/* env.c, envread.c, env.h: environ libraryDaniel 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;}