup:
+    ly_set_free(impl_mods, NULL);
+    ly_set_free(imp_mods, NULL);
+    return rc;
+}
+
+/**
+ * @brief Get schema (context) for an inline mount point.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[in] ext_data Extension data retrieved by the callback.
+ * @param[in] config Whether the whole schema should keep its config or be set to false.
+ * @param[out] ext_ctx Schema to use for parsing the data.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_get_ctx_inline(struct lysc_ext_instance *ext, const struct lyd_node *ext_data, ly_bool config,
+        const struct ly_ctx **ext_ctx)
+{
+    struct lyplg_ext_sm *sm_data = ext->compiled;
+    struct ly_ctx *new_ctx = NULL;
+    uint32_t i;
+    void *mem;
+    LY_ERR rc = LY_SUCCESS, r;
+
+    assert(sm_data && sm_data->shared);
+
+    /* LOCK */
+    if ((r = pthread_mutex_lock(&sm_data->lock))) {
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_ESYS, "Mutex lock failed (%s).", strerror(r));
+        return LY_ESYS;
+    }
+
+    /* try to find a context we can reuse */
+    for (i = 0; i < sm_data->inln.schema_count; ++i) {
+        r = schema_mount_ctx_match(ext, ext_data, sm_data->inln.schemas[i].ctx);
+        if (!r) {
+            /* match */
+            *ext_ctx = sm_data->inln.schemas[i].ctx;
+            goto cleanup;
+        } else if (r != LY_ENOT) {
+            /* error */
+            rc = r;
+            goto cleanup;
+        }
+    }
+
+    /* new schema required, create context */
+    if ((r = schema_mount_create_ctx(ext, ext_data, config, &new_ctx))) {
+        rc = r;
+        goto cleanup;
+    }
+
+    /* new entry */
+    mem = realloc(sm_data->inln.schemas, (i + 1) * sizeof *sm_data->inln.schemas);
+    if (!mem) {
+        ly_ctx_destroy(new_ctx);
+        EXT_LOGERR_MEM_GOTO(NULL, ext, rc, cleanup);
+    }
+    sm_data->inln.schemas = mem;
+    ++sm_data->inln.schema_count;
+
+    /* fill entry */
+    sm_data->inln.schemas[i].ctx = new_ctx;
+
+    /* use the context */
+    *ext_ctx = sm_data->inln.schemas[i].ctx;
+
+cleanup:
+    /* UNLOCK */
+    pthread_mutex_unlock(&sm_data->lock);
+
+    return rc;
+}
+
+/**
+ * @brief Get schema (context) for a mount point.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[out] ext_ctx Schema to use for parsing the data.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_get_ctx(struct lysc_ext_instance *ext, const struct ly_ctx **ext_ctx)
+{
+    LY_ERR ret = LY_SUCCESS, r;
+    struct lyd_node *iter, *ext_data = NULL;
+    ly_bool ext_data_free = 0, config, shared;
+
+    *ext_ctx = NULL;
+
+    /* get operational data with ietf-yang-library and ietf-yang-schema-mount data */
+    if ((r = lyplg_ext_get_data(ext->module->ctx, ext, (void **)&ext_data, &ext_data_free))) {
+        ret = r;
+        goto cleanup;
+    }
+
+    LY_LIST_FOR(ext_data, iter) {
+        if (iter->flags & LYD_NEW) {
+            /* must be validated for the parent-reference prefix data to be stored */
+            lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_EINVAL, "Provided ext data have not been validated.");
+            ret = LY_EINVAL;
+            goto cleanup;
+        }
+    }
+
+    /* learn about this mount point */
+    if ((r = schema_mount_get_smount(ext, ext_data, &config, &shared))) {
+        ret = r;
+        goto cleanup;
+    }
+
+    /* create/get the context for parsing the data */
+    if (shared) {
+        r = schema_mount_get_ctx_shared(ext, ext_data, config, ext_ctx);
+    } else {
+        r = schema_mount_get_ctx_inline(ext, ext_data, config, ext_ctx);
+    }
+    if (r) {
+        ret = r;
+        goto cleanup;
+    }
+
+cleanup:
+    if (ext_data_free) {
+        lyd_free_all(ext_data);
+    }
+    return ret;
+}
+
+/**
+ * @brief Snode callback for schema mount.
