Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 295 insertions, 0 deletions

diff --git a/toolkit/xre/MultiInstanceLock.cpp b/toolkit/xre/MultiInstanceLock.cpp
new file mode 100644
index 0000000000..230df80a1f
--- /dev/null
+++ b/toolkit/xre/MultiInstanceLock.cpp
@@ -0,0 +1,295 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#include "MultiInstanceLock.h"
+
+#include "commonupdatedir.h"  // for GetInstallHash
+#include "mozilla/UniquePtr.h"
+#include "nsPrintfCString.h"
+#include "nsPromiseFlatString.h"
+#include "updatedefines.h"  // for NS_t* definitions
+
+#ifdef XP_WIN
+#  include <shlwapi.h>
+#else
+#  include <fcntl.h>
+#  include <sys/stat.h>
+#  include <sys/types.h>
+#endif
+
+#ifdef XP_WIN
+#  include "WinUtils.h"
+#endif
+
+#ifdef MOZ_WIDGET_COCOA
+#  include "nsILocalFileMac.h"
+#endif
+
+namespace mozilla {
+
+static bool GetLockFileName(const char* nameToken, const char16_t* installPath,
+                            nsCString& filePath) {
+#ifdef XP_WIN
+  // On Windows, the lock file is placed at the path
+  // [updateDirectory]\[nameToken]-[pathHash], so first we need to get the
+  // update directory path and then append the file name.
+
+  // Note: This will return something like
+  //   C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38\updates\<hash>
+  // But we actually are going to want to return the root update directory,
+  // the grandparent of this directory, which will look something like this:
+  //   C:\ProgramData\Mozilla-1de4eec8-1241-4177-a864-e594e8d1fb38
+  mozilla::UniquePtr<wchar_t[]> updateDir;
+  HRESULT hr = GetCommonUpdateDirectory(
+      reinterpret_cast<const wchar_t*>(installPath), updateDir);
+  if (FAILED(hr)) {
+    return false;
+  }
+
+  // For the path manipulation that we are about to do, it is important that
+  // the update directory have no trailing slash.
+  size_t len = wcslen(updateDir.get());
+  if (len == 0) {
+    return false;
+  }
+  if (updateDir.get()[len - 1] == '/' || updateDir.get()[len - 1] == '\\') {
+    updateDir.get()[len - 1] = '\0';
+  }
+
+  wchar_t* hashPtr = PathFindFileNameW(updateDir.get());
+  // PathFindFileNameW returns a pointer to the beginning of the string on
+  // failure.
+  if (hashPtr == updateDir.get()) {
+    return false;
+  }
+
+  // We need to make a copy of the hash before we modify updateDir to get the
+  // root update dir.
+  size_t hashSize = wcslen(hashPtr) + 1;
+  mozilla::UniquePtr<wchar_t[]> hash = mozilla::MakeUnique<wchar_t[]>(hashSize);
+  errno_t error = wcscpy_s(hash.get(), hashSize, hashPtr);
+  if (error != 0) {
+    return false;
+  }
+
+  // Get the root update dir from the update dir.
+  BOOL success = PathRemoveFileSpecW(updateDir.get());
+  if (!success) {
+    return false;
+  }
+  success = PathRemoveFileSpecW(updateDir.get());
+  if (!success) {
+    return false;
+  }
+
+  filePath =
+      nsPrintfCString("%s\\%s-%s", NS_ConvertUTF16toUTF8(updateDir.get()).get(),
+                      nameToken, NS_ConvertUTF16toUTF8(hash.get()).get());
+
+#else
+  mozilla::UniquePtr<NS_tchar[]> pathHash;
+  if (!GetInstallHash(installPath, pathHash)) {
+    return false;
+  }
+
+  // On POSIX platforms the base path is /tmp/[vendor][nameToken]-[pathHash].
+  filePath = nsPrintfCString("/tmp/%s%s-%s", MOZ_APP_VENDOR, nameToken,
+                             pathHash.get());
+
+#endif
+
+  return true;
+}
+
+MultiInstLockHandle OpenMultiInstanceLock(const char* nameToken,
+                                          const char16_t* installPath) {
+  nsCString filePath;
+  if (!GetLockFileName(nameToken, installPath, filePath)) {
+    return MULTI_INSTANCE_LOCK_HANDLE_ERROR;
+  }
+
+  // Open a file handle with full privileges and sharing, and then attempt to
+  // take a shared (nonexclusive, read-only) lock on it.
