886898baad
Libguestfs wants to use qemu to run a captive appliance. When the program linked to libguestfs exits, we want qemu to be cleaned up. Libguestfs goes to great lengths to do this at the moment: it either forks a separate process to ensure clean-up is done, or it asks libvirt to clean up the qemu process. However this is complicated and not totally reliable. On Linux, FreeBSD and macOS, there are mechanisms to ensure a signal or message is delivered to a process when its parent process goes away. The qemu test suite even uses this mechanism on Linux (see PR_SET_PDEATHSIG in tests/qtest/libqtest.c). In nbdkit we have long had the concept of running nbdkit captively, and we have the nbdkit --exit-with-parent flag to help (https://libguestfs.org/nbdkit-captive.1.html#EXIT-WITH-PARENT) This commit adds the same mechanism. The syntax is: qemu -run-with exit-with-parent=on [...] This is not a feature that most typical users of qemu (for running general purpose, long-lived VMs) should use, so it defaults to off. The exit-with-parent.[ch] files are copied from nbdkit, where they have a 3-clause BSD license which is compatible with qemu: https://gitlab.com/nbdkit/nbdkit/-/tree/master/common/utils?ref_type=heads Thanks: Daniel P. Berrangé <berrange@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Signed-off-by: Richard W.M. Jones <rjones@redhat.com> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
57 lines
2.1 KiB
C
57 lines
2.1 KiB
C
/*
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* SPDX-License-Identifier: BSD-3-Clause
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* Originally derived from nbdkit common/utils/exit-with-parent.h
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* Copyright Red Hat
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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 are
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* met:
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*
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* * 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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*
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* * 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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*
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* * Neither the name of Red Hat nor the names of its contributors may be
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* used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* 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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#ifndef NBDKIT_EXIT_WITH_PARENT_H
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#define NBDKIT_EXIT_WITH_PARENT_H
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/* Test if the feature is available on the platform. */
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static inline bool can_exit_with_parent(void)
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{
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#if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__)
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return true;
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#else
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return false;
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#endif
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}
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/*
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* --exit-with-parent: kill the current process if the parent exits.
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* This may return -1 on error.
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*
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* Note this will abort on platforms where can_exit_with_parent()
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* returned false.
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*/
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extern int set_exit_with_parent(void);
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#endif /* NBDKIT_EXIT_WITH_PARENT_H */
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