RossComputerGuy/stardustos

/**
 * StardustOS libc - (C) 2019 Tristan Ross
 */
#include <errno.h>
#include <malloc.h>
#include <stdio.h>

int vfprintf(FILE* stream, const char* format, va_list ap) {
    if (stream == NULL) {
        errno = EINVAL;
        return -1;
    }
    if (stream->write == NULL) {
        errno = ENOSYS;
        return -1;
    }
    va_list tmpap;
    va_copy(tmpap, ap);
    char tmp;
    int r = vsnprintf(&tmp, 1, format, tmpap);
    if (r < 0) {
        va_end(tmpap);
        return r;
    }
    char* str = malloc(r);
    if (str == NULL) return r;
    vsnprintf(str, r, format, ap);
    r = stream->write(stream, str, r);
    if (r > 0) stream->offset += r;
    free(str);
    va_end(tmpap);
    va_end(ap);
    return r;
}