/*
 * tee - send a copy of stdin to a file as well as stdout.
 *
 * Version 1.1 and later by Devin Reade <gdr@myrias.ab.ca>
 *
 * tee originally appeared with Gno v1.x, but was fully buffered.
 * This is a complete re-write which uses full buffering for the
 * output file, but _no_ buffering on stdin and stdout.
 *
 * $Id: tee.c,v 1.2 1996/09/03 03:56:07 gdr Exp $
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h>
#include "getopt.h"

#ifdef CHECK_STACK
void begin_stack_check(void);
int end_stack_check(void);

#define STACKSTART begin_stack_check()
#define STACKEND(n) { \
  fprintf(stderr,"stack usage: %d bytes\n",end_stack_check()); \
  return n; \
}
#else
#define STACKSTART
#define STACKEND(n) return n
#endif

#define BUFFERSIZE 512
#define USAGE { \
  fprintf(stderr,"%s %s\nUsage:\t%s %s\n",argv[0],versionstr,argv[0], \
          usagestr); \
  STACKEND(-1); \
}

char *versionstr = "version 1.2 by Devin Reade";
char *usagestr = "[ -abiV ] filename\n\
\t-a\tappend to filename\n\
\t-i\tignore SIGINT\n";

char buf2[BUFFERSIZE];

int
main(int argc, char **argv)
{
  int c, b_flag;
  char *mode, buf;
  FILE *fp, *fp2;
  extern int optind;

  /*
   * initialization 
   */
  STACKSTART;
  mode = "w+";
  b_flag = 0;

  /*
   * parse the command line 
   */
  while ((c = getopt(argc, argv, "abiV")) != EOF) {
    switch (c) {
    case 'a':
      /* append to instead of truncate output file */
      mode = "a+";
      break;

    case 'b':
      /* do line buffering */
      b_flag++;
      break;

    case 'i':
      /* ignore SIGINT */
      signal(SIGINT, SIG_IGN);
      break;

    case 'V':
      /* FALLTHROUGH */
    default:
      USAGE;
      /* NOTREACHED */
    }
  }
  if ((argc - optind) < 1) {
    USAGE;
  }
  /*
   * open the output file 
   */
  if ((fp = fopen(argv[optind], mode)) == NULL) {
    perror("opening master file");
    STACKEND(1);
  }
  /*
   * loop until done with the first file 
   */
  if (b_flag) {
    /* line buffering */
    int done = 0;

    while (!done) {
      c = fread(buf2, sizeof(char), BUFFERSIZE, stdin);

      if (c == 0) {
	if (ferror(stdin)) {
	  fclose(fp);
	  STACKEND(1);
	  /* NOTREACHED */
	}
	done = 1;
      }
      fwrite(buf2, sizeof(char), c, stdout);
      fwrite(buf2, sizeof(char), c, fp);
    }
  } else {
    /* no buffering */
    int done = 0;

    while (!done) {
      switch (read(STDIN_FILENO, &buf, 1)) {
      case -1:
	fclose(fp);
	STACKEND(1);
	/* NOTREACHED */
      case 0:
	done = 1;
	break;
      default:
	write(STDOUT_FILENO, &buf, 1);
	fputc(buf, fp);
	break;
      }
    }
  }

  /*
   * make additional copies if necessary 
   */
  optind++;
  if (argc <= optind) {
    fclose(fp);
    STACKEND(0);
  }
  while (argc > optind) {
    size_t count;

    /* rewind the master file */
    rewind(fp);

    /* open the new file */
    if ((fp2 = fopen(argv[optind], mode)) == NULL) {
      perror("opening duplicate file");
      fclose(fp);
      STACKEND(1);
    }
    /* make the copy */
    while (!feof(fp) && !(ferror(fp))) {
      count = fread(buf2, sizeof(char), BUFFERSIZE, fp);

      if (count > 0) {
	fwrite(buf2, sizeof(char), count, fp2);

	if (ferror(fp2)) {
	  perror("writing duplicate file");
	  fclose(fp);
	  fclose(fp2);
	  STACKEND(1);
	}
      }
    }
    fclose(fp2);
    if (ferror(fp)) {
      perror("reading master file");
      fclose(fp);
      STACKEND(1);
    }
    optind++;
  }
  fclose(fp);
  STACKEND(0);
}