PyFCGI/include/pyworker.h

/*
 * Copyright (C) 2019 Weber Yann
 * 
 * This file is part of PyFCGI.
 * 
 * PyFCGI is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * any later version.
 * 
 * PyFCGI is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 * 
 * You should have received a copy of the GNU Affero General Public License
 * along with PyFCGI.  If not, see <http://www.gnu.org/licenses/>.
 */
/**@defgroup worker_process Worker processes
 * @brief Processus handling python execution with @ref work() function
 *
 * This kind of process are @ref spawn() by a @ref work_master_proc
 * @section Running Python
 * Running embed python in FCGI mean serving multiple requests with a single
 * python process, meaning :
 * - environnement variable of the living Python process need to be updated
 * - we need a way to communicate with python code
 *
 * @subsection worker_proc_ipc Communicating with python
 * sys.stdout & sys.stderr will be used to communicate in python. Shortly 
 * after python initialize @ref update_python_fd() update these two file
 * objects with freshly created pipes.
 *
 * @subsubsection worker_proc_ipc_piper The piper process
 *
 * When a request arrive, the worker process fork again in a @ref worker_piper() child
 * process that will read the two pipes. Sending stdout to FCGI using printf
 * and stderr to syslog.
 *
 * @subsection worker_proc_environ Updating os.environ
 * os.environ is a special kind of dictionnary, automatically calling 
 * os.putenv() function. This function will attempt (and succeed) to update
 * the real process environnement, making a nasty conflict with libfcgi (trying
 * to free an environnement it did not create anymore...).
 *
 * The os.environ is replaced by a simple python dict by @ref update_pyenv()
 * once a request.
 *
 * @see update_python_path()
 *
 * @ingroup processes
 * @ingroup work_master_proc
 */
/**@file pyworker.h
 * @ingroup worker_process
 */
#ifndef _PYWORKER__H___
#define _PYWORKER__H___

#include "config.h"

#include <fcgiapp.h>
#include <fcgi_stdio.h> /* fcgi library; put it first*/

#define PY_SSIZE_T_CLEAN
#include <Python.h>


#include <unistd.h>
#include <fcntl.h>
#include <syslog.h>
#include <signal.h>
#include <limits.h>
#include <poll.h>
#include <sched.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/wait.h>

#define EXIT_PYERR 42
#define WPIPER_SIG 30
#define PYENTRY_FUNNAME "entrypoint"
#define PIPER_STACK_SZ (1024 * 1024 * 4)

//extern char **environ;

typedef unsigned long int pywrkid_t;
typedef struct piper_args_s piper_args_t;

struct piper_args_s
{
	int wrk_id, pystdout, pystderr, ctl_pipe;
	//int req_id;
	FCGX_Stream *out;
	struct sigaction *act;
};

/**@todo TODO on all request (when updating env ?) update stdin so
 * python will be able to read the request content */

/**@brief the function that initialize the python worker
 * @ingroup worker_process
 * @param char* python_entrypoint a path to a python entrypoint
 * @param int worker uid
 * @param int semid for FCGI access
 * @param int max request before worker restart
 * @return 0 if exit avec max requests
 */
int work(char*, int, int, int);

/**@brief function for a subprocess designed to read stdin & stdout from
 * python & forward them to syslog or FCGI
 * @ingroup worker_process
 * @param int worker id
 * @param int request id
 * @param int pystdout
 * @param int pystderr
 * @param int ctlpipe a pipe closed when the process is ready
 * @note Exit after signal sent by parent & when poll indicate the pipes are
 * empty
 */
/*
void worker_piper(int, int, int, int, int, FCGX_Stream*);
*/
int worker_piper(void*);

/**@brief worker piper sigaction handler
 */
void worker_piper_sighandler(int);

/**@brief Attempt to read the request size from ctl pipe
 * @param int ctl pipe read fd
 * @param size_t* rep_sz
 * @return 0 if no error
 */
int ctl_get_rep_sz(int, size_t*);

/**@brief Import & return the python entrypoint callable
 */
PyObject* import_entrypoint(char* py_entrypoint);

/**@brief Fetch stdout & stderr python flush() function
 * @param PyObject* pystdout_flush
 * @param PyObject* pystderr_flush
 */
void fetch_pyflush(PyObject**, PyObject**);

/**@brief Add . to the embed pythonpath
 */
void update_python_path();

/**@brief Create two pipes for stdout & stderr
 * @ingroup worker_process
 * @params int[2] pystdout
 * @params int[2] pystderr
 */
void update_python_fd(int[2], int[2]);

/**@brief Clear then update python sys.environ using current FCI environ
 * @ingroup worker_process
 * @note The environ has to be set without a call to os.putenv, the problem
 * is that the os.environ is a special mapping calling putenv on setitem...
 * For these reason the os.environ will be replaced by a new dict instance for
 * each request...
 * @param PyObject* os module
 */
void update_pyenv(PyObject*, char**);


void log_expt(int priority);

#endif