1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/* The purpose of this file is to store the code that MOST mpm's will need
18 * this does not mean a function only goes into this file if every MPM needs
19 * it.  It means that if a function is needed by more than one MPM, and
20 * future maintenance would be served by making the code common, then the
21 * function belongs here.
22 *
23 * This is going in src/main because it is not platform specific, it is
24 * specific to multi-process servers, but NOT to Unix.  Which is why it
25 * does not belong in src/os/unix
26 */
27
28/**
29 * @file  mpm_common.h
30 * @brief Multi-Processing Modules functions
31 *
32 * @defgroup APACHE_MPM Multi-Processing Modules
33 * @ingroup  APACHE
34 * @{
35 */
36
37#ifndef APACHE_MPM_COMMON_H
38#define APACHE_MPM_COMMON_H
39
40#include "ap_config.h"
41
42#if APR_HAVE_NETINET_TCP_H
43#include <netinet/tcp.h>    /* for TCP_NODELAY */
44#endif
45
46#include "mpm.h"
47
48#ifdef __cplusplus
49extern "C" {
50#endif
51
52/* The maximum length of the queue of pending connections, as defined
53 * by listen(2).  Under some systems, it should be increased if you
54 * are experiencing a heavy TCP SYN flood attack.
55 *
56 * It defaults to 511 instead of 512 because some systems store it
57 * as an 8-bit datatype; 512 truncated to 8-bits is 0, while 511 is
58 * 255 when truncated.
59 */
60#ifndef DEFAULT_LISTENBACKLOG
61#define DEFAULT_LISTENBACKLOG 511
62#endif
63
64/* Signal used to gracefully restart */
65#define AP_SIG_GRACEFUL SIGUSR1
66
67/* Signal used to gracefully restart (without SIG prefix) */
68#define AP_SIG_GRACEFUL_SHORT USR1
69
70/* Signal used to gracefully restart (as a quoted string) */
71#define AP_SIG_GRACEFUL_STRING "SIGUSR1"
72
73/* Signal used to gracefully stop */
74#define AP_SIG_GRACEFUL_STOP SIGWINCH
75
76/* Signal used to gracefully stop (without SIG prefix) */
77#define AP_SIG_GRACEFUL_STOP_SHORT WINCH
78
79/* Signal used to gracefully stop (as a quoted string) */
80#define AP_SIG_GRACEFUL_STOP_STRING "SIGWINCH"
81
82/**
83 * Make sure all child processes that have been spawned by the parent process
84 * have died.  This includes process registered as "other_children".
85 * @warning This is only defined if the MPM defines
86 *          AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
87 * @param terminate Either 1 or 0.  If 1, send the child processes SIGTERM
88 *        each time through the loop.  If 0, give the process time to die
89 *        on its own before signalling it.
90 * @tip This function requires that some macros are defined by the MPM: <pre>
91 *  MPM_CHILD_PID -- Get the pid from the specified spot in the scoreboard
92 *  MPM_NOTE_CHILD_KILLED -- Note the child died in the scoreboard
93 * </pre>
94 * @tip The MPM child processes which are reclaimed are those listed
95 * in the scoreboard as well as those currently registered via
96 * ap_register_extra_mpm_process().
97 */
98#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
99void ap_reclaim_child_processes(int terminate);
100#endif
101
102/**
103 * Catch any child processes that have been spawned by the parent process
104 * which have exited. This includes processes registered as "other_children".
105 * @warning This is only defined if the MPM defines
106 *          AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
107 * @tip This function requires that some macros are defined by the MPM: <pre>
108 *  MPM_CHILD_PID -- Get the pid from the specified spot in the scoreboard
109 *  MPM_NOTE_CHILD_KILLED -- Note the child died in the scoreboard
110 * </pre>
111 * @tip The MPM child processes which are relieved are those listed
112 * in the scoreboard as well as those currently registered via
113 * ap_register_extra_mpm_process().
114 */
115#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
116void ap_relieve_child_processes(void);
117#endif
118
119/**
120 * Tell ap_reclaim_child_processes() and ap_relieve_child_processes() about
121 * an MPM child process which has no entry in the scoreboard.
122 * @warning This is only defined if the MPM defines
123 *          AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
124 * @param pid The process id of an MPM child process which should be
125 * reclaimed when ap_reclaim_child_processes() is called.
126 * @tip If an extra MPM child process terminates prior to calling
127 * ap_reclaim_child_processes(), remove it from the list of such processes
128 * by calling ap_unregister_extra_mpm_process().
129 */
130#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
131void ap_register_extra_mpm_process(pid_t pid);
132#endif
133
134/**
135 * Unregister an MPM child process which was previously registered by a
136 * call to ap_register_extra_mpm_process().
