[PATCH v2] io: fix ftw ABI on MIPS n64

[Xi Ruoyao]

On Wed, 2026-07-22 at 18:29 +0900, Andreas K. Huettel wrote:
> Am Mittwoch, 22. Juli 2026, 04:58:36 Japanische Normalzeit schrieb Xi Ruoyao:
> > On MIPS n64 off_t is same as off64_t, but struct stat is not same as
> > struct stat64 (very peculiar but see the "as tempting as it..." comment
> > in linux/mips/kernel_stat.h).  As the ftw/ftw64 callback accepts a
> > pointer to a function who accepts struct stat/stat64, for MIPS n64 we
> > must use different implementations for ftw and ftw64.
> > 
> > Thus for testing if ftw64 can be aliased to ftw, we should check
> > XSTAT_IS_XSTAT64 instead of __OFF_T_MATCHES_OFF64_T.
> > 
> > This resolves the io/tst-ftw-lnk failure observed on MIPS n64.
> 
> OK, this solves a real problem. As such we can still add it, assuming
> you get an R-B soon.

Unfortunately this breaks build on "old" 32-bit targets (where struct
stat embeds struct timespec).  I'm sending V3 after testing it on more
targets.

> Since the patch touches non-arch-specific code, however simple, I'd then
> wait with the release for a few days to allow for more testing all around.
> We do have a buffer until 1/August, luckily.
> 
> 
> > 
> > Link: https://sourceware.org/glibc/wiki/Testing/Tests/io/tst-ftw-lnk
> > Signed-off-by: Xi Ruoyao <xry111@xry111.site>
> > ---
> > 
> > Tested on x86_64-linux and mips64-linux.  No new failures were found,
> > and the aliasing of ftw ftw64 is as expected.  On x86_64:
> > 
> > $ objdump -t libc.so.6 | grep ' ftw(64)?$' -E
> > 00000000001094e0  w    F .text	000000000000000f              ftw
> > 00000000001094e0  w    F .text	000000000000000f              ftw64
> > 
> > On mips64:
> > $ objdump -t libc.so.6 | grep ' ftw(64)?$' -E
> > 000000000013a908 g     F .text	0000000000000028              ftw
> > 000000000013bff0  w    F .text	0000000000000028              ftw64
> > 
> >  io/ftw.c   | 4 ++--
> >  io/ftw64.c | 3 ++-
> >  2 files changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/io/ftw.c b/io/ftw.c
> > index ed0eeb3904..c759701372 100644
> > --- a/io/ftw.c
> > +++ b/io/ftw.c
> > @@ -16,9 +16,9 @@
> >     License along with the GNU C Library; if not, see
> >     <https://www.gnu.org/licenses/>.  */
> >  
> > -#include <sys/types.h>
> > +#include <kernel_stat.h>
> >  
> > -#ifndef __OFF_T_MATCHES_OFF64_T
> > +#if !XSTAT_IS_XSTAT64
> >  # include "ftw-common.c"
> >  
> >  versioned_symbol (libc, __new_nftw, nftw, GLIBC_2_3_3);
> > diff --git a/io/ftw64.c b/io/ftw64.c
> > index d3cd14c21a..fc36f97e7e 100644
> > --- a/io/ftw64.c
> > +++ b/io/ftw64.c
> > @@ -31,6 +31,7 @@
> >  #define ftw __rename_ftw
> >  #define nftw __rename_nftw
> >  
> > +#include <kernel_stat.h>
> >  #include <shlib-compat.h>
> >  #include "ftw-common.c"
> >  
> > @@ -44,7 +45,7 @@ versioned_symbol (libc, __new_nftw64, nftw64, GLIBC_2_3_3);
> >  compat_symbol (libc, __old_nftw64, nftw64, GLIBC_2_1);
> >  #endif
> >  
> > -#ifdef __OFF_T_MATCHES_OFF64_T
> > +#if XSTAT_IS_XSTAT64
> >  weak_alias (__ftw64, ftw)
> >  versioned_symbol (libc, __new_nftw64, nftw, GLIBC_2_3_3);
> >  # if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_3_3)
> > 
> 

-- 
Xi Ruoyao <xry111@xry111.site>