97 lines
2.6 KiB
C++
97 lines
2.6 KiB
C++
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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/posix/file_descriptor_shuffle.h"
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#include <unistd.h>
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#include <stddef.h>
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#include <ostream>
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#include "base/posix/eintr_wrapper.h"
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#include "base/logging.h"
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namespace base {
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bool PerformInjectiveMultimapDestructive(
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InjectiveMultimap* m, InjectionDelegate* delegate) {
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static const size_t kMaxExtraFDs = 16;
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int extra_fds[kMaxExtraFDs];
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unsigned next_extra_fd = 0;
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// DANGER: this function may not allocate.
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for (InjectiveMultimap::iterator i = m->begin(); i != m->end(); ++i) {
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int temp_fd = -1;
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// We DCHECK the injectiveness of the mapping.
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for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
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DCHECK(i->dest != j->dest) << "Both fd " << i->source
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<< " and " << j->source << " map to " << i->dest;
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}
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const bool is_identity = i->source == i->dest;
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for (InjectiveMultimap::iterator j = i + 1; j != m->end(); ++j) {
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if (!is_identity && i->dest == j->source) {
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if (temp_fd == -1) {
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if (!delegate->Duplicate(&temp_fd, i->dest))
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return false;
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if (next_extra_fd < kMaxExtraFDs) {
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extra_fds[next_extra_fd++] = temp_fd;
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} else {
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RAW_LOG(ERROR, "PerformInjectiveMultimapDestructive overflowed "
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"extra_fds. Leaking file descriptors!");
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}
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}
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j->source = temp_fd;
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j->close = false;
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}
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if (i->close && i->source == j->dest)
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i->close = false;
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if (i->close && i->source == j->source) {
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i->close = false;
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j->close = true;
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}
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}
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if (!is_identity) {
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if (!delegate->Move(i->source, i->dest))
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return false;
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}
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if (!is_identity && i->close)
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delegate->Close(i->source);
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}
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for (unsigned i = 0; i < next_extra_fd; i++)
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delegate->Close(extra_fds[i]);
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return true;
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}
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bool PerformInjectiveMultimap(const InjectiveMultimap& m_in,
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InjectionDelegate* delegate) {
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InjectiveMultimap m(m_in);
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return PerformInjectiveMultimapDestructive(&m, delegate);
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}
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bool FileDescriptorTableInjection::Duplicate(int* result, int fd) {
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*result = HANDLE_EINTR(dup(fd));
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return *result >= 0;
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}
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bool FileDescriptorTableInjection::Move(int src, int dest) {
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return HANDLE_EINTR(dup2(src, dest)) != -1;
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}
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void FileDescriptorTableInjection::Close(int fd) {
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int ret = HANDLE_EINTR(close(fd));
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DPCHECK(ret == 0);
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}
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} // namespace base
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