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clixon/lib/src/clixon_xpath.c
Olof hagsand 40d5b99d3b Reverted some of the nsc xpath API changes. In the revert, xpath_first() and xpath_vec() retain their old syntax with nsc==NULL. 
The reason is to be conservative with the API. However, less used functions, such as xpath_vec_bool(), xpath_vec_ctx() and xpath_vec_flag()  are changed with a new `nsc`parameter, which should be set to NULL in most cases.
2019-07-09 12:19:03 +02:00

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/*
*
***** BEGIN LICENSE BLOCK *****
Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren
This file is part of CLIXON.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
Alternatively, the contents of this file may be used under the terms of
the GNU General Public License Version 3 or later (the "GPL"),
in which case the provisions of the GPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of the GPL, and not to allow others to
use your version of this file under the terms of Apache License version 2, indicate
your decision by deleting the provisions above and replace them with the
notice and other provisions required by the GPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the Apache License version 2 or the GPL.
***** END LICENSE BLOCK *****
* Clixon XML XPATH 1.0 according to https://www.w3.org/TR/xpath-10
*
* Some notes on namespace extensions in Netconf/Yang
* RFC6241 8.9.1
* The set of namespace declarations are those in scope on the <filter> element.
* <rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
* <get-config>
* <filter xmlns:t="http://example.com/schema/1.2/config"
* type="xpath"
* select="/t:top/t:users/t:user[t:name='fred']"/>
* </get-config>
* We need to add namespace context to the cpath tree, typically in eval. How do
* we do that?
* One observation is that the namespace context is static, so it can not be a part
* of the xpath-tree, which is context-dependent.
* Best is to send it as a (read-only) parameter to the xp_eval family of functions
* as an exlicit namespace context.
* For that you need an API to get/set namespaces: clixon_xml_nscache.c?
* Then you need to fix API functions and this is the real work:
* - Replace all existing functions or create new?
* - Expose explicit namespace parameter, or xml object, or default namespace?
*
* @see README.md#xml-and-xpath for description of xpath implementation
*/
#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <limits.h>
#include <fnmatch.h>
#include <stdint.h>
#include <assert.h>
#include <syslog.h>
#include <fcntl.h>
#include <math.h>
/* cligen */
#include <cligen/cligen.h>
/* clicon */
#include "clixon_err.h"
#include "clixon_log.h"
#include "clixon_string.h"
#include "clixon_queue.h"
#include "clixon_hash.h"
#include "clixon_handle.h"
#include "clixon_yang.h"
#include "clixon_xml.h"
#include "clixon_xml_nsctx.h"
#include "clixon_xpath_ctx.h"
#include "clixon_xpath.h"
#include "clixon_xpath_parse.h"
#include "clixon_xpath_eval.h"
/*
* Variables
*/
/* Mapping between xpath_tree node name string <--> int */
static const map_str2int xpath_tree_map[] = {
