table of contents
VOP_LOOKUP(9) | Kernel Developer's Manual | VOP_LOOKUP(9) |
NAME¶
VOP_LOOKUP — lookup a component of a pathnameSYNOPSIS¶
#include <sys/param.h>#include <sys/vnode.h>
#include <sys/namei.h> int
VOP_LOOKUP(struct vnode *dvp, struct vnode **vpp, struct componentname *cnp);
DESCRIPTION¶
This entry point looks up a single pathname component in a given directory. Its arguments are:- dvp
- The locked vnode of the directory to search.
- vpp
- The address of a variable where the resulting locked vnode should be stored.
- cnp
- The pathname component to be searched for.
struct componentname { /* * Arguments to lookup. */ u_long cn_nameiop; /* namei operation */ u_long cn_flags; /* flags to namei */ struct thread *cn_thread; /* thread requesting lookup */ struct ucred *cn_cred; /* credentials */ /* * Shared between lookup and commit routines. */ char *cn_pnbuf; /* pathname buffer */ char *cn_nameptr; /* pointer to looked up name */ long cn_namelen; /* length of looked up component */ u_long cn_hash; /* hash value of looked up name */ long cn_consume; /* chars to consume in lookup() */ };
LOOKUP
, CREATE
,
RENAME
, or DELETE
depending on
the intended use of the object. When CREATE
,
RENAME
, or DELETE
is
specified, information usable in creating, renaming, or deleting a directory
entry may be calculated.
Overall outline of VOP_LOOKUP:
Check accessibility of directory.
Look for name in cache, if found, then return name. Search for name in
directory, goto to found or notfound as appropriate.
notfound:
If creating or renaming and at end
of pathname, return
found:
EJUSTRETURN
, leaving info on
available slots else return ENOENT
.If at end of path and deleting,
return information to allow delete. If at end of path and renaming, lock
target inode and return info to allow rename. If not at end, add name to
cache; if at end and neither creating nor deleting, add name to cache.
LOCKS¶
The directory, dvp should be locked on entry. If an error (note: the return valueEJUSTRETURN
is not considered
an error) is detected, it will be returned locked. Otherwise, it will be
unlocked unless both LOCKPARENT
and
ISLASTCN
are specified in
cnp->cn_flags. If an entry is found in the directory,
it will be returned locked.
RETURN VALUES¶
Zero is returned with *vpp set to the locked vnode of the file if the component is found. If the component being searched for is ".", then the vnode just has an extra reference added to it with vref(9). The caller must take care to release the locks appropriately in this case. If the component is not found and the operation isCREATE
or RENAME
, the flag
ISLASTCN
is specified and the operation would succeed,
the special return value EJUSTRETURN
is returned.
Otherwise, an appropriate error code is returned.
ERRORS¶
- [
ENOTDIR
] - The vnode dvp does not represent a directory.
- [
ENOENT
] - The component dvp was not found in this directory.
- [
EACCES
] - Access for the specified operation is denied.
- [
EJUSTRETURN
] - A
CREATE
orRENAME
operation would be successful.
SEE ALSO¶
vnode(9), VOP_ACCESS(9), VOP_CREATE(9), VOP_MKDIR(9), VOP_MKNOD(9), VOP_RENAME(9), VOP_SYMLINK(9)HISTORY¶
The function VOP_LOOKUP appeared in 4.3BSD.AUTHORS¶
This manual page was written by Doug Rabson, with some text from comments in ufs_lookup.c.November 24, 1997 | Debian |