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   pmdaattribute    ( 3 )

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Имя (Name)

pmdaAttribute - informs a PMDA about client connection attributes

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Синопсис C (C Synopsis)

#include <pcp/pmapi.h>
       #include <pcp/pmda.h>

       int pmdaAttribute(int context, int key, char *value, int length,
       pmdaExt *pmda);

       cc ... -lpcp_pmda -lpcp

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Описание (Description)

As part of the Performance Metrics Domain Agent (PMDA) API (see
       PMDA(3)), pmdaAttribute is the generic callback for responding to
       client connection attributes.  These attributes include client
       credential information, such as user ID and group ID.

       A PMDA that supports connection attributes will provide a private
       pmdaAttribute callback by assignment to version.six.attribute of
       the pmdaInterface structure, and implement custom logic for any
       of the attribute key-value pairs of interest to it.

       All attributes are associated with a specific client context, and
       these can be uniquely identified using the ctx first argument.
       The PMDA should track client connections, and disconnections
       using the pmdaSetEndContextCallBack(3) interface, as a result.
       The pmdaGetContext(3) interface may be particularly helpful also.

       All attributes are passed as key-value pairs and the value is
       always passed as a null-terminated string of given length.  This
       includes numeric attributes like the user ID.

       The most commonly used attributes would be PCP_ATTR_USERID and
       PCP_ATTR_GROUPID but others may also be optionally passed (such
       as PCP_ATTR_USERNAME) if they are available.  Some attributes
       will be consumed by pmcd and never through passed to PMDAs, such
       as PCP_ATTR_PASSWORD.  A complete list of all possible attributes
       can be found in the headers listed above, all are prefixed by
       PCP_ATTR.

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Предостережение (Caveat)

The PMDA must be using PMDA_PROTOCOL_6 or later, as specified in
       the call to pmdaDSO(3) or pmdaDaemon(3).

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Диагностика (Diagnostic)

pmdaAttribute should return either zero on success, or a negative
       return code to indicate an error in handling the attribute.  This
       return code cannot be used to indicate a client should be
       disallowed access - such functionality must be performed by the
       agent in response to callbacks for the client in question (using
       PM_ERR_PERMISSION for those specific callbacks, for that specific
       client.  In other words, errors will be be passed to PMCD but
       there is no guarantee made that the error will be return to the
       client and result in termination of the client, for example.

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Смотри также (See also)

PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3) and
       pmdaGetContext(3).

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