Logging: Implement "search within log files" (#41353)

* Normalize render method names

* Refactor get_query_params to allow key filtering

* Scaffold the search results view

* Add missing unslash

* First pass at functional search

* Fix memory leak and recursive highlighting

* Fix various search string edge cases

* Move match highlighting to format_match method

* Tweak match line formatting

* Rename ListTable to FileListTable

* Switch search results view to a list table

* Add notice about max files for search

* Remove unused function

* Only use monospace font on the matched line part of search results

* Add notice about search result limit

* Fix font in table header

* phpcs cleanup

* Remove unnecessary search form action

* Add caching to search results

* Add unit test for search method

* Caching improvements

* phpcs cleanup

* Add unit test for close_stream

* Remove unneeded linting exception

* Add changelog file

* Remove unnecessary usage of get_class()

* Make sure file stream gets closed when we break the loop early

* Make the returned results an even 200 when hitting the limit

plugins/woocommerce/changelog/try-log-search

@@ -0,0 +1,4 @@
+Significance: minor
+Type: add
+
+Adds a search field to the log files list table screen that will do a partial match string search on the contents of all the files currently shown in the list table

plugins/woocommerce/client/legacy/css/admin.scss

@@ -1351,9 +1351,35 @@ table.wc_status_table--tools {
 .wc-logs-single-file-actions {
 	margin-left: auto;
 	display: flex;
+	flex-flow: row wrap;
 	gap: 0.5em;
 }
 
+.wc-logs-search {
+	margin-left: auto;
+	display: flex;
+	flex-flow: column;
+}
+
+.wc-logs-search-fieldset {
+	display: flex;
+	gap: 0.5em;
+	justify-content: flex-end;
+}
+
+.wc-logs-search-notice {
+	font-size: 0.9em;
+	line-height: 2;
+	text-align: right;
+	visibility: hidden;
+	height: 0;
+
+	.wc-logs-search:focus-within & {
+		visibility: visible;
+		height: auto;
+	}
+}
+
 .wc-logs-entries {
 	background: #f6f7f7;
 	border: 1px solid #c3c4c7;
@@ -1418,6 +1444,44 @@ table.wc_status_table--tools {
 	}
 }
 
+.wc-logs-search-results {
+	tbody {
+		word-wrap: break-word;
+
+		.column-file_id {
+			line-height: 2;
+		}
+
+		.column-line_number,
+		.column-line {
+			line-height: 2.3;
+		}
+
+		.column-line {
+			font-family: Consolas, Monaco, monospace;
+		}
+	}
+
+	td {
+		vertical-align: middle;
+	}
+
+	.column-file_id {
+		width: 16%;
+	}
+
+	.column-line_number {
+		width: 8%;
+	}
+
+	.search-match {
+		background: #fff8c5;
+		padding: 0.46em 0;
+		border: 1px dashed #c3c4c7;
+		line-height: 2.3;
+	}
+}
+
 /**
  * Log severity level colors.
  *

plugins/woocommerce/includes/admin/class-wc-admin-menus.php

@@ -12,7 +12,7 @@ use Automattic\WooCommerce\Internal\Admin\Marketplace;
 use Automattic\WooCommerce\Internal\Admin\Orders\COTRedirectionController;
 use Automattic\WooCommerce\Internal\Admin\Orders\PageController as Custom_Orders_PageController;
 use Automattic\WooCommerce\Internal\Admin\Logging\PageController as LoggingPageController;
-use Automattic\WooCommerce\Internal\Admin\Logging\FileV2\ListTable as LoggingListTable;
+use Automattic\WooCommerce\Internal\Admin\Logging\FileV2\{ FileListTable, SearchListTable };
 use Automattic\WooCommerce\Internal\Admin\WCAdminAssets;
 use Automattic\WooCommerce\Internal\DataStores\Orders\CustomOrdersTableController;
 use Automattic\WooCommerce\Utilities\FeaturesUtil;
@@ -324,7 +324,8 @@ class WC_Admin_Menus {
 		$screen_options = array(
 			'woocommerce_keys_per_page',
 			'woocommerce_webhooks_per_page',
-			LoggingListTable::PER_PAGE_USER_OPTION_KEY,
+			FileListTable::PER_PAGE_USER_OPTION_KEY,
+			SearchListTable::PER_PAGE_USER_OPTION_KEY,
 		);
 
 		if ( in_array( $option, $screen_options, true ) ) {

plugins/woocommerce/src/Internal/Admin/Logging/FileV2/File.php

@@ -153,7 +153,7 @@ class File {
 	}
 
 	/**
-	 * Open a read-only stream file this file.
+	 * Open a read-only stream for this file.
 	 *
 	 * @return resource|false
 	 */
@@ -166,6 +166,19 @@ class File {
 		return $this->stream;
 	}
 
