Re: [PATCH 1/2] Doc: deprecated.rst: add strlcat()

[Manuel Ebner <manuelebner@mailbox.org>]

On Tue, 2026-05-12 at 11:52 +0300, Jani Nikula wrote:
> On Sun, 10 May 2026, Manuel Ebner <manuelebner@mailbox.org> wrote:
> > add strlcat and alternatives
> 
> You'd think it's the strlcat() definition that needs a comment above it
> saying it's deprecated. I don't think folks really look at
> deprecated.rst.

arch/s390/lib/string.c
lib/string.c
and
tools/include/nolibc/string.h

do not mentions anything about obsolete.

include/linux/fortify-string.h has 

 /* Defined after fortified strlen() to reuse it. */
 extern size_t __real_strlcat(char *p, const char *q, size_t avail) __RENAME(strlcat);
 /**
  * strlcat - Append a string to an existing string
  * [...]
  * Do not use this function. While FORTIFY_SOURCE tries to avoid
  * read and write overflows, this is only possible when the sizes
  * of @p and @q are known to the compiler. Prefer building the
  * string with formatting, via scnprintf(), seq_buf, or similar.

should i add this to the former three files?

Manuel

> 
> BR,
> Jani.
> 
> > 
> > Signed-off-by: Manuel Ebner <manuelebner@mailbox.org>
> > ---
> >  Documentation/process/deprecated.rst | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/Documentation/process/deprecated.rst b/Documentation/process/deprecated.rst
> > index fed56864d036..b8a65c19796c 100644
> > --- a/Documentation/process/deprecated.rst
> > +++ b/Documentation/process/deprecated.rst
> > @@ -162,6 +162,12 @@ if a source string is not NUL-terminated. The safe replacement is
> > strscpy(),
> >  though care must be given to any cases where the return value of strlcpy()
> >  is used, since strscpy() will return negative errno values when it truncates.
> >  
> > +strlcat()
> > +---------
> > +strlcat() must re-scan the destination string from the beginning on each
> > +call (O(n^2) behavior). Alternatives are seq_buf_puts(), seq_buf_printf(),
> > +snprintf() and scnprintf()
> > +
> >  %p format specifier
> >  -------------------
> >  Traditionally, using "%p" in format strings would lead to regular address
>