+ * Check if data are valid for schema mount and returns their schema node.
+ */
+static LY_ERR
+schema_mount_snode(struct lysc_ext_instance *ext, const struct lyd_node *parent, const struct lysc_node *sparent,
+        const char *prefix, size_t prefix_len, LY_VALUE_FORMAT format, void *prefix_data, const char *name, size_t name_len,
+        const struct lysc_node **snode)
+{
+    LY_ERR r;
+    const struct lys_module *mod;
+    const struct ly_ctx *ext_ctx = NULL;
+
+    /* get context based on ietf-yang-library data */
+    if ((r = schema_mount_get_ctx(ext, &ext_ctx))) {
+        return r;
+    }
+
+    /* get the module */
+    mod = lyplg_type_identity_module(ext_ctx, parent ? parent->schema : sparent, prefix, prefix_len, format, prefix_data);
+    if (!mod) {
+        return LY_ENOT;
+    }
+
+    /* get the top-level schema node */
+    *snode = lys_find_child(NULL, mod, name, name_len, 0, 0);
+    return *snode ? LY_SUCCESS : LY_ENOT;
+}
+
+static LY_ERR
+schema_mount_get_parent_ref(const struct lysc_ext_instance *ext, const struct lyd_node *ext_data,
+        struct ly_set **set)
+{
+    LY_ERR ret = LY_SUCCESS;
+    char *path = NULL;
+
+    /* get all parent references of this mount point */
+    if (asprintf(&path, "/ietf-yang-schema-mount:schema-mounts/mount-point[module='%s'][label='%s']"
+            "/shared-schema/parent-reference", ext->module->name, ext->argument) == -1) {
+        EXT_LOGERR_MEM_GOTO(NULL, ext, ret, cleanup);
+    }
+    if ((ret = lyd_find_xpath(ext_data, path, set))) {
+        goto cleanup;
+    }
+
+cleanup:
+    free(path);
+    return ret;
+}
+
+/**
+ * @brief Duplicate all accessible parent references for a shared-schema mount point.
+ *
+ * @param[in] ext Compiled extension instance.
+ * @param[in] ctx_node Context node for evaluating the parent-reference XPath expressions.
+ * @param[in] ext_data Extension data retrieved by the callback.
+ * @param[in] trg_ctx Mounted data context to use for duplication.
+ * @param[out] ref_set Set of all top-level parent-ref subtrees connected to each other, may be empty.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+schema_mount_dup_parent_ref(const struct lysc_ext_instance *ext, const struct lyd_node *ctx_node,
+        const struct lyd_node *ext_data, const struct ly_ctx *trg_ctx, struct ly_set **ref_set)
+{
+    LY_ERR ret = LY_SUCCESS;
+    char *path = NULL;
+    struct ly_set *set = NULL, *par_set = NULL;
+    struct lyd_node_term *term;
+    struct lyd_node *dup = NULL, *top_node, *first;
+    struct lyd_value_xpath10 *xp_val;
+    uint32_t i, j;
+
+    *ref_set = NULL;
+
+    if (!ext_data) {
+        /* we expect the same ext data as before and there must be some for data to be parsed */
+        lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_EINVAL, "No ext data provided.");
+        ret = LY_EINVAL;
+        goto cleanup;
+    }
+
+    if ((ret = schema_mount_get_parent_ref(ext, ext_data, &set))) {
+        goto cleanup;
+    }
+
+    /* prepare result set */
+    if ((ret = ly_set_new(ref_set))) {
+        goto cleanup;
+    }
+
+    first = NULL;
+    for (i = 0; i < set->count; ++i) {
+        term = set->objs[i];
+
+        /* get the referenced nodes (subtrees) */
+        LYD_VALUE_GET(&term->value, xp_val);
+        if ((ret = lyd_find_xpath4(ctx_node, ctx_node, lyxp_get_expr(xp_val->exp), xp_val->format, xp_val->prefix_data,
+                NULL, &par_set))) {
+            lyplg_ext_compile_log(NULL, ext, LY_LLERR, ret, "Parent reference \"%s\" evaluation failed.",
+                    lyxp_get_expr(xp_val->exp));
+            goto cleanup;
+        }
+
