Hi Thomas, On Fri, Mar 13, 2026 at 09:26:28PM +0100, Thomas Weißschuh wrote: > Add support for the GNU extensions 'program_invocation_name' and > 'program_invocation_short_name'. These are useful to print error > messages, which by convention include the program name. > > As these are global variables which take up memory even if not used, > similar to 'errno', gate them behind NOLIBC_IGNORE_ERRNO. > > Signed-off-by: Thomas Weißschuh <[email protected]> > --- > tools/include/nolibc/crt.h | 26 ++++++++++++++++++++++ > tools/include/nolibc/errno.h | 2 ++ > tools/testing/selftests/nolibc/nolibc-test.c | 33 > ++++++++++++++++++++++++++++ > 3 files changed, 61 insertions(+) > > diff --git a/tools/include/nolibc/crt.h b/tools/include/nolibc/crt.h > index d9262998dae9..842f86e41f2f 100644 > --- a/tools/include/nolibc/crt.h > +++ b/tools/include/nolibc/crt.h > @@ -17,6 +17,7 @@ const unsigned long *_auxv __attribute__((weak)); > void _start(void); > static void __stack_chk_init(void); > static void exit(int); > +static char *strrchr(const char *s, int c); > > extern void (*const __preinit_array_start[])(int, char **, char**) > __attribute__((weak)); > extern void (*const __preinit_array_end[])(int, char **, char**) > __attribute__((weak)); > @@ -27,6 +28,24 @@ extern void (*const __init_array_end[])(int, char **, > char**) __attribute__((wea > extern void (*const __fini_array_start[])(void) __attribute__((weak)); > extern void (*const __fini_array_end[])(void) __attribute__((weak)); > > +extern char *program_invocation_name __attribute__((weak)); > +extern char *program_invocation_short_name __attribute__((weak)); > + > +static __inline__ > +char *__nolibc_program_invocation_short_name(char *long_name) > +{ > + char *short_name; > + > + if (!long_name) > + return NULL; > + > + short_name = strrchr(long_name, '/'); > + if (!short_name || !short_name[0]) > + return NULL;
Here it should return long_name, not NULL, since you want a valid name to use later. I'm seeing it passed to strcmp() for example. Also because of this, I'm wondering for the first test about !long_name. Either we consider that it's not possible to have a NULL long_name and we don't need to test for it, or we consider it is valid, and we should return a non-null string (e.g. "") so that the rest of the program survives it. Both approaches are fine to me, but IMHO testing for NULL to return a NULL that will crash the program later instead of just now is not very useful. Maybe returning the empty string is still slightly better because it allows well-designed programs that check their argc before using argv[0] to survive. Cheers, Willy