+	/**
+	 * Close the stream for this file.
+	 *
+	 * The stream will also close automatically when the class instance destructs, but this can be useful for
+	 * avoiding having a large number of streams open simultaneously.
+	 *
+	 * @return bool
+	 */
+	public function close_stream(): bool {
+		// phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_read_fclose -- No suitable alternative.
+		return fclose( $this->stream );
+	}
+
 	/**
 	 * Get the name of the file, with extension, but without full path.
 	 *

plugins/woocommerce/src/Internal/Admin/Logging/FileV2/FileController.php

@@ -4,6 +4,7 @@ declare( strict_types = 1 );
 namespace Automattic\WooCommerce\Internal\Admin\Logging\FileV2;
 
 use Automattic\Jetpack\Constants;
+use WC_Cache_Helper;
 use WP_Error;
 
 /**
@@ -23,6 +24,44 @@ class FileController {
 		'source'   => '',
 	);
 
+	/**
+	 * Default values for arguments for the search_within_files method.
+	 *
+	 * @const array
+	 */
+	public const DEFAULTS_SEARCH_WITHIN_FILES = array(
+		'offset'   => 0,
+		'per_page' => 50,
+	);
+
+	/**
+	 * The maximum number of files that can be searched at one time.
+	 *
+	 * @const int
+	 */
+	public const SEARCH_MAX_FILES = 100;
+
+	/**
+	 * The maximum number of search results that can be returned at one time.
+	 *
+	 * @const int
+	 */
+	public const SEARCH_MAX_RESULTS = 200;
+
+	/**
+	 * The cache group name to use for caching operations.
+	 *
+	 * @const string
+	 */
+	private const CACHE_GROUP = 'log-files';
+
+	/**
+	 * A cache key for storing and retrieving the results of the last logs search.
+	 *
+	 * @const string
+	 */
+	private const SEARCH_CACHE_KEY = 'logs_previous_search';
+
 	/**
 	 * The absolute path to the log directory.
 	 *
@@ -299,9 +338,114 @@ class FileController {
 			}
 		}
 
+		if ( $deleted > 0 ) {
+			$this->invalidate_cache();
+		}
+
 		return $deleted;
 	}
 
+	/**
+	 * Search within a set of log files for a particular string.
+	 *
+	 * @param string $search     The string to search for.
+	 * @param array  $args       Optional. Arguments for pagination of search results.
+	 * @param array  $file_args  Optional. Arguments to filter and sort the files that are returned. See get_files().
+	 * @param bool   $count_only Optional. True to return a total count of the matches.
+	 *
+	 * @return array|int|WP_Error When matches are found, each array item is an associative array that includes the
+	 *                            file ID, line number, and the matched string with HTML markup around the matched parts.
+	 */
+	public function search_within_files( string $search, array $args = array(), array $file_args = array(), bool $count_only = false ) {
+		if ( '' === $search ) {
+			return array();
+		}
+
+		$search = esc_html( $search );
+
+		$args = wp_parse_args( $args, self::DEFAULTS_SEARCH_WITHIN_FILES );
+
+		$file_args = array_merge(
+			$file_args,
+			array(
+				'offset'   => 0,
+				'per_page' => self::SEARCH_MAX_FILES,
+			)
+		);
+
+		$cache_key = WC_Cache_Helper::get_prefixed_key( self::SEARCH_CACHE_KEY, self::CACHE_GROUP );
+		$query     = wp_json_encode( array( $search, $args, $file_args ) );
+		$cache     = wp_cache_get( $cache_key );
+		$is_cached = isset( $cache['query'], $cache['results'] ) && $query === $cache['query'];
+
+		if ( true === $is_cached ) {
+			$matched_lines = $cache['results'];
+		} else {
+			$files = $this->get_files( $file_args );
+			if ( is_wp_error( $files ) ) {
+				return $files;
+			}
+
+			// Max string size * SEARCH_MAX_RESULTS = ~1MB largest possible cache entry.
+			$max_string_size = 5 * KB_IN_BYTES;
+
+			$matched_lines = array();
+
+			foreach ( $files as $file ) {
+				$stream      = $file->get_stream();
+				$line_number = 1;
+
+				while ( ! feof( $stream ) ) {
+					$line = fgets( $stream, $max_string_size );
+					if ( ! is_string( $line ) ) {
+						continue;
+					}
+
+					$sanitized_line = esc_html( trim( $line ) );
+					if ( false !== stripos( $sanitized_line, $search ) ) {
+						$matched_lines[] = array(
+							'file_id'     => $file->get_file_id(),
+							'line_number' => $line_number,
+							'line'        => $sanitized_line,
+						);
+					}
+
+					if ( count( $matched_lines ) >= self::SEARCH_MAX_RESULTS ) {
+						$file->close_stream();
+						break 2;
+					}
+
+					if ( false !== strstr( $line, PHP_EOL ) ) {
+						$line_number ++;
+					}
+				}
+
+				$file->close_stream();
+			}
+
+			$to_cache = array(
+				'query'   => $query,
+				'results' => $matched_lines,
+			);
+			wp_cache_set( $cache_key, $to_cache, self::CACHE_GROUP, DAY_IN_SECONDS );
+		}
+
+		if ( true === $count_only ) {
+			return count( $matched_lines );
+		}
+
+		return array_slice( $matched_lines, $args['offset'], $args['per_page'] );
+	}
+
+	/**
+	 * Invalidate the cache group related to log file data.
+	 *
+	 * @return bool True on successfully invalidating the cache.
+	 */
+	public function invalidate_cache(): bool {
+		return WC_Cache_Helper::invalidate_cache_group( self::CACHE_GROUP );
+	}
+
 	/**
 	 * Sanitize the source property of a log file.
 	 *