+        for (j = 0; j < par_set->count; ++j) {
+            /* duplicate with parents in the context of the mounted data */
+            if ((ret = lyd_dup_single_to_ctx(par_set->dnodes[j], trg_ctx, NULL,
+                    LYD_DUP_RECURSIVE | LYD_DUP_WITH_PARENTS | LYD_DUP_WITH_FLAGS | LYD_DUP_NO_EXT, &dup))) {
+                goto cleanup;
+            }
+
+            /* go top-level */
+            while (dup->parent) {
+                dup = lyd_parent(dup);
+            }
+
+            /* check whether the top-level node exists */
+            if (first) {
+                if ((ret = lyd_find_sibling_first(first, dup, &top_node)) && (ret != LY_ENOTFOUND)) {
+                    goto cleanup;
+                }
+            } else {
+                top_node = NULL;
+            }
+
+            if (top_node) {
+                /* merge */
+                ret = lyd_merge_tree(&first, dup, LYD_MERGE_DESTRUCT);
+                dup = NULL;
+                if (ret) {
+                    goto cleanup;
+                }
+            } else {
+                /* insert */
+                if ((ret = lyd_insert_sibling(first, dup, &first))) {
+                    goto cleanup;
+                }
+
+                /* add into the result set because a new top-level node was added */
+                if ((ret = ly_set_add(*ref_set, dup, 1, NULL))) {
+                    goto cleanup;
+                }
+                dup = NULL;
+            }
+        }
+    }
+
+cleanup:
+    free(path);
+    ly_set_free(set, NULL);
+    ly_set_free(par_set, NULL);
+    lyd_free_tree(dup);
+    if (ret && *ref_set) {
+        if ((*ref_set)->count) {
+            lyd_free_siblings((*ref_set)->dnodes[0]);
+        }
+        ly_set_free(*ref_set, NULL);
+        *ref_set = NULL;
+    }
+    return ret;
+}
+
+LY_ERR
+lyplg_ext_schema_mount_get_parent_ref(const struct lysc_ext_instance *ext, struct ly_set **refs)
+{
+    LY_ERR rc;
+    struct ly_set *pref_set = NULL;
+    struct ly_set *snode_set = NULL;
+    struct ly_set *results_set = NULL;
+    struct lyd_node *ext_data;
+    ly_bool ext_data_free;
+
+    /* get operational data with ietf-yang-library and ietf-yang-schema-mount data */
+    if ((rc = lyplg_ext_get_data(ext->module->ctx, ext, (void **)&ext_data, &ext_data_free))) {
+        return rc;
+    }
+
+    LY_CHECK_GOTO(rc = schema_mount_get_parent_ref(ext, ext_data, &pref_set), cleanup);
+    if (pref_set->count == 0) {
+        goto cleanup;
+    }
+
+    LY_CHECK_GOTO(rc = ly_set_new(&results_set), cleanup);
+
+    for (uint32_t i = 0; i < pref_set->count; ++i) {
+        struct lyd_node_term *term;
+        struct lyd_value_xpath10 *xp_val;
+        char *value;
+        struct ly_err_item *err;
+
+        term = (struct lyd_node_term *)pref_set->dnodes[i];
+        LYD_VALUE_GET(&term->value, xp_val);
+        LY_CHECK_GOTO(rc = lyplg_type_print_xpath10_value(xp_val, LY_VALUE_JSON, NULL, &value, &err), cleanup);
+        LY_CHECK_ERR_GOTO(rc = lys_find_xpath(ext->module->ctx, NULL, value, 0, &snode_set), free(value), cleanup);
+        free(value);
+        for (uint32_t sn = 0; sn < snode_set->count; sn++) {
+            LY_CHECK_GOTO(rc = ly_set_add(results_set, snode_set->snodes[sn], 0, NULL), cleanup);
+        }
+        ly_set_free(snode_set, NULL);
+        snode_set = NULL;
+    }
+
+    *refs = results_set;
+
+cleanup:
+    if (rc) {
+        ly_set_free(results_set, NULL);
+    }
+    ly_set_free(snode_set, NULL);
+    if (ext_data_free) {
+        lyd_free_all(ext_data);
+    }
+    ly_set_free(pref_set, NULL);
+
+    return rc;
+}
+
+/**
+ * @brief Validate callback for schema mount.
