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<pre><a name="line-1"></a><span class='hs-comment'>{-# LANGUAGE CPP, NoImplicitPrelude #-}</span>
<a name="line-2"></a><span class='hs-comment'>{-# LANGUAGE ForeignFunctionInterface #-}</span>
<a name="line-3"></a><span class='hs-comment'>-- | Miscellaneous information about the system environment.</span>
<a name="line-4"></a><span class='hs-keyword'>module</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Environment</span><span class='hs-varop'>.</span><span class='hs-conid'>Compat</span> <span class='hs-layout'>(</span>
<a name="line-5"></a> <span class='hs-varid'>getArgs</span>
<a name="line-6"></a><span class='hs-layout'>,</span> <span class='hs-varid'>getProgName</span>
<a name="line-7"></a><span class='hs-layout'>,</span> <span class='hs-varid'>getEnv</span>
<a name="line-8"></a><span class='hs-layout'>,</span> <span class='hs-varid'>lookupEnv</span>
<a name="line-9"></a><span class='hs-layout'>,</span> <span class='hs-varid'>setEnv</span>
<a name="line-10"></a><span class='hs-layout'>,</span> <span class='hs-varid'>unsetEnv</span>
<a name="line-11"></a><span class='hs-layout'>,</span> <span class='hs-varid'>withArgs</span>
<a name="line-12"></a><span class='hs-layout'>,</span> <span class='hs-varid'>withProgName</span>
<a name="line-13"></a><span class='hs-layout'>,</span> <span class='hs-varid'>getEnvironment</span>
<a name="line-14"></a><span class='hs-layout'>)</span> <span class='hs-keyword'>where</span>
<a name="line-15"></a>
<a name="line-16"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Environment</span>
<a name="line-17"></a>
<a name="line-18"></a><span class='hs-cpp'>#if !(MIN_VERSION_base(4,7,0))</span>
<a name="line-19"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Prelude</span><span class='hs-varop'>.</span><span class='hs-conid'>Compat</span>
<a name="line-20"></a>
<a name="line-21"></a><span class='hs-cpp'># ifdef mingw32_HOST_OS</span>
<a name="line-22"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Control</span><span class='hs-varop'>.</span><span class='hs-conid'>Monad</span>
<a name="line-23"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Foreign</span><span class='hs-varop'>.</span><span class='hs-conid'>C</span>
<a name="line-24"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>Foreign</span><span class='hs-varop'>.</span><span class='hs-conid'>Safe</span>
<a name="line-25"></a><span class='hs-keyword'>import</span> <span class='hs-conid'>GHC</span><span class='hs-varop'>.</span><span class='hs-conid'>Windows</span>
<a name="line-26"></a><span class='hs-cpp'># else</span>
<a name="line-27"></a><span class='hs-keyword'>import</span> <span class='hs-keyword'>qualified</span> <span class='hs-conid'>System</span><span class='hs-varop'>.</span><span class='hs-conid'>Posix</span><span class='hs-varop'>.</span><span class='hs-conid'>Env</span> <span class='hs-keyword'>as</span> <span class='hs-conid'>Posix</span>
<a name="line-28"></a><span class='hs-cpp'># endif</span>
<a name="line-29"></a>
<a name="line-30"></a><span class='hs-cpp'># ifdef mingw32_HOST_OS</span>
<a name="line-31"></a>
<a name="line-32"></a><span class='hs-cpp'># if defined(i386_HOST_ARCH)</span>
<a name="line-33"></a><span class='hs-cpp'># define WINDOWS_CCONV stdcall</span>
<a name="line-34"></a><span class='hs-cpp'># elif defined(x86_64_HOST_ARCH)</span>
<a name="line-35"></a><span class='hs-cpp'># define WINDOWS_CCONV ccall</span>
<a name="line-36"></a><span class='hs-cpp'># else</span>
<a name="line-37"></a><span class='hs-cpp'># error Unknown mingw32 arch</span>
<a name="line-38"></a><span class='hs-cpp'># endif</span>
<a name="line-39"></a>
<a name="line-40"></a><span class='hs-keyword'>foreign</span> <span class='hs-keyword'>import</span> <span class='hs-conid'>WINDOWS_CCONV</span> <span class='hs-keyword'>unsafe</span> <span class='hs-str'>"windows.h GetLastError"</span>
