Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * launch_backend.c
4 : * Functions for launching backends and other postmaster child
5 : * processes.
6 : *
7 : * On Unix systems, a new child process is launched with fork(). It inherits
8 : * all the global variables and data structures that had been initialized in
9 : * the postmaster. After forking, the child process closes the file
10 : * descriptors that are not needed in the child process, and sets up the
11 : * mechanism to detect death of the parent postmaster process, etc. After
12 : * that, it calls the right Main function depending on the kind of child
13 : * process.
14 : *
15 : * In EXEC_BACKEND mode, which is used on Windows but can be enabled on other
16 : * platforms for testing, the child process is launched by fork() + exec() (or
17 : * CreateProcess() on Windows). It does not inherit the state from the
18 : * postmaster, so it needs to re-attach to the shared memory, re-initialize
19 : * global variables, reload the config file etc. to get the process to the
20 : * same state as after fork() on a Unix system.
21 : *
22 : *
23 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
24 : * Portions Copyright (c) 1994, Regents of the University of California
25 : *
26 : * IDENTIFICATION
27 : * src/backend/postmaster/launch_backend.c
28 : *
29 : *-------------------------------------------------------------------------
30 : */
31 :
32 : #include "postgres.h"
33 :
34 : #include <unistd.h>
35 :
36 : #include "access/xlog.h"
37 : #include "common/file_utils.h"
38 : #include "libpq/libpq-be.h"
39 : #include "libpq/pqsignal.h"
40 : #include "miscadmin.h"
41 : #include "nodes/queryjumble.h"
42 : #include "port.h"
43 : #include "postmaster/autovacuum.h"
44 : #include "postmaster/auxprocess.h"
45 : #include "postmaster/bgworker_internals.h"
46 : #include "postmaster/bgwriter.h"
47 : #include "postmaster/fork_process.h"
48 : #include "postmaster/pgarch.h"
49 : #include "postmaster/postmaster.h"
50 : #include "postmaster/startup.h"
51 : #include "postmaster/syslogger.h"
52 : #include "postmaster/walsummarizer.h"
53 : #include "postmaster/walwriter.h"
54 : #include "replication/slotsync.h"
55 : #include "replication/walreceiver.h"
56 : #include "storage/fd.h"
57 : #include "storage/ipc.h"
58 : #include "storage/pg_shmem.h"
59 : #include "storage/pmsignal.h"
60 : #include "storage/proc.h"
61 : #include "tcop/backend_startup.h"
62 : #include "tcop/tcopprot.h"
63 : #include "utils/builtins.h"
64 : #include "utils/datetime.h"
65 : #include "utils/guc.h"
66 : #include "utils/memutils.h"
67 : #include "utils/timestamp.h"
68 :
69 : #ifdef EXEC_BACKEND
70 : #include "nodes/queryjumble.h"
71 : #include "storage/pg_shmem.h"
72 : #include "storage/spin.h"
73 : #endif
74 :
75 :
76 : #ifdef EXEC_BACKEND
77 :
78 : /* Type for a socket that can be inherited to a client process */
79 : #ifdef WIN32
80 : typedef struct
81 : {
82 : SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET
83 : * if not a socket */
84 : WSAPROTOCOL_INFO wsainfo;
85 : } InheritableSocket;
86 : #else
87 : typedef int InheritableSocket;
88 : #endif
89 :
90 : /*
91 : * Structure contains all variables passed to exec:ed backends
92 : */
93 : typedef struct
94 : {
95 : char DataDir[MAXPGPATH];
96 : int32 MyCancelKey;
97 : int MyPMChildSlot;
98 : #ifndef WIN32
99 : unsigned long UsedShmemSegID;
100 : #else
101 : void *ShmemProtectiveRegion;
102 : HANDLE UsedShmemSegID;
103 : #endif
104 : void *UsedShmemSegAddr;
105 : slock_t *ShmemLock;
106 : struct bkend *ShmemBackendArray;
107 : #ifndef HAVE_SPINLOCKS
108 : PGSemaphore *SpinlockSemaArray;
109 : #endif
110 : int NamedLWLockTrancheRequests;
111 : NamedLWLockTranche *NamedLWLockTrancheArray;
112 : LWLockPadded *MainLWLockArray;
