Adding upstream version 2.1.30.upstream/2.1.30

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

1 files changed, 1402 insertions, 0 deletions

diff --git a/src/xml.c b/src/xml.c
new file mode 100644
index 0000000..97e6abb
--- /dev/null
+++ b/src/xml.c
@@ -0,0 +1,1402 @@
+/**
+ * @file xml.c
+ * @author Radek Krejci <rkrejci@cesnet.cz>
+ * @author Michal Vasko <mvasko@cesnet.cz>
+ * @brief Generic XML parser implementation for libyang
+ *
+ * Copyright (c) 2015 - 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 "xml.h"
+
+#include <assert.h>
+#include <ctype.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "common.h"
+#include "compat.h"
+#include "in_internal.h"
+#include "out_internal.h"
+#include "tree.h"
+#include "tree_schema_internal.h"
+
+/* Move input p by s characters, if EOF log with lyxml_ctx c */
+#define move_input(c, s) \
+    ly_in_skip(c->in, s); \
+    LY_CHECK_ERR_RET(!c->in->current[0], LOGVAL(c->ctx, LY_VCODE_EOF), LY_EVALID)
+
+/* Ignore whitespaces in the input string p */
+#define ign_xmlws(c) \
+    while (is_xmlws(*(c)->in->current)) { \
+        if (*(c)->in->current == '\n') {  \
+            LY_IN_NEW_LINE((c)->in);      \
+        }                                 \
+        ly_in_skip(c->in, 1);             \
+    }
+
+static LY_ERR lyxml_next_attr_content(struct lyxml_ctx *xmlctx, const char **value, size_t *value_len, ly_bool *ws_only,
+        ly_bool *dynamic);
+
+/**
+ * @brief Ignore and skip any characters until the delim of the size delim_len is read, including the delim
+ *
+ * @param[in] xmlctx XML parser context to provide input handler and libyang context
+ * @param[in] in input handler to read the data, it is updated only in case the section is correctly terminated.
+ * @param[in] delim Delimiter to detect end of the section.
+ * @param[in] delim_len Length of the delimiter string to use.
+ * @param[in] sectname Section name to refer in error message.
+ */
+LY_ERR
+skip_section(struct lyxml_ctx *xmlctx, const char *delim, size_t delim_len, const char *sectname)
+{
+    size_t i;
+    register const char *input, *a, *b;
+    uint64_t parsed = 0, newlines = 0;
+
+    for (input = xmlctx->in->current; *input; ++input, ++parsed) {
+        if (*input != *delim) {
+            if (*input == '\n') {
+                ++newlines;
+            }
+            continue;
+        }
+        a = input;
+        b = delim;
+        for (i = 0; i < delim_len; ++i) {
+            if (*a++ != *b++) {
+                break;
+            }
+        }
+        if (i == delim_len) {
+            /* delim found */
+            xmlctx->in->line += newlines;
+            ly_in_skip(xmlctx->in, parsed + delim_len);
+            return LY_SUCCESS;
+        }
+    }
+
+    /* delim not found,
+     * do not update input handler to refer to the beginning of the section in error message */
+    LOGVAL(xmlctx->ctx, LY_VCODE_NTERM, sectname);
+    return LY_EVALID;
+}
+
+/**
+ * @brief Check/Get an XML identifier from the input string.
+ *
+ * The identifier must have at least one valid character complying the name start character constraints.
+ * The identifier is terminated by the first character, which does not comply to the name character constraints.
+ *
+ * See https://www.w3.org/TR/xml-names/#NT-NCName
+ *
+ * @param[in] xmlctx XML context.
+ * @param[out] start Pointer to the start of the identifier.
+ * @param[out] end Pointer ot the end of the identifier.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_parse_identifier(struct lyxml_ctx *xmlctx, const char **start, const char **end)
+{
+    const char *s, *in;
+    uint32_t c;
+    size_t parsed;
+    LY_ERR rc;
+
+    in = s = xmlctx->in->current;
+
+    /* check NameStartChar (minus colon) */
+    LY_CHECK_ERR_RET(ly_getutf8(&in, &c, &parsed),
+            LOGVAL(xmlctx->ctx, LY_VCODE_INCHAR, in[0]),
+            LY_EVALID);
+    LY_CHECK_ERR_RET(!is_xmlqnamestartchar(c),
+            LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Identifier \"%s\" starts with an invalid character.", in - parsed),
+            LY_EVALID);
+
+    /* check rest of the identifier */
+    do {
+        /* move only successfully parsed bytes */
+        ly_in_skip(xmlctx->in, parsed);
+
+        rc = ly_getutf8(&in, &c, &parsed);
+        LY_CHECK_ERR_RET(rc, LOGVAL(xmlctx->ctx, LY_VCODE_INCHAR, in[0]), LY_EVALID);
+    } while (is_xmlqnamechar(c));
+
+    *start = s;
+    *end = xmlctx->in->current;
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Add namespace definition into XML context.
+ *
+ * Namespaces from a single element are supposed to be added sequentially together (not interleaved by a namespace from other
+ * element). This mimic namespace visibility, since the namespace defined in element E is not visible from its parents or
+ * siblings. On the other hand, namespace from a parent element can be redefined in a child element. This is also reflected
+ * by lyxml_ns_get() which returns the most recent namespace definition for the given prefix.
+ *
+ * When leaving processing of a subtree of some element (after it is removed from xmlctx->elements), caller is supposed to call
+ * lyxml_ns_rm() to remove all the namespaces defined in such an element from the context.
+ *
+ * @param[in] xmlctx XML context to work with.
+ * @param[in] prefix Pointer to the namespace prefix. Can be NULL for default namespace.
+ * @param[in] prefix_len Length of the prefix.
+ * @param[in] uri Namespace URI (value) to store directly. Value is always spent.
+ * @return LY_ERR values.
