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fprintf(3) should not be used by signal handlers #752

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fprintf(3) should not be used by signal handlers #752

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53 changes: 34 additions & 19 deletions tcpdump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -217,8 +217,10 @@ static char *zflag = NULL; /* compress each savefile using a specified command
static int immediate_mode;
#endif

static int infodelay;
static int infoprint;
#ifndef _WIN32
static int gotalarm;
#endif /* _WIN32 */

char *program_name;

Expand Down Expand Up @@ -2387,6 +2389,9 @@ DIAG_ON_CLANG(assign-enum)
*/
struct itimerval timer;
(void)setsignal(SIGALRM, verbose_stats_dump);
alarm(1);
/* signal alarm to get the first iteration ASAP */
gotalarm = 1;
timer.it_interval.tv_sec = 1;
timer.it_interval.tv_usec = 0;
timer.it_value.tv_sec = 1;
Expand Down Expand Up @@ -2738,8 +2743,6 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s

++packets_captured;

++infodelay;

dump_info = (struct dump_info *)user;

/*
Expand Down Expand Up @@ -2941,9 +2944,18 @@ dump_packet_and_trunc(u_char *user, const struct pcap_pkthdr *h, const u_char *s
if (dump_info->ndo != NULL)
pretty_print_packet(dump_info->ndo, h, sp, packets_captured);

--infodelay;
if (infoprint)
if (infoprint) {
info(0);
infoprint = 0;
}

#ifndef _WIN32
if (gotalarm) {
fprintf(stderr, "Got %u\r", packets_captured);
gotalarm = 0;
alarm(1);
}
#endif /* !_WIN32 */
}

static void
Expand All @@ -2953,8 +2965,6 @@ dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)

++packets_captured;

++infodelay;

dump_info = (struct dump_info *)user;

pcap_dump((u_char *)dump_info->pdd, h, sp);
Expand All @@ -2966,33 +2976,38 @@ dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
if (dump_info->ndo != NULL)
pretty_print_packet(dump_info->ndo, h, sp, packets_captured);

--infodelay;
if (infoprint)
if (infoprint) {
info(0);
infoprint = 0;
}
}

static void
print_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
++packets_captured;

++infodelay;

pretty_print_packet((netdissect_options *)user, h, sp, packets_captured);

--infodelay;
if (infoprint)
if (infoprint) {
info(0);
infoprint = 0;
}

#ifndef _WIN32
if (gotalarm) {
fprintf(stderr, "Got %u\r", packets_captured);
gotalarm = 0;
alarm(1);
}
#endif /* !_WIN32 */
}

#ifdef SIGNAL_REQ_INFO
static void
requestinfo(int signo _U_)
{
if (infodelay)
++infoprint;
else
info(0);
infoprint = 1;
}
#endif

Expand All @@ -3010,7 +3025,7 @@ print_packets_captured (void)
{
static u_int prev_packets_captured, first = 1;

if (infodelay == 0 && (first || packets_captured != prev_packets_captured)) {
if (first || packets_captured != prev_packets_captured) {
fprintf(stderr, "Got %u\r", packets_captured);
first = 0;
prev_packets_captured = packets_captured;
Expand All @@ -3029,7 +3044,7 @@ static void CALLBACK verbose_stats_dump(PVOID param _U_,
#else /* _WIN32 */
static void verbose_stats_dump(int sig _U_)
{
print_packets_captured();
gotalarm = 1;
}
#endif /* _WIN32 */

Expand Down