113 : slock_t *ProcStructLock;
114 : PROC_HDR *ProcGlobal;
115 : PGPROC *AuxiliaryProcs;
116 : PGPROC *PreparedXactProcs;
117 : PMSignalData *PMSignalState;
118 : pid_t PostmasterPid;
119 : TimestampTz PgStartTime;
120 : TimestampTz PgReloadTime;
121 : pg_time_t first_syslogger_file_time;
122 : bool redirection_done;
123 : bool IsBinaryUpgrade;
124 : bool query_id_enabled;
125 : int max_safe_fds;
126 : int MaxBackends;
127 : #ifdef WIN32
128 : HANDLE PostmasterHandle;
129 : HANDLE initial_signal_pipe;
130 : HANDLE syslogPipe[2];
131 : #else
132 : int postmaster_alive_fds[2];
133 : int syslogPipe[2];
134 : #endif
135 : char my_exec_path[MAXPGPATH];
136 : char pkglib_path[MAXPGPATH];
137 :
138 : /*
139 : * These are only used by backend processes, but are here because passing
140 : * a socket needs some special handling on Windows. 'client_sock' is an
141 : * explicit argument to postmaster_child_launch, but is stored in
142 : * MyClientSocket in the child process.
143 : */
144 : ClientSocket client_sock;
145 : InheritableSocket inh_sock;
146 :
147 : /*
148 : * Extra startup data, content depends on the child process.
149 : */
150 : size_t startup_data_len;
151 : char startup_data[FLEXIBLE_ARRAY_MEMBER];
152 : } BackendParameters;
153 :
154 : #define SizeOfBackendParameters(startup_data_len) (offsetof(BackendParameters, startup_data) + startup_data_len)
155 :
156 : static void read_backend_variables(char *id, char **startup_data, size_t *startup_data_len);
157 : static void restore_backend_variables(BackendParameters *param);
158 :
159 : static bool save_backend_variables(BackendParameters *param, ClientSocket *client_sock,
160 : #ifdef WIN32
161 : HANDLE childProcess, pid_t childPid,
162 : #endif
163 : char *startup_data, size_t startup_data_len);
164 :
165 : static pid_t internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock);
166 :
167 : #endif /* EXEC_BACKEND */
168 :
169 : /*
170 : * Information needed to launch different kinds of child processes.
171 : */
172 : typedef struct
173 : {
174 : const char *name;
175 : void (*main_fn) (char *startup_data, size_t startup_data_len) pg_attribute_noreturn();
176 : bool shmem_attach;
177 : } child_process_kind;
178 :
179 : child_process_kind child_process_kinds[] = {
180 : [B_INVALID] = {"invalid", NULL, false},
181 :
182 : [B_BACKEND] = {"backend", BackendMain, true},
183 : [B_AUTOVAC_LAUNCHER] = {"autovacuum launcher", AutoVacLauncherMain, true},
184 : [B_AUTOVAC_WORKER] = {"autovacuum worker", AutoVacWorkerMain, true},
185 : [B_BG_WORKER] = {"bgworker", BackgroundWorkerMain, true},
186 :
187 : /*
188 : * WAL senders start their life as regular backend processes, and change
189 : * their type after authenticating the client for replication. We list it
190 : * here for PostmasterChildName() but cannot launch them directly.
191 : */
192 : [B_WAL_SENDER] = {"wal sender", NULL, true},
193 : [B_SLOTSYNC_WORKER] = {"slot sync worker", ReplSlotSyncWorkerMain, true},
194 :
195 : [B_STANDALONE_BACKEND] = {"standalone backend", NULL, false},
196 :
197 : [B_ARCHIVER] = {"archiver", PgArchiverMain, true},
198 : [B_BG_WRITER] = {"bgwriter", BackgroundWriterMain, true},
199 : [B_CHECKPOINTER] = {"checkpointer", CheckpointerMain, true},
200 : [B_STARTUP] = {"startup", StartupProcessMain, true},
201 : [B_WAL_RECEIVER] = {"wal_receiver", WalReceiverMain, true},
202 : [B_WAL_SUMMARIZER] = {"wal_summarizer", WalSummarizerMain, true},
203 : [B_WAL_WRITER] = {"wal_writer", WalWriterMain, true},
204 :
205 : [B_LOGGER] = {"syslogger", SysLoggerMain, false},
206 : };
207 :
208 : const char *
209 0 : PostmasterChildName(BackendType child_type)
210 : {
211 0 : return child_process_kinds[child_type].name;
212 : }
213 :
214 : /*
215 : * Start a new postmaster child process.
