1PMDAATTRIBUTE(3) Library Functions Manual PMDAATTRIBUTE(3)
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6 pmdaAttribute - informs a PMDA about client connection attributes
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9 #include <pcp/pmapi.h>
10 #include <pcp/pmda.h>
11 int pmdaAttribute(int context, int key, char *value, int length, pm‐
13 daExt *pmda);
14 cc ... -lpcp_pmda -lpcp
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18 As part of the Performance Metrics Domain Agent (PMDA) API (see
19 PMDA(3)), pmdaAttribute is the generic callback for responding to
20 client connection attributes. These attributes include client creden‐
21 tial information, such as user ID and group ID.
22 A PMDA that supports connection attributes will provide a private pm‐
24 daAttribute callback by assignment to version.six.attribute of the pm‐
25 daInterface structure, and implement custom logic for any of the attri‐
26 bute key-value pairs of interest to it.
27 All attributes are associated with a specific client context, and these
29 can be uniquely identified using the ctx first argument. The PMDA
30 should track client connections, and disconnections using the pmdaSe‐
31 tEndContextCallBack(3) interface, as a result. The pmdaGetContext(3)
32 interface may be particularly helpful also.
33 All attributes are passed as key-value pairs and the value is always
35 passed as a null-terminated string of given length. This includes nu‐
36 meric attributes like the user ID.
37 The most commonly used attributes would be PCP_ATTR_USERID and
39 PCP_ATTR_GROUPID but others may also be optionally passed (such as
40 PCP_ATTR_USERNAME) if they are available. Some attributes will be con‐
41 sumed by pmcd and never through passed to PMDAs, such as PCP_ATTR_PASS‐
42 WORD. A complete list of all possible attributes can be found in the
43 headers listed above, all are prefixed by PCP_ATTR.
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46 The PMDA must be using PMDA_PROTOCOL_6 or later, as specified in the
47 call to pmdaDSO(3) or pmdaDaemon(3).
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50 pmdaAttribute should return either zero on success, or a negative re‐
51 turn code to indicate an error in handling the attribute. This return
52 code cannot be used to indicate a client should be disallowed access -
53 such functionality must be performed by the agent in response to call‐
54 backs for the client in question (using PM_ERR_PERMISSION for those
55 specific callbacks, for that specific client. In other words, errors
56 will be be passed to PMCD but there is no guarantee made that the error
57 will be return to the client and result in termination of the client,
58 for example.
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61 PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3) and pmdaGet‐
62 Context(3).
63Performance Co-Pilot PCP PMDAATTRIBUTE(3)