{"expr", XP_EXP},
{"andexpr", XP_AND},
{"relexpr", XP_RELEX},
{"addexpr", XP_ADD},
{"unionexpr", XP_UNION},
{"pathexpr", XP_PATHEXPR},
{"locationpath", XP_LOCPATH},
{"abslocpath", XP_ABSPATH},
{"rellocpath", XP_RELLOCPATH},
{"step", XP_STEP},
{"nodetest", XP_NODE},
{"nodetest fn", XP_NODE_FN},
{"predicates", XP_PRED},
{"primaryexpr", XP_PRI0},
{"primaryexpr nr", XP_PRIME_NR},
{"primaryexpr str", XP_PRIME_STR},
{"primaryexpr fn", XP_PRIME_FN},
{NULL, -1}
};
/*
* XPATH parse tree type
*/
/*! Map from xpath_tree node name int to string
*/
char*
xpath_tree_int2str(int nodetype)
{
return (char*)clicon_int2str(xpath_tree_map, nodetype);
}
/*! Print XPATH parse tree */
static int
xpath_tree_print0(cbuf *cb,
xpath_tree *xs,
int level)
{
cprintf(cb, "%*s%s:", level*3, "", xpath_tree_int2str(xs->xs_type));
if (xs->xs_s0){
cprintf(cb, "\"%s\" ", xs->xs_s0);
if (xs->xs_s1)
cprintf(cb,"\"%s\" ", xs->xs_s1);
}
cprintf(cb, "\n");
if (xs->xs_c0)
xpath_tree_print0(cb, xs->xs_c0,level+1);
if (xs->xs_c1)
xpath_tree_print0(cb, xs->xs_c1, level+1);
return 0;
}
/*! Print a xpath_tree
* @param[out] cb CLIgen buffer
* @param[in] xs XPATH tree
*/
int
xpath_tree_print(cbuf *cb,
xpath_tree *xs)
{
xpath_tree_print0(cb, xs, 0);
return 0;
}
/*! Free a xpath_tree
* @param[in] xs XPATH tree
* @see xpath_parse creates a xpath_tree
*/
int
xpath_tree_free(xpath_tree *xs)
{
if (xs->xs_s0)
free(xs->xs_s0);
if (xs->xs_s1)
free(xs->xs_s1);
if (xs->xs_c0)
xpath_tree_free(xs->xs_c0);
if (xs->xs_c1)
xpath_tree_free(xs->xs_c1);
free(xs);
return 0;
}
/*! Given XML tree and xpath, parse xpath, eval it and return xpath context,
* This is a raw form of xpath where you can do type conversion, etc,
* not just a nodeset.
* @param[in] nsc External XML namespace context, or NULL
* @param[in] xpath String with XPATH 1.0 syntax
* @param[out] xptree Xpath-tree, parsed, structured XPATH, free:xpath_tree_free
* @retval 0 OK
* @retval -1 Error
* @code
* xpath_tree *xpt = NULL;
* if (xpath_parse(NULL, xpath, &xpt) < 0)
* err;
* if (xpt)
* xptree_free(xpt);
* @endcode
* @see xpath_tree_free
*/
int
xpath_parse(cvec *nsc,
char *xpath,
xpath_tree **xptree)
{
int retval = -1;
struct clicon_xpath_yacc_arg xy = {0,};
xy.xy_parse_string = xpath;
xy.xy_name = "xpath parser";
xy.xy_linenum = 1;
if (xpath_scan_init(&xy) < 0)
goto done;
if (xpath_parse_init(&xy) < 0)
goto done;
clicon_debug(2,"%s",__FUNCTION__);
if (clixon_xpath_parseparse(&xy) != 0) { /* yacc returns 1 on error */
clicon_log(LOG_NOTICE, "XPATH error: on line %d", xy.xy_linenum);
if (clicon_errno == 0)
clicon_err(OE_XML, 0, "XPATH parser error with no error code (should not happen)");
goto done;
}
if (debug > 1){
cbuf *cb = cbuf_new();
xpath_tree_print(cb, xy.xy_top);
clicon_debug(2, "xpath parse tree:\n%s", cbuf_get(cb));
cbuf_free(cb);
}
/* done: */
xpath_parse_exit(&xy);
xpath_scan_exit(&xy);
*xptree = xy.xy_top;
retval = 0;
done:
return retval;
}
/*! Given XML tree and xpath, parse xpath, eval it and return xpath context,
* This is a raw form of xpath where you can do type conversion of the return
* value, etc, not just a nodeset.