216 : *
217 : * The child process will be restored to roughly the same state whether
218 : * EXEC_BACKEND is used or not: it will be attached to shared memory, and fds
219 : * and other resources that we've inherited from postmaster that are not
220 : * needed in a child process have been closed.
221 : *
222 : * 'startup_data' is an optional contiguous chunk of data that is passed to
223 : * the child process.
224 : */
225 : pid_t
226 33194 : postmaster_child_launch(BackendType child_type,
227 : char *startup_data, size_t startup_data_len,
228 : ClientSocket *client_sock)
229 : {
230 : pid_t pid;
231 :
232 : Assert(IsPostmasterEnvironment && !IsUnderPostmaster);
233 :
234 : #ifdef EXEC_BACKEND
235 : pid = internal_forkexec(child_process_kinds[child_type].name,
236 : startup_data, startup_data_len, client_sock);
237 : /* the child process will arrive in SubPostmasterMain */
238 : #else /* !EXEC_BACKEND */
239 33194 : pid = fork_process();
240 63126 : if (pid == 0) /* child */
241 : {
242 : /* Close the postmaster's sockets */
243 29938 : ClosePostmasterPorts(child_type == B_LOGGER);
244 :
245 : /* Detangle from postmaster */
246 29938 : InitPostmasterChild();
247 :
248 : /*
249 : * Enter the Main function with TopMemoryContext. The startup data is
250 : * allocated in PostmasterContext, so we cannot release it here yet.
251 : * The Main function will do it after it's done handling the startup
252 : * data.
253 : */
254 29938 : MemoryContextSwitchTo(TopMemoryContext);
255 :
256 29938 : if (client_sock)
257 : {
258 21026 : MyClientSocket = palloc(sizeof(ClientSocket));
259 21026 : memcpy(MyClientSocket, client_sock, sizeof(ClientSocket));
260 : }
261 :
262 : /*
263 : * Run the appropriate Main function
264 : */
265 29938 : child_process_kinds[child_type].main_fn(startup_data, startup_data_len);
266 : pg_unreachable(); /* main_fn never returns */
267 : }
268 : #endif /* EXEC_BACKEND */
269 33188 : return pid;
270 : }
271 :
272 : #ifdef EXEC_BACKEND
273 : #ifndef WIN32
274 :
275 : /*
276 : * internal_forkexec non-win32 implementation
277 : *
278 : * - writes out backend variables to the parameter file
279 : * - fork():s, and then exec():s the child process
280 : */
281 : static pid_t
282 : internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock)
283 : {
284 : static unsigned long tmpBackendFileNum = 0;
285 : pid_t pid;
286 : char tmpfilename[MAXPGPATH];
287 : size_t paramsz;
288 : BackendParameters *param;
289 : FILE *fp;
290 : char *argv[4];
291 : char forkav[MAXPGPATH];
292 :
293 : /*
294 : * Use palloc0 to make sure padding bytes are initialized, to prevent
295 : * Valgrind from complaining about writing uninitialized bytes to the
296 : * file. This isn't performance critical, and the win32 implementation
297 : * initializes the padding bytes to zeros, so do it even when not using
298 : * Valgrind.
299 : */
300 : paramsz = SizeOfBackendParameters(startup_data_len);
301 : param = palloc0(paramsz);
302 : if (!save_backend_variables(param, client_sock, startup_data, startup_data_len))
303 : {
304 : pfree(param);
305 : return -1; /* log made by save_backend_variables */
306 : }
307 :
308 : /* Calculate name for temp file */
309 : snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu",
310 : PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
311 : MyProcPid, ++tmpBackendFileNum);
312 :
313 : /* Open file */
314 : fp = AllocateFile(tmpfilename, PG_BINARY_W);
315 : if (!fp)
316 : {
317 : /*
318 : * As in OpenTemporaryFileInTablespace, try to make the temp-file
319 : * directory, ignoring errors.
