Tribblix: manual page: u8

U8_VALIDATE(9F) Kernel Functions for Drivers U8_VALIDATE(9F)

NAME

u8_validate - validate UTF-8 characters and calculate the byte length

SYNOPSIS

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

int u8_validate(char *u8str, size_t n, char **list, int flag,
int *errno);

INTERFACE LEVEL

illumos DDI specific (illumos DDI)

PARAMETERS

u8str
The UTF-8 string to be validated.

n
The maximum number of bytes in u8str that can be examined
and validated.

list
A list of null-terminated character strings in UTF-8 that
must be additionally checked against as invalid characters.
The last string in list must be null to indicate there is no
further string.

flag
Possible validation options constructed by a bitwise-
inclusive-OR of the following values:

U8_VALIDATE_ENTIRE

By default, u8_validate() looks at the first character
or up to n bytes, whichever is smaller in terms of the
number of bytes to be consumed, and returns with the
result.

When this option is used, u8_validate() will check up to
n bytes from u8str and possibly more than a character
before returning the result.

U8_VALIDATE_CHECK_ADDITIONAL

By default, u8_validate() does not use list supplied.

When this option is supplied with a list of character
strings, u8_validate() additionally validates u8str
against the character strings supplied with list and
returns EBADF in errno if u8str has any one of the
character strings in list.

U8_VALIDATE_UCS2_RANGE

By default, u8_validate() uses the entire Unicode coding
space of U+0000 to U+10FFFF.

When this option is specified, the valid Unicode coding
space is smaller to U+0000 to U+FFFF.

errno
An error occurred during validation. The following values
are supported:

EBADF
Validation failed because list-specified
characters were found in the string pointed to by
u8str.

EILSEQ
Validation failed because an illegal byte was
found in the string pointed to by u8str.

EINVAL
Validation failed because an incomplete byte was
found in the string pointed to by u8str.

ERANGE
Validation failed because character bytes were
encountered that are outside the range of the
Unicode coding space.

DESCRIPTION

The u8_validate() function validates u8str in UTF-8 and determines
the number of bytes constituting the character(s) pointed to by
u8str.

RETURN VALUES

If u8str is a null pointer, u8_validate() returns 0. Otherwise,
u8_validate() returns either the number of bytes that constitute the
characters if the next n or fewer bytes form valid characters, or -1
if there is an validation failure, in which case it may set errno to
indicate the error.

EXAMPLES

Example 1: Determine the length of the first UTF-8 character.

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

char u8[MAXPATHLEN];
int errno;
.
.
.
len = u8_validate(u8, 4, (char **)NULL, 0, &errno);
if (len == -1) {
switch (errno) {
case EILSEQ:
case EINVAL:
return (MYFS4_ERR_INVAL);
case EBADF:
return (MYFS4_ERR_BADNAME);
case ERANGE:
return (MYFS4_ERR_BADCHAR);
default:
return (-10);
}
}

Example 2: Check if there are any invalid characters in the entire

string.

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

char u8[MAXPATHLEN];
int n;
int errno;
.
.
.
n = strlen(u8);
len = u8_validate(u8, n, (char **)NULL, U8_VALIDATE_ENTIRE, &errno);
if (len == -1) {
switch (errno) {
case EILSEQ:
case EINVAL:
return (MYFS4_ERR_INVAL);
case EBADF:
return (MYFS4_ERR_BADNAME);
case ERANGE:
return (MYFS4_ERR_BADCHAR);
default:
return (-10);
}
}

Example 3: Check if there is any invalid character, including

prohibited characters, in the entire string.

#include <sys/types.h>
#include <sys/errno.h>
#include <sys/sunddi.h>

char u8[MAXPATHLEN];
int n;
int errno;
char *prohibited[4] = {
".", "..", "\\", NULL
};
.
.
.
n = strlen(u8);
len = u8_validate(u8, n, prohibited,
(U8_VALIDATE_ENTIRE|U8_VALIDATE_CHECK_ADDITIONAL), &errno);
if (len == -1) {
switch (errno) {
case EILSEQ:
case EINVAL:
return (MYFS4_ERR_INVAL);
case EBADF:
return (MYFS4_ERR_BADNAME);
case ERANGE:
return (MYFS4_ERR_BADCHAR);
default:
return (-10);
}
}

ATTRIBUTES