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glibc/stdlib/Makefile
Florian Weimer 7a61e7f557 stdlib: Make getenv thread-safe in more cases 
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>
2024-11-21 21:10:52 +01:00

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Makefile
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# Copyright (C) 1991-2024 Free Software Foundation, Inc.
# 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/>.
#
# Makefile for stdlib routines
#
subdir := stdlib
include ../Makeconfig
headers := \
alloca.h \
bits/errno.h \
bits/indirect-return.h \
bits/monetary-ldbl.h \
bits/stdint-intn.h \
bits/stdint-least.h \
bits/stdint-uintn.h \
bits/stdlib-bsearch.h \
bits/stdlib-float.h \
bits/stdlib-ldbl.h \
bits/stdlib.h \
bits/time64.h \
bits/timesize.h \
bits/types/error_t.h \
bits/wordsize.h \
errno.h \
fmtmsg.h \
inttypes.h \
monetary.h \
stdbit.h \
stdint.h \
stdlib.h \
sys/errno.h \
sys/random.h \
sys/ucontext.h \
ucontext.h \
# headers
routines := \
a64l \
abort \
abs \
arc4random \
arc4random_uniform \
at_quick_exit \
atof \
atoi \
atol\
atoll \
bsearch \
canonicalize \
cxa_at_quick_exit \
cxa_atexit \
cxa_finalize \
cxa_thread_atexit_impl \
div \
drand48 \
drand48-iter \
drand48_r \
erand48 \
erand48_r \
exit \
fmtmsg \
getcontext \
getentropy \
getenv \
getrandom \
getsubopt \
jrand48 \
jrand48_r \
l64a \
labs \
lcong48 \
lcong48_r \
ldiv \
llabs \
lldiv \
lrand48 \
lrand48_r \
makecontext \
mblen \
mbstowcs \
mbtowc \
mrand48 \
mrand48_r \
nrand48 \
nrand48_r \
old_atexit \
on_exit atexit \
putenv \
qsort \
quick_exit \
rand \
rand_r \
random \
random_r \
rpmatch \
secure-getenv \
seed48 \
seed48_r \
setcontext \
setenv \
srand48 \
srand48_r \
stdc_bit_ceil_uc \
stdc_bit_ceil_ui \
stdc_bit_ceil_ul \
stdc_bit_ceil_ull \
stdc_bit_ceil_us \
stdc_bit_floor_uc \
stdc_bit_floor_ui \
stdc_bit_floor_ul \
stdc_bit_floor_ull \
stdc_bit_floor_us \
stdc_bit_width_uc \
stdc_bit_width_ui \
stdc_bit_width_ul \
stdc_bit_width_ull \
stdc_bit_width_us \
stdc_count_ones_uc \
stdc_count_ones_ui \
stdc_count_ones_ul \
stdc_count_ones_ull \
stdc_count_ones_us \
stdc_count_zeros_uc \
stdc_count_zeros_ui \
stdc_count_zeros_ul \
stdc_count_zeros_ull \
stdc_count_zeros_us \
stdc_first_leading_one_uc \
stdc_first_leading_one_ui \
stdc_first_leading_one_ul \
stdc_first_leading_one_ull \
stdc_first_leading_one_us \
stdc_first_leading_zero_uc \
stdc_first_leading_zero_ui \
stdc_first_leading_zero_ul \
stdc_first_leading_zero_ull \
stdc_first_leading_zero_us \
stdc_first_trailing_one_uc \
stdc_first_trailing_one_ui \
stdc_first_trailing_one_ul \
stdc_first_trailing_one_ull \
stdc_first_trailing_one_us \
stdc_first_trailing_zero_uc \
stdc_first_trailing_zero_ui \
stdc_first_trailing_zero_ul \
stdc_first_trailing_zero_ull \
stdc_first_trailing_zero_us \
stdc_has_single_bit_uc \
stdc_has_single_bit_ui \
stdc_has_single_bit_ul \
