1 /* 2 * Copyright (c) 1987, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)setenv.c 8.1 (Berkeley) 06/04/93"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <stddef.h> 13 #include <stdlib.h> 14 #include <string.h> 15 16 char *__findenv __P((const char *, int *)); 17 18 /* 19 * setenv -- 20 * Set the value of the environmental variable "name" to be 21 * "value". If rewrite is set, replace any current value. 22 */ 23 setenv(name, value, rewrite) 24 register const char *name; 25 register const char *value; 26 int rewrite; 27 { 28 extern char **environ; 29 static int alloced; /* if allocated space before */ 30 register char *c; 31 int l_value, offset; 32 33 if (*value == '=') /* no `=' in value */ 34 ++value; 35 l_value = strlen(value); 36 if ((c = __findenv(name, &offset))) { /* find if already exists */ 37 if (!rewrite) 38 return (0); 39 if (strlen(c) >= l_value) { /* old larger; copy over */ 40 while (*c++ = *value++); 41 return (0); 42 } 43 } else { /* create new slot */ 44 register int cnt; 45 register char **p; 46 47 for (p = environ, cnt = 0; *p; ++p, ++cnt); 48 if (alloced) { /* just increase size */ 49 environ = (char **)realloc((char *)environ, 50 (size_t)(sizeof(char *) * (cnt + 2))); 51 if (!environ) 52 return (-1); 53 } 54 else { /* get new space */ 55 alloced = 1; /* copy old entries into it */ 56 p = malloc((size_t)(sizeof(char *) * (cnt + 2))); 57 if (!p) 58 return (-1); 59 bcopy(environ, p, cnt * sizeof(char *)); 60 environ = p; 61 } 62 environ[cnt + 1] = NULL; 63 offset = cnt; 64 } 65 for (c = (char *)name; *c && *c != '='; ++c); /* no `=' in name */ 66 if (!(environ[offset] = /* name + `=' + value */ 67 malloc((size_t)((int)(c - name) + l_value + 2)))) 68 return (-1); 69 for (c = environ[offset]; (*c = *name++) && *c != '='; ++c); 70 for (*c++ = '='; *c++ = *value++;); 71 return (0); 72 } 73 74 /* 75 * unsetenv(name) -- 76 * Delete environmental variable "name". 77 */ 78 void 79 unsetenv(name) 80 const char *name; 81 { 82 extern char **environ; 83 register char **p; 84 int offset; 85 86 while (__findenv(name, &offset)) /* if set multiple times */ 87 for (p = &environ[offset];; ++p) 88 if (!(*p = *(p + 1))) 89 break; 90 } 91