320 : */
321 : (void) MakePGDirectory(PG_TEMP_FILES_DIR);
322 :
323 : fp = AllocateFile(tmpfilename, PG_BINARY_W);
324 : if (!fp)
325 : {
326 : ereport(LOG,
327 : (errcode_for_file_access(),
328 : errmsg("could not create file \"%s\": %m",
329 : tmpfilename)));
330 : pfree(param);
331 : return -1;
332 : }
333 : }
334 :
335 : if (fwrite(param, paramsz, 1, fp) != 1)
336 : {
337 : ereport(LOG,
338 : (errcode_for_file_access(),
339 : errmsg("could not write to file \"%s\": %m", tmpfilename)));
340 : FreeFile(fp);
341 : pfree(param);
342 : return -1;
343 : }
344 : pfree(param);
345 :
346 : /* Release file */
347 : if (FreeFile(fp))
348 : {
349 : ereport(LOG,
350 : (errcode_for_file_access(),
351 : errmsg("could not write to file \"%s\": %m", tmpfilename)));
352 : return -1;
353 : }
354 :
355 : /* set up argv properly */
356 : argv[0] = "postgres";
357 : snprintf(forkav, MAXPGPATH, "--forkchild=%s", child_kind);
358 : argv[1] = forkav;
359 : /* Insert temp file name after --forkchild argument */
360 : argv[2] = tmpfilename;
361 : argv[3] = NULL;
362 :
363 : /* Fire off execv in child */
364 : if ((pid = fork_process()) == 0)
365 : {
366 : if (execv(postgres_exec_path, argv) < 0)
367 : {
368 : ereport(LOG,
369 : (errmsg("could not execute server process \"%s\": %m",
370 : postgres_exec_path)));
371 : /* We're already in the child process here, can't return */
372 : exit(1);
373 : }
374 : }
375 :
376 : return pid; /* Parent returns pid, or -1 on fork failure */
377 : }
378 : #else /* WIN32 */
379 :
380 : /*
381 : * internal_forkexec win32 implementation
382 : *
383 : * - starts backend using CreateProcess(), in suspended state
384 : * - writes out backend variables to the parameter file
385 : * - during this, duplicates handles and sockets required for
386 : * inheritance into the new process
387 : * - resumes execution of the new process once the backend parameter
388 : * file is complete.
389 : */
390 : static pid_t
391 : internal_forkexec(const char *child_kind, char *startup_data, size_t startup_data_len, ClientSocket *client_sock)
392 : {
393 : int retry_count = 0;
394 : STARTUPINFO si;
395 : PROCESS_INFORMATION pi;
396 : char cmdLine[MAXPGPATH * 2];
397 : HANDLE paramHandle;
398 : BackendParameters *param;
399 : SECURITY_ATTRIBUTES sa;
400 : size_t paramsz;
401 : char paramHandleStr[32];
402 : int l;
403 :
404 : paramsz = SizeOfBackendParameters(startup_data_len);
405 :
406 : /* Resume here if we need to retry */
407 : retry:
408 :
409 : /* Set up shared memory for parameter passing */
410 : ZeroMemory(&sa, sizeof(sa));
411 : sa.nLength = sizeof(sa);
412 : sa.bInheritHandle = TRUE;
413 : paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE,
414 : &sa,
415 : PAGE_READWRITE,
416 : 0,
417 : paramsz,
418 : NULL);
419 : if (paramHandle == INVALID_HANDLE_VALUE)
420 : {
421 : ereport(LOG,
422 : (errmsg("could not create backend parameter file mapping: error code %lu",
423 : GetLastError())));
424 : return -1;
425 : }
426 : param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, paramsz);
427 : if (!param)
428 : {
429 : ereport(LOG,
430 : (errmsg("could not map backend parameter memory: error code %lu",
431 : GetLastError())));
432 : CloseHandle(paramHandle);
433 : return -1;
434 : }
435 :
436 : /* Format the cmd line */
437 : #ifdef _WIN64
438 : sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle);
439 : #else
440 : sprintf(paramHandleStr, "%lu", (DWORD) paramHandle);
441 : #endif
442 : l = snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\" --forkchild=\"%s\" %s",
443 : postgres_exec_path, child_kind, paramHandleStr);
444 : if (l >= sizeof(cmdLine))
445 : {
446 : ereport(LOG,
447 : (errmsg("subprocess command line too long")));
448 : UnmapViewOfFile(param);
449 : CloseHandle(paramHandle);
450 : return -1;
451 : }
452 :
453 : memset(&pi, 0, sizeof(pi));
454 : memset(&si, 0, sizeof(si));
455 : si.cb = sizeof(si);
456 :
457 : /*
458 : * Create the subprocess in a suspended state. This will be resumed later,
459 : * once we have written out the parameter file.
