It adds useful functions for tests that use struct timespec.
Checked on x86_64-linux-gnu and i686-linux-gnu.
* support/timespec.h: New file. Provide timespec helper functions
along with macros in the style of those in check.h.
* support/timespec.c: New file. Implement check functions declared
in support/timespec.h.
* support/timespec-add.c: New file from gnulib containing
timespec_add implementation that handles overflow.
* support/timespec-sub.c: New file from gnulib containing
timespec_sub implementation that handles overflow.
* support/README: Mention timespec.h.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
* support/xclock_gettime.c (xclock_gettime): New file. Provide
clock_gettime wrapper for use in tests that fails the test rather
than returning failure.
* support/xtime.h: New file to declare xclock_gettime.
* support/Makefile: Add xclock_gettime.c.
* support/README: Mention xtime.h.
Its API is similar to support_capture_subprocess, but rather creates a
new process based on the input path and arguments. Under the hoods it
uses posix_spawn to create the new process.
It also allows the use of other support_capture_* functions to check
for expected results and free the resources.
Checked on x86_64-linux-gnu.
* support/Makefile (libsupport-routines): Add support_subprocess,
xposix_spawn, xposix_spawn_file_actions_addclose, and
xposix_spawn_file_actions_adddup2.
(tst-support_capture_subprocess-ARGS): New rule.
* support/capture_subprocess.h (support_capture_subprogram): New
prototype.
* support/support_capture_subprocess.c (support_capture_subprocess):
Refactor to use support_subprocess and support_capture_poll.
(support_capture_subprogram): New function.
* support/tst-support_capture_subprocess.c (write_mode_to_str,
str_to_write_mode, test_common, parse_int, handle_restart,
do_subprocess, do_subprogram, do_multiple_tests): New functions.
(do_test): Add support_capture_subprogram tests.
* support/subprocess.h: New file.
* support/support_subprocess.c: Likewise.
* support/xposix_spawn.c: Likewise.
* support/xposix_spawn_file_actions_addclose.c: Likewise.
* support/xposix_spawn_file_actions_adddup2.c: Likewise.
* support/xspawn.h: Likewise.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
One of the implicit-fallthrough warnings from compiling glibc with
-Wextra appears to indicate an actual bug: the test-container code
could fall through inappropriately if execlp returns (which only
occurs on error). This patch adds appropriate error handling in this
case to avoid that fall-through.
Tested for x86_64.
* support/test-container.c (recursive_remove): Use FAIL_EXIT1 if
execlp returns.
The alignment of TLS variables is wrong if accessed from within a thread
for architectures with tls variant TLS_TCB_AT_TP.
For the main thread the static tls data is properly aligned.
For other threads the alignment depends on the alignment of the thread
pointer as the static tls data is located relative to this pointer.
This patch adds this alignment for TLS_TCB_AT_TP variants in the same way
as it is already done for TLS_DTV_AT_TP. The thread pointer is also already
properly aligned if the user provides its own stack for the new thread.
This patch extends the testcase nptl/tst-tls1.c in order to check the
alignment of the tls variables and it adds a pthread_create invocation
with a user provided stack.
The test itself is migrated from test-skeleton.c to test-driver.c
and the missing support functions xpthread_attr_setstack and xposix_memalign
are added.
ChangeLog:
[BZ #23403]
* nptl/allocatestack.c (allocate_stack): Align pointer pd for
TLS_TCB_AT_TP tls variant.
* nptl/tst-tls1.c: Migrate to support/test-driver.c.
Add alignment checks.
* support/Makefile (libsupport-routines): Add xposix_memalign and
xpthread_setstack.
* support/support.h: Add xposix_memalign.
* support/xthread.h: Add xpthread_attr_setstack.
* support/xposix_memalign.c: New File.
* support/xpthread_attr_setstack.c: Likewise.
For a full analysis of both the pthread_rwlock_tryrdlock() stall
and the pthread_rwlock_trywrlock() stall see:
https://sourceware.org/bugzilla/show_bug.cgi?id=23844#c14
In the pthread_rwlock_trydlock() function we fail to inspect for
PTHREAD_RWLOCK_FUTEX_USED in __wrphase_futex and wake the waiting
readers.
