Re: [PATCH v2] posix/tst-rfc3484: Fix compile failure linking to local __stat64

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

On 22/01/2021 20:05, Stafford Horne via Libc-alpha wrote:
> After 04986243d1 ("Remove internal usage of extensible stat functions")
> linking the __stat64 symbol in getaddrinfo for this test fails with the
> below error:
> 
>     /home/shorne/work/gnu-toolchain/local/lib/gcc/or1k-smh-linux-gnu/11.0.0/../../../../or1k-smh-linux-gnu/bin/ld: /home/shorne/work/gnu-toolchain/build-glibc/posix/tst-rfc3484.o: in function `gaiconf_reload':
>     /home/shorne/work/gnu-toolchain/glibc/posix/../sysdeps/posix/getaddrinfo.c:2136: undefined reference to `__stat64'
>     collect2: error: ld returned 1 exit status
> 
> This is because __stat64 is a local symbol, the test includes the
> getaddrinfo directly and fails to link against the local symbol.  Fix
> this by setting up an alias to the global stat64 symbol name like is
> done for other local symbol usage.

I am trying to understand why I haven't see a similar issue for riscv32,
since it does not provide any xstat symbols.  It seems that for tests,
I am not seeing any __stat64 call, but rather __fstat64 ones:

  $ riscv32-glibc-linux-gnu-objdump -t posix/tst-rfc3484.o | grep stat
  00000000         *UND*  00000000 __fstat64
  $ riscv32-glibc-linux-gnu-objdump -t posix/tst-rfc3484-2.o | grep stat
  00000000         *UND*  00000000 __fstat64
  $ riscv32-glibc-linux-gnu-objdump -t posix/tst-rfc3484-3.o | grep stat
  00000000         *UND*  00000000 __fstat64

It comes from gaiconf_init and I am not sure why __stat64 call from
gaiconf_reload is not being generated (maybe this is being optimized
out).

And the __fstat64 seems to not generate a linking error because is being
exported by libc.so in GLIBC_PRIVATE namespace (due 8ed005daf0ab03). I
added this because of the libpthread usage, but it seems we don't
actually required it.  For 2.34 I plan to send:

diff --git a/io/Versions b/io/Versions
index 49c4d2d40a..4ffafd4bde 100644
--- a/io/Versions
+++ b/io/Versions
@@ -145,6 +145,5 @@ libc {
     __file_change_detection_for_stat;
     __file_change_detection_for_path;
     __file_change_detection_for_fp;
-    __fstat64;
   }
 }
diff --git a/sysdeps/pthread/sem_open.c b/sysdeps/pthread/sem_open.c
index b0b722121d..b3b4de779b 100644
--- a/sysdeps/pthread/sem_open.c
+++ b/sysdeps/pthread/sem_open.c
@@ -68,7 +68,7 @@ check_add_mapping (const char *name, size_t namelen, int fd, sem_t *existing)
 
   /* Get the information about the file.  */
   struct stat64 st;
-  if (__fstat64 (fd, &st) == 0)
+  if (fstat64 (fd, &st) == 0)
     {
       /* Get the lock.  */
       lll_lock (__sem_mappings_lock, LLL_PRIVATE);

To remove the __fstat64 requirement on GLIBC_PRIVATE.

This patch looks ok on 2.34 opens.

> ---
> Changes since v1:
>  - Fix typo in commit s/list/like/
>  - Address other tests that fail with the same issue
> 
>  posix/tst-rfc3484-2.c | 1 +
>  posix/tst-rfc3484-3.c | 1 +
>  posix/tst-rfc3484.c   | 1 +
>  3 files changed, 3 insertions(+)
> 
> diff --git a/posix/tst-rfc3484-2.c b/posix/tst-rfc3484-2.c
> index 5f5ada9420..ce8ccd5f38 100644
> --- a/posix/tst-rfc3484-2.c
> +++ b/posix/tst-rfc3484-2.c
> @@ -11,6 +11,7 @@
>  #define __gethostbyaddr_r gethostbyaddr_r
>  #define __gethostbyname2_r gethostbyname2_r
>  #define __qsort_r qsort_r
> +#define __stat64 stat64
>  
>  void
>  attribute_hidden
> diff --git a/posix/tst-rfc3484-3.c b/posix/tst-rfc3484-3.c
> index d9ec5cc851..ecb163963f 100644
> --- a/posix/tst-rfc3484-3.c
> +++ b/posix/tst-rfc3484-3.c
> @@ -11,6 +11,7 @@
>  #define __gethostbyaddr_r gethostbyaddr_r
>  #define __gethostbyname2_r gethostbyname2_r
>  #define __qsort_r qsort_r
> +#define __stat64 stat64
>  
>  void
>  attribute_hidden
> diff --git a/posix/tst-rfc3484.c b/posix/tst-rfc3484.c
> index 97d065b6bf..3b2052eb54 100644
> --- a/posix/tst-rfc3484.c
> +++ b/posix/tst-rfc3484.c
> @@ -11,6 +11,7 @@
>  #define __gethostbyaddr_r gethostbyaddr_r
>  #define __gethostbyname2_r gethostbyname2_r
>  #define __qsort_r qsort_r
> +#define __stat64 stat64
>  
>  void
>  attribute_hidden
>