Bug 1736331 - Add nsILocalFileMac methods for interacting with extended attributes r=nika

This patch adds support for setting, getting, and reading extended filesystem
attributes on macOS.

Differential Revision: https://phabricator.services.mozilla.com/D133836

xpcom/io/nsILocalFileMac.idl

@@ -168,6 +168,39 @@ interface nsILocalFileMac : nsIFile
      * this is the same as lastModifiedTime.
      */
     readonly attribute int64_t bundleContentsLastModifiedTime;
+
+    /**
+     * Return whether or not the file has an extended attribute.
+     *
+     * @param aAttrName The attribute name to check for.
+     *
+     * @return Whether or not the extended attribute is present.
+     */
+    bool hasXAttr(in ACString aAttrName);
+
+    /**
+     * Get the value of the extended attribute.
+     *
+     * @param aAttrName The attribute name to read.
+     *
+     * @return The extended attribute value.
+     */
+    Array<uint8_t> getXAttr(in ACString aAttrName);
+
+    /**
+     * Set an extended attribute.
+     *
+     * @param aAttrName The attribute name to set a value for.
+     * @param aAttrValue The value to set for the attribute.
+     */
+    void setXAttr(in ACString aAttrName, in Array<uint8_t> aAttrValue);
+
+    /**
+     * Delete an extended attribute.
+     *
+     * @param aAttrName The extended attribute to delete.
+     */
+    void delXAttr(in ACString aAttrName);
 };
 
 %{C++

xpcom/io/nsLocalFile.h

@@ -109,6 +109,11 @@ inline nsresult nsresultForErrno(int aErr) {
     case EFBIG: /*     File too large. */
       return NS_ERROR_FILE_TOO_BIG;
 
+#ifdef ENOATTR
+    case ENOATTR:
+      return NS_ERROR_NOT_AVAILABLE;
+#endif  // ENOATTR
+
     default:
       return NS_ERROR_FAILURE;
   }

xpcom/io/nsLocalFileUnix.cpp

@@ -917,11 +917,7 @@ nsLocalFile::CopyToNative(nsIFile* aNewParent, const nsACString& aNewName) {
 
 #if defined(XP_MACOSX)
     bool quarantined = true;
-    if (getxattr(mPath.get(), "com.apple.quarantine", nullptr, 0, 0, 0) == -1) {
-      if (errno == ENOATTR) {
-        quarantined = false;
-      }
-    }
+    (void)HasXAttr("com.apple.quarantine"_ns, &quarantined);
 #endif
 
     PRFileDesc* oldFD;
@@ -1007,7 +1003,7 @@ nsLocalFile::CopyToNative(nsIFile* aNewParent, const nsACString& aNewName) {
     else if (!quarantined) {
       // If the original file was not in quarantine, lift the quarantine that
       // file creation added because of LSFileQuarantineEnabled.
-      removexattr(newPathName.get(), "com.apple.quarantine", 0);
+      (void)newFile->DelXAttr("com.apple.quarantine"_ns);
     }
 #endif  // defined(XP_MACOSX)
 
@@ -2281,6 +2277,86 @@ nsresult NS_NewLocalFile(const nsAString& aPath, bool aFollowLinks,
 
