[PATCH v4 05/11] seq_buf: Add seq_buf_strlen()

[sashiko-bot at kernel.org]

> Several strlcat() call sites being converted to seq_buf need behavior
> seq_buf doesn't currently provide. The return from seq_buf_used() is
> not the length of the string in a seq_buf. Once the buffer is full or
> has overflowed it returns the buffer size, which counts the byte that
> seq_buf_str() replaces with the NUL, so a caller that needs the string
> and its length has to call seq_buf_str() and then walk the string with
> strlen().
> 
> Move the termination out of seq_buf_str() into a helper that returns
> where it put the NUL, and add seq_buf_strlen(), which terminates the
> buffer in the same way and returns that offset.
> 
> As discussed in review, don't add WARN_ON() for seq_buf_strlen() and
> drop it from seq_buf_str().
> 
> Add tests comparing seq_buf_strlen() against strlen() of seq_buf_str()
> for empty, appended, truncated, exactly full, and overflowed buffers,
> checking that seq_buf_strlen() alone terminates a full buffer, and
> checking that a zero-sized seq_buf reports an empty string from both
> accessors without touching the buffer.
> 
> Tests passed under qemu on ARCH=x86_64 with GCC 16.2.0 and CONFIG_KASAN=y,
> and on big-endian ARCH=s390 with GCC s390x-linux-gnu 16.2.0.
> 
> Assisted-by: LLM
> Reviewed-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> Signed-off-by: Kees Cook <kees at kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003035906.too.263-kees@kernel.org?part=5