In the pthread_rwlock_trywrlock() function we write 1 to
__wrphase_futex and loose the setting of the PTHREAD_RWLOCK_FUTEX_USED
bit, again failing to wake waiting readers during unlock.
The fix in the case of pthread_rwlock_trydlock() is to check for
PTHREAD_RWLOCK_FUTEX_USED and wake the readers.
The fix in the case of pthread_rwlock_trywrlock() is to only write
1 to __wrphase_futex if we installed the write phase, since all other
readers would be spinning waiting for this step.
We add two new tests, one exercises the stall for
pthread_rwlock_trywrlock() which is easy to exercise, and one exercises
the stall for pthread_rwlock_trydlock() which is harder to exercise.
The pthread_rwlock_trywrlock() test fails consistently without the fix,
and passes after. The pthread_rwlock_tryrdlock() test fails roughly
5-10% of the time without the fix, and passes all the time after.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Signed-off-by: Torvald Riegel <triegel@redhat.com>
Signed-off-by: Rik Prohaska <prohaska7@gmail.com>
Co-authored-by: Torvald Riegel <triegel@redhat.com>
Co-authored-by: Rik Prohaska <prohaska7@gmail.com>
If /etc/aliases ends with a continuation line (a line that starts
with whitespace) which does not have a trailing newline character,
the file parser would crash due to a null pointer dereference.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Hurd does not support MAP_NORESERVE and MAP_STACK.
Checked on i686-gnu build.
* support/xsigstack.c (MAP_NORESERVE, MAP_STACK): Define if they
are not defined.
There is general agreement that the very short list of things that ISO
C says you can do in an async signal handler should all work when the
handler is running on an alternate signal stack with only MINSIGSTKSZ
space. This patch adds tests to make sure those things do work.
To facilitate this, there is a new set of test support routines for
setting up alternate signal stacks; see support/xsignal.h for the API.
* support/xsignal.h (xalloc_sigstack, xfree_sigstack)
(xget_sigstack_location): New test support functions.
* support/xsigstack.c: New file, implementing them.
* support/tst-xsigstack.c: New test for them.
* support/Makefile: Update.
* signal/tst-minsigstksz-1.c
* signal/tst-minsigstksz-2.c
* signal/tst-minsigstksz-3.c
* signal/tst-minsigstksz-3a.c
* signal/tst-minsigstksz-4.c: New tests.
* signal/Makefile: Run them.
During postclean.req testing it was found that the fork in the
parent process (after the unshare syscall) would fail with ENOMEM
(see recursive_remove() in test-container.c). While failing with
ENOMEM is certainly unexpected, it is simply easier to refactor
the design and have the parent remain outside of the namespace.
This change moves the postclean.req processing to a distinct
process (the parent) that then forks the test process (which will
have to fork once more to complete uid/gid transitions). When the
test process exists the cleanup process will ensure all files are
deleted when a post clean is requested.
Signed-off-by: DJ Delorie <dj@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
[BZ #23948]
* support/test-container.c: Move postclean step to before we
change namespaces.
Signal zero does not terminate a process, so it is safe to use negative
values for signal numbers.
Adjust libio/tst-vtables-common.c to use this new functionality,
instead of determining the termination status for a signal indirectly.
This is sometimes useful to determine if a test truly got stuck, or if
it was making progress (logging information to standard output) and
was merely slow to finish.
Fix the following on 32 bits targets:
support_test_compare_string.c: In function ‘support_test_compare_string’:
support_test_compare_string.c:80:37: error: format ‘%lu’ expects argument of
type ‘long unsigned int’, but argument 2 has type ‘size_t’ {aka ‘unsigned int’}
[-Werror=format=]
printf (" string length: %lu bytes\n", left_length);
~~^ ~~~~~~~~~~~
%u
Checked on arm-linux-gnueabihf.
* support/support_test_compare_string.c
(support_test_compare_string): Fix printf format.
On systems without enough random-access memory, stdlib/test-bz22786
will go deeply into swap and time out, even with a substantial
TIMEOUTFACTOR. This commit adds a facility to construct repeating
strings with alias mappings, so that the requirement for physical
memory, and uses it in stdlib/test-bz22786.
