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Update signal handlers to use sigaction, and re-open logfile on SIGHUP to integrate logrotated support #268

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Update signal handlers to use sigaction, and re-open logfile on SIGHUP to integrate logrotated support #268

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204 changes: 167 additions & 37 deletions candump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -116,9 +116,18 @@ static const int canfd_on = 1;
static const char anichar[MAXANI] = { '|', '/', '-', '\\' };
static const char extra_m_info[4][4] = { "- -", "B -", "- E", "B E" };

#define MAXLOGNAMESZ 100
static FILE *logfile = NULL;
static char log_filename[MAXLOGNAMESZ];

static unsigned char silent = SILENT_INI;

extern int optind, opterr, optopt;

static volatile int running = 1;
static volatile int flag_reopen_file;
static int is_auto_log_name;
static volatile unsigned long sighup_count;

static void print_usage(char *prg)
{
Expand All @@ -133,7 +142,7 @@ static void print_usage(char *prg)
fprintf(stderr, " -a (enable additional ASCII output)\n");
fprintf(stderr, " -S (swap byte order in printed CAN data[] - marked with '%c' )\n", SWAP_DELIMITER);
fprintf(stderr, " -s <level> (silent mode - %d: off (default) %d: animation %d: silent)\n", SILENT_OFF, SILENT_ANI, SILENT_ON);
fprintf(stderr, " -l (log CAN-frames into file. Sets '-s %d' by default)\n", SILENT_ON);
fprintf(stderr, " -l <name> (log CAN-frames into file. Sets '-s %d' by default)\n", SILENT_ON);
fprintf(stderr, " -L (use log file format on stdout)\n");
fprintf(stderr, " -n <count> (terminate after reception of <count> CAN frames)\n");
fprintf(stderr, " -r <size> (set socket receive buffer to <size>)\n");
Expand Down Expand Up @@ -171,9 +180,16 @@ static void sigterm(int signo)
running = 0;
}

static int idx2dindex(int ifidx, int socket)
static void sighup(int signo)
{
if (signo == SIGHUP && running) {
flag_reopen_file = 1;
sighup_count++;
}
}

static int idx2dindex(int ifidx, int socket)
{
int i;
struct ifreq ifr;

Expand Down Expand Up @@ -221,6 +237,89 @@ static int idx2dindex(int ifidx, int socket)
return i;
}

static int sprint_auto_filename_format(char *buffer)
{
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(char *buffer)

time_t currtime;
struct tm now;

if (time(&currtime) == (time_t)-1) {
perror("time");
return 1;
}

localtime_r(&currtime, &now);

sprintf(buffer, "candump-%04d-%02d-%02d_%02d%02d%02d.log",
now.tm_year + 1900,
now.tm_mon + 1,
now.tm_mday,
now.tm_hour,
now.tm_min,
now.tm_sec);

fprintf(stderr, "Enabling Logfile '%s'\n", buffer);

return 0;
}

/* opens file using global var logfile */
static int open_log_file(const char *file_name)
{
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(const char *file_name)

if (silent != SILENT_ON)
fprintf(stderr, "Warning: Console output active while logging!\n");

logfile = fopen(file_name, "w");

if (!logfile) {
perror("logfile");
return 1;
}

return 0;
}

static int reopen_file(FILE *file_handle)
{
const char *fopen_opts = (sighup_count > 0 && !is_auto_log_name) ? "a" : "w";

if (!file_handle)
return 1;

if (is_auto_log_name == 1) {
const int errcode = sprint_auto_filename_format(log_filename);

if (errcode != 0) {
return 1;
}
}

/* close existing filehandle, and open new one if necessary */
logfile = freopen(log_filename, fopen_opts, file_handle);

flag_reopen_file = 0;

return logfile == 0;
}

static int process_logname_arg(const char *arg)
{
if (arg != 0) {
const size_t len = strnlen(arg, MAXLOGNAMESZ);

if (len > 0 && len < MAXLOGNAMESZ) {
strncpy(log_filename, arg, MAXLOGNAMESZ - 1);
} else {
return 1;
}
is_auto_log_name = 0;
} else {
is_auto_log_name = 1;
sprint_auto_filename_format(log_filename);
}

return 0;
}

int main(int argc, char **argv)
{
int fd_epoll;
Expand All @@ -233,7 +332,7 @@ int main(int argc, char **argv)
unsigned char down_causes_exit = 1;
unsigned char dropmonitor = 0;
unsigned char extra_msg_info = 0;
unsigned char silent = SILENT_INI;

unsigned char silentani = 0;
unsigned char color = 0;
unsigned char view = 0;
Expand All @@ -257,16 +356,32 @@ int main(int argc, char **argv)
struct ifreq ifr;
struct timeval tv, last_tv;
int timeout_ms = -1; /* default to no timeout */
FILE *logfile = NULL;

