ack/lang/cem/libcc.ansi/core/stdlib/putenv.c
David Given d1cdb07719 Realise that the libc core can safely call other libc core functions, even if
they're not defined in the core: so putw() can call stdio stuff, for example.
So the earlier concept of pureness isn't necessary. Rename accordingly.
2018-06-21 23:24:23 +02:00

89 lines
1.5 KiB
C

/*
* (c) copyright 1989 by the Vrije Universiteit, Amsterdam, The Netherlands.
* See the copyright notice in the ACK home directory, in the file "Copyright".
*/
/* $Id$ */
#include <stdlib.h>
#include <string.h>
#define ENTRY_INC 10
#define rounded(x) (((x / ENTRY_INC) + 1) * ENTRY_INC)
extern char** environ;
int putenv(char* name)
{
register char** v = environ;
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 (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 = environ;
}
if (!size)
{
register char** p;
register int i = 0;
if (v)
do
{
i++;
} while (*v++);
if (!(v = malloc(rounded(i) * sizeof(char**))))
return 1;
size = i;
p = environ;
environ = v;
while (*v++ = *p++)
; /* copy the environment */
v = environ;
}
else if (!(size % ENTRY_INC))
{
if (!(v = realloc(environ, rounded(size) * sizeof(char**))))
return 1;
environ = v;
}
v[size - 1] = name;
v[size] = NULL;
size++;
return 0;
}