#On ZFS, how can I read a file as an inode or znode struct?

29 messages · Page 1 of 1 (latest)

scarlet cove
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I'm trying to write a programme on FreeBSD to interact with the filesystem (ZFS, in this case), so I am trying to read a file as either a znode or inode struct. There are very few online resources for this—is this possible to do (without casting)?

upper rampartBOT
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rocky onyx
scarlet cove
rocky onyx
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the stat struct contains the information of the given inode
type, owner, group, ...

scarlet cove
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@rocky onyx I might be mistaken but I think an inode struct in ZFS/BSD is not the same as the inode field in the stat struct

rocky onyx
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the inode field in thr stat struct is just the number of where its located in the inode table

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the rest of the members are the information related to this inode

scarlet cove
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There's an inode table? 😅

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Sorry I don't know much about C...

rocky onyx
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(and unix as it seems)

scarlet cove
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Yeah, I haven'e done much low-level programming

rocky onyx
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dont get me wrong i dont know alot either

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just trying to help

scarlet cove
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Thanks, I appreciate it. So do you know how I can access this inode table>

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?*

rocky onyx
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you might want to get a copy of "the linux programming interface"

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and read chapter 14

scarlet cove
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Okay, thanks 🙂

rocky onyx
scarlet cove
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Okay, well thank you, I'll see if I can figure it out 🙂

rocky onyx
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i dont really know what you want to do, but i think stat() should suffice

except you plan on hacking on the filesystem itself

scarlet cove
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Lol, not trying to hack the filesystem. Actually, the ultimate goal is to get the z_pflags (https://github.com/openzfs/zfs/blob/ede037cda73675f42b1452187e8dd3438fafc220/include/sys/zfs_znode.h#L200) field from the znode struct. However, as I have had limited success with anything related to znode, and I found an ITOZ conversion function (https://github.com/openzfs/zfs/blob/ede037cda73675f42b1452187e8dd3438fafc220/include/os/freebsd/zfs/sys/zfs_znode_impl.h#L104), so I thought I could try getting the znode from an inode

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Actually, it looks like I might need to figure out vnode in this case, not inode...I'm so confused haha

rocky onyx
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you might want to find a commandline util that does this

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eg debugfs

scarlet cove
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There is zfs list, but I'll take a look at debugfs