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Annotation of 43BSDTahoe/lib/libc/gen/setenv.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Copyright (c) 1987 Regents of the University of California.
                      3:  * All rights reserved.
                      4:  *
                      5:  * Redistribution and use in source and binary forms are permitted
                      6:  * provided that the above copyright notice and this paragraph are
                      7:  * duplicated in all such forms and that any documentation,
                      8:  * advertising materials, and other materials related to such
                      9:  * distribution and use acknowledge that the software was developed
                     10:  * by the University of California, Berkeley.  The name of the
                     11:  * University may not be used to endorse or promote products derived
                     12:  * from this software without specific prior written permission.
                     13:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     14:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     15:  * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     16:  */
                     17: 
                     18: #if defined(LIBC_SCCS) && !defined(lint)
                     19: static char sccsid[] = "@(#)setenv.c   5.2 (Berkeley) 6/27/88";
                     20: #endif /* LIBC_SCCS and not lint */
                     21: 
                     22: #include <sys/types.h>
                     23: #include <stdio.h>
                     24: 
                     25: /*
                     26:  * setenv --
                     27:  *     Set the value of the environmental variable "name" to be
                     28:  *     "value".  If rewrite is set, replace any current value.
                     29:  */
                     30: setenv(name, value, rewrite)
                     31:        register char *name, *value;
                     32:        int rewrite;
                     33: {
                     34:        extern char **environ;
                     35:        static int alloced;                     /* if allocated space before */
                     36:        register char *C;
                     37:        int l_value, offset;
                     38:        char *malloc(), *realloc(), *_findenv();
                     39: 
                     40:        if (*value == '=')                      /* no `=' in value */
                     41:                ++value;
                     42:        l_value = strlen(value);
                     43:        if ((C = _findenv(name, &offset))) {    /* find if already exists */
                     44:                if (!rewrite)
                     45:                        return(0);
                     46:                if (strlen(C) >= l_value) {     /* old larger; copy over */
                     47:                        while (*C++ = *value++);
                     48:                        return(0);
                     49:                }
                     50:        }
                     51:        else {                                  /* create new slot */
                     52:                register int    cnt;
                     53:                register char   **P;
                     54: 
                     55:                for (P = environ, cnt = 0; *P; ++P, ++cnt);
                     56:                if (alloced) {                  /* just increase size */
                     57:                        environ = (char **)realloc((char *)environ,
                     58:                            (u_int)(sizeof(char *) * (cnt + 2)));
                     59:                        if (!environ)
                     60:                                return(-1);
                     61:                }
                     62:                else {                          /* get new space */
                     63:                        alloced = 1;            /* copy old entries into it */
                     64:                        P = (char **)malloc((u_int)(sizeof(char *) *
                     65:                            (cnt + 2)));
                     66:                        if (!P)
                     67:                                return(-1);
                     68:                        bcopy(environ, P, cnt * sizeof(char *));
                     69:                        environ = P;
                     70:                }
                     71:                environ[cnt + 1] = NULL;
                     72:                offset = cnt;
                     73:        }
                     74:        for (C = name; *C && *C != '='; ++C);   /* no `=' in name */
                     75:        if (!(environ[offset] =                 /* name + `=' + value */
                     76:            malloc((u_int)((int)(C - name) + l_value + 2))))
                     77:                return(-1);
                     78:        for (C = environ[offset]; (*C = *name++) && *C != '='; ++C);
                     79:        for (*C++ = '='; *C++ = *value++;);
                     80:        return(0);
                     81: }
                     82: 
                     83: /*
                     84:  * unsetenv(name) --
                     85:  *     Delete environmental variable "name".
                     86:  */
                     87: void
                     88: unsetenv(name)
                     89:        char    *name;
                     90: {
                     91:        extern  char    **environ;
                     92:        register char   **P;
                     93:        int     offset;
                     94: 
                     95:        while (_findenv(name, &offset))         /* if set multiple times */
                     96:                for (P = &environ[offset];; ++P)
                     97:                        if (!(*P = *(P + 1)))
                     98:                                break;
                     99: }

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