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

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

See Also

u8_strcmp(3C), u8_textprep_str(3C), attributes(5), u8_strcmp(9F), u8_textprep_str(9F), u8_validate(9F)

The Unicode Standard