+ */
+LY_ERR
+lyxml_ns_add(struct lyxml_ctx *xmlctx, const char *prefix, size_t prefix_len, char *uri)
+{
+    LY_ERR rc = LY_SUCCESS;
+    struct lyxml_ns *ns;
+    uint32_t i;
+
+    /* check for duplicates */
+    if (xmlctx->ns.count) {
+        i = xmlctx->ns.count;
+        do {
+            --i;
+            ns = xmlctx->ns.objs[i];
+            if (ns->depth < xmlctx->elements.count) {
+                /* only namespaces of parents, no need to check further */
+                break;
+            } else if (prefix && ns->prefix && !ly_strncmp(ns->prefix, prefix, prefix_len)) {
+                if (!strcmp(ns->uri, uri)) {
+                    /* exact same prefix and namespace, ignore */
+                    goto cleanup;
+                }
+
+                LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Duplicate XML NS prefix \"%s\" used for namespaces \"%s\" and \"%s\".",
+                        ns->prefix, ns->uri, uri);
+                rc = LY_EVALID;
+                goto cleanup;
+            } else if (!prefix && !ns->prefix) {
+                if (!strcmp(ns->uri, uri)) {
+                    /* exact same default namespace, ignore */
+                    goto cleanup;
+                }
+
+                LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Duplicate default XML namespaces \"%s\" and \"%s\".", ns->uri, uri);
+                rc = LY_EVALID;
+                goto cleanup;
+            }
+        } while (i);
+    }
+
+    ns = malloc(sizeof *ns);
+    LY_CHECK_ERR_GOTO(!ns, LOGMEM(xmlctx->ctx); rc = LY_EMEM, cleanup);
+
+    /* we need to connect the depth of the element where the namespace is defined with the
+     * namespace record to be able to maintain (remove) the record when the parser leaves
+     * (to its sibling or back to the parent) the element where the namespace was defined */
+    ns->depth = xmlctx->elements.count;
+
+    ns->uri = uri;
+    if (prefix) {
+        ns->prefix = strndup(prefix, prefix_len);
+        LY_CHECK_ERR_GOTO(!ns->prefix, LOGMEM(xmlctx->ctx); free(ns); rc = LY_EMEM, cleanup);
+    } else {
+        ns->prefix = NULL;
+    }
+
+    rc = ly_set_add(&xmlctx->ns, ns, 1, NULL);
+    LY_CHECK_ERR_GOTO(rc, free(ns->prefix); free(ns), cleanup);
+
+    /* successfully stored */
+    uri = NULL;
+
+cleanup:
+    free(uri);
+    return rc;
+}
+
+void
+lyxml_ns_rm(struct lyxml_ctx *xmlctx)
+{
+    for (uint32_t u = xmlctx->ns.count - 1; u + 1 > 0; --u) {
+        if (((struct lyxml_ns *)xmlctx->ns.objs[u])->depth != xmlctx->elements.count + 1) {
+            /* we are done, the namespaces from a single element are supposed to be together */
+            break;
+        }
+        /* remove the ns structure */
+        free(((struct lyxml_ns *)xmlctx->ns.objs[u])->prefix);
+        free(((struct lyxml_ns *)xmlctx->ns.objs[u])->uri);
+        free(xmlctx->ns.objs[u]);
+        --xmlctx->ns.count;
+    }
+
+    if (!xmlctx->ns.count) {
+        /* cleanup the xmlctx's namespaces storage */
+        ly_set_erase(&xmlctx->ns, NULL);
+    }
+}
+
+const struct lyxml_ns *
+lyxml_ns_get(const struct ly_set *ns_set, const char *prefix, size_t prefix_len)
+{
+    struct lyxml_ns *ns;
+
+    for (uint32_t u = ns_set->count - 1; u + 1 > 0; --u) {
+        ns = (struct lyxml_ns *)ns_set->objs[u];
+        if (prefix && prefix_len) {
+            if (ns->prefix && !ly_strncmp(ns->prefix, prefix, prefix_len)) {
+                return ns;
+            }
+        } else if (!ns->prefix) {
+            /* default namespace */
+            return ns;
+        }
+    }
+
+    return NULL;
+}
+
+/**
+ * @brief Skip in the input until EOF or just after the opening tag.
+ * Handles special XML constructs (comment, cdata, doctype).
+ *
+ * @param[in] xmlctx XML context to use.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_skip_until_end_or_after_otag(struct lyxml_ctx *xmlctx)
+{
+    const struct ly_ctx *ctx = xmlctx->ctx; /* shortcut */
+    const char *endtag, *sectname;
+    size_t endtag_len;
+
+    while (1) {
+        ign_xmlws(xmlctx);
+
+        if (xmlctx->in->current[0] == '\0') {
+            /* EOF */
+            if (xmlctx->elements.count) {
+                LOGVAL(ctx, LY_VCODE_EOF);
+                return LY_EVALID;
+            }
+            return LY_SUCCESS;
+        } else if (xmlctx->in->current[0] != '<') {
+            LOGVAL(ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(xmlctx->in->current), xmlctx->in->current,
+                    "element tag start ('<')");
+            return LY_EVALID;
+        }
+        move_input(xmlctx, 1);
+
+        if (xmlctx->in->current[0] == '!') {
+            move_input(xmlctx, 1);
+            /* sections to ignore */
+            if (!strncmp(xmlctx->in->current, "--", 2)) {
+                /* comment */
+                move_input(xmlctx, 2);
+                sectname = "Comment";
+                endtag = "-->";
+                endtag_len = ly_strlen_const("-->");
+            } else if (!strncmp(xmlctx->in->current, "DOCTYPE", ly_strlen_const("DOCTYPE"))) {
+                /* Document type declaration - not supported */
+                LOGVAL(ctx, LY_VCODE_NSUPP, "Document Type Declaration");
+                return LY_EVALID;
+            } else {
+                LOGVAL(ctx, LYVE_SYNTAX, "Unknown XML section \"%.20s\".", &xmlctx->in->current[-2]);
+                return LY_EVALID;
+            }
+            LY_CHECK_RET(skip_section(xmlctx, endtag, endtag_len, sectname));
+        } else if (xmlctx->in->current[0] == '?') {
+            LY_CHECK_RET(skip_section(xmlctx, "?>", 2, "Declaration"));
+        } else {
+            /* other non-WS character */
+            break;
+        }
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Parse QName.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[out] prefix Parsed prefix, may be NULL.
+ * @param[out] prefix_len Length of @p prefix.
+ * @param[out] name Parsed name.
