usr/src/lib/libast/common/misc/setenviron.c

   1 /***********************************************************************
   2 *                                                                      *
   3 *               This software is part of the ast package               *
   4 *          Copyright (c) 1985-2010 AT&T Intellectual Property          *
   5 *                      and is licensed under the                       *
   6 *                  Common Public License, Version 1.0                  *
   7 *                    by AT&T Intellectual Property                     *
   8 *                                                                      *
   9 *                A copy of the License is available at                 *
  10 *            http://www.opensource.org/licenses/cpl1.0.txt             *
  11 *         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
  12 *                                                                      *
  13 *              Information and Software Systems Research               *
  14 *                            AT&T Research                             *
  15 *                           Florham Park NJ                            *
  16 *                                                                      *
  17 *                 Glenn Fowler <gsf@research.att.com>                  *
  18 *                  David Korn <dgk@research.att.com>                   *
  19 *                   Phong Vo <kpv@research.att.com>                    *
  20 *                                                                      *
  21 ***********************************************************************/
  22 #pragma prototyped
  23
  24 #include "intercepts.h"
  25
  26 #include <fs3d.h>
  27
  28 /*
  29  * put name=value in the environment
  30  * pointer to value returned
  31  * environ==0 is ok
  32  *
  33  *      setenviron("N=V")       add N=V
  34  *      setenviron("N")         delete N
  35  *      setenviron(0)           expect more (pre-fork optimization)
  36  *
  37  * _ always placed at the top
  38  */
  39
  40 #define INCREMENT       16              /* environ increment            */
  41
  42 char*
  43 setenviron(const char* akey)
  44 {
  45 #undef  setenviron
  46         static char**   envv;           /* recorded environ             */
  47         static char**   next;           /* next free slot               */
  48         static char**   last;           /* last free slot (0)           */
  49         static char     ok[] = "";      /* delete/optimization ok return*/
  50
  51         char*           key = (char*)akey;
  52         register char** v = environ;
  53         register char** p = envv;
  54         register char*  s;
  55         register char*  t;
  56         int             n;
  57
  58         ast.env_serial++;
  59         if (intercepts.intercept_setenviron)
  60                 return (*intercepts.intercept_setenviron)(akey);
  61         if (p && !v)
  62         {
  63                 environ = next = p;
  64                 *++next = 0;
  65         }
  66         else if (p != v || !v)
  67         {
  68                 if (v)
  69                 {
  70                         while (*v++);
  71                         n = v - environ + INCREMENT;
  72                         v = environ;
  73                 }
  74                 else
  75                         n = INCREMENT;
  76                 if (!p || (last - p + 1) < n)
  77                 {
  78                         if (!p && fs3d(FS3D_TEST))
  79                         {
  80                                 /*
  81                                  * kick 3d initialization
  82                                  */
  83
  84                                 close(open(".", O_RDONLY));
  85                                 v = environ;
  86                         }
  87                         if (!(p = newof(p, char*, n, 0)))
  88                                 return 0;
  89                         last = p + n - 1;
  90                 }
  91                 envv = environ = p;
  92                 if (v && v[0] && v[0][0] == '_' && v[0][1] == '=')
  93                         *p++ = *v++;
  94                 else
  95                         *p++ = "_=";
  96                 if (!v)
  97                         *p = 0;
  98                 else
  99                         while (*p = *v++)
 100                                 if (p[0][0] == '_' && p[0][1] == '=')
 101                                         envv[0] = *p;
 102                                 else
 103                                         p++;
 104                 next = p;
 105                 p = envv;
 106         }
 107         else if (next == last)
 108         {
 109                 n = last - v + INCREMENT + 1;
 110                 if (!(p = newof(p, char*, n, 0)))
 111                         return 0;
 112                 last = p + n - 1;
 113                 next = last - INCREMENT;
 114                 envv = environ = p;
 115         }
 116         if (!key)
 117                 return ok;
 118         for (; s = *p; p++)
 119         {
 120                 t = key;
 121                 do
 122                 {
 123                         if (!*t || *t == '=')
 124                         {
 125                                 if (*s == '=')
 126                                 {
 127                                         if (!*t)
 128                                         {
 129                                                 v = p++;
 130                                                 while (*v++ = *p++);
 131                                                 next--;
 132                                                 return ok;
 133                                         }
 134                                         *p = key;
 135                                         return (s = strchr(key, '=')) ? s + 1 : (char*)0;
 136                                 }
 137                                 break;
 138                         }
 139                 } while (*t++ == *s++);
 140         }
 141         if (!(s = strchr(key, '=')))
 142                 return ok;
 143         p = next;
 144         *++next = 0;
 145         *p = key;
 146         return s + 1;
 147 }