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a643f60c53
In _FORTIFY_SOURCE=3, the size expression may be non-constant, resulting in branches in the inline functions remaining intact and causing a tiny overhead. Clang (and in future, gcc) make sure that the -1 case is always safe, i.e. any comparison of the generated expression with (size_t)-1 is always false so that bit is taken care of. The rest is avoidable since we want the _chk variant whenever we have a size expression and it's not -1. Rework the conditionals in a uniform way to clearly indicate two conditions at compile time: - Either the size is unknown (-1) or we know at compile time that the operation length is less than the object size. We can call the original function in this case. It could be that either the length, object size or both are non-constant, but the compiler, through range analysis, is able to fold the *comparison* to a constant. - The size and length are known and the compiler can see at compile time that operation length > object size. This is valid grounds for a warning at compile time, followed by emitting the _chk variant. For everything else, emit the _chk variant. This simplifies most of the fortified function implementations and at the same time, ensures that only one call from _chk or the regular function is emitted. Signed-off-by: Siddhesh Poyarekar <siddhesh@sourceware.org> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
71 lines
2.6 KiB
C
71 lines
2.6 KiB
C
/* Checking macros for poll functions.
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Copyright (C) 2012-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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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
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<https://www.gnu.org/licenses/>. */
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#ifndef _SYS_POLL_H
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# error "Never include <bits/poll2.h> directly; use <sys/poll.h> instead."
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#endif
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__BEGIN_DECLS
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extern int __REDIRECT (__poll_alias, (struct pollfd *__fds, nfds_t __nfds,
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int __timeout), poll);
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extern int __poll_chk (struct pollfd *__fds, nfds_t __nfds, int __timeout,
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__SIZE_TYPE__ __fdslen)
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__attr_access ((__write_only__, 1, 2));
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extern int __REDIRECT (__poll_chk_warn, (struct pollfd *__fds, nfds_t __nfds,
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int __timeout, __SIZE_TYPE__ __fdslen),
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__poll_chk)
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__warnattr ("poll called with fds buffer too small file nfds entries");
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__fortify_function __fortified_attr_access (__write_only__, 1, 2) int
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poll (struct pollfd *__fds, nfds_t __nfds, int __timeout)
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{
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return __glibc_fortify (poll, __nfds, sizeof (*__fds),
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__glibc_objsize (__fds),
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__fds, __nfds, __timeout);
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}
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#ifdef __USE_GNU
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extern int __REDIRECT (__ppoll_alias, (struct pollfd *__fds, nfds_t __nfds,
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const struct timespec *__timeout,
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const __sigset_t *__ss), ppoll);
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extern int __ppoll_chk (struct pollfd *__fds, nfds_t __nfds,
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const struct timespec *__timeout,
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const __sigset_t *__ss, __SIZE_TYPE__ __fdslen)
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__attr_access ((__write_only__, 1, 2));
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extern int __REDIRECT (__ppoll_chk_warn, (struct pollfd *__fds, nfds_t __nfds,
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const struct timespec *__timeout,
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const __sigset_t *__ss,
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__SIZE_TYPE__ __fdslen),
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__ppoll_chk)
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__warnattr ("ppoll called with fds buffer too small file nfds entries");
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__fortify_function __fortified_attr_access (__write_only__, 1, 2) int
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ppoll (struct pollfd *__fds, nfds_t __nfds, const struct timespec *__timeout,
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const __sigset_t *__ss)
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{
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return __glibc_fortify (ppoll, __nfds, sizeof (*__fds),
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__glibc_objsize (__fds),
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__fds, __nfds, __timeout, __ss);
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}
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#endif
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__END_DECLS
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