+ * @param[out] name_len Length of @p name.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_parse_qname(struct lyxml_ctx *xmlctx, const char **prefix, size_t *prefix_len, const char **name, size_t *name_len)
+{
+    const char *start, *end;
+
+    *prefix = NULL;
+    *prefix_len = 0;
+
+    LY_CHECK_RET(lyxml_parse_identifier(xmlctx, &start, &end));
+    if (end[0] == ':') {
+        /* we have prefixed identifier */
+        *prefix = start;
+        *prefix_len = end - start;
+
+        move_input(xmlctx, 1);
+        LY_CHECK_RET(lyxml_parse_identifier(xmlctx, &start, &end));
+    }
+
+    *name = start;
+    *name_len = end - start;
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Prepare buffer for new data.
+ *
+ * @param[in] ctx Context for logging.
+ * @param[in,out] in XML input data.
+ * @param[in,out] offset Current offset in @p in.
+ * @param[in] need_space Needed additional free space that is allocated.
+ * @param[in,out] buf Dynamic buffer.
+ * @param[in,out] len Current @p buf length (used characters).
+ * @param[in,out] size Current @p buf size (allocated characters).
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_parse_value_use_buf(const struct ly_ctx *ctx, const char **in, size_t *offset, size_t need_space, char **buf,
+        size_t *len, size_t *size)
+{
+#define BUFSIZE 24
+#define BUFSIZE_STEP 128
+
+    if (!*buf) {
+        /* prepare output buffer */
+        *buf = malloc(BUFSIZE);
+        LY_CHECK_ERR_RET(!*buf, LOGMEM(ctx), LY_EMEM);
+        *size = BUFSIZE;
+    }
+
+    /* allocate needed space */
+    while (*len + *offset + need_space >= *size) {
+        *buf = ly_realloc(*buf, *size + BUFSIZE_STEP);
+        LY_CHECK_ERR_RET(!*buf, LOGMEM(ctx), LY_EMEM);
+        *size += BUFSIZE_STEP;
+    }
+
+    if (*offset) {
+        /* store what we have so far */
+        memcpy(&(*buf)[*len], *in, *offset);
+        *len += *offset;
+        *in += *offset;
+        *offset = 0;
+    }
+
+    return LY_SUCCESS;
+
+#undef BUFSIZE
+#undef BUFSIZE_STEP
+}
+
+/**
+ * @brief Parse XML text content (value).
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[in] endchar Expected character to mark value end.
+ * @param[out] value Parsed value.
+ * @param[out] length Length of @p value.
+ * @param[out] ws_only Whether the value is empty/white-spaces only.
+ * @param[out] dynamic Whether the value was dynamically allocated.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_parse_value(struct lyxml_ctx *xmlctx, char endchar, char **value, size_t *length, ly_bool *ws_only, ly_bool *dynamic)
+{
+    const struct ly_ctx *ctx = xmlctx->ctx; /* shortcut */
+    const char *in = xmlctx->in->current, *start, *in_aux;
+    char *buf = NULL;
+    size_t offset;   /* read offset in input buffer */
+    size_t len;      /* length of the output string (write offset in output buffer) */
+    size_t size = 0; /* size of the output buffer */
+    void *p;
+    uint32_t n;
+    size_t u;
+    ly_bool ws = 1;
+
+    assert(xmlctx);
+
+    /* init */
+    start = in;
+    offset = len = 0;
+
+    /* parse */
+    while (in[offset]) {
+        if (in[offset] == '&') {
+            /* non WS */
+            ws = 0;
+
+            /* use buffer and allocate enough for the offset and next character,
+             * we will need 4 bytes at most since we support only the predefined
+             * (one-char) entities and character references */
+            LY_CHECK_RET(lyxml_parse_value_use_buf(ctx, &in, &offset, 4, &buf, &len, &size));
+
+            ++offset;
+            if (in[offset] != '#') {
+                /* entity reference - only predefined references are supported */
+                if (!strncmp(&in[offset], "lt;", ly_strlen_const("lt;"))) {
+                    buf[len++] = '<';
+                    in += ly_strlen_const("&lt;");
+                } else if (!strncmp(&in[offset], "gt;", ly_strlen_const("gt;"))) {
+                    buf[len++] = '>';
+                    in += ly_strlen_const("&gt;");
+                } else if (!strncmp(&in[offset], "amp;", ly_strlen_const("amp;"))) {
+                    buf[len++] = '&';
+                    in += ly_strlen_const("&amp;");
+                } else if (!strncmp(&in[offset], "apos;", ly_strlen_const("apos;"))) {
+                    buf[len++] = '\'';
+                    in += ly_strlen_const("&apos;");
+                } else if (!strncmp(&in[offset], "quot;", ly_strlen_const("quot;"))) {
+                    buf[len++] = '\"';
+                    in += ly_strlen_const("&quot;");
+                } else {
+                    LOGVAL(ctx, LYVE_SYNTAX, "Entity reference \"%.*s\" not supported, only predefined references allowed.",
+                            10, &in[offset - 1]);
+                    goto error;
+                }
+                offset = 0;
+            } else {
+                p = (void *)&in[offset - 1];
+                /* character reference */
+                ++offset;
+                if (isdigit(in[offset])) {
+                    for (n = 0; isdigit(in[offset]); offset++) {
+                        n = (LY_BASE_DEC * n) + (in[offset] - '0');
+                    }
+                } else if ((in[offset] == 'x') && isxdigit(in[offset + 1])) {
+                    for (n = 0, ++offset; isxdigit(in[offset]); offset++) {
+                        if (isdigit(in[offset])) {
+                            u = (in[offset] - '0');
+                        } else if (in[offset] > 'F') {
+                            u = LY_BASE_DEC + (in[offset] - 'a');
+                        } else {
+                            u = LY_BASE_DEC + (in[offset] - 'A');
+                        }
+                        n = (LY_BASE_HEX * n) + u;
+                    }
+                } else {
+                    LOGVAL(ctx, LYVE_SYNTAX, "Invalid character reference \"%.*s\".", 12, p);
+                    goto error;
+