 #ifdef MOZ_WIDGET_COCOA
 
+NS_IMETHODIMP
+nsLocalFile::HasXAttr(const nsACString& aAttrName, bool* aHasAttr) {
+  NS_ENSURE_ARG_POINTER(aHasAttr);
+
+  nsAutoCString attrName{aAttrName};
+
+  ssize_t size = getxattr(mPath.get(), attrName.get(), nullptr, 0, 0, 0);
+  if (size == -1) {
+    if (errno == ENOATTR) {
+      *aHasAttr = false;
+    } else {
+      return NSRESULT_FOR_ERRNO();
+    }
+  }
+
+  *aHasAttr = true;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::GetXAttr(const nsACString& aAttrName,
+                      nsTArray<uint8_t>& aAttrValue) {
+  aAttrValue.Clear();
+
+  nsAutoCString attrName{aAttrName};
+
+  ssize_t size = getxattr(mPath.get(), attrName.get(), nullptr, 0, 0, 0);
+
+  if (size == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  for (;;) {
+    aAttrValue.SetCapacity(size);
+
+    // The attribute can change between our first call and this call, so we need
+    // to re-check the size and possibly call with a larger buffer.
+    ssize_t newSize = getxattr(mPath.get(), attrName.get(),
+                               aAttrValue.Elements(), size, 0, 0);
+    if (newSize == -1) {
+      return NSRESULT_FOR_ERRNO();
+    }
+
+    if (newSize <= size) {
+      aAttrValue.SetLength(newSize);
+      break;
+    } else {
+      size = newSize;
+    }
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::SetXAttr(const nsACString& aAttrName,
+                      const nsTArray<uint8_t>& aAttrValue) {
+  nsAutoCString attrName{aAttrName};
+
+  if (setxattr(mPath.get(), attrName.get(), aAttrValue.Elements(),
+               aAttrValue.Length(), 0, 0) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsLocalFile::DelXAttr(const nsACString& aAttrName) {
+  nsAutoCString attrName{aAttrName};
+
+  // Ignore removing an attribute that does not exist.
+  if (removexattr(mPath.get(), attrName.get(), 0) == -1) {
+    return NSRESULT_FOR_ERRNO();
+  }
+
+  return NS_OK;
+}
+
 static nsresult MacErrorMapper(OSErr inErr) {
   nsresult outErr;
 

xpcom/tests/unit/test_mac_xattrs.js

@@ -0,0 +1,77 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et: */
+/* 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/. */
+
+const { Assert } = ChromeUtils.import("resource://testing-common/Assert.jsm");
+const { FileUtils } = ChromeUtils.import(
+  "resource://gre/modules/FileUtils.jsm"
+);
+
+async function run_test() {
+  const path = PathUtils.join(await IOUtils.getTempDir(), "macos-xattrs.tmp.d");
+  await IOUtils.makeDirectory(path);
+
+  try {
+    test_macos_xattr(path);
+  } finally {
+    await IOUtils.remove(path, { recursive: true });
+  }
+}
+
+async function test_macos_xattr(tmpDir) {
+  const encoder = new TextEncoder();
+  const path = PathUtils.join(tmpDir, "file.tmp");
+
+  await IOUtils.writeUTF8(path, "");
+
+  const file = new FileUtils.File(path);
+  file.queryInterface(Cc.nsILocalFileMac);
+
+  info("Testing reading an attribute that does not exist");
+  Assert.ok(
+    !file.hasXAttr("bogus.attr"),
+    "File should not have attribute before being set."
+  );
+  Assert.throws(
+    () => file.getXAttr("bogus.attr"),
+    /NS_ERROR_NOT_AVAILABLE/,
+    "Attempting to get an attribute that does not exist throws"
+  );
+
+  {
+    info("Testing setting and reading an attribute");
+    file.setXAttr("bogus.attr", encoder.encode("bogus"));
+    Assert.ok(
+      file.hasXAttr("bogus.attr"),
+      "File should have attribute after being set"
+    );
+    const result = file.getXAttr("bogus.attr");
+
+    Assert.equal(
+      result,
+      encoder.encode("bogus"),
+      "File should have attribute value matching what was set"
+    );
+  }
+
+  info("Testing removing an attribute");
+  file.delXAttr("bogus.attr");
+  Assert.ok(
+    !file.hasXAttr("bogus.attr"),
+    "File should no longer have the attribute after removal"
+  );
+  Assert.throws(
+    () => file.getXAttr("bogus.attr"),
+    /NS_ERROR_NOT_AVAILABLE/,
+    "Attempting to get an attribute after removal results in an error"
+  );
+
+  info("Testing removing an attribute that does not exist");
+  Assert.throws(
+    () => file.delXAttr("bogus.attr"),
+    /NS_ERROR_NOT_AVAILABLE/,
+    "Attempting to remove an attribute that does not exist throws"
+  );
+}

xpcom/tests/unit/xpcshell.ini

@@ -31,6 +31,8 @@ fail-if = os == "android"
 [test_ioutil.js]
 [test_localfile.js]
 [test_mac_bundle.js]
+[test_mac_xattrs.js]
+skip-if = os != "mac"
 [test_nsIMutableArray.js]
 [test_nsIProcess.js]
 skip-if = os == "win" || os == "linux" || os == "android" # bug 582821, bug 1325609, Bug 676998, Bug 1631671