setenv.c (3752B)
1 /* 2 * Copyright (c) 1987, 1993 3 * The Regents of the University of California. 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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <stddef.h> 35 #include <stdlib.h> 36 #include <string.h> 37 38 char *__findenv(const char *, int *); 39 40 /* 41 * setenv -- 42 * Set the value of the environmental variable "name" to be 43 * "value". If rewrite is set, replace any current value. 44 */ 45 int 46 setenv(name, value, rewrite) 47 const char *name; 48 const char *value; 49 int rewrite; 50 { 51 extern char **environ; 52 static char **alloced; /* if allocated space before */ 53 char *c; 54 int l_value, offset; 55 56 if (*value == '=') /* no `=' in value */ 57 ++value; 58 l_value = strlen(value); 59 if ((c = __findenv(name, &offset))) { /* find if already exists */ 60 if (!rewrite) 61 return (0); 62 if (strlen(c) >= l_value) { /* old larger; copy over */ 63 while ( (*c++ = *value++) ); 64 return (0); 65 } 66 } else { /* create new slot */ 67 int cnt; 68 char **p; 69 70 for (p = environ, cnt = 0; *p; ++p, ++cnt); 71 if (alloced == environ) { /* just increase size */ 72 p = (char **)realloc((char *)environ, 73 (size_t)(sizeof(char *) * (cnt + 2))); 74 if (!p) 75 return (-1); 76 alloced = environ = p; 77 } 78 else { /* get new space */ 79 /* copy old entries into it */ 80 p = malloc((size_t)(sizeof(char *) * (cnt + 2))); 81 if (!p) 82 return (-1); 83 memcpy(p, environ, cnt * sizeof(char *)); 84 alloced = environ = p; 85 } 86 environ[cnt + 1] = NULL; 87 offset = cnt; 88 } 89 for (c = (char *)name; *c && *c != '='; ++c); /* no `=' in name */ 90 if (!(environ[offset] = /* name + `=' + value */ 91 malloc((size_t)((int)(c - name) + l_value + 2)))) 92 return (-1); 93 for (c = environ[offset]; (*c = *name++) && *c != '='; ++c); 94 for (*c++ = '='; (*c++ = *value++); ); 95 return (0); 96 } 97 98 /* 99 * unsetenv(name) -- 100 * Delete environmental variable "name". 101 */ 102 int 103 unsetenv(name) 104 const char *name; 105 { 106 extern char **environ; 107 char **p; 108 int offset; 109 110 while (__findenv(name, &offset)) /* if set multiple times */ 111 for (p = &environ[offset];; ++p) 112 if (!(*p = *(p + 1))) 113 break; 114 return 0; 115 }