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递归遍历目录时C中的gmtime不一致

time-t directory time recursion c

Kagemand Andersen · 技术社区 · 6 年前

我有一个C程序,我使用递归函数遍历目录结构。它需要一个 time_t

递归dir函数来自 How to recursively list directories in C on Linux?

void traversedir(time_t cutoff, const char* name, int indent)
{
    if (indent > 9)
        return;

    DIR* dir;
    struct dirent* entry;

    if (!(dir = opendir(name)))
        return;

    struct tm *t = gmtime(&cutoff);
    printf("%d-%d-%d %d:%d:%d (%lld)\n", (1900 + t->tm_year), (t->tm_mon + 1), t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, (long long) cutoff);
    sleep(1);  // only for debugging

    while ((entry = readdir(dir)) != NULL) {
        if (entry->d_type == DT_DIR) {
            char path[1024];
            if (entry->d_name[0] == '.' && !isValidNumber(entry->d_name))
                continue;
            snprintf(path, sizeof(path), "%s/%s", name, entry->d_name);

            ...

            traversedir(cutoff, path, indent + 2);
        }
    }
    closedir(dir);
}

void imageCleanup()
{
    time_t cutoff = (time(NULL) - (86400 * 10));
    do {
        printf("Cutoff: %lld\n", (long long) cutoff);
        traversedir(cutoff, "/path/to/dir", 0);
        sleep(2);
        cutoff += 3600;
    } while (!available_storage() && cutoff < time(NULL));
}

Cutoff: 1534245930
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:31 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:33 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:35 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:38 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:43 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:52 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:54 (1534245930)
2018-8-14 11:25:55 (1534245930)
2018-8-24 11:25:56 (1534245930)
2018-8-14 11:25:30 (1534245930)
2018-8-24 11:25:58 (1534245930)

时间 从中转换结构的位置在括号中。它是始终如一的 1534245930 或2018年8月14日上午11:25:30,即程序执行时的负十天。

你可以看到转换非常不一致。执行时,秒数会跟随实际时间几次。日子也变了几次。

有人知道或知道是什么导致的吗?我试着做一个简单的循环来转换一个静态的 时间

1 回复 | 直到 6 年前

Basile Starynkevitch 6 年前

仔细阅读 time(7) 和 gmtime(3) .

请注意 gmtime 不是 reentrant 因为它返回一些静态数据的地址。你想要的 gmtime_r (自从你 traversedir struct tm automatic variable .

struct tm mytm;
struct tm *t = gmtime_r(&cutoff, &mytm);

那么 t 会指向 mytm call stack

strftime(3) (同样,有足够大的缓冲区声明为自动变量,或一些堆分配的缓冲区)。

nftw(3) 和 stat(2) .

How to debug small programs .