JNA ByteBuffer statvfs
我正在尝试使用来自java的statvfs调用来获取/文件夹上的可用空间，
我已经从c检查了statvfs结构的大小，它显示44字节，我已经使用java.nio.ByteBuffer.allocateDirect 44字节分配了一个字节缓冲区，并且它的顺序设置为44字节。 当我调用 statvfs 时，我得到的返回值为 0，所以我假设调用成功，但我似乎无法使用 buffer.getInt 返回 512 f_bsize 从 ByteBuffer 中获取信息，这是正确的，但之后我无法读取。
buffer.getInt(12) 应该给我 f_blocks 但我得到 0。
unsigned long f_bsize; /* File system block size */
unsigned long f_frsize; /* Fundamental file system block size */
fsblkcnt_t f_blocks; /* Blocks on FS in units of f_frsize */
或者我的逻辑有问题吗？
I am trying to get the free space on the / folder using statvfs call from java,
I have check the size of statvfs struct from c it shows 44 bytes, I have allocated a byte buffer using java.nio.ByteBuffer.allocateDirect 44 bytes, and it's order is set to 44 bytes.
when i call statvfs i get a return value of 0, so i am assuming call is successful, but i can't seem to get information out of ByteBuffer using buffer.getInt returns 512 f_bsize which is correct but after that i can't read.
buffer.getInt(12) should give me f_blocks but i get 0.
unsigned long f_bsize; /* File system block size */
unsigned long f_frsize; /* Fundamental file system block size */
fsblkcnt_t f_blocks; /* Blocks on FS in units of f_frsize */
or do i have a fault in my logic?
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不是解决方案，而是一些想法。
fsblkcnt_t类型的大小。我非常肯定它是 4 个字节，但这只是基于整个结构的 44 个字节的假设。f_blocks字段的第一个字节的索引是8，而不是12。f_bsize和f_frsize各为4个字节，总共是 8 个字节，下一个值从第九个位置（索引 8）开始。Byteorder.BIG_ENDIAN或ByteOrder.LITTLE_ENDIAN。但也许这只是您问题中的一个拼写错误您是否尝试过转储缓冲区内容或使用调试器来查看缓冲区？它是否符合预期值？只是为了弄清楚问题是否与填充或读取缓冲区有关。
Not a solution but a few thoughts.
fsblkcnt_ttype. I'm quite positive, that it is 4 bytes, but that's just an assumption based on your 44 bytes for the whole struct.f_blocksfield is 8, not 12.f_bsizeandf_frsizeare 4 bytes each, the total is 8 bytes, the next value starts at the nineth position which is index 8.Byteorder.BIG_ENDIANorByteOrder.LITTLE_ENDIAN. But maybe that's just a typo in your questionHave your tried dumping the buffer content or used a debugger to peek into the buffer? Does it hold the expected values? Just to sort out, if the problem is related to filling or to reading the buffer.