stdc_has_single_bit_ull \
stdc_has_single_bit_us \
stdc_leading_ones_uc \
stdc_leading_ones_ui \
stdc_leading_ones_ul \
stdc_leading_ones_ull \
stdc_leading_ones_us \
stdc_leading_zeros_uc \
stdc_leading_zeros_ui \
stdc_leading_zeros_ul \
stdc_leading_zeros_ull \
stdc_leading_zeros_us \
stdc_trailing_ones_uc \
stdc_trailing_ones_ui \
stdc_trailing_ones_ul \
stdc_trailing_ones_ull \
stdc_trailing_ones_us \
stdc_trailing_zeros_uc \
stdc_trailing_zeros_ui \
stdc_trailing_zeros_ul \
stdc_trailing_zeros_ull \
stdc_trailing_zeros_us \
strfmon \
strfmon_l \
strfromd \
strfromf \
strfroml \
strtod \
strtod_l \
strtod_nan \
strtof \
strtof_l \
strtof_nan \
strtol \
strtol_l \
strtold \
strtold_l \
strtold_nan \
strtoll \
strtoll_l \
strtoul \
strtoul_l \
strtoull \
strtoull_l \
swapcontext \
system \
wcstombs \
wctomb \
xpg_basename \
# routines
# Exclude fortified routines from being built with _FORTIFY_SOURCE
routines_no_fortify += \
mbstowcs \
wcstombs \
wctomb \
# routines_no_fortify
aux = \
grouping \
groupingwc \
tens_in_limb \
# aux
# These routines will be omitted from the libc shared object.
# Instead the static object files will be included in a special archive
# linked against when the shared library will be used.
static-only-routines = \
at_quick_exit \
atexit \
# static-only-routines
test-srcs := \
tst-fmtmsg \
#test-srcs
tests := \
bug-fmtmsg1 \
bug-getcontext \
bug-strtod \
bug-strtod2 \
test-a64l \
test-at_quick_exit-race \
test-atexit-race \
test-atexit-recursive \
test-bz22786 \
test-canon \
test-canon2 \
test-cxa_atexit-race \
test-cxa_atexit-race2 \
test-dlclose-exit-race \
test-on_exit-race \
testdiv \
testmb \
testmb2 \
testrand \
testsort \
tst-abs \
tst-arc4random-fork \
tst-arc4random-stats \
tst-arc4random-thread \
tst-at_quick_exit \
tst-atexit \
tst-atof1 \
tst-atof2 \
tst-bsearch \
tst-bz20544 \
tst-canon-bz26341 \
tst-concurrent-exit \
tst-concurrent-quick_exit \
tst-cxa_atexit \
tst-environ \
tst-getenv-signal \
tst-getenv-thread \
tst-getenv-unsetenv \
tst-getrandom \
tst-getrandom2 \
tst-labs \
tst-limits \
tst-llabs \
tst-makecontext \
tst-makecontext-align \
tst-makecontext2 \
tst-makecontext3 \
tst-on_exit \
tst-qsort \
tst-qsort2 \
tst-qsort3 \
tst-qsort6 \
tst-quick_exit \
tst-rand48 \
tst-rand48-2 \
tst-random \
tst-random2 \
tst-realpath \
tst-realpath-toolong \
tst-secure-getenv \
tst-setcontext \
tst-setcontext2 \
tst-setcontext3 \
tst-setcontext4 \
tst-setcontext5 \
tst-setcontext6 \
tst-setcontext7 \
tst-setcontext8 \
tst-setcontext9 \
tst-setcontext10 \
tst-setcontext11 \
tst-stdbit-Wconversion \
tst-stdbit-builtins \
tst-stdc_bit_ceil \
tst-stdc_bit_floor \
tst-stdc_bit_width \
tst-stdc_count_ones \
tst-stdc_count_zeros \
tst-stdc_first_leading_one \
tst-stdc_first_leading_zero \
tst-stdc_first_trailing_one \
tst-stdc_first_trailing_zero \
tst-stdc_has_single_bit \
tst-stdc_leading_ones \
tst-stdc_leading_zeros \
tst-stdc_trailing_ones \
