1794251add
When waiting for child processes using "wait" or if "set -T" is in effect, a signal interrupts the wait. Make sure there is no window where the signal handler may be invoked (setting a flag) just before going to sleep. There is a similar race condition in the shell language, but scripts can avoid it by exiting from the trap handler or enforcing synchronization using a fifo. If SIGCHLD is not trapped, a signal handler must be installed for it. Only install this handler for the duration of the wait to avoid triggering unexpected [EINTR] errors elsewhere. Note that for some reason only SIGINT and SIGQUIT interrupt a "wait" command. This remains the case.
50 lines
2.0 KiB
C
50 lines
2.0 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Kenneth Almquist.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)trap.h 8.3 (Berkeley) 6/5/95
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* $FreeBSD$
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*/
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extern int pendingsigs;
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extern int in_dotrap;
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extern volatile sig_atomic_t gotwinch;
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void clear_traps(void);
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int have_traps(void);
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void setsignal(int);
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void ignoresig(int);
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int issigchldtrapped(void);
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void onsig(int);
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void dotrap(void);
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void setinteractive(int);
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void exitshell(int) __dead2;
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void exitshell_savedstatus(void) __dead2;
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