Messages in this thread | | | Date | Fri, 4 Aug 2023 21:23:43 +0200 | Subject | Re: [PATCH v5 1/3] lib/ucs2_string: Add UCS-2 strscpy function | From | Maximilian Luz <> |
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On 8/4/23 10:18, Kees Cook wrote: > On Sun, Jul 30, 2023 at 06:19:02PM +0200, Maximilian Luz wrote: >> 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> >> --- >> >> Changes in v5: >> - Add ucs2_strscpy() instead of ucs2_strlcpy() >> >> Patch introduced in v4. >> >> --- >> include/linux/ucs2_string.h | 1 + >> lib/ucs2_string.c | 35 +++++++++++++++++++++++++++++++++++ >> 2 files changed, 36 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..b608129fcbdc 100644 >> --- a/lib/ucs2_string.c >> +++ b/lib/ucs2_string.c >> @@ -32,6 +32,41 @@ ucs2_strsize(const ucs2_char_t *data, unsigned long maxlength) >> } >> EXPORT_SYMBOL(ucs2_strsize); >> >> +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)) > > Is "count" a measure of bytes or characters? It seems to be characters. > can you please add some kern-doc for this function to clarify this. > Also, I wonder if the above check should be "count > INT_MAX / 2" since > the INT_MAX is, generally, done in byte counts.
Count is a measure of characters. I'll add a doc-comment.
Regarding INT_MAX / 2: I'm fine with either. I'd change it to INT_MAX / sizeof(*dst) if you say it's generally enforced in bytes.
>> + return -E2BIG; >> + >> + /* >> + * Copy at most 'count' bytes, return early if we find a > > If "count" is characters, this comment should not say "bytes". :)
Correct. Will fix this.
>> + * 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) >> { >> -- >> 2.41.0 >> > > Otherwise looks good to me!
Thanks!
Regards Max
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