VOP_ATTRIB(9)

💖 VOP_ATTRIB — it's giving "get and set attributes" energy ✨

okay bestie so this is from the Kernel Developer's Manual, section 9, and the page is called VOP_ATTRIB(9) 🎀 buckle up because we're talking about VOP_GETATTR and VOP_SETATTR, the duo that gets and sets attributes on a file or directory. no cap. 🦋

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✨ NAME ✨

VOP_GETATTR, VOP_SETATTR — get and set attributes on a file or directory 💅

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🌸 SYNOPSIS 🌸

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

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

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

like. look at those signatures. iconic. 🫶

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💅 DESCRIPTION 💅

These entry points manipulate various attributes of a file or directory, and the list is lowkey long: file permissions, owner, group, size, access time and modification time. all of it. the whole glow-up kit. ✨

The arguments are:

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

okay this part matters so listen up fr fr 👑

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.

so yes: VNOVAL for the stuff you're not touching, VATTR_NULL() to wipe *vap clean before you set the specific values you actually care about. reset first, then slay. 🧼➡️💅

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🔒 LOCKS 🔒

VOP_GETATTR() expects the vnode to be locked on entry and will leave the vnode locked on return. The lock type can be either shared or exclusive. so flexible. we love options. 💖

VOP_SETATTR() expects the vnode to be locked on entry and will leave the vnode locked on return. The lock type must be exclusive. no shared vibes allowed here bestie, it's exclusive-only main character energy. 👑

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🌈 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. periodt. 💅

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💀 ERRORS 💀

• [EPERM] — The file is immutable. like it said no and meant it. 🚫
• [EACCES] — The caller does not have permission to modify the file or directory attributes. bestie you do not have the range. 😭
• [EROFS] — The file system is read-only. nothing to see here, it's frozen. 🧊

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👀 SEE ALSO 👀

VFS(9), vnode(9), VOP_ACCESS(9) — go read those next, iykyk 📚✨

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🫶 AUTHORS 🫶

This manual page was written by Doug Rabson. ty king for your service 🙏👑

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and that's the whole page bestie!! 🎀 this version lives over on Debian, dated August 29, 2008, so like… vintage but still eating. 💖✨🦋