PATHBUF(9) | Kernel Developer's Manual | PATHBUF(9) |
pathbuf
, pathbuf_create
,
pathbuf_assimilate
,
pathbuf_copyin
,
pathbuf_destroy
—
#include <sys/namei.h>
struct pathbuf *
pathbuf_create
(const
char *path);
struct pathbuf *
pathbuf_assimilate
(char
*pnbuf);
int
pathbuf_copyin
(const
char *userpath, struct
pathbuf **ret);
void
pathbuf_destroy
(struct
pathbuf *path);
pathbuf
interface is used to carry around pathnames.
This helps simplify the namei(9)
interface. A pathbuf should be thought of as a path name string combined with
whatever flags and metadata are needed to interpret it correctly. It is an
abstract type; the internals are hidden within the
namei(9) implementation.
The pathbuf_create
() function allocates
and initializes a new pathbuf containing a copy of the path string
path, which should be a kernel pointer. The return
value should be checked for being NULL
in case the
system is out of memory. Passing a path name larger than
PATH_MAX
will cause an assertion failure.
The pathbuf_copyin
() function allocates
and initializes a new pathbuf containing a path string copied from user
space with copyinstr(9). It
returns an error code.
The pathbuf_assimilate
() function creates
a pathbuf using the string buffer provided as pnbuf.
This buffer must be of size PATH_MAX
and must have
been allocated with PNBUF_GET
(). The buffer is
“taken over” by the returned pathbuf and will be released when
the pathbuf is destroyed. Note: to avoid confusion and pointer bugs,
pathbuf_assimilate
() should only be used where
absolutely necessary; e.g. the NFS server code uses it to generate pathbufs
from strings fetched from mbufs.
The pathbuf_destroy
() function deallocates
a pathbuf. Caution: because calling
namei(9) loads pointers to
memory belonging to the pathbuf into the nameidata structure, a pathbuf
should only be destroyed by the namei
() caller once
all manipulations of the nameidata are complete.
Also note that calling namei
() destroys
the contents of the pathbuf. Do not reuse a pathbuf for a second call to
namei
().
pathbuf
code is part of the name lookup code in
sys/kern/vfs_lookup.c.
namei
() has run. This produces an effect similar to
realpath(3). The interface for
doing this is, for the time being, intentionally undocumented and subject to
change.
November 30, 2010 | NetBSD 9.2 |