+                }
+
+                if (in[offset] != ';') {
+                    LOGVAL(ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(&in[offset]), &in[offset], ";");
+                    goto error;
+                }
+                ++offset;
+                if (ly_pututf8(&buf[len], n, &u)) {
+                    LOGVAL(ctx, LYVE_SYNTAX, "Invalid character reference \"%.*s\" (0x%08x).", 12, p, n);
+                    goto error;
+                }
+                len += u;
+                in += offset;
+                offset = 0;
+            }
+        } else if (!strncmp(in + offset, "<![CDATA[", ly_strlen_const("<![CDATA["))) {
+            /* CDATA, find the end */
+            in_aux = strstr(in + offset + ly_strlen_const("<![CDATA["), "]]>");
+            if (!in_aux) {
+                LOGVAL(xmlctx->ctx, LY_VCODE_NTERM, "CDATA");
+                goto error;
+            }
+            u = in_aux - (in + offset + ly_strlen_const("<![CDATA["));
+
+            /* use buffer, allocate enough for the whole CDATA */
+            LY_CHECK_RET(lyxml_parse_value_use_buf(ctx, &in, &offset, u, &buf, &len, &size));
+
+            /* skip CDATA tag */
+            in += ly_strlen_const("<![CDATA[");
+            assert(!offset);
+
+            /* analyze CDATA for non WS and newline chars */
+            for (n = 0; n < u; ++n) {
+                if (in[n] == '\n') {
+                    LY_IN_NEW_LINE(xmlctx->in);
+                } else if (!is_xmlws(in[n])) {
+                    ws = 0;
+                }
+            }
+
+            /* copy CDATA */
+            memcpy(buf + len, in, u);
+            len += u;
+
+            /* move input skipping the end tag */
+            in += u + ly_strlen_const("]]>");
+        } else if (in[offset] == endchar) {
+            /* end of string */
+            if (buf) {
+                /* realloc exact size string */
+                buf = ly_realloc(buf, len + offset + 1);
+                LY_CHECK_ERR_RET(!buf, LOGMEM(ctx), LY_EMEM);
+                size = len + offset + 1;
+                if (offset) {
+                    memcpy(&buf[len], in, offset);
+                }
+
+                /* set terminating NULL byte */
+                buf[len + offset] = '\0';
+            }
+            len += offset;
+            in += offset;
+            goto success;
+        } else {
+            if (!is_xmlws(in[offset])) {
+                /* non WS */
+                ws = 0;
+            }
+
+            /* log lines */
+            if (in[offset] == '\n') {
+                LY_IN_NEW_LINE(xmlctx->in);
+            }
+
+            /* continue */
+            in_aux = &in[offset];
+            LY_CHECK_ERR_GOTO(ly_getutf8(&in_aux, &n, &u),
+                    LOGVAL(ctx, LY_VCODE_INCHAR, in[offset]), error);
+            offset += u;
+        }
+    }
+
+    /* EOF reached before endchar */
+    LOGVAL(ctx, LY_VCODE_EOF);
+
+error:
+    free(buf);
+    return LY_EVALID;
+
+success:
+    if (buf) {
+        *value = buf;
+        *dynamic = 1;
+    } else {
+        *value = (char *)start;
+        *dynamic = 0;
+    }
+    *length = len;
+    *ws_only = ws;
+
+    xmlctx->in->current = in;
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Parse XML closing element and match it to a stored starting element.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[in] prefix Expected closing element prefix.
+ * @param[in] prefix_len Length of @p prefix.
+ * @param[in] name Expected closing element name.
+ * @param[in] name_len Length of @p name.
+ * @param[in] empty Whether we are parsing a special "empty" element (with joined starting and closing tag) with no value.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_close_element(struct lyxml_ctx *xmlctx, const char *prefix, size_t prefix_len, const char *name, size_t name_len,
+        ly_bool empty)
+{
+    struct lyxml_elem *e;
+
+    /* match opening and closing element tags */
+    if (!xmlctx->elements.count) {
+        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Stray closing element tag (\"%.*s\").",
+                (int)name_len, name);
+        return LY_EVALID;
+    }
+
+    e = (struct lyxml_elem *)xmlctx->elements.objs[xmlctx->elements.count - 1];
+    if ((e->prefix_len != prefix_len) || (e->name_len != name_len) ||
+            (prefix_len && strncmp(prefix, e->prefix, e->prefix_len)) || strncmp(name, e->name, e->name_len)) {
+        LOGVAL(xmlctx->ctx, LYVE_SYNTAX, "Opening (\"%.*s%s%.*s\") and closing (\"%.*s%s%.*s\") elements tag mismatch.",
+                (int)e->prefix_len, e->prefix ? e->prefix : "", e->prefix ? ":" : "", (int)e->name_len, e->name,
+                (int)prefix_len, prefix ? prefix : "", prefix ? ":" : "", (int)name_len, name);
+        return LY_EVALID;
+    }
+
+    /* opening and closing element tags matches, remove record from the opening tags list */
+    ly_set_rm_index(&xmlctx->elements, xmlctx->elements.count - 1, free);
+
+    /* remove also the namespaces connected with the element */
+    lyxml_ns_rm(xmlctx);
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* special "<elem/>" element */
+    if (empty && (xmlctx->in->current[0] == '/')) {
+        move_input(xmlctx, 1);
+    }
+
+    /* parse closing tag */
+    if (xmlctx->in->current[0] != '>') {
+        LOGVAL(xmlctx->ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(xmlctx->in->current),
+                xmlctx->in->current, "element tag termination ('>')");
+        return LY_EVALID;
+    }
+
+    /* move after closing tag without checking for EOF */
+    ly_in_skip(xmlctx->in, 1);
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Store parsed opening element and parse any included namespaces.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[in] prefix Parsed starting element prefix.
+ * @param[in] prefix_len Length of @p prefix.
+ * @param[in] name Parsed starting element name.
