include/mpm_common.h

   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
  49 extern "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
  99 void 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
 116 void 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
 131 void 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
 144 int 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
 157 apr_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
 169 void 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
 181 int 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  */
 192 void 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  * @fn uid_t ap_uname2id(const char *name)
 203  */
 204 AP_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  * @fn gid_t ap_gname2id(const char *name)
 213  */
 214 AP_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 #ifdef AP_MPM_USES_POD
 220
 221 typedef struct ap_pod_t ap_pod_t;
 222
 223 struct ap_pod_t {
 224     apr_file_t *pod_in;
 225     apr_file_t *pod_out;
 226     apr_pool_t *p;
 227 };
 228
 229 /**
 230  * Open the pipe-of-death.  The pipe of death is used to tell all child
 231  * processes that it is time to die gracefully.
 232  * @param p The pool to use for allocating the pipe
 233  */
 234 AP_DECLARE(apr_status_t) ap_mpm_pod_open(apr_pool_t *p, ap_pod_t **pod);
 235
 236 /**
 237  * Check the pipe to determine if the process has been signalled to die.
 238  */
 239 AP_DECLARE(apr_status_t) ap_mpm_pod_check(ap_pod_t *pod);
 240
 241 /**
 242  * Close the pipe-of-death
 243  */
 244 AP_DECLARE(apr_status_t) ap_mpm_pod_close(ap_pod_t *pod);
 245
 246 /**
 247  * Write data to the pipe-of-death, signalling that one child process
 248  * should die.
 249  * @param p The pool to use when allocating any required structures.
 250  */
 251 AP_DECLARE(apr_status_t) ap_mpm_pod_signal(ap_pod_t *pod);
 252
 253 /**
 254  * Write data to the pipe-of-death, signalling that all child process
 255  * should die.
 256  * @param p The pool to use when allocating any required structures.
 257  * @param num The number of child processes to kill
 258  */
 259 AP_DECLARE(void) ap_mpm_pod_killpg(ap_pod_t *pod, int num);
 260 #endif
 261
 262 /*
 263  * These data members are common to all mpms. Each new mpm
 264  * should either use the appropriate ap_mpm_set_* function
 265  * in their command table or create their own for custom or
 266  * OS specific needs. These should work for most.
 267  */
 268
 269 /**
 270  * The maximum number of requests each child thread or
 271  * process handles before dying off
 272  */
 273 #ifdef AP_MPM_WANT_SET_MAX_REQUESTS
 274 extern int ap_max_requests_per_child;
 275 const char *ap_mpm_set_max_requests(cmd_parms *cmd, void *dummy,
 276                                     const char *arg);
 277 #endif
 278
 279 /**
 280  * The filename used to store the process id.
 281  */
 282 #ifdef AP_MPM_WANT_SET_PIDFILE
 283 extern const char *ap_pid_fname;
 284 const char *ap_mpm_set_pidfile(cmd_parms *cmd, void *dummy,
 285                                const char *arg);
 286 #endif
 287
 288 /**
 289  * The name of lockfile used when Apache needs to lock the accept() call.
 290  */
 291 #ifdef AP_MPM_WANT_SET_LOCKFILE
 292 extern const char *ap_lock_fname;
 293 const char *ap_mpm_set_lockfile(cmd_parms *cmd, void *dummy,
 294                                 const char *arg);
 295 #endif
 296
 297 /**
 298  * The system mutex implementation to use for the accept mutex.
 299  */
 300 #ifdef AP_MPM_WANT_SET_ACCEPT_LOCK_MECH
 301 extern apr_lockmech_e ap_accept_lock_mech;
 302 const char *ap_mpm_set_accept_lock_mech(cmd_parms *cmd, void *dummy,
 303                                         const char *arg);
 304 #endif
 305
 306 /*
 307  * Set the scorboard file.
 308  */
 309 #ifdef AP_MPM_WANT_SET_SCOREBOARD
 310 const char *ap_mpm_set_scoreboard(cmd_parms *cmd, void *dummy,
 311                                   const char *arg);
 312 #endif
 313
 314 /*
 315  * The directory that the server changes directory to dump core.
 316  */
 317 #ifdef AP_MPM_WANT_SET_COREDUMPDIR
 318 extern char ap_coredump_dir[MAX_STRING_LEN];
 319 extern int ap_coredumpdir_configured;
 320 const char *ap_mpm_set_coredumpdir(cmd_parms *cmd, void *dummy,
 321                                    const char *arg);
 322 #endif
 323
 324 /**
 325  * Set the timeout period for a graceful shutdown.
 326  */
 327 #ifdef AP_MPM_WANT_SET_GRACEFUL_SHUTDOWN
 328 extern int ap_graceful_shutdown_timeout;
 329 const char *ap_mpm_set_graceful_shutdown(cmd_parms *cmd, void *dummy,
 330                                          const char *arg);
 331 #define AP_GRACEFUL_SHUTDOWN_TIMEOUT_COMMAND \
 332 AP_INIT_TAKE1("GracefulShutdownTimeout", ap_mpm_set_graceful_shutdown, NULL, \
 333               RSRC_CONF, "Maximum time in seconds to wait for child "        \
 334               "processes to complete transactions during shutdown")
 335 #endif
 336
 337
 338 #ifdef AP_MPM_WANT_SIGNAL_SERVER
 339 int ap_signal_server(int *, apr_pool_t *);
 340 void ap_mpm_rewrite_args(process_rec *);
 341 #endif
 342
 343 #ifdef AP_MPM_WANT_SET_MAX_MEM_FREE
 344 extern apr_uint32_t ap_max_mem_free;
 345 extern const char *ap_mpm_set_max_mem_free(cmd_parms *cmd, void *dummy,
 346                                            const char *arg);
 347 #endif
 348
 349 #ifdef AP_MPM_WANT_SET_STACKSIZE
 350 extern apr_size_t ap_thread_stacksize;
 351 extern const char *ap_mpm_set_thread_stacksize(cmd_parms *cmd, void *dummy,
 352                                                const char *arg);
 353 #endif
 354
 355 #ifdef AP_MPM_WANT_FATAL_SIGNAL_HANDLER
 356 extern apr_status_t ap_fatal_signal_setup(server_rec *s, apr_pool_t *pconf);
 357 extern apr_status_t ap_fatal_signal_child_setup(server_rec *s);
 358 #endif
 359
 360 #if AP_ENABLE_EXCEPTION_HOOK
 361 extern const char *ap_mpm_set_exception_hook(cmd_parms *cmd, void *dummy,
 362                                              const char *arg);
 363 #endif
 364
 365 AP_DECLARE_HOOK(int,monitor,(apr_pool_t *p))
 366
 367 /* register modules that undertake to manage system security */
 368 AP_DECLARE(int) ap_sys_privileges_handlers(int inc);
 369 AP_DECLARE_HOOK(int, drop_privileges, (apr_pool_t * pchild, server_rec * s))
 370
 371 #ifdef __cplusplus
 372 }
 373 #endif
 374
 375 #endif /* !APACHE_MPM_COMMON_H */
 376 /** @} */