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conf: improve matching rules a bit more
Handle "null", null, !null, "!null", !"null" and "!\"null\"" matches, copy some docs from wireplumber about the rules and add some more cases.
This commit is contained in:
Wim Taymans
parent
c52c56621d
commit
0e380de809
2 changed files with 140 additions and 21 deletions
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@ -434,13 +434,105 @@ The general rules object follows the following pattern:
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}
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]
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```
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Match rules are an array of rules.
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The rules is an array of things to match and what actions to perform
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when a match is found.
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A rule is always a JSON object with two keys: matches and actions. The matches key is used to
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define the conditions that need to be met for the rule to be evaluated as true, and the actions
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key is used to define the actions that are performed when the rule is evaluated as true.
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The matches key is always a JSON array of objects, where each object defines a condition that needs
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to be met. Each condition is a list of key-value pairs, where the key is the name of the property
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that is being matched, and the value is the value that the property needs to have. Within a condition,
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all the key-value pairs are combined with a logical AND, and all the conditions in the matches
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array are combined with a logical OR.
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The actions key is always a JSON object, where each key-value pair defines an action that is
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performed when the rule is evaluated as true. The action name is specific to the rule and is
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defined by the rule’s documentation, but most frequently you will see the update-props action,
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which is used to update the properties of the matched object.
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In the matches array, it is also possible to use regular expressions to match property values.
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For example, to match all nodes with a name that starts with my_, you can use the following condition:
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```
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matches = [
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{
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node.name = "~my_.*"
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}
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]
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```
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The ~ character signifies that the value is a regular expression. The exact syntax of the regular
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expressions is the POSIX extended regex syntax, as described in the regex (7) man page.
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In addition to regular expressions, you may also use the ! character to negate a condition. For
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example, to match all nodes with a name that does not start with my_, you can use the following condition:
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```
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matches = [
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{
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node.name = "!~my_.*"
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}
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]
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```
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The ! character can be used with or without a regular expression. For example, to match all
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nodes with a name that is not equal to my_node, you can use the following condition:
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```
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matches = [
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{
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node.name = "!my_node"
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}
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]
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```
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The null value has a special meaning; it checks if the property is not available
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(or unset). To check if a property is not set:
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```
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matches = [
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{
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node.name = null
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}
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]
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```
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To check the existence of a property, one can use the !null condition, for example:
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```
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matches = [
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{
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node.name = "!null"
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}
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{
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node.name = !null # simplified syntax
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}
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]
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```
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To handle the "null" string, one needs to escape the string. For example, to check
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if a property has the string value "null", use:
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```
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matches = [
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{
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node.name = "null"
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}
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]
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```
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To handle anything but the "null" string, use:
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```
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matches = [
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{
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node.name = "!\"null\""
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}
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{
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node.name = !"null" # simplified syntax
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}
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]
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```
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The available actions and their values depend on the specific rule
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that is used. Usually it is possible to update some properties or set
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some quirks on the object.
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# CONTEXT PROPERTIES RULES @IDX@ pipewire.conf
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@ -594,6 +594,14 @@ static int load_module(struct pw_context *context, const char *key, const char *
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* <key> = <value>
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* ...
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* }
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*
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* Some things that can match:
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*
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* null -> matches when the property is not found
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* "null" -> matches when the property is found and has the string "null"
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* !null -> matches when the property is found (any value)
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* "!null" -> same as !null
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* !"null" and "!\"null\"" matches anything that is not the string "null"
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*/
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static bool find_match(struct spa_json *arr, const struct spa_dict *props)
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{
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@ -606,47 +614,66 @@ static bool find_match(struct spa_json *arr, const struct spa_dict *props)
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int len;
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while (spa_json_get_string(&it[0], key, sizeof(key)) > 0) {
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bool success = false, is_null;
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bool success = false, is_null, reg = false, parse_string = true;
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int skip = 0;
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if ((len = spa_json_next(&it[0], &value)) <= 0)
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break;
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if (len > 0 && value[0] == '!') {
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/* first decode a string, when there was a string, we assume it
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* can not be null but the "null" string, unless there is a modifier,
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* see below. */
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if (spa_json_is_string(value, len)) {
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if (spa_json_parse_stringn(value, len, val, sizeof(val)) < 0)
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continue;
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value = val;
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len = strlen(val);
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parse_string = false;
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}
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/* parse the modifiers, after the modifier we unescape the string
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* again to be able to detect and handle null and "null" */
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if (len > skip && value[skip] == '!') {
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success = !success;
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skip++;
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parse_string = true;
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}
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if (len > skip && value[skip] == '~') {
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reg = true;
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skip++;
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parse_string = true;
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}
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str = spa_dict_lookup(props, key);
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is_null = spa_json_is_null(value+skip, len-skip);
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/* parse the remaining part of the string, if there was a modifier,
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* we need to check for null again. Otherwise null was in quotes without
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* a modifier. */
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is_null = parse_string && spa_json_is_null(value+skip, len-skip);
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if (is_null || str == NULL) {
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if (is_null && str == NULL)
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success = !success;
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} else {
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if (spa_json_parse_stringn(value+skip, len-skip, val, sizeof(val)) < 0)
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/* only unescape string once or again after modifier */
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if (!parse_string) {
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memmove(val, value+skip, len-skip);
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val[len-skip] = '\0';
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} else if (spa_json_parse_stringn(value+skip, len-skip, val, sizeof(val)) < 0)
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continue;
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value = val;
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len = strlen(val);
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if (len > 0 && value[0] == '!') {
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success = !success;
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skip++;
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}
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if (value[skip] == '~') {
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if (reg) {
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regex_t preg;
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int res;
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skip++;
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if ((res = regcomp(&preg, value+skip, REG_EXTENDED | REG_NOSUB)) != 0) {
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if ((res = regcomp(&preg, val, REG_EXTENDED | REG_NOSUB)) != 0) {
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char errbuf[1024];
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regerror(res, &preg, errbuf, sizeof(errbuf));
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pw_log_warn("invalid regex %s: %s", value+skip, errbuf);
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pw_log_warn("invalid regex %s: %s", val, errbuf);
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} else {
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if (regexec(&preg, str, 0, NULL, 0) == 0)
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success = !success;
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regfree(&preg);
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}
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} else if (strncmp(str, value+skip, len-skip) == 0 &&
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strlen(str) == (size_t)(len-skip)) {
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} else if (strcmp(str, val) == 0) {
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success = !success;
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}
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}
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