/* * Copyright (c) 1998 Michael Smith. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $Id: environment.c,v 1.1.1.1 1998/08/20 08:19:55 msmith Exp $ * */ /* * Manage an environment-like space in which string variables may be stored. * Provide support for some method-like operations for setting/retrieving * variables in order to allow some type strength. */ #include "stand.h" #include static void env_discard(struct env_var *ev); struct env_var *environ = NULL; /* * Look up (name) and return it's env_var structure. */ struct env_var * env_getenv(const char *name) { struct env_var *ev; for (ev = environ; ev != NULL; ev = ev->ev_next) if (!strcmp(ev->ev_name, name)) break; return(ev); } /* * Some notes: * * If the EV_VOLATILE flag is set, a copy of the variable is made. * If EV_DYNAMIC is set, the the variable has been allocated with * malloc and ownership transferred to the environment. * If (value) is NULL, the variable is set but has no value. */ int env_setenv(const char *name, int flags, void *value, ev_sethook_t sethook, ev_unsethook_t unsethook) { struct env_var *ev, *curr, *last; if ((ev = env_getenv(name)) != NULL) { /* * If there's a set hook, let it do the work (unless we are working * for one already. */ if ((ev->ev_sethook != NULL) && !(flags & EV_NOHOOK)) return(ev->ev_sethook(ev, flags, value)); } else { /* * New variable; create and sort into list */ ev = malloc(sizeof(struct env_var)); ev->ev_name = strdup(name); ev->ev_value = NULL; /* hooks can only be set when the variable is instantiated */ ev->ev_sethook = sethook; ev->ev_unsethook = unsethook; /* Sort into list */ ev->ev_prev = NULL; ev->ev_next = NULL; /* Search for the record to insert before */ for (last = NULL, curr = environ; curr != NULL; last = curr, curr = curr->ev_next) { if (strcmp(ev->ev_name, curr->ev_name) < 0) { if (curr->ev_prev) { curr->ev_prev->ev_next = ev; } else { environ = ev; } ev->ev_next = curr; ev->ev_prev = curr->ev_prev; curr->ev_prev = ev; break; } } if (curr == NULL) { if (last == NULL) { environ = ev; } else { last->ev_next = ev; ev->ev_prev = last; } } } /* If there is data in the variable, discard it */ if (ev->ev_value != NULL) free(ev->ev_value); /* If we have a new value, use it */ if (flags & EV_VOLATILE) { ev->ev_value = strdup(value); } else { ev->ev_value = value; } /* Keep the flag components that are relevant */ ev->ev_flags = flags & (EV_DYNAMIC); return(0); } char * getenv(const char *name) { struct env_var *ev; /* Set but no value gives empty string */ if ((ev = env_getenv(name)) != NULL) { if (ev->ev_value != NULL) return(ev->ev_value); return(""); } return(NULL); } int setenv(const char *name, char *value, int overwrite) { /* No guarantees about state, always assume volatile */ if (overwrite || (env_getenv(name) == NULL)) return(env_setenv(name, EV_VOLATILE, value, NULL, NULL)); return(0); } int putenv(const char *string) { char *value, *copy; int result; copy = strdup(string); if ((value = strchr(copy, '=')) != NULL) *(value++) = 0; result = setenv(copy, value, 1); free(copy); return(result); } int unsetenv(const char *name) { struct env_var *ev; int err; err = 0; if ((ev = env_getenv(name)) == NULL) { err = ENOENT; } else { if (ev->ev_unsethook != NULL) err = ev->ev_unsethook(ev); if (err == 0) { env_discard(ev); } } return(err); } static void env_discard(struct env_var *ev) { if (ev->ev_prev) ev->ev_prev->ev_next = ev->ev_next; if (ev->ev_next) ev->ev_next->ev_prev = ev->ev_prev; if (environ == ev) environ = ev->ev_next; free(ev->ev_name); if (ev->ev_flags & EV_DYNAMIC) free(ev->ev_value); free(ev); } int env_noset(struct env_var *ev, int flags, void *value) { return(EPERM); } int env_nounset(struct env_var *ev) { return(EPERM); }