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/* libguestfs
* Copyright (C) 2016 Red Hat Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include "guestfs.h"
#include "guestfs-internal.h"
/**
* A safe version of L<waitpid(3)> which retries if C<EINTR> is
* returned.
*
* I<Note:> this only needs to be used in the library, or in programs
* that install a non-restartable C<SIGCHLD> handler (which is not the
* case for any current libguestfs virt tools).
*
* If the main program installs a SIGCHLD handler and sets it to be
* non-restartable, then what can happen is the library is waiting in
* a wait syscall, the child exits, C<SIGCHLD> is sent to the process,
* and the wait syscall returns C<EINTR>. Since the library cannot
* control the signal handler, we have to instead restart the wait
* syscall, which is the purpose of this wrapper.
*/
int
guestfs_int_waitpid (guestfs_h *g, pid_t pid, int *status, const char *errmsg)
{
again:
if (waitpid (pid, status, 0) == -1) {
if (errno == EINTR)
goto again;
perrorf (g, "%s: waitpid", errmsg);
return -1;
}
return 0;
}
/**
* Like C<guestfs_int_waitpid>, but ignore errors.
*/
void
guestfs_int_waitpid_noerror (pid_t pid)
{
while (waitpid (pid, NULL, 0) == -1 && errno == EINTR)
;
}
/**
* A safe version of L<wait4(2)> which retries if C<EINTR> is
* returned.
*/
int
guestfs_int_wait4 (guestfs_h *g, pid_t pid, int *status,
struct rusage *rusage, const char *errmsg)
{
again:
if (wait4 (pid, status, 0, rusage) == -1) {
if (errno == EINTR)
goto again;
perrorf (g, "%s: wait4", errmsg);
return -1;
}
return 0;
}
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