The test-container.c file assumes that ld.so is always named
something like /elf/ld-linux-*.
But e.g. on s390x it is named ld64.so.1 or ld.so.1 on s390.
There are other architectures like power or mips with similar names.
This patch introduces the new global variable support_objdir_elf_ldso
which contains the absolute path to the runtime linker used by the
testsuite, e.g. OBJDIR_PATH/elf/ld-linux-x86-64.so.2.
The check in test-container.c is now comparing against this path.
Without this patch, test-container.c is searching invalid files / directories
and fails to find glibc/nss/tst-nss-test3.root/tst-nss-test3.script.
Then the test tst-nss-test3 fails!
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
ChangeLog:
* support/support.h (support_objdir_elf_ldso): New variable.
* support/support_paths.c (support_objdir_elf_ldso): Likewise.
* support/Makefile (CFLAGS-support_paths.c): Add definition
for OBJDIR_ELF_LDSO_PATH.
* support/test-container.c (main): Search for the ld.so
which is also used by the testsuite.
copy_file_range can't be used to copy a file from glibc source directory
to glibc build directory since they may be on different filesystems.
This patch adds xcopy_file_range for cross-device copy.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
[BZ #23597]
* support/Makefile (libsupport-routines): Add
support_copy_file_range and xcopy_file_range.
* support/support.h: Include <sys/types.h>.
(support_copy_file_range): New prototype.
* support/support_copy_file_range.c: New file. Copied and
modified from io/copy_file_range-compat.c.
* support/test-container.c (copy_one_file): Call xcopy_file_rang
instead of copy_file_range.
* support/xcopy_file_range.c: New file.
* support/xunistd.h (xcopy_file_range): New prototype.
C99 specifies that the EOF condition on a file is "sticky": once EOF
has been encountered, all subsequent reads should continue to return
EOF until the file is closed or something clears the "end-of-file
indicator" (e.g. fseek, clearerr). This is arguably a change from
C89, where the wording was ambiguous; the BSDs always had sticky EOF,
but the System V lineage would attempt to read from the underlying fd
again. GNU libc has followed System V for as long as we've been
using libio, but nowadays C99 conformance and BSD compatibility are
more important than System V compatibility.
You might wonder if changing the _underflow impls is sufficient to
apply the C99 semantics to all of the many stdio functions that
perform input. It should be enough to cover all paths to _IO_SYSREAD,
and the only other functions that call _IO_SYSREAD are the _seekoff
impls, which is OK because seeking clears EOF, and the _xsgetn impls,
which, as far as I can tell, are unused within glibc.
The test programs in this patch use a pseudoterminal to set up the
necessary conditions. To facilitate this I added a new test-support
function that sets up a pair of pty file descriptors for you; it's
almost the same as BSD openpty, the only differences are that it
allocates the optionally-returned tty pathname with malloc, and that
it crashes if anything goes wrong.
[BZ #1190]
[BZ #19476]
* libio/fileops.c (_IO_new_file_underflow): Return EOF immediately
if the _IO_EOF_SEEN bit is already set; update commentary.
* libio/oldfileops.c (_IO_old_file_underflow): Likewise.
* libio/wfileops.c (_IO_wfile_underflow): Likewise.
* support/support_openpty.c, support/tty.h: New files.
* support/Makefile (libsupport-routines): Add support_openpty.
* libio/tst-fgetc-after-eof.c, wcsmbs/test-fgetwc-after-eof.c:
New test cases.
* libio/Makefile (tests): Add tst-fgetc-after-eof.
* wcsmbs/Makefile (tests): Add tst-fgetwc-after-eof.
The old implementation based on hsearch_r used an ad-hoc C string
encoding and produced an incorrect format on the wire for domain
names which contained bytes which needed escaping when printed.
This commit switches to ns_name_pton for the wire format conversion
(now that we have separate tests for it) and uses a tsearch tree
with a suitable comparison function to locate compression targets.
The previous implementation of the TEST_COMPARE macro would fail
to compile code like this:
int ret = res_send (query, sizeof (query), buf, sizeof (buf));
TEST_COMPARE (ret,
sizeof (query)
+ 2 /* Compression reference. */
+ 2 + 2 + 4 + 2 /* Type, class, TTL, RDATA length. */
+ 1 /* Pascal-style string length. */
+ strlen (expected_name));
This resulted in a failed static assertion, "integer conversions
may alter sign of operands". A user of the TEST_COMPARE would have
to add a cast to fix this.