plugins/woocommerce/src/Internal/Admin/Logging/FileV2/FileListTable.php

@@ -8,9 +8,9 @@ use Automattic\WooCommerce\Internal\Admin\Logging\PageController;
 use WP_List_Table;
 
 /**
- * ListTable class.
+ * FileListTable class.
  */
-class ListTable extends WP_List_Table {
+class FileListTable extends WP_List_Table {
 	/**
 	 * The user option key for saving the preferred number of files displayed per page.
 	 *
@@ -33,7 +33,7 @@ class ListTable extends WP_List_Table {
 	private $page_controller;
 
 	/**
-	 * ListTable class.
+	 * FileListTable class.
 	 *
 	 * @param FileController $file_controller Instance of FileController.
 	 * @param PageController $page_controller Instance of PageController.
@@ -150,14 +150,17 @@ class ListTable extends WP_List_Table {
 	public function prepare_items(): void {
 		$per_page = $this->get_items_per_page(
 			self::PER_PAGE_USER_OPTION_KEY,
-			$this->file_controller::DEFAULTS_GET_FILES['per_page']
+			$this->get_per_page_default()
 		);
 
 		$defaults  = array(
 			'per_page' => $per_page,
 			'offset'   => ( $this->get_pagenum() - 1 ) * $per_page,
 		);
-		$file_args = wp_parse_args( $this->page_controller->get_query_params(), $defaults );
+		$file_args = wp_parse_args(
+			$this->page_controller->get_query_params( array( 'order', 'orderby', 'source' ) ),
+			$defaults
+		);
 
 		$total_items = $this->file_controller->get_files( $file_args, true );
 		if ( is_wp_error( $total_items ) ) {
@@ -318,4 +321,13 @@ class ListTable extends WP_List_Table {
 
 		return size_format( $size );
 	}
+
+	/**
+	 * Helper to get the default value for the per_page arg.
+	 *
+	 * @return int
+	 */
+	public function get_per_page_default(): int {
+		return $this->file_controller::DEFAULTS_GET_FILES['per_page'];
+	}
 }

