PMPARSEHOSTSPEC(3)					     Library Functions Manual						PMPARSEHOSTSPEC(3)

NAME

       __pmParseHostSpec, __pmUnparseHostSpec, __pmFreeHostSpec - uniform host specification parser

C SYNOPSIS

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

DESCRIPTION

       __pmParseHostSpec accepts a string specifying the location of a PCP performance metric collector daemon.  The syntax of the various formats
       of this string is described in PCPIntro(1) where several 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  con-
       necting to pmcd on that host.  The portlist 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 specified (currently, only one proxy host is supported by the PCP protocols).
       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 before.

       __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 represent 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.

RETURN VALUE

       If the given string is successfully parsed __pmParseHostSpec returns zero.  In this case the dynamic storage allocated by __pmParseHostSpec
       can be released by calling __pmFreeHostSpec using the address returned from __pmParseHostSpec via hosts.

       __pmParseHostSpec returns PM_ERR_GENERIC and a dynamically allocated 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(3C) the error message string in this situation.

       In the case of an error, hosts is undefined.  In the case of success, errmsg is undefined.

       On  success __pmUnparseHostSpec returns a positive value indicating the number of characters written into the supplied buffer.  However, if
       the supplied buffer was too small, a negative status code of -E2BIG is returned.

SEE ALSO

       pmcd(1), pmproxy(1), pmchart(1), __pmParseHostAttrsSpec(3), PMAPI(3) and pmNewContext(3).

Performance Co-Pilot							PCP							PMPARSEHOSTSPEC(3)