environment.c revision 84221
1/* 2 * Copyright (c) 1998 Michael Smith. 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 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27#include <sys/cdefs.h> 28__FBSDID("$FreeBSD: head/lib/libstand/environment.c 84221 2001-09-30 22:28:01Z dillon $"); 29 30/* 31 * Manage an environment-like space in which string variables may be stored. 32 * Provide support for some method-like operations for setting/retrieving 33 * variables in order to allow some type strength. 34 */ 35 36#include "stand.h" 37 38#include <string.h> 39 40static void env_discard(struct env_var *ev); 41 42struct env_var *environ = NULL; 43 44/* 45 * Look up (name) and return it's env_var structure. 46 */ 47struct env_var * 48env_getenv(const char *name) 49{ 50 struct env_var *ev; 51 52 for (ev = environ; ev != NULL; ev = ev->ev_next) 53 if (!strcmp(ev->ev_name, name)) 54 break; 55 return(ev); 56} 57 58/* 59 * Some notes: 60 * 61 * If the EV_VOLATILE flag is set, a copy of the variable is made. 62 * If EV_DYNAMIC is set, the the variable has been allocated with 63 * malloc and ownership transferred to the environment. 64 * If (value) is NULL, the variable is set but has no value. 65 */ 66int 67env_setenv(const char *name, int flags, const void *value, 68 ev_sethook_t sethook, ev_unsethook_t unsethook) 69{ 70 struct env_var *ev, *curr, *last; 71 72 if ((ev = env_getenv(name)) != NULL) { 73 /* 74 * If there's a set hook, let it do the work (unless we are working 75 * for one already. 76 */ 77 if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 78 return(ev->ev_sethook(ev, flags, value)); 79 } else { 80 81 /* 82 * New variable; create and sort into list 83 */ 84 ev = malloc(sizeof(struct env_var)); 85 ev->ev_name = strdup(name); 86 ev->ev_value = NULL; 87 /* hooks can only be set when the variable is instantiated */ 88 ev->ev_sethook = sethook; 89 ev->ev_unsethook = unsethook; 90 91 /* Sort into list */ 92 ev->ev_prev = NULL; 93 ev->ev_next = NULL; 94 /* Search for the record to insert before */ 95 for (last = NULL, curr = environ; 96 curr != NULL; 97 last = curr, curr = curr->ev_next) { 98 99 if (strcmp(ev->ev_name, curr->ev_name) < 0) { 100 if (curr->ev_prev) { 101 curr->ev_prev->ev_next = ev; 102 } else { 103 environ = ev; 104 } 105 ev->ev_next = curr; 106 ev->ev_prev = curr->ev_prev; 107 curr->ev_prev = ev; 108 break; 109 } 110 } 111 if (curr == NULL) { 112 if (last == NULL) { 113 environ = ev; 114 } else { 115 last->ev_next = ev; 116 ev->ev_prev = last; 117 } 118 } 119 } 120 121 /* If there is data in the variable, discard it */ 122 if (ev->ev_value != NULL) 123 free(ev->ev_value); 124 125 /* If we have a new value, use it */ 126 if (flags & EV_VOLATILE) { 127 ev->ev_value = strdup(value); 128 } else { 129 ev->ev_value = value; 130 } 131 132 /* Keep the flag components that are relevant */ 133 ev->ev_flags = flags & (EV_DYNAMIC); 134 135 return(0); 136} 137 138char * 139getenv(const char *name) 140{ 141 struct env_var *ev; 142 143 /* Set but no value gives empty string */ 144 if ((ev = env_getenv(name)) != NULL) { 145 if (ev->ev_value != NULL) 146 return(ev->ev_value); 147 return(""); 148 } 149 return(NULL); 150} 151 152int 153setenv(const char *name, const char *value, int overwrite) 154{ 155 /* No guarantees about state, always assume volatile */ 156 if (overwrite || (env_getenv(name) == NULL)) 157 return(env_setenv(name, EV_VOLATILE, value, NULL, NULL)); 158 return(0); 159} 160 161int 162putenv(const char *string) 163{ 164 char *value, *copy; 165 int result; 166 167 copy = strdup(string); 168 if ((value = strchr(copy, '=')) != NULL) 169 *(value++) = 0; 170 result = setenv(copy, value, 1); 171 free(copy); 172 return(result); 173} 174 175int 176unsetenv(const char *name) 177{ 178 struct env_var *ev; 179 int err; 180 181 err = 0; 182 if ((ev = env_getenv(name)) == NULL) { 183 err = ENOENT; 184 } else { 185 if (ev->ev_unsethook != NULL) 186 err = ev->ev_unsethook(ev); 187 if (err == 0) { 188 env_discard(ev); 189 } 190 } 191 return(err); 192} 193 194static void 195env_discard(struct env_var *ev) 196{ 197 if (ev->ev_prev) 198 ev->ev_prev->ev_next = ev->ev_next; 199 if (ev->ev_next) 200 ev->ev_next->ev_prev = ev->ev_prev; 201 if (environ == ev) 202 environ = ev->ev_next; 203 free(ev->ev_name); 204 if (ev->ev_flags & EV_DYNAMIC) 205 free(ev->ev_value); 206 free(ev); 207} 208 209int 210env_noset(struct env_var *ev, int flags, void *value) 211{ 212 return(EPERM); 213} 214 215int 216env_nounset(struct env_var *ev) 217{ 218 return(EPERM); 219} 220