[BUGFIX] Handle excess whitespace characters in `CommandUtility::exec()`

PHP's behavior of `exec()` [1] is flabbergasting: when writing the
buffer, trailing whitespace characters are trimmed as follows:

1. the last PHP_EOL character is chopped
2. any left-over trailing literal space characters are trimmed

Neither of this was handled in the implementation introduced
in #104045, leading to unexpected output.

This commit emulates the behavior of PHP's internal `exec()` function,
restoring the previous behavior of `CommandUtility::exec()`.

[1] https://github.com/php/php-src/blob/master/ext/standard/exec.c

Resolves: #105251
Related: #104045
Releases: main
Change-Id: I726b6ac0214f2cb3983db7b66c366a1fa58f93f8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/86533


Reviewed-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Kott <benjamin.kott@outlook.com>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Tested-by: core-ci <typo3@b13.com>
Reviewed-by: Andreas Kienast <akienast@scripting-base.de>
Tested-by: Andreas Kienast <akienast@scripting-base.de>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>

typo3/sysext/core/Classes/Utility/CommandUtility.php

@@ -108,9 +108,15 @@ class CommandUtility
             return false;
         }
 
-        $output = explode(PHP_EOL, $process->getOutput());
+        $processOutput = $process->getOutput();
+        if (str_ends_with($processOutput, PHP_EOL)) {
+            // Last \n is ignored by PHP exec(): https://github.com/php/php-src/blob/b675db4c56dd0de4ea1f5195d587ed90f0096ed8/ext/standard/exec.c#L148
+            $processOutput = substr($processOutput, 0, -1);
+        }
+        $output = explode(PHP_EOL, $processOutput);
+
+        return rtrim(strrchr($processOutput, PHP_EOL) ?: $processOutput);
 
-        return $output[count($output) - 1] ?? '';
     }
 
     /**