glibc/sysdeps/unix/sysv/linux/open.c

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Avoid cancellable I/O primitives in ld.so. Neither the <dlfcn.h> entry points, nor lazy symbol resolution, nor initial shared library load-up, are cancellation points, so ld.so should exclusively use I/O primitives that are not cancellable. We currently achieve this by having the cancellation hooks compile as no-ops when IS_IN(rtld); this patch changes to using exclusively _nocancel primitives in the source code instead, which makes the intent clearer and significantly reduces the amount of code compiled under IS_IN(rtld) as well as IS_IN(libc) -- in particular, elf/Makefile no longer thinks we require a copy of unwind.c in rtld-libc.a. (The older mechanism is preserved as a backstop.) The bulk of the change is splitting up the files that define the _nocancel I/O functions, so they don't also define the variants that *are* cancellation points; after which, the existing logic for picking out the bits of libc that need to be recompiled as part of ld.so Just Works. I did this for all of the _nocancel functions, not just the ones used by ld.so, for consistency. fcntl was a little tricky because it's only a cancellation point for certain opcodes (F_SETLKW(64), which can block), and the existing __fcntl_nocancel wasn't applying the FCNTL_ADJUST_CMD hook, which strikes me as asking for trouble, especially as the only nontrivial definition of FCNTL_ADJUST_CMD (for powerpc64) changes F_*LK* opcodes. To fix this, fcntl_common moves to fcntl_nocancel.c along with __fcntl_nocancel, and changes its name to the extern (but hidden) symbol __fcntl_nocancel_adjusted, so that regular fcntl can continue calling it. __fcntl_nocancel now applies FCNTL_ADJUST_CMD; so that both both fcntl.c and fcntl_nocancel.c can see it, the only nontrivial definition moves from sysdeps/u/s/l/powerpc/powerpc64/fcntl.c to .../powerpc64/sysdep.h and becomes entirely a macro, instead of a macro that calls an inline function. The nptl version of libpthread also changes a little, because its "compat-routines" formerly included files that defined all the _nocancel functions it uses; instead of continuing to duplicate them, I exported the relevant ones from libc.so as GLIBC_PRIVATE. Since the Linux fcntl.c calls a function defined by fcntl_nocancel.c, it can no longer be used from libpthread.so; instead, introduce a custom forwarder, pt-fcntl.c, and export __libc_fcntl from libc.so as GLIBC_PRIVATE. The nios2-linux ABI doesn't include a copy of vfork() in libpthread, and it was handling that by manipulating libpthread-routines in .../linux/nios2/Makefile; it is cleaner to do what other such ports do, and have a pt-vfork.S that defines no symbols. Right now, it appears that Hurd does not implement _nocancel I/O, so sysdeps/generic/not-cancel.h will forward everything back to the regular functions. This changed the names of some of the functions that sysdeps/mach/hurd/dl-sysdep.c needs to interpose. * elf/dl-load.c, elf/dl-misc.c, elf/dl-profile.c, elf/rtld.c * sysdeps/unix/sysv/linux/dl-sysdep.c Include not-cancel.h. Use __close_nocancel instead of __close, __open64_nocancel instead of __open, __read_nocancel instead of __libc_read, and __write_nocancel instead of __libc_write. * csu/check_fds.c (check_one_fd) * sysdeps/posix/fdopendir.c (__fdopendir) * sysdeps/posix/opendir.c (__alloc_dir): Use __fcntl_nocancel instead of __fcntl and/or __libc_fcntl. * sysdeps/unix/sysv/linux/pthread_setname.c (pthread_setname_np) * sysdeps/unix/sysv/linux/pthread_getname.c (pthread_getname_np) * sysdeps/unix/sysv/linux/i386/smp.h (is_smp_system): Use __open64_nocancel instead of __open_nocancel. * sysdeps/unix/sysv/linux/not-cancel.h: Move all of the hidden_proto declarations to the end and issue them if either IS_IN(libc) or IS_IN(rtld). * sysdeps/unix/sysv/linux/Makefile [subdir=io] (sysdep_routines): Add close_nocancel, fcntl_nocancel, nanosleep_nocancel, open_nocancel, open64_nocancel, openat_nocancel, pause_nocancel, read_nocancel, waitpid_nocancel, write_nocancel. * io/Versions [GLIBC_PRIVATE]: Add __libc_fcntl, __fcntl_nocancel, __open64_nocancel, __write_nocancel. * posix/Versions: Add __nanosleep_nocancel, __pause_nocancel. * nptl/pt-fcntl.c: New file. * nptl/Makefile (pthread-compat-wrappers): Remove fcntl. (libpthread-routines): Add pt-fcntl. * include/fcntl.h (__fcntl_nocancel_adjusted): New function. (__libc_fcntl): Remove attribute_hidden. * sysdeps/unix/sysv/linux/fcntl.c (__libc_fcntl): Call __fcntl_nocancel_adjusted, not fcntl_common. (__fcntl_nocancel): Move to new file fcntl_nocancel.c. (fcntl_common): Rename to __fcntl_nocancel_adjusted; also move to fcntl_nocancel.c. * sysdeps/unix/sysv/linux/fcntl_nocancel.c: New file. * sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c: Remove file. * sysdeps/unix/sysv/linux/powerpc/powerpc64/sysdep.h: Define FCNTL_ADJUST_CMD here, as a self-contained macro. * sysdeps/unix/sysv/linux/close.c: Move __close_nocancel to... * sysdeps/unix/sysv/linux/close_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/nanosleep.c: Move __nanosleep_nocancel