460 : */
461 : if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED,
462 : NULL, NULL, &si, &pi))
463 : {
464 : ereport(LOG,
465 : (errmsg("CreateProcess() call failed: %m (error code %lu)",
466 : GetLastError())));
467 : UnmapViewOfFile(param);
468 : CloseHandle(paramHandle);
469 : return -1;
470 : }
471 :
472 : if (!save_backend_variables(param, client_sock, pi.hProcess, pi.dwProcessId, startup_data, startup_data_len))
473 : {
474 : /*
475 : * log made by save_backend_variables, but we have to clean up the
476 : * mess with the half-started process
477 : */
478 : if (!TerminateProcess(pi.hProcess, 255))
479 : ereport(LOG,
480 : (errmsg_internal("could not terminate unstarted process: error code %lu",
481 : GetLastError())));
482 : CloseHandle(pi.hProcess);
483 : CloseHandle(pi.hThread);
484 : UnmapViewOfFile(param);
485 : CloseHandle(paramHandle);
486 : return -1; /* log made by save_backend_variables */
487 : }
488 :
489 : /* Drop the parameter shared memory that is now inherited to the backend */
490 : if (!UnmapViewOfFile(param))
491 : ereport(LOG,
492 : (errmsg("could not unmap view of backend parameter file: error code %lu",
493 : GetLastError())));
494 : if (!CloseHandle(paramHandle))
495 : ereport(LOG,
496 : (errmsg("could not close handle to backend parameter file: error code %lu",
497 : GetLastError())));
498 :
499 : /*
500 : * Reserve the memory region used by our main shared memory segment before
501 : * we resume the child process. Normally this should succeed, but if ASLR
502 : * is active then it might sometimes fail due to the stack or heap having
503 : * gotten mapped into that range. In that case, just terminate the
504 : * process and retry.
505 : */
506 : if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess))
507 : {
508 : /* pgwin32_ReserveSharedMemoryRegion already made a log entry */
509 : if (!TerminateProcess(pi.hProcess, 255))
510 : ereport(LOG,
511 : (errmsg_internal("could not terminate process that failed to reserve memory: error code %lu",
512 : GetLastError())));
513 : CloseHandle(pi.hProcess);
514 : CloseHandle(pi.hThread);
515 : if (++retry_count < 100)
516 : goto retry;
517 : ereport(LOG,
518 : (errmsg("giving up after too many tries to reserve shared memory"),
519 : errhint("This might be caused by ASLR or antivirus software.")));
520 : return -1;
521 : }
522 :
523 : /*
524 : * Now that the backend variables are written out, we start the child
525 : * thread so it can start initializing while we set up the rest of the
526 : * parent state.
