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lib/ucs2_string: Add UCS-2 strscpy function 

Add a ucs2_strscpy() function for UCS-2 strings. The behavior is
equivalent to the standard strscpy() function, just for 16-bit character
UCS-2 strings.

Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Reviewed-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230827211408.689076-2-luzmaximilian@gmail.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
This commit is contained in:
Maximilian Luz 2023-08-27 23:14:04 +02:00 committed by Bjorn Andersson
parent 0bb80ecc33
commit e4c89f9380
2 changed files with 53 additions and 0 deletions
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1
include/linux/ucs2_string.h
View File

@ -10,6 +10,7 @@ typedef u16 ucs2_char_t;
unsigned long ucs2_strnlen(const ucs2_char_t *s, size_t maxlength);
unsigned long ucs2_strlen(const ucs2_char_t *s);
unsigned long ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength);
ssize_t ucs2_strscpy(ucs2_char_t *dst, const ucs2_char_t *src, size_t count);
int ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len);
unsigned long ucs2_utf8size(const ucs2_char_t *src);

52
lib/ucs2_string.c
View File

@ -32,6 +32,58 @@ ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength)
}
EXPORT_SYMBOL(ucs2_strsize);
/**
* ucs2_strscpy() - Copy a UCS2 string into a sized buffer.
*
* @dst: Pointer to the destination buffer where to copy the string to.
* @src: Pointer to the source buffer where to copy the string from.
* @count: Size of the destination buffer, in UCS2 (16-bit) characters.
*
* Like strscpy(), only for UCS2 strings.
*
* Copy the source string @src, or as much of it as fits, into the destination
* buffer @dst. The behavior is undefined if the string buffers overlap. The
* destination buffer @dst is always NUL-terminated, unless it's zero-sized.
*
* Return: The number of characters copied into @dst (excluding the trailing
* %NUL terminator) or -E2BIG if @count is 0 or @src was truncated due to the
* destination buffer being too small.
*/
ssize_t ucs2_strscpy(ucs2_char_t *dst, const ucs2_char_t *src, size_t count)
{
long res;
/*
* Ensure that we have a valid amount of space. We need to store at
* least one NUL-character.
*/
if (count == 0 || WARN_ON_ONCE(count > INT_MAX / sizeof(*dst)))
return -E2BIG;
/*
* Copy at most 'count' characters, return early if we find a
* NUL-terminator.
*/
for (res = 0; res < count; res++) {
ucs2_char_t c;
c = src[res];
dst[res] = c;
if (!c)
return res;
}
/*
* The loop above terminated without finding a NUL-terminator,
* exceeding the 'count': Enforce proper NUL-termination and return
* error.
*/
dst[count - 1] = 0;
return -E2BIG;
}
EXPORT_SYMBOL(ucs2_strscpy);
int
ucs2_strncmp(const ucs2_char_t *a, const ucs2_char_t *b, size_t len)
{