+#ifdef XP_WIN
+  HANDLE h =
+      ::CreateFileW(PromiseFlatString(NS_ConvertUTF8toUTF16(filePath)).get(),
+                    GENERIC_READ | GENERIC_WRITE,
+                    FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                    nullptr, OPEN_ALWAYS, 0, nullptr);
+  if (h != INVALID_HANDLE_VALUE) {
+    // The LockFileEx functions always require an OVERLAPPED structure even
+    // though we did not open the lock file for overlapped I/O.
+    OVERLAPPED o = {0};
+    if (!::LockFileEx(h, LOCKFILE_FAIL_IMMEDIATELY, 0, 1, 0, &o)) {
+      CloseHandle(h);
+      h = INVALID_HANDLE_VALUE;
+    }
+  }
+  return h;
+
+#else
+  int fd = ::open(PromiseFlatCString(filePath).get(),
+                  O_CLOEXEC | O_CREAT | O_NOFOLLOW,
+                  S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
+  if (fd != -1) {
+    // We would like to ensure that the lock file is deleted when we are done
+    // with it. The normal way to do that would be to call unlink on it right
+    // now, but that would immediately delete the name from the file system, and
+    // we need other instances to be able to open that name and get the same
+    // inode, so we can't unlink the file before we're done with it. This means
+    // we accept some unreliability in getting the file deleted, but it's a zero
+    // byte file in the tmp directory, so having it stay around isn't the worst.
+    struct flock l = {0};
+    l.l_start = 0;
+    l.l_len = 0;
+    l.l_type = F_RDLCK;
+    if (::fcntl(fd, F_SETLK, &l)) {
+      ::close(fd);
+      fd = -1;
+    }
+  }
+  return fd;
+
+#endif
+}
+
+void ReleaseMultiInstanceLock(MultiInstLockHandle lock) {
+  if (lock != MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+#ifdef XP_WIN
+    OVERLAPPED o = {0};
+    ::UnlockFileEx(lock, 0, 1, 0, &o);
+    ::CloseHandle(lock);
+
+#else
+    // If we're the last instance, then unlink the lock file. There is a race
+    // condition here that may cause an instance to fail to open the same inode
+    // as another even though they use the same path, but there's no reasonable
+    // way to avoid that without skipping deleting the file at all, so we accept
+    // that risk.
+    bool otherInstance = true;
+    if (IsOtherInstanceRunning(lock, &otherInstance) && !otherInstance) {
+      // Recover the file's path so we can unlink it.
+      // There's no error checking in here because we're content to let the file
+      // hang around if any of this fails (which can happen if for example we're
+      // on a system where /proc/self/fd does not exist); this is a zero-byte
+      // file in the tmp directory after all.
+      UniquePtr<NS_tchar[]> linkPath = MakeUnique<NS_tchar[]>(MAXPATHLEN + 1);
+      NS_tsnprintf(linkPath.get(), MAXPATHLEN + 1, "/proc/self/fd/%d", lock);
+      UniquePtr<NS_tchar[]> lockFilePath =
+          MakeUnique<NS_tchar[]>(MAXPATHLEN + 1);
+      if (::readlink(linkPath.get(), lockFilePath.get(), MAXPATHLEN + 1) !=
+          -1) {
+        ::unlink(lockFilePath.get());
+      }
+    }
+    // Now close the lock file, which will release the lock.
+    ::close(lock);
+#endif
+  }
+}
+
+bool IsOtherInstanceRunning(MultiInstLockHandle lock, bool* aResult) {
+  // Every running instance has opened a readonly lock, and read locks prevent
+  // write locks from being opened, so to see if we are the only instance, we
+  // attempt to take a write lock, and if it succeeds then that must mean there
+  // are no other read locks open and therefore no other instances.
