source: azure_iot_hub/trunk/musl-1.1.18/src/process/posix_spawn.c@ 389

Last change on this file since 389 was 389, checked in by coas-nagasima, 5 years ago

ビルドが通るよう更新
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File size: 5.1 KB
Line 
1#define _GNU_SOURCE
2#include <spawn.h>
3#include <sched.h>
4#include <unistd.h>
5#include <signal.h>
6#include <fcntl.h>
7#include <sys/wait.h>
8#include "syscall.h"
9#include "pthread_impl.h"
10#include "fdop.h"
11#include "libc.h"
12
13struct args {
14 int p[2];
15 sigset_t oldmask;
16 const char *path;
17 int (*exec)(const char *, char *const *, char *const *);
18 const posix_spawn_file_actions_t *fa;
19 const posix_spawnattr_t *restrict attr;
20 char *const *argv, *const *envp;
21};
22
23void __get_handler_set(sigset_t *);
24
25static int __sys_dup2(int old, int new)
26{
27#ifdef SYS_dup2
28 return __syscall(SYS_dup2, old, new);
29#else
30 if (old==new) {
31 int r = __syscall(SYS_fcntl, old, F_GETFD);
32 return r<0 ? r : old;
33 } else {
34 return __syscall(SYS_dup3, old, new, 0);
35 }
36#endif
37}
38
39static int child(void *args_vp)
40{
41 int i, ret;
42 struct sigaction sa = {0};
43 struct args *args = args_vp;
44 int p = args->p[1];
45 const posix_spawn_file_actions_t *fa = args->fa;
46 const posix_spawnattr_t *restrict attr = args->attr;
47 sigset_t hset;
48
49 close(args->p[0]);
50
51 /* All signal dispositions must be either SIG_DFL or SIG_IGN
52 * before signals are unblocked. Otherwise a signal handler
53 * from the parent might get run in the child while sharing
54 * memory, with unpredictable and dangerous results. To
55 * reduce overhead, sigaction has tracked for us which signals
56 * potentially have a signal handler. */
57 __get_handler_set(&hset);
58 for (i=1; i<_NSIG; i++) {
59 if ((attr->__flags & POSIX_SPAWN_SETSIGDEF)
60 && sigismember(&attr->__def, i)) {
61 sa.sa_handler = SIG_DFL;
62 } else if (sigismember(&hset, i)) {
63 if (i-32<3U) {
64 sa.sa_handler = SIG_IGN;
65 } else {
66 __libc_sigaction(i, 0, &sa);
67 if (sa.sa_handler==SIG_IGN) continue;
68 sa.sa_handler = SIG_DFL;
69 }
70 } else {
71 continue;
72 }
73 __libc_sigaction(i, &sa, 0);
74 }
75
76 if (attr->__flags & POSIX_SPAWN_SETSID)
77 if ((ret=__syscall(SYS_setsid)) < 0)
78 goto fail;
79
80 if (attr->__flags & POSIX_SPAWN_SETPGROUP)
81 if ((ret=__syscall(SYS_setpgid, 0, attr->__pgrp)))
82 goto fail;
83
84 /* Use syscalls directly because the library functions attempt
85 * to do a multi-threaded synchronized id-change, which would
86 * trash the parent's state. */
87 if (attr->__flags & POSIX_SPAWN_RESETIDS)
88 if ((ret=__syscall(SYS_setgid, __syscall(SYS_getgid))) ||
89 (ret=__syscall(SYS_setuid, __syscall(SYS_getuid))) )
90 goto fail;
91
92 if (fa && fa->__actions) {
93 struct fdop *op;
94 int fd;
95 for (op = fa->__actions; op->next; op = op->next);
96 for (; op; op = op->prev) {
97 /* It's possible that a file operation would clobber
98 * the pipe fd used for synchronizing with the
99 * parent. To avoid that, we dup the pipe onto
100 * an unoccupied fd. */
101 if (op->fd == p) {
102 ret = __syscall(SYS_dup, p);
103 if (ret < 0) goto fail;
104 __syscall(SYS_close, p);
105 p = ret;
106 }
107 switch(op->cmd) {
108 case FDOP_CLOSE:
109 __syscall(SYS_close, op->fd);
110 break;
111 case FDOP_DUP2:
112 if ((ret=__sys_dup2(op->srcfd, op->fd))<0)
113 goto fail;
114 break;
115 case FDOP_OPEN:
116 fd = __sys_open(op->path, op->oflag, op->mode);
117 if ((ret=fd) < 0) goto fail;
118 if (fd != op->fd) {
119 if ((ret=__sys_dup2(fd, op->fd))<0)
120 goto fail;
121 __syscall(SYS_close, fd);
122 }
123 break;
124 }
125 }
126 }
127
128 /* Close-on-exec flag may have been lost if we moved the pipe
129 * to a different fd. We don't use F_DUPFD_CLOEXEC above because
130 * it would fail on older kernels and atomicity is not needed --
131 * in this process there are no threads or signal handlers. */
132 __syscall(SYS_fcntl, p, F_SETFD, FD_CLOEXEC);
133
134 pthread_sigmask(SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
135 ? &attr->__mask : &args->oldmask, 0);
136
137 args->exec(args->path, args->argv, args->envp);
138 ret = -errno;
139
140fail:
141 /* Since sizeof errno < PIPE_BUF, the write is atomic. */
142 ret = -ret;
143 if (ret) while (__syscall(SYS_write, p, &ret, sizeof ret) < 0);
144 _exit(127);
145}
146
147
148int __posix_spawnx(pid_t *restrict res, const char *restrict path,
149 int (*exec)(const char *, char *const *, char *const *),
150 const posix_spawn_file_actions_t *fa,
151 const posix_spawnattr_t *restrict attr,
152 char *const argv[restrict], char *const envp[restrict])
153{
154 pid_t pid;
155 char stack[1024+PATH_MAX];
156 int ec=0, cs;
157 struct args args;
158
159 if (pipe2(args.p, O_CLOEXEC))
160 return errno;
161
162 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
163
164 args.path = path;
165 args.exec = exec;
166 args.fa = fa;
167 args.attr = attr ? attr : &(const posix_spawnattr_t){0};
168 args.argv = argv;
169 args.envp = envp;
170 pthread_sigmask(SIG_BLOCK, SIGALL_SET, &args.oldmask);
171
172 pid = __clone(child, stack+sizeof stack,
173 CLONE_VM|CLONE_VFORK|SIGCHLD, &args);
174 close(args.p[1]);
175
176 if (pid > 0) {
177 if (read(args.p[0], &ec, sizeof ec) != sizeof ec) ec = 0;
178 else waitpid(pid, &(int){0}, 0);
179 } else {
180 ec = -pid;
181 }
182
183 close(args.p[0]);
184
185 if (!ec && res) *res = pid;
186
187 pthread_sigmask(SIG_SETMASK, &args.oldmask, 0);
188 pthread_setcancelstate(cs, 0);
189
190 return ec;
191}
192
193int posix_spawn(pid_t *restrict res, const char *restrict path,
194 const posix_spawn_file_actions_t *fa,
195 const posix_spawnattr_t *restrict attr,
196 char *const argv[restrict], char *const envp[restrict])
197{
198 return __posix_spawnx(res, path, execve, fa, attr, argv, envp);
199}
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