+ * @param[in] name_len Length of @p name.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_open_element(struct lyxml_ctx *xmlctx, const char *prefix, size_t prefix_len, const char *name, size_t name_len)
+{
+    LY_ERR ret = LY_SUCCESS;
+    struct lyxml_elem *e;
+    const char *prev_input;
+    uint64_t prev_line;
+    char *value;
+    size_t parsed, value_len;
+    ly_bool ws_only, dynamic, is_ns;
+    uint32_t c;
+
+    /* store element opening tag information */
+    e = malloc(sizeof *e);
+    LY_CHECK_ERR_RET(!e, LOGMEM(xmlctx->ctx), LY_EMEM);
+    e->name = name;
+    e->prefix = prefix;
+    e->name_len = name_len;
+    e->prefix_len = prefix_len;
+
+    LY_CHECK_RET(ly_set_add(&xmlctx->elements, e, 1, NULL));
+    if (xmlctx->elements.count > LY_MAX_BLOCK_DEPTH) {
+        LOGERR(xmlctx->ctx, LY_EINVAL, "The maximum number of open elements has been exceeded.");
+        return LY_EINVAL;
+    }
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* parse and store all namespaces */
+    prev_input = xmlctx->in->current;
+    prev_line = xmlctx->in->line;
+    is_ns = 1;
+    while ((xmlctx->in->current[0] != '\0') && !(ret = ly_getutf8(&xmlctx->in->current, &c, &parsed))) {
+        if (!is_xmlqnamestartchar(c)) {
+            break;
+        }
+        xmlctx->in->current -= parsed;
+
+        /* parse attribute name */
+        LY_CHECK_GOTO(ret = lyxml_parse_qname(xmlctx, &prefix, &prefix_len, &name, &name_len), cleanup);
+
+        /* parse the value */
+        LY_CHECK_GOTO(ret = lyxml_next_attr_content(xmlctx, (const char **)&value, &value_len, &ws_only, &dynamic), cleanup);
+
+        /* store every namespace */
+        if ((prefix && !ly_strncmp("xmlns", prefix, prefix_len)) || (!prefix && !ly_strncmp("xmlns", name, name_len))) {
+            ret = lyxml_ns_add(xmlctx, prefix ? name : NULL, prefix ? name_len : 0,
+                    dynamic ? value : strndup(value, value_len));
+            dynamic = 0;
+            LY_CHECK_GOTO(ret, cleanup);
+        } else {
+            /* not a namespace */
+            is_ns = 0;
+        }
+        if (dynamic) {
+            free(value);
+        }
+
+        /* skip WS */
+        ign_xmlws(xmlctx);
+
+        if (is_ns) {
+            /* we can actually skip all the namespaces as there is no reason to parse them again */
+            prev_input = xmlctx->in->current;
+            prev_line = xmlctx->in->line;
+        }
+    }
+
+cleanup:
+    if (!ret) {
+        xmlctx->in->current = prev_input;
+        xmlctx->in->line = prev_line;
+    }
+    return ret;
+}
+
+/**
+ * @brief Move parser to the attribute content and parse it.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[out] value Parsed attribute value.
+ * @param[out] value_len Length of @p value.
+ * @param[out] ws_only Whether the value is empty/white-spaces only.
+ * @param[out] dynamic Whether the value was dynamically allocated.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_next_attr_content(struct lyxml_ctx *xmlctx, const char **value, size_t *value_len, ly_bool *ws_only, ly_bool *dynamic)
+{
+    char quot;
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* skip '=' */
+    if (xmlctx->in->current[0] == '\0') {
+        LOGVAL(xmlctx->ctx, LY_VCODE_EOF);
+        return LY_EVALID;
+    } else if (xmlctx->in->current[0] != '=') {
+        LOGVAL(xmlctx->ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(xmlctx->in->current),
+                xmlctx->in->current, "'='");
+        return LY_EVALID;
+    }
+    move_input(xmlctx, 1);
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* find quotes */
+    if (xmlctx->in->current[0] == '\0') {
+        LOGVAL(xmlctx->ctx, LY_VCODE_EOF);
+        return LY_EVALID;
+    } else if ((xmlctx->in->current[0] != '\'') && (xmlctx->in->current[0] != '\"')) {
+        LOGVAL(xmlctx->ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(xmlctx->in->current),
+                xmlctx->in->current, "either single or double quotation mark");
+        return LY_EVALID;
+    }
+
+    /* remember quote */
+    quot = xmlctx->in->current[0];
+    move_input(xmlctx, 1);
+
+    /* parse attribute value */
+    LY_CHECK_RET(lyxml_parse_value(xmlctx, quot, (char **)value, value_len, ws_only, dynamic));
+
+    /* move after ending quote (without checking for EOF) */
+    ly_in_skip(xmlctx->in, 1);
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Move parser to the next attribute and parse it.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[out] prefix Parsed attribute prefix.
+ * @param[out] prefix_len Length of @p prefix.
+ * @param[out] name Parsed attribute name.
+ * @param[out] name_len Length of @p name.
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_next_attribute(struct lyxml_ctx *xmlctx, const char **prefix, size_t *prefix_len, const char **name, size_t *name_len)
+{
+    const char *in;
+    char *value;
+    uint32_t c;
+    size_t parsed, value_len;
+    ly_bool ws_only, dynamic;
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* parse only possible attributes */
+    while ((xmlctx->in->current[0] != '>') && (xmlctx->in->current[0] != '/')) {
+        in = xmlctx->in->current;
+        if (in[0] == '\0') {
+            LOGVAL(xmlctx->ctx, LY_VCODE_EOF);
+            return LY_EVALID;
+        } else if ((ly_getutf8(&in, &c, &parsed) || !is_xmlqnamestartchar(c))) {
+            LOGVAL(xmlctx->ctx, LY_VCODE_INSTREXP, LY_VCODE_INSTREXP_len(in - parsed), in - parsed,
+                    "element tag end ('>' or '/>') or an attribute");
+            return LY_EVALID;
+        }
+
+        /* parse attribute name */
+        LY_CHECK_RET(lyxml_parse_qname(xmlctx, prefix, prefix_len, name, name_len));
+
+        if ((!*prefix || ly_strncmp("xmlns", *prefix, *prefix_len)) && (*prefix || ly_strncmp("xmlns", *name, *name_len))) {
+            /* standard attribute */
+            break;
+        }
+
+        /* namespace, skip it */
+        LY_CHECK_RET(lyxml_next_attr_content(xmlctx, (const char **)&value, &value_len, &ws_only, &dynamic));
+        if (dynamic) {
+            free(value);
+        }
+
+        /* skip WS */
+        ign_xmlws(xmlctx);
+    }
+
+    return LY_SUCCESS;
+}
+
+/**
+ * @brief Move parser to the next element and parse it.
+ *
+ * @param[in] xmlctx XML context to use.
+ * @param[out] prefix Parsed element prefix.
+ * @param[out] prefix_len Length of @p prefix.
+ * @param[out] name Parse element name.
+ * @param[out] name_len Length of @p name.
+ * @param[out] closing Flag if the element is closing (includes '/').
+ * @return LY_ERR value.