+ */
+static LY_ERR
+schema_mount_validate(struct lysc_ext_instance *ext, struct lyd_node *sibling, const struct lyd_node *dep_tree,
+        enum lyd_type data_type, uint32_t val_opts, struct lyd_node **diff)
+{
+    LY_ERR ret = LY_SUCCESS;
+    uint32_t temp_lo = LY_LOSTORE_LAST, i;
+    struct ly_err_item *err;
+    struct lyd_node *iter, *ext_data = NULL, *ref_first = NULL, *orig_parent = lyd_parent(sibling), *op_tree;
+    struct lyd_node *ext_diff = NULL, *diff_parent = NULL;
+    ly_bool ext_data_free = 0;
+    struct ly_set *ref_set = NULL;
+
+    if (!sibling) {
+        /* some data had to be parsed for this callback to be called */
+        EXT_LOGERR_INT_RET(NULL, ext);
+    }
+
+    /* get operational data with ietf-yang-library and ietf-yang-schema-mount data */
+    if ((ret = lyplg_ext_get_data(ext->module->ctx, ext, (void **)&ext_data, &ext_data_free))) {
+        goto cleanup;
+    }
+
+    LY_LIST_FOR(ext_data, iter) {
+        if (iter->flags & LYD_NEW) {
+            /* must be validated for the parent-reference prefix data to be stored */
+            lyplg_ext_compile_log(NULL, ext, LY_LLERR, LY_EINVAL, "Provided ext data have not been validated.");
+            ret = LY_EINVAL;
+            goto cleanup;
+        }
+    }
+
+    /* duplicate the referenced parent nodes into ext context */
+    if ((ret = schema_mount_dup_parent_ref(ext, orig_parent, ext_data, LYD_CTX(sibling), &ref_set))) {
+        goto cleanup;
+    }
+
+    if (data_type != LYD_TYPE_DATA_YANG) {
+        /* remember the operation data tree, it may be moved */
+        op_tree = sibling;
+    }
+
+    /* create accessible tree, remove LYD_EXT to not call this callback recursively */
+    lyd_unlink_siblings(sibling);
+    LY_LIST_FOR(sibling, iter) {
+        iter->flags &= ~LYD_EXT;
+    }
+    if (ref_set->count) {
+        if ((ret = lyd_insert_sibling(sibling, ref_set->dnodes[0], &sibling))) {
+            goto cleanup;
+        }
+    }
+
+    /* only store messages in the context, log as an extension */
+    ly_temp_log_options(&temp_lo);
+
+    if (data_type == LYD_TYPE_DATA_YANG) {
+        /* validate all the modules with data */
+        ret = lyd_validate_all(&sibling, NULL, val_opts | LYD_VALIDATE_PRESENT, diff ? &ext_diff : NULL);
+    } else {
+        /* validate the operation */
+        ret = lyd_validate_op(op_tree, dep_tree, data_type, diff ? &ext_diff : NULL);
+    }
+
+    /* restore logging */
+    ly_temp_log_options(NULL);
+
+    /* restore sibling tree */
+    for (i = 0; i < ref_set->count; ++i) {
+        if (ref_set->dnodes[i] == sibling) {
+            sibling = sibling->next;
+        }
+        lyd_free_tree(ref_set->dnodes[i]);
+    }
+    LY_LIST_FOR(sibling, iter) {
+        iter->flags |= LYD_EXT;
+    }
+    lyplg_ext_insert(orig_parent, sibling);
+
+    if (ret) {
+        /* log the error in the original context */
+        err = ly_err_first(LYD_CTX(sibling));
+        if (!err) {
+            lyplg_ext_compile_log(NULL, ext, LY_LLERR, ret, "Unknown validation error (err code %d).", ret);
+        } else {
+            lyplg_ext_compile_log_path(err->path, ext, LY_LLERR, err->no, "%s", err->msg);
+        }
+        goto cleanup;
+    }
+
+    /* create proper diff */
+    if (diff && ext_diff) {
