If there is enough space in the chunk to satisfy the new size, return
the old pointer as is, thus avoiding any locks or reallocations. The
only real place this has a benefit is in large chunks that tend to get
satisfied with mmap, since there is a large enough spare size (up to a
page) for it to matter. For allocations on heap, the extra size is
typically barely a few bytes (up to 15) and it's unlikely that it would
make much difference in performance.
Also added a smoke test to ensure that the old pointer is returned
unchanged if the new size to realloc is within usable size of the old
pointer.
Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
Reviewed-by: DJ Delorie <dj@redhat.com>
This addresses more (correct) use-after-free warnings reported by
GCC 12 on some targets.
Fixes commit c094c232eb ("Avoid
-Wuse-after-free in tests [BZ #26779].").
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
POSIX explicitly says that applications should check errno only after
failure, so the errno value can be clobbered on success as long as it
is not set to zero.
Changelog:
[BZ #22611]
* malloc/tst-realloc.c (do_test): Remove the test checking that errno
is unchanged on success.
Quite a few tests include libc-internal.h just for the DIAG_* macros.
Split those macros to their own file, which can be included safely in
_ISOMAC mode. I also moved ignore_value, since it seems logically
related, even though I didn't notice any tests needing it.
Also add -Wnonnull suppressions to two tests that _should_ have them,
but the error is masked when compiling against internal headers.
* include/libc-diag.h: New file. Define ignore_value,
DIAG_PUSH_NEEDS_COMMENT, DIAG_POP_NEEDS_COMMENT,
DIAG_IGNORE_NEEDS_COMMENT, and DIAG_IGNORE_Os_NEEDS_COMMENT here.
* include/libc-internal.h: Definitions of above macros moved from
here. Include libc-diag.h. Add copyright notice.
* malloc/tst-malloc.c, malloc/tst-memcheck.c, malloc/tst-realloc.c
* misc/tst-error1.c, posix/tst-dir.c, stdio-common/bug21.c
* stdio-common/scanf14.c, stdio-common/scanf4.c, stdio-common/scanf7.c
* stdio-common/test-vfprintf.c, stdio-common/tst-printf.c
* stdio-common/tst-printfsz.c, stdio-common/tst-sprintf.c
* stdio-common/tst-unlockedio.c, stdio-common/tstdiomisc.c
* stdlib/bug-getcontext.c, string/tester.c, string/tst-endian.c
* time/tst-strptime2.c, wcsmbs/tst-wcstof.c:
Include libc-diag.h instead of libc-internal.h.
* stdlib/tst-environ.c: Include libc-diag.h. Suppress -Wnonnull for
call to unsetenv (NULL).
* nptl/tst-mutex1.c: Include libc-diag.h. Suppress -Wnonnull for
call to pthread_mutexattr_destroy (NULL).
GCC 7 has a -Walloc-size-larger-than= warning for allocations of half
the address space or more. This causes errors building glibc tests
that deliberately test failure of very large allocations. This patch
arranges for this warning to be ignored around the problematic
function calls.
Tested compilation for aarch64 (GCC mainline) with
build-many-glibcs.py; did execution testing for x86_64 (GCC 5).
* malloc/tst-malloc.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
malloc with negative sizes.
* malloc/tst-mcheck.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
malloc and realloc with negative sizes.
* malloc/tst-realloc.c: Include <libc-internal.h>.
(do_test): Disable -Walloc-size-larger-than= around tests of
realloc with negative sizes.
The current tests don't test the functionality of realloc in detail.
Add a new test for realloc that exercises some of the corner cases
that are not otherwise tested.
ChangeLog:
2013-09-09 Will Newton <will.newton@linaro.org>
* malloc/Makefile: Add tst-realloc to tests.
* malloc/tst-realloc.c: New file.