to... * sysdeps/unix/sysv/linux/nanosleep_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/open.c: Move __open_nocancel to... * sysdeps/unix/sysv/linux/open_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/open64.c: Move __open64_nocancel to... * sysdeps/unix/sysv/linux/open64_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/openat.c: Move __openat_nocancel to... * sysdeps/unix/sysv/linux/openat_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/openat64.c: Move __openat64_nocancel to... * sysdeps/unix/sysv/linux/openat64_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/pause.c: Move __pause_nocancel to... * sysdeps/unix/sysv/linux/pause_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/read.c: Move __read_nocancel to... * sysdeps/unix/sysv/linux/read_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/waitpid.c: Move __waitpid_nocancel to... * sysdeps/unix/sysv/linux/waitpid_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/write.c: Move __write_nocancel to... * sysdeps/unix/sysv/linux/write_nocancel.c: ...this new file. * sysdeps/unix/sysv/linux/nios2/Makefile: Don't override libpthread-routines. * sysdeps/unix/sysv/linux/nios2/pt-vfork.S: New file which defines nothing. * sysdeps/mach/hurd/dl-sysdep.c: Define __read instead of __libc_read, and __write instead of __libc_write. Define __open64 in addition to __open.
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/* Linux open syscall implementation, non-LFS.
Copyright (C) 2017-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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
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License along with the GNU C Library. If not, see
Prefer https to http for gnu.org and fsf.org URLs Also, change sources.redhat.com to sourceware.org. This patch was automatically generated by running the following shell script, which uses GNU sed, and which avoids modifying files imported from upstream: sed -ri ' s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g ' \ $(find $(git ls-files) -prune -type f \ ! -name '*.po' \ ! -name 'ChangeLog*' \ ! -path COPYING ! -path COPYING.LIB \ ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \ ! -path manual/texinfo.tex ! -path scripts/config.guess \ ! -path scripts/config.sub ! -path scripts/install-sh \ ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \ ! -path INSTALL ! -path locale/programs/charmap-kw.h \ ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \ ! '(' -name configure \ -execdir test -f configure.ac -o -f configure.in ';' ')' \ ! '(' -name preconfigure \ -execdir test -f preconfigure.ac ';' ')' \ -print) and then by running 'make dist-prepare' to regenerate files built from the altered files, and then executing the following to cleanup: chmod a+x sysdeps/unix/sysv/linux/riscv/configure # Omit irrelevant whitespace and comment-only changes, # perhaps from a slightly-different Autoconf version. git checkout -f \ sysdeps/csky/configure \ sysdeps/hppa/configure \ sysdeps/riscv/configure \ sysdeps/unix/sysv/linux/csky/configure # Omit changes that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines git checkout -f \ sysdeps/powerpc/powerpc64/ppc-mcount.S \ sysdeps/unix/sysv/linux/s390/s390-64/syscall.S # Omit change that caused a pre-commit check to fail like this: # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
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<https://www.gnu.org/licenses/>. */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdarg.h>
#include <sysdep-cancel.h>
#ifndef __OFF_T_MATCHES_OFF64_T
linux: open and openat ignore 'mode' with O_TMPFILE in flags Both open and openat load their last argument 'mode' lazily, using va_arg() only if O_CREAT is found in oflag. This is wrong, mode is also necessary if O_TMPFILE is in oflag. By chance on x86_64, the problem wasn't evident when using O_TMPFILE with open, as the 3rd argument of open, even when not loaded with va_arg, is left untouched in RDX, where the syscall expects it. However, openat was not so lucky, and O_TMPFILE couldn't be used: mode is the 4th argument, in RCX, but the syscall expects its 4th argument in a different register than the glibc wrapper, in R10. Introduce a macro __OPEN_NEEDS_MODE (oflag) to test if either O_CREAT or O_TMPFILE is set in oflag. Tested on Linux x86_64. [BZ #17523] * io/fcntl.h (__OPEN_NEEDS_MODE): New macro. * io/bits/fcntl2.h (open): Use it. (openat): Likewise. * io/open.c (__libc_open): Likewise. * io/open64.c (__libc_open64): Likewise. * io/open64_2.c (__open64_2): Likewise. * io/open_2.c (__open_2): Likewise. * io/openat.c (__openat): Likewise. * io/openat64.c (__openat64): Likewise. * io/openat64_2.c (__openat64_2): Likewise. * io/openat_2.c (__openat_2): Likewise. * sysdeps/mach/hurd/open.c (__libc_open): Likewise. * sysdeps/mach/hurd/openat.c (__openat): Likewise. * sysdeps/posix/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/dl-openat64.c (openat64): Likewise. * sysdeps/unix/sysv/linux/generic/open.c (__libc_open): Likewise. (__open_nocancel): Likewise. * sysdeps/unix/sysv/linux/generic/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/openat.c (__OPENAT): Likewise.
