From e4c89f9380017b6b2e63836e2de1af8eb4535384 Mon Sep 17 00:00:00 2001 From: Maximilian Luz Date: Sun, 27 Aug 2023 23:14:04 +0200 Subject: [PATCH] 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 Reviewed-by: Bjorn Andersson Link: https://lore.kernel.org/r/20230827211408.689076-2-luzmaximilian@gmail.com Signed-off-by: Bjorn Andersson --- include/linux/ucs2_string.h | 1 + lib/ucs2_string.c | 52 +++++++++++++++++++++++++++++++++++++ 2 files changed, 53 insertions(+) diff --git a/include/linux/ucs2_string.h b/include/linux/ucs2_string.h index cf3ada3e820e..c499ae809c7d 100644 --- a/include/linux/ucs2_string.h +++ b/include/linux/ucs2_string.h @@ -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); diff --git a/lib/ucs2_string.c b/lib/ucs2_string.c index 0a559a42359b..9308bcfb2ad5 100644 --- a/lib/ucs2_string.c +++ b/lib/ucs2_string.c @@ -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) {