Проект OpenNet: MAN VOP_MKNOD (9) Ядро (FreeBSD и Linux)

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VOP_MKNOD (9)

>> VOP_MKNOD (9) ( FreeBSD man: Ядро )

BSD mandoc

NAME

VOP_CREATE

 
VOP_MKNOD

 
VOP_MKDIR

 
VOP_SYMLINK

 - create a file, socket, fifo, device, directory or symlink

SYNOPSIS

   #include <sys/param.h>
   #include <sys/vnode.h>
   #include <sys/namei.h>
int VOP_CREATE (struct vnode *dvp struct vnode **vpp struct componentname *cnp struct vattr *vap);
int VOP_MKNOD (struct vnode *dvp struct vnode **vpp struct componentname *cnp struct vattr *vap);
int VOP_MKDIR (struct vnode *dvp struct vnode **vpp struct componentname *cnp struct vattr *vap);
int VOP_SYMLINK (struct vnode *dvp struct vnode **vpp struct componentname *cnp struct vattr *vap char *target);

DESCRIPTION

These entry points create a new file, socket, fifo, device, directory or symlink in a given directory.

The arguments are:

Fa dvp: The locked vnode of the directory.
Fa vpp: The address of a variable where the resulting locked vnode should be stored.
Fa cnp: The pathname component created.
Fa vap: The attributes that the new object should be created with.
Fa target: The pathname of the target of the symlink.

These entry points are called after VOP_LOOKUP9 when an object is being created.

LOCKS

The directory, Fa dvp will be locked on entry and must remain locked on return. If the call is successful, the new object will be returned locked.

RETURN VALUES

If successful, the vnode for the new object is placed in Fa *vpp and zero is returned. Otherwise, an appropriate error is returned.

PSEUDOCODE

int
vop_create(struct vnode *dvp,
           struct vnode **vpp,
           struct componentname *cnp
           struct vattr *vap)
{
    int mode = MAKEIMODE(vap->va_type, vap->va_mode);
    struct vnode *vp;
    int error;

    *vpp = NULL;
    if ((mode & IFMT) == 0)
        mode |= IFREG;

    error = SOMEFS_VALLOC(dvp, mode, cnp->cn_cred, &vp);
    if (error)
        return error;

    /*
     * Update the permissions for the new vnode, including
     * copying the group from the directory.
     */
    ...;

#ifdef QUOTA
    /*
     * Possibly check quota information.
     */
    ...;
#endif

    /*
     * Enter new vnode in directory, taking care that the vnode
     * hits the disk before the directory contents are changed.
     */
    error = ...;

    if (error)
        goto bad;

    *vpp = vp;

    return 0;

bad:
    /*
     * Write error occurred trying to update the inode
     * or the directory so must deallocate the inode.
     */
    vput(vp);

    /*
     * Deallocate file system resources for vp.
     */
    ...;

    return error;
}