plugins/woocommerce/src/Internal/Admin/Logging/FileV2/SearchListTable.php

@@ -0,0 +1,227 @@
+<?php
+declare( strict_types = 1 );
+
+namespace Automattic\WooCommerce\Internal\Admin\Logging\FileV2;
+
+use Automattic\WooCommerce\Internal\Admin\Logging\PageController;
+
+use WP_List_Table;
+
+/**
+ * SearchListTable class.
+ */
+class SearchListTable extends WP_List_Table {
+	/**
+	 * The user option key for saving the preferred number of search results displayed per page.
+	 *
+	 * @const string
+	 */
+	public const PER_PAGE_USER_OPTION_KEY = 'woocommerce_logging_search_results_per_page';
+
+	/**
+	 * Instance of FileController.
+	 *
+	 * @var FileController
+	 */
+	private $file_controller;
+
+	/**
+	 * Instance of PageController.
+	 *
+	 * @var PageController
+	 */
+	private $page_controller;
+
+	/**
+	 * SearchListTable class.
+	 *
+	 * @param FileController $file_controller Instance of FileController.
+	 * @param PageController $page_controller Instance of PageController.
+	 */
+	public function __construct( FileController $file_controller, PageController $page_controller ) {
+		$this->file_controller = $file_controller;
+		$this->page_controller = $page_controller;
+
+		parent::__construct(
+			array(
+				'singular' => 'wc-logs-search-result',
+				'plural'   => 'wc-logs-search-results',
+				'ajax'     => false,
+			)
+		);
+	}
+
+	/**
+	 * Render message when there are no items.
+	 *
+	 * @return void
+	 */
+	public function no_items(): void {
+		esc_html_e( 'No search results.', 'woocommerce' );
+	}
+
+	/**
+	 * Set up the column header info.
+	 *
+	 * @return void
+	 */
+	public function prepare_column_headers(): void {
+		$this->_column_headers = array(
+			$this->get_columns(),
+			array(),
+			array(),
+			$this->get_primary_column(),
+		);
+	}
+
+	/**
+	 * Prepares the list of items for displaying.
+	 *
+	 * @return void
+	 */
+	public function prepare_items(): void {
+		$per_page = $this->get_items_per_page(
+			self::PER_PAGE_USER_OPTION_KEY,
+			$this->get_per_page_default()
+		);
+
+		$args = array(
+			'per_page' => $per_page,
+			'offset'   => ( $this->get_pagenum() - 1 ) * $per_page,
+		);
+
+		$file_args = $this->page_controller->get_query_params( array( 'order', 'orderby', 'search', 'source' ) );
+		$search    = $file_args['search'];
+		unset( $file_args['search'] );
+
+		$total_items = $this->file_controller->search_within_files( $search, $args, $file_args, true );
+		if ( is_wp_error( $total_items ) ) {
+			printf(
+				'<div class="notice notice-warning"><p>%s</p></div>',
+				esc_html( $total_items->get_error_message() )
+			);
+
+			return;
+		}
+
+		if ( $total_items >= $this->file_controller::SEARCH_MAX_RESULTS ) {
+			printf(
+				'<div class="notice notice-info"><p>%s</p></div>',
+				sprintf(
+					// translators: %s is a number.
+					esc_html__( 'The number of search results has reached the limit of %s. Try refining your search.', 'woocommerce' ),
+					esc_html( number_format_i18n( $this->file_controller::SEARCH_MAX_RESULTS ) )
+				)
+			);
+		}
+
+		$total_pages = ceil( $total_items / $per_page );
+		$results     = $this->file_controller->search_within_files( $search, $args, $file_args );
+		$this->items = $results;
+
+		$this->set_pagination_args(
+			array(
+				'per_page'    => $per_page,
+				'total_items' => $total_items,
+				'total_pages' => $total_pages,
+			)
+		);
+	}
+
+	/**
+	 * Gets a list of columns.
+	 *
+	 * @return array
+	 */
+	public function get_columns(): array {
+		$columns = array(
+			'file_id'     => esc_html__( 'File', 'woocommerce' ),
+			'line_number' => esc_html__( 'Line #', 'woocommerce' ),
+			'line'        => esc_html__( 'Matched Line', 'woocommerce' ),
+		);
+
+		return $columns;
+	}
+
+	/**
+	 * Render the file_id column.
+	 *
+	 * @param array $item The current search result being rendered.
+	 *
+	 * @return string
+	 */
+	public function column_file_id( array $item ): string {
+		// Add a word break after the rotation number, if it exists.
+		$file_id = preg_replace( '/\.([0-9])+\-/', '.\1<wbr>-', $item['file_id'] );
+
+		return wp_kses( $file_id, array( 'wbr' => array() ) );
+	}
+
+	/**
+	 * Render the line_number column.
+	 *
+	 * @param array $item The current search result being rendered.
+	 *
+	 * @return string
+	 */
+	public function column_line_number( array $item ): string {
+		$match_url = add_query_arg(
+			array(
+				'view'    => 'single_file',
+				'file_id' => $item['file_id'],
+			),
+			$this->page_controller->get_logs_tab_url() . '#L' . absint( $item['line_number'] )
+		);
+
+		return sprintf(
+			'<a href="%1$s">%2$s</a>',
+			esc_url( $match_url ),
+			sprintf(
+				// translators: %s is a line number in a file.
+				esc_html__( 'Line %s', 'woocommerce' ),
+				number_format_i18n( absint( $item['line_number'] ) )
+			)
+		);
+	}
+
+	/**
+	 * Render the line column.
+	 *
+	 * @param array $item The current search result being rendered.
+	 *
+	 * @return string
+	 */
+	public function column_line( array $item ): string {
+		$params = $this->page_controller->get_query_params( array( 'search' ) );
+		$line   = $item['line'];
+
+		// Highlight matches within the line.
+		$pattern = preg_quote( $params['search'], '/' );
+		preg_match_all( "/$pattern/i", $line, $matches, PREG_OFFSET_CAPTURE );
+		if ( is_array( $matches[0] ) && count( $matches[0] ) >= 1 ) {
+			$length_change = 0;
+
+			foreach ( $matches[0] as $match ) {
+				$replace        = '<span class="search-match">' . $match[0] . '</span>';
+				$offset         = $match[1] + $length_change;
+				$orig_length    = strlen( $match[0] );
+				$replace_length = strlen( $replace );
+
+				$line = substr_replace( $line, $replace, $offset, $orig_length );
+
+				$length_change += $replace_length - $orig_length;
+			}
+		}
+
+		return wp_kses_post( $line );
+	}
+
+	/**
+	 * Helper to get the default value for the per_page arg.
+	 *
+	 * @return int
+	 */
+	public function get_per_page_default(): int {
+		return $this->file_controller::DEFAULTS_SEARCH_WITHIN_FILES['per_page'];
+	}
+}

plugins/woocommerce/src/Internal/Admin/Logging/LogHandlerFileV2.php

@@ -2,9 +2,36 @@
 
 namespace Automattic\WooCommerce\Internal\Admin\Logging;
 
