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+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* The purpose of this file is to store the code that MOST mpm's will need
+ * this does not mean a function only goes into this file if every MPM needs
+ * it. It means that if a function is needed by more than one MPM, and
+ * future maintenance would be served by making the code common, then the
+ * function belongs here.
+ *
+ * This is going in src/main because it is not platform specific, it is
+ * specific to multi-process servers, but NOT to Unix. Which is why it
+ * does not belong in src/os/unix
+ */
+
+/**
+ * @file mpm_common.h
+ * @brief Multi-Processing Modules functions
+ *
+ * @defgroup APACHE_MPM Multi-Processing Modules
+ * @ingroup APACHE
+ * @{
+ */
+
+#ifndef APACHE_MPM_COMMON_H
+#define APACHE_MPM_COMMON_H
+
+#include "ap_config.h"
+#include "ap_mpm.h"
+#include "scoreboard.h"
+
+#if APR_HAVE_NETINET_TCP_H
+#include <netinet/tcp.h> /* for TCP_NODELAY */
+#endif
+
+#include "apr_proc_mutex.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* The maximum length of the queue of pending connections, as defined
+ * by listen(2). Under some systems, it should be increased if you
+ * are experiencing a heavy TCP SYN flood attack.
+ *
+ * It defaults to 511 instead of 512 because some systems store it
+ * as an 8-bit datatype; 512 truncated to 8-bits is 0, while 511 is
+ * 255 when truncated.
+ */
+#ifndef DEFAULT_LISTENBACKLOG
+#define DEFAULT_LISTENBACKLOG 511
+#endif
+
+/* Signal used to gracefully restart */
+#define AP_SIG_GRACEFUL SIGUSR1
+
+/* Signal used to gracefully restart (without SIG prefix) */
+#define AP_SIG_GRACEFUL_SHORT USR1
+
+/* Signal used to gracefully restart (as a quoted string) */
+#define AP_SIG_GRACEFUL_STRING "SIGUSR1"
+
+/* Signal used to gracefully stop */
+#define AP_SIG_GRACEFUL_STOP SIGWINCH
+
+/* Signal used to gracefully stop (without SIG prefix) */
+#define AP_SIG_GRACEFUL_STOP_SHORT WINCH
+
+/* Signal used to gracefully stop (as a quoted string) */
+#define AP_SIG_GRACEFUL_STOP_STRING "SIGWINCH"
+
+/**
+ * Callback function used for ap_reclaim_child_processes() and
+ * ap_relieve_child_processes(). The callback function will be
+ * called for each terminated child process.
+ */
+typedef void ap_reclaim_callback_fn_t(int childnum, pid_t pid,
+ ap_generation_t gen);
+
+#if (!defined(WIN32) && !defined(NETWARE)) || defined(DOXYGEN)
+/**
+ * Make sure all child processes that have been spawned by the parent process
+ * have died. This includes process registered as "other_children".
+ *
+ * @param terminate Either 1 or 0. If 1, send the child processes SIGTERM
+ * each time through the loop. If 0, give the process time to die
+ * on its own before signalling it.
+ * @param mpm_callback Callback invoked for each dead child process
+ *
+ * @note The MPM child processes which are reclaimed are those listed
+ * in the scoreboard as well as those currently registered via
+ * ap_register_extra_mpm_process().
+ */
+AP_DECLARE(void) ap_reclaim_child_processes(int terminate,
+ ap_reclaim_callback_fn_t *mpm_callback);
+
+/**
+ * Catch any child processes that have been spawned by the parent process
+ * which have exited. This includes processes registered as "other_children".
+ *
+ * @param mpm_callback Callback invoked for each dead child process
+
+ * @note The MPM child processes which are relieved are those listed
+ * in the scoreboard as well as those currently registered via
+ * ap_register_extra_mpm_process().
+ */
+AP_DECLARE(void) ap_relieve_child_processes(ap_reclaim_callback_fn_t *mpm_callback);
+
+/**
+ * Tell ap_reclaim_child_processes() and ap_relieve_child_processes() about
+ * an MPM child process which has no entry in the scoreboard.
+ * @param pid The process id of an MPM child process which should be
+ * reclaimed when ap_reclaim_child_processes() is called.
+ * @param gen The generation of this MPM child process.
+ *
+ * @note If an extra MPM child process terminates prior to calling
+ * ap_reclaim_child_processes(), remove it from the list of such processes
+ * by calling ap_unregister_extra_mpm_process().
