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<h1>Lua-System</h1>
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<li><strong>password_input.lua</strong></li>
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<h2>password_input.lua</h2>
<pre>
<span class="keyword">local</span> sys = <span class="global">require</span> <span class="string">"system"</span>
<span class="global">print</span> <span class="string">[[
This example shows how to disable the "echo" of characters read to the console,
useful for reading secrets from the user.
]]</span>
<span class="comment">--- Function to read from stdin without echoing the input (for secrets etc).
</span><span class="comment">-- It will (in a platform agnostic way) disable echo on the terminal, read the
</span><span class="comment">-- input, and then re-enable echo.
</span><span class="comment">-- @param ... Arguments to pass to <code>io.stdin:read()</code>
</span><span class="comment">-- @return the results of <code>io.stdin:read(...)</code>
</span><span class="keyword">local</span> <span class="keyword">function</span> <span class="function-name">read_secret</span>(...)
<span class="keyword">local</span> w_oldflags, p_oldflags
<span class="keyword">if</span> sys.<span class="function-name">isatty</span>(<span class="global">io</span>.stdin) <span class="keyword">then</span>
<span class="comment">-- backup settings, configure echo flags
</span> w_oldflags = sys.<span class="function-name">getconsoleflags</span>(<span class="global">io</span>.stdin)
p_oldflags = sys.<span class="function-name">tcgetattr</span>(<span class="global">io</span>.stdin)
<span class="comment">-- set echo off to not show password on screen
</span> <span class="global">assert</span>(sys.<span class="function-name">setconsoleflags</span>(<span class="global">io</span>.stdin, w_oldflags - sys.CIF_ECHO_INPUT))
<span class="global">assert</span>(sys.<span class="function-name">tcsetattr</span>(<span class="global">io</span>.stdin, sys.TCSANOW, { lflag = p_oldflags.lflag - sys.L_ECHO }))
<span class="keyword">end</span>
<span class="keyword">local</span> secret, err = <span class="global">io</span>.stdin:<span class="function-name">read</span>(...)
<span class="comment">-- restore settings
</span> <span class="keyword">if</span> sys.<span class="function-name">isatty</span>(<span class="global">io</span>.stdin) <span class="keyword">then</span>
<span class="global">io</span>.stdout:<span class="function-name">write</span>(<span class="string">"\n"</span>) <span class="comment">-- Add newline after reading the password
</span> sys.<span class="function-name">setconsoleflags</span>(<span class="global">io</span>.stdin, w_oldflags)
sys.<span class="function-name">tcsetattr</span>(<span class="global">io</span>.stdin, sys.TCSANOW, p_oldflags)
<span class="keyword">end</span>
<span class="keyword">return</span> secret, err
<span class="keyword">end</span>
<span class="comment">-- Get username
</span><span class="global">io</span>.<span class="function-name">write</span>(<span class="string">"Username: "</span>)
<span class="keyword">local</span> username = <span class="global">io</span>.stdin:<span class="function-name">read</span>(<span class="string">"*l"</span>)
<span class="comment">-- Get the secret
</span><span class="global">io</span>.<span class="function-name">write</span>(<span class="string">"Password: "</span>)
<span class="keyword">local</span> password = <span class="function-name">read_secret</span>(<span class="string">"*l"</span>)
<span class="comment">-- Get domainname
</span><span class="global">io</span>.<span class="function-name">write</span>(<span class="string">"Domain : "</span>)
<span class="keyword">local</span> domain = <span class="global">io</span>.stdin:<span class="function-name">read</span>(<span class="string">"*l"</span>)
<span class="comment">-- Print the results
</span><span class="global">print</span>(<span class="string">""</span>)
<span class="global">print</span>(<span class="string">"Here's what we got:"</span>)
<span class="global">print</span>(<span class="string">" username: "</span> .. username)
<span class="global">print</span>(<span class="string">" password: "</span> .. password)
<span class="global">print</span>(<span class="string">" domain : "</span> .. domain)</pre>
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