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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* process.cpp - Process object
*/
#include "libcamera/internal/process.h"
#include <algorithm>
#include <dirent.h>
#include <fcntl.h>
#include <iostream>
#include <list>
#include <signal.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <vector>
#include "libcamera/internal/event_notifier.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/utils.h"
/**
* \file process.h
* \brief Process object
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(Process)
/**
* \class ProcessManager
* \brief Manager of processes
*
* The ProcessManager singleton keeps track of all created Process instances,
* and manages the signal handling involved in terminating processes.
*/
namespace {
void sigact(int signal, siginfo_t *info, void *ucontext)
{
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-result"
/*
* We're in a signal handler so we can't log any message, and we need
* to continue anyway.
*/
char data = 0;
write(ProcessManager::instance()->writePipe(), &data, sizeof(data));
#pragma GCC diagnostic pop
const struct sigaction &oldsa = ProcessManager::instance()->oldsa();
if (oldsa.sa_flags & SA_SIGINFO) {
oldsa.sa_sigaction(signal, info, ucontext);
} else {
if (oldsa.sa_handler != SIG_IGN && oldsa.sa_handler != SIG_DFL)
oldsa.sa_handler(signal);
}
}
} /* namespace */
void ProcessManager::sighandler([[maybe_unused]] EventNotifier *notifier)
{
char data;
ssize_t ret = read(pipe_[0], &data, sizeof(data));
if (ret < 0) {
LOG(Process, Error)
<< "Failed to read byte from signal handler pipe";
return;
}
for (auto it = processes_.begin(); it != processes_.end(); ) {
Process *process = *it;
int wstatus;
pid_t pid = waitpid(process->pid_, &wstatus, WNOHANG);
if (process->pid_ != pid) {
++it;
continue;
}
it = processes_.erase(it);
process->died(wstatus);
}
}
/**
* \brief Register process with process manager
* \param[in] proc Process to register
*
* This method registers the \a proc with the process manager. It
* shall be called by the parent process after successfully forking, in
* order to let the parent signal process termination.
*/
void ProcessManager::registerProcess(Process *proc)
{
processes_.push_back(proc);
}
ProcessManager *ProcessManager::self_ = nullptr;
/**
* \brief Construct a ProcessManager instance
*
* The ProcessManager class is meant to only be instantiated once, by the
* CameraManager.
*/
ProcessManager::ProcessManager()
{
if (self_)
LOG(Process, Fatal)
<< "Multiple ProcessManager objects are not allowed";
sigaction(SIGCHLD, NULL, &oldsa_);
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = &sigact;
memcpy(&sa.sa_mask, &oldsa_.sa_mask, sizeof(sa.sa_mask));
sigaddset(&sa.sa_mask, SIGCHLD);
sa.sa_flags = oldsa_.sa_flags | SA_SIGINFO;
sigaction(SIGCHLD, &sa, NULL);
if (pipe2(pipe_, O_CLOEXEC | O_DIRECT | O_NONBLOCK))
LOG(Process, Fatal)
<< "Failed to initialize pipe for signal handling";
sigEvent_ = new EventNotifier(pipe_[0], EventNotifier::Read);
sigEvent_->activated.connect(this, &ProcessManager::sighandler);
self_ = this;
}
ProcessManager::~ProcessManager()
{
sigaction(SIGCHLD, &oldsa_, NULL);
delete sigEvent_;
close(pipe_[0]);
close(pipe_[1]);
self_ = nullptr;
}
/**
* \brief Retrieve the Process manager instance
*
* The ProcessManager is constructed by the CameraManager. This function shall
* be used to retrieve the single instance of the manager.
*
* \return The Process manager instance
*/
ProcessManager *ProcessManager::instance()
{
return self_;
}
/**
* \brief Retrieve the Process manager's write pipe
*
* This method is meant only to be used by the static signal handler.
*
* \return Pipe for writing
*/
int ProcessManager::writePipe() const
{
return pipe_[1];
}
/**
* \brief Retrive the old signal action data
*
* This method is meant only to be used by the static signal handler.
*
* \return The old signal action data
*/
const struct sigaction &ProcessManager::oldsa() const
{
return oldsa_;
}
/**
* \class Process
* \brief Process object
*
* The Process class models a process, and simplifies spawning new processes
* and monitoring the exiting of a process.
*/
/**
* \enum Process::ExitStatus
* \brief Exit status of process
* \var Process::NotExited
* The process hasn't exited yet
* \var Process::NormalExit
* The process exited normally, either via exit() or returning from main
* \var Process::SignalExit
* The process was terminated by a signal (this includes crashing)
*/
Process::Process()
: pid_(-1), running_(false), exitStatus_(NotExited), exitCode_(0)
{
}
Process::~Process()
{
kill();
/* \todo wait for child process to exit */
}
/**
* \brief Fork and exec a process, and close fds
* \param[in] path Path to executable
* \param[in] args Arguments to pass to executable (optional)
* \param[in] fds Vector of file descriptors to keep open (optional)
*
* Fork a process, and exec the executable specified by path. Prior to
* exec'ing, but after forking, all file descriptors except for those
* specified in fds will be closed.
*
* All indexes of args will be incremented by 1 before being fed to exec(),
* so args[0] should not need to be equal to path.
*
* \return Zero on successful fork, exec, and closing the file descriptors,
* or a negative error code otherwise
*/
int Process::start(const std::string &path,
const std::vector<std::string> &args,
const std::vector<int> &fds)
{
int ret;
if (running_)
return 0;
int childPid = fork();
if (childPid == -1) {
ret = -errno;
LOG(Process, Error) << "Failed to fork: " << strerror(-ret);
return ret;
} else if (childPid) {
pid_ = childPid;
ProcessManager::instance()->registerProcess(this);
running_ = true;
return 0;
} else {
if (isolate())
_exit(EXIT_FAILURE);
closeAllFdsExcept(fds);
unsetenv("LIBCAMERA_LOG_FILE");
const char **argv = new const char *[args.size() + 2];
unsigned int len = args.size();
argv[0] = path.c_str();
for (unsigned int i = 0; i < len; i++)
argv[i+1] = args[i].c_str();
argv[len+1] = nullptr;
execv(path.c_str(), (char **)argv);
exit(EXIT_FAILURE);
}
}
void Process::closeAllFdsExcept(const std::vector<int> &fds)
{
std::vector<int> v(fds);
sort(v.begin(), v.end());
DIR *dir = opendir("/proc/self/fd");
if (!dir)
return;
int dfd = dirfd(dir);
struct dirent *ent;
while ((ent = readdir(dir)) != nullptr) {
char *endp;
int fd = strtoul(ent->d_name, &endp, 10);
if (*endp)
continue;
if (fd >= 0 && fd != dfd &&
!std::binary_search(v.begin(), v.end(), fd))
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