<a name="line-41"></a> <span class='hs-varid'>c_GetLastError</span><span class='hs-keyglyph'>::</span> <span class='hs-conid'>IO</span> <span class='hs-conid'>DWORD</span>
<a name="line-42"></a>
<a name="line-43"></a><a name="eRROR_ENVVAR_NOT_FOUND"></a><span class='hs-definition'>eRROR_ENVVAR_NOT_FOUND</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>DWORD</span>
<a name="line-44"></a><span class='hs-definition'>eRROR_ENVVAR_NOT_FOUND</span> <span class='hs-keyglyph'>=</span> <span class='hs-num'>203</span>
<a name="line-45"></a>
<a name="line-46"></a><span class='hs-cpp'># endif</span>
<a name="line-47"></a>
<a name="line-48"></a><span class='hs-cpp'># if !(MIN_VERSION_base(4,6,0))</span>
<a name="line-49"></a><a name="lookupEnv"></a><span class='hs-comment'>-- | Return the value of the environment variable @var@, or @Nothing@ if</span>
<a name="line-50"></a><span class='hs-comment'>-- there is no such value.</span>
<a name="line-51"></a><span class='hs-comment'>--</span>
<a name="line-52"></a><span class='hs-comment'>-- For POSIX users, this is equivalent to 'System.Posix.Env.getEnv'.</span>
<a name="line-53"></a><span class='hs-definition'>lookupEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-layout'>(</span><span class='hs-conid'>Maybe</span> <span class='hs-conid'>String</span><span class='hs-layout'>)</span>
<a name="line-54"></a><span class='hs-definition'>lookupEnv</span> <span class='hs-varid'>k</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>lookup</span> <span class='hs-varid'>k</span> <span class='hs-varop'>`fmap`</span> <span class='hs-varid'>getEnvironment</span>
<a name="line-55"></a><span class='hs-cpp'># endif</span>
<a name="line-56"></a>
<a name="line-57"></a><a name="setEnv"></a><span class='hs-comment'>-- | @setEnv name value@ sets the specified environment variable to @value@.</span>
<a name="line-58"></a><span class='hs-comment'>--</span>
<a name="line-59"></a><span class='hs-comment'>-- On Windows setting an environment variable to the /empty string/ removes</span>
<a name="line-60"></a><span class='hs-comment'>-- that environment variable from the environment. For the sake of</span>
<a name="line-61"></a><span class='hs-comment'>-- compatibility we adopt that behavior. In particular</span>
<a name="line-62"></a><span class='hs-comment'>--</span>
<a name="line-63"></a><span class='hs-comment'>-- @</span>
<a name="line-64"></a><span class='hs-comment'>-- setEnv name \"\"</span>
<a name="line-65"></a><span class='hs-comment'>-- @</span>
<a name="line-66"></a><span class='hs-comment'>--</span>
<a name="line-67"></a><span class='hs-comment'>-- has the same effect as</span>
<a name="line-68"></a><span class='hs-comment'>--</span>
<a name="line-69"></a><span class='hs-comment'>-- @</span>
<a name="line-70"></a><span class='hs-comment'>-- `unsetEnv` name</span>
<a name="line-71"></a><span class='hs-comment'>-- @</span>
<a name="line-72"></a><span class='hs-comment'>--</span>
<a name="line-73"></a><span class='hs-comment'>-- If you don't care about Windows support and want to set an environment</span>
<a name="line-74"></a><span class='hs-comment'>-- variable to the empty string use @System.Posix.Env.setEnv@ from the @unix@</span>
<a name="line-75"></a><span class='hs-comment'>-- package instead.</span>
<a name="line-76"></a><span class='hs-comment'>--</span>
<a name="line-77"></a><span class='hs-comment'>-- Throws `Control.Exception.IOException` if @name@ is the empty string or</span>
<a name="line-78"></a><span class='hs-comment'>-- contains an equals sign.</span>
<a name="line-79"></a><span class='hs-comment'>-- </span>
<a name="line-80"></a><span class='hs-comment'>-- Note that setting Unicode values may not work correctly on versions of GHC</span>
<a name="line-81"></a><span class='hs-comment'>-- prior to 7.2.</span>