+ */
+AP_DECLARE(void) ap_register_extra_mpm_process(pid_t pid, ap_generation_t gen);
+
+/**
+ * Unregister an MPM child process which was previously registered by a
+ * call to ap_register_extra_mpm_process().
+ * @param pid The process id of an MPM child process which no longer needs to
+ * be reclaimed.
+ * @param old_gen Set to the server generation of the process, if found.
+ * @return 1 if the process was found and removed, 0 otherwise
+ */
+AP_DECLARE(int) ap_unregister_extra_mpm_process(pid_t pid, ap_generation_t *old_gen);
+
+/**
+ * Safely signal an MPM child process, if the process is in the
+ * current process group. Otherwise fail.
+ * @param pid the process id of a child process to signal
+ * @param sig the signal number to send
+ * @return APR_SUCCESS if signal is sent, otherwise an error as per kill(3);
+ * APR_EINVAL is returned if passed either an invalid (< 1) pid, or if
+ * the pid is not in the current process group
+ */
+AP_DECLARE(apr_status_t) ap_mpm_safe_kill(pid_t pid, int sig);
+
+/**
+ * Log why a child died to the error log, if the child died without the
+ * parent signalling it.
+ * @param pid The child that has died
+ * @param why The return code of the child process
+ * @param status The status returned from ap_wait_or_timeout
+ * @return 0 on success, APEXIT_CHILDFATAL if MPM should terminate
+ */
+AP_DECLARE(int) ap_process_child_status(apr_proc_t *pid, apr_exit_why_e why, int status);
+
+AP_DECLARE(apr_status_t) ap_fatal_signal_setup(server_rec *s, apr_pool_t *in_pconf);
+AP_DECLARE(apr_status_t) ap_fatal_signal_child_setup(server_rec *s);
+
+#endif /* (!WIN32 && !NETWARE) || DOXYGEN */
+
+/**
+ * Pool cleanup for end-generation hook implementation
+ * (core httpd function)
+ */
+apr_status_t ap_mpm_end_gen_helper(void *unused);
+
+/**
+ * Run the monitor hook (once every ten calls), determine if any child
+ * process has died and, if none died, sleep one second.
+ * @param status The return code if a process has died
+ * @param exitcode The returned exit status of the child, if a child process
+ * dies, or the signal that caused the child to die.
+ * @param ret The process id of the process that died
+ * @param p The pool to allocate out of
+ * @param s The server_rec to pass
+ */
+AP_DECLARE(void) ap_wait_or_timeout(apr_exit_why_e *status, int *exitcode,
+ apr_proc_t *ret, apr_pool_t *p,
+ server_rec *s);
+
+#if defined(TCP_NODELAY)
+/**
+ * Turn off the nagle algorithm for the specified socket. The nagle algorithm
+ * says that we should delay sending partial packets in the hopes of getting
+ * more data. There are bad interactions between persistent connections and
+ * Nagle's algorithm that have severe performance penalties.
+ * @param s The socket to disable nagle for.
+ */
+void ap_sock_disable_nagle(apr_socket_t *s);
+#else
+#define ap_sock_disable_nagle(s) /* NOOP */
+#endif
+
+#ifdef HAVE_GETPWNAM
+/**
+ * Convert a username to a numeric ID
+ * @param name The name to convert
+ * @return The user id corresponding to a name
+ * @fn uid_t ap_uname2id(const char *name)
+ */
+AP_DECLARE(uid_t) ap_uname2id(const char *name);
+#endif
+
+#ifdef HAVE_GETGRNAM
+/**
+ * Convert a group name to a numeric ID
+ * @param name The name to convert
+ * @return The group id corresponding to a name
+ * @fn gid_t ap_gname2id(const char *name)
+ */
+AP_DECLARE(gid_t) ap_gname2id(const char *name);
+#endif
+
+#ifndef HAVE_INITGROUPS
+/**
+ * The initgroups() function initializes the group access list by reading the
+ * group database /etc/group and using all groups of which user is a member.
+ * The additional group basegid is also added to the list.
+ * @param name The user name - must be non-NULL
+ * @param basegid The basegid to add
+ * @return returns 0 on success
+ * @fn int initgroups(const char *name, gid_t basegid)
+ */
+int initgroups(const char *name, gid_t basegid);
+#endif
+
+#if (!defined(WIN32) && !defined(NETWARE)) || defined(DOXYGEN)
+
+typedef struct ap_pod_t ap_pod_t;
+
+struct ap_pod_t {
+ apr_file_t *pod_in;
+ apr_file_t *pod_out;
+ apr_pool_t *p;
+};
+
+/**
+ * Open the pipe-of-death. The pipe of death is used to tell all child
+ * processes that it is time to die gracefully.
