1 /*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2012 Roy Marples <roy@marples.name>
4 * All rights reserved
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28 /* This implementation of posix_spawn is only suitable for the needs of dhcpcd
29 * but it could easily be extended to other applications. */
30
31 #include <sys/types.h>
32 #include <sys/wait.h>
33
34 #include <errno.h>
35 #include <signal.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <unistd.h>
39
40 #include "../common.h"
41 #include "posix_spawn.h"
42
43 #ifndef _NSIG
44 #ifdef _SIG_MAXSIG
45 #define _NSIG _SIG_MAXSIG + 1
46 #else
47 /* Guess */
48 #define _NSIG SIGPWR + 1
49 #endif
50 #endif
51
52 extern char **environ;
53
54 static int
posix_spawnattr_handle(const posix_spawnattr_t * attrp)55 posix_spawnattr_handle(const posix_spawnattr_t *attrp)
56 {
57 struct sigaction sa;
58 int i;
59
60 if (attrp->posix_attr_flags & POSIX_SPAWN_SETSIGMASK)
61 sigprocmask(SIG_SETMASK, &attrp->posix_attr_sigmask, NULL);
62
63 if (attrp->posix_attr_flags & POSIX_SPAWN_SETSIGDEF) {
64 memset(&sa, 0, sizeof(sa));
65 sa.sa_handler = SIG_DFL;
66 for (i = 1; i < _NSIG; i++) {
67 if (sigismember(&attrp->posix_attr_sigdefault, i)) {
68 if (sigaction(i, &sa, NULL) == -1)
69 return -1;
70 }
71 }
72 }
73
74 return 0;
75 }
76
77 inline static int
is_vfork_safe(short int flags)78 is_vfork_safe(short int flags)
79 {
80 return !(flags & (POSIX_SPAWN_SETSIGDEF | POSIX_SPAWN_SETSIGMASK));
81 }
82
83 int
posix_spawn(pid_t * pid,const char * path,const posix_spawn_file_actions_t * file_actions,const posix_spawnattr_t * attrp,char * const argv[],char * const envp[])84 posix_spawn(pid_t *pid, const char *path,
85 const posix_spawn_file_actions_t *file_actions,
86 const posix_spawnattr_t *attrp,
87 char *const argv[], char *const envp[])
88 {
89 short int flags;
90 pid_t p;
91 volatile int error;
92
93 error = 0;
94 flags = attrp ? attrp->posix_attr_flags : 0;
95 if (file_actions == NULL && is_vfork_safe(flags))
96 p = vfork();
97 else
98 #ifdef THERE_IS_NO_FORK
99 return ENOSYS;
100 #else
101 p = fork();
102 #endif
103 switch (p) {
104 case -1:
105 return errno;
106 case 0:
107 if (attrp) {
108 error = posix_spawnattr_handle(attrp);
109 if (error)
110 _exit(127);
111 }
112 execve(path, argv, envp);
113 error = errno;
114 _exit(127);
115 default:
116 if (error != 0)
117 waitpid(p, NULL, WNOHANG);
118 else if (pid != NULL)
119 *pid = p;
120 return error;
121 }
122 }
123
124 int
posix_spawnattr_init(posix_spawnattr_t * attr)125 posix_spawnattr_init(posix_spawnattr_t *attr)
126 {
127
128 memset(attr, 0, sizeof(*attr));
129 attr->posix_attr_flags = 0;
130 sigprocmask(0, NULL, &attr->posix_attr_sigmask);
131 sigemptyset(&attr->posix_attr_sigdefault);
132 return 0;
133 }
134
135 int
posix_spawnattr_setflags(posix_spawnattr_t * attr,short flags)136 posix_spawnattr_setflags(posix_spawnattr_t *attr, short flags)
137 {
138
139 attr->posix_attr_flags = flags;
140 return 0;
141 }
142
143 int
posix_spawnattr_setsigmask(posix_spawnattr_t * attr,const sigset_t * sigmask)144 posix_spawnattr_setsigmask(posix_spawnattr_t *attr, const sigset_t *sigmask)
145 {
146
147 attr->posix_attr_sigmask = *sigmask;
148 return 0;
149 }
150
151 int
posix_spawnattr_setsigdefault(posix_spawnattr_t * attr,const sigset_t * sigmask)152 posix_spawnattr_setsigdefault(posix_spawnattr_t *attr, const sigset_t *sigmask)
153 {
154
155 attr->posix_attr_sigdefault = *sigmask;
156 return 0;
157 }
158