I'm developing a web page that should read and change the contents of specific files on the server.
These files will only have two values: 1 or 0. Reading/changing the contents will be made via combo boxes with OnChange. Basically the idea is to control appliances via General Purpose Input/Outputs (GPIO's). The electronics part is all done, I just need to finish the web programing part and got stuck on it.
I'm not experienced in programing at all, but with some snippets found here and there, I was able to implement part of it with AJAX/PHP.
So far, I'm able to read the values, but unable to change it even though I'm building the correct command with "escapeshellarg".
Also, I was expecting to have two interactive areas in the page but only the original is working.
Could anyone point me into the right direction? Any help/suggestion/comment will be welcomed.
pqp6.php
<html>
<head>
<script>
function showUser(str)
{
if (str=="")
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","getinfo.php?q="+str,true);
xmlhttp.send();
}
</script>
</head>
<body>
<?php
$file1="/var/www/file1";
$file2="/var/www/file2";
$output = shell_exec('cat '.escapeshellarg($file1));
if($output == 0)
{
echo "zero ; ";
$file1status = "off";
$file1oposite = "on";
$file1exec= "file1on";
}
else
{
echo "one ; ";
$file1status= "on";
$file1oposite= "off";
$file1exec= "file1off";
}
echo "output:$output ; file1status:$file1status ; file1oposite:$file1oposite ; file1exec:$file1exec <br><br>";
$output = shell_exec('cat '.escapeshellarg($file2));
if($output == 0)
{
echo "zero ; ";
$file2status = "off";
$file2oposite = "on";
$file2exec= "file2on";
}
else
{
echo "one ; ";
$file2status= "on";
$file2oposite= "off";
$file2exec= "file2off";
}
echo "output:$output ; file2status:$file2status ; file2oposite:$file2oposite ; file2exec:$file2exec <br><br>";
?>
<br>
<br>
FILE 1:
<form>
<select name="file1" onchange="showUser(this.value)">
<option value="1,<?=$file1status?>"><?=$file1status?></option>
<option value="1,<?=$file1oposite?>"><?=$file1oposite?></option>
</select>
</form>
<br>
<div id="txtHint"><b>File 1 information will be listed here.</b> </div>
<br>
<br>
FILE 2:
<form>
<select name="file2" onchange="showUser(this.value)">
<option value="2,<?=$file2status?>"><?=$file2status?></option>
<option value="2,<?=$file2oposite?>"><?=$file2oposite?></option>
</select>
</form>
<br>
<div id="txtHint"><b>File 2 information will be listed here.</b></div>
</body>
</html>
getinfo.php:
<?php
$q=$_GET["q"];
$q_stripped = explode(",", $q);
$file_n = $q_stripped[0];
$file_command = $q_stripped[1];
$path="/var/www/file";
if($file_command == "on")
{
$file_command = "1 > ";
}
else
{
$file_command = "0 > ";
}
$command= "/bin/echo $file_command$path$file_n";
$escaped_command = escapeshellarg($command);
echo "COMMAND: $escaped_command";
shell_exec($escaped_command);
echo "file_n=$file_n ; file_command=$file_command ; ";
?><?php
By applying the escapeshellcmd your > 0 or > 1 is turned into \\> 0 and \\> 1 I guess that is why it doesnt work. You are not using escapeshellcmd, you are using escapeshellarg.
You might want to check the file permissions also.
However, instead of using system calls, have you ever thought about using file_exists, file_get_contents or file_put_contents .
With those functions and writable dirs/files, you can achieve exactly what you are doing, without making system calls. Plus, it would be more portable.