+ * @param p The pool to use for allocating the pipe
+ * @param pod the pipe-of-death that is created.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_pod_open(apr_pool_t *p, ap_pod_t **pod);
+
+/**
+ * Check the pipe to determine if the process has been signalled to die.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_pod_check(ap_pod_t *pod);
+
+/**
+ * Close the pipe-of-death
+ *
+ * @param pod the pipe-of-death to close.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_pod_close(ap_pod_t *pod);
+
+/**
+ * Write data to the pipe-of-death, signalling that one child process
+ * should die.
+ * @param pod the pipe-of-death to write to.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod);
+
+/**
+ * Write data to the pipe-of-death, signalling that all child process
+ * should die.
+ * @param pod The pipe-of-death to write to.
+ * @param num The number of child processes to kill
+ */
+AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num);
+
+#define AP_MPM_PODX_RESTART_CHAR '$'
+#define AP_MPM_PODX_GRACEFUL_CHAR '!'
+
+typedef enum { AP_MPM_PODX_NORESTART, AP_MPM_PODX_RESTART, AP_MPM_PODX_GRACEFUL } ap_podx_restart_t;
+
+/**
+ * Open the extended pipe-of-death.
+ * @param p The pool to use for allocating the pipe
+ * @param pod The pipe-of-death that is created.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_podx_open(apr_pool_t *p, ap_pod_t **pod);
+
+/**
+ * Check the extended pipe to determine if the process has been signalled to die.
+ */
+AP_DECLARE(int) ap_mpm_podx_check(ap_pod_t *pod);
+
+/**
+ * Close the pipe-of-death
+ *
+ * @param pod The pipe-of-death to close.
+ */
+AP_DECLARE(apr_status_t) ap_mpm_podx_close(ap_pod_t *pod);
+
+/**
+ * Write data to the extended pipe-of-death, signalling that one child process
+ * should die.
+ * @param pod the pipe-of-death to write to.
+ * @param graceful restart-type
+ */
+AP_DECLARE(apr_status_t) ap_mpm_podx_signal(ap_pod_t *pod,
+ ap_podx_restart_t graceful);
+
+/**
+ * Write data to the extended pipe-of-death, signalling that all child process
+ * should die.
+ * @param pod The pipe-of-death to write to.
+ * @param num The number of child processes to kill
+ * @param graceful restart-type
+ */
+AP_DECLARE(void) ap_mpm_podx_killpg(ap_pod_t *pod, int num,
+ ap_podx_restart_t graceful);
+
+#endif /* (!WIN32 && !NETWARE) || DOXYGEN */
+
+/**
+ * Check that exactly one MPM is loaded
+ * Returns NULL if yes, error string if not.
+ */
+AP_DECLARE(const char *) ap_check_mpm(void);
+
+/*
+ * These data members are common to all mpms. Each new mpm
+ * should either use the appropriate ap_mpm_set_* function
+ * in their command table or create their own for custom or
+ * OS specific needs. These should work for most.
+ */
+
+/**
+ * The maximum number of requests each child thread or
+ * process handles before dying off
+ */
+AP_DECLARE_DATA extern int ap_max_requests_per_child;
+const char *ap_mpm_set_max_requests(cmd_parms *cmd, void *dummy,
+ const char *arg);
+
+/**
+ * The filename used to store the process id.
+ */
+AP_DECLARE_DATA extern const char *ap_pid_fname;
+const char *ap_mpm_set_pidfile(cmd_parms *cmd, void *dummy,
+ const char *arg);
+void ap_mpm_dump_pidfile(apr_pool_t *p, apr_file_t *out);
+
+/*
+ * The directory that the server changes directory to dump core.
+ */
+AP_DECLARE_DATA extern char ap_coredump_dir[MAX_STRING_LEN];
+AP_DECLARE_DATA extern int ap_coredumpdir_configured;
+const char *ap_mpm_set_coredumpdir(cmd_parms *cmd, void *dummy,
+ const char *arg);
+
+/**
+ * Set the timeout period for a graceful shutdown.