+ */
+static LY_ERR
+lyxml_next_element(struct lyxml_ctx *xmlctx, const char **prefix, size_t *prefix_len, const char **name, size_t *name_len,
+        ly_bool *closing)
+{
+    /* skip WS until EOF or after opening tag '<' */
+    LY_CHECK_RET(lyxml_skip_until_end_or_after_otag(xmlctx));
+    if (xmlctx->in->current[0] == '\0') {
+        /* set return values */
+        *prefix = *name = NULL;
+        *prefix_len = *name_len = 0;
+        return LY_SUCCESS;
+    }
+
+    if (xmlctx->in->current[0] == '/') {
+        move_input(xmlctx, 1);
+        *closing = 1;
+    } else {
+        *closing = 0;
+    }
+
+    /* skip WS */
+    ign_xmlws(xmlctx);
+
+    /* parse element name */
+    LY_CHECK_RET(lyxml_parse_qname(xmlctx, prefix, prefix_len, name, name_len));
+
+    return LY_SUCCESS;
+}
+
+LY_ERR
+lyxml_ctx_new(const struct ly_ctx *ctx, struct ly_in *in, struct lyxml_ctx **xmlctx_p)
+{
+    LY_ERR ret = LY_SUCCESS;
+    struct lyxml_ctx *xmlctx;
+    ly_bool closing;
+
+    /* new context */
+    xmlctx = calloc(1, sizeof *xmlctx);
+    LY_CHECK_ERR_RET(!xmlctx, LOGMEM(ctx), LY_EMEM);
+    xmlctx->ctx = ctx;
+    xmlctx->in = in;
+
+    LOG_LOCSET(NULL, NULL, NULL, in);
+
+    /* parse next element, if any */
+    LY_CHECK_GOTO(ret = lyxml_next_element(xmlctx, &xmlctx->prefix, &xmlctx->prefix_len, &xmlctx->name,
+            &xmlctx->name_len, &closing), cleanup);
+
+    if (xmlctx->in->current[0] == '\0') {
+        /* update status */
+        xmlctx->status = LYXML_END;
+    } else if (closing) {
+        LOGVAL(ctx, LYVE_SYNTAX, "Stray closing element tag (\"%.*s\").", (int)xmlctx->name_len, xmlctx->name);
+        ret = LY_EVALID;
+        goto cleanup;
+    } else {
+        /* open an element, also parses all enclosed namespaces */
+        LY_CHECK_GOTO(ret = lyxml_open_element(xmlctx, xmlctx->prefix, xmlctx->prefix_len, xmlctx->name, xmlctx->name_len), cleanup);
+
+        /* update status */
+        xmlctx->status = LYXML_ELEMENT;
+    }
+
+cleanup:
+    if (ret) {
+        lyxml_ctx_free(xmlctx);
+    } else {
+        *xmlctx_p = xmlctx;
+    }
+    return ret;
+}
+
+LY_ERR
+lyxml_ctx_next(struct lyxml_ctx *xmlctx)
+{
+    LY_ERR ret = LY_SUCCESS;
+    ly_bool closing;
+    struct lyxml_elem *e;
+
+    /* if the value was not used, free it */
+    if (((xmlctx->status == LYXML_ELEM_CONTENT) || (xmlctx->status == LYXML_ATTR_CONTENT)) && xmlctx->dynamic) {
+        free((char *)xmlctx->value);
+        xmlctx->value = NULL;
+        xmlctx->dynamic = 0;
+    }
+
+    switch (xmlctx->status) {
+    case LYXML_ELEM_CONTENT:
+        /* content |</elem> */
+
+        /* handle special case when empty content for "<elem/>" was returned */
+        if (xmlctx->in->current[0] == '/') {
+            assert(xmlctx->elements.count);
+            e = (struct lyxml_elem *)xmlctx->elements.objs[xmlctx->elements.count - 1];
+
+            /* close the element (parses closing tag) */
+            ret = lyxml_close_element(xmlctx, e->prefix, e->prefix_len, e->name, e->name_len, 1);
+            LY_CHECK_GOTO(ret, cleanup);
+
+            /* update status */
+            xmlctx->status = LYXML_ELEM_CLOSE;
+            break;
+        }
+    /* fall through */
+    case LYXML_ELEM_CLOSE:
+        /* </elem>| <elem2>* */
+
+        /* parse next element, if any */
+        ret = lyxml_next_element(xmlctx, &xmlctx->prefix, &xmlctx->prefix_len, &xmlctx->name, &xmlctx->name_len, &closing);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        if (xmlctx->in->current[0] == '\0') {
+            /* update status */
+            xmlctx->status = LYXML_END;
+        } else if (closing) {
+            /* close an element (parses also closing tag) */
+            ret = lyxml_close_element(xmlctx, xmlctx->prefix, xmlctx->prefix_len, xmlctx->name, xmlctx->name_len, 0);
+            LY_CHECK_GOTO(ret, cleanup);
+
+            /* update status */
+            xmlctx->status = LYXML_ELEM_CLOSE;
+        } else {
+            /* open an element, also parses all enclosed namespaces */
+            ret = lyxml_open_element(xmlctx, xmlctx->prefix, xmlctx->prefix_len, xmlctx->name, xmlctx->name_len);
+            LY_CHECK_GOTO(ret, cleanup);
+
+            /* update status */
+            xmlctx->status = LYXML_ELEMENT;
+        }
+        break;
+
+    case LYXML_ELEMENT:
+    /* <elem| attr='val'* > content  */
+    case LYXML_ATTR_CONTENT:
+        /* attr='val'| attr='val'* > content */
+
+        /* parse attribute name, if any */
+        ret = lyxml_next_attribute(xmlctx, &xmlctx->prefix, &xmlctx->prefix_len, &xmlctx->name, &xmlctx->name_len);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        if (xmlctx->in->current[0] == '>') {
+            /* no attributes but a closing tag */
+            ly_in_skip(xmlctx->in, 1);
