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4c3df0eba5
For !__ASSUME_TIME64_SYSCALLS there is no need to issue a 64-bit syscall if the provided timeout fits in a 32-bit one. The 64-bit usage should be rare since the timeout is a relative one. This also avoids the need to use supports_time64() (which breaks the usage case of live migration like CRIU or similar). It also fixes an issue on 32-bit select call for !__ASSUME_PSELECT (microblase with older kernels only) where the expected timeout is a 'struct timeval' instead of 'struct timespec'. Checked on i686-linux-gnu on a 4.15 kernel and on a 5.11 kernel (with and without --enable-kernel=5.1) and on x86_64-linux-gnu. Reviewed-by: Lukasz Majewski <lukma@denx.de>
143 lines
4.0 KiB
C
143 lines
4.0 KiB
C
/* Linux select implementation.
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Copyright (C) 2017-2021 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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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/select.h>
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#include <errno.h>
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#include <sysdep-cancel.h>
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/* Check the first NFDS descriptors each in READFDS (if not NULL) for read
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readiness, in WRITEFDS (if not NULL) for write readiness, and in EXCEPTFDS
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(if not NULL) for exceptional conditions. If TIMEOUT is not NULL, time out
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after waiting the interval specified therein. Returns the number of ready
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descriptors, or -1 for errors. */
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int
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__select64 (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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struct __timeval64 *timeout)
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{
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__time64_t s = timeout != NULL ? timeout->tv_sec : 0;
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int32_t us = timeout != NULL ? timeout->tv_usec : 0;
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int32_t ns;
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if (s < 0 || us < 0)
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return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
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/* Normalize the timeout, as legacy Linux __NR_select and __NR__newselect.
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Different than syscall, it also handle possible overflow. */
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if (us / USEC_PER_SEC > INT64_MAX - s)
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{
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s = INT64_MAX;
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ns = NSEC_PER_SEC - 1;
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}
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else
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{
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s += us / USEC_PER_SEC;
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us = us % USEC_PER_SEC;
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ns = us * NSEC_PER_USEC;
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}
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struct __timespec64 ts64, *pts64 = NULL;
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if (timeout != NULL)
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{
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ts64.tv_sec = s;
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ts64.tv_nsec = ns;
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pts64 = &ts64;
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}
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#ifndef __NR_pselect6_time64
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# define __NR_pselect6_time64 __NR_pselect6
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#endif
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#ifdef __ASSUME_TIME64_SYSCALLS
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int r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds, exceptfds,
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pts64, NULL);
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if (timeout != NULL)
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TIMESPEC_TO_TIMEVAL (timeout, pts64);
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return r;
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#else
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bool need_time64 = timeout != NULL && !in_time_t_range (timeout->tv_sec);
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if (need_time64)
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{
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int r = SYSCALL_CANCEL (pselect6_time64, nfds, readfds, writefds,
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exceptfds, pts64, NULL);
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if ((r >= 0 || errno != ENOSYS) && timeout != NULL)
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{
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TIMESPEC_TO_TIMEVAL (timeout, &ts64);
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}
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else
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__set_errno (EOVERFLOW);
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return r;
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}
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# ifdef __ASSUME_PSELECT
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struct timespec ts32, *pts32 = NULL;
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if (pts64 != NULL)
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{
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ts32.tv_sec = pts64->tv_sec;
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ts32.tv_nsec = pts64->tv_nsec;
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pts32 = &ts32;
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}
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int r = SYSCALL_CANCEL (pselect6, nfds, readfds, writefds, exceptfds, pts32,
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NULL);
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if (timeout != NULL)
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TIMESPEC_TO_TIMEVAL (timeout, pts32);
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return r;
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# else
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struct timeval tv32, *ptv32 = NULL;
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if (pts64 != NULL)
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{
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tv32 = valid_timespec64_to_timeval (*pts64);
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ptv32 = &tv32;
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}
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int r = SYSCALL_CANCEL (select, nfds, readfds, writefds, exceptfds, ptv32);
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if (timeout != NULL)
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*timeout = valid_timeval_to_timeval64 (tv32);
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return r;
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# endif /* __ASSUME_PSELECT */
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#endif
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}
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#if __TIMESIZE != 64
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libc_hidden_def (__select64)
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int
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__select (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
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struct timeval *timeout)
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{
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struct __timeval64 tv64, *ptv64 = NULL;
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if (timeout != NULL)
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{
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tv64 = valid_timeval_to_timeval64 (*timeout);
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ptv64 = &tv64;
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}
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int r = __select64 (nfds, readfds, writefds, exceptfds, ptv64);
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if (timeout != NULL)
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/* The remanining timeout will be always less the input TIMEOUT. */
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*timeout = valid_timeval64_to_timeval (tv64);
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return r;
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}
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#endif
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libc_hidden_def (__select)
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weak_alias (__select, select)
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weak_alias (__select, __libc_select)
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