Create netledPi.c
A network activity light for the Raspberry Pi, using an LED connected to a GPIO pin.
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Ragnar Jensen
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2f37b3ddd0
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235
netledPi.c
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235
netledPi.c
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/ **************************************************************************
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*
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* A network activity light for the Raspberry Pi, using an LED connected to a GPIO pin.
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* Based on hddled.c - http://members.optusnet.com.au/foonly/whirlpool/code/hddled.c -
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* This program uses the WiringPi library by Gordon Henderson - http://wiringpi.com/ - Thanks, Gordon!
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*
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*
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* To compile:
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* gcc -Wall -O3 -o netledPi netledPi.c -lwiringPi
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*
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* Options:
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* -d, --detach Detach from terminal (become a daemon)
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* -p, --pin=VALUE GPIO pin (using wiringPi numbering scheme) where LED is connected (default: 11)
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* -r, --refresh=VALUE Refresh interval (default: 20 ms)
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*
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* GPIO pin ----|>|----[330]----+
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* LED |
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* ===
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* Ground
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*
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* Default LED Pin - wiringPi pin 11 is BCM_GPIO 7, physical pin 25 on the Pi's P1 header.
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* Note: This pin is also used for the SPI interface. If you have SPI add-ons connected,
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* you'll have to use the -p option to change it to another, unused pin.
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*/
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#define NETDEVICES "/proc/net/dev"
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#define _GNU_SOURCE
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#include <argp.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <wiringPi.h>
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static unsigned int o_refresh = 20; /* milliseconds */
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static unsigned int o_gpiopin = 11; /* wiringPi numbering scheme */
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static int o_detach = 0;
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static volatile sig_atomic_t running = 1;
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static char *line = NULL;
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static size_t len = 0;
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/* Reread the netdevices file */
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int activity(FILE *netdevices) {
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static unsigned int prev_inpackets, prev_outpackets;
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unsigned int inpackets, outpackets;
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unsigned int device_inpackets, device_outpackets;
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int found_inpackets, found_outpackets;
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int result;
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char *ptr;
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char device[8];
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/* Go to the beginning of the netdevices file */
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result = TEMP_FAILURE_RETRY(fseek(netdevices, 0L, SEEK_SET));
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if (result) {
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perror("Could not rewind " NETDEVICES);
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return result;
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}
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/* Clear glibc's buffer */
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result = TEMP_FAILURE_RETRY(fflush(netdevices));
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if (result) {
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perror("Could not flush input stream");
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return result;
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}
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/* Extract the I/O stats */
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inpackets = outpackets = 0;
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found_inpackets = found_outpackets = 0;
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device_inpackets = device_outpackets = 0;
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while (getline(&line, &len, netdevices) != -1 && errno != EINTR) {
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ptr = line;
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while (*ptr == ' ') ptr++; // Skip leading spaces
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if (sscanf(ptr, "%s %*u %u %*u %*u %*u %*u %*u %*u %*u %u %*u %*u %*u %*u %*u %*u", device, &device_inpackets, &device_outpackets)) {
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if(strstr(device, "lo:")) continue; // Skip loopback interface
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found_inpackets++;
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found_outpackets++;
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inpackets += device_inpackets;
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outpackets += device_outpackets;
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}
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}
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if (!found_inpackets || !found_outpackets) {
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fprintf(stderr, "Could not find required lines in " NETDEVICES);
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return -1;
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}
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/* Anything changed? */
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result = (prev_inpackets != inpackets) ||
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(prev_outpackets != outpackets);
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prev_inpackets = inpackets;
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prev_outpackets = outpackets;
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return result;
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}
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/* Update the LED */
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void led(int on) {
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static int current = 1; /* Ensure the LED turns off on first call */
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if (current == on)
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return;
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if (on) {
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digitalWrite (o_gpiopin, HIGH);
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} else {
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digitalWrite (o_gpiopin, LOW);
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}
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current = on;
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}
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/* Signal handler -- break out of the main loop */
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void shutdown(int sig) {
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running = 0;
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}
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/* Argp parser function */
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error_t parse_options(int key, char *arg, struct argp_state *state) {
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switch (key) {
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case 'd':
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o_detach = 1;
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break;
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case 'r':
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o_refresh = strtol(arg, NULL, 10);
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if (o_refresh < 10)
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argp_failure(state, EXIT_FAILURE, 0,
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"refresh interval must be at least 10");
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break;
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case 'p':
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o_gpiopin = strtol(arg, NULL, 10);
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if ((o_gpiopin < 0) || (o_gpiopin > 29))
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argp_failure(state, EXIT_FAILURE, 0,
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"pin number must be between 0 and 29");
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break;
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}
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return 0;
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}
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int main(int argc, char **argv) {
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struct argp_option options[] = {
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{ "detach", 'd', NULL, 0, "Detach from terminal" },
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{ "pin", 'p', "VALUE", 0, "GPIO pin where LED is connected (default: wiringPi pin 11, physical pin 25 on the P1 header)" },
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{ "refresh", 'r', "VALUE", 0, "Refresh interval (default: 20 ms)" },
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{ 0 },
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};
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struct argp parser = {
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NULL, parse_options, NULL,
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"Show network activity using an LED wired to a GPIO pin.",
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NULL, NULL, NULL
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};
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int status = EXIT_FAILURE;
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FILE *netdevices = NULL;
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struct timespec delay;
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/* Parse the command-line */
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parser.options = options;
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if (argp_parse(&parser, argc, argv, ARGP_NO_ARGS, NULL, NULL))
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goto out;
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delay.tv_sec = o_refresh / 1000;
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delay.tv_nsec = 1000000 * (o_refresh % 1000);
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wiringPiSetup () ;
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pinMode (o_gpiopin, OUTPUT) ;
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/* Open the netdevices file */
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netdevices = fopen(NETDEVICES, "r");
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if (!netdevices) {
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perror("Could not open " NETDEVICES " for reading");
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goto out;
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}
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/* Ensure the LED is off */
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led(LOW);
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/* Save the current I/O stat values */
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if (activity(netdevices) < 0)
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goto out;
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/* Detach from terminal? */
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if (o_detach) {
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pid_t child = fork();
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if (child < 0) {
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perror("Could not detach from terminal");
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goto out;
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}
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if (child) {
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/* I am the parent */
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status = EXIT_SUCCESS;
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goto out;
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}
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}
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/* We catch these signals so we can clean up */
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{
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struct sigaction action;
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memset(&action, 0, sizeof(action));
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action.sa_handler = shutdown;
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sigemptyset(&action.sa_mask);
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action.sa_flags = 0; /* We block on usleep; don't use SA_RESTART */
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sigaction(SIGHUP, &action, NULL);
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sigaction(SIGINT, &action, NULL);
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sigaction(SIGTERM, &action, NULL);
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}
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/* Loop until signal received */
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while (running) {
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int a;
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if (nanosleep(&delay, NULL) < 0)
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break;
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a = activity(netdevices);
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if (a < 0)
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break;
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led(a);
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}
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/* Ensure the LED is off */
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led(LOW);
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status = EXIT_SUCCESS;
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out:
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if (line) free(line);
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if (netdevices) fclose(netdevices);
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return status;
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}
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