clang generates internal calls for some _chk symbol, so add internal
aliases for them, and stub some with rtld-stubbed-symbols to avoid
ld.so linker issues.

Reviewed-by: Sam James <sam@gentoo.org>

C23 makes various standard library functions, that return a pointer
into an input array, into macros that return a pointer to const when
the relevant argument passed to the macro is a pointer to const.  (The
requirement is for macros, with the existing function types applying
when macro expansion is suppressed.  When a null pointer constant is
passed, such as integer 0, that's the same as a pointer to non-const.)

Implement this feature.  This only applies to C, not C++, since such
macros are not an appropriate way of doing this for C++ and all the
affected functions other than bsearch have overloads to implement an
equivalent feature for C++ anyway.  Nothing is done to apply such a
change to any non-C23 functions with the same property of returning a
pointer into an input array.

The feature is also disabled when _LIBC is defined, since there are
various places in glibc that either redefine these identifiers as
macros, or define the functions themselves, and would need changing to
work in the presence of these macro definitions.  A natural question
is whether we should in fact change those places and not disable the
macro definitions for _LIBC.  If so, we'd need a solution for the
places in glibc that define the macro *before* including the relevant
header (in order in effect to disable the header declaration of the
function by renaming that declaration).

One testcase has #undef added to avoid conflicting with this feature
and another has const added; -Wno-discarded-qualifiers is added for
building zic (but could be removed once there's a new upstream tzcode
release that's const-safe with this C23 change and glibc has updated
to code from that new release).  Probably other places in glibc proper
would need const added if we remove the _LIBC conditionals.

Another question would be whether some GCC extension should be added
to support this feature better with macros that only expand each
argument once (as well as reducing duplication of diagnostics for bad
usages such as non-pointer and pointer-to-volatile-qualfied
arguments).

Tested for x86_64.

The setrlimit(2) function returns 0 on success and -1 on error, but
several test files were incorrectly checking for a return value of 1
to detect errors.  This means the error checks would never trigger,
causing tests to continue silently even when setrlimit() failed.

This commit fixes the error checks in five files to correctly test
for -1, matching both the documented behavior and the pattern used
correctly in other parts of the codebase.

Signed-off-by: Osama Abdelkader <osama.abdelkader@gmail.com>
Reviewed-by: Collin Funk <collin.funk1@gmail.com>

Add the C23 memset_explicit function to glibc.  Everything here is
closely based on the approach taken for explicit_bzero.  This includes
the bits that relate to internal uses of explicit_bzero within glibc
(although we don't currently have any such internal uses of
memset_explicit), and also includes the nonnull attribute (when we
move to nonnull_if_nonzero for various functions following C2y, this
function should be included in that change).

The function is declared both for __USE_MISC and for __GLIBC_USE (ISOC23)
(so by default not just for compilers defaulting to C23 mode).

Tested for x86_64 and x86.

And add extra checks to enable for binutils 2.45 and if the architecture
explicitly enables it.  When SFrame is disabled, all the related code
is also not enabled for backtrace() and _dl_find_object(), so SFrame
backtracking is not used even if the binary has the SFrame segment.

This patch also adds some other related fixes:

  * Fixed an issue with AC_CHECK_PROG_VER, where the READELF_SFRAME
    usage prevented specifying a different readelf through READELF
    environment variable at configure time.

  * Add an extra arch-specific internal definition,
    libc_cv_support_sframe, to disable --enable-sframe on architectures
    that have binutils but not glibc support (s390x).

  * Renamed the tests without the .sframe segment and move the
    tst-backtrace1 from pthread to debug.

  * Use the built compiler strip to remove the .sframe segment,
    instead of the system one (which might not support SFrame).

Checked on x86_64-linux-gnu and aarch64-linux-gnu.

Reviewed-by: Sam James <sam@gentoo.org>

This test requires relro_format be placed in the PT_GNU_RELRO segment.
The ELF linker enables -z relro support by default on all Linux targets
except FRV, HPPA, IA64 and MIPS. On these targets, we need to explicitly
link with -z relro to place relro_format in the PT_GNU_RELRO segment.

Signed-off-by: John David Anglin <dave.anglin@bell.net>

The _dl_read_only_area function in the uninitialized ld.so after
static dlopen is not able to find anything.  Instead, we need to
redirect to the code from the statically linked main program.

Fixes commit d60fffe28a46b2a41fc308c1804ff02375d27408 ("debug:
Improve '%n' fortify detection (BZ 30932)").

Reviewed-by: Adhemerval Zanella Netto  <adhemerval.zanella@linaro.org>

The test intends to load tst-sprintf-fortify-rdonly-dlopen.so via
dlopen, and directly linking against it prevents that.

Reviewed-by: Adhemerval Zanella Netto  <adhemerval.zanella@linaro.org>

When SFrame is enabled, we need to tests DW backtracer as well. Do
this by executing the same backtrace tests with .sframe section
stripped.

Signed-off-by: Claudiu Zissulescu <claudiu.zissulescu-ianculescu@oracle.com>
Reviewed-by: DJ Delorie <dj@redhat.com>