NAME

       __pmParseHostAttrsSpec,  __pmUnparseHostAttrsSpec,  __pmFreeHostAttrsSpec,  __pmFreeAttrsSpec  - host and
       attributes specification parser

C SYNOPSIS

       #include "pmapi.h"
       #include "libpcp.h"

       int __pmParseHostAttrsSpec(const char *string, pmHostSpec **hostsp, int *count, __pmHashCtl *attrs,
               char **errmsg);
       int __pmUnparseHostAttrsSpec(pmHostSpec *hostsp, int *count, __pmHashCtl *attrs, char *string, size_t
               size);
       void __pmFreeHostAttrsSpec(pmHostSpec *hosts, int count, __pmHashCtl *attrs);
       void __pmFreeAttrsSpec(__pmHashCtl *attrs);

       cc ... -lpcp

CAVEAT

       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.

DESCRIPTION

       __pmParseHostAttrsSpec  accepts  a  string  specifying the location of a PCP performance metric collector
       daemon, and any attributes that should be associated with the connection to that daemon.

       The syntax allows the optional specification of a protocol (native PCP protocol, encrypted  PCP  protocol
       or unix domain socket protocol).

       If  the specified protocol is native PCP protocol, or encrypted PCP protocol, an initial pmcd(1) hostname
       with optional port numbers and optional proxy host, and optional attributes which are  to  be  associated
       with the connection may be specified.  Some examples follow:

            pcp://nas1.servers.com:44321@firewalls.r.us?compress
            pcps://nas1.servers.com?user=otto&pass=blotto&compress

       If  the  specified  protocol  is  a unix domain socket protocol, the path to the socket in the local file
       system may be specified along with optional attributes which are to be associated  with  the  connection.
       For example:

            unix://$PCP_RUN_DIR/pmcd.socket:?compress
            local://my/local/pmcd.socket:?user=otto&pass=blotto&compress

       If the optional protocol component is not specified, then the default setting will be used - which is the
       native PCP binary protocol.  However, this can still be overwritten via the environment as  described  in
       PCPIntro(1).   If  the protocol prefix is specified, it must be one of either "pcp://" (clear), "pcps://"
       (secure, encrypted), "unix://" (authenticated local) or "local://" ("unix://" then "pcp://").

       The path specified for the "unix://" and "local://" protocols will always be interpreted as  an  absolute
       path name. For example, the following are all interpreted identically as $PCP_RUN_DIR/pmcd.socket.

            unix://$PCP_RUN_DIR/pmcd.socket
            unix:/$PCP_RUN_DIR/pmcd.socket
            unix:$PCP_RUN_DIR/pmcd.socket

       Refer to __pmParseHostSpec(3) for further details of the host and proxy host components.

       If  any  optional  connection  attributes  are  to  be  specified,  these are separated from the hostname
       component via the '?' character.  Each attribute is separated by the  '&'  character,  and  each  can  be
       either a simple attribute flag (such as "compress") or a name=value pair (such as "username=fred").

       __pmParseHostAttrsSpec  takes  a  null-terminated host-and-attributes specification string and returns an
       array of pmHostSpec structures, where the array has count entries, and an attrs hash table containing any
       attributes (including the optional protocol, if it was specified).

       Full details of the pmHostSpec structures are provided in __pmParseHostSpec(3).

       The  __pmHashCtl  structure  that  is  filled  out  on  return via attributes, represents each individual
       attribute in the specification string with any associated value.   It  should  be  considered  an  opaque
       structure and should be zeroed beforehand.

       The  returned hash table control structure can be iterated using one of the supplied iteration mechanisms
       - __pmHashWalkCB (a callback-based mechanism) or __pmHashWalk (a  simple  procedural  mechanism).   These
       provide  access  to  the  individual hash nodes, as __pmHashNode entries, which provide access to decoded
       attributes and their (optional) values.

           typedef struct __pmHashNode {
               __pmHashNode    *next;    /* next node in hash bucket (internal) */
               unsigned int    key;      /* key identifying particular attribute */
               void            *data;    /* attributes value (optional, string) */
           } __pmHashNode;

       There are a set number of valid attributes, however these may be  extended  in  future  releases  as  new
       connection parameters become needed.  These can be identified via the PCP_ATTR_* macros in the PCP header
       files.

       __pmUnparseHostSpec performs the inverse operation, creating  a  string  representation  from  hosts  and
       attributes  structures.   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 __pmParseHostAttrsSpec returns zero.  In this case the dynamic
       storage  allocated  by  __pmParseHostAttrsSpec can be released by calling __pmFreeHostAttrsSpec using the
       addresses returned from __pmParseHostAttrsSpec

       Alternatively, the hosts and attributes memory can be freed  separately,  using  __pmFreeHostSpec(3)  and
       __pmFreeAttrsSpec.

       __pmParseHostAttrsSpec 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(3)
       the error message string in this situation.

       In  the  case  of  an  error, both hosts and attributes are undefined.  In the case of success, errmsg is
       undefined.

       On success __pmUnparseHostAttrsSpec 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 will be returned.

SEE ALSO

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