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73 lines
2.3 KiB
C
73 lines
2.3 KiB
C
/* blockinput.h - interface to blocking complicated interrupt-driven input.
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Copyright (C) 1989, 1993, 2001-2019 Free Software Foundation, Inc.
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This file is part of GNU Emacs.
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GNU Emacs is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at
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your option) any later version.
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GNU Emacs 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
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#ifndef EMACS_BLOCKINPUT_H
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#define EMACS_BLOCKINPUT_H
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INLINE_HEADER_BEGIN
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/* Emacs should avoid doing anything hairy in a signal handler, because
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so many system functions are non-reentrant. For example, malloc
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and the Xlib functions aren't usually re-entrant, so if they were
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used by the SIGIO handler, we'd lose.
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To avoid this, we make the following requirements:
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* Everyone must evaluate BLOCK_INPUT before performing actions that
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might conflict with a signal handler, and then call UNBLOCK_INPUT
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after performing them. Calls BLOCK_INPUT and UNBLOCK_INPUT may be
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nested.
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* Any complicated interrupt handling code should test
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INPUT_BLOCKED_P, and put off its work until later.
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* If the interrupt handling code wishes, it may set
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pending_signals to a non-zero value. If that flag is set
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when input becomes unblocked, UNBLOCK_INPUT will then read
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input and process timers.
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Historically, Emacs signal handlers did much more than they do now,
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and this caused many BLOCK_INPUT calls to be sprinkled around the code.
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FIXME: Remove calls that aren't needed now. */
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extern volatile int interrupt_input_blocked;
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/* Begin critical section. */
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INLINE void
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block_input (void)
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{
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interrupt_input_blocked++;
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}
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extern void unblock_input (void);
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extern void totally_unblock_input (void);
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extern void unblock_input_to (int);
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/* In critical section? */
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INLINE bool
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input_blocked_p (void)
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{
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return interrupt_input_blocked > 0;
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}
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INLINE_HEADER_END
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#endif /* EMACS_BLOCKINPUT_H */
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