pathbuf(9) [netbsd man page]

PATHBUF(9)						   BSD Kernel Developer's Manual						PATHBUF(9)

NAME

     pathbuf, pathbuf_create, pathbuf_assimilate, pathbuf_copyin, pathbuf_destroy -- path buffer abstraction

SYNOPSIS

     #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);

DESCRIPTION

     The 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().

CODE REFERENCES

     The pathbuf code is part of the name lookup code in sys/kern/vfs_lookup.c.

SEE ALSO

     namei(9)

BUGS

     There are cases where it is necessary to get the path string left behind after 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.

BSD
								 November 30, 2010							       BSD

Check Out this Related Man Page

CONFSTR(3)						     Linux Programmer's Manual							CONFSTR(3)

NAME

       confstr - get configuration dependent string variables

SYNOPSIS

       #include <unistd.h>

       size_t confstr(int name, char *buf, size_t len);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       confstr(): _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE

DESCRIPTION

       confstr() gets the value of configuration-dependent string variables.

       The name argument is the system variable to be queried.	The following variables are supported:

       _CS_GNU_LIBC_VERSION (GNU C library only; since glibc 2.3.2)
	      A string which identifies the GNU C library version on this system (e.g, "glibc 2.3.4").

       _CS_GNU_LIBPTHREAD_VERSION (GNU C library only; since glibc 2.3.2)
	      A string which identifies the POSIX implementation supplied by this C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").

       _CS_PATH
	      A value for the PATH variable which indicates where all the POSIX.2 standard utilities can be found.

       If  buf is not NULL and len is not zero, confstr() copies the value of the string to buf truncated to len - 1 characters if necessary, with
       a null byte ('') as terminator.  This can be detected by comparing the return value of confstr() against len.

       If len is zero and buf is NULL, confstr() just returns the value as defined below.

RETURN VALUE

       If name is a valid configuration variable, confstr() returns the number of bytes (including  the  terminating  null  byte)  that  would	be
       required to hold the entire value of that variable.  This value may be greater than len, which means that the value in buf is truncated.

       If  name is a valid configuration variable, but that variable does not have a value, then confstr() returns 0.  If name does not correspond
       to a valid configuration variable, confstr() returns 0, and errno is set to EINVAL.

ERRORS

       EINVAL If the value of name is invalid.

CONFORMING TO

       POSIX.1-2001.

EXAMPLE

       The following code fragment determines the path where to find the POSIX.2 system utilities:

	   char *pathbuf;
	   size_t n;

	   n = confstr(_CS_PATH,NULL,(size_t) 0);
	   pathbuf = malloc(n);
	   if (pathbuf == NULL)
	       abort();
	   confstr(_CS_PATH, pathbuf, n);

SEE ALSO

       sh(1), exec(3), system(3)

COLOPHON

       This page is part of release 3.27 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2010-02-03								CONFSTR(3)

Linux and UNIX Man Pages

pathbuf(9) [netbsd man page]

Check Out this Related Man Page