agl@chromium.org
8639940e48
http://code.google.com/p/chromium/wiki/LinuxZygote * Move Chrome specific bits out of base * Move away from the idea of reserved file descriptors (which don't really work with zygotes) * Load resources before forking renderers (means that we don't need communication between the zygote process and the renderers) * Make sure that gdb works against the browser again * Make sure that we have different ASLR between the renderers and the browser. http://codereview.chromium.org/119335 (This is a reland. First landed in r18109, reverted in r18112.) git-svn-id: svn://svn.chromium.org/chrome/trunk/src@18291 0039d316-1c4b-4281-b951-d872f2087c98
67 linhas
2.1 KiB
C++
67 linhas
2.1 KiB
C++
// Copyright (c) 2009 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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#ifndef BASE_GLOBAL_DESCRIPTORS_POSIX_H_
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#define BASE_GLOBAL_DESCRIPTORS_POSIX_H_
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#include "build/build_config.h"
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#include <vector>
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#include <utility>
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#include <stdint.h>
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#include "base/singleton.h"
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namespace base {
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// It's common practice to install file descriptors into well known slot
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// numbers before execing a child; stdin, stdout and stderr are ubiqutous
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// examples.
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//
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// However, when using a zygote model, this becomes troublesome. Since the
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// descriptors which need to be in these slots generally aren't known, any code
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// could open a resource and take one of the reserved descriptors. Simply
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// overwriting the slot isn't a viable solution.
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//
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// We could try to fill the reserved slots as soon as possible, but this is a
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// fragile solution since global constructors etc are able to open files.
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//
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// Instead, we retreat from the idea of installing descriptors in specific
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// slots and add a layer of indirection in the form of this singleton object.
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// It maps from an abstract key to a descriptor. If independent modules each
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// need to define keys, then values should be chosen randomly so as not to
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// collide.
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class GlobalDescriptors {
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public:
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typedef uint32_t Key;
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// Often we want a canonical descriptor for a given Key. In this case, we add
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// the following constant to the key value:
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static const int kBaseDescriptor = 3; // 0, 1, 2 are already taken.
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// Get a descriptor given a key. It is a fatal error if the key is not known.
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int Get(Key key) const;
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// Get a descriptor give a key. Returns -1 on error.
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int MaybeGet(Key key) const;
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typedef std::vector<std::pair<Key, int> > Mapping;
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// Set the descriptor for the given key.
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void Set(Key key, int fd);
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void Reset(const Mapping& mapping) {
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descriptors_ = mapping;
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}
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private:
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GlobalDescriptors() { }
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friend struct DefaultSingletonTraits<GlobalDescriptors>;
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Mapping descriptors_;
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};
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} // namespace base
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#endif // BASE_GLOBAL_DESCRIPTORS_POSIX_H_
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