Rename server->core (#638)

packages/core/src/tools/read-file.ts

@@ -0,0 +1,131 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import path from 'path';
+import { SchemaValidator } from '../utils/schemaValidator.js';
+import { makeRelative, shortenPath } from '../utils/paths.js';
+import { BaseTool, ToolResult } from './tools.js';
+import { isWithinRoot, processSingleFileContent } from '../utils/fileUtils.js';
+
+/**
+ * Parameters for the ReadFile tool
+ */
+export interface ReadFileToolParams {
+  /**
+   * The absolute path to the file to read
+   */
+  path: string;
+
+  /**
+   * The line number to start reading from (optional)
+   */
+  offset?: number;
+
+  /**
+   * The number of lines to read (optional)
+   */
+  limit?: number;
+}
+
+/**
+ * Implementation of the ReadFile tool logic
+ */
+export class ReadFileTool extends BaseTool<ReadFileToolParams, ToolResult> {
+  static readonly Name: string = 'read_file';
+
+  constructor(private rootDirectory: string) {
+    super(
+      ReadFileTool.Name,
+      'ReadFile',
+      'Reads and returns the content of a specified file from the local filesystem. Handles text, images (PNG, JPG, GIF, WEBP, SVG, BMP), and PDF files. For text files, it can read specific line ranges.',
+      {
+        properties: {
+          path: {
+            description:
+              "The absolute path to the file to read (e.g., '/home/user/project/file.txt'). Relative paths are not supported.",
+            type: 'string',
+          },
+          offset: {
+            description:
+              "Optional: For text files, the 0-based line number to start reading from. Requires 'limit' to be set. Use for paginating through large files.",
+            type: 'number',
+          },
+          limit: {
+            description:
+              "Optional: For text files, maximum number of lines to read. Use with 'offset' to paginate through large files. If omitted, reads the entire file (if feasible, up to a default limit).",
+            type: 'number',
+          },
+        },
+        required: ['path'],
+        type: 'object',
+      },
+    );
+    this.rootDirectory = path.resolve(rootDirectory);
+  }
+
+  validateToolParams(params: ReadFileToolParams): string | null {
+    if (
+      this.schema.parameters &&
+      !SchemaValidator.validate(
+        this.schema.parameters as Record<string, unknown>,
+        params,
+      )
+    ) {
+      return 'Parameters failed schema validation.';
+    }
+    const filePath = params.path;
+    if (!path.isAbsolute(filePath)) {
+      return `File path must be absolute: ${filePath}`;
+    }
+    if (!isWithinRoot(filePath, this.rootDirectory)) {
+      return `File path must be within the root directory (${this.rootDirectory}): ${filePath}`;
+    }
+    if (params.offset !== undefined && params.offset < 0) {
+      return 'Offset must be a non-negative number';
+    }
+    if (params.limit !== undefined && params.limit <= 0) {
+      return 'Limit must be a positive number';
+    }
+    return null;
+  }
+
+  getDescription(params: ReadFileToolParams): string {
+    const relativePath = makeRelative(params.path, this.rootDirectory);
+    return shortenPath(relativePath);
+  }
+
+  async execute(
+    params: ReadFileToolParams,
+    _signal: AbortSignal,
+  ): Promise<ToolResult> {
+    const validationError = this.validateToolParams(params);
+    if (validationError) {
+      return {
+        llmContent: `Error: Invalid parameters provided. Reason: ${validationError}`,
+        returnDisplay: validationError,
+      };
+    }
+
+    const result = await processSingleFileContent(
+      params.path,
+      this.rootDirectory,
+      params.offset,
+      params.limit,
+    );
+
+    if (result.error) {
+      return {
+        llmContent: result.error, // The detailed error for LLM
+        returnDisplay: result.returnDisplay, // User-friendly error
+      };
+    }
+
+    return {
+      llmContent: result.llmContent,
+      returnDisplay: result.returnDisplay,
+    };
+  }
+}