* @param[in] xcur XML-tree where to search
* @param[in] nsc External XML namespace context, or NULL
* @param[in] xpath String with XPATH 1.0 syntax
* @param[out] xrp Return XPATH context
* @retval 0 OK
* @retval -1 Error
* @code
* xp_ctx *xc = NULL;
* if (xpath_vec_ctx(x, NULL, xpath, &xc) < 0)
* err;
* if (xc)
* ctx_free(xc);
* @endcode
*/
int
xpath_vec_ctx(cxobj *xcur,
cvec *nsc,
char *xpath,
xp_ctx **xrp)
{
int retval = -1;
xpath_tree *xptree = NULL;
xp_ctx xc = {0,};
if (xpath_parse(nsc, xpath, &xptree) < 0)
goto done;
xc.xc_type = XT_NODESET;
xc.xc_node = xcur;
xc.xc_initial = xcur;
if (cxvec_append(xcur, &xc.xc_nodeset, &xc.xc_size) < 0)
goto done;
if (xp_eval(&xc, xptree, nsc, xrp) < 0)
goto done;
if (xc.xc_nodeset){
free(xc.xc_nodeset);
xc.xc_nodeset = NULL;
}
retval = 0;
done:
if (xptree)
xpath_tree_free(xptree);
return retval;
}
/*! Xpath nodeset function where only the first matching entry is returned
*
* @param[in] xcur XML tree where to search
* @param[in] nsc External XML namespace context, or NULL
* @param[in] xpformat Format string for XPATH syntax
* @retval xml-tree XML tree of first match
* @retval NULL Error or not found
*
* @code
* cxobj *x;
* cvec *nsc; // namespace context
* if ((x = xpath_first_nsc(xtop, nsc, "//symbol/foo")) != NULL) {
* ...
* }
* @endcode
* @note the returned pointer points into the original tree so should not be freed after use.
* @note return value does not see difference between error and not found
* @see also xpath_vec.
*/
cxobj *
xpath_first_nsc(cxobj *xcur,
cvec *nsc,
char *xpformat,
...)
{
cxobj *cx = NULL;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
va_start(ap, xpformat);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, xpformat);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
if (xpath_vec_ctx(xcur, nsc, xpath, &xr) < 0)
goto done;
if (xr && xr->xc_type == XT_NODESET && xr->xc_size)
cx = xr->xc_nodeset[0];
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return cx;
}
/*! Xpath nodeset function where only the first matching entry is returned
*
* @param[in] xcur XML tree where to search
* @param[in] xpformat Format string for XPATH syntax
* @retval xml-tree XML tree of first match
* @retval NULL Error or not found
*
* @code
* cxobj *x;
* if ((x = xpath_first(xtop, "//symbol/foo")) != NULL) {
* ...
* }
* @endcode
* @note the returned pointer points into the original tree so should not be freed after use.
* @note return value does not see difference between error and not found
* @see also xpath_vec.
* @see xpath_first_nsc which is more generic with namespace context
*/
cxobj *
xpath_first(cxobj *xcur,
char *xpformat,
...)
{
cxobj *cx = NULL;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
va_start(ap, xpformat);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, xpformat);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
if (xpath_vec_ctx(xcur, NULL, xpath, &xr) < 0)
goto done;
if (xr && xr->xc_type == XT_NODESET && xr->xc_size)
cx = xr->xc_nodeset[0];
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return cx;
}
/*! Given XML tree and xpath, returns nodeset as xml node vector
* If result is not nodeset, return empty nodeset
* @param[in] xcur xml-tree where to search
* @param[in] nsc External XML namespace context, or NULL
* @param[in] xpformat Format string for XPATH syntax
* @param[out] vec vector of xml-trees. Vector must be free():d after use
* @param[out] veclen returns length of vector in return value
* @retval 0 OK
* @retval -1 Error
* @code
* cvec *nsc; // namespace context
* cxobj **vec;
* size_t veclen;
* if (xpath_vec_nsc(xcur, nsc, "//symbol/foo", &vec, &veclen) < 0)
* goto err;
* for (i=0; i<veclen; i++){
* xn = vec[i];
* ...
* }
* free(vec);
* @endcode
*/
int
xpath_vec_nsc(cxobj *xcur,
cvec *nsc,
char *xpformat,
cxobj ***vec,
size_t *veclen,
...)
{
int retval = -1;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
va_start(ap, veclen);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, veclen);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
*vec=NULL;
*veclen = 0;
if (xpath_vec_ctx(xcur, nsc, xpath, &xr) < 0)
goto done;
if (xr && xr->xc_type == XT_NODESET){
*vec = xr->xc_nodeset;
xr->xc_nodeset = NULL;
*veclen = xr->xc_size;
}
retval = 0;
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return retval;
}
/*! Given XML tree and xpath, returns nodeset as xml node vector
* If result is not nodeset, return empty nodeset
* @param[in] xcur xml-tree where to search
* @param[in] xpformat Format string for XPATH syntax
* @param[out] vec vector of xml-trees. Vector must be free():d after use
* @param[out] veclen returns length of vector in return value
* @retval 0 OK
* @retval -1 Error
* @code
* cxobj **vec;
* size_t veclen;
* if (xpath_vec(xcur, "//symbol/foo", &vec, &veclen) < 0)
* goto err;
* for (i=0; i<veclen; i++){
* xn = vec[i];
* ...