+            if (!xmlctx->in->current[0]) {
+                LOGVAL(xmlctx->ctx, LY_VCODE_EOF);
+                ret = LY_EVALID;
+                goto cleanup;
+            }
+
+            /* parse element content */
+            ret = lyxml_parse_value(xmlctx, '<', (char **)&xmlctx->value, &xmlctx->value_len, &xmlctx->ws_only,
+                    &xmlctx->dynamic);
+            LY_CHECK_GOTO(ret, cleanup);
+
+            if (!xmlctx->value_len) {
+                /* empty value should by alocated staticaly, but check for in any case */
+                if (xmlctx->dynamic) {
+                    free((char *) xmlctx->value);
+                }
+                /* use empty value, easier to work with */
+                xmlctx->value = "";
+                xmlctx->dynamic = 0;
+            }
+
+            /* update status */
+            xmlctx->status = LYXML_ELEM_CONTENT;
+        } else if (xmlctx->in->current[0] == '/') {
+            /* no content but we still return it */
+            xmlctx->value = "";
+            xmlctx->value_len = 0;
+            xmlctx->ws_only = 1;
+            xmlctx->dynamic = 0;
+
+            /* update status */
+            xmlctx->status = LYXML_ELEM_CONTENT;
+        } else {
+            /* update status */
+            xmlctx->status = LYXML_ATTRIBUTE;
+        }
+        break;
+
+    case LYXML_ATTRIBUTE:
+        /* attr|='val' */
+
+        /* skip formatting and parse value */
+        ret = lyxml_next_attr_content(xmlctx, &xmlctx->value, &xmlctx->value_len, &xmlctx->ws_only, &xmlctx->dynamic);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        /* update status */
+        xmlctx->status = LYXML_ATTR_CONTENT;
+        break;
+
+    case LYXML_END:
+        /* </elem>   |EOF */
+        /* nothing to do */
+        break;
+    }
+
+cleanup:
+    if (ret) {
+        /* invalidate context */
+        xmlctx->status = LYXML_END;
+    }
+    return ret;
+}
+
+LY_ERR
+lyxml_ctx_peek(struct lyxml_ctx *xmlctx, enum LYXML_PARSER_STATUS *next)
+{
+    LY_ERR ret = LY_SUCCESS;
+    const char *prefix, *name, *prev_input;
+    size_t prefix_len, name_len;
+    ly_bool closing;
+
+    prev_input = xmlctx->in->current;
+
+    switch (xmlctx->status) {
+    case LYXML_ELEM_CONTENT:
+        if (xmlctx->in->current[0] == '/') {
+            *next = LYXML_ELEM_CLOSE;
+            break;
+        }
+    /* fall through */
+    case LYXML_ELEM_CLOSE:
+        /* parse next element, if any */
+        ret = lyxml_next_element(xmlctx, &prefix, &prefix_len, &name, &name_len, &closing);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        if (xmlctx->in->current[0] == '\0') {
+            *next = LYXML_END;
+        } else if (closing) {
+            *next = LYXML_ELEM_CLOSE;
+        } else {
+            *next = LYXML_ELEMENT;
+        }
+        break;
+    case LYXML_ELEMENT:
+    case LYXML_ATTR_CONTENT:
+        /* parse attribute name, if any */
+        ret = lyxml_next_attribute(xmlctx, &prefix, &prefix_len, &name, &name_len);
+        LY_CHECK_GOTO(ret, cleanup);
+
+        if ((xmlctx->in->current[0] == '>') || (xmlctx->in->current[0] == '/')) {
+            *next = LYXML_ELEM_CONTENT;
+        } else {
+            *next = LYXML_ATTRIBUTE;
+        }
+        break;
+    case LYXML_ATTRIBUTE:
+        *next = LYXML_ATTR_CONTENT;
+        break;
+    case LYXML_END:
+        *next = LYXML_END;
+        break;
+    }
+
+cleanup:
+    xmlctx->in->current = prev_input;
+    return ret;
+}
+
+/**
+ * @brief Free all namespaces in XML context.
+ *
+ * @param[in] xmlctx XML context to use.
+ */
+static void
+lyxml_ns_rm_all(struct lyxml_ctx *xmlctx)
+{
+    struct lyxml_ns *ns;
+    uint32_t i;
+
+    for (i = 0; i < xmlctx->ns.count; ++i) {
+        ns = xmlctx->ns.objs[i];
+
+        free(ns->prefix);
+        free(ns->uri);
+        free(ns);
+    }
+    ly_set_erase(&xmlctx->ns, NULL);
+}
+
+void
+lyxml_ctx_free(struct lyxml_ctx *xmlctx)
+{
+    if (!xmlctx) {
+        return;
+    }
+
+    LOG_LOCBACK(0, 0, 0, 1);
+
+    if (((xmlctx->status == LYXML_ELEM_CONTENT) || (xmlctx->status == LYXML_ATTR_CONTENT)) && xmlctx->dynamic) {
+        free((char *)xmlctx->value);
+    }
+    ly_set_erase(&xmlctx->elements, free);
+    lyxml_ns_rm_all(xmlctx);
+    free(xmlctx);
+}
+
+/**
+ * @brief Duplicate an XML element.
+ *
+ * @param[in] elem Element to duplicate.
+ * @return Element duplicate.
+ * @return NULL on error.
+ */
+static struct lyxml_elem *
+lyxml_elem_dup(const struct lyxml_elem *elem)
+{
+    struct lyxml_elem *dup;
+
+    dup = malloc(sizeof *dup);
+    LY_CHECK_ERR_RET(!dup, LOGMEM(NULL), NULL);
+
+    memcpy(dup, elem, sizeof *dup);
+
+    return dup;
+}
+
+/**
+ * @brief Duplicate an XML namespace.
+ *
+ * @param[in] ns Namespace to duplicate.
+ * @return Namespace duplicate.
+ * @return NULL on error.
