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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- G N A T . C G I --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 2000-2018, AdaCore --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. --
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17 -- --
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18 -- As a special exception under Section 7 of GPL version 3, you are granted --
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19 -- additional permissions described in the GCC Runtime Library Exception, --
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20 -- version 3.1, as published by the Free Software Foundation. --
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21 -- --
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22 -- You should have received a copy of the GNU General Public License and --
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23 -- a copy of the GCC Runtime Library Exception along with this program; --
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24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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25 -- <http://www.gnu.org/licenses/>. --
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26 -- --
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27 -- GNAT was originally developed by the GNAT team at New York University. --
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28 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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29 -- --
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30 ------------------------------------------------------------------------------
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31
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32 -- This is a package to interface a GNAT program with a Web server via the
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33 -- Common Gateway Interface (CGI).
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34
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35 -- Other related packages are:
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36
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37 -- GNAT.CGI.Cookie which deal with Web HTTP Cookies.
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38 -- GNAT.CGI.Debug which output complete CGI runtime environment
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39
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40 -- Basically this package parse the CGI parameter which are a set of key/value
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41 -- pairs. It builds a table whose index is the key and provides some services
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42 -- to deal with this table.
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43
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44 -- Example:
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45
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46 -- Consider the following simple HTML form to capture a client name:
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47
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48 -- <!DOCTYPE HTML PUBLIC "-//W3C//DTD W3 HTML 3.2//EN">
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49 -- <html>
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50 -- <head>
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51 -- <title>My Web Page</title>
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52 -- </head>
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53
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54 -- <body>
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55 -- <form action="/cgi-bin/new_client" method="POST">
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56 -- <input type=text name=client_name>
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57 -- <input type=submit name="Enter">
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58 -- </form>
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59 -- </body>
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60 -- </html>
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61
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62 -- The following program will retrieve the client's name:
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63
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64 -- with GNAT.CGI;
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65
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66 -- procedure New_Client is
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67 -- use GNAT;
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68
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69 -- procedure Add_Client_To_Database (Name : String) is
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70 -- begin
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71 -- ...
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72 -- end Add_Client_To_Database;
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73
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74 -- begin
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75 -- -- Check that we have 2 arguments (there is two inputs tag in
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76 -- -- the HTML form) and that one of them is called "client_name".
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77
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78 -- if CGI.Argument_Count = 2
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79 -- and then CGI.Key_Exists ("client_name")
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80 -- then
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81 -- Add_Client_To_Database (CGI.Value ("client_name"));
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82 -- end if;
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83
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84 -- ...
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85
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86 -- CGI.Put_Header;
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87 -- Text_IO.Put_Line ("<html><body>< ... Ok ... >");
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88
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89 -- exception
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90 -- when CGI.Data_Error =>
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91 -- CGI.Put_Header ("Location: /htdocs/error.html");
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92 -- -- This returns the address of a Web page to be displayed
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93 -- -- using a "Location:" header style.
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94 -- end New_Client;
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95
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96 -- Note that the names in this package interface have been designed so that
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97 -- they read nicely with the CGI prefix. The recommended style is to avoid
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98 -- a use clause for GNAT.CGI, but to include a use clause for GNAT.
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99
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100 -- This package builds up a table of CGI parameters whose memory is not
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101 -- released. A CGI program is expected to be a short lived program and
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102 -- so it is adequate to have the underlying OS free the program on exit.
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103
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104 package GNAT.CGI is
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105
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106 Data_Error : exception;
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107 -- This is raised when there is a problem with the CGI protocol. Either
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108 -- the data could not be retrieved or the CGI environment is invalid.
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109 --
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110 -- The package will initialize itself by parsing the runtime CGI
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111 -- environment during elaboration but we do not want to raise an
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112 -- exception at this time, so the exception Data_Error is deferred
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113 -- and will be raised when calling any services below (except for Ok).
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114
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115 Parameter_Not_Found : exception;
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116 -- This exception is raised when a specific parameter is not found
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117
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118 Default_Header : constant String := "Content-type: text/html";
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119 -- This is the default header returned by Put_Header. If the CGI program
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120 -- returned data is not an HTML page, this header must be change to a
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121 -- valid MIME type.
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122
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123 type Method_Type is (Get, Post);
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124 -- The method used to pass parameter from the Web client to the
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125 -- server. With the GET method parameters are passed via the command
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126 -- line, with the POST method parameters are passed via environment
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127 -- variables. Others methods are not supported by this implementation.