This patch reverts to the original proposed solution of a run-time
check, making TEST_COMPARE usable for comparisons of numbers with
types with different signedness in more contexts.
This adds system call wrappers for pkey_alloc, pkey_free, pkey_mprotect,
and x86-64 implementations of pkey_get and pkey_set, which abstract over
the PKRU CPU register and hide the actual number of memory protection
keys supported by the CPU. pkey_mprotect with a -1 key is implemented
using mprotect, so it will work even if the kernel does not support the
pkey_mprotect system call.
The system call wrapers use unsigned int instead of unsigned long for
parameters, so that no special treatment for x32 is needed. The flags
argument is currently unused, and the access rights bit mask is limited
to two bits by the current PKRU register layout anyway.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
The requirement to write "deny" to /proc/<pid>/setgroups for a given user
namespace before being able to write a gid mapping was introduced in Linux
3.19. Before that this requirement including the file did not exist.
So don't fail when errno == ENOENT.
System defaults vary, and a mere unshare (CLONE_NEWNS) (which is part of
support_become_root) is no longer sufficient.
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
create_temp_file automatically supplies the test directory and the
XXXXXX suffix. support_create_temp_directory required the caller to
specify them, which was confusing.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Without UID/GID maps, file creation will file with EOVERFLOW.
This patch is based on DJ Delorie's work on container testing.
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
server_thread_udp_process_one already takes care of calling sendto()
instead of xsendto to be able to ignore the case where the client has
closed the socket. Depending on the TCP/IP stack behavior, this error
could be notified later through recvfrom(), so we need to ignore it
there too.
* support/resolv_test.c (server_thread_udp_process_one): Call recvfrom
instead of xrecvfrom, and ignore ECONNREFUSED errors.
Without this fix, the rwlock can fail to execute the explicit hand-over
in certain cases (e.g., empty critical sections that switch quickly between
read and write phases). This can then lead to errors in how __wrphase_futex
is accessed, which in turn can lead to deadlocks.
This patch adds an option to test to add small command line option
through CMDLINE_OPTSTRING define. For instance:
#define CMDLINE_OPTSTRING "vd"
static void
cmdline_process_function (int c)
{
switch (c):
'v':
/* process '-v' option. */
break;
'd':
/* process '-d' option. */
break;
}
#define CMDLINE_PROCESS cmdline_process_function
It will add both '-v' and '-d' along with already default long options.
* support/support_test_main.c (support_test_main): Use optstring
member for option string in getopt_long.
* support/test-driver.c: Add comment about CMDLINE_OPTSTRING.
(CMDLINE_OPTSTRING): New define.
* support/test-driver.h (test_config): Add optstring member.
Current allocate_stack logic for create stacks is to first mmap all
the required memory with the desirable memory and then mprotect the
guard area with PROT_NONE if required. Although it works as expected,
it pessimizes the allocation because it requires the kernel to actually
increase commit charge (it counts against the available physical/swap
memory available for the system).
The only issue is to actually check this change since side-effects are
really Linux specific and to actually account them it would require a
kernel specific tests to parse the system wide information. On the kernel
I checked /proc/self/statm does not show any meaningful difference for
vmm and/or rss before and after thread creation. I could only see
really meaningful information checking on system wide /proc/meminfo
between thread creation: MemFree, MemAvailable, and Committed_AS shows
large difference without the patch. I think trying to use these
kind of information on a testcase is fragile.
