1 /*	$NetBSD: detach.c,v 1.2 2017/01/28 21:31:50 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 2015
5  *	Cryptonector LLC.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Cryptonector LLC may not be used to endorse or promote products
16  *    derived from this software without specific prior written
17  *    permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #include <config.h>
33 #include <errno.h>
34 #include <fcntl.h>
35 #ifdef WIN32
36 #include <io.h>
37 #include <stdlib.h>
38 #else
39 #include <unistd.h>
40 #endif
41 #include <krb5/roken.h>
42 
43 #ifdef WIN32
44 #define dup2 _dup2
45 #endif
46 
47 static int pipefds[2] = {-1, -1};
48 
49 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
roken_detach_prep(int argc,char ** argv,char * special_arg)50 roken_detach_prep(int argc, char **argv, char *special_arg)
51 {
52     pid_t child;
53     char buf[1];
54     ssize_t bytes;
55     int status;
56 
57     pipefds[0] = -1;
58     pipefds[1] = -1;
59 
60 #ifdef WIN32
61     if (_pipe(pipefds, 4, O_BINARY) == -1)
62         err(1, "failed to setup to detach daemon (_pipe failed)");
63 #else
64     if (pipe(pipefds) == -1)
65         err(1, "failed to setup to detach daemon (pipe failed)");
66 #endif
67 
68 #ifndef WIN32
69     fflush(stdout);
70     child = fork();
71 #else
72     {
73         intptr_t child_handle;
74 	int write_side;
75         size_t i;
76 	char *fildes;
77         char **new_argv;
78 
79         new_argv = calloc(argc + 2, sizeof(*new_argv));
80         if (new_argv == NULL)
81             err(1, "Out of memory");
82 
83 	write_side = _dup(pipefds[1]); /* The new fd will be inherited */
84 	if (write_side == -1)
85             err(1, "Out of memory");
86 
87 	if (asprintf(&fildes, "%d", write_side) == -1 ||
88 	    fildes == NULL)
89             err(1, "failed to setup to detach daemon (_dup failed)");
90 
91         new_argv[0] = argv[0];
92         new_argv[1] = special_arg;
93         new_argv[2] = fildes;
94         for (i = 1; argv[i] != NULL; i++)
95             new_argv[i + 1] = argv[i];
96 	new_argv[argc + 2] = NULL;
97 
98 	_flushall();
99 	child_handle = spawnvp(_P_NOWAIT, argv[0], new_argv);
100 	if (child_handle == -1)
101 	  child = (pid_t)-1;
102 	else
103 	  child = GetProcessId((HANDLE)child_handle);
104     }
105 #endif
106     if (child == (pid_t)-1)
107         err(1, "failed to setup to fork daemon (fork failed)");
108 
109 #ifndef WIN32
110     if (child == 0) {
111         int fd;
112 
113         (void) close(pipefds[0]);
114         pipefds[0] = -1;
115         /*
116          * Keep stdout/stderr for now so output and errors prior to
117          * detach_finish() can be seen by the user.
118          */
119         fd = open(_PATH_DEVNULL, O_RDWR, 0);
120         if (fd == -1)
121             err(1, "failed to open /dev/null");
122         (void) dup2(fd, STDIN_FILENO);
123         if (fd > STDERR_FILENO)
124             (void) close(fd);
125         return;
126     }
127 #endif
128 
129     (void) close(pipefds[1]);
130     pipefds[1] = -1;
131     do {
132         bytes = read(pipefds[0], buf, sizeof(buf));
133     } while (bytes == -1 && errno == EINTR);
134     (void) close(pipefds[0]);
135     pipefds[0] = -1;
136     if (bytes == -1) {
137         /*
138          * No need to wait for the process.  We've killed it.  If it
139          * doesn't want to exit, we'd have to wait potentially forever,
140          * but we want to indicate failure to the user as soon as
141          * possible.  A wait with timeout would end the same way
142          * (attempting to kill the process).
143          */
144         err(1, "failed to setup daemon child (read from child pipe)");
145     }
146     if (bytes == 0) {
147         warnx("daemon child preparation failed, waiting for child");
148         status = wait_for_process(child);
149         if (SE_IS_ERROR(status) || SE_PROCSTATUS(status) != 0)
150             errx(SE_PROCSTATUS(status),
151                  "daemon child preparation failed (child exited)");
152     }
153     _exit(0);
154 }
155 
156 #ifdef WIN32
157 #ifdef dup2
158 #undef dup2
159 #endif
160 #define dup2 _dup2
161 #endif
162 
163 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
roken_detach_finish(const char * dir,int daemon_child_fd)164 roken_detach_finish(const char *dir, int daemon_child_fd)
165 {
166     char buf[1] = "";
167     ssize_t bytes;
168     int fd;
169 
170     rk_pidfile(NULL);
171     if (pipefds[1] == -1 && daemon_child_fd != -1)
172         pipefds[1] = daemon_child_fd;
173     if (pipefds[0] != -1)
174 	(void) close(pipefds[0]);
175     if (pipefds[1] == -1)
176         return;
177 
178 #ifdef HAVE_SETSID
179     if (setsid() == -1)
180         err(1, "failed to detach from tty");
181 #endif
182 
183 #ifndef WIN32
184     /*
185      * Hopefully we've written any pidfiles by now, if they had to be in
186      * the current directory...
187      *
188      * The daemons do re-open logs and so on, therefore this chdir()
189      * call needs to be optional for testing.
190      */
191     if (dir != NULL && chdir(dir) == -1)
192         err(1, "failed to chdir to /");
193 #endif
194 
195     do {
196         bytes = write(pipefds[1], buf, sizeof(buf));
197     } while (bytes == -1 && errno == EINTR);
198     if (bytes == -1)
199         err(1, "failed to signal parent while detaching");
200     (void) close(pipefds[1]);
201     if (bytes != sizeof(buf))
202         errx(1, "failed to signal parent while detaching");
203 
204     fd = open(_PATH_DEVNULL, O_RDWR, 0);
205     if (fd == -1)
206         err(1, "failed to open /dev/null");
207     /*
208      * Maybe we should check that our output got written, if redirected
209      * to a file.  File utils normally do this.
210      */
211     (void) dup2(fd, STDOUT_FILENO);
212     (void) dup2(fd, STDERR_FILENO);
213     if (fd > 2)
214         (void) close(fd);
215 }
216