<a name="line-82"></a><span class='hs-definition'>setEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-83"></a><span class='hs-definition'>setEnv</span> <span class='hs-varid'>key</span> <span class='hs-varid'>value_</span>
<a name="line-84"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>null</span> <span class='hs-varid'>value</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>unsetEnv</span> <span class='hs-varid'>key</span>
<a name="line-85"></a> <span class='hs-keyglyph'>|</span> <span class='hs-varid'>otherwise</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>setEnv_</span> <span class='hs-varid'>key</span> <span class='hs-varid'>value</span>
<a name="line-86"></a> <span class='hs-keyword'>where</span>
<a name="line-87"></a> <span class='hs-comment'>-- NOTE: Anything that follows NUL is ignored on both POSIX and Windows.</span>
<a name="line-88"></a> <span class='hs-comment'>-- We still strip it manually so that the null check above succeds if a</span>
<a name="line-89"></a> <span class='hs-comment'>-- value starts with NUL, and `unsetEnv` is called. This is important for</span>
<a name="line-90"></a> <span class='hs-comment'>-- two reasons.</span>
<a name="line-91"></a> <span class='hs-comment'>--</span>
<a name="line-92"></a> <span class='hs-comment'>-- * On POSIX setting an environment variable to the empty string does not</span>
<a name="line-93"></a> <span class='hs-comment'>-- remove it.</span>
<a name="line-94"></a> <span class='hs-comment'>--</span>
<a name="line-95"></a> <span class='hs-comment'>-- * On Windows setting an environment variable to the empty string</span>
<a name="line-96"></a> <span class='hs-comment'>-- removes that environment variable. A subsequent call to</span>
<a name="line-97"></a> <span class='hs-comment'>-- GetEnvironmentVariable will then return 0, but the calling thread's</span>
<a name="line-98"></a> <span class='hs-comment'>-- last-error code will not be updated, and hence a call to GetLastError</span>
<a name="line-99"></a> <span class='hs-comment'>-- may not return ERROR_ENVVAR_NOT_FOUND. The failed lookup will then</span>
<a name="line-100"></a> <span class='hs-comment'>-- result in a random error instead of the expected</span>
<a name="line-101"></a> <span class='hs-comment'>-- `isDoesNotExistError` (this is at least true for Windows XP, SP 3).</span>
<a name="line-102"></a> <span class='hs-comment'>-- Explicitly calling `unsetEnv` prevents this.</span>
<a name="line-103"></a> <span class='hs-varid'>value</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>takeWhile</span> <span class='hs-layout'>(</span><span class='hs-varop'>/=</span> <span class='hs-chr'>'\NUL'</span><span class='hs-layout'>)</span> <span class='hs-varid'>value_</span>
<a name="line-104"></a>
<a name="line-105"></a><a name="setEnv_"></a><span class='hs-definition'>setEnv_</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-106"></a><span class='hs-cpp'># ifdef mingw32_HOST_OS</span>
<a name="line-107"></a><span class='hs-definition'>setEnv_</span> <span class='hs-varid'>key</span> <span class='hs-varid'>value</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>withCWString</span> <span class='hs-varid'>key</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-varid'>withCWString</span> <span class='hs-varid'>value</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>v</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-108"></a> <span class='hs-varid'>success</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>c_SetEnvironmentVariable</span> <span class='hs-varid'>k</span> <span class='hs-varid'>v</span>
<a name="line-109"></a> <span class='hs-varid'>unless</span> <span class='hs-varid'>success</span> <span class='hs-layout'>(</span><span class='hs-varid'>throwGetLastError</span> <span class='hs-str'>"setEnv"</span><span class='hs-layout'>)</span>