+ */
+AP_DECLARE_DATA extern int ap_graceful_shutdown_timeout;
+AP_DECLARE(const char *)ap_mpm_set_graceful_shutdown(cmd_parms *cmd, void *dummy,
+ const char *arg);
+#define AP_GRACEFUL_SHUTDOWN_TIMEOUT_COMMAND \
+AP_INIT_TAKE1("GracefulShutdownTimeout", ap_mpm_set_graceful_shutdown, NULL, \
+ RSRC_CONF, "Maximum time in seconds to wait for child " \
+ "processes to complete transactions during shutdown")
+
+
+int ap_signal_server(int *, apr_pool_t *);
+void ap_mpm_rewrite_args(process_rec *);
+
+AP_DECLARE_DATA extern apr_uint32_t ap_max_mem_free;
+extern const char *ap_mpm_set_max_mem_free(cmd_parms *cmd, void *dummy,
+ const char *arg);
+
+AP_DECLARE_DATA extern apr_size_t ap_thread_stacksize;
+extern const char *ap_mpm_set_thread_stacksize(cmd_parms *cmd, void *dummy,
+ const char *arg);
+
+/* core's implementation of child_status hook */
+extern void ap_core_child_status(server_rec *s, pid_t pid, ap_generation_t gen,
+ int slot, mpm_child_status status);
+
+#if defined(AP_ENABLE_EXCEPTION_HOOK) && AP_ENABLE_EXCEPTION_HOOK
+extern const char *ap_mpm_set_exception_hook(cmd_parms *cmd, void *dummy,
+ const char *arg);
+#endif
+
+AP_DECLARE_HOOK(int,monitor,(apr_pool_t *p, server_rec *s))
+
+/* register modules that undertake to manage system security */
+AP_DECLARE(int) ap_sys_privileges_handlers(int inc);
+AP_DECLARE_HOOK(int, drop_privileges, (apr_pool_t * pchild, server_rec * s))
+
+/* implement the ap_mpm_query() function
+ * The MPM should return OK+APR_ENOTIMPL for any unimplemented query codes;
+ * modules which intercede for specific query codes should DECLINE for others.
+ */
+AP_DECLARE_HOOK(int, mpm_query, (int query_code, int *result, apr_status_t *rv))
+
+/* register the specified callback */
+AP_DECLARE_HOOK(apr_status_t, mpm_register_timed_callback,
+ (apr_time_t t, ap_mpm_callback_fn_t *cbfn, void *baton))
+
+/* get MPM name (e.g., "prefork" or "event") */
+AP_DECLARE_HOOK(const char *,mpm_get_name,(void))
+
+/**
+ * Notification that connection handling is suspending (disassociating from the
+ * current thread)
+ * @param c The current connection
+ * @param r The current request, or NULL if there is no active request
+ * @ingroup hooks
+ * @see ap_hook_resume_connection
+ * @note This hook is not implemented by MPMs like Prefork and Worker which
+ * handle all processing of a particular connection on the same thread.
+ * @note This hook will be called on the thread that was previously
+ * processing the connection.
+ * @note This hook is not called at the end of connection processing. This
+ * hook only notifies a module when processing of an active connection is
+ * suspended.
+ * @note Resumption and subsequent suspension of a connection solely to perform
+ * I/O by the MPM, with no execution of non-MPM code, may not necessarily result
+ * in a call to this hook.
+ */
+AP_DECLARE_HOOK(void, suspend_connection,
+ (conn_rec *c, request_rec *r))
+
+/**
+ * Notification that connection handling is resuming (associating with a thread)
+ * @param c The current connection
+ * @param r The current request, or NULL if there is no active request
+ * @ingroup hooks
+ * @see ap_hook_suspend_connection
+ * @note This hook is not implemented by MPMs like Prefork and Worker which
+ * handle all processing of a particular connection on the same thread.
+ * @note This hook will be called on the thread that will resume processing
+ * the connection.
+ * @note This hook is not called at the beginning of connection processing.
+ * This hook only notifies a module when processing resumes for a
+ * previously-suspended connection.
+ * @note Resumption and subsequent suspension of a connection solely to perform
+ * I/O by the MPM, with no execution of non-MPM code, may not necessarily result
+ * in a call to this hook.
+ */
+AP_DECLARE_HOOK(void, resume_connection,
+ (conn_rec *c, request_rec *r))
+
+/* mutex type string for accept mutex, if any; MPMs should use the
+ * same mutex type for ease of configuration
+ */
+#define AP_ACCEPT_MUTEX_TYPE "mpm-accept"
+
+/* internal pre-config logic for MPM-related settings, callable only from
+ * core's pre-config hook
+ */
+void mpm_common_pre_config(apr_pool_t *pconf);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !APACHE_MPM_COMMON_H */
+/** @} */
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