1 /* $OpenBSD: setenv.c,v 1.9 2005/08/08 08:05:37 espie Exp $ */ 2 /* 3 * Copyright (c) 1987 Regents of the University of California. 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <stdlib.h> 32 #include <string.h> 33 34 char *__findenv(const char *name, int *offset); 35 36 extern char **environ; 37 38 /* 39 * setenv -- 40 * Set the value of the environmental variable "name" to be 41 * "value". If rewrite is set, replace any current value. 42 */ 43 int 44 setenv(const char *name, const char *value, int rewrite) 45 { 46 static char **lastenv; /* last value of environ */ 47 char *C; 48 int l_value, offset; 49 50 if (*value == '=') /* no `=' in value */ 51 ++value; 52 l_value = strlen(value); 53 if ((C = __findenv(name, &offset))) { /* find if already exists */ 54 if (!rewrite) 55 return (0); 56 if (strlen(C) >= l_value) { /* old larger; copy over */ 57 while ((*C++ = *value++)) 58 ; 59 return (0); 60 } 61 } else { /* create new slot */ 62 size_t cnt; 63 char **P; 64 65 for (P = environ; *P != NULL; P++) 66 ; 67 cnt = P - environ; 68 P = (char **)realloc(lastenv, sizeof(char *) * (cnt + 2)); 69 if (!P) 70 return (-1); 71 if (lastenv != environ) 72 memcpy(P, environ, cnt * sizeof(char *)); 73 lastenv = environ = P; 74 offset = cnt; 75 environ[cnt + 1] = NULL; 76 } 77 for (C = (char *)name; *C && *C != '='; ++C) 78 ; /* no `=' in name */ 79 if (!(environ[offset] = /* name + `=' + value */ 80 malloc((size_t)((int)(C - name) + l_value + 2)))) 81 return (-1); 82 for (C = environ[offset]; (*C = *name++) && *C != '='; ++C) 83 ; 84 for (*C++ = '='; (*C++ = *value++); ) 85 ; 86 return (0); 87 } 88 89 /* 90 * unsetenv(name) -- 91 * Delete environmental variable "name". 92 */ 93 void 94 unsetenv(const char *name) 95 { 96 char **P; 97 int offset; 98 99 while (__findenv(name, &offset)) /* if set multiple times */ 100 for (P = &environ[offset];; ++P) 101 if (!(*P = *(P + 1))) 102 break; 103 } 104