Read from file ignoring EOF

gistfile1.c

int myfile_read_buffer(void *opaque, uint8_t *buf, int buf_size)
{
    MyFileContext *file = opaque;
    FILE *fd = file->file;
    
    void *b = malloc(buf_size);
    
    size_t bytes_left = buf_size;
    size_t total_bytes_read = 0;
    void *p = b;
    while (bytes_left > 0) {
        if (fd == NULL) {
            free(b);
            return total_bytes_read;
        }
        
        ssize_t bytes_read = fread(p, 1, bytes_left, fd);
        if (bytes_read < 0) {
            free(b);
            return bytes_read;
        }
        else if (bytes_read == 0) { // EOF - wait and repeat
            if (myfile_get_finished_writing(opaque)) {
                total_bytes_read += bytes_read;
                goto finish;
            }
            else {
                usleep(1000 * 100); // 100ms
                clearerr(fd);
                continue;
            }
        }
        
        total_bytes_read += bytes_read;
        p += bytes_read;
        bytes_left -= bytes_read;
    }
    
finish:
    memcpy(buf, b, total_bytes_read);
    free(b);
    return total_bytes_read;
}