binary_editor.c

#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <unistd.h>

int main(int argc, char* argv[]) {
	if(argc<2) {
		printf("Usage: %s outputfile\n", argv[0]);
		return 1;
	}

	FILE *output = fopen(argv[1], "wb");
	if(!output) {
		fprintf(stderr, "Cannot open file %s for writing\n");
		return 2;
	}

	int bitsToWrite = 0;
	char *memory = malloc(sizeof(char)*1+1);
	memory[0] = 0x00;
	static struct termios oldt,newt;
	
	tcgetattr(STDIN_FILENO, &oldt);
	newt = oldt;
	newt.c_lflag &= ~(ICANON|ECHO);
    tcsetattr(STDIN_FILENO, TCSANOW, &newt);

	char c, counter = 0, oldsize=1;
	while((c=getchar())!='\n') {
		if(c=='1'||c=='0') {
			putchar(c);
			memory[counter/8] |= ((c-'0'? 1 : 0)<<(7-counter%8));
			counter++;
			if(counter/8==oldsize) {
				oldsize++;
				char *backup = realloc(memory, sizeof(char)*oldsize+1);
				if(backup==NULL) {
					fprintf(stderr, "Not enough memory for operation!\n");
					return 3;
				}
				memory=backup;
			}
			if(counter%8==0) putchar(' ');
		} else if(c==8||c==127) {
			putchar(8);
			putchar(' ');
			putchar(8);
			counter--;
			if(counter/8+1<oldsize) {
				putchar(8);
				oldsize--;
				char *backup = realloc(memory, sizeof(char)*oldsize+1);
				if(backup==NULL) {
					fprintf(stderr, "Not enough memory for operation!\n");
					return 3;
				}
				memory=backup;
			}
			memory[counter/8] &= ~(1<<(7-counter%8)); 
		}
	}
	printf("\nSaving to file %s\n", argv[1]);
	fwrite(memory, sizeof(char), counter%8==0? oldsize-1 : oldsize, output);

	tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
	fclose(output);
	free(memory);
	return 0;
}