527 : */
528 : if (ResumeThread(pi.hThread) == -1)
529 : {
530 : if (!TerminateProcess(pi.hProcess, 255))
531 : {
532 : ereport(LOG,
533 : (errmsg_internal("could not terminate unstartable process: error code %lu",
534 : GetLastError())));
535 : CloseHandle(pi.hProcess);
536 : CloseHandle(pi.hThread);
537 : return -1;
538 : }
539 : CloseHandle(pi.hProcess);
540 : CloseHandle(pi.hThread);
541 : ereport(LOG,
542 : (errmsg_internal("could not resume thread of unstarted process: error code %lu",
543 : GetLastError())));
544 : return -1;
545 : }
546 :
547 : /* Set up notification when the child process dies */
548 : pgwin32_register_deadchild_callback(pi.hProcess, pi.dwProcessId);
549 :
550 : /* Don't close pi.hProcess, it's owned by the deadchild callback now */
551 :
552 : CloseHandle(pi.hThread);
553 :
554 : return pi.dwProcessId;
555 : }
556 : #endif /* WIN32 */
557 :
558 : /*
559 : * SubPostmasterMain -- Get the fork/exec'd process into a state equivalent
560 : * to what it would be if we'd simply forked on Unix, and then
561 : * dispatch to the appropriate place.
562 : *
563 : * The first two command line arguments are expected to be "--forkchild=<name>",
564 : * where <name> indicates which postmaster child we are to become, and
565 : * the name of a variables file that we can read to load data that would
566 : * have been inherited by fork() on Unix.
567 : */
568 : void
569 : SubPostmasterMain(int argc, char *argv[])
570 : {
571 : char *startup_data;
572 : size_t startup_data_len;
573 : char *child_kind;
574 : BackendType child_type;
575 : bool found = false;
576 :
577 : /* In EXEC_BACKEND case we will not have inherited these settings */
578 : IsPostmasterEnvironment = true;
579 : whereToSendOutput = DestNone;
580 :
581 : /* Setup essential subsystems (to ensure elog() behaves sanely) */
582 : InitializeGUCOptions();
583 :
584 : /* Check we got appropriate args */
585 : if (argc != 3)
586 : elog(FATAL, "invalid subpostmaster invocation");
587 :
588 : /* Find the entry in child_process_kinds */
589 : if (strncmp(argv[1], "--forkchild=", 12) != 0)
590 : elog(FATAL, "invalid subpostmaster invocation (--forkchild argument missing)");
591 : child_kind = argv[1] + 12;
592 : found = false;
593 : for (int idx = 0; idx < lengthof(child_process_kinds); idx++)
594 : {
595 : if (strcmp(child_process_kinds[idx].name, child_kind) == 0)
596 : {
597 : child_type = (BackendType) idx;
598 : found = true;
599 : break;
600 : }
601 : }
602 : if (!found)
603 : elog(ERROR, "unknown child kind %s", child_kind);
604 :
605 : /* Read in the variables file */
606 : read_backend_variables(argv[2], &startup_data, &startup_data_len);
607 :
608 : /* Close the postmaster's sockets (as soon as we know them) */
609 : ClosePostmasterPorts(child_type == B_LOGGER);
610 :
611 : /* Setup as postmaster child */
612 : InitPostmasterChild();
613 :
614 : /*
615 : * If appropriate, physically re-attach to shared memory segment. We want
616 : * to do this before going any further to ensure that we can attach at the
617 : * same address the postmaster used. On the other hand, if we choose not
618 : * to re-attach, we may have other cleanup to do.
619 : *
620 : * If testing EXEC_BACKEND on Linux, you should run this as root before
621 : * starting the postmaster:
622 : *
623 : * sysctl -w kernel.randomize_va_space=0
624 : *
625 : * This prevents using randomized stack and code addresses that cause the
626 : * child process's memory map to be different from the parent's, making it
627 : * sometimes impossible to attach to shared memory at the desired address.
628 : * Return the setting to its old value (usually '1' or '2') when finished.
629 : */
630 : if (child_process_kinds[child_type].shmem_attach)
631 : PGSharedMemoryReAttach();
632 : else
633 : PGSharedMemoryNoReAttach();
634 :
635 : /* Read in remaining GUC variables */
636 : read_nondefault_variables();
637 :
638 : /*
639 : * Check that the data directory looks valid, which will also check the
640 : * privileges on the data directory and update our umask and file/group
641 : * variables for creating files later. Note: this should really be done
642 : * before we create any files or directories.
643 : */
644 : checkDataDir();
645 :
646 : /*
647 : * (re-)read control file, as it contains config. The postmaster will
648 : * already have read this, but this process doesn't know about that.
