Re: [PATCH 04/10] elf: Use custom NODELETE DSO for tst-dlopenfail, tst-dlopenfail-2

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

On 18/05/2021 11:25, Florian Weimer via Libc-alpha wrote:
> Once libpthread is removed, it no longer can be used for testing.

Looks good in general, just some comments below regarding the test
change.

> ---
>  elf/Makefile                 | 11 +++++++--
>  elf/tst-dlopenfail-2.c       |  5 +---
>  elf/tst-dlopenfail.c         | 44 ++++++++++++++----------------------
>  elf/tst-dlopenfailmod2.c     |  6 ++---
>  elf/tst-dlopenfailnodelmod.c | 29 ++++++++++++++++++++++++
>  5 files changed, 59 insertions(+), 36 deletions(-)
>  create mode 100644 elf/tst-dlopenfailnodelmod.c
> 
> diff --git a/elf/Makefile b/elf/Makefile
> index 5e809dbfaa..834ec858a8 100644
> --- a/elf/Makefile
> +++ b/elf/Makefile
> @@ -334,7 +334,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
>  		tst-auditmanymod7 tst-auditmanymod8 tst-auditmanymod9 \
>  		tst-initlazyfailmod tst-finilazyfailmod \
>  		tst-dlopenfailmod1 tst-dlopenfaillinkmod tst-dlopenfailmod2 \
> -		tst-dlopenfailmod3 tst-ldconfig-ld-mod \
> +		tst-dlopenfailmod3 tst-dlopenfailnodelmod tst-ldconfig-ld-mod \
>  		tst-filterobj-flt tst-filterobj-aux tst-filterobj-filtee \
>  		tst-auditlogmod-1 tst-auditlogmod-2 tst-auditlogmod-3 \
>  		tst-single_threaded-mod1 tst-single_threaded-mod2 \
> @@ -1733,11 +1733,18 @@ LDFLAGS-tst-dlopenfailmod1.so = -Wl,--no-as-needed
>  $(objpfx)tst-dlopenfailmod1.so: \
>    $(shared-thread-library) $(objpfx)tst-dlopenfaillinkmod.so
>  LDFLAGS-tst-dlopenfaillinkmod.so = -Wl,-soname,tst-dlopenfail-missingmod.so
> -$(objpfx)tst-dlopenfailmod2.so: $(shared-thread-library)
> +$(objpfx)tst-dlopenfailmod2.so: $(objpfx)tst-dlopenfailnodelmod.so
>  $(objpfx)tst-dlopenfail-2: $(libdl)
>  $(objpfx)tst-dlopenfail-2.out: \
>    $(objpfx)tst-dlopenfailmod1.so $(objpfx)tst-dlopenfailmod2.so \
>    $(objpfx)tst-dlopenfailmod3.so

Ok.

> +# tst-dlopenfailnodelmod.so emulates how libpthread was linked.
> +$(objpfx)tst-dlopenfailnodelmod.so: $(libsupport)
> +LDFLAGS-tst-dlopenfailnodelmod.so = \
> +  -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
> +# tst-dlopenfail should export the libsupport symbols, so that
> +# tst-dlopenfailnodelmod.so uses them for error reporting.
> +LDFLAGS-tst-dlopenfail = -Wl,-E
>  
>  $(objpfx)tst-dlopen-nodelete-reloc: $(libdl)
>  $(objpfx)tst-dlopen-nodelete-reloc.out: \

Ok.

> diff --git a/elf/tst-dlopenfail-2.c b/elf/tst-dlopenfail-2.c
> index 50eed81cb0..168c4b2c7f 100644
> --- a/elf/tst-dlopenfail-2.c
> +++ b/elf/tst-dlopenfail-2.c
> @@ -28,10 +28,7 @@
>  static int
>  do_test (void)
>  {
> -  /* This test uses libpthread as the canonical NODELETE module.  If
> -     libpthread is no longer NODELETE because it has been merged into
> -     libc, the test needs to be updated.  */
> -  TEST_VERIFY (dlsym (NULL, "pthread_create") == NULL);
> +  TEST_VERIFY (dlsym (NULL, "no_delete_mod_function") == NULL);
>  
>    /* This is expected to fail because of the missing dependency.  */
>    puts ("info: attempting to load tst-dlopenfailmod1.so");

Ok.

> diff --git a/elf/tst-dlopenfail.c b/elf/tst-dlopenfail.c
> index db2b41f9b5..990e28dbce 100644
> --- a/elf/tst-dlopenfail.c
> +++ b/elf/tst-dlopenfail.c
> @@ -18,7 +18,6 @@
>  
>  #include <dlfcn.h>
>  #include <errno.h>
> -#include <gnu/lib-names.h>
>  #include <stddef.h>
>  #include <stdio.h>
>  #include <string.h>
> @@ -28,10 +27,7 @@
>  static int
>  do_test (void)
>  {
> -  /* This test uses libpthread as the canonical NODELETE module.  If
> -     libpthread is no longer NODELETE because it has been merged into
> -     libc, the test needs to be updated.  */
> -  TEST_VERIFY (dlsym (NULL, "pthread_create") == NULL);
> +  TEST_VERIFY (dlsym (NULL, "no_delete_mod_function") == NULL);
>  
>    /* This is expected to fail because of the missing dependency.  */
>    puts ("info: attempting to load tst-dlopenfailmod1.so");

Ok.

