Bug 769312 - Unix errors. r=taras

toolkit/components/osfile/osfile_unix_allthreads.jsm

@@ -0,0 +1,126 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This module defines the thread-agnostic components of the Unix version
+ * of OS.File. It depends on the thread-agnostic cross-platform components
+ * of OS.File.
+ *
+ * It serves the following purposes:
+ * - open libc;
+ * - define OS.Unix.Error;
+ * - define a few constants and types that need to be defined on all platforms.
+ *
+ * This module can be:
+ * - opened from the main thread as a jsm module;
+ * - opened from a chrome worker through importScripts.
+ */
+
+if (typeof Components != "undefined") {
+  // Module is opened as a jsm module
+  var EXPORTED_SYMBOLS = ["OS"];
+  Components.utils.import("resource://gre/modules/ctypes.jsm");
+  Components.utils.import("resource://gre/modules/osfile/osfile_shared_allthreads.jsm");
+} else {
+  // File is included from a chrome worker
+  importScripts("resource://gre/modules/osfile/osfile_shared_allthreads.jsm");
+}
+
+(function(exports) {
+  "use strict";
+  if (!exports.OS || !exports.OS.Shared) {
+    throw new Error("osfile_unix_allthreads.jsm must be loaded after osfile_shared_allthreads.jsm");
+  }
+  if (exports.OS.Shared.Unix) {
+    // Avoid double inclusion
+    return;
+  }
+  exports.OS.Shared.Unix = {};
+
+  let LOG = OS.Shared.LOG.bind(OS.Shared, "Unix", "allthreads");
+
+  // Open libc
+  let libc;
+  let libc_candidates =  [ "libsystem.B.dylib",
+                           "libc.so.6",
+                           "libc.so" ];
+  for (let i = 0; i < libc_candidates.length; ++i) {
+    try {
+      libc = ctypes.open(libc_candidates[i]);
+      break;
+    } catch (x) {
+      LOG("Could not open libc "+libc_candidates[i]);
+    }
+  }
+  if (!libc) {
+    throw new Error("Could not open any libc.");
+  }
+  exports.OS.Shared.Unix.libc = libc;
+
+  // Define declareFFI
+  let declareFFI = OS.Shared.declareFFI.bind(null, libc);
+  exports.OS.Shared.Unix.declareFFI = declareFFI;
+
+  // Define Error
+  let strerror = libc.declare("strerror",
+    ctypes.default_abi,
+    /*return*/ ctypes.char.ptr,
+    /*errnum*/ ctypes.int);
+
+  /**
+   * A File-related error.
+   *
+   * To obtain a human-readable error message, use method |toString|.
+   * To determine the cause of the error, use the various |becauseX|
+   * getters. To determine the operation that failed, use field
+   * |operation|.
+   *
+   * Additionally, this implementation offers a field
+   * |unixErrno|, which holds the OS-specific error
+   * constant. If you need this level of detail, you may match the value
+   * of this field against the error constants of |OS.Constants.libc|.
+   *
+   * @param {string=} operation The operation that failed. If unspecified,
+   * the name of the calling function is taken to be the operation that
+   * failed.
+   * @param {number=} lastError The OS-specific constant detailing the
+   * reason of the error. If unspecified, this is fetched from the system
+   * status.
+   *
+   * @constructor
+   * @extends {OS.Shared.Error}
+   */
+  let OSError = function OSError(operation, errno) {
+    operation = operation || "unknown operation";
+    exports.OS.Shared.Error.call(this, operation);
+    this.unixErrno = errno || ctypes.errno;
+  };
+  OSError.prototype = new exports.OS.Shared.Error();
+  OSError.prototype.toString = function toString() {
+    return "Unix error " + this.unixErrno +
+      " during operation " + this.operation +
+      " (" + strerror(this.unixErrno).readString() + ")";
+  };
+
+  /**
+   * |true| if the error was raised because a file or directory
+   * already exists, |false| otherwise.
+   */
+  Object.defineProperty(OSError.prototype, "becauseExists", {
+    get: function becauseExists() {
+      return this.unixErrno == OS.Constants.libc.EEXISTS;
+    }
+  });
+  /**
+   * |true| if the error was raised because a file or directory
+   * does not exist, |false| otherwise.
+   */
+  Object.defineProperty(OSError.prototype, "becauseNoSuchFile", {
+    get: function becauseNoSuchFile() {
+      return this.unixErrno == OS.Constants.libc.ENOENT;
+    }
+  });
+
+  exports.OS.Shared.Unix.Error = OSError;
+})(this);