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// Copyright (c) 2011 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/posix/file_descriptor_shuffle.h"
#include <unistd.h>
#include <stddef.h>
#include <ostream>
#include "base/posix/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 must not allocate or lock.
// Cannot use STL iterators here, since debug iterators use locks.
for (size_t i_index = 0; i_index < m->size(); ++i_index) {
InjectiveMultimap::value_type* i = &(*m)[i_index];
int temp_fd = -1;
// We DCHECK the injectiveness of the mapping.
for (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
InjectiveMultimap::value_type* j = &(*m)[j_index];
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 (size_t j_index = i_index + 1; j_index < m->size(); ++j_index) {
InjectiveMultimap::value_type* j = &(*m)[j_index];
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 {
RAW_LOG(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) {
int ret = IGNORE_EINTR(close(fd));
DPCHECK(ret == 0);
}
} // namespace base
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