Ghi an toàn và xử lý lỗi

FILE *f = fopen("du-lieu.dat", "wb");    /* tep cu bi xoa NGAY tai day */

for (size_t i = 0; i < n; ++i)
    ghi_ban_ghi(f, &ds[i]);              /* mat vai giay voi du lieu lon */

fclose(f);

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

int luu_an_toan(const char *ten, const SinhVien *ds, size_t n) {
    char tam[512];

    int k = snprintf(tam, sizeof tam, "%s.tmp", ten);
    if (k < 0 || (size_t)k >= sizeof tam) return -1;      /* ten qua dai */

    FILE *f = fopen(tam, "wb");
    if (!f) { perror(tam); return -1; }

    /* Tu day tro di, moi that bai deu phai XOA TEP TAM */
    for (size_t i = 0; i < n; ++i)
        if (ghi_ban_ghi(f, &ds[i]) != 0) goto hong;

    if (fflush(f) != 0) goto hong;

    if (fclose(f) != 0) {                 /* fclose that bai: dung goto vi
                                             f da khong con hop le */
        remove(tam);

        return -1;
    }

    /* Tren Windows, rename khong ghi de duoc tep da ton tai */
    remove(ten);

    if (rename(tam, ten) != 0) {
        perror("rename");
        remove(tam);

        return -1;
    }

    return 0;

hong:
    fclose(f);
    remove(tam);

    return -1;
}

#include <unistd.h>       /* fsync   */
#include <fcntl.h>        /* open    */

int luu_that_an_toan(const char *ten, const SinhVien *ds, size_t n) {
    char tam[512];
    snprintf(tam, sizeof tam, "%s.tmp", ten);

    FILE *f = fopen(tam, "wb");
    if (!f) return -1;

    for (size_t i = 0; i < n; ++i)
        if (ghi_ban_ghi(f, &ds[i]) != 0) { fclose(f); remove(tam); return -1; }

    /* 1. Bo dem thu vien -> nhan he dieu hanh */
    if (fflush(f) != 0)          { fclose(f); remove(tam); return -1; }

    /* 2. Bo dem nhan -> mat dia */
    if (fsync(fileno(f)) != 0)   { fclose(f); remove(tam); return -1; }

    if (fclose(f) != 0)          { remove(tam); return -1; }

    /* 3. Doi ten */
    if (rename(tam, ten) != 0)   { remove(tam); return -1; }

    /* 4. Ban ghi ve TEN TEP nam trong thu muc, cung can dong bo */
    int td = open(thu_muc_cua(ten), O_RDONLY);

    if (td >= 0) { fsync(td); close(td); }

    return 0;
}

MaLoi m = ql_luu(&ql, ten);

if (m != QL_OK) {
    fprintf(stderr, "Khong luu duoc %s: %s\n", ten, ql_mo_ta_loi(m));

    if (m == QL_LOI_GHI)
        fprintf(stderr, "Hay giai phong bot dung luong roi thu lai.\n");

    return 1;
}

printf("Da luu %zu sinh vien vao %s\n", ql.n, ten);