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https://github.com/libguestfs/libguestfs.git
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88 lines
2.5 KiB
C
88 lines
2.5 KiB
C
/* libguestfs
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* Copyright (C) 2016 Red Hat Inc.
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*
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* This 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 of the License, or (at your option) any later version.
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*
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* This 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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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <sys/wait.h>
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#include "guestfs.h"
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#include "guestfs-internal.h"
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/**
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* A safe version of L<waitpid(3)> which retries if C<EINTR> is
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* returned.
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*
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* I<Note:> this only needs to be used in the library, or in programs
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* that install a non-restartable C<SIGCHLD> handler (which is not the
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* case for any current libguestfs virt tools).
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*
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* If the main program installs a SIGCHLD handler and sets it to be
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* non-restartable, then what can happen is the library is waiting in
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* a wait syscall, the child exits, C<SIGCHLD> is sent to the process,
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* and the wait syscall returns C<EINTR>. Since the library cannot
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* control the signal handler, we have to instead restart the wait
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* syscall, which is the purpose of this wrapper.
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*/
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int
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guestfs_int_waitpid (guestfs_h *g, pid_t pid, int *status, const char *errmsg)
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{
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again:
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if (waitpid (pid, status, 0) == -1) {
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if (errno == EINTR)
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goto again;
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perrorf (g, "%s: waitpid", errmsg);
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return -1;
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}
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return 0;
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}
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/**
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* Like C<guestfs_int_waitpid>, but ignore errors.
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*/
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void
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guestfs_int_waitpid_noerror (pid_t pid)
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{
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while (waitpid (pid, NULL, 0) == -1 && errno == EINTR)
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;
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}
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/**
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* A safe version of L<wait4(2)> which retries if C<EINTR> is
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* returned.
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*/
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int
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guestfs_int_wait4 (guestfs_h *g, pid_t pid, int *status,
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struct rusage *rusage, const char *errmsg)
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{
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again:
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if (wait4 (pid, status, 0, rusage) == -1) {
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if (errno == EINTR)
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goto again;
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perrorf (g, "%s: wait4", errmsg);
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return -1;
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}
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return 0;
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}
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