+use Automattic\WooCommerce\Internal\Admin\Logging\FileV2\FileController;
 use WC_Log_Handler_File;
 
 /**
  * LogHandlerFileV2 class.
  */
-class LogHandlerFileV2 extends WC_Log_Handler_File {}
+class LogHandlerFileV2 extends WC_Log_Handler_File {
+	/**
+	 * Handle a log entry.
+	 *
+	 * @param int    $timestamp Log timestamp.
+	 * @param string $level emergency|alert|critical|error|warning|notice|info|debug.
+	 * @param string $message Log message.
+	 * @param array  $context {
+	 *      Additional information for log handlers.
+	 *
+	 *     @type string $source Optional. Determines log file to write to. Default 'log'.
+	 *     @type bool $_legacy Optional. Default false. True to use outdated log format
+	 *         originally used in deprecated WC_Logger::add calls.
+	 * }
+	 *
+	 * @return bool False if value was not handled and true if value was handled.
+	 */
+	public function handle( $timestamp, $level, $message, $context ) {
+		$written = parent::handle( $timestamp, $level, $message, $context );
+
+		if ( $written ) {
+			wc_get_container()->get( FileController::class )->invalidate_cache();
+		}
+
+		return $written;
+	}
+}

plugins/woocommerce/src/Internal/Admin/Logging/PageController.php

@@ -4,9 +4,10 @@ declare( strict_types = 1 );
 namespace Automattic\WooCommerce\Internal\Admin\Logging;
 
 use Automattic\Jetpack\Constants;
-use Automattic\WooCommerce\Internal\Admin\Logging\FileV2\{ FileController, ListTable };
+use Automattic\WooCommerce\Internal\Admin\Logging\FileV2\{ FileController, FileListTable, SearchListTable };
 use Automattic\WooCommerce\Internal\Traits\AccessiblePrivateMethods;
 use WC_Admin_Status;
+use WP_List_Table;
 use WC_Log_Levels;
 
 /**
@@ -24,9 +25,9 @@ class PageController {
 	private $file_controller;
 
 	/**
-	 * Instance of ListTable.
+	 * Instance of FileListTable or SearchListTable.
 	 *
-	 * @var ListTable
+	 * @var FileListTable|SearchListTable
 	 */
 	private $list_table;
 
@@ -97,8 +98,7 @@ class PageController {
 
 		switch ( $handler ) {
 			case LogHandlerFileV2::class:
-				$params = $this->get_query_params();
-				$this->render_filev2( $params );
+				$this->render_filev2();
 				break;
 			case 'WC_Log_Handler_DB':
 				WC_Admin_Status::status_logs_db();
@@ -112,20 +112,21 @@ class PageController {
 	/**
 	 * Render the views for the FileV2 log handler.
 	 *
-	 * @param array $params Args for rendering the views.
-	 *
 	 * @return void
 	 */
-	private function render_filev2( array $params = array() ): void {
-		$view = $params['view'] ?? '';
+	private function render_filev2(): void {
+		$params = $this->get_query_params( array( 'view' ) );
 
-		switch ( $view ) {
+		switch ( $params['view'] ) {
 			case 'list_files':
 			default:
-				$this->render_file_list_page( $params );
+				$this->render_list_files_view();
+				break;
+			case 'search_results':
+				$this->render_search_results_view();
 				break;
 			case 'single_file':
-				$this->render_single_file_page( $params );
+				$this->render_single_file_view();
 				break;
 		}
 	}
@@ -133,18 +134,21 @@ class PageController {
 	/**
 	 * Render the file list view.
 	 *
-	 * @param array $params Args for rendering the view.
-	 *
 	 * @return void
 	 */
-	private function render_file_list_page( array $params = array() ): void {
-		$defaults = $this->get_query_param_defaults();
+	private function render_list_files_view(): void {
+		$params     = $this->get_query_params( array( 'order', 'orderby', 'source', 'view' ) );
+		$defaults   = $this->get_query_param_defaults();
+		$list_table = $this->get_list_table( $params['view'] );
+
+		$list_table->prepare_items();
 