137 * @warning This is only defined if the MPM defines
138 *          AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
139 * @param pid The process id of an MPM child process which no longer needs to
140 * be reclaimed.
141 * @return 1 if the process was found and removed, 0 otherwise
142 */
143#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
144int ap_unregister_extra_mpm_process(pid_t pid);
145#endif
146
147/**
148 * Safely signal an MPM child process, if the process is in the
149 * current process group.  Otherwise fail.
150 * @param pid the process id of a child process to signal
151 * @param sig the signal number to send
152 * @return APR_SUCCESS if signal is sent, otherwise an error as per kill(3);
153 * APR_EINVAL is returned if passed either an invalid (< 1) pid, or if
154 * the pid is not in the current process group
155 */
156#ifdef AP_MPM_WANT_RECLAIM_CHILD_PROCESSES
157apr_status_t ap_mpm_safe_kill(pid_t pid, int sig);
158#endif
159
160/**
161 * Determine if any child process has died.  If no child process died, then
162 * this process sleeps for the amount of time specified by the MPM defined
163 * macro SCOREBOARD_MAINTENANCE_INTERVAL.
164 * @param status The return code if a process has died
165 * @param ret The process id of the process that died
166 * @param p The pool to allocate out of
167 */
168#ifdef AP_MPM_WANT_WAIT_OR_TIMEOUT
169void ap_wait_or_timeout(apr_exit_why_e *status, int *exitcode, apr_proc_t *ret,
170                        apr_pool_t *p);
171#endif
172
173/**
174 * Log why a child died to the error log, if the child died without the
175 * parent signalling it.
176 * @param pid The child that has died
177 * @param status The status returned from ap_wait_or_timeout
178 * @return 0 on success, APEXIT_CHILDFATAL if MPM should terminate
179 */
180#ifdef AP_MPM_WANT_PROCESS_CHILD_STATUS
181int ap_process_child_status(apr_proc_t *pid, apr_exit_why_e why, int status);
182#endif
183
184#if defined(TCP_NODELAY) && !defined(MPE) && !defined(TPF)
185/**
186 * Turn off the nagle algorithm for the specified socket.  The nagle algorithm
187 * says that we should delay sending partial packets in the hopes of getting
188 * more data.  There are bad interactions between persistent connections and
189 * Nagle's algorithm that have severe performance penalties.
190 * @param s The socket to disable nagle for.
191 */
192void ap_sock_disable_nagle(apr_socket_t *s);
193#else
194#define ap_sock_disable_nagle(s)        /* NOOP */
195#endif
196
197#ifdef HAVE_GETPWNAM
198/**
199 * Convert a username to a numeric ID
200 * @param name The name to convert
201 * @return The user id corresponding to a name
202 * @deffunc uid_t ap_uname2id(const char *name)
203 */
204AP_DECLARE(uid_t) ap_uname2id(const char *name);
205#endif
206
207#ifdef HAVE_GETGRNAM
208/**
209 * Convert a group name to a numeric ID
210 * @param name The name to convert
211 * @return The group id corresponding to a name
212 * @deffunc gid_t ap_gname2id(const char *name)
213 */
214AP_DECLARE(gid_t) ap_gname2id(const char *name);
215#endif
216
217#define AP_MPM_HARD_LIMITS_FILE APACHE_MPM_DIR "/mpm_default.h"
218
219#ifndef HAVE_INITGROUPS
220/**
221 * The initgroups() function initializes the group access list by reading the
222 * group database /etc/group and using all groups of which user is a member.
223 * The additional group basegid is also added to the list.
224 * @param name The user name - must be non-NULL
225 * @param basegid The basegid to add
226 * @return returns 0 on success
227 * @fn int initgroups(const char *name, gid_t basegid)
228 */
229int initgroups(const char *name, gid_t basegid);
230#endif
231
232#ifdef AP_MPM_USES_POD
233
234typedef struct ap_pod_t ap_pod_t;
235
236struct ap_pod_t {
237    apr_file_t *pod_in;
238    apr_file_t *pod_out;
239    apr_pool_t *p;
240};
241
242/**
243 * Open the pipe-of-death.  The pipe of death is used to tell all child
244 * processes that it is time to die gracefully.
245 * @param p The pool to use for allocating the pipe
246 */
247AP_DECLARE(apr_status_t) ap_mpm_pod_open(apr_pool_t *p, ap_pod_t **pod);
248
249/**
250 * Check the pipe to determine if the process has been signalled to die.
251 */
252AP_DECLARE(apr_status_t) ap_mpm_pod_check(ap_pod_t *pod);
253
254/**
255 * Close the pipe-of-death
256 */
257AP_DECLARE(apr_status_t) ap_mpm_pod_close(ap_pod_t *pod);
258
259/**
260 * Write data to the pipe-of-death, signalling that one child process
261 * should die.