tst-stdc_trailing_zeros \
tst-strfmon_l \
tst-strfrom \
tst-strfrom-locale \
tst-strtod \
tst-strtod-nan-locale \
tst-strtod-nan-sign \
tst-strtod-overflow \
tst-strtod-round \
tst-strtod-underflow \
tst-strtod2 \
tst-strtod5 \
tst-strtod6 \
tst-strtol \
tst-strtol-binary-c11 \
tst-strtol-binary-c23 \
tst-strtol-binary-gnu11 \
tst-strtol-binary-gnu23 \
tst-strtol-locale \
tst-strtoll \
tst-swapcontext1 \
tst-swapcontext2 \
tst-thread-quick_exit \
tst-tininess \
tst-unsetenv1 \
tst-width \
tst-width-stdint \
tst-xpg-basename \
# tests
tests-internal := \
tst-qsort4 \
tst-strtod1i \
tst-strtod3 \
tst-strtod4 \
tst-strtod5i \
tst-tls-atexit \
tst-tls-atexit-nodelete \
# tests-internal
tests-static := \
tst-secure-getenv \
# tests-static
tests-container := \
tst-system \
#tests-container
ifeq ($(build-hardcoded-path-in-tests),yes)
tests += \
tst-empty-env \
# tests
endif
LDLIBS-test-atexit-race = $(shared-thread-library)
LDLIBS-test-at_quick_exit-race = $(shared-thread-library)
LDLIBS-test-cxa_atexit-race = $(shared-thread-library)
LDLIBS-test-cxa_atexit-race2 = $(shared-thread-library)
LDLIBS-test-on_exit-race = $(shared-thread-library)
LDLIBS-tst-canon-bz26341 = $(shared-thread-library)
LDLIBS-tst-arc4random-fork = $(shared-thread-library)
LDLIBS-tst-arc4random-thread = $(shared-thread-library)
LDLIBS-tst-system = $(shared-thread-library)
LDLIBS-test-dlclose-exit-race = $(shared-thread-library)
LDFLAGS-test-dlclose-exit-race = $(LDFLAGS-rdynamic)
LDLIBS-test-dlclose-exit-race-helper.so = $(libsupport) $(shared-thread-library)
CFLAGS-tst-abs.c += -fno-builtin
CFLAGS-tst-labs.c += -fno-builtin
CFLAGS-tst-llabs.c += -fno-builtin
CFLAGS-tst-stdbit-Wconversion.c += -Wconversion -Werror
CFLAGS-tst-stdc_trailing_zeros.c += -fno-builtin
CFLAGS-tst-stdc_trailing_ones.c += -fno-builtin
CFLAGS-tst-stdc_leading_zeros.c += -fno-builtin
CFLAGS-tst-stdc_leading_ones.c += -fno-builtin
CFLAGS-tst-stdc_has_single_bit.c += -fno-builtin
CFLAGS-tst-stdc_first_trailing_zero.c += -fno-builtin
CFLAGS-tst-stdc_first_trailing_one.c += -fno-builtin
CFLAGS-tst-stdc_first_leading_zero.c += -fno-builtin
CFLAGS-tst-stdc_first_leading_one.c += -fno-builtin
CFLAGS-tst-stdc_count_zeros.c += -fno-builtin
CFLAGS-tst-stdc_count_ones.c += -fno-builtin
CFLAGS-tst-stdc_bit_width.c += -fno-builtin
CFLAGS-tst-stdc_bit_floor.c += -fno-builtin
CFLAGS-tst-stdc_bit_ceil.c += -fno-builtin
ifeq ($(have-cxx-thread_local),yes)
CFLAGS-tst-quick_exit.o = -std=c++11
LDLIBS-tst-quick_exit = -lstdc++
CFLAGS-tst-thread-quick_exit.o = -std=c++11
LDLIBS-tst-thread-quick_exit = -lstdc++
$(objpfx)tst-thread-quick_exit: $(shared-thread-library)
else
tests-unsupported += \
tst-quick_exit \
tst-thread-quick_exit \
# tests-unsupported
endif
modules-names = \
test-dlclose-exit-race-helper \
tst-tls-atexit-lib \
# modules-names
extra-test-objs += $(addsuffix .os, $(modules-names))
ifeq ($(build-shared),yes)
