//分析为什么要在system阻塞SIGCHLD,执行完后解除此阻塞
int main(int argc, const char *argv[])
{
int ret, i;
signal(SIGCHLD, sig_handler);
pid_t pid;
pid = fork();
if (pid==0) {
sleep(3);
exit(11);
}
if (1) {
//bad
ret = system_bad("sleep 1");
if (ret) {
printf("system ret is fail: %s\n", strerror(-ret));
}else{
printf("system ret is success\n");
}
pause();
}else{
//ok
ret = system_ok("sleep 1");
if (ret) {
printf("system ret is fail: %s\n", strerror(-ret));
}else{
printf("system ret is success\n");
}
}
return 0;
}
int main(int argc, const char *argv[])
{
int ret;
ret = system_ok("sleep 20");
printf("system ret is %d\n", ret);
return 0;
}
/*
* Background process -- runs with privilege.
*/
static void
down_root_server (const int fd, char *command, const char *argv[], const char *envp[], const int verb)
{
const char *p[3];
char *command_line = NULL;
char *argv_cat = NULL;
int i;
/*
* Do initialization
*/
if (DEBUG (verb))
fprintf (stderr, "DOWN-ROOT: BACKGROUND: INIT command='%s'\n", command);
/*
* Tell foreground that we initialized successfully
*/
if (send_control (fd, RESPONSE_INIT_SUCCEEDED) == -1)
{
fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [1]\n");
goto done;
}
/*
* Build command line
*/
if (string_array_len (argv) >= 2)
argv_cat = build_command_line (&argv[1]);
else
argv_cat = build_command_line (NULL);
p[0] = command;
p[1] = argv_cat;
p[2] = NULL;
command_line = build_command_line (p);
/*
* Save envp in environment
*/
for (i = 0; envp[i]; ++i)
{
putenv ((char *)envp[i]);
}
/*
* Event loop
*/
while (1)
{
int command_code;
int status;
/* get a command from foreground process */
command_code = recv_control (fd);
if (DEBUG (verb))
fprintf (stderr, "DOWN-ROOT: BACKGROUND: received command code: %d\n", command_code);
switch (command_code)
{
case COMMAND_RUN_SCRIPT:
status = system (command_line);
if (system_ok (status)) /* Succeeded */
{
if (send_control (fd, RESPONSE_SCRIPT_SUCCEEDED) == -1)
{
fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [2]\n");
goto done;
}
}
else /* Failed */
{
if (send_control (fd, RESPONSE_SCRIPT_FAILED) == -1)
{
fprintf (stderr, "DOWN-ROOT: BACKGROUND: write error on response socket [3]\n");
goto done;
}
}
break;
case COMMAND_EXIT:
goto done;
case -1:
fprintf (stderr, "DOWN-ROOT: BACKGROUND: read error on command channel\n");
goto done;
default:
fprintf (stderr, "DOWN-ROOT: BACKGROUND: unknown command code: code=%d, exiting\n",
command_code);
goto done;
}
}
done:
if (argv_cat)
free (argv_cat);
if (command_line)
free (command_line);
if (DEBUG (verb))
fprintf (stderr, "DOWN-ROOT: BACKGROUND: EXIT\n");
return;
}
