Added ability to specify compatibility in hotfix

composer.json

@@ -17,6 +17,7 @@
     "require": {
         "symfony/console": "^3.0",
         "symfony/yaml": "^3.0",
-        "noccylabs/downloader": "@dev"
+        "noccylabs/downloader": "@dev",
+        "symfony/expression-language": "^3.2"
     }
 }

docs/EXPRESSIONS.md

@@ -0,0 +1,29 @@
+Matching Expressions
+====================
+
+Hotfixes can provide a `for` key with an array of supported systems. The
+expressions are evaluated using Symfony's ExpressionLanguage and as such
+can handle some pretty complex stuff.
+
+For a hotfix to be considered supported, at least one of the expressions
+must evaluate to true.
+
+
+## Example:
+
+    for:
+        - lsb.id=='raspbian'
+        - lsb.id=='ubuntu' and lsb.release=>'16.04'
+
+
+## System facts
+
+### Distribution
+
+Information is retrieved using `lsb_release` or the `/etc/os-release` file.
+
+      lsb.id            Distribution ID (ex. ubuntu or raspbian)
+      lsb.description   Pretty description
+      lsb.release       Version number (ex. 16.04 or 8)
+      lsb.codename      Release codename (ex. xenial, not always present)
+

src/Command/ApplyCommand.php

@@ -10,7 +10,10 @@ use Symfony\Component\Console\Input\InputOption;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Question\ConfirmationQuestion;
 use Symfony\Component\Console\Question\ChoiceQuestion;
+use Symfony\Component\ExpressionLanguage\ExpressionLanguage;
 use NoccyLabs\Hotfix\Hotfix\Loader;
+use NoccyLabs\Hotfix\System\Facts;
+
 
 class ApplyCommand extends Command
 {
@@ -64,6 +67,28 @@ class ApplyCommand extends Command
         } else {
             $output->writeln("<fg=red;options=bold>Warning: Hotfix is not signed or signature not valid!</fg=red;options=bold>");
         }
+        
+        $requires = $hotfix->getRequirements();
+        if (count($requires)>0) {
+            $engine = new ExpressionLanguage();
+            $facts = Facts::getSystemFacts()->getFacts();
+            while (true) {
+                $expr = array_shift($requires);
+                $ret = $engine->evaluate($expr, $facts);
+                if ($ret) {
+                    //$output->writeln("<fg=green;options=bold>Hotfix is compatible with the current distribution</>");
+                    break;
+                }
+                if (count($requires)==0) {
+                    $output->writeln("<error>Error: This hotfix it not compatible with the current distribution</>");
+                    return false;
+                }
+            }
+        //} else {
+            //$output->writeln("<fg=green;options=bold>Hotfix indicates universal compatibility.</>");
+        }
+
+
         $output->writeln("");
         $output->writeln("  Hotfix:  <fg=yellow;options=bold>".$hotfix->getName()."</fg=yellow;options=bold>");
         $output->writeln("  Author:  <comment>".$hotfix->getAuthor()."</comment>");

src/Hotfix/Hotfix.php

@@ -70,6 +70,14 @@ class Hotfix
         unlink($tmpfile);
     }
 
+    public function getRequirements()
+    {
+        if (!array_key_exists('for',$this->header)) {
+            return [];
+        }
+        return $this->header['for'];
+    }
+
     public function getSignedBy()
     {
         if (!$this->signer) {

src/System/Facts.php

@@ -0,0 +1,51 @@
+<?php
+
+namespace NoccyLabs\Hotfix\System;
+
+use Symfony\Component\Console\Application;
+
+class Facts
+{
+    private $facts;
+
+    public static function getSystemFacts()
+    {
+        static $facts;
+        if (!$facts) {
+            $facts = new self();
+            $facts->read();
+        }
+        return $facts;
+    }
+
+    public function read()
+    {
+        $facts = [];
+        $has_lsb_release = exec("which lsb_release");
+        if ($has_lsb_release) {
+            exec("lsb_release -idrcs", $output);
+            $facts['lsb'] = (object)[
+                'id' => strtolower($output[0]),
+                'description' => $output[1],
+                'release' => $output[2],
+                'codename' => $output[3]
+            ];
+        } elseif (file_exists("/etc/os-release")) {
+            $ini = parse_ini_file("/etc/os-release");
+            $facts['lsb'] = (object)[
+                'id' => strtolower(@$ini['ID']),
+                'description' => @$ini['PRETTY_NAME'],
+                'release' => @$ini['VERSION_ID'],
+                'codename' => @$ini['VERSION_CODENAME']
+            ];
+        }
+        
+        $this->facts = $facts;
+    }
+
+    public function getFacts()
+    {
+        return $this->facts;
+    }
+
+}