BSD 4_3_Tahoe release

[unix-history] / usr / src / lib / libc / gen / setenv.c

/*
* Copyright (c) 1987 Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley.  The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)setenv.c    5.2 (Berkeley) 6/27/88";
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <stdio.h>

/*
* setenv --
*      Set the value of the environmental variable "name" to be
*      "value".  If rewrite is set, replace any current value.
*/
setenv(name, value, rewrite)
       register char *name, *value;
       int rewrite;
{
       extern char **environ;
       static int alloced;                     /* if allocated space before */
       register char *C;
       int l_value, offset;
       char *malloc(), *realloc(), *_findenv();

       if (*value == '=')                      /* no `=' in value */
               ++value;
       l_value = strlen(value);
       if ((C = _findenv(name, &offset))) {    /* find if already exists */
               if (!rewrite)
                       return(0);
               if (strlen(C) >= l_value) {     /* old larger; copy over */
                       while (*C++ = *value++);
                       return(0);
               }
       }
       else {                                  /* create new slot */
               register int    cnt;
               register char   **P;

               for (P = environ, cnt = 0; *P; ++P, ++cnt);
               if (alloced) {                  /* just increase size */
                       environ = (char **)realloc((char *)environ,
                           (u_int)(sizeof(char *) * (cnt + 2)));
                       if (!environ)
                               return(-1);
               }
               else {                          /* get new space */
                       alloced = 1;            /* copy old entries into it */
                       P = (char **)malloc((u_int)(sizeof(char *) *
                           (cnt + 2)));
                       if (!P)
                               return(-1);
                       bcopy(environ, P, cnt * sizeof(char *));
                       environ = P;
               }
               environ[cnt + 1] = NULL;
               offset = cnt;
       }
       for (C = name; *C && *C != '='; ++C);   /* no `=' in name */
       if (!(environ[offset] =                 /* name + `=' + value */
           malloc((u_int)((int)(C - name) + l_value + 2))))
               return(-1);
       for (C = environ[offset]; (*C = *name++) && *C != '='; ++C);
       for (*C++ = '='; *C++ = *value++;);
       return(0);
}

/*
* unsetenv(name) --
*      Delete environmental variable "name".
*/
void
unsetenv(name)
       char    *name;
{
       extern  char    **environ;
       register char   **P;
       int     offset;

       while (_findenv(name, &offset))         /* if set multiple times */
               for (P = &environ[offset];; ++P)
                       if (!(*P = *(P + 1)))
                               break;
}