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1 //======================================================================== |
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2 // |
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3 // getenv.cxx |
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4 // |
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5 // Implementation of the ISO C standard getenv() function |
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6 // |
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7 //======================================================================== |
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8 //####COPYRIGHTBEGIN#### |
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9 // |
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10 // ------------------------------------------- |
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11 // The contents of this file are subject to the Cygnus eCos Public License |
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12 // Version 1.0 (the "License"); you may not use this file except in |
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13 // compliance with the License. You may obtain a copy of the License at |
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14 // http://sourceware.cygnus.com/ecos |
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15 // |
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16 // Software distributed under the License is distributed on an "AS IS" |
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17 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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18 // License for the specific language governing rights and limitations under |
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19 // the License. |
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20 // |
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21 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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22 // September 30, 1998. |
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23 // |
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24 // The Initial Developer of the Original Code is Cygnus. Portions created |
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25 // by Cygnus are Copyright (C) 1998 Cygnus Solutions. All Rights Reserved. |
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26 // ------------------------------------------- |
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27 // |
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28 //####COPYRIGHTEND#### |
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29 //======================================================================== |
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30 //#####DESCRIPTIONBEGIN#### |
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31 // |
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32 // Author(s): jlarmour |
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33 // Contributors: jlarmour@cygnus.co.uk |
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34 // Date: 1998-08-31 |
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35 // Purpose: |
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36 // Description: |
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37 // Usage: |
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38 // |
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39 //####DESCRIPTIONEND#### |
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40 // |
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41 //======================================================================== |
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42 |
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43 // CONFIGURATION |
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44 |
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45 #include <pkgconf/libc.h> // Configuration header |
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46 |
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47 // Include the C library? |
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48 #if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT) |
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49 |
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50 // INCLUDES |
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51 |
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52 #include <cyg/infra/cyg_type.h> // Common type definitions and support |
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53 #include <cyg/infra/cyg_ass.h> // Tracing support |
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54 #include <cyg/infra/cyg_trac.h> // Tracing support |
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55 #include <stdlib.h> // Main header for stdlib functions |
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56 #include <string.h> // strchr(), strlen() and strncmp() |
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57 #include "clibincl/stdlibsupp.hxx" // Support for stdlib functions |
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58 |
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59 |
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60 // VARIABLES |
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61 |
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62 externC char **environ; // standard definition of environ |
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63 |
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64 // EXPORTED SYMBOLS |
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65 |
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66 externC char * |
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67 getenv( const char *name ) CYGPRI_LIBC_WEAK_ALIAS("_getenv"); |
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68 |
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69 |
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70 // FUNCTIONS |
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71 |
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72 extern char * |
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73 _getenv( const char *name ) |
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74 { |
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75 // This function assumes the POSIX 1003.1 layout of the environment |
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76 // in the environ variable, i.e. extern char **environ is a pointer |
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77 // to an array of character pointers to the environment strings |
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78 // (POSIX 3.1.2.2 and 2.6). |
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79 // |
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80 // getenv() searches the environment list for a string of the form |
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81 // "name=value" (POSIX 4.6.1). The strings must have this form |
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82 // (POSIX 2.6) |
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83 |
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84 CYG_REPORT_FUNCNAMETYPE( "_getenv", "returning %08x" ); |
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85 |
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86 CYG_PRECONDITION( name != NULL, "getenv() called with NULL string!" ); |
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87 |
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88 CYG_REPORT_FUNCARG1( "name=%s", name ); |
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89 |
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90 CYG_PRECONDITION( environ != NULL, |
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91 "environ not set i.e. environ == NULL" ); |
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92 |
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93 CYG_CHECK_DATA_PTR( environ, "environ isn't a valid pointer!" ); |
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94 |
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95 CYG_CHECK_DATA_PTR( name, "name isn't a valid pointer!" ); |
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96 |
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97 // check name doesn't contain '=' |
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98 CYG_PRECONDITION( strchr(name, '=') == NULL, |
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99 "name contains '='!" ); |
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100 |
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101 char **env_str_p; |
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102 cyg_ucount32 len = strlen( name ); |
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103 |
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104 for (env_str_p = environ; *env_str_p != NULL; ++env_str_p ) { |
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105 |
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106 CYG_CHECK_DATA_PTR( env_str_p, |
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107 "current environment string isn't valid!" ); |
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108 |
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109 CYG_CHECK_DATA_PTR( *env_str_p, |
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110 "current environment string isn't valid!" ); |
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111 |
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112 // do we have a match? |
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113 if ( !strncmp(*env_str_p, name, len) ) { |
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114 // but it could be just a prefix i.e. we could have |
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115 // matched MYNAMEFRED when we're looking for just MYNAME, so: |
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116 |
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117 if ( (*env_str_p)[len] == '=' ) { |
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118 // we got a match |
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119 CYG_REPORT_RETVAL( *env_str_p + len + 1 ); |
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120 |
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121 return (*env_str_p + len + 1); |
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122 } // if |
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123 } // if |
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124 |
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125 // check the next pointer isn't NULL, as we're about to dereference |
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126 // it |
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127 CYG_ASSERT( env_str_p+1 != NULL, |
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128 "environment contains a NULL pointer!" ); |
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129 } // for |
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130 |
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131 CYG_REPORT_RETVAL( NULL ); |
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132 return NULL; |
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133 } // getenv() |
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134 |
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135 |
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136 #endif // if defined(CYGPKG_LIBC) && defined(CYGPKG_LIBC_ENVIRONMENT) |
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137 |
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138 // EOF getenv.cxx |
