Fail gracefully when the extension required for the compression algor…

…ithm is not loaded (#205)

- Add a warning in the documentation and the logs of the `compile` command regarding the extension required to execute a PHAR once compressed
- Handle the compression in `Box` instead of using the leaked `Box#phar`
- Make `Box` countable
- A few minor refactoring bits

Closes #186

doc/configuration.md

@@ -52,6 +52,7 @@ The configuration file is a JSON object saved to a file. Note that all settings
     "datetime_format": "?",
     "directories": "?",
     "directories-bin": "?",
+    "dump-autoload": "?",
     "files": "?",
     "files-bin": "?",
     "finder": "?",
@@ -140,6 +141,10 @@ If a `composer.json` is found without a `composer.lock`, the it will be taken as
 requirements regardless of whether there is no `composer.lock` because there is no dependencies or because it has been
 removed.
 
+**Warning**: this check is still done within the PHAR. As a result, if [the required extension to open the PHAR][compression]
+due to the compression algorithm is not loaded, a hard failure will still appear: the requirement checker _cannot_ be
+executed before that.
+
 
 ## Including files
 
@@ -510,10 +515,14 @@ The compression (`string`|`null`) setting is the compression algorithm to use wh
 affects the individual files within the PHAR and not the PHAR as a whole ([`Phar::compressFiles()`][phar.compress]). The
 following is a list of the signature algorithms available:
 
-- `BZ2`
 - `GZ` (the most efficient most of the time)
+- `BZ2`
 - `NONE` (default)
 
+**Warning**: be aware that if compressed, the PHAR will required the appropriate extension ([`zlib`][zlib-extension] for
+`GZ` and [`bz2`][bz2-extension] for `BZ2`) to execute the PHAR. Without it, PHP will _not_ be able to open the PHAR at
+all.
+
 
 ## Signing algorithm (`algorithm`)
 
@@ -578,6 +587,8 @@ The metadata (`any`) setting can be any value. This value will be stored as meta
 [composer-bin]: https://getcomposer.org/doc/04-schema.md#bin
 [composer-classmap-authoritative]: https://getcomposer.org/doc/articles/autoloader-optimization.md#optimization-level-2-a-authoritative-class-maps
 [composer-no-dev-option]: https://getcomposer.org/doc/03-cli.md#dump-autoload-dumpautoload-
+[zlib-extension]: https://secure.php.net/manual/en/book.zlib.php
+[bz2-extension]: https://secure.php.net/manual/en/book.bzip2.php
 
 
 //TODO: rework the rest

src/Box.php

@@ -15,18 +15,23 @@
 namespace KevinGH\Box;
 
 use Assert\Assertion;
+use BadMethodCallException;
 use Closure;
+use Countable;
 use KevinGH\Box\Compactor\PhpScoper;
 use KevinGH\Box\Composer\ComposerOrchestrator;
 use KevinGH\Box\PhpScoper\NullScoper;
 use KevinGH\Box\PhpScoper\Scoper;
 use Phar;
 use RecursiveDirectoryIterator;
+use RuntimeException;
 use SplFileInfo;
 use function Amp\ParallelFunctions\parallelMap;
 use function Amp\Promise\wait;
+use function array_flip;
 use function array_map;
 use function chdir;
+use function extension_loaded;
 use function file_exists;
 use function getcwd;
 use function KevinGH\Box\FileSystem\dump_file;
@@ -35,13 +40,14 @@
 use function KevinGH\Box\FileSystem\make_tmp_dir;
 use function KevinGH\Box\FileSystem\mkdir;
 use function KevinGH\Box\FileSystem\remove;
+use function sprintf;
 
 /**
  * Box is a utility class to generate a PHAR.
  *
  * @private
  */
-final class Box
+final class Box implements Countable
 {
     public const DEBUG_DIR = '.box_dump';
 
@@ -154,6 +160,49 @@ public function endBuffering(bool $dumpAutoload): void
         $this->phar->stopBuffering();
     }
 
+    /**
+     * @return null|string The required extension to execute the PHAR now that it is compressed
+     */
+    public function compress(int $compressionAlgorithm): ?string
+    {
+        Assertion::false($this->buffering, 'Cannot compress files while buffering.');
+        Assertion::inArray($compressionAlgorithm, get_phar_compression_algorithms());
+
+        $extensionRequired = get_phar_compression_algorithm_extension($compressionAlgorithm);
+
+        if (null !== $extensionRequired && false === extension_loaded($extensionRequired)) {
+            throw new RuntimeException(
+                sprintf(
+                    'Cannot compress the PHAR with the compression algorithm "%s": the extension "%s" is required but appear to not '
+                    .'be loaded',
+                    array_flip(get_phar_compression_algorithms())[$compressionAlgorithm],
+                    $extensionRequired
+                )
+            );
+        }
+
+        try {
+            if (Phar::NONE === $compressionAlgorithm) {
+                $this->getPhar()->decompressFiles();
+            } else {
+                $this->phar->compressFiles($compressionAlgorithm);
+            }
+        } catch (BadMethodCallException $exception) {
+            $exceptionMessage = 'unable to create temporary file' !== $exception->getMessage()
+                ? 'Could not compress the PHAR: '.$exception->getMessage()
+                : sprintf(
+                    'Could not compress the PHAR: the compression requires too many file descriptors to be opened (%s). Check '
+                    .'your system limits or install the posix extension to allow Box to automatically configure it during the compression',
+                    $this->phar->count()
+                )
+            ;
+
+            throw new RuntimeException($exceptionMessage, $exception->getCode(), $exception);
+        }
+
+        return $extensionRequired;
+    }
+
     /**
      * @param Compactor[] $compactors
      */
@@ -399,4 +448,14 @@ function (string $contents, Compactor $compactor) use ($file): string {
             $contents
         );
     }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function count(): int
+    {
+        Assertion::false($this->buffering, 'Cannot count the number of files in the PHAR when buffering');
+
+        return $this->phar->count();
+    }
 }

src/Composer/ComposerOrchestrator.php

@@ -17,11 +17,11 @@
 use Composer\Factory;
 use Composer\IO\NullIO;
 use Humbug\PhpScoper\Autoload\ScoperAutoloadGenerator;
+use RuntimeException;
+use Throwable;
 use function KevinGH\Box\FileSystem\dump_file;
 use function KevinGH\Box\FileSystem\file_contents;
 use function preg_replace;
-use RuntimeException;
-use Throwable;
 
 /**
  * @private

src/Console/Command/Build.php

@@ -17,8 +17,8 @@
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Style\SymfonyStyle;
-use function trigger_error;
 use const E_USER_DEPRECATED;
+use function trigger_error;
 
 /**
  * @deprecated