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 5.6 (Berkeley) 06/04/91"; 10 #endif /* LIBC_SCCS and not lint */ 11 12 #include <stddef.h> 13 #include <stdlib.h> 14 #include <string.h> 15 16 /* 17 * setenv -- 18 * Set the value of the environmental variable "name" to be 19 * "value". If rewrite is set, replace any current value. 20 */ 21 setenv(name, value, rewrite) 22 register const char *name; 23 register const char *value; 24 int rewrite; 25 { 26 extern char **environ; 27 static int alloced; /* if allocated space before */ 28 register char *C; 29 int l_value, offset; 30 char *_findenv(); 31 32 if (*value == '=') /* no `=' in value */ 33 ++value; 34 l_value = strlen(value); 35 if ((C = _findenv(name, &offset))) { /* find if already exists */ 36 if (!rewrite) 37 return (0); 38 if (strlen(C) >= l_value) { /* old larger; copy over */ 39 while (*C++ = *value++); 40 return (0); 41 } 42 } else { /* create new slot */ 43 register int cnt; 44 register char **P; 45 46 for (P = environ, cnt = 0; *P; ++P, ++cnt); 47 if (alloced) { /* just increase size */ 48 environ = (char **)realloc((char *)environ, 49 (size_t)(sizeof(char *) * (cnt + 2))); 50 if (!environ) 51 return (-1); 52 } 53 else { /* get new space */ 54 alloced = 1; /* copy old entries into it */ 55 P = (char **)malloc((size_t)(sizeof(char *) * 56 (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 ; 71 for (*C++ = '='; *C++ = *value++; ) 72 ; 73 return (0); 74 } 75 76 /* 77 * unsetenv(name) -- 78 * Delete environmental variable "name". 79 */ 80 void 81 unsetenv(name) 82 const char *name; 83 { 84 extern char **environ; 85 register char **P; 86 int offset; 87 88 while (_findenv(name, &offset)) /* if set multiple times */ 89 for (P = &environ[offset];; ++P) 90 if (!(*P = *(P + 1))) 91 break; 92 } 93