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128
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129 type Metavariable_Name is
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130 (Auth_Type,
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131 Content_Length,
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132 Content_Type,
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133 Document_Root, -- Web server dependent
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134 Gateway_Interface,
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135 HTTP_Accept,
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136 HTTP_Accept_Encoding,
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137 HTTP_Accept_Language,
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138 HTTP_Connection,
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139 HTTP_Cookie,
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140 HTTP_Extension,
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141 HTTP_From,
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142 HTTP_Host,
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143 HTTP_Referer,
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144 HTTP_User_Agent,
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145 Path,
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146 Path_Info,
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147 Path_Translated,
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148 Query_String,
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149 Remote_Addr,
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150 Remote_Host,
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151 Remote_Port, -- Web server dependent
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152 Remote_Ident,
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153 Remote_User,
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154 Request_Method,
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155 Request_URI, -- Web server dependent
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156 Script_Filename, -- Web server dependent
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157 Script_Name,
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158 Server_Addr, -- Web server dependent
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159 Server_Admin, -- Web server dependent
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160 Server_Name,
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161 Server_Port,
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162 Server_Protocol,
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163 Server_Signature, -- Web server dependent
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164 Server_Software);
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165 -- CGI metavariables that are set by the Web server during program
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166 -- execution. All these variables are part of the restricted CGI runtime
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167 -- environment and can be read using Metavariable service. The detailed
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168 -- meanings of these metavariables are out of the scope of this
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169 -- description. Please refer to http://www.w3.org/CGI/ for a description
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170 -- of the CGI specification. Some metavariables are Web server dependent
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171 -- and are not described in the cited document.
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172
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173 procedure Put_Header
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174 (Header : String := Default_Header;
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175 Force : Boolean := False);
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176 -- Output standard CGI header by default. The header string is followed by
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177 -- an empty line. This header must be the first answer sent back to the
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178 -- server. Do nothing if this function has already been called and Force
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179 -- is False.
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180
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181 function Ok return Boolean;
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182 -- Returns True if the CGI environment is valid and False otherwise.
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183 -- Every service used when the CGI environment is not valid will raise
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184 -- the exception Data_Error.
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185
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186 function Method return Method_Type;
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187 -- Returns the method used to call the CGI
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188
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189 function Metavariable
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190 (Name : Metavariable_Name;
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191 Required : Boolean := False) return String;
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192 -- Returns parameter Name value. Returns the null string if Name
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193 -- environment variable is not defined or raises Data_Error if
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194 -- Required is set to True.
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195
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196 function Metavariable_Exists (Name : Metavariable_Name) return Boolean;
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197 -- Returns True if the environment variable Name is defined in
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198 -- the CGI runtime environment and False otherwise.
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199
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200 function URL return String;
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201 -- Returns the URL used to call this script without the parameters.
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202 -- The URL form is: http://<server_name>[:<server_port>]<script_name>
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203
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204 function Argument_Count return Natural;
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205 -- Returns the number of parameters passed to the client. This is the
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206 -- number of input tags in a form or the number of parameters passed to
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207 -- the CGI via the command line.
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208
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209 ---------------------------------------------------
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210 -- Services to retrieve key/value CGI parameters --
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211 ---------------------------------------------------
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212
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213 function Value
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214 (Key : String;
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215 Required : Boolean := False) return String;
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216 -- Returns the parameter value associated to the parameter named Key.
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217 -- If parameter does not exist, returns an empty string if Required
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218 -- is False and raises the exception Parameter_Not_Found otherwise.
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219
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220 function Value (Position : Positive) return String;
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221 -- Returns the parameter value associated with the CGI parameter number
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222 -- Position. Raises Parameter_Not_Found if there is no such parameter
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223 -- (i.e. Position > Argument_Count)
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224
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225 function Key_Exists (Key : String) return Boolean;
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226 -- Returns True if the parameter named Key exists and False otherwise
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227
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228 function Key (Position : Positive) return String;
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229 -- Returns the parameter key associated with the CGI parameter number
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230 -- Position. Raises the exception Parameter_Not_Found if there is no
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231 -- such parameter (i.e. Position > Argument_Count)
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232
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233 generic
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234 with procedure
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235 Action
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236 (Key : String;
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237 Value : String;
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238 Position : Positive;
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239 Quit : in out Boolean);
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240 procedure For_Every_Parameter;
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241 -- Iterate through all existing key/value pairs and call the Action
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242 -- supplied procedure. The Key and Value are set appropriately, Position
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243 -- is the parameter order in the list, Quit is set to True by default.
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244 -- Quit can be set to False to control the iterator termination.
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245
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246 private
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247
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248 function Decode (S : String) return String;
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249 -- Decode Web string S. A string when passed to a CGI is encoded,
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250 -- this function will decode the string to return the original
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251 -- string's content. Every triplet of the form %HH (where H is an
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252 -- hexadecimal number) is translated into the character such that:
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253 -- Hex (Character'Pos (C)) = HH.
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254
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255 end GNAT.CGI;
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