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$FreeBSD$

.Dd November 23, 2008 .Dt VN_FULLPATH 9 .Os .Sh NAME .Nm vn_fullpath .Nd "convert a vnode reference to a full pathname, given a process context" .Sh SYNOPSIS n sys/param.h n sys/vnode.h .Ft int .Fo vn_fullpath .Fa "struct thread *td" "struct vnode *vp" "char **retbuf" "char **freebuf" .Fc .Sh DESCRIPTION The .Fn vn_fullpath function makes a .Dq "best effort" attempt to generate a string pathname for the passed vnode; the resulting path, if any, will be relative to the root directory of the process associated with the passed thread pointer. The .Fn vn_fullpath function is implemented by inspecting the VFS name cache, and attempting to reconstruct a path from the process root to the object.

p This process is necessarily unreliable for several reasons: intermediate entries in the path may not be found in the cache; files may have more than one name (hard links), not all file systems use the name cache (specifically, most synthetic file systems do not); a single name may be used for more than one file (in the context of file systems covering other file systems); a file may have no name (if deleted but still open or referenced). However, the resulting string may still be more useable to a user than a vnode pointer value, or a device number and inode number. Code consuming the results of this function should anticipate (and properly handle) failure.

p Its arguments are: l -tag -width ".Fa freebuf" t Fa td The thread performing the call; this pointer will be dereferenced to find the process and its file descriptor structure, in order to identify the root vnode to use. t Fa vp The vnode to search for. No need to be locked by the caller. t Fa retbuf Pointer to a .Vt "char *" that .Fn vn_fullpath may (on success) point at a newly allocated buffer containing the resulting pathname. t Fa freebuf Pointer to a .Vt "char *" that .Fn vn_fullpath may (on success) point at a buffer to be freed, when the caller is done with .Fa retbuf . .El

p Typical consumers will declare two character pointers: .Va fullpath and .Va freepath ; they will set .Va freepath to .Dv NULL , and .Va fullpath to a name to use in the event that the call to .Fn vn_fullpath fails. After done with the value of .Va fullpath , the caller will check if .Va freepath is

f non- Dv NULL , and if so, invoke .Xr free 9 with a pool type of .Dv M_TEMP . .Sh RETURN VALUES If the vnode is successfully converted to a pathname, 0 is returned; otherwise, an error number is returned. .Sh SEE ALSO .Xr free 9 .Sh AUTHORS This manual page was written by .An Robert Watson Aq rwatson@FreeBSD.org .