scoutos / prex-0.9.0 / usr / lib / posix / process / fork.c @ 03e9c04a
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1 | 03e9c04a | Brad Neuman | /*
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2 | * Copyright (c) 2005-2006, Kohsuke Ohtani
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the author nor the names of any co-contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | */
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29 | |||
30 | #include <sys/prex.h> |
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31 | #include <sys/posix.h> |
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32 | #include <sys/signal.h> |
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33 | #include <ipc/proc.h> |
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34 | #include <ipc/fs.h> |
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35 | #include <ipc/ipc.h> |
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36 | |||
37 | #include <stddef.h> |
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38 | #include <setjmp.h> |
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39 | #include <errno.h> |
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40 | #include <unistd.h> |
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41 | |||
42 | static void __child_entry(void); |
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43 | |||
44 | static jmp_buf __fork_env;
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45 | |||
46 | /*
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47 | * fork() - fork for MMU system.
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48 | *
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49 | * RETURN VALUE:
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50 | *
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51 | * fork() returns 0 to the child process and return the process
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52 | * ID of the child process to the parent process. Or, -1 will be
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53 | * returned to the parent process if error.
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54 | *
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55 | * ERRORS:
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56 | *
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57 | * EAGAIN
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58 | * ENOMEM
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59 | *
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60 | * NOTE:
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61 | *
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62 | * Since no thread is created by task_create(), thread_create()
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63 | * must be called follwing task_crate(). But, when new thread is
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64 | * created by thread_create(), the stack pointer of new thread is
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65 | * used at thread_create() although the stack image is copied at
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66 | * task_create(). So, the stack pointer must be reset to same
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67 | * address of thread_create() before calling task_create();
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68 | * This is a little tricky...
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69 | *
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70 | * The new process is an exact copy of the calling process
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71 | * except as detailed below:
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72 | * - Process IDs are different.
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73 | * - tms_* is set to 0.
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74 | * - Alarm clock is set to 0.
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75 | * - Opend semaphore is inherited.
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76 | * - Pending signals are cleared.
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77 | *
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78 | * - File lock is not inherited.
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79 | * - File descriptor is shared.
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80 | * - Directory stream is shared.
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81 | */
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82 | static pid_t
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83 | fork(void)
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84 | { |
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85 | struct msg m;
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86 | task_t tsk; |
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87 | thread_t t; |
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88 | int error;
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89 | pid_t pid; |
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90 | |||
91 | /* Save current stack pointer */
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92 | if (setjmp(__fork_env) == 0) { |
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93 | /*
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94 | * Create new task
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95 | */
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96 | error = task_create(task_self(), VM_COPY, &tsk); |
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97 | if (error) {
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98 | errno = error; |
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99 | return -1; |
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100 | } |
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101 | if ((error = thread_create(tsk, &t)) != 0) { |
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102 | task_terminate(tsk); |
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103 | errno = error; |
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104 | return -1; |
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105 | } |
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106 | /*
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107 | * Notify to process server
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108 | */
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109 | m.hdr.code = PS_FORK; |
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110 | m.data[0] = tsk; /* child task */ |
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111 | m.data[1] = 0; /* fork type */ |
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112 | if (__posix_call(__proc_obj, &m, sizeof(m), 1) != 0) |
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113 | return -1; |
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114 | pid = m.data[0];
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115 | |||
116 | /*
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117 | * Notify to file system server
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118 | */
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119 | m.hdr.code = FS_FORK; |
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120 | m.data[0] = tsk; /* child task */ |
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121 | if (__posix_call(__fs_obj, &m, sizeof(m), 1) != 0) |
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122 | return -1; |
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123 | |||
124 | /*
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125 | * Start child task
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126 | */
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127 | thread_load(t, __child_entry, NULL);
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128 | thread_resume(t); |
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129 | } else {
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130 | /*
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131 | * Child task
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132 | */
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133 | #ifdef _REENTRANT
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134 | error = mutex_init(&__sig_lock); |
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135 | #endif
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136 | __sig_pending = 0;
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137 | return 0; |
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138 | } |
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139 | return pid;
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140 | } |
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141 | |||
142 | static void |
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143 | __child_entry(void)
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144 | { |
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145 | |||
146 | longjmp(__fork_env, 1);
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147 | /* NOTREACHED */
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148 | } |
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149 | |||
150 | pid_t |
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151 | vfork(void)
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152 | { |
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153 | |||
154 | return fork();
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155 | } |