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/*
* Shared command handling for k5start and krenew.
*
* Run a command, possibly a long-running one for which we need to wait.
*
* Written by Russ Allbery <eagle@eyrie.org>
* Copyright 2021 Russ Allbery <eagle@eyrie.org>
* Copyright 1995-1997, 1999-2002, 2004-2005, 2007-2009
* The Board of Trustees of the Leland Stanford Junior University
*
* SPDX-License-Identifier: MIT
*/
#include <config.h>
#include <portable/system.h>
#include <signal.h>
#include <sys/wait.h>
#include <util/command.h>
#include <util/macros.h>
#include <util/messages.h>
/* Global so that it can be used in signal handlers. */
static pid_t global_child_pid;
/*
* Run the given aklog command, returning its exit status. The command must
* be a fully-qualified path.
*/
void
command_run(const char *aklog, bool verbose)
{
int status;
/*
* IRIX 6.5's WEXITSTATUS() macro is broken and can't cope with being
* called directly on the return value of system().
*/
status = system(aklog);
status = WEXITSTATUS(status);
if (verbose)
notice("%s exited with status %d\n", aklog, status);
}
/*
* We need a signal handler for SIGCHLD to be received, but it doesn't do
* anything. We just want the signal to be caught so that select will be
* interrupted.
*/
static void
child_handler(int sig UNUSED)
{
/* Do nothing. */
}
/*
* This handler is installed for signals that should be propagated to the
* child (and ignored by kstart).
*/
static void
propagate_handler(int sig)
{
kill(global_child_pid, sig);
}
/*
* Start a command, returning its PID. Takes the command to run, which will
* be searched for on the path if not fully-qualified, and then the arguments
* to pass to it. If execution fails for some reason, returns -1.
*
* This function should only be called once before a call to finish_command;
* otherwise, the signal handler code won't work properly.
*/
pid_t
command_start(const char *command, char **argv)
{
pid_t child;
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
/* Ignored. */
sa.sa_handler = child_handler;
sa.sa_flags = SA_NOCLDSTOP;
if (sigaction(SIGCHLD, &sa, NULL) < 0)
return -1;
/* Propagated to child process. */
sa.sa_handler = propagate_handler;
sa.sa_flags = 0;
if (sigaction(SIGHUP, &sa, NULL) < 0)
return -1;
if (sigaction(SIGINT, &sa, NULL) < 0)
return -1;
if (sigaction(SIGQUIT, &sa, NULL) < 0)
return -1;
if (sigaction(SIGTERM, &sa, NULL) < 0)
return -1;
child = fork();
if (child < 0)
return -1;
else if (child == 0) {
execvp(command, argv);
return -1;
} else {
global_child_pid = child;
return child;
}
}
/*
* Check to see if the given pid is finished. If it is, put its exit status
* into the second argument, if not NULL, and return 1. Otherwise, return 0,
* or -1 if waitpid failed.
*/
int
command_finish(pid_t child, int *status)
{
int result;
result = waitpid(child, status, WNOHANG);
if (result < 0)
return -1;
if (result == 0)
return 0;
if (status) {
if (WIFEXITED(*status))
*status = WEXITSTATUS(*status);
else if (WIFSIGNALED(*status))
/*
* Use the adjusted process signal as the exit status. This
* duplicates the exit status behavior of bash.
*/
*status = WTERMSIG(*status) + 128;
}
return 1;
}
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