NAME
upscli_get - retrieve data from a UPS
SYNOPSIS
#include <upsclient.h>
int upscli_get(UPSCONN *ups, int numq, const char **query,
int *numa, char ***answer)
DESCRIPTION
The upscli_get() function takes the pointer ups to a UPSCONN state
structure, and the pointer query to an array of numq query elements.
It builds a properly-formatted request from those elements and
transmits it to upsd(8).
Upon success, the response will be split into separate components. A
pointer to those components will be returned in answer. The number of
usable answer components will be returned in numa.
USES
This function implements the "GET" command in the protocol. As a
result, you can use it to request many different things from the
server. Some examples are:
- GET NUMLOGINS <ups>
- GET UPSDESC <ups>
- GET VAR <ups> <var>
- GET TYPE <ups> <var>
- GET DESC <ups> <var>
- GET CMDDESC <ups> <cmd>
QUERY FORMATTING
To generate a request for "GET NUMLOGINS su700", you would populate
query and numq as follows:
int numq;
const char *query[2];
query[0] = "NUMLOGINS";
query[1] = "su700";
numq = 2;
All escaping of special characters and quoting of elements with spaces
is handled for you inside this function.
ANSWER FORMATTING
The raw response from upsd to the above query would be "NUMLOGINS su700
1". Since this is split up for you, the values work out like this:
numa = 3;
answer[0] = "NUMLOGINS"
answer[1] = "su700"
answer[2] = "1"
Notice that the value which you seek typically starts at answer[numq].
ERROR CHECKING
This function will check your query against the response from upsd.
For example, if you send "VAR" "su700" "ups.status", it will expect to
see those at the beginning of the response.
If the results from upsd do not pass this case-insensitive test against
your request, this function will return an error. When this happens,
upscli_upserror(3) will return UPSCLI_ERR_PROTOCOL.
ANSWER ARRAY LIFETIME
The pointers contained within the answer array are only valid until the
next call to a upsclient function which references them. If you need
to use data from multiple calls, you must copy it somewhere else first.
The answer array and its elements may change locations, so you must not
rely on previous addresses. You must only use the addresses which were
returned by the most recent call. You also must not attempt to use
more than numa elements in answer. Such behavior is undefined, and may
yield bogus data or a crash.
The array will be deleted after calling upscli_disconnect(3). Any
access after that point is also undefined.
RETURN VALUE
The upscli_get() function returns 0 on success, or -1 if an error
occurs.
SEE ALSO
upscli_list_start(3), upscli_list_next(3), upscli_strerror(3),
upscli_upserror(3)
Mon Jan 22 2007