Ubuntu Manpage: __pmParseHostAttrsSpec, __pmUnparseHostAttrsSpec, __pmFreeHostAttrsSpec, _

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.

NAME

C SYNOPSIS

CAVEAT

DESCRIPTION

RETURN VALUE

SEE ALSO