VOP_ACCESS(9)

🌸 NAME 🌸

okay so welcome to the VOP_ACCESS(9) manual page from the Kernel Developer’s Manual, bestie 💖 — this one covers VOP_ACCESS, VOP_ACCESSX, and their whole thing: checking access permissions of a file or a Unix domain socket. periodt.

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✨ SYNOPSIS ✨

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

int
VOP_ACCESS(struct vnode *vp, accmode_t accmode, struct ucred *cred,
    struct thread *td);

int
VOP_ACCESSX(struct vnode *vp, accmode_t accmode, struct ucred *cred,
    struct thread *td);

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🦋 DESCRIPTION 🦋

This entry point is literally the permission-check main character: it checks the access permissions of the file against the given credentials. no cap.

Its arguments are giving:

• vp — the vnode of the file to check. the file’s little kernel-side representative 💅
• accmode — the type of access required.
• cred — the user credentials to check.
• td — the thread which is checking.

The accmode is a mask which can contain flags described in <sys/vnode.h>, e.g. VREAD, VWRITE or VEXEC. For VOP_ACCESS(), the only flags that may be set in accmode are VEXEC, VWRITE, VREAD, VADMIN and VAPPEND. To check for other flags, one has to use VOP_ACCESSX() instead. iykyk 🔥

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🔒 LOCKS 🔒

The vnode will be locked on entry and should remain locked on return. so like… it comes in locked and leaves locked, bestie — don’t be weird about it 🫶

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🎀 RETURN VALUES 🎀

If the file is accessible in the specified way, then zero is returned, otherwise an appropriate error code is returned. slay when it’s zero, sad little error code when it’s not 😭

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💀 ERRORS 💀

• [EPERM] — An attempt was made to change an immutable file.
• [EACCES] — The permission bits the file mode or the ACL do not permit the requested access.

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👑 SEE ALSO 👑

• vaccess(9)
• vaccess_acl_nfs4(9)
• vaccess_acl_posix1e(9)
• vnode(9)

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🫶 AUTHORS 🫶

This manual page was written by Doug Rabson. iconic behavior, honestly 🌈

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This page came from Debian, dated September 18, 2009, and its manual-page tag is VOP_ACCESS(9) 💖✨