262 * @param p The pool to use when allocating any required structures.
263 */
264AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod);
265
266/**
267 * Write data to the pipe-of-death, signalling that all child process
268 * should die.
269 * @param p The pool to use when allocating any required structures.
270 * @param num The number of child processes to kill
271 */
272AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num);
273#endif
274
275/*
276 * These data members are common to all mpms. Each new mpm
277 * should either use the appropriate ap_mpm_set_* function
278 * in their command table or create their own for custom or
279 * OS specific needs. These should work for most.
280 */
281
282/**
283 * The maximum number of requests each child thread or
284 * process handles before dying off
285 */
286#ifdef AP_MPM_WANT_SET_MAX_REQUESTS
287extern int ap_max_requests_per_child;
288const char *ap_mpm_set_max_requests(cmd_parms *cmd, void *dummy,
289                                    const char *arg);
290#endif
291
292/**
293 * The filename used to store the process id.
294 */
295#ifdef AP_MPM_WANT_SET_PIDFILE
296extern const char *ap_pid_fname;
297const char *ap_mpm_set_pidfile(cmd_parms *cmd, void *dummy,
298                               const char *arg);
299#endif
300
301/**
302 * The name of lockfile used when Apache needs to lock the accept() call.
303 */
304#ifdef AP_MPM_WANT_SET_LOCKFILE
305extern const char *ap_lock_fname;
306const char *ap_mpm_set_lockfile(cmd_parms *cmd, void *dummy,
307                                const char *arg);
308#endif
309
310/**
311 * The system mutex implementation to use for the accept mutex.
312 */
313#ifdef AP_MPM_WANT_SET_ACCEPT_LOCK_MECH
314extern apr_lockmech_e ap_accept_lock_mech;
315extern const char ap_valid_accept_mutex_string[];
316const char *ap_mpm_set_accept_lock_mech(cmd_parms *cmd, void *dummy,
317                                        const char *arg);
318#endif
319
320/*
321 * Set the scorboard file.
322 */
323#ifdef AP_MPM_WANT_SET_SCOREBOARD
324const char *ap_mpm_set_scoreboard(cmd_parms *cmd, void *dummy,
325                                  const char *arg);
326#endif
327
328/*
329 * The directory that the server changes directory to dump core.
330 */
331#ifdef AP_MPM_WANT_SET_COREDUMPDIR
332extern char ap_coredump_dir[MAX_STRING_LEN];
333extern int ap_coredumpdir_configured;
334const char *ap_mpm_set_coredumpdir(cmd_parms *cmd, void *dummy,
335                                   const char *arg);
336#endif
337
338/**
339 * Set the timeout period for a graceful shutdown.
340 */
341#ifdef AP_MPM_WANT_SET_GRACEFUL_SHUTDOWN
342extern int ap_graceful_shutdown_timeout;
343const char *ap_mpm_set_graceful_shutdown(cmd_parms *cmd, void *dummy,
344                                         const char *arg);
345#define AP_GRACEFUL_SHUTDOWN_TIMEOUT_COMMAND \
346AP_INIT_TAKE1("GracefulShutdownTimeout", ap_mpm_set_graceful_shutdown, NULL, \
347              RSRC_CONF, "Maximum time in seconds to wait for child "        \
348              "processes to complete transactions during shutdown")
349#endif
350
351
352#ifdef AP_MPM_WANT_SIGNAL_SERVER
353int ap_signal_server(int *, apr_pool_t *);
354void ap_mpm_rewrite_args(process_rec *);
355#endif
356
357#ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
358extern apr_uint32_t ap_max_mem_free;
359extern const char *ap_mpm_set_max_mem_free(cmd_parms *cmd, void *dummy,
360                                           const char *arg);
361#endif
362
363#ifdef AP_MPM_WANT_SET_STACKSIZE
364extern apr_size_t ap_thread_stacksize;
365extern const char *ap_mpm_set_thread_stacksize(cmd_parms *cmd, void *dummy,
366                                               const char *arg);
367#endif
368
369#ifdef AP_MPM_WANT_FATAL_SIGNAL_HANDLER
370extern apr_status_t ap_fatal_signal_setup(server_rec *s, apr_pool_t *pconf);
371extern apr_status_t ap_fatal_signal_child_setup(server_rec *s);
372#endif
373
374#if AP_ENABLE_EXCEPTION_HOOK
375extern const char *ap_mpm_set_exception_hook(cmd_parms *cmd, void *dummy,
376                                             const char *arg);
377#endif
378
379AP_DECLARE_HOOK(int,monitor,(apr_pool_t *p))
380
381#ifdef __cplusplus
382}
383#endif
384
385#endif /* !APACHE_MPM_COMMON_H */
386/** @} */
387