VND_ERRNO(3VND) VND_ERRNO(3VND)


NAME


vnd_errno, vnd_syserrno, vnd_strerror, vnd_strsyserror - obtain and
translate vnd errors


SYNOPSIS


cc [ flag... ] file... -lvnd [ library... ]
#include <libvnd.h>

uint32_t vnd_errno(vnd_handle_t *vhp);

const char *vnd_strerror(vnd_errno_t err);

int vnd_syserrno(vnd_handle_t *vhp);

const char *vnd_strsyserror(int syserr);


DESCRIPTION


The libvnd(3LIB) library supports a complementary array of errors that
give more specific error information than the traditional set of system
errors available via errno(3C). When an error occurs, consumers should
call the vnd_errno function first and check its value. If the value of
the vnd_errno_t is VND_E_SYS, then the system errno should be checked. If
the vnd_errno_t is not VND_E_SYS, then the contents of the system errno
returned from vnd_syserrno are undefined. Both the vnd and system errors
are only valid for a given handle after a libvnd library function
returned an error and before another libvnd library function is called on
the same handle. The act of making an additional function call with the
same vnd_handle_t invalidates any prior vnd or system error numbers. For
the full list of valid vnd errors see libvnd(3LIB). For the full list of
valid system errors, see Intro(2).


The vnd_errno and vnd_syserrno functions retrieve the most recent vnd and
syserr error number respectively from a vnd handle vhp.


The vnd_strerror function translates a vnd_errno_t err to a corresponding
string and returns a pointer to that constant string.


The vnd_syserrno function is analogous to the vnd_strerror function,
except that it translates a system error back to a string.


RETURN VALUES


The vnd_errno function returns a vnd_errno_t which contains the vnd error
information.


The vnd_syserror function returns an integer which contains the system
error information. These values are the same as those returned by
errno(3C).


The vnd_strerror function returns a pointer to a constant string. If the
error passed in is unknown, the string "unknown error" is returned.


The vnd_strsyserror function returns a pointer to the translated constant
string. If an unknown error number is passed, it returns the string
"Unknown error". If an error occurs, it returns a NULL pointer.


EXAMPLES


Example 1 Obtaining errors from a vnd_handle_t


The following sample C function, which can be incorporated into a larger
program, shows how to obtain the vnd and system errors from a
vnd_handle_t after a vnd interface on a handle failed.


#include <libvnd.h>

static void
print_errnos(vnd_handle_t *vhp)
{
vnd_errno_t vnderr;
int syserr;

vnderr = vnd_errno(vhp);
syserr = vnd_syserrno(vhp);

(void) printf("vnd err: %d, sys err: %d0,
vnderr, syserr);
}


Example 2 A perror-like function


The following sample C function which can be incorporated into a larger
program shows how to write a perror-like function to print out error
messages for a vnd device.


#include <libvnd.h>

static void
sample_perror(const char *msg, vnd_error_t vnderr, int syserr)
{
(void) fprintf(stderr, "%s: %s", msg,
vnderr != VND_E_SYS ? vnd_strerror(vnderr) :
vnd_strsyserror(syserr));
}


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|Stability | Committed |
+---------------+-----------------+
|MT-Level | See below |
+---------------+-----------------+

The MT-Level of the functions vnd_strerror and vnd_strsyserror is MT-
Safe. See "THREADING" in libvnd(3LIB) for a discussion of the MT-Level of
vnd_errno and vnd_syserrno.


SEE ALSO


Intro(2), errno(3C), libvnd(3LIB), attributes(5)


February 21, 2014 VND_ERRNO(3VND)