Add --absolute to resolve absolute paths in config command, otherwise set default back to relative

doc/03-cli.md

@@ -397,16 +397,18 @@ options.
 ### Options
 
 * **--global (-g):** Operate on the global config file located at
-`$COMPOSER_HOME/config.json` by default.  Without this option, this command
-affects the local composer.json file or a file specified by `--file`.
+  `$COMPOSER_HOME/config.json` by default.  Without this option, this command
+  affects the local composer.json file or a file specified by `--file`.
 * **--editor (-e):** Open the local composer.json file using in a text editor as
-defined by the `EDITOR` env variable.  With the `--global` option, this opens
-the global config file.
+  defined by the `EDITOR` env variable.  With the `--global` option, this opens
+  the global config file.
 * **--unset:** Remove the configuration element named by `setting-key`.
 * **--list (-l):** Show the list of current config variables.  With the `--global`
- option this lists the global configuration only.
+  option this lists the global configuration only.
 * **--file="..." (-f):** Operate on a specific file instead of composer.json. Note
- that this cannot be used in conjunction with the `--global` option.
+  that this cannot be used in conjunction with the `--global` option.
+* **--absolute:** Returns absolute paths when fetching *-dir config values
+  instead of relative.
 
 ### Modifying Repositories
 

src/Composer/Command/ConfigCommand.php

@@ -57,6 +57,7 @@ class ConfigCommand extends Command
                 new InputOption('unset', null, InputOption::VALUE_NONE, 'Unset the given setting-key'),
                 new InputOption('list', 'l', InputOption::VALUE_NONE, 'List configuration settings'),
                 new InputOption('file', 'f', InputOption::VALUE_REQUIRED, 'If you want to choose a different composer.json or config.json', 'composer.json'),
+                new InputOption('absolute', null, InputOption::VALUE_NONE, 'Returns absolute paths when fetching *-dir config values instead of relative'),
                 new InputArgument('setting-key', null, 'Setting key'),
                 new InputArgument('setting-value', InputArgument::IS_ARRAY, 'Setting value'),
             ))
@@ -218,7 +219,7 @@ EOT
 
                 $value = $data;
             } elseif (isset($data['config'][$settingKey])) {
-                $value = $data['config'][$settingKey];
+                $value = $this->config->get($settingKey, $input->getOption('absolute') ? 0 : Config::RELATIVE_PATHS);
             } else {
                 throw new \RuntimeException($settingKey.' is not defined');
             }

src/Composer/Config.php

@@ -19,6 +19,8 @@ use Composer\Config\ConfigSourceInterface;
  */
 class Config
 {
+    const RELATIVE_PATHS = 1;
+
     public static $defaultConfig = array(
         'process-timeout' => 300,
         'use-include-path' => false,
@@ -153,7 +155,7 @@ class Config
      * @throws \RuntimeException
      * @return mixed
      */
-    public function get($key)
+    public function get($key, $flags = 0)
     {
         switch ($key) {
             case 'vendor-dir':
@@ -169,7 +171,7 @@ class Config
                 $val = rtrim($this->process($this->getComposerEnv($env) ?: $this->config[$key]), '/\\');
                 $val = preg_replace('#^(\$HOME|~)(/|$)#', rtrim(getenv('HOME') ?: getenv('USERPROFILE'), '/\\') . '/', $val);
 
-                return $this->realpath($val);
+                return ($flags & self::RELATIVE_PATHS == 1) ? $val : $this->realpath($val);
 
             case 'cache-ttl':
                 return (int) $this->config[$key];