 		?>
 		<header id="logs-header" class="wc-logs-header">
 			<h2>
 				<?php esc_html_e( 'Browse log files', 'woocommerce' ); ?>
 			</h2>
+			<?php $this->render_search_field(); ?>
 		</header>
 		<form id="logs-list-table-form" method="get">
 			<input type="hidden" name="page" value="wc-status" />
@@ -158,8 +162,7 @@ class PageController {
 					/>
 				<?php endif; ?>
 			<?php endforeach; ?>
-			<?php $this->get_list_table()->prepare_items(); ?>
-			<?php $this->get_list_table()->display(); ?>
+			<?php $list_table->display(); ?>
 		</form>
 		<?php
 	}
@@ -167,12 +170,11 @@ class PageController {
 	/**
 	 * Render the single file view.
 	 *
-	 * @param array $params Args for rendering the view.
-	 *
 	 * @return void
 	 */
-	private function render_single_file_page( array $params ): void {
-		$file = $this->file_controller->get_file_by_id( $params['file_id'] );
+	private function render_single_file_view(): void {
+		$params = $this->get_query_params( array( 'file_id', 'view' ) );
+		$file   = $this->file_controller->get_file_by_id( $params['file_id'] );
 
 		if ( is_wp_error( $file ) ) {
 			?>
@@ -279,6 +281,26 @@ class PageController {
 		<?php
 	}
 
+	/**
+	 * Render the search results view.
+	 *
+	 * @return void
+	 */
+	private function render_search_results_view(): void {
+		$params     = $this->get_query_params( array( 'order', 'orderby', 'search', 'source', 'view' ) );
+		$list_table = $this->get_list_table( $params['view'] );
+
+		$list_table->prepare_items();
+
+		?>
+		<header id="logs-header" class="wc-logs-header">
+			<h2><?php esc_html_e( 'Search results', 'woocommerce' ); ?></h2>
+			<?php $this->render_search_field(); ?>
+		</header>
+		<?php $list_table->display(); ?>
+		<?php
+	}
+
 	/**
 	 * Get the default values for URL query params for FileV2 views.
 	 *
@@ -289,6 +311,7 @@ class PageController {
 			'file_id' => '',
 			'order'   => $this->file_controller::DEFAULTS_GET_FILES['order'],
 			'orderby' => $this->file_controller::DEFAULTS_GET_FILES['orderby'],
+			'search'  => '',
 			'source'  => $this->file_controller::DEFAULTS_GET_FILES['source'],
 			'view'    => 'list_files',
 		);
@@ -297,9 +320,11 @@ class PageController {
 	/**
 	 * Get and validate URL query params for FileV2 views.
 	 *
+	 * @param array $param_keys Optional. The names of the params you want to get.
+	 *
 	 * @return array
 	 */
-	public function get_query_params(): array {
+	public function get_query_params( array $param_keys = array() ): array {
 		$defaults = $this->get_query_param_defaults();
 		$params   = filter_input_array(
 			INPUT_GET,
@@ -307,7 +332,7 @@ class PageController {
 				'file_id' => array(
 					'filter'  => FILTER_CALLBACK,
 					'options' => function( $file_id ) {
-						return sanitize_file_name( $file_id );
+						return sanitize_file_name( wp_unslash( $file_id ) );
 					},
 				),
 				'order'   => array(
@@ -324,6 +349,12 @@ class PageController {
 						'default' => $defaults['orderby'],
 					),
 				),
+				'search'  => array(
+					'filter'  => FILTER_CALLBACK,
+					'options' => function( $search ) {
+						return esc_html( wp_unslash( $search ) );
+					},
+				),
 				'source'  => array(
 					'filter'  => FILTER_CALLBACK,
 					'options' => function( $source ) {
@@ -333,7 +364,7 @@ class PageController {
 				'view'    => array(
 					'filter'  => FILTER_VALIDATE_REGEXP,
 					'options' => array(
-						'regexp'  => '/^(list_files|single_file)$/',
+						'regexp'  => '/^(list_files|single_file|search_results)$/',
 						'default' => $defaults['view'],
 					),
 				),
@@ -342,20 +373,33 @@ class PageController {
 		);
 		$params   = wp_parse_args( $params, $defaults );
 
+		if ( count( $param_keys ) > 0 ) {
+			$params = array_intersect_key( $params, array_flip( $param_keys ) );
+		}
+
 		return $params;
 	}
 
 	/**
 	 * Get and cache an instance of the list table.
 	 *
-	 * @return ListTable
+	 * @param string $view The current view, which determines which list table class to get.
+	 *
+	 * @return FileListTable|SearchListTable
 	 */
-	private function get_list_table(): ListTable {
-		if ( $this->list_table instanceof ListTable ) {
+	private function get_list_table( string $view ) {
+		if ( $this->list_table instanceof WP_List_Table ) {
 			return $this->list_table;
 		}
 
-		$this->list_table = new ListTable( $this->file_controller, $this );
+		switch ( $view ) {
+			case 'list_files':
+				$this->list_table = new FileListTable( $this->file_controller, $this );
+				break;
+			case 'search_results':
+				$this->list_table = new SearchListTable( $this->file_controller, $this );
+				break;
+		}
 
 		return $this->list_table;
 	}
@@ -366,17 +410,19 @@ class PageController {
 	 * @return void
 	 */
 	private function setup_screen_options(): void {
-		$params = $this->get_query_params();
+		$params = $this->get_query_params( array( 'view' ) );
 