+  if (lock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    return false;
+  }
+
+#ifdef XP_WIN
+  // We need to release the lock we're holding before we would be allowed to
+  // take an exclusive lock, and if that succeeds we need to release it too
+  // in order to get our shared lock back. This procedure is not atomic, so we
+  // accept the risk of the scheduler deciding to ruin our day between these
+  // operations; we'd get a false negative in a different instance's check.
+  OVERLAPPED o = {0};
+  // Release our current shared lock.
+  if (!::UnlockFileEx(lock, 0, 1, 0, &o)) {
+    return false;
+  }
+  // Attempt to take an exclusive lock.
+  bool rv = false;
+  if (::LockFileEx(lock, LOCKFILE_EXCLUSIVE_LOCK | LOCKFILE_FAIL_IMMEDIATELY, 0,
+                   1, 0, &o)) {
+    // We got the exclusive lock, so now release it.
+    ::UnlockFileEx(lock, 0, 1, 0, &o);
+    *aResult = false;
+    rv = true;
+  } else if (::GetLastError() == ERROR_LOCK_VIOLATION) {
+    // We didn't get the exclusive lock because of outstanding shared locks.
+    *aResult = true;
+    rv = true;
+  }
+  // Attempt to reclaim the shared lock we released at the beginning.
+  if (!::LockFileEx(lock, LOCKFILE_FAIL_IMMEDIATELY, 0, 1, 0, &o)) {
+    rv = false;
+  }
+  return rv;
+
+#else
+  // See if we would be allowed to set a write lock (no need to actually do so).
+  struct flock l = {0};
+  l.l_start = 0;
+  l.l_len = 0;
+  l.l_type = F_WRLCK;
+  if (::fcntl(lock, F_GETLK, &l)) {
+    return false;
+  }
+  *aResult = l.l_type != F_UNLCK;
+  return true;
+
+#endif
+}
+
+already_AddRefed<nsIFile> GetNormalizedAppFile(nsIFile* aAppFile) {
+  // If we're given an app file, use it; otherwise, get it from the ambient
+  // directory service.
+  nsresult rv;
+  nsCOMPtr<nsIFile> appFile;
+  if (aAppFile) {
+    rv = aAppFile->Clone(getter_AddRefs(appFile));
+    NS_ENSURE_SUCCESS(rv, nullptr);
+  } else {
+    nsCOMPtr<nsIProperties> dirSvc =
+        do_GetService(NS_DIRECTORY_SERVICE_CONTRACTID);
+    NS_ENSURE_TRUE(dirSvc, nullptr);
+
+    rv = dirSvc->Get(XRE_EXECUTABLE_FILE, NS_GET_IID(nsIFile),
+                     getter_AddRefs(appFile));
+    NS_ENSURE_SUCCESS(rv, nullptr);
+  }
+
+  // It is possible that the path we have is on a case insensitive
+  // filesystem in which case the path may vary depending on how the
+  // application is called. We want to normalize the case somehow.
+  // On Linux XRE_EXECUTABLE_FILE already seems to be set to the correct path.
+  //
+  // See similar nsXREDirProvider::GetInstallHash. The main difference here is
+  // to allow lookup to fail on OSX, because some tests use a nonexistent
+  // appFile.
+#ifdef XP_WIN
+  // Windows provides a way to get the correct case.
+  if (!mozilla::widget::WinUtils::ResolveJunctionPointsAndSymLinks(appFile)) {
+    NS_WARNING("Failed to resolve install directory.");
+  }
+#elif defined(MOZ_WIDGET_COCOA)
+  // On OSX roundtripping through an FSRef fixes the case.
+  FSRef ref;
+  nsCOMPtr<nsILocalFileMac> macFile = do_QueryInterface(appFile);
+  if (macFile && NS_SUCCEEDED(macFile->GetFSRef(&ref)) &&
+      NS_SUCCEEDED(
+          NS_NewLocalFileWithFSRef(&ref, true, getter_AddRefs(macFile)))) {
+    appFile = static_cast<nsIFile*>(macFile);
+  } else {
+    NS_WARNING("Failed to resolve install directory.");
+  }
+#endif
+
+  return appFile.forget();
+}
+
+};  // namespace mozilla