tests += \
tst-putenv \
# tests
endif
# Several mpn functions from GNU MP are used by the strtod function.
mpn-routines := \
add_n \
addmul_1 \
cmp \
divmod_1 \
divrem \
inlines \
lshift \
mod_1 \
mul \
mul_1 \
mul_n \
rshift \
sub_n \
submul_1 \
udiv_qrnnd \
# mpn-routines
mpn-headers = \
asm-syntax.h \
gmp-impl.h \
gmp-mparam.h \
gmp.h \
longlong.h \
# mpn-headers
routines := \
$(strip $(routines) $(mpn-routines)) \
dbl2mpn \
ldbl2mpn \
mpn2dbl \
mpn2flt \
mpn2ldbl \
# routines
aux += \
fpioconst \
mp_clz_tab \
# aux
tests-extras += \
tst-putenvmod \
# tests-extras
extra-test-objs += \
tst-putenvmod.os \
# extra-test-objs
generated += \
isomac \
isomac.out \
tst-putenvmod.so \
# generated
CFLAGS-bsearch.c += $(uses-callbacks)
CFLAGS-qsort.c += $(uses-callbacks)
CFLAGS-system.c += -fexceptions
CFLAGS-system.os = -fomit-frame-pointer
CFLAGS-fmtmsg.c += -fexceptions
CFLAGS-strfmon.c += $(libio-mtsafe)
CFLAGS-strfmon_l.c += $(libio-mtsafe)
# The strfrom class of functions call __printf_fp in order to convert the
# floating-point value to characters. This requires the value of IO_MTSAFE_IO.
CFLAGS-strfromd.c += $(libio-mtsafe)
CFLAGS-strfromf.c += $(libio-mtsafe)
CFLAGS-strfroml.c += $(libio-mtsafe)
CFLAGS-strtol.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtoul.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtoll.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtoull.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtof.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtof_l.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtod.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtod_l.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtold.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-strtold_l.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-secure-getenv.c += $(config-cflags-wno-ignored-attributes)
CFLAGS-tst-bsearch.c += $(stack-align-test-flags)
CFLAGS-tst-qsort.c += $(stack-align-test-flags)
CFLAGS-tst-makecontext.c += -funwind-tables
CFLAGS-tst-makecontext2.c += $(stack-align-test-flags)
CFLAGS-testmb.c += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 -Wall -Werror
