[PATCH] posix: Move environ helper variables next to environ definition (bug 32541)

[H.J. Lu]

On Sat, Mar 8, 2025 at 12:33 AM Florian Weimer <fweimer@redhat.com> wrote:
>
> This helps with statically interposing getenv.
>
> Updates commit 7a61e7f557a97ab597d6fca5e2d1f13f65685c61
> ("stdlib: Make getenv thread-safe in more cases").
>
> ---
>  posix/environ.c            |  4 ++++
>  stdlib/Makefile            |  2 ++
>  stdlib/getenv.c            |  3 ---
>  stdlib/tst-getenv-static.c | 38 ++++++++++++++++++++++++++++++++++++++
>  4 files changed, 44 insertions(+), 3 deletions(-)
>
> diff --git a/posix/environ.c b/posix/environ.c
> index a0ed0d80ea..924effe3cd 100644
> --- a/posix/environ.c
> +++ b/posix/environ.c
> @@ -2,6 +2,7 @@
>
>  #include <unistd.h>
>  #include <stddef.h>
> +#include <stdlib/setenv.h>
>
>  /* This must be initialized; we cannot have a weak alias into bss.  */
>  char **__environ = NULL;
> @@ -10,3 +11,6 @@ weak_alias (__environ, environ)
>  /* The SVR4 ABI says `_environ' will be the name to use
>     in case the user overrides the weak alias `environ'.  */
>  weak_alias (__environ, _environ)
> +
> +struct environ_array *__environ_array_list;
> +environ_counter __environ_counter;
> diff --git a/stdlib/Makefile b/stdlib/Makefile
> index 1c4fa2382f..c9c8f702a2 100644
> --- a/stdlib/Makefile
> +++ b/stdlib/Makefile
> @@ -282,6 +282,7 @@ tests := \
>    tst-environ-change-3 \
>    tst-environ-change-4 \
>    tst-getenv-signal \
> +  tst-getenv-static \
>    tst-getenv-thread \
>    tst-getenv-unsetenv \
>    tst-getrandom \
> @@ -377,6 +378,7 @@ tests-internal := \
>    # tests-internal
>
>  tests-static := \
> +  tst-getenv-static \
>    tst-secure-getenv \
>    # tests-static
>
> diff --git a/stdlib/getenv.c b/stdlib/getenv.c
> index 5e7212cca6..1a7b0bfc06 100644
> --- a/stdlib/getenv.c
> +++ b/stdlib/getenv.c
> @@ -20,9 +20,6 @@
>  #include <string.h>
>  #include <unistd.h>
>
> -struct environ_array *__environ_array_list;
> -environ_counter __environ_counter;
> -
>  char *
>  getenv (const char *name)
>  {
> diff --git a/stdlib/tst-getenv-static.c b/stdlib/tst-getenv-static.c
> new file mode 100644
> index 0000000000..f5f484c83a
> --- /dev/null
> +++ b/stdlib/tst-getenv-static.c
> @@ -0,0 +1,38 @@
> +/* Static interposition of getenv (bug 32541).
> +   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 <stdlib.h>
> +#include <support/check.h>
> +
> +/* Some programs try to interpose getenv for their own use (not
> +   glibc's internal use).  Make sure that this is possible without
> +   introducing linker failures due to duplicate symbols.  */
> +
> +char *
> +getenv (const char *ignored)
> +{
> +  return NULL;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  TEST_COMPARE_STRING (getenv ("PATH"), NULL);
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>
>
> base-commit: 59dc232df277c21239c357e3519682c26e182cd7
>

LGTM.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

Thanks.

-- 
H.J.