#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/*
 * Simple program that tails /var/log/tvlog, looking for a line containing
 * the string "LineupUpdate::DoUpdates() has completed" and that runs
 * channel_map to remap things back.
 */

#define PATH_TVLOG	"/var/log/tvlog"
#define PATH_REMAPPER	"/var/hack/bin/channel_map"

int main(int argc, char **argv)
{
    char buf[2048];
    struct stat sb, osb;
    FILE *fp;

    daemon(0, 0);

    for (;;) {
	fp = fopen(PATH_TVLOG, "r");
	if (fp == NULL) {
	    sleep(1);
	    continue;
	}
	/* stash stat info */
	if (fstat(fileno(fp), &osb) == -1) {
	    fclose(fp);
	    continue;
	}
	/* seek to end */
	fseek(fp, 0L, SEEK_END);

	for (;;) {
	    /* XXX - assumes string we are searching for will appear in a single write */
	    if (fgets(buf, sizeof(buf), fp) == NULL) {
		if (ferror(fp))
		    break;

		/* check to see if the file was replaced */
		if (stat(PATH_TVLOG, &sb) == 0) {
		    if (sb.st_ino != osb.st_ino || sb.st_size < osb.st_size)
			break;	/* replaced, re-open */
		}
		/* nothing to read yet, sleep and continue */
		clearerr(fp);
		sleep(1);
		continue;
	    }
	    if (strstr(buf, "LineupUpdate::DoUpdates() has completed")) {
		system(PATH_REMAPPER);
	    }
	}
	fclose(fp);
    }
}