Feature: Adds support to check encoding of files

doc/100-General/10-Changelog.md

@@ -21,6 +21,7 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 
 * [#732](https://github.com/Icinga/icinga-powershell-framework/pull/732) Adds support for TLS 1.3 and improves startup response
 * [#735](https://github.com/Icinga/icinga-powershell-framework/pull/735) Adds support to provide occuring problem event id's for the Eventlog and corresponding acknowledgement id's, providing an indicator if certain issues are resolved or still present
+* [#739](https://github.com/Icinga/icinga-powershell-framework/pull/739) Adds support to check the encoding of files to ensure we can properly load them and throw errors for unsupported encoding
 * [#740](https://github.com/Icinga/icinga-powershell-framework/pull/740) Adds new command `Invoke-IcingaForWindowsRESTApi` for easier API communication
 * [#742](https://github.com/Icinga/icinga-powershell-framework/pull/742) Adds support for the CPU provider to limit the CPU usage to 100% for each thread
 

lib/core/installer/tools/Get-FileEncoding.psm1

@@ -0,0 +1,68 @@
+<#
+.SYNOPSIS
+    Determines the encoding of a file.
+
+.DESCRIPTION
+    The Get-FileEncoding function determines the encoding of a file by examining the file's byte order mark (BOM) or by checking if the file is ASCII or UTF8 without BOM.
+
+.PARAMETER Path
+    Specifies the path of the file to check.
+
+.EXAMPLE
+    Get-FileEncoding -Path "C:\path\to\file.txt"
+    Returns the encoding of the specified file.
+
+.OUTPUTS
+    System.String
+    The function returns a string representing the encoding of the file. Possible values are:
+    - UTF8-BOM: UTF-8 encoding with a byte order mark (BOM).
+    - Unicode: UTF-16 encoding (little-endian).
+    - BigEndianUnicode: UTF-16 encoding (big-endian).
+    - UTF7: UTF-7 encoding.
+    - UTF32: UTF-32 encoding.
+    - UTF8: UTF-8 encoding without a byte order mark (BOM).
+    - ASCII: ASCII encoding.
+
+.NOTES
+    This function requires PowerShell version 3.0 or later.
+#>
+
+function Get-FileEncoding()
+{
+    param (
+        [string]$Path = ''
+    );
+
+    if ([string]::IsNullOrEmpty($Path) -Or (Test-Path -Path $Path) -eq $FALSE) {
+        Write-IcingaConsoleError 'The specified file "{0}" was not found' -Objects $Path;
+        return $null;
+    }
+
+    $Bytes = Get-Content -Encoding Byte -ReadCount 4 -TotalCount 4 -Path $Path;
+
+    if ($Bytes[0] -eq 0xef -and $Bytes[1] -eq 0xbb -and $Bytes[2] -eq 0xbf) {
+        return 'UTF8-BOM';
+    } elseif ($Bytes[0] -eq 0xff -and $Bytes[1] -eq 0xfe) {
+        return 'Unicode';
+    } elseif ($Bytes[0] -eq 0xfe -and $Bytes[1] -eq 0xff) {
+        return 'BigEndianUnicode';
+    } elseif ($Bytes[0] -eq 0x2b -and $Bytes[1] -eq 0x2f -and $Bytes[2] -eq 0x76) {
+        return 'UTF7';
+    } elseif ($Bytes[0] -eq 0xff -and $Bytes[1] -eq 0xfe -and $Bytes[2] -eq 0x00 -and $Bytes[3] -eq 0x00) {
+        return 'UTF32';
+    } else {
+        # Check if the file is ASCII or UTF8 without BOM
+        $Content = Get-Content -Encoding String -Path $Path;
+        $Bytes   = [System.Text.Encoding]::UTF8.GetBytes($content);
+
+        # Check each byte to see if it's outside the ASCII range
+        foreach ($byte in $Bytes) {
+            if ($byte -gt 127) {
+                return 'UTF8';
+            }
+        }
+    }
+
+    # This is the default encoding, as UTF8 without BOM could be valid ASCII
+    return 'ASCII';
+}

lib/core/tools/Read-IcingaFileSecure.psm1

@@ -39,9 +39,15 @@ function Read-IcingaFileSecure()
                 [System.IO.FileShare]::Read
             );
 
-            $ReadArray    = New-Object Byte[] $FileStream.Length;
-            $UTF8Encoding = New-Object System.Text.UTF8Encoding $TRUE;
-            $FileContent  = '';
+            $ReadArray     = New-Object Byte[] $FileStream.Length;
+            [bool]$UTF8BOM = $FALSE;
+
+            if ((Get-FileEncoding -Path $File) -eq 'UTF8-BOM') {
+                $UTF8BOM = $TRUE;
+            }
+
+            $UTF8Encoding  = New-Object System.Text.UTF8Encoding $UTF8BOM;
+            $FileContent   = '';
 
             while ($FileStream.Read($ReadArray, 0 , $ReadArray.Length)) {
                 $FileContent = [System.String]::Concat($FileContent, $UTF8Encoding.GetString($ReadArray));