649 : */
650 : LocalProcessControlFile(false);
651 :
652 : /*
653 : * Reload any libraries that were preloaded by the postmaster. Since we
654 : * exec'd this process, those libraries didn't come along with us; but we
655 : * should load them into all child processes to be consistent with the
656 : * non-EXEC_BACKEND behavior.
657 : */
658 : process_shared_preload_libraries();
659 :
660 : /* Restore basic shared memory pointers */
661 : if (UsedShmemSegAddr != NULL)
662 : InitShmemAccess(UsedShmemSegAddr);
663 :
664 : /*
665 : * Run the appropriate Main function
666 : */
667 : child_process_kinds[child_type].main_fn(startup_data, startup_data_len);
668 : pg_unreachable(); /* main_fn never returns */
669 : }
670 :
671 : /*
672 : * The following need to be available to the save/restore_backend_variables
673 : * functions. They are marked NON_EXEC_STATIC in their home modules.
674 : */
675 : extern slock_t *ShmemLock;
676 : extern slock_t *ProcStructLock;
677 : extern PGPROC *AuxiliaryProcs;
678 : extern PMSignalData *PMSignalState;
679 : extern pg_time_t first_syslogger_file_time;
680 : extern struct bkend *ShmemBackendArray;
681 : extern bool redirection_done;
682 :
683 : #ifndef WIN32
684 : #define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true)
685 : #define read_inheritable_socket(dest, src) (*(dest) = *(src))
686 : #else
687 : static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child);
688 : static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src,
689 : pid_t childPid);
690 : static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src);
691 : #endif
692 :
693 :
694 : /* Save critical backend variables into the BackendParameters struct */
695 : static bool
696 : save_backend_variables(BackendParameters *param, ClientSocket *client_sock,
697 : #ifdef WIN32
698 : HANDLE childProcess, pid_t childPid,
699 : #endif
700 : char *startup_data, size_t startup_data_len)
701 : {
702 : if (client_sock)
703 : memcpy(¶m->client_sock, client_sock, sizeof(ClientSocket));
704 : else
705 : memset(¶m->client_sock, 0, sizeof(ClientSocket));
706 : if (!write_inheritable_socket(¶m->inh_sock,
707 : client_sock ? client_sock->sock : PGINVALID_SOCKET,
708 : childPid))
709 : return false;
710 :
711 : strlcpy(param->DataDir, DataDir, MAXPGPATH);
712 :
713 : param->MyCancelKey = MyCancelKey;
714 : param->MyPMChildSlot = MyPMChildSlot;
715 :
716 : #ifdef WIN32
717 : param->ShmemProtectiveRegion = ShmemProtectiveRegion;
718 : #endif
719 : param->UsedShmemSegID = UsedShmemSegID;
720 : param->UsedShmemSegAddr = UsedShmemSegAddr;
721 :
722 : param->ShmemLock = ShmemLock;
723 : param->ShmemBackendArray = ShmemBackendArray;
724 :
725 : #ifndef HAVE_SPINLOCKS
726 : param->SpinlockSemaArray = SpinlockSemaArray;
727 : #endif
728 : param->NamedLWLockTrancheRequests = NamedLWLockTrancheRequests;
729 : param->NamedLWLockTrancheArray = NamedLWLockTrancheArray;
730 : param->MainLWLockArray = MainLWLockArray;
731 : param->ProcStructLock = ProcStructLock;
732 : param->ProcGlobal = ProcGlobal;
733 : param->AuxiliaryProcs = AuxiliaryProcs;
734 : param->PreparedXactProcs = PreparedXactProcs;
735 : param->PMSignalState = PMSignalState;
736 :
737 : param->PostmasterPid = PostmasterPid;
738 : param->PgStartTime = PgStartTime;
739 : param->PgReloadTime = PgReloadTime;
740 : param->first_syslogger_file_time = first_syslogger_file_time;
741 :
742 : param->redirection_done = redirection_done;
743 : param->IsBinaryUpgrade = IsBinaryUpgrade;
744 : param->query_id_enabled = query_id_enabled;
745 : param->max_safe_fds = max_safe_fds;
746 :
747 : param->MaxBackends = MaxBackends;
748 :
749 : #ifdef WIN32
750 : param->PostmasterHandle = PostmasterHandle;
751 : if (!write_duplicated_handle(¶m->initial_signal_pipe,
752 : pgwin32_create_signal_listener(childPid),
753 : childProcess))
754 : return false;
755 : #else
756 : memcpy(¶m->postmaster_alive_fds, &postmaster_alive_fds,
757 : sizeof(postmaster_alive_fds));
758 : #endif
759 :
760 : memcpy(¶m->syslogPipe, &syslogPipe, sizeof(syslogPipe));
761 :
762 : strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH);
763 :
764 : strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH);
765 :
766 : param->startup_data_len = startup_data_len;
767 : memcpy(param->startup_data, startup_data, startup_data_len);
768 :
769 : return true;
770 : }
771 :
772 : #ifdef WIN32
773 : /*
774 : * Duplicate a handle for usage in a child process, and write the child
775 : * process instance of the handle to the parameter file.
