lib/sh/getenv.c

   1 /* getenv.c - get environment variable value from the shell's variable
   2               list. */
   3
   4 /* Copyright (C) 1997-2002 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Bash is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include <config.h>
  23
  24 #if defined (CAN_REDEFINE_GETENV)
  25
  26 #if defined (HAVE_UNISTD_H)
  27 #  include <unistd.h>
  28 #endif
  29
  30 #include <bashansi.h>
  31 #include <errno.h>
  32 #include <shell.h>
  33
  34 #ifndef errno
  35 extern int errno;
  36 #endif
  37
  38 extern char **environ;
  39
  40 /* We supply our own version of getenv () because we want library
  41    routines to get the changed values of exported variables. */
  42
  43 /* The NeXT C library has getenv () defined and used in the same file.
  44    This screws our scheme.  However, Bash will run on the NeXT using
  45    the C library getenv (), since right now the only environment variable
  46    that we care about is HOME, and that is already defined.  */
  47 static char *last_tempenv_value = (char *)NULL;
  48
  49 char *
  50 getenv (name)
  51      const char *name;
  52 {
  53   SHELL_VAR *var;
  54
  55   if (name == 0 || *name == '\0')
  56     return ((char *)NULL);
  57
  58   var = find_tempenv_variable ((char *)name);
  59   if (var)
  60     {
  61       FREE (last_tempenv_value);
  62
  63       last_tempenv_value = value_cell (var) ? savestring (value_cell (var)) : (char *)NULL;
  64       return (last_tempenv_value);
  65     }
  66   else if (shell_variables)
  67     {
  68       var = find_variable ((char *)name);
  69       if (var && exported_p (var))
  70         return (value_cell (var));
  71     }
  72   else if (environ)
  73     {
  74       register int i, len;
  75
  76       /* In some cases, s5r3 invokes getenv() before main(); BSD systems
  77          using gprof also exhibit this behavior.  This means that
  78          shell_variables will be 0 when this is invoked.  We look up the
  79          variable in the real environment in that case. */
  80
  81       for (i = 0, len = strlen (name); environ[i]; i++)
  82         {
  83           if ((STREQN (environ[i], name, len)) && (environ[i][len] == '='))
  84             return (environ[i] + len + 1);
  85         }
  86     }
  87
  88   return ((char *)NULL);
  89 }
  90
  91 /* Some versions of Unix use _getenv instead. */
  92 char *
  93 _getenv (name)
  94      const char *name;
  95 {
  96   return (getenv (name));
  97 }
  98
  99 /* SUSv3 says argument is a `char *'; BSD implementations disagree */
 100 int
 101 putenv (str)
 102 #ifndef HAVE_STD_PUTENV
 103      const char *str;
 104 #else
 105      char *str;
 106 #endif
 107 {
 108   SHELL_VAR *var;
 109   char *name, *value;
 110   int offset;
 111
 112   if (str == 0 || *str == '\0')
 113     {
 114       errno = EINVAL;
 115       return -1;
 116     }
 117
 118   offset = assignment (str, 0);
 119   if (str[offset] != '=')
 120     {
 121       errno = EINVAL;
 122       return -1;
 123     }
 124   name = savestring (str);
 125   name[offset] = 0;
 126
 127   value = name + offset + 1;
 128
 129   /* XXX - should we worry about readonly here? */
 130   var = bind_variable (name, value, 0);
 131   if (var == 0)
 132     {
 133       errno = EINVAL;
 134       return -1;
 135     }
 136
 137   VUNSETATTR (var, att_invisible);
 138   VSETATTR (var, att_exported);
 139
 140   return 0;
 141 }
 142
 143 #if 0
 144 int
 145 _putenv (name)
 146 #ifndef HAVE_STD_PUTENV
 147      const char *name;
 148 #else
 149      char *name;
 150 #endif
 151 {
 152   return putenv (name);
 153 }
 154 #endif
 155
 156 int
 157 setenv (name, value, rewrite)
 158      const char *name;
 159      const char *value;
 160      int rewrite;
 161 {
 162   SHELL_VAR *var;
 163   char *v;
 164
 165   if (name == 0 || *name == '\0' || strchr (name, '=') != 0)
 166     {
 167       errno = EINVAL;
 168       return -1;
 169     }
 170
 171   var = 0;
 172   v = (char *)value;    /* some compilers need explicit cast */
 173   /* XXX - should we worry about readonly here? */
 174   if (rewrite == 0)
 175     var = find_variable (name);
 176
 177   if (var == 0)
 178     var = bind_variable (name, v, 0);
 179
 180   if (var == 0)
 181     return -1;
 182
 183   VUNSETATTR (var, att_invisible);
 184   VSETATTR (var, att_exported);
 185
 186   return 0;
 187 }
 188
 189 #if 0
 190 int
 191 _setenv (name, value, rewrite)
 192      const char *name;
 193      const char *value;
 194      int rewrite;
 195 {
 196   return setenv (name, value, rewrite);
 197 }
 198 #endif
 199
 200 /* SUSv3 says unsetenv returns int; existing implementations (BSD) disagree. */
 201
 202 #ifdef HAVE_STD_UNSETENV
 203 #define UNSETENV_RETURN(N)      return(N)
 204 #define UNSETENV_RETTYPE        int
 205 #else
 206 #define UNSETENV_RETURN(N)      return
 207 #define UNSETENV_RETTYPE        void
 208 #endif
 209
 210 UNSETENV_RETTYPE
 211 unsetenv (name)
 212      const char *name;
 213 {
 214   if (name == 0 || *name == '\0' || strchr (name, '=') != 0)
 215     {
 216       errno = EINVAL;
 217       UNSETENV_RETURN(-1);
 218     }
 219
 220   /* XXX - should we just remove the export attribute here? */
 221 #if 1
 222   unbind_variable (name);
 223 #else
 224   SHELL_VAR *v;
 225
 226   v = find_variable (name);
 227   if (v)
 228     VUNSETATTR (v, att_exported);
 229 #endif
 230
 231   UNSETENV_RETURN(0);
 232 }
 233 #endif /* CAN_REDEFINE_GETENV */