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NAME | C SYNOPSIS | DESCRIPTION | CAVEAT | DIAGNOSTICS | SEE ALSO | COLOPHON |
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PMDAATTRIBUTE(3) Library Functions Manual PMDAATTRIBUTE(3)
pmdaAttribute - informs a PMDA about client connection attributes
#include <pcp/pmapi.h>
#include <pcp/pmda.h>
int pmdaAttribute(int context, int key, char *value, int length,
pmdaExt *pmda);
cc ... -lpcp_pmda -lpcp
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 al‐
ways passed as a null-terminated string of given length. This in‐
cludes 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_AT‐
TR.
The PMDA must be using PMDA_INTERFACE_6 or later, as specified in
the call to pmdaDSO(3) or pmdaDaemon(3).
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 disal‐
lowed 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.
PMAPI(3), PMDA(3), pmdaDaemon(3), pmdaDSO(3), pmdaMain(3) and
pmdaGetContext(3).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation about the project can be found at ⟨http://www.pcp.io/⟩.
If you have a bug report for this manual page, send it to
[email protected]. This page was obtained from the project's upstream
Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page,
or you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a
mail to [email protected]
Performance Co-Pilot PCP PMDAATTRIBUTE(3)
Pages that refer to this page: pmdamain(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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