1 /* 2 * Copyright (c) 1987 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 */ 7 8 #if defined(LIBC_SCCS) && !defined(lint) 9 static char sccsid[] = "@(#)setenv.c 5.4 (Berkeley) 06/01/90"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <stddef.h> 13 #include <stdlib.h> 14 15 /* 16 * setenv -- 17 * Set the value of the environmental variable "name" to be 18 * "value". If rewrite is set, replace any current value. 19 */ 20 setenv(name, value, rewrite) 21 register char *name, *value; 22 int rewrite; 23 { 24 extern char **environ; 25 static int alloced; /* if allocated space before */ 26 register char *C; 27 int l_value, offset; 28 char *_findenv(); 29 30 if (*value == '=') /* no `=' in value */ 31 ++value; 32 l_value = strlen(value); 33 if ((C = _findenv(name, &offset))) { /* find if already exists */ 34 if (!rewrite) 35 return(0); 36 if (strlen(C) >= l_value) { /* old larger; copy over */ 37 while (*C++ = *value++); 38 return(0); 39 } 40 } 41 else { /* create new slot */ 42 register int cnt; 43 register char **P; 44 45 for (P = environ, cnt = 0; *P; ++P, ++cnt); 46 if (alloced) { /* just increase size */ 47 environ = (char **)realloc((char *)environ, 48 (size_t)(sizeof(char *) * (cnt + 2))); 49 if (!environ) 50 return(-1); 51 } 52 else { /* get new space */ 53 alloced = 1; /* copy old entries into it */ 54 P = (char **)malloc((size_t)(sizeof(char *) * 55 (cnt + 2))); 56 if (!P) 57 return(-1); 58 bcopy(environ, P, cnt * sizeof(char *)); 59 environ = P; 60 } 61 environ[cnt + 1] = NULL; 62 offset = cnt; 63 } 64 for (C = name; *C && *C != '='; ++C); /* no `=' in name */ 65 if (!(environ[offset] = /* name + `=' + value */ 66 malloc((size_t)((int)(C - name) + l_value + 2)))) 67 return(-1); 68 for (C = environ[offset]; (*C = *name++) && *C != '='; ++C); 69 for (*C++ = '='; *C++ = *value++;); 70 return(0); 71 } 72 73 /* 74 * unsetenv(name) -- 75 * Delete environmental variable "name". 76 */ 77 void 78 unsetenv(name) 79 char *name; 80 { 81 extern char **environ; 82 register char **P; 83 int offset; 84 85 while (_findenv(name, &offset)) /* if set multiple times */ 86 for (P = &environ[offset];; ++P) 87 if (!(*P = *(P + 1))) 88 break; 89 } 90