+        /* diff nodes from an extension instance */
+        LY_LIST_FOR(ext_diff, iter) {
+            iter->flags |= LYD_EXT;
+        }
+
+        /* create the parent and insert the diff */
+        if ((ret = lyd_dup_single(lyd_parent(sibling), NULL, LYD_DUP_WITH_PARENTS | LYD_DUP_NO_META, &diff_parent))) {
+            goto cleanup;
+        }
+        if ((ret = lyplg_ext_insert(diff_parent, ext_diff))) {
+            goto cleanup;
+        }
+        ext_diff = NULL;
+
+        /* go top-level and set the operation */
+        while (lyd_parent(diff_parent)) {
+            diff_parent = lyd_parent(diff_parent);
+        }
+        if ((ret = lyd_new_meta(LYD_CTX(diff_parent), diff_parent, NULL, "yang:operation", "none", 0, NULL))) {
+            goto cleanup;
+        }
+
+        /* finally merge into the global diff */
+        if ((ret = lyd_diff_merge_all(diff, diff_parent, LYD_DIFF_MERGE_DEFAULTS))) {
+            goto cleanup;
+        }
+    }
+
+cleanup:
+    ly_set_free(ref_set, NULL);
+    lyd_free_siblings(ref_first);
+    lyd_free_tree(ext_diff);
+    lyd_free_all(diff_parent);
+    if (ext_data_free) {
+        lyd_free_all(ext_data);
+    }
+    return ret;
+}
+
+/**
+ * @brief Schema mount compile free.
+ *
+ * Implementation of ::lyplg_ext_compile_free_clb callback set as ::lyext_plugin::cfree.
+ */
+static void
+schema_mount_cfree(const struct ly_ctx *ctx, struct lysc_ext_instance *ext)
+{
+    struct lyplg_ext_sm *sm_data = ext->compiled;
+    uint32_t i;
+
+    if (!sm_data) {
+        return;
+    }
+
+    if (!--sm_data->shared->ref_count) {
+        for (i = 0; i < sm_data->shared->schema_count; ++i) {
+            ly_ctx_destroy(sm_data->shared->schemas[i].ctx);
+            lydict_remove(ctx, sm_data->shared->schemas[i].content_id);
+        }
+        free(sm_data->shared->schemas);
+        free(sm_data->shared);
+    }
+
+    for (i = 0; i < sm_data->inln.schema_count; ++i) {
+        ly_ctx_destroy(sm_data->inln.schemas[i].ctx);
+    }
+    free(sm_data->inln.schemas);
+
+    pthread_mutex_destroy(&sm_data->lock);
+    free(sm_data);
+}
+
+LIBYANG_API_DEF LY_ERR
+lyplg_ext_schema_mount_create_context(const struct lysc_ext_instance *ext, struct ly_ctx **ctx)
+{
+    struct lyd_node *ext_data = NULL;
+    ly_bool ext_data_free = 0, config;
+    LY_ERR rc = LY_SUCCESS;
+
+    if (!ext->module->ctx->ext_clb) {
+        return LY_EINVAL;
+    }
+
+    if (strcmp(ext->def->module->name, "ietf-yang-schema-mount") || strcmp(ext->def->name, "mount-point")) {
+        return LY_EINVAL;
+    }
+
+    /* get operational data with ietf-yang-library and ietf-yang-schema-mount data */
+    if ((rc = lyplg_ext_get_data(ext->module->ctx, ext, (void **)&ext_data, &ext_data_free))) {
+        return rc;
+    }
+
+    /* learn about this mount point */
+    if ((rc = schema_mount_get_smount(ext, ext_data, &config, NULL))) {
+        goto cleanup;
+    }
+
+    /* create the context */
+    rc = schema_mount_create_ctx(ext, ext_data, config, ctx);
+
+cleanup:
+    if (ext_data_free) {
+        lyd_free_all(ext_data);
+    }
+    return rc;
+}
+
+static void
+schema_mount_spriter_tree_free(void *priv)
+{
+    struct sprinter_tree_priv *st_priv;
+
+    st_priv = priv;
+    ly_set_free(st_priv->refs, NULL);
+    ly_ctx_destroy(st_priv->ext_ctx);
