Functions¶

int keyCmp (const Key *k1, const Key *k2)
Compare the name of two keys. int keyNeedSync (const Key *key)
Test if a key needs to be synced to backend storage. int keyIsSystem (const Key *key)
Check whether a key is under the system namespace or not. int keyIsUser (const Key *key)
Check whether a key is under the user namespace or not. int keyIsBelow (const Key *key, const Key *check)
Check if the key check is below the key key or not. int keyIsDirectBelow (const Key *key, const Key *check)
Check if the key check is direct below the key key or not. int keyRel (const Key *key, const Key *check)
Information about the relation in the hierarchy between two keys. int keyIsInactive (const Key *key)
Check whether a key is inactive. int keyIsBinary (const Key *key)
Check if a key is binary type. int keyIsString (const Key *key)
Check if a key is string type.

int keyCmp (const Key * k1, const Key * k2)¶

Compare the name of two keys.

Returns:

The comparison is based on a strcmp of the keynames, and iff they match a strcmp of the owner will be used to distuingish. If even this matches the keys are found to be exactly the same and 0 is returned. These two keys can't be used in the same KeySet.

keyCmp() defines the sorting order for a KeySet.

The following 3 points are the rules for null values:

• A null pointer will be found to be smaller than every other key. If both are null pointers, 0 is returned.
• A null name will be found to be smaller than every other name. If both are null names, 0 is returned.

If the name is equal then:

•

No owner will be found to be smaller then every other owner. If both don't have a owner, 0 is returned.

Note:

Often is enough to know if the other key is less then or greater then the other one. But Sometimes you need more precise information, see keyRel().

Given any Keys k1 and k2 constructed with keyNew(), following equation hold true:

Here are some more examples:

1 Key *k1 = keyNew("user/a", KEY_END);
2 Key *k2 = keyNew("user/b", KEY_END);
3 
4 // keyCmp(k1,k2) < 0
5 // keyCmp(k2,k1) > 0

And even more:

1 Key *k1 = keyNew("user/a", KEY_OWNER, "markus", KEY_END);
2 Key *k2 = keyNew("user/a", KEY_OWNER, "max", KEY_END);
3 
4 // keyCmp(k1,k2) < 0
5 // keyCmp(k2,k1) > 0

Do not strcmp the keyName() yourself because the result differs from simple ascii comparison.

Parameters:

See also:

int keyIsBelow (const Key * key, const Key * check)¶

Check if the key check is below the key key or not. Example:

key user/sw/app
check user/sw/app/key

returns true because check is below key

Example:

key user/sw/app
check user/sw/app/folder/key

returns also true because check is indirect below key

Obviously, there is no key above a namespace (e.g. user, system, /):

key *
check user

Parameters:

Return values:

See also:

int keyIsBinary (const Key * key)¶

Check if a key is binary type. The function checks if the key is a binary. Opposed to string values binary values can have '\0' inside the value and may not be terminated by a null character. Their disadvantage is that you need to pass their size.

Make sure to use this function and don't test the binary type another way to ensure compatibility and to write less error prone programs.

Return values:

See also:

Parameters:

int keyIsDirectBelow (const Key * key, const Key * check)¶

Check if the key check is direct below the key key or not.

Example:
key user/sw/app
check user/sw/app/key
returns true because check is below key
Example:
key user/sw/app
check user/sw/app/folder/key
does not return true, because there is only a indirect relation

Parameters:

Return values:

See also:

int keyIsInactive (const Key * key)¶

Check whether a key is inactive. In Elektra terminology a hierarchy of keys is inactive if the rootkey's basename starts with '.'. So a key is also inactive if it is below an inactive key. For example, user/key/.hidden is inactive and so is user/.hidden/below.

Inactive keys should not have any meaning to applications, they are only a convention reserved for users and administrators. To automatically remove all inactive keys for an application, consider to use the hidden plugin.

Parameters:

Return values:

int keyIsString (const Key * key)¶

Check if a key is string type. String values are null terminated and are not allowed to have any '\0' characters inside the string.

Make sure to use this function and don't test the string type another way to ensure compatibility and to write less error prone programs.

Return values:

See also:

Parameters:

int keyIsSystem (const Key * key)¶

Check whether a key is under the system namespace or not.

Parameters:

Return values:

See also:

int keyIsUser (const Key * key)¶

Check whether a key is under the user namespace or not.

Parameters:

Return values:

See also:

int keyNeedSync (const Key * key)¶

Test if a key needs to be synced to backend storage. If any key modification took place the key will be flagged so that kdbSet() knows which keys were modified and which not.

After keyNew() the flag will normally be set, but after kdbGet() and kdbSet() the flag will be removed. When you modify the key the flag will be set again.

In your application you can make use of that flag to know if you changed something in a key after a kdbGet() or kdbSet().

Note:

Deprecated

See also:

Parameters:

Return values:

int keyRel (const Key * key, const Key * check)¶

Information about the relation in the hierarchy between two keys. Unlike keyCmp() the number gives information about hierarchical information.

•

If the keys are the same 0 is returned. So it is the key itself.

user/key
user/key

1 keySetName (key, "user/key/folder");
2 keySetName (check, "user/key/folder");
3 succeed_if (keyRel (key, check) == 0, "should be same");

Note:

•

If the key is direct below the other one 1 is returned. That means that, in terms of hierarchy, no other key is between them - it is a direct child.

user/key/folder
user/key/folder/child

1 keySetName (key, "user/key/folder");
2 keySetName (check, "user/key/folder/child");
3 succeed_if (keyRel (key, check) == 1, "should be direct below");

•

If the key is below the other one, but not directly 2 is returned. This is also called grand-child.

user/key/folder
user/key/folder/any/depth/deeper/grand-child

1 keySetName (key, "user/key/folder");
2 keySetName (check, "user/key/folder/any/depth/deeper/grand-child");
3 succeed_if (keyRel (key, check) >= 2, "should be below (but not direct)");
4 succeed_if (keyRel (key, check) > 0, "should be below");
5 succeed_if (keyRel (key, check) >= 0, "should be the same or below");

• If a invalid or null ptr key is passed, -1 is returned
• If the keys have no relations, but are not invalid, -2 is returned.
• If the keys are in the same hierarchy, a value smaller then -2 is returned. It means that the key is not below.

user/key/myself
user/key/sibling

1 keySetName (key, "user/key/folder");
2 keySetName (check, "user/notsame/folder");
3 succeed_if (keyRel (key, check) < -2, "key is not below, but same namespace");

TODO Below is an idea how it could be extended: It could continue the search into the other direction if any (grand-)parents are equal.

•

If the keys are direct below a key which is next to the key, -2 is returned. This is also called nephew. (TODO not implemented)

user/key/myself
user/key/sibling

•

If the keys are direct below a key which is next to the key, -2 is returned. This is also called nephew. (TODO not implemented)

user/key/myself
user/key/sibling/nephew

•

If the keys are below a key which is next to the key, -3 is returned. This is also called grand-nephew. (TODO not implemented)

user/key/myself
user/key/sibling/any/depth/deeper/grand-nephew

The same holds true for the other direction, but with negative values. For no relation INT_MIN is returned.

Note:

Returns:

Return values:

Parameters: