fix: stop prompts from asking forever when the input ends

system/CLI/CLI.php

@@ -261,6 +261,10 @@ public static function prompt(string $field, $options = null, $validation = null
 
         if ($validation !== []) {
             while (! static::validate('"' . trim($field) . '"', $input, $validation)) {
+                if (static::$io->isAtEnd()) {
+                    throw CLIException::forInputEnded();
+                }
+
                 $input = static::prompt($field, $options, $validation);
             }
         }
@@ -339,6 +343,11 @@ public static function promptByMultipleKeys(string $text, array $options): array
             }
 
             static::error('Please select correctly.');
+
+            if (static::$io->isAtEnd()) {
+                throw CLIException::forInputEnded();
+            }
+
             CLI::newLine();
         }
     }

system/CLI/Exceptions/CLIException.php

@@ -16,9 +16,6 @@
 use CodeIgniter\Exceptions\DebugTraceableTrait;
 use CodeIgniter\Exceptions\RuntimeException;
 
-/**
- * CLIException
- */
 class CLIException extends RuntimeException
 {
     use DebugTraceableTrait;
@@ -33,4 +30,12 @@ public static function forInvalidColor(string $type, string $color)
     {
         return new static(lang('CLI.invalidColor', [$type, $color]));
     }
+
+    /**
+     * Thrown when a prompt must ask again but the input has ended.
+     */
+    public static function forInputEnded(): static
+    {
+        return new static(lang('CLI.inputEnded'));
+    }
 }

system/CLI/InputOutput.php

@@ -23,6 +23,8 @@ class InputOutput
      */
     private readonly bool $readlineSupport;
 
+    private bool $atEnd = false;
+
     public function __construct()
     {
         // Readline is an extension for PHP that makes interactivity with PHP
@@ -51,7 +53,8 @@ public function input(?string $prefix = null): string
                 self::fwrite(STDOUT, $prefix ?? '');
             }
 
-            $input = readline($prompt);
+            $input       = readline($prompt);
+            $this->atEnd = $input === false && (! defined('STDIN') || ! stream_isatty(STDIN));
 
             return $input === false ? '' : $input;
             // @codeCoverageIgnoreEnd
@@ -60,7 +63,9 @@ public function input(?string $prefix = null): string
         // self:: skips MockInputOutput's fwrite override, whose filter bookkeeping must not nest inside input().
         self::fwrite(STDOUT, $prefix ?? '');
 
-        $input = fgets(fopen('php://stdin', 'rb'));
+        $stdin       = fopen('php://stdin', 'rb');
+        $input       = fgets($stdin);
+        $this->atEnd = $input === false && ! stream_isatty($stdin);
 
         if ($input === false) {
             return '';
@@ -69,6 +74,16 @@ public function input(?string $prefix = null): string
         return $input;
     }
 
+    /**
+     * Whether the last `input()` found the end of an input other than a terminal,
+     * so that no later read can bring an answer. At a terminal, `Ctrl+D` ends only
+     * the current read, and `input()` returns an empty string as for an empty line.
+     */
+    public function isAtEnd(): bool
+    {
+        return $this->atEnd;
+    }
+
     /**
      * While the library is intended for use on CLI commands,
      * commands can be called from controllers and elsewhere

system/Language/en/CLI.php

@@ -53,6 +53,7 @@
     'helpDescription'     => 'Description:',
     'helpOptions'         => 'Options:',
     'helpUsage'           => 'Usage:',
+    'inputEnded'          => 'The input ended before a valid answer was given.',
     'invalidColor'        => 'Invalid "{0}" color: "{1}".',
     'namespaceNotDefined' => 'Namespace "{0}" is not defined.',
     'signals'             => [

system/Test/Mock/MockInputOutput.php

@@ -160,6 +160,14 @@ public function input(?string $prefix = null): string
         return $input;
     }
 
+    /**
+     * Whether the scripted answers have run out, so that a scripted empty answer before the last stays an empty line.
+     */
+    public function isAtEnd(): bool
+    {
+        return $this->inputs === [];
+    }
+
     public function fwrite($handle, string $string): void
     {
         $this->addStreamFilters();

system/Test/PhpStreamWrapper.php

@@ -60,6 +60,14 @@ public function stream_open(): bool
         return true;
     }
 
+    /**
+     * Returns `false`, since the stream has no descriptor.
+     */
+    public function stream_cast(): false
+    {
+        return false;
+    }
+
     /**
      * @return string
      */

tests/system/CLI/CLITest.php

@@ -13,6 +13,7 @@
 
 namespace CodeIgniter\CLI;
 
