From: Shreeya Patel > Sent: 18 March 2021 14:13 > > On 18/03/21 7:03 pm, Shreeya Patel wrote: > > Following warning was reported by Kernel Test Robot. > > > > In function 'utf8_parse_version', > > inlined from 'utf8_load' at fs/unicode/utf8mod.c:195:7: > >>> fs/unicode/utf8mod.c:175:2: warning: 'strncpy' specified bound 12 equals > > destination size [-Wstringop-truncation] > > 175 | strncpy(version_string, version, sizeof(version_string)); > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > > > The -Wstringop-truncation warning highlights the unintended > > uses of the strncpy function that truncate the terminating NULL > > character from the source string. > > Unlike strncpy(), strscpy() always null-terminates the destination string, > > hence use strscpy() instead of strncpy(). > > > Not sure if strscpy is preferable. Just found this article > https://lwn.net/Articles/659214/ > Should I go for memcpy instead? Which length would you give memcpy() ? The compiler will moan if you try to read beyond the end of the input string. strscpy() is about the best of a bad lot. I think (I'm not sure!) that a good string copy function should return the number of bytes copies or the buffer length is truncated. Then you can do repeated: off += xxxcpy(buf + off, buflen - off, xxxxx); without any danger of writing beyond the buffer end, always getting a '\0' terminated string, and being able to detect overflow right at the end. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
