illumos: manual page: u8

U8_VALIDATE(3C) Standard C Library Functions U8_VALIDATE(3C)

NAME

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

SYNOPSIS

#include <sys/u8_textprep.h>

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

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 errnum 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.

errnum
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 errnum to
indicate the error.

EXAMPLES

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

#include <sys/u8_textprep.h>

char u8[MAXPATHLEN];
int errnum;
.
.
.
len = u8_validate(u8, 4, (char **)NULL, 0, &errnum);
if (len == -1) {
switch (errnum) {
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/u8_textprep.h>

char u8[MAXPATHLEN];
int n;
int errnum;
.
.
.
n = strlen(u8);
len = u8_validate(u8, n, (char **)NULL, U8_VALIDATE_ENTIRE, &errnum);
if (len == -1) {
switch (errnum) {
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/u8_textprep.h>

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

ATTRIBUTES