Merge pull request #312 from Icinga:fix/negative_values_cause_exception

Fix: Exception on negative offsets

In case negative offsets were processed by the checker handling, in some scenarios this would cause an exception.

Author: LordHepipud

doc/31-Changelog.md

@@ -11,7 +11,11 @@ Released closed milestones can be found on [GitHub](https://github.com/Icinga/ic
 
 [Issue and PRs](https://github.com/Icinga/icinga-powershell-framework/milestone/15?closed=1)
 
-## Enhancements
+### Bugfixes
+
+* [#311](https://github.com/Icinga/icinga-powershell-framework/issues/311) Fixes an issue with negative inputs on some scenarios which will cause an exception for checks instead of continuing executing them properly
+
+### Enhancements
 
 * [#301](https://github.com/Icinga/icinga-powershell-framework/pull/301) Improves error handling to no longer print passwords in case `String` is used for `SecureString` arguments
 * [#305](https://github.com/Icinga/icinga-powershell-framework/pull/305) Adds a new Cmdlet to test if functions with `Add-Type` are already present inside the current scope of the shell

lib/core/tools/Convert-IcingaPluginThresholds.psm1

@@ -103,6 +103,7 @@ function Convert-IcingaPluginThresholds()
 
         [bool]$HasTilde = $FALSE;
         [bool]$HasAt    = $FALSE;
+        [bool]$Negate   = $FALSE;
         $Value          = '';
         $WorkUnit       = '';
 
@@ -114,6 +115,11 @@ function Convert-IcingaPluginThresholds()
             $ThresholdValue = $ThresholdValue.Replace('@', '');
         }
 
+        if ($ThresholdValue[0] -eq '-' -And $ThresholdValue.Length -ge 1) {
+            $Negate         = $TRUE;
+            $ThresholdValue = $ThresholdValue.Substring(1, $ThresholdValue.Length - 1);
+        }
+
         If (($ThresholdValue -Match "(^[\d\.]*) ?(B|KB|MB|GB|TB|PT|KiB|MiB|GiB|TiB|PiB)")) {
             $WorkUnit = 'B';
             if ([string]::IsNullOrEmpty($RetValue.Unit) -eq $FALSE -And $RetValue.Unit -ne $WorkUnit) {
@@ -133,7 +139,7 @@ function Convert-IcingaPluginThresholds()
             $Value         = ([string]$ThresholdValue).Replace(' ', '').Replace('%', '');
             $RetValue.Unit = $WorkUnit;
         } else {
-            # Load all other units/values genericly
+            # Load all other units/values generically
             [string]$StrNumeric = '';
             [bool]$FirstChar    = $TRUE;
             [bool]$Delimiter    = $FALSE;
@@ -161,6 +167,12 @@ function Convert-IcingaPluginThresholds()
             }
         }
 
+        if ((Test-Numeric $Value) -And $Negate) {
+            $Value = $Value * -1;
+        } elseif ($Negate) {
+            $Value = [string]::Format('-{0}', $Value);
+        }
+
         if ($HasTilde) {
             $ConvertedValue += [string]::Format('~{0}', $Value);
         } elseif ($HasAt) {