environment.c revision 64185
155714Skris/* 255714Skris * Copyright (c) 1998 Michael Smith. 355714Skris * All rights reserved. 455714Skris * 555714Skris * Redistribution and use in source and binary forms, with or without 655714Skris * modification, are permitted provided that the following conditions 755714Skris * are met: 8296465Sdelphij * 1. Redistributions of source code must retain the above copyright 955714Skris * notice, this list of conditions and the following disclaimer. 1055714Skris * 2. Redistributions in binary form must reproduce the above copyright 1155714Skris * notice, this list of conditions and the following disclaimer in the 1255714Skris * documentation and/or other materials provided with the distribution. 1355714Skris * 1455714Skris * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15296465Sdelphij * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 1655714Skris * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 1755714Skris * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 1855714Skris * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 1955714Skris * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 2055714Skris * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 2155714Skris * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22296465Sdelphij * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 2355714Skris * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 2455714Skris * SUCH DAMAGE. 2555714Skris * 2655714Skris * $FreeBSD: head/lib/libstand/environment.c 64185 2000-08-03 09:08:29Z jhb $ 2755714Skris * 2855714Skris */ 2955714Skris 3055714Skris/* 3155714Skris * Manage an environment-like space in which string variables may be stored. 3255714Skris * Provide support for some method-like operations for setting/retrieving 3355714Skris * variables in order to allow some type strength. 3455714Skris */ 3555714Skris 3655714Skris#include "stand.h" 37296465Sdelphij 3855714Skris#include <string.h> 3955714Skris 40296465Sdelphijstatic void env_discard(struct env_var *ev); 4155714Skris 4255714Skrisstruct env_var *environ = NULL; 4355714Skris 4455714Skris/* 4555714Skris * Look up (name) and return it's env_var structure. 4655714Skris */ 4755714Skrisstruct env_var * 4855714Skrisenv_getenv(const char *name) 4955714Skris{ 5055714Skris struct env_var *ev; 5155714Skris 52296465Sdelphij for (ev = environ; ev != NULL; ev = ev->ev_next) 5355714Skris if (!strcmp(ev->ev_name, name)) 5455714Skris break; 5555714Skris return(ev); 5655714Skris} 5755714Skris 5855714Skris/* 5955714Skris * Some notes: 6055714Skris * 6155714Skris * If the EV_VOLATILE flag is set, a copy of the variable is made. 6255714Skris * If EV_DYNAMIC is set, the the variable has been allocated with 6355714Skris * malloc and ownership transferred to the environment. 6455714Skris * If (value) is NULL, the variable is set but has no value. 65109998Smarkm */ 66296465Sdelphijint 67296465Sdelphijenv_setenv(const char *name, int flags, const void *value, 68296465Sdelphij ev_sethook_t sethook, ev_unsethook_t unsethook) 6955714Skris{ 70296465Sdelphij struct env_var *ev, *curr, *last; 71296465Sdelphij 72296465Sdelphij if ((ev = env_getenv(name)) != NULL) { 73296465Sdelphij /* 74109998Smarkm * If there's a set hook, let it do the work (unless we are working 75296465Sdelphij * for one already. 76296465Sdelphij */ 77296465Sdelphij if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) 78296465Sdelphij return(ev->ev_sethook(ev, flags, value)); 79109998Smarkm } else { 80296465Sdelphij 81296465Sdelphij /* 82296465Sdelphij * New variable; create and sort into list 83296465Sdelphij */ 84296465Sdelphij ev = malloc(sizeof(struct env_var)); 85296465Sdelphij ev->ev_name = strdup(name); 86296465Sdelphij ev->ev_value = NULL; 87296465Sdelphij /* hooks can only be set when the variable is instantiated */ 88296465Sdelphij ev->ev_sethook = sethook; 89296465Sdelphij ev->ev_unsethook = unsethook; 90296465Sdelphij 91296465Sdelphij /* Sort into list */ 92296465Sdelphij ev->ev_prev = NULL; 93296465Sdelphij ev->ev_next = NULL; 9455714Skris /* Search for the record to insert before */ 95109998Smarkm for (last = NULL, curr = environ; 96296465Sdelphij curr != NULL; 97296465Sdelphij last = curr, curr = curr->ev_next) { 98296465Sdelphij 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