> @@ -42,36 +38,30 @@ do_test (void)
>                         " cannot open shared object file:"
>                         " No such file or directory");
>  
> -  /* Do not probe for the presence of libpthread at this point because
> -     that might trigger relocation if bug 20839 is present, obscuring
> -     a subsequent crash.  */
> +  /* Do not probe for the presence of the tst-dlopenfailnodelmod.so at
> +     this point because that might trigger relocation if bug 20839 is
> +     present, obscuring a subsequent crash.  */
>  
>    /* This is expected to succeed.  */
>    puts ("info: loading tst-dlopenfailmod2.so");
>    void *handle = xdlopen ("tst-dlopenfailmod2.so", RTLD_NOW);
> +  xdlsym (handle, "no_delete_mod_function");
>    xdlclose (handle);
>  
> -  /* libpthread should remain loaded.  */
> -  TEST_VERIFY (dlopen (LIBPTHREAD_SO, RTLD_LAZY | RTLD_NOLOAD) != NULL);
> -  TEST_VERIFY (dlsym (NULL, "pthread_create") == NULL);
> +  /* The NODELETE module should remain loaded.  */
> +  xdlopen ("tst-dlopenfailnodelmod.so", RTLD_LAZY | RTLD_NOLOAD);
> +  /* But the symbol is not in the global scope.  */

No sure if this is an improvement, the failure message will be triggered 
in the libsupport not in the test itself.

> +  TEST_VERIFY (dlsym (NULL, "no_delete_mod_function") == NULL);
>  
> -  /* We can make libpthread global, and then the symbol should become
> -     available.  */
> -  TEST_VERIFY (dlopen (LIBPTHREAD_SO, RTLD_LAZY | RTLD_GLOBAL) != NULL);
> -  TEST_VERIFY (dlsym (NULL, "pthread_create") != NULL);
> +  /* We can make tst-dlopenfailnodelmod.so global, and then the symbol
> +     should become available.  */
> +  xdlopen ("tst-dlopenfailnodelmod.so", RTLD_LAZY | RTLD_GLOBAL);
> +  void (*no_delete_mod_function) (void)
> +    = xdlsym (NULL, "no_delete_mod_function");
>  

Same as before.

> -  /* sem_open is sufficiently complex to depend on relocations.  */
> -  void *(*sem_open_ptr) (const char *, int flag, ...)
> -    = dlsym (NULL, "sem_open");
> -  if (sem_open_ptr == NULL)
> -    /* Hurd does not implement sem_open.  */
> -    puts ("warning: sem_open not found, further testing not possible");
> -  else
> -    {
> -      errno = 0;
> -      TEST_VERIFY (sem_open_ptr ("/", 0) == NULL);
> -      TEST_COMPARE (errno, EINVAL);
> -    }
> +  /* Hopefully, no_delete_mod_function is sufficiently complex to
> +     depend on relocations.  */
> +  no_delete_mod_function ();
>  
>    return 0;
>  }

Ok.

> diff --git a/elf/tst-dlopenfailmod2.c b/elf/tst-dlopenfailmod2.c
> index cd6f9cf56b..ed353f9a3c 100644
> --- a/elf/tst-dlopenfailmod2.c
> +++ b/elf/tst-dlopenfailmod2.c
> @@ -16,11 +16,11 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> -#include <pthread.h>
>  #include <stdio.h>
>  
> -/* Force linking against libpthread.  */
> -void *pthread_create_reference = pthread_create;
> +/* Force linking against tst-dlopenfailnodelmod.so.  */
> +void no_delete_mod_function (void);
> +void *function_reference = no_delete_mod_function;
>  
>  static void __attribute__ ((constructor))
>  init (void)

Ok.

> diff --git a/elf/tst-dlopenfailnodelmod.c b/elf/tst-dlopenfailnodelmod.c
> new file mode 100644
> index 0000000000..c4347b7591
> --- /dev/null
> +++ b/elf/tst-dlopenfailnodelmod.c
> @@ -0,0 +1,29 @@
> +/* NODELETE module for tst-dlopenfail, tst-dlopenfail-2.
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <support/check.h>
> +
> +/* Introduce some relocation dependencies.  */
> +const char test_string[] = "test string";
> +const char *test_string_ptr = test_string;
> +
> +void
> +no_delete_mod_function (void)
> +{
> +  TEST_COMPARE_STRING (test_string, test_string_ptr);
> +}
> 

Ok.