+use CodeIgniter\CLI\Exceptions\CLIException;
 use CodeIgniter\Config\Services;
 use CodeIgniter\Exceptions\RuntimeException;
 use CodeIgniter\Superglobals;
@@ -448,6 +449,61 @@ public function testPromptByMultipleKeysDefaultsToTheFirstKey(): void
         $this->assertStringNotContainsString('Please select correctly.', $io->getOutput());
     }
 
+    public function testInputReportsTheEndOfTheInput(): void
+    {
+        $io = new InputOutput();
+
+        PhpStreamWrapper::register();
+        PhpStreamWrapper::setContent('red');
+        $io->input();
+        $this->assertFalse($io->isAtEnd());
+
+        PhpStreamWrapper::setContent('');
+        $io->input();
+        $this->assertTrue($io->isAtEnd());
+
+        PhpStreamWrapper::restore();
+    }
+
+    /**
+     * @param list<string>      $inputs
+     * @param callable(): mixed $prompt
+     */
+    #[DataProvider('providePromptsStopAskingWhenTheInputEnds')]
+    public function testPromptsStopAskingWhenTheInputEnds(array $inputs, callable $prompt): void
+    {
+        $io = new MockInputOutput();
+        $io->setInputs($inputs);
+        CLI::setInputOutput($io);
+
+        $this->expectException(CLIException::class);
+        $this->expectExceptionMessage('The input ended before a valid answer was given.');
+
+        $prompt();
+    }
+
+    /**
+     * @return iterable<string, array{list<string>, callable(): mixed}>
+     */
+    public static function providePromptsStopAskingWhenTheInputEnds(): iterable
+    {
+        yield 'prompt' => [[''], static fn (): string => CLI::prompt('Name', null, 'required')];
+
+        yield 'promptByKey' => [['c'], static fn (): string => CLI::promptByKey('Pick:', ['a' => 'Apple', 'b' => 'Banana'], 'in_list[b]')];
+
+        yield 'promptByMultipleKeys' => [['9'], static fn (): array => CLI::promptByMultipleKeys('Pick:', ['a' => 'Apple', 'b' => 'Banana'])];
+    }
+
+    public function testMockInputOutputKeepsAnEmptyAnswerBeforeTheLastAsAnEmptyLine(): void
+    {
+        $io = new MockInputOutput();
+        $io->setInputs(['', 'red']);
+        CLI::setInputOutput($io);
+
+        $this->assertSame('red', CLI::prompt('Color', null, 'required'));
+        $this->assertTrue($io->isAtEnd());
+    }
+
     public function testNewLine(): void
     {
         $this->expectOutputString('');

user_guide_src/source/changelogs/v4.7.6.rst

@@ -18,6 +18,7 @@ BREAKING
 Message Changes
 ***************
 
+- Added the ``CLI.inputEnded`` language string.
 - Added the ``Format.invalidXMLValue`` language string.
 
 *******
@@ -35,6 +36,7 @@ Bugs Fixed
 **********
 
 - **CLI:** Fixed a bug where ``CLI::promptByMultipleKeys()`` accepted a key missing from the options when it was below the last key, returning an empty selection, rejected a key above the last one when the options were not in key order, and offered ``0`` as the default when the first key was not ``0``.
+- **CLI:** Fixed a bug where a prompt asked again forever when its input was piped or redirected and ran out before a valid answer: ``CLI::prompt()`` and ``CLI::promptByKey()`` whose default fails the validation rules, and ``CLI::promptByMultipleKeys()`` whose options have string keys. They now throw a ``CLIException``. The new ``InputOutput::isAtEnd()`` tells that end of the input from an empty line. Pressing Ctrl+D at a terminal still asks again.
 - **Commands:** Fixed a bug where generator commands did not sort the imports of a template with CRLF line endings.
 - **Format:** Fixed ``XMLFormatter`` so that an array key that becomes empty after sanitization no longer triggers a ``ValueError``; the fallback tag name ``item`` is used instead. Values that cannot be converted to a string, such as objects not implementing ``Stringable``, now throw a ``FormatException`` instead of a fatal ``Error``.
 - **Helpers:** Fixed a regression in v4.7.5 where ``set_value()`` threw a ``TypeError`` when the default value was not a string or an array, such as an integer, a float, ``null``, or a ``Stringable`` object. Such values are now converted to a string.