The BZ#18988 reports shows that the commit pages are easily seen with
mlockall (MCL_FUTURE) (with lock all pages that become mapped in the
process) however a more straighfoward testcase shows that pthread_create
could be faster using this patch:
--
static const int inner_count = 256;
static const int outer_count = 128;
static
void *thread1(void *arg)
{
return NULL;
}
static
void *sleeper(void *arg)
{
pthread_t ts[inner_count];
for (int i = 0; i < inner_count; i++)
pthread_create (&ts[i], &a, thread1, NULL);
for (int i = 0; i < inner_count; i++)
pthread_join (ts[i], NULL);
return NULL;
}
int main(void)
{
pthread_attr_init(&a);
pthread_attr_setguardsize(&a, 1<<20);
pthread_attr_setstacksize(&a, 1134592);
pthread_t ts[outer_count];
for (int i = 0; i < outer_count; i++)
pthread_create(&ts[i], &a, sleeper, NULL);
for (int i = 0; i < outer_count; i++)
pthread_join(ts[i], NULL);
assert(r == 0);
}
return 0;
}
--
On x86_64 (4.4.0-45-generic, gcc 5.4.0) running the small benchtests
I see:
$ time ./test
real 0m3.647s
user 0m0.080s
sys 0m11.836s
While with the patch I see:
$ time ./test
real 0m0.696s
user 0m0.040s
sys 0m1.152s
So I added a pthread_create benchtest (thread_create) which check
the thread creation latency. As for the simple benchtests, I saw
improvements in thread creation on all architectures I tested the
change.
Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu,
arm-linux-gnueabihf, powerpc64le-linux-gnu, sparc64-linux-gnu,
and sparcv9-linux-gnu.
[BZ #18988]
* benchtests/thread_create-inputs: New file.
* benchtests/thread_create-source.c: Likewise.
* support/xpthread_attr_setguardsize.c: Likewise.
* support/Makefile (libsupport-routines): Add
xpthread_attr_setguardsize object.
* support/xthread.h: Add xpthread_attr_setguardsize prototype.
* benchtests/Makefile (bench-pthread): Add thread_create.
* nptl/allocatestack.c (allocate_stack): Call mmap with PROT_NONE and
then mprotect the required area.
Previously, the implementation would conditionally exit based on the
status argument, which GCC did not know about. This leads to
false uninitialized variable warnings when data is accessed after a
TEST_VERIFY_EXIT failure (from code which would never execute).
This is intended as a type-safe alternative to obstacks and
hand-written realloc constructs. The implementation avoids
writing function pointers to the heap.
The address family splitting via format_ai_family made unpredictable
the place where the canonname field was printed. This commit adjusts
the implementation so that the ai_flags is checked for consistency
across the list, and ai_canonname must only be present on the first
list element.
Tests for AI_CANONNAME are added to resolv/tst-resolv-basic.
Otherwise, another user might recreate these files after the first
deletion. Particularly with temporary directories, this could result
in the removal of unintended files through symbol link attacks.
This is required to remove temporary directories which contain
temporary files. Previously, FIFO order meant that directory
removal was attempted when the directory still contained files,
which meant that temporary directory cleanup was essentially
unsupported.
sys/socket.h includes sys/uio.h to get the definition of the iovec
structure.
POSIX allows sys/socket.h to make all sys/uio.h symbols visible.
However, all of sys/uio.h is XSI-shaded, so for non-XSI POSIX this
results in conformtest failures (for sys/socket.h and other headers
that include it):
Namespace violation: "UIO_MAXIOV"
Namespace violation: "readv"
Namespace violation: "writev"
Now, there is some ambiguity in POSIX about what namespace
reservations apply in this case - see
http://austingroupbugs.net/view.php?id=1127 - but glibc convention
would still avoid declaring readv and writev, for example, for feature
test macros that don't include them (if only headers from the relevant
standard are included), even if such declarations are permitted, so
there is a bug here according to glibc conventions.
This patch moves the struct iovec definition to a new
bits/types/struct_iovec.h header and includes that from sys/socket.h
instead of including the whole of sys/uio.h. This fixes the namespace
issue; however, three files in glibc that were relying on the implicit
inclusion needed to be updated to include sys/uio.h explicitly. So
there is a question of whether sys/socket.h should continue to include
sys/uio.h under some conditions, such as __USE_XOPEN or __USE_MISC or
__USE_XOPEN || __USE_MISC, for greater compatibility with code that
(wrongly) expects this optional inclusion to be present there. (I
think the three affected files in glibc should still have explicit
sys/uio.h inclusions added in any case, however.)
Tested for x86_64.
[BZ #21426]
* misc/bits/types/struct_iovec.h: New file.
* misc/Makefile (headers): Add bits/types/struct_iovec.h.
