/*
 * Program that combines echo-test and copy-file:
 *
 * With no command-line arguments, echoes text from stdin to stdout.
 * 
 * With two command-line arguments (infile and outfile), copies infile
 * to outfile.
 *
 * Otherwise prints error message.
 */
#include <stdio.h>

void copy_file(FILE * infile, FILE * outfile);

int main(int argc, char *argv[]) {
	if (argc == 1) {
		fprintf(stderr, "enter text, control-D to end\n");
		copy_file(stdin, stdout);
	}
	else if (argc == 3) { 
		FILE * instream = fopen(argv[1], "r");
		if (instream == NULL) { 
			fprintf(stderr, "cannot open file %s\n", argv[1]);
			return 1;
		}
		FILE * outstream = fopen(argv[2], "w");
		if (outstream == NULL) { 
			fprintf(stderr, "cannot open file %s\n", argv[2]);
			return 1;
		}
		copy_file(instream, outstream);
		fclose(instream);
		fclose(outstream);
	}
	else {
		fprintf(stderr, "usage:  %s infile outfile\n", argv[0]);
		return 1;
	}
}

void copy_file(FILE * infile, FILE * outfile) {
	int ch;
	int count = 0;
	while ((ch = fgetc(infile)) != EOF) {
		fputc(ch, outfile);
		count += 1;
	}
	fprintf(stderr, "%d characters copied\n", count);
}