VOP_ATTRIB(9)

🌸 NAME — VOP_ATTRIB(9) 🌸

okay so bestie, this is VOP_ATTRIB(9) from the Kernel Developer's Manual: the page for VOP_GETATTR, VOP_SETATTR — get and set attributes on a file or directory. ✨

✨ SYNOPSIS ✨

the way this synopsis is giving exact-prototype energy:

       #include <sys/param.h>
       #include <sys/vnode.h>

       int
       VOP_GETATTR(struct, vnode, *vp, flags, struct, vattr, *vap, struct,
           ucred, *cred);

       int
       VOP_SETATTR(struct, vnode, *vp, struct, vattr, *vap, struct, ucred,
           *cred);

       int
       VOP_STAT(struct, vnode, *vp, struct, stat, *sb, flags, struct, ucred,
           *active_cred, struct, ucred, *file_cred);

💅 DESCRIPTION 💅

okay so these entry points manipulate various attributes of a file or directory, including file permissions, owner, group, size, access time and modification time. periodt.

VOP_STAT() returns data in a format suitable for the stat(2) system call and by default is implemented as a wrapper around VOP_GETATTR(). Filesystems may want to implement their own variant for performance reasons. 🦋

For VOP_GETATTR() and VOP_SETATTR() the arguments are:

• vp — The vnode of the file.
• vap — The attributes of the file.
• cred — The user credentials of the calling thread.

For VOP_STAT() the arguments are:

• vp — The vnode of the file.
• sb — The attributes of the file.
• active_cred — The user credentials of the calling thread.
• file_cred — The credentials installed on the file description pointing to the vnode or NOCRED.

Attributes which are not being modified by VOP_SETATTR() should be set to the value VNOVAL; VATTR_NULL() may be used to clear all the values, and should generally be used to reset the contents of *vap prior to setting specific values. iykyk.

🔒 LOCKS 🔒

lock vibe check, no cap:

• Both VOP_GETATTR() and VOP_STAT() expect the vnode to be locked on entry and will leave the vnode locked on return. The lock type can be either shared or exclusive.
• VOP_SETATTR() expects the vnode to be locked on entry and will leave the vnode locked on return. The lock type must be exclusive.

🎀 RETURN VALUES 🎀

• VOP_GETATTR() returns 0 if it was able to retrieve the attribute data via *vap, otherwise an appropriate error is returned.
• VOP_SETATTR() returns zero if the attributes were changed successfully, otherwise an appropriate error is returned.
• VOP_STAT() returns 0 if it was able to retrieve the attribute data *sb, otherwise an appropriate error is returned.

💀 ERRORS 💀

• [EPERM] — The file is immutable.
• [EACCES] — The caller does not have permission to modify the file or directory attributes.
• [EROFS] — The file system is read-only.

👀 SEE ALSO 👀

• VFS(9)
• vnode(9)
• VOP_ACCESS(9)

🫶 AUTHORS 🫶

This manual page was written by Doug Rabson. 👑

💌 footer vibe: source/version + date, bestie — Debian, October 2, 2021. bye! 🫶