Use setitimer() rather than alarm().

setitimer() can reload the timer, so we don't have to reload it in the
SIGALRM handler.  It's been in UN*X standards since UNIX 95.

diff --git a/tcpdump.c b/tcpdump.c
index 5973f327d43d3f11ba7a54dede90a51bae2bfdab..1be626b218d4b1fb3c0bf43fe7943fc4cca50ee9 100644 (file)
--- a/tcpdump.c
+++ b/tcpdump.c
@@ -98,6 +98,7 @@ The Regents of the University of California.  All rights reserved.\n";
 #include <string.h>
 #include <limits.h>
 #ifndef _WIN32
+#include <sys/time.h>
 #include <sys/wait.h>
 #include <sys/resource.h>
 #include <pwd.h>
@@ -2217,9 +2218,17 @@ DIAG_ON_CLANG(assign-enum)
                timer_id = timeSetEvent(1000, 100, verbose_stats_dump, 0, TIME_PERIODIC);
                setvbuf(stderr, NULL, _IONBF, 0);
 #else /* _WIN32 */
-               /* UN*X has alarm() */
+               /*
+                * Assume this is UN*X, and that it has setitimer(); that
+                * dates back to UNIX 95.
+                */
+               struct itimerval timer;
                (void)setsignal(SIGALRM, verbose_stats_dump);
-               alarm(1);
+               timer.it_interval.tv_sec = 1;
+               timer.it_interval.tv_usec = 0;
+               timer.it_value.tv_sec = 1;
+               timer.it_value.tv_usec = 1;
+               setitimer(ITIMER_REAL, &timer, NULL);
 #endif /* _WIN32 */
        }
 
@@ -2409,7 +2418,13 @@ cleanup(int signo _U_)
                timeKillEvent(timer_id);
        timer_id = 0;
 #else /* _WIN32 */
-       alarm(0);
+       struct itimerval timer;
+
+       timer.it_interval.tv_sec = 0;
+       timer.it_interval.tv_usec = 0;
+       timer.it_value.tv_sec = 0;
+       timer.it_value.tv_usec = 0;
+       setitimer(ITIMER_REAL, &timer, NULL);
 #endif /* _WIN32 */
 
 #ifdef HAVE_PCAP_BREAKLOOP
@@ -2840,7 +2855,6 @@ void CALLBACK verbose_stats_dump (UINT timer_id _U_, UINT msg _U_, DWORD_PTR arg
 static void verbose_stats_dump(int sig _U_)
 {
        print_packets_captured();
-       alarm(1);
 }
 #endif /* _WIN32 */