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pcmk_rule.c
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/*
* Copyright 2022-2024 the Pacemaker project contributors
*
* The version control history for this file may have further details.
*
* This source code is licensed under the GNU Lesser General Public License
* version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY.
*/
#include <crm_internal.h>
#include <crm/cib/internal.h>
#include <crm/common/cib.h>
#include <crm/common/iso8601.h>
#include <crm/common/xml.h>
#include <crm/pengine/internal.h>
#include <crm/pengine/rules_internal.h>
#include <pacemaker-internal.h>
#include "libpacemaker_private.h"
#define XPATH_NODE_RULE "//" PCMK_XE_RULE "[@" PCMK_XA_ID "='%s']"
/*!
* \internal
* \brief Check whether a given rule is in effect
*
* \param[in] scheduler Scheduler data
* \param[in] rule_id The ID of the rule to check
* \param[out] error Where to store a rule evaluation error message
*
* \return Standard Pacemaker return code
*/
static int
eval_rule(pcmk_scheduler_t *scheduler, const char *rule_id, const char **error)
{
xmlNodePtr cib_constraints = NULL;
xmlNodePtr match = NULL;
xmlXPathObjectPtr xpath_obj = NULL;
char *xpath = NULL;
int rc = pcmk_rc_ok;
int num_results = 0;
*error = NULL;
/* Rules are under the constraints node in the XML, so first find that. */
cib_constraints = pcmk_find_cib_element(scheduler->input,
PCMK_XE_CONSTRAINTS);
/* Get all rules matching the given ID that are also simple enough for us
* to check. For the moment, these rules must only have a single
* date_expression child and:
* - Do not have a date_spec operation, or
* - Have a date_spec operation that contains years=
*
* We do this in steps to provide better error messages. First, check that
* there's any rule with the given ID.
*/
xpath = crm_strdup_printf(XPATH_NODE_RULE, rule_id);
xpath_obj = xpath_search(cib_constraints, xpath);
num_results = numXpathResults(xpath_obj);
free(xpath);
freeXpathObject(xpath_obj);
if (num_results == 0) {
*error = "Rule not found";
return ENXIO;
}
if (num_results > 1) {
// Should not be possible; schema prevents this
*error = "Found more than one rule with matching ID";
return pcmk_rc_duplicate_id;
}
/* Next, make sure it has exactly one date_expression. */
xpath = crm_strdup_printf(XPATH_NODE_RULE "//date_expression", rule_id);
xpath_obj = xpath_search(cib_constraints, xpath);
num_results = numXpathResults(xpath_obj);
free(xpath);
freeXpathObject(xpath_obj);
if (num_results != 1) {
if (num_results == 0) {
*error = "Rule does not have a date expression";
} else {
*error = "Rule has more than one date expression";
}
return EOPNOTSUPP;
}
/* Then, check that it's something we actually support. */
xpath = crm_strdup_printf(XPATH_NODE_RULE
"//" PCMK_XE_DATE_EXPRESSION
"[@" PCMK_XA_OPERATION
"!='" PCMK_VALUE_DATE_SPEC "']",
rule_id);
xpath_obj = xpath_search(cib_constraints, xpath);
num_results = numXpathResults(xpath_obj);
free(xpath);
if (num_results == 0) {
freeXpathObject(xpath_obj);
xpath = crm_strdup_printf(XPATH_NODE_RULE
"//" PCMK_XE_DATE_EXPRESSION
"[@" PCMK_XA_OPERATION
"='" PCMK_VALUE_DATE_SPEC "' "
"and " PCMK_XE_DATE_SPEC
"/@" PCMK_XA_YEARS "]",
rule_id);
xpath_obj = xpath_search(cib_constraints, xpath);
num_results = numXpathResults(xpath_obj);
free(xpath);
if (num_results == 0) {
freeXpathObject(xpath_obj);
*error = "Rule must either not use " PCMK_XE_DATE_SPEC ", or use "
PCMK_XE_DATE_SPEC " with " PCMK_XA_YEARS "=";
return EOPNOTSUPP;
}
}
match = getXpathResult(xpath_obj, 0);
/* We should have ensured this with the xpath query above, but double-
* checking can't hurt.
*/
pcmk__assert((match != NULL)
&& (pcmk__condition_type(match) == pcmk__condition_datetime));
rc = pcmk__evaluate_date_expression(match, scheduler->priv->now, NULL);
if ((rc != pcmk_rc_ok) && (rc != pcmk_rc_within_range)) {
// Malformed or missing
*error = "Error parsing rule";
}
freeXpathObject(xpath_obj);
return rc;
}
/*!
* \internal
* \brief Check whether each rule in a list is in effect
*
* \param[in,out] out Output object
* \param[in] input The CIB XML to check (if \c NULL, use current CIB)
* \param[in] date Check whether the rule is in effect at this date and
* time (if \c NULL, use current date and time)
* \param[in] rule_ids The IDs of the rules to check, as a <tt>NULL</tt>-
* terminated list.
*
* \return Standard Pacemaker return code
*/
int
pcmk__check_rules(pcmk__output_t *out, xmlNodePtr input, const crm_time_t *date,
const char **rule_ids)
{
pcmk_scheduler_t *scheduler = NULL;
int rc = pcmk_rc_ok;
pcmk__assert(out != NULL);
if (rule_ids == NULL) {
// Trivial case; every rule specified is in effect
return pcmk_rc_ok;
}
rc = pcmk__init_scheduler(out, input, date, &scheduler);
if (rc != pcmk_rc_ok) {
return rc;
}
for (const char **rule_id = rule_ids; *rule_id != NULL; rule_id++) {
const char *error = NULL;
int last_rc = eval_rule(scheduler, *rule_id, &error);
out->message(out, "rule-check", *rule_id, last_rc, error);
if (last_rc != pcmk_rc_ok) {
rc = last_rc;
}
}
pe_free_working_set(scheduler);
return rc;
}
// Documented in pacemaker.h
int
pcmk_check_rules(xmlNodePtr *xml, xmlNodePtr input, const crm_time_t *date,
const char **rule_ids)
{
pcmk__output_t *out = NULL;
int rc = pcmk_rc_ok;
rc = pcmk__xml_output_new(&out, xml);
if (rc != pcmk_rc_ok) {
return rc;
}
pcmk__register_lib_messages(out);
rc = pcmk__check_rules(out, input, date, rule_ids);
pcmk__xml_output_finish(out, pcmk_rc2exitc(rc), xml);
return rc;
}

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