/*******
 * ts.c
 *
 * Tiny timestamping filter for line-based output, written by
 * Jonas Anden <jonas@anden.nu>. You may use it for whatever you
 * like as long as this header is retained. But don't blame
 * me if it breaks anything ;)
 *
 *  // J
 *
 *******/

#define MAXLINELEN 1024

#include <stdio.h>
#include <time.h>
#include <string.h>

/*
 * Compile with:
 * gcc -Wall -o ts ts.c
 *
 * Sample use:
 * $ (for i in `seq 1 10`; do echo "Line $i"; sleep 1; done) | ./ts '%H:%m:%S [%%s] <- On a %A'
 * 21:03:23 [Line 1] <- On a Tuesday
 * 21:03:24 [Line 2] <- On a Tuesday
 * 21:03:25 [Line 3] <- On a Tuesday
 * 21:03:26 [Line 4] <- On a Tuesday
 * 21:03:27 [Line 5] <- On a Tuesday
 * 21:03:28 [Line 6] <- On a Tuesday
 * 21:03:29 [Line 7] <- On a Tuesday
 * 21:03:30 [Line 8] <- On a Tuesday
 * 21:03:31 [Line 9] <- On a Tuesday
 * 21:03:32 [Line 10] <- On a Tuesday
 *
 */
int main( int argc, char *argv[] )
{
  time_t t;
  struct tm *tmp;
  int buflen;
  char buf[MAXLINELEN],
       tbuf[MAXLINELEN];

  if( argc != 2)
  {
    printf( "Usage:\n cat stream | %s <format> | cat > timestamped-stream\nformat is a date(1) compatible time format with\na %%%%s where you want the input line. Example: %s \"%%H:%%m:%%S [%%%%s] <- On a %%A\"\n\nWARNING: Due to the inherent format string \"vulnerability\",\n         DO NOT make this a setuid binary.\n", argv[0], argv[0] );
    return 1;
  }

  while( !feof( stdin ) )
  {
    if( fgets(buf, MAXLINELEN, stdin) == NULL )
      break;
    buflen=strlen(buf);
    t = time(NULL);
    tmp = localtime(&t);
    if( strftime(tbuf, MAXLINELEN, argv[1], tmp) == 0 )
      break;
    if( buf[buflen-1] == '\n' )
      buf[buflen-1] = 0;
    printf( tbuf, buf );
    putchar('\n');
    fflush(stdout);
  }
  return 0;
}