* include/bits/types/struct_iovec.h: New file.
* bits/uio.h (struct iovec): Replace by inclusion of
<bits/types/struct_iovec.h>.
* sysdeps/unix/sysv/linux/bits/uio.h (struct iovec): Likewise.
* socket/sys/socket.h: Include <bits/types/struct_iovec.h> instead
of <sys/uio.h>.
* nptl/tst-cancel4.c: Include <sys/uio.h>
* posix/test-errno.c: Likewise.
* support/resolv_test.c: Likewise.
* conform/Makefile (test-xfail-POSIX2008/arpa/inet.h/conform):
Remove.
(test-xfail-POSIX2008/netdb.h/conform): Likewise.
(test-xfail-POSIX2008/netinet/in.h/conform): Likewise.
(test-xfail-POSIX2008/sys/socket.h/conform): Likewise.
Simplify the Linux accept4 implementation based on the assumption
that it is available in some way. __ASSUME_ACCEPT4_SOCKETCALL was
previously unused, so remove it.
For ia64, the accept4 system call (and socket call) were backported
in kernel version 3.2.18. Reflect this in the installation
instructions.
* stdio-common/bug25.c: Include stdlib.h.
* support/tst-support_format_dns_packet.c: Include stdio.h,
stdlib.h, and string.h.
* support/tst-support_record_failure.c: Include string.h.
* support/tst-support_record_failure-2.sh: Adjust line number
expectations and correct a typo in an error message.
Before this change, the loop iterating over RRs in the answer
section stopped at the first CNAME record, never printing them.
The CNAME and PTR record contents was extracted from the wrong
buffer (whole packet instead RDATA). This desynced the parsing
after the first CNAME or PTR record.
Also fix the AAAA record parsing by checking their sizes.
The commit documents the ownership rules around 'struct pthread' and
when a thread can read or write to the descriptor. With those ownership
rules in place it becomes obvious that pd->stopped_start should not be
touched in several of the paths during thread startup, particularly so
for detached threads. In the case of detached threads, between the time
the thread is created by the OS kernel and the creating thread checks
pd->stopped_start, the detached thread might have already exited and the
memory for pd unmapped. As a regression test we add a simple test which
exercises this exact case by quickly creating detached threads with
large enough stacks to ensure the thread stack cache is bypassed and the
stacks are unmapped. Before the fix the testcase segfaults, after the
fix it works correctly and completes without issue.
For a detailed discussion see:
https://www.sourceware.org/ml/libc-alpha/2017-01/msg00505.html
This causes more test programs to link in the support_record_failure
function, which triggers an early call to mmap from an ELF
constructor, but this should not have side effects intefering
with the functionality actually under test (unlike, say, a call
to malloc).
The support/tst-support_record_failure-2.out test attempts to run
built code even if run-built-tests = no, so failing with
build-many-glibcs.py for all architectures whose code cannot be run on
the system running the script. This patch disables the test in that
case.
Tested for x86_64 (native), and for aarch64 with build-many-glibcs.py.
* support/Makefile (tests-special): Make definition conditional on
[$(run-built-tests) = yes].
($(objpfx)tst-support_record_failure-2.out): Make rule conditional
on [$(run-built-tests) = yes].
This patch adds a simple SYSV message queue test to check for correct
argument passing on kernel. The idea is neither to be an extensive
testing nor to check for any specific Linux test.
* sysvipc/Makefile (tests): Add test-sysvmsg.
* sysvipc/test-sysvmsg.c: New file.
* test-skeleton.c (FAIL_UNSUPPORTED): New define.
The new functions support_record_failure records a test failure,
but does not terminate the process. The macros TEST_VERIFY
and TEST_VERIFY_EXIT check that a condition is true.
The new test driver in <support/test-driver.c> has feature parity with
the old one. The main difference is that its hooking mechanism is
based on functions and function pointers instead of macros. This
commit also implements a new environment variable, TEST_COREDUMPS,
which disables the code which disables coredumps (that is, it enables
them if the invocation environment has not disabled them).
<test-skeleton.c> defines wrapper functions so that it is possible to
use existing macros with the new-style hook functionality.
This commit changes only a few test cases to the new test driver, to
make sure that it works as expected.
