/*
 * Serial data replay program.
 *
 * This is designed to take captured serial-line data, logged by (or as
 *  if by) serialconsole's -vlog option, with lines that look like
 *
 *	1234567890.123456 <<< data\r\nhere\r\n
 *
 *  where the number is a seconds-and-microseconds timestamp such as is
 *  returned by gettimeofday(), the <<< is fixed syntax, and the data
 *  is a blob of data, with backslash escapes: \a \b \t \n \f \r \e \\
 *  and up-to-3-digit octal.  This replays it in real time, with all
 *  timing offset to preserve the relative timing of the data.  (Of
 *  course, the absolute timing cannot be preserved.)
 *
 * The logged data comes in on stdin; the replayed data appears on
 *  stdout.  These are presumed to be redirected appropriately.
 */

#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <strings.h>
#include <sys/time.h>

extern const char *__progname;

#define MAXLEN 256

static unsigned char rawtext[MAXLEN];
static int rawlen;
static unsigned char proctext[MAXLEN];
static int proclen;
static unsigned long long int tbase_in;
static unsigned long long int tbase_clk;

static void getline(void)
{
 int c;

 rawlen = 0;
 while (1)
  { c = getchar();
    if (c == EOF) exit(0);
    if (rawlen >= MAXLEN-1)
     { fprintf(stderr,"%s: input line overflow\n",__progname);
       exit(1);
     }
    if (c == '\n')
     { if ((rawlen > 0) && (rawtext[rawlen-1] == '\r')) rawlen --;
       rawtext[rawlen] = '\0';
       return;
     }
    rawtext[rawlen++] = c;
  }
}

static int getdata(const char *dp)
{
 int bq;
 int bql;
 unsigned char c;

 proclen = 0;
 bq = 0;
 while (*dp)
  { if (proclen >= MAXLEN-1)
     { fprintf(stderr,"%s: input data overflow\n",__progname);
       exit(1);
     }
    if (bq)
     { switch (*dp++)
	{ case 'a': c =  7; bq = 0; break;
	  case 'b': c =  8; bq = 0; break;
	  case 't': c =  9; bq = 0; break;
	  case 'n': c = 10; bq = 0; break;
	  case 'f': c = 12; bq = 0; break;
	  case 'r': c = 13; bq = 0; break;
	  case 'e': c = 27; bq = 0; break;
	  case '\\': c = '\\'; bq = 0; break;
	  case '0': c = (c << 3) | 0; break;
	  case '1': c = (c << 3) | 1; break;
	  case '2': c = (c << 3) | 2; break;
	  case '3': c = (c << 3) | 3; break;
	  case '4': c = (c << 3) | 4; break;
	  case '5': c = (c << 3) | 5; break;
	  case '6': c = (c << 3) | 6; break;
	  case '7': c = (c << 3) | 7; break;
	  default:
	     if (bql > 0)
	      { bq = 0;
		dp --;
		proctext[proclen++] = c;
		continue;
	      }
	     fprintf(stderr,"%s: bad input line (bad \\ escape): %.*s\n",__progname,rawlen,&rawtext[0]);
	     return(1);
	     break;
	}
       if (! bq)
	{ proctext[proclen++] = c;
	  continue;
	}
       bql ++;
       if (bql >= 3)
	{ bq = 0;
	  proctext[proclen++] = c;
	}
     }
    else
     { if (*dp == '\\')
	{ bq = 1;
	  c = 0;
	  bql = 0;
	  dp ++;
	}
       else
	{ proctext[proclen++] = *dp++;
	}
     }
  }
 if (bq)
  { if (bql)
     { proctext[proclen++] = c;
     }
    else
     { fprintf(stderr,"%s: bad input line (ends with \\): %.*s\n",__progname,rawlen,&rawtext[0]);
       return(1);
     }
  }
 return(0);
}

int main(void);
int main(void)
{
 unsigned long int sec;
 unsigned long int usec;
 char *lp;
 char *ep;
 unsigned long long int t;
 struct timeval nowtv;
 unsigned long long int tc;

 tbase_clk = 0;
 while (1)
  { getline();
    lp = (void *)&rawtext[0];
    sec = strtoul(lp,&ep,10);
    if (lp == ep)
     { fprintf(stderr,"%s: bad input line (no tv_sec): %.*s\n",__progname,rawlen,&rawtext[0]);
       continue;
     }
    if (*ep != '.')
     { fprintf(stderr,"%s: bad input line (dot isn't): %.*s\n",__progname,rawlen,&rawtext[0]);
       continue;
     }
    lp = ep + 1;
    usec = strtoul(lp,&ep,10);
    if (lp == ep)
     { fprintf(stderr,"%s: bad input line (no tv_usec): %.*s\n",__progname,rawlen,&rawtext[0]);
       continue;
     }
    if (usec >= 1000000UL)
     { fprintf(stderr,"%s: bad input line (tv_usec out of range): %.*s\n",__progname,rawlen,&rawtext[0]);
       continue;
     }
    t = (sec * 1000000ULL) + usec;
    if (strncmp(ep," <<< ",5))
     { fprintf(stderr,"%s: bad input line (<<< isn't): %.*s\n",__progname,rawlen,&rawtext[0]);
       continue;
     }
    if (getdata(ep+5)) continue;
    gettimeofday(&nowtv,0);
    tc = (nowtv.tv_sec * 1000000ULL) + nowtv.tv_usec;
    if (tbase_clk == 0)
     { tbase_in = t;
       tbase_clk = tc;
     }
    if (tc < (tbase_clk + t - tbase_in))
     { struct timespec ts;
       unsigned long long int d;
       d = tbase_clk + t - tbase_in - tc;
       ts.tv_sec = d / 1000000ULL;
       ts.tv_nsec = (d % 1000000ULL) * 1000ULL;
       nanosleep(&ts,0);
     }
    write(1,&proctext[0],proclen);
  }
}