fixbmp

fixbmp.c

// Usage: prog input_file output_file
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main(int c, char** v) {
    FILE* in = fopen(v[1], "r");
    fseek(in, 0, SEEK_END);
    size_t off = ftell(in);
    rewind(in);
    char *arr = (char*)malloc(off);
    fread(arr, 1, off, in);
    fclose(in);
    for (size_t l = 54; l < off; l += 4) {
        char tmp;
        tmp = arr[l];
        arr[l] = arr[l+3];
        arr[l+3] = tmp;

        tmp = arr[l+1];
        arr[l+1] = arr[l+2];
        arr[l+2] = tmp;
    }

    FILE *out = fopen(v[2], "w");
    fwrite(arr, 1, off, out);
    fclose(out);

    return 0;
}