Annotation of prex-old/usr/lib/posix/process/fork_nommu.c, Revision 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: }
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to fork_nommu.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / prex-old / usr / lib / posix / process