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// 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.
#ifndef BASE_ZYGOTE_MANAGER_H_
#define BASE_ZYGOTE_MANAGER_H_
#include "build/build_config.h"
#if defined(OS_LINUX)
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <map>
#include <string>
#include <utility>
#include <vector>
#include "base/pickle.h"
#include "base/time.h"
#include "base/process_util.h" // for file_handle_mapping_vector
namespace base {
class ZygoteManager {
public:
// The normal way to get a ZygoteManager is via this singleton factory.
static ZygoteManager* Get();
ZygoteManager() :
server_fd_(-1), client_fd_(-1), canary_fd_(-1), lockfd_(-1) {
}
~ZygoteManager();
// Measure round trip time. Return true on success.
// Only used during testing.
bool Ping(base::TimeDelta* delta);
// Start the zygote manager.
// Called only once, but returns many times.
// Returns once in original process and once in each spawned child.
// In original process, returns NULL.
// In child processes, returns the argv to use for the child.
// In Chromium, called from ChromeMain().
std::vector<std::string>* Start();
// Like longjmp() and base::LaunchApp().
// Ask the fork server to spawn a new process with
// the given commandline and the given file descriptors.
// Returns process id of copy, or -1 on failure.
// In Chromium, called from base::ForkApp(), which is
// called from BrowserRenderProcessHost::Init().
pid_t LongFork(const std::vector<std::string>& argv,
const file_handle_mapping_vector& fds_to_remap);
// Tell ZygoteManager that we expect the given process to
// exit on its own soon. If it doesn't die within a few
// seconds, kill it. Does not block (unless pipe to server full).
// In Chromium, called from ProcessWatcher::EnsureProcessTerminated().
void EnsureProcessTerminated(pid_t childpid);
// Open a file, or retrieve a previously cached file descriptor
// for this file. The files are opened for readonly access.
// Caution: do not seek file descriptors returned
// by this API, as all children share the same file objects, so
// a seek on one is a seek on all.
// Works even if the file is unlinked after the first call
// (e.g. when an app is updated by the linux system autoupdater).
// Returns file descriptor, or -1 for error.
// In Chromium, called from MemoryMappedFile::MapFileToMemory().
// Only allows openeing files named .pak in reasonable looking locations.
int OpenFile(const std::string& filename);
private:
int UnpickleHeader(const Pickle& reply, void** iter);
// Returns false on EOF
// Sets *newargv to a new commandline if the remote side requested a fork.
bool ReadAndHandleMessage(std::vector<std::string>** newargv);
void PingHandler(const Pickle& request, void* iter, Pickle* reply,
std::vector<std::string>** newargv);
bool LongForkHandler(const Pickle& request, void* iter, Pickle* reply,
std::vector<std::string>** newargv,
const int wire_fds[], int num_wire_fds);
void EnsureProcessTerminatedHandler(const Pickle& request, void* iter);
bool OpenFileHandler(const Pickle& request, void* iter, Pickle* reply,
::msghdr* msg);
// The fd used by the server to receive requests
int server_fd_;
// The fd used by the clients to send requests
int client_fd_;
// fd used only to notify server of destruction.
int canary_fd_;
// Temporary file used only for locking.
// Each client must do its own open for locking to work;
// inherited file descriptors can't lock each other out.
// FIXME: locking is lame.
std::string lockfile_;
int lockfd_;
enum message_kind_t { ZMPING, ZMPINGED,
ZMFORK, ZMFORKED,
ZMREAP,
ZMOPEN, ZMOPENED,
ZMBAD };
// See common/reserved_file_descriptors.h for who uses the reserved
// file descriptors. kReservedFds is one plus the highest fd mentioned there.
// TODO(dkegel): move kReservedFds to reserved_file_descriptors.h
static const int kReservedFds = 5;
static const int kMAX_MSG_LEN = 2000;
static const int kMAX_CMSG_LEN = 100;
static const char kZMagic[];
char msg_buf_[kMAX_MSG_LEN];
char cmsg_buf_[kMAX_CMSG_LEN];
// Where we remember file descriptors for already-opened files.
// Both client and server maintain this table.
// Client should check the table before requesting the
// server to open a file, as it might have been already
// opened before this client was forked.
std::map<std::string, int> cached_fds_;
};
} // namespace base
#endif // defined(OS_LINUX)
#endif // BASE_ZYGOTE_MANAGER_H_
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