signal(SIGTERM, sigterm);
signal(SIGHUP, sigterm);
signal(SIGINT, sigterm);
sigset_t sig_block_mask;
sigset_t sig_empty_mask;
struct sigaction sighup_action = { .sa_flags = SA_RESTART };
struct sigaction sigterm_action = { .sa_flags = SA_RESTART, .sa_handler = sigterm };

sigfillset(&sig_block_mask);
sighup_action.sa_mask = sig_block_mask;
sigemptyset(&sig_empty_mask);
sigterm_action.sa_mask = sig_empty_mask;

sigaction (SIGHUP, &sigterm_action, NULL);
sigaction (SIGINT, &sigterm_action, NULL);

last_tv.tv_sec = 0;
last_tv.tv_usec = 0;

while ((opt = getopt(argc, argv, "t:HciaSs:lDdxLn:r:he8T:?")) != -1) {
int getoptargc = argc;

/* Since interface is a required argument, we don't need to parse opt for final arg
* This enabled the -l option to take an optional filename */
if (getoptargc > 0) {
getoptargc = argc - 1;
}

while ((opt = getopt(getoptargc, argv, ":t:HciaSs:l:DdxLn:r:he8T:?")) != -1) {
switch (opt) {
case 't':
timestamp = optarg[0];
Expand Down Expand Up @@ -314,9 +429,32 @@ int main(int argc, char **argv)
}
break;

case ':': //handle flags with optional values

switch (optopt)
{
case 'l':
log = 1;

if (process_logname_arg(optarg) != 0) {
print_usage(basename(argv[0]));
exit(1);
}
break;
default:
fprintf(stderr, "option -%c is missing a required argument\n", optopt);
return EXIT_FAILURE;
}
break;

case 'l':
log = 1;

if (process_logname_arg(optarg) != 0) {
is_auto_log_name = 0;
print_usage(basename(argv[0]));
exit(1);
}
Comment on lines +433 to +457
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@hartkopp hartkopp Dec 7, 2020 •
edited
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Can you please think about an integration into a logrotated configuration, that can cope with the assumptions:

  1. The option '-l' remains untouched
  2. The logfile is closed and a new logfile is opened with a new date-generated filename

So no re-open/append stuff and no change with the naming.
You might also execute candump in /tmp/candump/ to place the files there for logrotation post-processing.

I'm fine with creating two file splitting triggers about the length and the SIGHUP. But the current approach just adds too much complexity that does not need to be inside candump.

break;

case 'D':
Expand Down Expand Up @@ -371,6 +509,10 @@ int main(int argc, char **argv)
exit(0);
}

/* Configure SIGHUP handler to reopen file if logging */
sighup_action.sa_handler = log ? sighup : sigterm;
sigaction(SIGHUP, &sighup_action, NULL);

if (logfrmt && view) {
fprintf(stderr, "Log file format selected: Please disable ASCII/BINARY/SWAP/RAWDLC options!\n");
exit(0);
Expand Down Expand Up @@ -592,35 +734,10 @@ int main(int argc, char **argv)
}

if (log) {
time_t currtime;
struct tm now;
char fname[83]; /* suggested by -Wformat-overflow= */
const int result = open_log_file(log_filename);

if (time(&currtime) == (time_t)-1) {
perror("time");
if (result != 0)
return 1;
}

localtime_r(&currtime, &now);

sprintf(fname, "candump-%04d-%02d-%02d_%02d%02d%02d.log",
now.tm_year + 1900,
now.tm_mon + 1,
now.tm_mday,
now.tm_hour,
now.tm_min,
now.tm_sec);

if (silent != SILENT_ON)
fprintf(stderr, "Warning: Console output active while logging!\n");

fprintf(stderr, "Enabling Logfile '%s'\n", fname);

logfile = fopen(fname, "w");
if (!logfile) {
perror("logfile");
return 1;
}
}

/* these settings are static and can be held out of the hot path */
Expand All @@ -631,10 +748,17 @@ int main(int argc, char **argv)
msg.msg_control = &ctrlmsg;

while (running) {

if ((num_events = epoll_wait(fd_epoll, events_pending, currmax, timeout_ms)) <= 0) {
//perror("epoll_wait");
running = 0;
if(num_events == -1) {
const int serr = errno;
if (log && flag_reopen_file && serr == EINTR) {
if (reopen_file(logfile) != 0)
return -1;
} else {
running = 0;
}
}
continue;
}

Expand Down Expand Up @@ -817,6 +941,12 @@ int main(int argc, char **argv)
out_fflush:
fflush(stdout);
}

if (log && flag_reopen_file == 1) {
if (reopen_file(logfile) != 0) {
return -1;
}
}
}

for (i = 0; i < currmax; i++)
Expand Down