config/gen/platform/win32/env.c

   1 /*
   2  * $Id$
   3  * Copyright (C) 2004-2008, Parrot Foundation.
   4  */
   5
   6 /*
   7
   8 =head1 NAME
   9
  10 config\gen\platform\win32\env.c
  11
  12 =head1 DESCRIPTION
  13
  14 On Windows there are two ways to access the environment.  Either through the
  15 Windows environment block, using GetEnvironmentVariable,
  16 SetEnvironmentVariable and GetEnvironmentStrings, or the C runtime using
  17 _getenv, _putenv and _environ.
  18
  19 Changes through the C runtime are reflected in the environment block, but
  20 changes in the environment block are NOT reflected in the C runtime!
  21
  22 To keep both in sync we always update environment variables through the C
  23 runtime.  Getting an environment variable can be done either way,
  24 whichever is more convenient.
  25
  26 =head2 Functions
  27
  28 =over 4
  29
  30 =cut
  31
  32 */
  33
  34 /*
  35
  36 =item C<void Parrot_setenv(PARROT_INTERP, STRING *str_name, STRING *str_value)>
  37
  38 Sets the environment variable C<str_name> to the value C<str_value>. Creates the
  39 environment variable if it does not exist, and silently overwrite a variable if
  40 it does exist.
  41
  42 =cut
  43
  44 */
  45
  46 void
  47 Parrot_setenv(PARROT_INTERP, STRING *str_name, STRING *str_value)
  48 {
  49     char * const name  = Parrot_str_to_cstring(interp, str_name);
  50     char * const value = Parrot_str_to_cstring(interp, str_value);
  51     assert(name  != NULL);
  52     assert(value != NULL);
  53
  54     {
  55         const int name_len  = strlen(name);
  56         const int value_len = strlen(value);
  57
  58         {
  59             char * const envstring = (char * const)mem_internal_allocate(
  60                     name_len     /* name  */
  61                     + 1          /* '='   */
  62                     + value_len  /* value */
  63                     + 1);        /* string terminator */
  64
  65             /* Save a bit of time, by using the fact we already have the
  66             lengths, avoiding strcat */
  67             strcpy(envstring, name);
  68             strcpy(envstring + name_len, "=");
  69             strcpy(envstring + name_len + 1, value);
  70
  71             Parrot_str_free_cstring(name);
  72             Parrot_str_free_cstring(value);
  73
  74             if (_putenv(envstring) == 0) {
  75                 /* success */
  76                 mem_sys_free(envstring);
  77             }
  78             else {
  79                 mem_sys_free(envstring);
  80                 exit_fatal(1, "Unable to set environment variable %s=%s",
  81                     name, value);
  82             }
  83         }
  84     }
  85 }
  86
  87 /*
  88
  89 =item C<char * Parrot_getenv(PARROT_INTERP, STRING *str_name)>
  90
  91 Gets the environment variable C<str_name>, if it exists. Returns the contents
  92 of the environment variable in a C<malloc>'d memory location that needs to be
  93 freed later.
  94
  95 =cut
  96
  97 */
  98
  99 char *
 100 Parrot_getenv(PARROT_INTERP, ARGIN(STRING *str_name))
 101 {
 102     char * const name = Parrot_str_to_cstring(interp, str_name);
 103     const DWORD size  = GetEnvironmentVariable(name, NULL, 0);
 104     char *buffer      = NULL;
 105
 106     if (size == 0) {
 107         Parrot_str_free_cstring(name);
 108         return NULL;
 109     }
 110     buffer = (char *)mem_sys_allocate(size);
 111     GetEnvironmentVariable(name, buffer, size);
 112     Parrot_str_free_cstring(name);
 113
 114     return buffer;
 115 }
 116
 117 /*
 118
 119 =item C<void Parrot_unsetenv(PARROT_INTERP, STRING *name)>
 120
 121 Deletes an environment variable by assigning an empty string to the specified variable.
 122
 123 =cut
 124
 125 */
 126
 127 void
 128 Parrot_unsetenv(PARROT_INTERP, STRING *name)
 129 {
 130     /* You can remove a variable from the environment by specifying an empty
 131        string -- in other words, by specifying only varname=.
 132            -- _putenv, _wputenv (CRT) documentation
 133     */
 134     Parrot_setenv(interp, name, Parrot_str_new(interp, "", 0));
 135 }
 136
 137 /*
 138
 139 =back
 140
 141 =cut
 142
 143 */
 144
 145 /*
 146  * Local variables:
 147  *   c-file-style: "parrot"
 148  * End:
 149  * vim: expandtab shiftwidth=4:
 150  */