path: root/man/man3/pmparsehostattrsspec.3

'\"macro stdmacro
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.TH PMPARSEHOSTATTRSSPEC 3 "PCP" "Performance Co-Pilot"
.SH NAME
\f3__pmParseHostAttrsSpec\f1,
\f3__pmUnparseHostAttrsSpec\f1,
\f3__pmFreeHostAttrsSpec\f1,
\f3__pmFreeAttrsSpec\f1 \- host and attributes specification parser
.SH "C SYNOPSIS"
.ft 3
#include <pcp/pmapi.h>
.br
#include <pcp/impl.h>
.sp
.ad l
.hy 0
.in +8n
.ti -8n
int __pmParseHostAttrsSpec(const char *\fIstring\fP, pmHostSpec **\fIhostsp\fP, int\ *\fIcount\fP, __pmHashCtl\ *\fIattrs\fP, char\ **\fIerrmsg\fP);
.br
.ti -8n
int __pmUnparseHostAttrsSpec(pmHostSpec *\fIhostsp\fP, int\ *\fIcount\fP, __pmHashCtl\ *\fIattrs\fP, char\ *\fIstring\fP, size_t \fIsize\fP);
.br
.ti -8n
void __pmFreeHostAttrsSpec(pmHostSpec *\fIhosts\fP, int \fIcount\fP, __pmHashCtl\ *\fIattrs\fP);
.br
.ti -8n
void __pmFreeAttrsSpec(__pmHashCtl\ *\fIattrs\fP);
.sp
.in
.hy
.ad
cc ... \-lpcp
.ft 1
.SH DESCRIPTION
.B __pmParseHostAttrsSpec
accepts a
.B string
specifying the location of a PCP performance metric collector daemon,
and any attributes that should be associated with the connection to that
daemon.
.PP
The syntax allows the optional specification of a protocol (native PCP
protocol, encrypted PCP protocol or unix domain socket protocol).
.PP
If the specified protocol is native PCP protocol, or encrypted PCP protocol,
an initial
.BR 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:
.PP
.in +0.5i
.nf
.ft CW
pcp://nas1.servers.com:44321@firewalls.r.us?compress
pcps://nas1.servers.com?user=otto&pass=blotto&compress
.ft R
.fi
.in
.PP
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:
.PP
.in +0.5i
.nf
.ft CW
unix://$PCP_RUN_DIR/pmcd.socket:?compress
local://my/local/pmcd.socket:?user=otto&pass=blotto&compress
.ft R
.fi
.in
.PP
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
.BR 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://").
.PP
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
.IR $PCP_RUN_DIR/pmcd.socket .
.PP
.in +0.5i
.nf
.ft CW
unix://$PCP_RUN_DIR/pmcd.socket
unix:/$PCP_RUN_DIR/pmcd.socket
unix:$PCP_RUN_DIR/pmcd.socket
.ft R
.fi
.in
.PP
Refer to
.BR __pmParseHostSpec (3)
for further details of the host and proxy host components.
.PP
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").
.PP
.B __pmParseHostAttrsSpec
takes a null-terminated host-and-attributes specification
.B string
and returns an array of 
.B pmHostSpec
structures, where the array has
.B count
entries, and an
.B attrs
hash table containing any attributes (including the
optional protocol, if it was specified).
.PP
Full details of the
.B pmHostSpec
structures are provided in
.BR __pmParseHostSpec (3).
.PP
The
.B __pmHashCtl
structure that is filled out on return via
.BR attributes ,
represents each individual attribute in the specification
.B string
with any associated value.
It should be considered an opaque structure and should be zeroed
beforehand.
.PP
The returned hash table control structure can be iterated using
one of the supplied iteration mechanisms \-
.B __pmHashWalkCB
(a callback-based mechanism)
or
.B __pmHashWalk
(a simple procedural mechanism).
These provide access to the individual hash nodes, as
.B __pmHashNode
entries, which provide access to decoded attributes and their
(optional) values.
.PP
.nf
.ft CW
    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;
.fi
.PP
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.
.PP
.B __pmUnparseHostSpec
performs the inverse operation, creating a
.B string
representation from
.B hosts
and
.B attributes
structures.
The size of the supplied
.B string
buffer must be provided by the caller using the
.B size
parameter.
.SH "RETURN VALUE"
If the given
.B string
is successfully parsed
.B __pmParseHostAttrsSpec
returns zero.
In this case the dynamic storage allocated by
.B __pmParseHostAttrsSpec
can be released by calling
.B __pmFreeHostAttrsSpec
using the addresses returned from
.B __pmParseHostAttrsSpec
.P
Alternatively, the
.B hosts
and
.B attributes
memory can be freed separately, using
.BR __pmFreeHostSpec (3)
and
.BR __pmFreeAttrsSpec .
.P
.B __pmParseHostAttrsSpec
returns
.B PM_ERR_GENERIC
and a dynamically allocated error message string in
.BR errmsg ,
if the given
.B string
does not parse, and the user-supplied
.B errmsg
pointer is non-null.
Be sure to
.BR free (3C)
the error message string in this situation.
.PP
In the case of an error, both
.B hosts
and
.B attributes
are undefined.
In the case of success,
.B errmsg
is undefined.
.PP
On success
.B __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
.B \-E2BIG
will be returned.
.SH SEE ALSO
.BR pmcd (1),
.BR pmproxy (1),
.BR pmchart (1),
.BR __pmParseHostSpec (3),
.BR PMAPI (3)
and
.BR pmNewContext (3).