08-06-2008
OK is yes, desirable is no
Unix will be ok with it, as long as the loops are not nested.
But... think of the next person who must work with the code. It can be difficult to track single letter variables - try doing a find for the letter a and see what I mean. Better to call it cnt, at the very least.
As far as unique names, again this is more of a preference for future editing or file error resolution. Thus, I will amend my previous from just cnt to cnt_1 or something similiar. That is quite easy to read, and any programmer would be able to follow.
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LEARN ABOUT NETBSD
pcap_breakloop
PCAP_BREAKLOOP(3) Library Functions Manual PCAP_BREAKLOOP(3)
NAME
pcap_breakloop - force a pcap_dispatch() or pcap_loop() call to return
SYNOPSIS
#include <pcap/pcap.h>
void pcap_breakloop(pcap_t *);
DESCRIPTION
pcap_breakloop() sets a flag that will force pcap_dispatch() or pcap_loop() to return rather than looping; they will return the number of
packets that have been processed so far, or -2 if no packets have been processed so far.
This routine is safe to use inside a signal handler on UNIX or a console control handler on Windows, as it merely sets a flag that is
checked within the loop.
The flag is checked in loops reading packets from the OS - a signal by itself will not necessarily terminate those loops - as well as in
loops processing a set of packets returned by the OS. Note that if you are catching signals on UNIX systems that support restarting system
calls after a signal, and calling pcap_breakloop() in the signal handler, you must specify, when catching those signals, that system calls
should NOT be restarted by that signal. Otherwise, if the signal interrupted a call reading packets in a live capture, when your signal
handler returns after calling pcap_breakloop(), the call will be restarted, and the loop will not terminate until more packets arrive and
the call completes.
Note also that, in a multi-threaded application, if one thread is blocked in pcap_dispatch(), pcap_loop(), pcap_next(), or pcap_next_ex(),
a call to pcap_breakloop() in a different thread will not unblock that thread; you will need to use whatever mechanism the OS provides for
breaking a thread out of blocking calls in order to unblock the thread, such as thread cancellation in systems that support POSIX threads.
Note that pcap_next() and pcap_next_ex() will, on some platforms, loop reading packets from the OS; that loop will not necessarily be ter-
minated by a signal, so pcap_breakloop() should be used to terminate packet processing even if pcap_next() or pcap_next_ex() is being used.
pcap_breakloop() does not guarantee that no further packets will be processed by pcap_dispatch() or pcap_loop() after it is called; at most
one more packet might be processed.
If -2 is returned from pcap_dispatch() or pcap_loop(), the flag is cleared, so a subsequent call will resume reading packets. If a posi-
tive number is returned, the flag is not cleared, so a subsequent call will return -2 and clear the flag.
SEE ALSO
pcap(3), pcap_loop(3), pcap_next_ex(3)
5 April 2008 PCAP_BREAKLOOP(3)