minor #23766 Consistently use 7 chars of sha256 for hash-based id generation (nicolas-grekas)

This PR was merged into the 3.4 branch.

Discussion
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Consistently use 7 chars of sha256 for hash-based id generation

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

This prevents generating over long service ids, and for filesystem-related changes, makes the Windows 258 chars limit farther.

Commits
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bc22cdd034 Consistently use 7 chars of sha256 for hash-based id generation

Author: fabpot

Store/FlockStore.php

@@ -71,7 +71,7 @@ private function lock(Key $key, $blocking)
         $fileName = sprintf('%s/sf.%s.%s.lock',
             $this->lockPath,
             preg_replace('/[^a-z0-9\._-]+/i', '-', $key),
-            hash('sha256', $key)
+            strtr(substr(base64_encode(hash('sha256', $key, true)), 0, 7), '/', '_')
         );
 
         // Silence error reporting

Tests/Store/FlockStoreTest.php

@@ -62,8 +62,9 @@ public function testSaveSanitizeName()
         $key = new Key('<?php echo "% hello word ! %" ?>');
 
         $file = sprintf(
-            '%s/sf.-php-echo-hello-word-.4b3d9d0d27ddef3a78a64685dda3a963e478659a9e5240feaf7b4173a8f28d5f.lock',
-            sys_get_temp_dir()
+            '%s/sf.-php-echo-hello-word-.%s.lock',
+            sys_get_temp_dir(),
+            strtr(substr(base64_encode(hash('sha256', $key, true)), 0, 7), '/', '_')
         );
         // ensure the file does not exist before the store
         @unlink($file);