-		if ( 'list_files' === $params['view'] ) {
-			// Ensure list table columns are initialized early enough to enable column hiding.
-			$this->get_list_table()->prepare_column_headers();
+		if ( in_array( $params['view'], array( 'list_files', 'search_results' ), true ) ) {
+			$list_table = $this->get_list_table( $params['view'] );
+
+			// Ensure list table columns are initialized early enough to enable column hiding, if available.
+			$list_table->prepare_column_headers();
 
 			add_screen_option(
 				'per_page',
 				array(
-					'default' => 20,
-					'option'  => ListTable::PER_PAGE_USER_OPTION_KEY,
+					'default' => $list_table->get_per_page_default(),
+					'option'  => $list_table::PER_PAGE_USER_OPTION_KEY,
 				)
 			);
 		}
@@ -388,13 +434,14 @@ class PageController {
 	 * @return void
 	 */
 	private function handle_list_table_bulk_actions(): void {
+		$params = $this->get_query_params( array( 'file_id', 'view' ) );
+
 		// Bail if this is not the list table view.
-		$params = $this->get_query_params();
 		if ( 'list_files' !== $params['view'] ) {
 			return;
 		}
 
-		$action = $this->get_list_table()->current_action();
+		$action = $this->get_list_table( $params['view'] )->current_action();
 
 		// phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized
 		$request_uri = isset( $_SERVER['REQUEST_URI'] ) ? wp_unslash( $_SERVER['REQUEST_URI'] ) : $this->get_logs_tab_url();
@@ -409,16 +456,7 @@ class PageController {
 			$sendback = remove_query_arg( array( 'deleted' ), wp_get_referer() );
 
 			// Multiple file_id[] params will be filtered separately, but assigned to $files as an array.
-			$file_ids = filter_input(
-				INPUT_GET,
-				'file_id',
-				FILTER_CALLBACK,
-				array(
-					'options' => function( $file ) {
-						return sanitize_file_name( wp_unslash( $file ) );
-					},
-				)
-			);
+			$file_ids = $params['file_id'];
 
 			if ( ! is_array( $file_ids ) || count( $file_ids ) < 1 ) {
 				wp_safe_redirect( $sendback );
@@ -475,21 +513,21 @@ class PageController {
 	/**
 	 * Format a log file line.
 	 *
-	 * @param string $text        The unformatted log file line.
+	 * @param string $line        The unformatted log file line.
 	 * @param int    $line_number The line number.
 	 *
 	 * @return string
 	 */
-	private function format_line( string $text, int $line_number ): string {
+	private function format_line( string $line, int $line_number ): string {
 		$severity_levels = WC_Log_Levels::get_all_severity_levels();
 		$classes         = array( 'line' );
 
-		$text = esc_html( trim( $text ) );
-		if ( empty( $text ) ) {
-			$text = '&nbsp;';
+		$line = esc_html( trim( $line ) );
+		if ( empty( $line ) ) {
+			$line = '&nbsp;';
 		}
 
-		$segments = explode( ' ', $text, 3 );
+		$segments = explode( ' ', $line, 3 );
 
 		if ( isset( $segments[0] ) && false !== strtotime( $segments[0] ) ) {
 			$classes[]   = 'log-entry';
@@ -508,7 +546,7 @@ class PageController {
 		}
 
 		if ( count( $segments ) > 1 ) {
-			$text = implode( ' ', $segments );
+			$line = implode( ' ', $segments );
 		}
 
 		$classes = implode( ' ', $classes );
@@ -523,8 +561,65 @@ class PageController {
 			),
 			sprintf(
 				'<span class="line-content">%s</span>',
-				wp_kses_post( $text )
+				wp_kses_post( $line )
 			)
 		);
 	}
+
+	/**
+	 * Render a form for searching within log files.
+	 *
+	 * @return void
+	 */
+	private function render_search_field(): void {
+		$params     = $this->get_query_params( array( 'search', 'source' ) );
+		$defaults   = $this->get_query_param_defaults();
+		$file_count = $this->file_controller->get_files( $params, true );
+
+		if ( $file_count > 0 ) {
+			?>
+			<form id="logs-search" class="wc-logs-search" method="get">
+				<fieldset class="wc-logs-search-fieldset">
+					<input type="hidden" name="page" value="wc-status" />
+					<input type="hidden" name="tab" value="logs" />
+					<input type="hidden" name="view" value="search_results" />
+					<?php foreach ( $params as $key => $value ) : ?>
+						<?php if ( $value !== $defaults[ $key ] ) : ?>
+							<input
+								type="hidden"
+								name="<?php echo esc_attr( $key ); ?>"
+								value="<?php echo esc_attr( $value ); ?>"
+							/>
+						<?php endif; ?>
+					<?php endforeach; ?>
+					<label for="logs-search-field">
+						<?php esc_html_e( 'Search within these files', 'woocommerce' ); ?>
+						<input
+							id="logs-search-field"
+							class="wc-logs-search-field"
+							type="text"
+							name="search"
+							value="<?php echo esc_attr( $params['search'] ); ?>"
+						/>
+					</label>
+					<?php submit_button( __( 'Search', 'woocommerce' ), 'secondary', null, false ); ?>
+				</fieldset>
+				<?php if ( $file_count >= $this->file_controller::SEARCH_MAX_FILES ) : ?>
+					<div class="wc-logs-search-notice">
+						<?php
+						printf(
+							// translators: %s is a number.
+							esc_html__(
+								'⚠️ Only %s files can be searched at one time. Try filtering the file list before searching.',
+								'woocommerce'
+							),
+							esc_html( number_format_i18n( $this->file_controller::SEARCH_MAX_FILES ) )
+						);
+						?>
+					</div>
+				<?php endif; ?>
+			</form>
+			<?php
+		}
+	}
 }

