/* env.c, envread.c, env.h: environ library

Daniel J. Bernstein, djb@silverton.berkeley.edu.

Depends on str.h, alloc.h.

Requires environ.

19960113: rewrite. warning: interface is different.

No known patent problems.

*/

#include "str.h"

#include "alloc.h"

#include "env.h"

int env_isinit = 0; /* if env_isinit: */

static int ea; /* environ is a pointer to ea+1 char*'s. */

static int en; /* the first en of those are ALLOCATED. environ[en] is 0. */

static void env_init(void);

static void env_goodbye(int i)

{

alloc_free(environ[i]);

environ[i] = environ[--en];

environ[en] = 0;

}

static char *null = 0;

void env_clear(void)

{

if (env_isinit) while (en) env_goodbye(0);

else environ = &null;

}

static void env_unsetlen(const char *s,int len)

{

int i;

for (i = en - 1;i >= 0;--i)

if (!str_diffn(s,environ[i],len))

if (environ[i][len] == '=')

env_goodbye(i);

}

void env_unset(const char *s)

{

env_init();

env_unsetlen(s,str_len(s));

}

static void env_add(char *s)

{

const char *t;

t = env_findeq(s);

if (t) env_unsetlen(s,t - s);

if (en == ea)

{

ea += 30;

alloc_re((void**)environ,(en + 1) * sizeof(char *),(ea + 1) * sizeof(char *));

}

environ[en++] = s;

environ[en] = 0;

}

void env_put(char *s)

{

char *u;

env_init();

u = alloc(str_len(s) + 1);

str_copy(u,s);

env_add(u);

}

void env_put2(const char *s,const char *t)

{

char *u;

int slen;

env_init();

slen = str_len(s);

u = alloc(slen + str_len(t) + 2);

str_copy(u,s);

u[slen] = '=';

str_copy(u + slen + 1,t);

env_add(u);

}

static void env_init(void)

{

char **newenviron;

if (env_isinit) return;

for (en = 0;environ[en];++en) ;

ea = en + 10;

newenviron = (char **) alloc((ea + 1) * sizeof(char *));

for (en = 0;environ[en];++en)

{

newenviron[en] = alloc(str_len(environ[en]) + 1);

str_copy(newenviron[en],environ[en]);

}

newenviron[en] = 0;

environ = newenviron;

env_isinit = 1;

}