Annotation of prex-old/usr/lib/posix/process/fork_nommu.c, Revision 1.1.1.1
1.1 nbrk 1: /*
2: * Copyright (c) 2006, Kohsuke Ohtani
3: * All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: * 3. Neither the name of the author nor the names of any co-contributors
14: * may be used to endorse or promote products derived from this software
15: * without specific prior written permission.
16: *
17: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27: * SUCH DAMAGE.
28: */
29:
30: #include <prex/prex.h>
31: #include <prex/posix.h>
32: #include <prex/signal.h>
33: #include <server/proc.h>
34: #include <server/fs.h>
35: #include <server/stdmsg.h>
36:
37: #include <stddef.h>
38: #include <setjmp.h>
39: #include <errno.h>
40:
41: static void __parent_entry(void);
42: static void __child_entry(void);
43:
44: static jmp_buf __fork_env;
45: static pid_t __child_pid;
46: static thread_t __parent_th;
47:
48: /*
49: * vfork() - vfork for No-MMU system.
50: *
51: * RETURN VALUE:
52: *
53: * vfork() returns 0 to the child process and return the process
54: * ID of the child process to the parent process. Or, -1 will be
55: * returned to the parent process if error.
56: *
57: * ERRORS:
58: *
59: * EAGAIN
60: * ENOMEM
61: *
62: * NOTE:
63: *
64: * Since no thread is created by task_create(), thread_create()
65: * must be called follwing task_crate(). But, when new thread is
66: * created by thread_create(), the stack pointer of new thread is
67: * used at thread_create() although the stack image is copied at
68: * task_create(). So, the stack pointer must be reset to same
69: * address of thread_create() before calling task_create();
70: * This is a little tricky...
71: *
72: * The new process is an exact copy of the calling process
73: * except as detailed below:
74: * - Process IDs are different.
75: * - tms_* is set to 0.
76: * - Alarm clock is set to 0.
77: * - Opend semaphore is inherited.
78: * - Pending signals are cleared.
79: *
80: * - File lock is not inherited.
81: * - File descriptor is same
82: * - Directory stream is same
83: */
84: pid_t
85: vfork(void)
86: {
87: struct msg m;
88: task_t tsk;
89: thread_t th;
90: int err, sts, prio;
91:
92: /* Save current stack pointer */
93: sts = setjmp(__fork_env);
94: if (sts == 0) {
95: /*
96: * Create new task
97: */
98: if ((err = task_create(task_self(), VM_SHARE, &tsk)) != 0) {
99: errno = err;
100: return -1;
101: }
102: if ((err = thread_create(tsk, &th)) != 0) {
103: task_terminate(tsk);
104: errno = err;
105: return -1;
106: }
107: /*
108: * Notify to file system server
109: */
110: m.hdr.code = FS_FORK;
111: m.data[0] = tsk; /* child task */
112: if (__posix_call(__fs_obj, &m, sizeof(m), 1) != 0)
113: return -1;
114:
115: /*
116: * Notify to process server
117: */
118: m.hdr.code = PS_FORK;
119: m.data[0] = tsk; /* child task */
120: m.data[1] = 1; /* fork type */
121: if (__posix_call(__proc_obj, &m, sizeof(m), 1) != 0)
122: return -1;
123: __child_pid = m.data[0];
124:
125: /*
126: * Start child task.
127: *
128: * TODO:
129: * In order to synchronize the execution, we change
130: * the child's priority to lower value. This ugly hack
131: * will be replaced by some other methods...
132: */
133: thread_load(th, __child_entry, NULL);
134: thread_getprio(th, &prio);
135: thread_setprio(th, prio + 1);
136: thread_resume(th);
137:
138: /*
139: * Suspend until child process calls exec() or exit()
140: */
141: __parent_th = thread_self();
142: task_suspend(task_self());
143:
144: } else if (sts == 1) {
145: /*
146: * Child task
147: */
148: thread_load(__parent_th, __parent_entry, NULL);
149:
150: th = thread_self();
151: thread_getprio(th, &prio);
152: thread_setprio(th, prio - 1);
153:
154: #ifdef _REENTRANT
155: err = mutex_init(&__sig_lock);
156: #endif
157: __sig_pending = 0;
158: return 0;
159: }
160: return __child_pid;
161: }
162:
163: static void
164: __parent_entry(void)
165: {
166:
167: longjmp(__fork_env, 2);
168: /* NOTREACHED */
169: }
170:
171: static void
172: __child_entry(void)
173: {
174:
175: longjmp(__fork_env, 1);
176: /* NOTREACHED */
177: }
178:
179: /*
180: * fork() is not supported on NOMMU system.
181: */
182: pid_t
183: fork(void)
184: {
185:
186: return ENOSYS;
187: }
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