plugins/woocommerce/tests/php/src/Internal/Admin/Logging/FileV2/FileControllerTest.php

@@ -233,4 +233,43 @@ class FileControllerTest extends WC_Unit_Test_Case {
 		$this->assertEquals( 2, $deleted );
 		$this->assertEquals( 0, $this->sut->get_files( array(), true ) );
 	}
+
+	/**
+	 * @testdox The search_within_files method should return an associative array of case-insensitive search results.
+	 */
+	public function test_search_within_files(): void {
+		$log_time = time();
+
+		$this->handler->handle( $log_time, 'debug', 'Foo', array( 'source' => 'unit-testing1' ) );
+		$this->handler->handle( $log_time, 'debug', 'Bar', array( 'source' => 'unit-testing1' ) );
+		$this->handler->handle( $log_time, 'debug', 'foobar', array( 'source' => 'unit-testing1' ) );
+		$this->handler->handle( $log_time, 'debug', 'A trip to the food bar', array( 'source' => 'unit-testing2' ) );
+		$this->handler->handle( $log_time, 'debug', 'Hello world', array( 'source' => 'unit-testing2' ) );
+
+		$this->assertEquals( 2, $this->sut->get_files( array(), true ) );
+
+		$file_args = array(
+			'order'   => 'asc',
+			'orderby' => 'source',
+		);
+
+		$results = $this->sut->search_within_files( 'foo', array(), $file_args );
+		$this->assertCount( 3, $results );
+
+		$match = array_shift( $results );
+		$this->assertArrayHasKey( 'file_id', $match );
+		$this->assertArrayHasKey( 'line_number', $match );
+		$this->assertArrayHasKey( 'line', $match );
+		$this->assertEquals( 'unit-testing1-' . gmdate( 'Y-m-d', $log_time ), $match['file_id'] );
+		$this->assertEquals( 1, $match['line_number'] );
+		$this->assertStringContainsString( 'Foo', $match['line'] );
+
+		$match = array_shift( $results );
+		$this->assertEquals( 3, $match['line_number'] );
+		$this->assertStringContainsString( 'foobar', $match['line'] );
+
+		$match = array_shift( $results );
+		$this->assertEquals( 1, $match['line_number'] );
+		$this->assertStringContainsString( 'A trip to the food bar', $match['line'] );
+	}
 }

plugins/woocommerce/tests/php/src/Internal/Admin/Logging/FileV2/FileTest.php

@@ -125,7 +125,7 @@ class FileTest extends WC_Unit_Test_Case {
 	/**
 	 * @testdox Check that get_stream returns a PHP resource representation of the file.
 	 */
-	public function test_get_stream() {
+	public function test_get_and_close_stream() {
 		$filename = Constants::get_constant( 'WC_LOG_DIR' ) . 'test-Source_1-1-2023-10-23-' . wp_hash( 'cheddar' ) . '.log';
 		$resource = fopen( $filename, 'a' );
 		fclose( $resource );
@@ -134,6 +134,10 @@ class FileTest extends WC_Unit_Test_Case {
 		$stream = $file->get_stream();
 
 		$this->assertTrue( is_resource( $stream ) );
+
+		$file->close_stream();
+
+		$this->assertFalse( is_resource( $stream ) );
 	}
 
 	/**
@@ -141,7 +145,7 @@ class FileTest extends WC_Unit_Test_Case {
 	 */
 	public function test_delete() {
 		$filename = Constants::get_constant( 'WC_LOG_DIR' ) . 'test-Source_1-1-' . wp_hash( 'cheddar' ) . '.5.log';
-		$resource = fopen( $filename, 'a' ); // phpcs:ignore WordPress.PHP.NoSilencedErrors
+		$resource = fopen( $filename, 'a' );
 		fclose( $resource );
 		$file = new File( $filename );