<a name="line-110"></a>
<a name="line-111"></a><span class='hs-keyword'>foreign</span> <span class='hs-keyword'>import</span> <span class='hs-conid'>WINDOWS_CCONV</span> <span class='hs-keyword'>unsafe</span> <span class='hs-str'>"windows.h SetEnvironmentVariableW"</span>
<a name="line-112"></a> <span class='hs-varid'>c_SetEnvironmentVariable</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>LPTSTR</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>LPTSTR</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>Bool</span>
<a name="line-113"></a><span class='hs-cpp'># else</span>
<a name="line-114"></a><span class='hs-definition'>setEnv_</span> <span class='hs-varid'>k</span> <span class='hs-varid'>v</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Posix</span><span class='hs-varop'>.</span><span class='hs-varid'>setEnv</span> <span class='hs-varid'>k</span> <span class='hs-varid'>v</span> <span class='hs-conid'>True</span>
<a name="line-115"></a><span class='hs-cpp'># endif</span>
<a name="line-116"></a>
<a name="line-117"></a><a name="unsetEnv"></a><span class='hs-comment'>-- | @unsetEnv name@ removes the specified environment variable from the</span>
<a name="line-118"></a><span class='hs-comment'>-- environment of the current process.</span>
<a name="line-119"></a><span class='hs-comment'>--</span>
<a name="line-120"></a><span class='hs-comment'>-- Throws `Control.Exception.IOException` if @name@ is the empty string or</span>
<a name="line-121"></a><span class='hs-comment'>-- contains an equals sign.</span>
<a name="line-122"></a><span class='hs-definition'>unsetEnv</span> <span class='hs-keyglyph'>::</span> <span class='hs-conid'>String</span> <span class='hs-keyglyph'>-></span> <span class='hs-conid'>IO</span> <span class='hs-conid'>()</span>
<a name="line-123"></a><span class='hs-cpp'># ifdef mingw32_HOST_OS</span>
<a name="line-124"></a><span class='hs-definition'>unsetEnv</span> <span class='hs-varid'>key</span> <span class='hs-keyglyph'>=</span> <span class='hs-varid'>withCWString</span> <span class='hs-varid'>key</span> <span class='hs-varop'>$</span> <span class='hs-keyglyph'>\</span><span class='hs-varid'>k</span> <span class='hs-keyglyph'>-></span> <span class='hs-keyword'>do</span>
<a name="line-125"></a> <span class='hs-varid'>success</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>c_SetEnvironmentVariable</span> <span class='hs-varid'>k</span> <span class='hs-varid'>nullPtr</span>
<a name="line-126"></a> <span class='hs-varid'>unless</span> <span class='hs-varid'>success</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-127"></a> <span class='hs-comment'>-- We consider unsetting an environment variable that does not exist not as</span>
<a name="line-128"></a> <span class='hs-comment'>-- an error, hence we ignore eRROR_ENVVAR_NOT_FOUND.</span>
<a name="line-129"></a> <span class='hs-varid'>err</span> <span class='hs-keyglyph'><-</span> <span class='hs-varid'>c_GetLastError</span>
<a name="line-130"></a> <span class='hs-varid'>unless</span> <span class='hs-layout'>(</span><span class='hs-varid'>err</span> <span class='hs-varop'>==</span> <span class='hs-varid'>eRROR_ENVVAR_NOT_FOUND</span><span class='hs-layout'>)</span> <span class='hs-varop'>$</span> <span class='hs-keyword'>do</span>
<a name="line-131"></a> <span class='hs-varid'>throwGetLastError</span> <span class='hs-str'>"unsetEnv"</span>
<a name="line-132"></a><span class='hs-cpp'># else</span>
<a name="line-133"></a><span class='hs-definition'>unsetEnv</span> <span class='hs-keyglyph'>=</span> <span class='hs-conid'>Posix</span><span class='hs-varop'>.</span><span class='hs-varid'>unsetEnv</span>
<a name="line-134"></a><span class='hs-cpp'># endif</span>
<a name="line-135"></a><span class='hs-cpp'>#endif</span>
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