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NAME | C SYNOPSIS | CAVEAT | DESCRIPTION | RETURN VALUE | SEE ALSO | COLOPHON |
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PMPARSEHOSTSPEC(3) Library Functions Manual PMPARSEHOSTSPEC(3)
__pmParseHostSpec, __pmUnparseHostSpec, __pmFreeHostSpec - uniform
host specification parser
#include "pmapi.h"
#include "libpcp.h"
int __pmParseHostSpec(const char *string, __pmHostSpec **hostsp,
int *count, char **errmsg);
int __pmUnparseHostSpec(__pmHostSpec *hosts, int count,
char *string, size_t size);
void __pmFreeHostSpec(__pmHostSpec *hosts, int count);
cc ... -lpcp
This documentation is intended for internal Performance Co-Pilot
(PCP) developer use.
These interfaces are not part of the PCP APIs that are guaranteed
to remain fixed across releases, and they may not work, or may
provide different semantics at some point in the future.
__pmParseHostSpec accepts a string specifying the location of a
PCP performance metric collector daemon. The syntax of the vari‐
ous formats of this string is described in PCPIntro(1) where sev‐
eral examples are also presented.
The syntax allows the initial pmcd(1) hostname to be optionally
followed by a list of port numbers, which will be tried in order
when connecting to pmcd on that host. The list of port numbers is
separated from the hostname using a colon, and each port in the
list is comma-separated.
In addition, one or more optional pmproxy(1) hosts can be speci‐
fied (currently, only one proxy host is supported by the PCP pro‐
tocols). These are separated from each other and from the pmcd
component using the @ character. These may also be followed by an
optional port list, using the same comma-separated syntax as be‐
fore.
__pmParseHostSpec takes a null-terminated host specification
string and returns an array of __pmHostSpec structures, where the
array has count entries.
These __pmHostSpec structures that are returned via hostsp repre‐
sent each individual host in the specification string and has the
following declaration:
typedef struct {
char *name; /* hostname (always valid) */
int *ports; /* array of host port numbers */
int nports; /* number of ports in host port array */
} __pmHostSpec;
__pmUnparseHostSpec performs the inverse operation, creating a
string representation from a number of hosts structures. Where
the count of structures indicated by hosts is greater than one,
the proxy syntax is used to indicate a chain of proxied hosts.
The size of the supplied string buffer must be provided by the
caller using the size parameter.
If the given string is successfully parsed __pmParseHostSpec re‐
turns zero. In this case the dynamic storage allocated by __pm‐
ParseHostSpec can be released by calling __pmFreeHostSpec using
the address returned from __pmParseHostSpec via hosts.
__pmParseHostSpec returns PM_ERR_GENERIC and a dynamically allo‐
cated error message string in errmsg, if the given string does not
parse, and the user-supplied errmsg pointer is non-null. Be sure
to free(3) the error message string in this situation.
In the case of an error, hosts is undefined. In the case of suc‐
cess, errmsg is undefined.
On success __pmUnparseHostSpec returns a positive value indicating
the number of characters written into the supplied buffer. Howev‐
er, if the supplied buffer was too small, a negative status code
of -E2BIG is returned.
pmcd(1), pmproxy(1), pmchart(1), __pmParseHostAttrsSpec(3),
PMAPI(3) and pmNewContext(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
pcp@groups.io. 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 man-pages@man7.org
Performance Co-Pilot PCP PMPARSEHOSTSPEC(3)
Pages that refer to this page: pmparsehostattrsspec(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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