fusion 文件系统无法更改 getattr 函数中 struct stat *stbuf 的值？

Question

问题解决了！ 感谢@basile-starynkevitch，我发现不同文件中的 struct stat 大小不一样！

在中，sizeof(struct stat)是88字节，但是带有fuse的lib(我猜是由于-D_FILE_OFFSET_BITS=64< /code> 标志），这是 96 字节。

因此，当我将 fusion lib 添加到远程服务器时（将 -D_FILE_OFFSET_BITS=64 /usr/local/lib/libfuse.so /usr/local/lib/libulockmgr.so 标志添加到 gcc 中），那么我的程序运行正确！

感谢您的帮助！

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我正在 fusion 上做一些项目，这让我抓狂。

我从远程服务器发送 struct stat *stbuf 的数据，并且数据在服务器和客户端中都是正确的，但是当我使用 memcpy 将数据复制到 stbuf 时，似乎没有复制任何内容。我还尝试使用 read(socked,stbuf,sizeof(struct stat));直接，但这也不起作用。

这是代码...（如果没有这样的文件，远程服务器将 -ENOENT 保存在 st_ino 中）

    static int rof_getattr(const char *path, struct stat *stbuf)

        {

    int res = 0;
    struct cmd sndcmd;
    struct stat buf;

    memset(&sndcmd, 0, sizeof(struct cmd));

    strcpy(sndcmd.cmd, "GETATTR");
    strcpy(sndcmd.str, path);
    memset(stbuf, 0, sizeof(struct stat));
GTTR_AGN:   
    memset(&buf, 0,sizeof(struct stat));
    write(sockfd, &sndcmd, sizeof(struct cmd));
    res=read(sockfd, &buf, sizeof(struct stat));

    if(res!=sizeof(struct stat))
        goto GTTR_AGN;

    memcpy(stbuf,&buf,sizeof(buf));
    if (buf.st_ino==-ENOENT)
        return -ENOENT;
return 0;
        }

我从 gdb 获取的数据：

39      res=read(sockfd, &buf, sizeof(struct stat));
3: (struct stat)stbuf = {st_dev = 694294557525955008, __pad1 = 0, __st_ino = 0, 
  st_mode = 0, st_nlink = 0, st_uid = 0, st_gid = 0, st_rdev = 0, __pad2 = 0, 
  st_size = 0, st_blksize = 0, st_blocks = 0, st_atim = {tv_sec = 0, tv_nsec = 0}, 
  st_mtim = {tv_sec = 0, tv_nsec = 0}, st_ctim = {tv_sec = 0, tv_nsec = 0}, 
  st_ino = 0}
1: buf = {st_dev = 0, __pad1 = 0, __st_ino = 0, st_mode = 0, st_nlink = 0, 
  st_uid = 0, st_gid = 0, st_rdev = 0, __pad2 = 0, st_size = 0, st_blksize = 0, 
  st_blocks = 0, st_atim = {tv_sec = 0, tv_nsec = 0}, st_mtim = {tv_sec = 0, 
    tv_nsec = 0}, st_ctim = {tv_sec = 0, tv_nsec = 0}, st_ino = 0}

在 read() 之后，在 buf 中获取数据

(gdb) s
40      memcpy(stbuf,&buf,sizeof(buf));
3: (struct stat)stbuf = {st_dev = 694294557525955008, __pad1 = 2049, __st_ino = 0, 
  st_mode = 0, st_nlink = 943887, st_uid = 16877, st_gid = 2, 
  st_rdev = 4294967297000, __pad2 = 0, st_size = 0, st_blksize = 4096, 
  st_blocks = 34359742464, st_atim = {tv_sec = 1323833759, tv_nsec = 75415995}, 
  st_mtim = {tv_sec = 1323729515, tv_nsec = 6514929}, st_ctim = {
    tv_sec = 1323729515, tv_nsec = 6514929}, st_ino = 0}
1: buf = {st_dev = 2049, __pad1 = 0, __st_ino = 943887, st_mode = 16877, 
  st_nlink = 2, st_uid = 1000, st_gid = 1000, st_rdev = 0, __pad2 = 0, 
  st_size = 17592186048512, st_blksize = 8, st_blocks = 323909233444133279, 
  st_atim = {tv_sec = 1323729515, tv_nsec = 6514929}, st_mtim = {
    tv_sec = 1323729515, tv_nsec = 6514929}, st_ctim = {tv_sec = 0, tv_nsec = 0}, 
  st_ino = 0}
(gdb) s

将数据复制到 stbuf

41      if (stbuf->st_ino==-ENOENT)
3: (struct stat)stbuf = {st_dev = 694294557525955008, __pad1 = 2049, __st_ino = 0, 
  st_mode = 0, st_nlink = 943887, st_uid = 16877, st_gid = 2, 
  st_rdev = 4294967297000, __pad2 = 0, st_size = 0, st_blksize = 4096, 
  st_blocks = 34359742464, st_atim = {tv_sec = 1323833759, tv_nsec = 75415995}, 
  st_mtim = {tv_sec = 1323729515, tv_nsec = 6514929}, st_ctim = {
    tv_sec = 1323729515, tv_nsec = 6514929}, st_ino = 0}
1: buf = {st_dev = 2049, __pad1 = 0, __st_ino = 943887, st_mode = 16877, 
  st_nlink = 2, st_uid = 1000, st_gid = 1000, st_rdev = 0, __pad2 = 0, 
  st_size = 17592186048512, st_blksize = 8, st_blocks = 323909233444133279, 
  st_atim = {tv_sec = 1323729515, tv_nsec = 6514929}, st_mtim = {
    tv_sec = 1323729515, tv_nsec = 6514929}, st_ctim = {tv_sec = 0, tv_nsec = 0}, 
  st_ino = 0}

stbuf 根本没有改变。

有人可以给我一些关于这种现象的建议吗？我已经做了一些工作，但仍然没有找到解决方案。

Answer 1

您不会在代码中检查读取的字节数 res。

在文件末尾它可以是 0，在错误时它可以是 -1，如果没有接收到所有字节，它可能小于 sizeof(struct stat)...

阅读（用你的眼睛）和大脑）非常仔细地（并再次阅读两次）read(2) 的手册页 系统调用。