Re: [dpdk-dev] [PATCH v2 1/7] eal: add wrappers for POSIX string functions

[Thomas Monjalon <thomas@monjalon.net>]

27/02/2021 21:23, Dmitry Kozlyuk:
> 2021-02-23 09:45, Bruce Richardson:
> > On Tue, Feb 23, 2021 at 01:57:50AM +0300, Dmitry Kozlyuk wrote:
> > > 2021-02-22 14:26, Bruce Richardson:  
> > > > As you say, though, the main issue will be whether we have instances in
> > > > public header files or not. I would hope that no static inline functions in
> > > > DPDK use any of the functions in question, but I'm not sure. Perhaps if
> > > > there are instances in public headers those could be reworked to not use
> > > > the problematic functions.  
> > > 
> > > No instances of strdup(), strncasecmp(), or strtok_r() in any DPDK headers.
> > >   
> > > > For any functions, such as strdup, which are not in a public header I would
> > > > suggest the following as a possible start point, based off what was done
> > > > for strlcpy.
> > > > 
> > > > * In DPDK (probably EAL), define an rte_strdup function for use as a
> > > >   fallback.
> > > > * Inside the meson build scripts, use "cc.has_function()" to check if the
> > > >   regular strdup function is available. If not, then add "-DRTE_NO_STRDUP"
> > > >   to the c_args for DPDK building
> > > > * Inside our DPDK header (rte_string_fns.h in the strdup case), we can add
> > > >   a conditional define such as:
> > > >    #ifdef RTE_NO_STRDUP
> > > >    #define strdup(s) rte_strdup(s)
> > > >    #endif
> > > > 
> > > > Thoughts on this?  
> > > 
> > > Looks good to me, I can rework the patchset like so.
> > > 
> > > Policy considerations:
> > > 1. The approach only applies to platform-agnostic functions, like str*().
> > >    Functions like sleep() still belong to librte_eal.
> > > 2. Deprecated functions, like index(3p), should be replaced
> > >    with alternatives suggested by the standard.
> > > 3. If a standard C11 alternative is available, it should be used.
> > >    This mostly applies to types, like u_int32 -> uint32_t
> > >    (it's even in DPDK coding style already, isn't it?).
> > > 
> > > A nit: RTE_NO_XXX -> RTE_HAS_XXX (for consistency with existing macros)?  
> > 
> > Sure, thanks.
> 
> There's a meson issue with `cc.has_function()`:
> https://github.com/mesonbuild/meson/issues/5628

The meson issue can be fixed or workarounded probably.
Is it the reason for the RTE_INTERNAL proposal below?

> What if we just define RTE_INTERNAL for librte_eal/windows/include/rte_os.h
> (and other public headers if need be) to distinguish the case when it's used
> from within DPDK?

I'm not sure to follow the need for RTE_INTERNAL.

In general, 3 guidelines:
	- avoid inline functions in public headers
	- mark exported internal functions with __rte_internal and in version.map
	- export internal functions in a separate file