/*
 gifaddcomment 
 Copyright 2005 Ray Morris <support@webmastersguide.com>
 Released under GPL.
 usage: in.gif out.gif "New comment"

 Compile with:
 gcc -Wall -o gifaddcomment gifaddcomment.c
*/


#include <string.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc, char **argv)
{
        FILE *file;
        int c;
        FILE *out;

        if (argc < 3) {
            fprintf(stderr, "usage:\n%s in.gif out.gif \"New comment\"\n\n", argv[0]);
            exit(EXIT_FAILURE);
        }
                                                                                                    

        file = fopen(argv[1], "r");
        if (file == NULL) {
            perror(*argv);
            exit(EXIT_FAILURE);
        }

        out = fopen(argv[2], "w");
        if (file == NULL) {
            perror(*argv);
            exit(EXIT_FAILURE);
        }

        
        while ((c = getc(file)) != EOF) {
            putc(c, out);
        }

        fseek(out, -1, SEEK_END);
        putc(0x21, out);
        putc(0xFE, out);
        putc(strlen(argv[3]), out); // size of comment
        fwrite(argv[3], strlen(argv[3]), 1, out);  // 1 is how many
        putc(0, out);
        putc(0x3B, out);

        fclose(file);
        fclose(out);
        
        fflush(stdout);
        
        return(EXIT_SUCCESS);
}