Git pre commit hook written in php that validates the syntax of php files and removes trailing whitespace before commit

cleanup.sed

{
s/[[:space:]]*$//
s/\$Id: .* Exp \$/$Id$/g
}

pre-commit

#!/opt/local/bin/php
<?php
$output = array();
$return = 0;
exec('git rev-parse --verify HEAD 2> /dev/null', $output, $return);
$against = $return == 0 ? 'HEAD' : '4b825dc642cb6eb9a060e54bf8d69288fbee4904';
 
exec("git diff-index --cached --name-only {$against}", $output);
 
$php_pattern = '/(\.(php)|(inc)|(install)|(module))$/';
$cleanup_pattern = '/(\.(css)|(js)|(info)|(txt))$/';
$exit_status = 0;
 
foreach ($output as $file) {
  if (!file_exists($file)) {
    continue;
  }
 
  $is_php = preg_match($php_pattern, $file);
  $may_cleanup = $is_php || preg_match($cleanup_pattern, $file);
 
  if ($may_cleanup) {
    // Perform some cleanup
    exec(sprintf('sed -f ".git/hooks/cleanup.sed" -ie "%s"', $file, $file));
    unlink($file . 'e');
    exec(sprintf('git add "%s"', $file));
  }
 
  if ($is_php) {
    $preg = '/^PHP Parse error:\s+(.+)\s+in\s+(.+)\s+on line\s+(\d+)$/';
    // Check php syntax
    $lint_output = array();
    exec("php -l " . escapeshellarg($file) . ' 2>&1', $lint_output, $return);
    if ($return) {
      foreach ($lint_output as $line) {
        $match = array();
        if (preg_match($preg, $line, $match)) {
          echo "# PHP Parse error:\n# {$match[1]}\n# File: {$match[2]}\n# Line: {$match[3]}\n";
        }
        else {
          echo "# {$line}\n";
        }
      }
      $exit_status = 1;
    }
  }
}
 
exit($exit_status);