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/* Open FILE with access OFLAG. If O_CREAT or O_TMPFILE is in OFLAG,
a third argument is the file protection. */
int
__libc_open (const char *file, int oflag, ...)
{
int mode = 0;
linux: open and openat ignore 'mode' with O_TMPFILE in flags Both open and openat load their last argument 'mode' lazily, using va_arg() only if O_CREAT is found in oflag. This is wrong, mode is also necessary if O_TMPFILE is in oflag. By chance on x86_64, the problem wasn't evident when using O_TMPFILE with open, as the 3rd argument of open, even when not loaded with va_arg, is left untouched in RDX, where the syscall expects it. However, openat was not so lucky, and O_TMPFILE couldn't be used: mode is the 4th argument, in RCX, but the syscall expects its 4th argument in a different register than the glibc wrapper, in R10. Introduce a macro __OPEN_NEEDS_MODE (oflag) to test if either O_CREAT or O_TMPFILE is set in oflag. Tested on Linux x86_64. [BZ #17523] * io/fcntl.h (__OPEN_NEEDS_MODE): New macro. * io/bits/fcntl2.h (open): Use it. (openat): Likewise. * io/open.c (__libc_open): Likewise. * io/open64.c (__libc_open64): Likewise. * io/open64_2.c (__open64_2): Likewise. * io/open_2.c (__open_2): Likewise. * io/openat.c (__openat): Likewise. * io/openat64.c (__openat64): Likewise. * io/openat64_2.c (__openat64_2): Likewise. * io/openat_2.c (__openat_2): Likewise. * sysdeps/mach/hurd/open.c (__libc_open): Likewise. * sysdeps/mach/hurd/openat.c (__openat): Likewise. * sysdeps/posix/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/dl-openat64.c (openat64): Likewise. * sysdeps/unix/sysv/linux/generic/open.c (__libc_open): Likewise. (__open_nocancel): Likewise. * sysdeps/unix/sysv/linux/generic/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/openat.c (__OPENAT): Likewise.
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if (__OPEN_NEEDS_MODE (oflag))
{
va_list arg;
va_start (arg, oflag);
mode = va_arg (arg, int);
va_end (arg);
}
nptl: Rewrite cancellation macros This patch changes the way cancellation entrypoints are defined to instead call the macro SYSCALL_CANCEL. An usual cnacellation definition is defined as: if (SINGLE_THREAD_P) return INLINE_SYSCALL (syscall, NARGS, args...) int oldtype = LIBC_CANCEL_ASYNC (); return INLINE_SYSCALL (syscall, NARGS, args...) LIBC_CANCEL_RESET (oldtype); And it is rewrited as just: SYSCALL_CANCEL (syscall, args...) The idea is to remove LIBC_CANCEL_ASYNC/LIBC_CANCEL_RESET explicit usage. Tested on i386, x86_64, powerpc32, powerpc64le, arm, and aarch64. * sysdeps/unix/sysdep.h [SYSCALL_CANCEL]: New macro: define cancellable syscalls. (SYS_ify): Add guard to no redefine it. (INLINE_SYSCALL): Likewise. * sysdeps/unix/sysv/linux/accept4.c (accept4): Remove LIBC_CANCEL_ASYNC/INLINE_SYSCALL/LIBC_CANCEL_RESET and use SYSCALL_CANCEL instead. * sysdeps/unix/sysv/linux/alpha/fdatasync.c (__fdatasync): Likewise. * sysdeps/unix/sysv/linux/arm/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/arm/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/arm/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/arm/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/unix/sysv/linux/epoll_pwait.c (epoll_pwait): Likewise. * sysdeps/unix/sysv/linux/fallocate.c (fallocate): Likewise. * sysdeps/unix/sysv/linux/fallocate64.c (fallocate64): Likewise. * sysdeps/unix/sysv/linux/generic/open.c (__libc_open): Likewise. * sysdeps/unix/sysv/linux/generic/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/generic/pause.c (__libc_pause): Likewise. * sysdeps/unix/sysv/linux/generic/poll.c (__poll): Likewise. * sysdeps/unix/sysv/linux/generic/recv.c (__libc_recv): Likewise. * sysdeps/unix/sysv/linux/generic/select.c (__select): Likewise. * sysdeps/unix/sysv/linux/generic/send.c (__libc_send): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/preadv.c (__libc_preadv): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/preadv64.c (__libc_readv64): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/unix/sysv/linux/generic/wordsize-32/pwritev.c (__libc_pwritev): Likewise. * sysdeps/sysv/linux/generic/wordsize-32/pwritev64.c (__libc_pwritev64): Likewise. * sysdeps/unix/sysv/linux/i386/fcntl.c (__libc_fcntl): Likewise. * sysdeps/unix/sysv/linux/mips/mips32/sync_file_range.c (sync_file_range): Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n32/fallocate.c (fallocate): Likewise. * sysdeps/unix/sysv/linux/mips/mips64/n32/fallocate64.c (fallocate64): Likewise. * sysdeps/unix/sysv/linux/mips/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/mips/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/mips/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/mips/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/unix/sysv/linux/msgrcv.c (__libc_msgrcv): Likewise. * sysdeps/unix/sysv/linux/msgsnd.c (__libc_msgsnd): Likewise. * sysdeps/unix/sysv/linux/open64.c (__libc_open64): Likewise. * sysdeps/unix/sysv/linux/openat.c (__libc_openat): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/pread64.c (__libc_read64): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/pwrite.c (__libc_write): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc32/pwrite64.c (__libc_write64): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/fcntl.c (__libc_fcntl): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/powerpc/powerpc64/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/sysv/linux/powerpc/powerpc64/sync_file_range.c (sync_file_range): Likewise. * sysdeps/unix/sysv/linux/ppoll.c (ppoll): Likewise. * sysdeps/unix/sysv/linux/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/preadv.c (__libc_preadv): Likewise. * sysdeps/unix/sysv/linux/pselect.c (__pselect): Likewise. * sysdeps/unix/sysv/linux/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/unix/sysv/linux/pwritev.c (PWRITEV): Likewise. * sysdeps/unix/sysv/linux/readv.c (__libc_readv): Likewise. * sysdeps/unix/sysv/linux/recvmmsg.c (recvmmsg): Likewise. * sysdeps/unix/sysv/linux/sendmmsg.c (sendmmsg): Likewise. * sysdeps/unix/sysv/linux/sh/pread.c (__libc_pread): Likewise. * sysdeps/unix/sysv/linux/sh/pread64.c (__libc_pread64): Likewise. * sysdeps/unix/sysv/linux/sh/pwrite.c (__libc_pwrite): Likewise. * sysdeps/unix/sysv/linux/sh/pwrite64.c (__libc_pwrite64): Likewise. * sysdeps/unix/sysv/linux/sigsuspend.c (__sigsuspend): Likewise. * sysdeps/unix/sysv/linux/sigtimedwait.c (__sigtimedwait): Likewise. * sysdeps/unix/sysv/linux/sigwaitinfo.c (__sigwaitinfo): Likewise. * sysdeps/unix/sysv/linux/sparc/sparc64/msgrcv.c (__libc_msgrcv): Likewise. * sysdeps/unix/sysv/linux/sync_file_range.c (sync_file_range): Likewise. * sysdeps/unix/sysv/linux/tcdrain.c (__libc_tcdrain): Likewise. * sysdeps/unix/sysv/linux/timer_routines.c (timer_helper_thread): Likewise. * sysdeps/unix/sysv/linux/wait.c (__libc_wait): Likewise. * sysdeps/unix/sysv/linux/waitid.c (__waitid): Likewise. * sysdeps/unix/sysv/linux/waitpid.c (__libc_waitpid): Likewise. * sysdeps/unix/sysv/linux/wordsize-64/fallocate.c (fallocate): Likewise. * sysdeps/unix/sysv/linux/wordsize-64/preadv.c (preadv): Likewise. * sysdeps/unix/sysv/linux/wordsize-64/pwritev.c (pwritev): Likewise. * sysdeps/unix/sysv/linux/writev.c (__libc_writev): Likewise. * sysdeps/unix/sysv/linux/x86_64/recv.c (__libc_recv): Likewise. * sysdeps/unix/sysv/linux/x86_64/send.c (__libc_send): Likewise.
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return SYSCALL_CANCEL (openat, AT_FDCWD, file, oflag, mode);
}
libc_hidden_def (__libc_open)
weak_alias (__libc_open, __open)
libc_hidden_weak (__open)
weak_alias (__libc_open, open)
#endif