run-tests.php: Save STDIN section into a file (#18305)

When a test has an --STDIN-- or --PHPDBG-- section, save the section's content into a file, like we do for the other sections.

This makes it bit easier to reproduce these tests outside of run-tests.php.

This doesn't update the .sh file to pass the file as stdin to the program, yet. 

When using gdb, we can pass the file as stdin like this:

    gdb --args php
    (gdb) r test.php < test.stdin

Author: arnaud-lb

.gitignore

@@ -237,6 +237,7 @@ php
 **/tests/**/*.exp
 **/tests/**/*.log
 **/tests/**/*.sh
+**/tests/**/*.stdin
 
 # Generated by some test cases
 **/tests/**/*.db

run-tests.php

@@ -1934,6 +1934,7 @@ function run_test(string $php, $file, array $env): string
     $diff_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'diff';
     $log_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'log';
     $exp_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'exp';
+    $stdin_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'stdin';
     $output_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'out';
     $memcheck_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'mem';
     $sh_filename = $temp_dir . DIRECTORY_SEPARATOR . $main_file_name . 'sh';
@@ -1972,6 +1973,7 @@ function run_test(string $php, $file, array $env): string
     @unlink($diff_filename);
     @unlink($log_filename);
     @unlink($exp_filename);
+    @unlink($stdin_filename);
     @unlink($output_filename);
     @unlink($memcheck_filename);
     @unlink($sh_filename);
@@ -2696,6 +2698,16 @@ function run_test(string $php, $file, array $env): string
             $diff = generate_diff($wanted, $wanted_re, $output);
         }
 
+        // write .stdin
+        if ($test->hasSection('STDIN') || $test->hasSection('PHPDBG')) {
+            $stdin = $test->hasSection('STDIN')
+                ? $test->getSection('STDIN')
+                : $test->getSection('PHPDBG') . "\n";
+            if (file_put_contents($stdin_filename, $stdin) === false) {
+                error("Cannot create test stdin - $stdin_filename");
+            }
+        }
+
         if (is_array($IN_REDIRECT)) {
             $orig_shortname = str_replace(TEST_PHP_SRCDIR . '/', '', $file);
             $diff = "# original source file: $orig_shortname\n" . $diff;