* }
* free(vec);
* @endcode
* @see xpath_vec_nsc which is more generic with namespace context
*/
int
xpath_vec(cxobj *xcur,
char *xpformat,
cxobj ***vec,
size_t *veclen,
...)
{
int retval = -1;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
va_start(ap, veclen);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, veclen);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
*vec=NULL;
*veclen = 0;
if (xpath_vec_ctx(xcur, NULL, xpath, &xr) < 0)
goto done;
if (xr && xr->xc_type == XT_NODESET){
*vec = xr->xc_nodeset;
xr->xc_nodeset = NULL;
*veclen = xr->xc_size;
}
retval = 0;
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return retval;
}
/* Xpath that returns a vector of matches (only nodes marked with flags)
* @param[in] xcur xml-tree where to search
* @param[in] xpformat Format string for XPATH syntax
* @param[in] nsc External XML namespace context, or NULL
* @param[in] flags Set of flags that return nodes must match (0 if all)
* @param[out] vec vector of xml-trees. Vector must be free():d after use
* @param[out] veclen returns length of vector in return value
* @retval 0 OK
* @retval -1 error.
* @code
* cxobj **vec;
* size_t veclen;
* cvec *nsc; // namespace context (not NULL)
* if (xpath_vec_flag(xcur, nsc, "//symbol/foo", XML_FLAG_ADD, &vec, &veclen) < 0)
* goto err;
* for (i=0; i<veclen; i++){
* xn = vec[i];
* ...
* }
* free(vec);
* @endcode
* @Note that although the returned vector must be freed after use, the returned xml trees need not be.
* @see also xpath_vec This is a specialized version.
*/
int
xpath_vec_flag(cxobj *xcur,
cvec *nsc,
char *xpformat,
uint16_t flags,
cxobj ***vec,
size_t *veclen,
...)
{
int retval = -1;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
int i;
cxobj *x;
va_start(ap, veclen);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, veclen);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
*vec=NULL;
*veclen = 0;
if (xpath_vec_ctx(xcur, nsc, xpath, &xr) < 0)
goto done;
if (xr && xr->xc_type == XT_NODESET){
for (i=0; i<xr->xc_size; i++){
x = xr->xc_nodeset[i];
if (flags==0x0 || xml_flag(x, flags))
if (cxvec_append(x, vec, veclen) < 0)
goto done;
}
}
retval = 0;
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return retval;
}
/*! Given XML tree and xpath, returns boolean
* Returns true if the nodeset is non-empty
* @param[in] xcur xml-tree where to search
* @param[in] nsc External XML namespace context, or NULL
* @param[in] xpformat Format string for XPATH syntax
* @retval 1 True
* @retval 0 False
* @retval -1 Error
*/
int
xpath_vec_bool(cxobj *xcur,
cvec *nsc,
char *xpformat,
...)
{
int retval = -1;
va_list ap;
size_t len;
char *xpath = NULL;
xp_ctx *xr = NULL;
va_start(ap, xpformat);
len = vsnprintf(NULL, 0, xpformat, ap);
va_end(ap);
/* allocate a message string exactly fitting the message length */
if ((xpath = malloc(len+1)) == NULL){
clicon_err(OE_UNIX, errno, "malloc");
goto done;
}
/* second round: compute write message from reason and args */
va_start(ap, xpformat);
if (vsnprintf(xpath, len+1, xpformat, ap) < 0){
clicon_err(OE_UNIX, errno, "vsnprintf");
va_end(ap);
goto done;
}
va_end(ap);
if (xpath_vec_ctx(xcur, nsc, xpath, &xr) < 0)
goto done;
if (xr)
retval = ctx2boolean(xr);
done:
if (xr)
ctx_free(xr);
if (xpath)
free(xpath);
return retval;
}
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