# Some versions of GCC supported for building glibc do not support -std=c23
# or -std=gnu23 (added in GCC 14), or the older names -std=c2x or -std=gnu2x
# (added in GCC 9), so the tests for those versions use -std=c11 and -std=gnu11
# and then _ISOC23_SOURCE is defined in the test as needed.
CFLAGS-tst-strtol-binary-c11.c += -std=c11
CFLAGS-tst-strtol-binary-c23.c += -std=c11
CFLAGS-tst-strtol-binary-gnu11.c += -std=gnu11
CFLAGS-tst-strtol-binary-gnu23.c += -std=gnu11
# Run a test on the header files we use.
tests-special += $(objpfx)isomac.out
ifeq ($(run-built-tests),yes)
tests-special += $(objpfx)tst-fmtmsg.out
endif
include ../Rules
ifeq ($(run-built-tests),yes)
LOCALES := \
cs_CZ.UTF-8 \
de_DE.UTF-8 \
el_GR.UTF-8 \
en_US.ISO-8859-1 \
hi_IN.UTF-8 \
hr_HR.UTF-8 \
tg_TJ.UTF-8 \
tr_TR.ISO-8859-9 \
tr_TR.UTF-8 \
# LOCALES
include ../gen-locales.mk
$(objpfx)bug-strtod2.out: $(gen-locales)
$(objpfx)testmb2.out: $(gen-locales)
$(objpfx)tst-strtod.out: $(gen-locales)
$(objpfx)tst-strtod1i.out: $(gen-locales)
$(objpfx)tst-strtod3.out: $(gen-locales)
$(objpfx)tst-strtod4.out: $(gen-locales)
$(objpfx)tst-strtod5.out: $(gen-locales)
$(objpfx)tst-strtod5i.out: $(gen-locales)
$(objpfx)tst-strtol-locale.out: $(gen-locales)
$(objpfx)tst-strtod-nan-locale.out: $(gen-locales)
$(objpfx)tst-strfmon_l.out: $(gen-locales)
$(objpfx)tst-strfrom.out: $(gen-locales)
$(objpfx)tst-strfrom-locale.out: $(gen-locales)
$(objpfx)test-dlclose-exit-race.out: $(objpfx)test-dlclose-exit-race-helper.so
endif
# Testdir has to be named stdlib and needs to be writable
test-canon-ARGS = --test-dir=${common-objpfx}stdlib
bug-fmtmsg1-ENV = SEV_LEVEL=foo,11,newsev
$(objpfx)isomac.out: $(objpfx)isomac
$(dir $<)$(notdir $<) '$(CC)' \
'-I../include $(+sysdep-includes) $(sysincludes) -I..' > $@; \
$(evaluate-test)
isomac-CFLAGS = -O
$(objpfx)isomac: isomac.c
$(native-compile)
$(objpfx)tst-fmtmsg.out: tst-fmtmsg.sh $(objpfx)tst-fmtmsg
$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
'$(run-program-env)' '$(test-program-prefix-after-env)' \
$(common-objpfx)stdlib/; \
$(evaluate-test)
$(objpfx)tst-putenv: $(objpfx)tst-putenvmod.so
LDFLAGS-tst-putenv = -Wl,--no-as-needed
$(objpfx)tst-putenvmod.so: $(objpfx)tst-putenvmod.os $(link-libc-deps)
$(build-module)
libof-tst-putenvmod = extramodules
$(objpfx)bug-getcontext: $(libm)
$(objpfx)bug-strtod2: $(libm)
$(objpfx)tst-strtod-round: $(libm)
$(objpfx)tst-tininess: $(libm)
$(objpfx)tst-strtod-underflow: $(libm)
$(objpfx)tst-strtod6: $(libm)
$(objpfx)tst-strtod-nan-locale: $(libm)
$(objpfx)tst-strtod-nan-sign: $(libm)
tst-tls-atexit-lib.so-no-z-defs = yes
test-dlclose-exit-race-helper.so-no-z-defs = yes
$(objpfx)tst-tls-atexit: $(shared-thread-library)
$(objpfx)tst-tls-atexit.out: $(objpfx)tst-tls-atexit-lib.so
$(objpfx)tst-tls-atexit-nodelete: $(shared-thread-library)
$(objpfx)tst-tls-atexit-nodelete.out: $(objpfx)tst-tls-atexit-lib.so
$(objpfx)tst-setcontext3.out: tst-setcontext3.sh $(objpfx)tst-setcontext3
$(SHELL) $< $(common-objpfx) '$(test-program-prefix-before-env)' \
'$(run-program-env)' '$(test-program-prefix-after-env)' \
$(common-objpfx)stdlib/; \
$(evaluate-test)
$(objpfx)tst-qsort5: $(libm)
$(objpfx)tst-concurrent-exit: $(shared-thread-library)
$(objpfx)tst-concurrent-quick_exit: $(shared-thread-library)
$(objpfx)tst-getrandom2: $(shared-thread-library)
$(objpfx)tst-getenv-signal: $(shared-thread-library)
$(objpfx)tst-getenv-thread: $(shared-thread-library)
$(objpfx)tst-getenv-unsetenv: $(shared-thread-library)
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