diff options
Diffstat (limited to 'ipc/chromium/src/base/file_descriptor_shuffle.cc')
-rw-r--r-- | ipc/chromium/src/base/file_descriptor_shuffle.cc | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/ipc/chromium/src/base/file_descriptor_shuffle.cc b/ipc/chromium/src/base/file_descriptor_shuffle.cc new file mode 100644 index 000000000..13f0c1e70 --- /dev/null +++ b/ipc/chromium/src/base/file_descriptor_shuffle.cc @@ -0,0 +1,96 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +// Copyright (c) 2009 The Chromium Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#include "base/file_descriptor_shuffle.h" + +#include <errno.h> +#include <unistd.h> + +#include "base/eintr_wrapper.h" +#include "base/logging.h" + +namespace base { + +bool PerformInjectiveMultimapDestructive( + InjectiveMultimap* m, InjectionDelegate* delegate) { + static const size_t kMaxExtraFDs = 16; + int extra_fds[kMaxExtraFDs]; + unsigned next_extra_fd = 0; + + // DANGER: this function may not allocate. + + for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) { + int temp_fd = -1; + + // We DCHECK the injectiveness of the mapping. + for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) { + DCHECK(i->dest != j->dest) << "Both fd " << i->source + << " and " << j->source << " map to " << i->dest; + } + + const bool is_identity = i->source == i->dest; + + for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) { + if (!is_identity && i->dest == j->source) { + if (temp_fd == -1) { + if (!delegate->Duplicate(&temp_fd, i->dest)) + return false; + if (next_extra_fd < kMaxExtraFDs) { + extra_fds[next_extra_fd++] = temp_fd; + } else { + DLOG(ERROR) << "PerformInjectiveMultimapDestructive overflowed " + << "extra_fds. Leaking file descriptors!"; + } + } + + j->source = temp_fd; + j->close = false; + } + + if (i->close && i->source == j->dest) + i->close = false; + + if (i->close && i->source == j->source) { + i->close = false; + j->close = true; + } + } + + if (!is_identity) { + if (!delegate->Move(i->source, i->dest)) + return false; + } + + if (!is_identity && i->close) + delegate->Close(i->source); + } + + for (unsigned i = 0; i < next_extra_fd; i++) + delegate->Close(extra_fds[i]); + + return true; +} + +bool PerformInjectiveMultimap(const InjectiveMultimap& m_in, + InjectionDelegate* delegate) { + InjectiveMultimap m(m_in); + return PerformInjectiveMultimapDestructive(&m, delegate); +} + +bool FileDescriptorTableInjection::Duplicate(int* result, int fd) { + *result = HANDLE_EINTR(dup(fd)); + return *result >= 0; +} + +bool FileDescriptorTableInjection::Move(int src, int dest) { + return HANDLE_EINTR(dup2(src, dest)) != -1; +} + +void FileDescriptorTableInjection::Close(int fd) { + HANDLE_EINTR(close(fd)); +} + +} // namespace base |