+    free(st_priv);
+}
+
+static LY_ERR
+schema_mount_sprinter_tree_cnode_override_mounted(const struct lysc_node *node, const void *UNUSED(plugin_priv),
+        ly_bool *UNUSED(skip), const char **UNUSED(flags), const char **add_opts)
+{
+    if (!node->parent) {
+        *add_opts = "/";
+    }
+
+    return LY_SUCCESS;
+}
+
+static LY_ERR
+schema_mount_sprinter_tree_pnode_override_mounted(const struct lysp_node *node, const void *UNUSED(plugin_priv),
+        ly_bool *UNUSED(skip), const char **UNUSED(flags), const char **add_opts)
+{
+    if (!node->parent) {
+        *add_opts = "/";
+    }
+
+    return LY_SUCCESS;
+}
+
+static LY_ERR
+schema_mount_sprinter_tree_node_override_parent_refs(const struct lysc_node *node, const void *plugin_priv,
+        ly_bool *skip, const char **UNUSED(flags), const char **add_opts)
+{
+    uint32_t i;
+    const struct ly_set *refs;
+    const struct lysc_module *mod;
+    struct lysc_node *ref, *iter;
+
+    refs = ((struct sprinter_tree_priv *)plugin_priv)->refs;
+    mod = node->module->compiled;
+
+    /* Assume the @p node will be skipped. */
+    *skip = 1;
+    for (i = 0; (i < refs->count) && *skip; i++) {
+        ref = refs->snodes[i];
+        if (ref->module->compiled != mod) {
+            /* parent-reference points to different module */
+            continue;
+        }
+
+        for (iter = ref; iter; iter = iter->parent) {
+            if (iter == node) {
+                /* @p node is not skipped because it is parent-rererence node or his parent */
+                *skip = 0;
+                break;
+            }
+        }
+    }
+
+    if (!*skip && !node->parent) {
+        /* top-node has additional opts */
+        *add_opts = "@";
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Schema mount schema parsed tree printer.
+ *
+ * Implementation of ::lyplg_ext_sprinter_ptree_clb callback set as lyext_plugin::printer_ptree.
+ */
+static LY_ERR
+schema_mount_sprinter_ptree(struct lysp_ext_instance *UNUSED(ext), const struct lyspr_tree_ctx *ctx,
+        const char **flags, const char **UNUSED(add_opts))
+{
+    if (!ctx) {
+        *flags = "mp";
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Schema mount schema compiled tree printer.
+ *
+ * Implementation of ::lyplg_ext_sprinter_ctree_clb callback set as lyext_plugin::printer_ctree.
+ */
+static LY_ERR
+schema_mount_sprinter_ctree(struct lysc_ext_instance *ext, const struct lyspr_tree_ctx *ctx,
+        const char **flags, const char **UNUSED(add_opts))
+{
+    LY_ERR rc = LY_SUCCESS;
+    struct ly_ctx *ext_ctx = NULL;
+    const struct lys_module *mod;
+    struct ly_set *refs = NULL;
+    struct lysc_node *tree1, *tree2;
+    uint32_t i, j;
+    ly_bool from_parent_ref, is_first;
+    struct sprinter_tree_priv *st_priv;
+
+    if (!ctx) {
+        *flags = "mp";
+        return LY_SUCCESS;
+    }
+
+    if (lyplg_ext_schema_mount_create_context(ext, &ext_ctx)) {
+        /* Void mount point */
+        return LY_SUCCESS;
+    }
+
+    rc = lyplg_ext_schema_mount_get_parent_ref(ext, &refs);
+    LY_CHECK_GOTO(rc, cleanup);
+
+    /* build new list of modules to print. This list will omit internal
+     * modules, modules with no nodes (e.g., iana-if-types) and modules
+     * that were loaded as the result of a parent-reference.