+ */
+static struct lyxml_ns *
+lyxml_ns_dup(const struct lyxml_ns *ns)
+{
+    struct lyxml_ns *dup;
+
+    dup = malloc(sizeof *dup);
+    LY_CHECK_ERR_RET(!dup, LOGMEM(NULL), NULL);
+
+    if (ns->prefix) {
+        dup->prefix = strdup(ns->prefix);
+        LY_CHECK_ERR_RET(!dup->prefix, LOGMEM(NULL); free(dup), NULL);
+    } else {
+        dup->prefix = NULL;
+    }
+    dup->uri = strdup(ns->uri);
+    LY_CHECK_ERR_RET(!dup->uri, LOGMEM(NULL); free(dup->prefix); free(dup), NULL);
+    dup->depth = ns->depth;
+
+    return dup;
+}
+
+LY_ERR
+lyxml_ctx_backup(struct lyxml_ctx *xmlctx, struct lyxml_ctx *backup)
+{
+    uint32_t i;
+
+    /* first make shallow copy */
+    memcpy(backup, xmlctx, sizeof *backup);
+
+    if ((xmlctx->status == LYXML_ELEM_CONTENT) && xmlctx->dynamic) {
+        /* it was backed up, do not free */
+        xmlctx->dynamic = 0;
+    }
+
+    /* backup in */
+    backup->b_current = xmlctx->in->current;
+    backup->b_line = xmlctx->in->line;
+
+    /* duplicate elements */
+    backup->elements.objs = malloc(xmlctx->elements.size * sizeof(struct lyxml_elem));
+    LY_CHECK_ERR_RET(!backup->elements.objs, LOGMEM(xmlctx->ctx), LY_EMEM);
+    for (i = 0; i < xmlctx->elements.count; ++i) {
+        backup->elements.objs[i] = lyxml_elem_dup(xmlctx->elements.objs[i]);
+        LY_CHECK_RET(!backup->elements.objs[i], LY_EMEM);
+    }
+
+    /* duplicate ns */
+    backup->ns.objs = malloc(xmlctx->ns.size * sizeof(struct lyxml_ns));
+    LY_CHECK_ERR_RET(!backup->ns.objs, LOGMEM(xmlctx->ctx), LY_EMEM);
+    for (i = 0; i < xmlctx->ns.count; ++i) {
+        backup->ns.objs[i] = lyxml_ns_dup(xmlctx->ns.objs[i]);
+        LY_CHECK_RET(!backup->ns.objs[i], LY_EMEM);
+    }
+
+    return LY_SUCCESS;
+}
+
+void
+lyxml_ctx_restore(struct lyxml_ctx *xmlctx, struct lyxml_ctx *backup)
+{
+    if (((xmlctx->status == LYXML_ELEM_CONTENT) || (xmlctx->status == LYXML_ATTR_CONTENT)) && xmlctx->dynamic) {
+        /* free dynamic value */
+        free((char *)xmlctx->value);
+    }
+
+    /* free elements */
+    ly_set_erase(&xmlctx->elements, free);
+
+    /* free ns */
+    lyxml_ns_rm_all(xmlctx);
+
+    /* restore in */
+    xmlctx->in->current = backup->b_current;
+    xmlctx->in->line = backup->b_line;
+    backup->in = xmlctx->in;
+
+    /* restore backup */
+    memcpy(xmlctx, backup, sizeof *xmlctx);
+}
+
+LY_ERR
+lyxml_dump_text(struct ly_out *out, const char *text, ly_bool attribute)
+{
+    LY_ERR ret;
+
+    if (!text) {
+        return 0;
+    }
+
+    for (uint64_t u = 0; text[u]; u++) {
+        switch (text[u]) {
+        case '&':
+            ret = ly_print_(out, "&amp;");
+            break;
+        case '<':
+            ret = ly_print_(out, "&lt;");
+            break;
+        case '>':
+            /* not needed, just for readability */
+            ret = ly_print_(out, "&gt;");
+            break;
+        case '"':
+            if (attribute) {
+                ret = ly_print_(out, "&quot;");
+                break;
+            }
+        /* fall through */
+        default:
+            ret = ly_write_(out, &text[u], 1);
+            break;
+        }
+        LY_CHECK_RET(ret);
+    }
+
+    return LY_SUCCESS;
+}
+
+LY_ERR
+lyxml_value_compare(const struct ly_ctx *ctx1, const char *value1, void *val_prefix_data1,
+        const struct ly_ctx *ctx2, const char *value2, void *val_prefix_data2)
+{
+    const char *value1_iter, *value2_iter;
+    const char *value1_next, *value2_next;
+    uint32_t value1_len, value2_len;
+    ly_bool is_prefix1, is_prefix2;
+    const struct lys_module *mod1, *mod2;
+    LY_ERR ret;
+
+    if (!value1 && !value2) {
+        return LY_SUCCESS;
+    }
+    if ((value1 && !value2) || (!value1 && value2)) {
+        return LY_ENOT;
+    }
+
+    if (!ctx2) {
+        ctx2 = ctx1;
+    }
+
+    ret = LY_SUCCESS;
+    for (value1_iter = value1, value2_iter = value2;
+            value1_iter && value2_iter;
+            value1_iter = value1_next, value2_iter = value2_next) {
+        if ((ret = ly_value_prefix_next(value1_iter, NULL, &value1_len, &is_prefix1, &value1_next))) {
+            break;
+        }
+        if ((ret = ly_value_prefix_next(value2_iter, NULL, &value2_len, &is_prefix2, &value2_next))) {
+            break;
+        }
+
+        if (is_prefix1 != is_prefix2) {
+            ret = LY_ENOT;
+            break;
+        }
+
+        if (!is_prefix1) {
+            if (value1_len != value2_len) {
+                ret = LY_ENOT;
+                break;
+            }
+            if (strncmp(value1_iter, value2_iter, value1_len)) {
+                ret = LY_ENOT;
+                break;
+            }
+            continue;
+        }
+
+        mod1 = mod2 = NULL;
+        if (val_prefix_data1) {
+            /* find module of the first prefix, if any */
+            mod1 = ly_resolve_prefix(ctx1, value1_iter, value1_len, LY_VALUE_XML, val_prefix_data1);
+        }
+        if (val_prefix_data2) {
+            mod2 = ly_resolve_prefix(ctx2, value2_iter, value2_len, LY_VALUE_XML, val_prefix_data2);
+        }
+        if (!mod1 || !mod2) {
+            /* not a prefix or maps to different namespaces */
+            ret = LY_ENOT;
+            break;
+        }
+
+        if (mod1->ctx == mod2->ctx) {
+            /* same contexts */
+            if ((mod1->name != mod2->name) || (mod1->revision != mod2->revision)) {
+                ret = LY_ENOT;
+                break;
+            }
+        } else {
+            /* different contexts */
+            if (strcmp(mod1->name, mod2->name)) {
+                ret = LY_ENOT;
+                break;
+            }
+
+            if (mod1->revision || mod2->revision) {
+                if (!mod1->revision || !mod2->revision) {
+                    ret = LY_ENOT;
+                    break;
+                }
+                if (strcmp(mod1->revision, mod2->revision)) {
+                    ret = LY_ENOT;
+                    break;
+                }
+            }
+        }
+    }
+
+    if (value1_iter || value2_iter) {
+        ret = LY_ENOT;
+    }
+
+    return ret;
+}