source: trunk/minix/lib/other/putenv.c@ 20

/*
 * (c) copyright 1989 by the Vrije Universiteit, Amsterdam, The Netherlands.
 * See the copyright notice in the ACK home directory, in the file "Copyright".
 */
/* $Header: /cvsup/minix/src/lib/other/putenv.c,v 1.1.1.1.8.1 2006/05/03 21:13:45 beng Exp $ */

#include        <stdlib.h>
#include        <string.h>

#define ENTRY_INC       10
#define rounded(x)      (((x / ENTRY_INC) + 1) * ENTRY_INC)

extern _CONST char ***_penviron;

int
putenv(name)
char *name;
{
        register _CONST char **v = *_penviron;
        register char *r;
        static int size = 0;
        /* When size != 0, it contains the number of entries in the
         * table (including the final NULL pointer). This means that the
         * last non-null entry  is environ[size - 2].
         */

        if (!name) return 0;
        if (*_penviron == NULL) return 1;
        if (r = strchr(name, '=')) {
                register _CONST char *p, *q;

                *r = '\0';

                if (v != NULL) {
                        while ((p = *v) != NULL) {
                                q = name;
                                while (*q && (*q++ == *p++))
                                        /* EMPTY */ ;
                                if (*q || (*p != '=')) {
                                        v++;
                                } else {
                                        /* The name was already in the
                                         * environment.
                                         */
                                        *r = '=';
                                        *v = name;
                                        return 0;
                                }
                        }
                }
                *r = '=';
                v = *_penviron;
        }

        if (!size) {
                register _CONST char **p;
                register int i = 0;

                if (v)
                        do {
                                i++;
                        } while (*v++);
                if (!(v = malloc(rounded(i) * sizeof(char **))))
                        return 1;
                size = i;
                p = *_penviron;
                *_penviron = v;
                while (*v++ = *p++);            /* copy the environment */
                v = *_penviron;
        } else if (!(size % ENTRY_INC)) {
                if (!(v = realloc(*_penviron, rounded(size) * sizeof(char **))))
                        return 1;
                *_penviron = v;
        }
        v[size - 1] = name;
        v[size] = NULL;
        size++;
        return 0;
}