11-25-2012
Here are the first reasons that come to mind:
- easily detect bogus code that reference unallocated memory
- avoid exhausting the system virtual memory for those operating systems that do not overcommit memory
- allow non heap memory to exist, eg. allow a new thread to get its own stack
- allow libraries that manage memory allocation (like libc malloc/free) to know what part of memory they own so can use the way they like.
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LEARN ABOUT OPENSOLARIS
upscli_list_start
UPSCLI_LIST_START(3) NUT Manual UPSCLI_LIST_START(3)
NAME
upscli_list_start - begin multi-item retrieval from a UPS
SYNOPSIS
#include <upsclient.h>
int upscli_list_start(UPSCONN_t *ups, int numq, const char **query)
DESCRIPTION
The upscli_list_start() function takes the pointer ups to a UPSCONN_t 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 caller must call upscli_list_next(3) to retrieve the elements of the list. Failure to retrieve the list will most likely
result in the client getting out of sync with the server due to buffered data.
USES
This function implements the "LIST" command in the protocol. As a result, you can use it to request many different things from the server.
Some examples are:
o LIST UPS
o LIST VAR <ups>
o LIST RW <ups>
o LIST CMD <ups>
o LIST ENUM <ups> <var>
o LIST RANGE <ups> <var>
QUERY FORMATTING
To see the list of variables on a UPS called su700, the protocol command would be LIST VAR su700. To start that list with this function,
you would populate query and numq as follows:
int numq;
const char *query[2];
query[0] = "VAR";
query[1] = "su700";
numq = 2;
All escaping of special characters and quoting of elements with spaces are handled for you inside this function.
ERROR CHECKING
This function checks the response from upsd(8) against your query. If it is not starting a list, or is starting the wrong type of list, it
will return an error code.
When this happens, upscli_upserror(3) will return UPSCLI_ERR_PROTOCOL.
RETURN VALUE
The upscli_list_start() function returns 0 on success, or -1 if an error occurs.
SEE ALSO
upscli_fd(3), upscli_get(3), upscli_readline(3), upscli_sendline(3), upscli_ssl(3), upscli_strerror(3), upscli_upserror(3)
Network UPS Tools 05/31/2012 UPSCLI_LIST_START(3)