1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License, Version 1.0 only 6 * (the "License"). You may not use this file except in compliance 7 * with the License. 8 * 9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 10 * or http://www.opensolaris.org/os/licensing. 11 * See the License for the specific language governing permissions 12 * and limitations under the License. 13 * 14 * When distributing Covered Code, include this CDDL HEADER in each 15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 16 * If applicable, add the following below this CDDL HEADER, with the 17 * fields enclosed by brackets "[]" replaced with your own identifying 18 * information: Portions Copyright [yyyy] [name of copyright owner] 19 * 20 * CDDL HEADER END 21 */ 22 /* 23 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "%Z%%M% %I% %E% SMI" 28 29 #include "thr_uberdata.h" 30 #include "mtlib.h" 31 32 /* 33 * fork handlers are run in LIFO order. 34 * The libc fork handler is expected to be the first handler installed, 35 * hence would be the last fork handler run in preparation for fork1(). 36 * It is essential that this be so, for other libraries depend on libc 37 * and may grab their own locks before calling into libc. By special 38 * arrangement, the loader runs libc's init section (libc_init()) first. 39 */ 40 41 /* 42 * pthread_atfork(): installs handlers to be called during fork1(). 43 * There is no POSIX API that provides for deletion of atfork handlers. 44 * Collaboration between the loader and libc ensures that atfork 45 * handlers installed by a library are deleted when that library 46 * is unloaded (see _preexec_atfork_unload() in atexit.c). 47 */ 48 #pragma weak _private_pthread_atfork = _pthread_atfork 49 #pragma weak pthread_atfork = _pthread_atfork 50 int 51 _pthread_atfork(void (*prepare)(void), 52 void (*parent)(void), void (*child)(void)) 53 { 54 ulwp_t *self = curthread; 55 uberdata_t *udp = self->ul_uberdata; 56 atfork_t *atfp; 57 atfork_t *head; 58 int error; 59 60 if ((error = fork_lock_enter("pthread_atfork")) != 0) { 61 /* 62 * Cannot call pthread_atfork() from a fork handler. 63 */ 64 fork_lock_exit(); 65 return (error); 66 } 67 if ((atfp = lmalloc(sizeof (atfork_t))) == NULL) { 68 fork_lock_exit(); 69 return (ENOMEM); 70 } 71 atfp->prepare = prepare; 72 atfp->parent = parent; 73 atfp->child = child; 74 if ((head = udp->atforklist) == NULL) { 75 udp->atforklist = atfp; 76 atfp->forw = atfp->back = atfp; 77 } else { 78 head->back->forw = atfp; 79 atfp->forw = head; 80 atfp->back = head->back; 81 head->back = atfp; 82 } 83 fork_lock_exit(); 84 return (0); 85 } 86 87 /* 88 * _prefork_handler() is called by fork1() before it starts processing. 89 * It executes the user installed "prepare" routines in LIFO order (POSIX) 90 */ 91 void 92 _prefork_handler(void) 93 { 94 uberdata_t *udp = curthread->ul_uberdata; 95 atfork_t *atfork_q; 96 atfork_t *atfp; 97 98 if ((atfork_q = udp->atforklist) != NULL) { 99 atfp = atfork_q = atfork_q->back; 100 do { 101 if (atfp->prepare) 102 (*atfp->prepare)(); 103 } while ((atfp = atfp->back) != atfork_q); 104 } 105 } 106 107 /* 108 * _postfork_parent_handler() is called by fork1() after it retuns as parent. 109 * It executes the user installed "parent" routines in FIFO order (POSIX). 110 */ 111 void 112 _postfork_parent_handler(void) 113 { 114 uberdata_t *udp = curthread->ul_uberdata; 115 atfork_t *atfork_q; 116 atfork_t *atfp; 117 118 if ((atfork_q = udp->atforklist) != NULL) { 119 atfp = atfork_q; 120 do { 121 if (atfp->parent) 122 (*atfp->parent)(); 123 } while ((atfp = atfp->forw) != atfork_q); 124 } 125 } 126 127 /* 128 * _postfork_child_handler() is called by fork1() after it returns as child. 129 * It executes the user installed "child" routines in FIFO order (POSIX). 130 */ 131 void 132 _postfork_child_handler(void) 133 { 134 uberdata_t *udp = curthread->ul_uberdata; 135 atfork_t *atfork_q; 136 atfork_t *atfp; 137 138 if ((atfork_q = udp->atforklist) != NULL) { 139 atfp = atfork_q; 140 do { 141 if (atfp->child) 142 (*atfp->child)(); 143 } while ((atfp = atfp->forw) != atfork_q); 144 } 145 } 146