/*
 * tee - send a copy of stdin to a file as well as stdout.
 *
 * Version 1.1 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.
 */

#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 1.1 by Devin Reade";
char *usagestr="[ -ai ] filename\n\
\t-a\tappend to filename\n\
\t-i\tignore SIGINT\n";

char buf2[BUFFERSIZE];

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

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

   /* parse the command line */
   while ((c = getopt(argc, argv, "aiV")) != EOF)
	   switch (c) {
      case 'a':
	      /* append to instead of truncate output file*/
	      mode = "a+";
         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 */
	for(;;) {
	   int done = 0;
	   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;
      }
      if (done) 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);
}