/* 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_goodbye(i) int i;

{

 alloc_free(environ[i]);

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

 environ[en] = 0;

}

static char *null = 0;

void env_clear()

{

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

 else environ = &null;

}

static void env_unsetlen(s,len) 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);

}

int env_unset(s) char *s;

{

 if (!env_isinit) if (!env_init()) return 0;

 env_unsetlen(s,str_len(s));

 return 1;

}

static int env_add(s) char *s;

{

 char *t;

 t = env_findeq(s);

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

 if (en == ea)

  {

   ea += 30;

   if (!alloc_re(&environ,(en + 1) * sizeof(char *),(ea + 1) * sizeof(char *)))

    { ea = en; return 0; }

  }

 environ[en++] = s;

 environ[en] = 0;

 return 1;

}

int env_put(s) char *s;

{

 char *u;

 if (!env_isinit) if (!env_init()) return 0;

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

 if (!u) return 0;

 str_copy(u,s);

 if (!env_add(u)) { alloc_free(u); return 0; }

 return 1;

}

int env_put2(s,t) char *s; char *t;

{

 char *u;

 int slen;

 if (!env_isinit) if (!env_init()) return 0;

 slen = str_len(s);

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

 if (!u) return 0;

 str_copy(u,s);

 u[slen] = '=';

 str_copy(u + slen + 1,t);

 if (!env_add(u)) { alloc_free(u); return 0; }

 return 1;

}

int env_init()

{

 char **newenviron;

 int i;

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

 ea = en + 10;

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

 if (!newenviron) return 0;

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

  {

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

   if (!newenviron[en])

    {

     for (i = 0;i < en;++i) alloc_free(newenviron[i]);

     alloc_free(newenviron);

     return 0;

    }

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

  }

 newenviron[en] = 0;

 environ = newenviron;

 env_isinit = 1;

 return 1;

}