Async-signal-safety is preserved, too. In fact, getenv is fully
reentrant and can be called from the malloc call in setenv
(if a replacement malloc uses getenv during its initialization).
This is relatively easy to implement because even before this change,
setenv, unsetenv, clearenv, putenv do not deallocate the environment
strings themselves as they are removed from the environment.
The main changes are:
* Use release stores for environment array updates, following
the usual pattern for safely publishing immutable data
(in this case, the environment strings).
* Do not deallocate the environment array. Instead, keep older
versions around and adopt an exponential resizing policy. This
results in an amortized constant space leak per active environment
variable, but there already is such a leak for the variable itself
(and that is even length-dependent, and includes no-longer used
values).
* Add a seqlock-like mechanism to retry getenv if a concurrent
unsetenv is observed. Without that, it is possible that
getenv returns NULL for a variable that is never unset. This
is visible on some AArch64 implementations with the newly
added stdlib/tst-getenv-unsetenv test case. The mechanism
is not a pure seqlock because it tolerates one write from
unsetenv. This avoids the need for a second copy of the
environ array that getenv can read from a signal handler
that happens to interrupt an unsetenv call.
No manual updates are included with this patch because environ
usage with execve, posix_spawn, system is still not thread-safe
relative unsetenv. The new process may end up with an environment
that misses entries that were never unset. This is the same issue
described above for getenv.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.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
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).
NULL, "" or contains '=' character in it. Reported by
Michael T Kerrisk <mtk-lists@gmx.net>.
* stdlib/tst-environ.c: Include errno.h.
(main): Add tests for these arguments to setenv/unsetenv.
2001-07-06 Paul Eggert <eggert@twinsun.com>
* manual/argp.texi: Remove ignored LGPL copyright notice; it's
not appropriate for documentation anyway.
* manual/libc-texinfo.sh: "Library General Public License" ->
"Lesser General Public License".
2001-07-06 Andreas Jaeger <aj@suse.de>
* All files under GPL/LGPL version 2: Place under LGPL version
2.1.
1999-10-12 Andreas Jaeger <aj@suse.de>
* stdlib/tst-environ.c: Include <string.h> for strcpy declaration.
* math/basic-test.c: Fix typo.
* locale/programs/xstrdup.c: Include string.h for glibc
compilation to get string prototypes.
* sysdeps/unix/sysv/linux/alpha/sys/ucontext.h: Add definition of
gregset_t and fpregset_t.
* sysdeps/generic/s_nexttowardf.c: Add parenthesis to shut up gcc
warnings. Correct value for x == 0.
* argp/argp-help.c: Remove broken definition of flockfile and
funlockfile.
1999-10-12 Andreas Schwab <schwab@suse.de>
* sysdeps/unix/sysv/linux/alpha/bits/sigaction.h: Update to match
generic Linux version.
1999-10-12 Ulrich Drepper <drepper@cygnus.com>
* sysdeps/unix/sysv/linux/bits/sigaction.h: Remove K&R compatibility.
1999-09-19 Ulrich Drepper <drepper@cygnus.com>
* po/pl.po: Updated.
1999-09-17 Andreas Schwab <schwab@suse.de>
* Makefile (clean): Also remove $(postclean) files.
1999-09-15 Andreas Jaeger <aj@suse.de>
* pwd/Makefile (otherlibs): Add for building with static-nss.
* inet/Makefile (otherlibs): Likewise.
1999-09-15 Andreas Jaeger <aj@suse.de>
* sysdeps/generic/aio_sigqueue.c (__aio_sigqueue): Use old style
function definition to avoid a compilation failure.
1999-09-15 Andreas Jaeger <aj@suse.de>
* stdlib/tst-environ.c (main): Add getenv regression test for
environment variable that's one character long.
1999-09-15 Andreas Jaeger <aj@suse.de>
* sysdeps/unix/sysv/linux/i386/sigaction.c: Protect real time
signal definitions to let glibc compile with older Linux versions
(2.0.10 to 2.1.100 or so).