+     */
+    i = ly_ctx_internal_modules_count(ext_ctx);
+    while ((mod = ly_ctx_get_module_iter(ext_ctx, &i))) {
+        from_parent_ref = 0;
+
+        for (j = 0; refs && j < refs->count; j++) {
+            if (!strcmp(mod->ns, refs->snodes[j]->module->ns)) {
+                from_parent_ref = 1;
+                break;
+            }
+        }
+        if (from_parent_ref) {
+            /* Modules loaded as the result of a parent-reference are added later. */
+            continue;
+        }
+
+        /* Add data nodes, rpcs and notifications. */
+        if ((ext_ctx->flags & LY_CTX_SET_PRIV_PARSED) && mod->compiled) {
+            /* For compiled module. */
+            rc = lyplg_ext_sprinter_ctree_add_nodes(ctx, mod->compiled->data,
+                    schema_mount_sprinter_tree_cnode_override_mounted);
+            LY_CHECK_GOTO(rc, cleanup);
+            if (mod->compiled->rpcs) {
+                rc = lyplg_ext_sprinter_ctree_add_nodes(ctx, &mod->compiled->rpcs->node,
+                        schema_mount_sprinter_tree_cnode_override_mounted);
+            }
+            LY_CHECK_GOTO(rc, cleanup);
+            if (mod->compiled->notifs) {
+                rc = lyplg_ext_sprinter_ctree_add_nodes(ctx, &mod->compiled->notifs->node,
+                        schema_mount_sprinter_tree_cnode_override_mounted);
+            }
+            LY_CHECK_GOTO(rc, cleanup);
+        } else {
+            /* For parsed module. */
+            rc = lyplg_ext_sprinter_ptree_add_nodes(ctx, mod->parsed->data,
+                    schema_mount_sprinter_tree_pnode_override_mounted);
+            LY_CHECK_GOTO(rc, cleanup);
+            if (mod->parsed->rpcs) {
+                rc = lyplg_ext_sprinter_ptree_add_nodes(ctx, &mod->parsed->rpcs->node,
+                        schema_mount_sprinter_tree_pnode_override_mounted);
+            }
+            LY_CHECK_GOTO(rc, cleanup);
+            if (mod->parsed->notifs) {
+                rc = lyplg_ext_sprinter_ptree_add_nodes(ctx, &mod->parsed->notifs->node,
+                        schema_mount_sprinter_tree_pnode_override_mounted);
+            }
+            LY_CHECK_GOTO(rc, cleanup);
+        }
+    }
+
+    /* Add modules loaded as the result of a parent-reference. */
+    for (i = 0; refs && (i < refs->count); i++) {
+        tree1 = refs->snodes[i]->module->compiled->data;
+
+        /* Add data nodes from the module only once. */
+        is_first = 1;
+        for (j = 0; j < i; j++) {
+            tree2 = refs->snodes[j]->module->compiled->data;
+            if (tree1 == tree2) {
+                is_first = 0;
+                break;
+            }
+        }
+        if (is_first) {
+            /* Add all data nodes but unavailable nodes are skipped in the callback. */
+            rc = lyplg_ext_sprinter_ctree_add_nodes(ctx, tree1, schema_mount_sprinter_tree_node_override_parent_refs);
+            LY_CHECK_GOTO(rc, cleanup);
+        }
+    }
+
+    /* add private plugin data */
+    st_priv = calloc(1, sizeof(*st_priv));
+    LY_CHECK_ERR_GOTO(!st_priv, rc = LY_EMEM, cleanup);
+    st_priv->ext_ctx = ext_ctx;
+    st_priv->refs = refs;
+    rc = lyplg_ext_sprinter_tree_set_priv(ctx, st_priv, schema_mount_spriter_tree_free);
+
+cleanup:
+    if (rc) {
+        ly_set_free(refs, NULL);
+        ly_ctx_destroy(ext_ctx);
+    }
+
+    return rc;
+}
+
+/**
+ * @brief Plugin descriptions for the Yang Schema Mount extension.
+ *
+ * Note that external plugins are supposed to use:
+ *
+ *   LYPLG_EXTENSIONS = {
+ */
+const struct lyplg_ext_record plugins_schema_mount[] = {
+    {
+        .module = "ietf-yang-schema-mount",
+        .revision = "2019-01-14",
+        .name = "mount-point",
+
+        .plugin.id = "ly2 schema mount v1",
+        .plugin.parse = schema_mount_parse,
+        .plugin.compile = schema_mount_compile,
+        .plugin.printer_info = NULL,
+        .plugin.printer_ctree = schema_mount_sprinter_ctree,
+        .plugin.printer_ptree = schema_mount_sprinter_ptree,
+        .plugin.node = NULL,
+        .plugin.snode = schema_mount_snode,
+        .plugin.validate = schema_mount_validate,
+        .plugin.pfree = NULL,
+        .plugin.cfree = schema_mount_cfree
+    },
+    {0} /* terminating zeroed item */
+};