776 : */
777 : static bool
778 : write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess)
779 : {
780 : HANDLE hChild = INVALID_HANDLE_VALUE;
781 :
782 : if (!DuplicateHandle(GetCurrentProcess(),
783 : src,
784 : childProcess,
785 : &hChild,
786 : 0,
787 : TRUE,
788 : DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
789 : {
790 : ereport(LOG,
791 : (errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu",
792 : GetLastError())));
793 : return false;
794 : }
795 :
796 : *dest = hChild;
797 : return true;
798 : }
799 :
800 : /*
801 : * Duplicate a socket for usage in a child process, and write the resulting
802 : * structure to the parameter file.
803 : * This is required because a number of LSPs (Layered Service Providers) very
804 : * common on Windows (antivirus, firewalls, download managers etc) break
805 : * straight socket inheritance.
806 : */
807 : static bool
808 : write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid)
809 : {
810 : dest->origsocket = src;
811 : if (src != 0 && src != PGINVALID_SOCKET)
812 : {
813 : /* Actual socket */
814 : if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0)
815 : {
816 : ereport(LOG,
817 : (errmsg("could not duplicate socket %d for use in backend: error code %d",
818 : (int) src, WSAGetLastError())));
819 : return false;
820 : }
821 : }
822 : return true;
823 : }
824 :
825 : /*
826 : * Read a duplicate socket structure back, and get the socket descriptor.
827 : */
828 : static void
829 : read_inheritable_socket(SOCKET *dest, InheritableSocket *src)
830 : {
831 : SOCKET s;
832 :
833 : if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0)
834 : {
835 : /* Not a real socket! */
836 : *dest = src->origsocket;
837 : }
838 : else
839 : {
840 : /* Actual socket, so create from structure */
841 : s = WSASocket(FROM_PROTOCOL_INFO,
842 : FROM_PROTOCOL_INFO,
843 : FROM_PROTOCOL_INFO,
844 : &src->wsainfo,
845 : 0,
846 : 0);
847 : if (s == INVALID_SOCKET)
848 : {
849 : write_stderr("could not create inherited socket: error code %d\n",
850 : WSAGetLastError());
851 : exit(1);
852 : }
853 : *dest = s;
854 :
855 : /*
856 : * To make sure we don't get two references to the same socket, close
857 : * the original one. (This would happen when inheritance actually
858 : * works..
859 : */
860 : closesocket(src->origsocket);
861 : }
862 : }
863 : #endif
864 :
865 : static void
866 : read_backend_variables(char *id, char **startup_data, size_t *startup_data_len)
867 : {
868 : BackendParameters param;
869 :
870 : #ifndef WIN32
871 : /* Non-win32 implementation reads from file */
872 : FILE *fp;
873 :
874 : /* Open file */
875 : fp = AllocateFile(id, PG_BINARY_R);
876 : if (!fp)
877 : {
878 : write_stderr("could not open backend variables file \"%s\": %m\n", id);
879 : exit(1);
880 : }
881 :
882 : if (fread(¶m, sizeof(param), 1, fp) != 1)
883 : {
884 : write_stderr("could not read from backend variables file \"%s\": %m\n", id);
885 : exit(1);
886 : }
887 :
888 : /* read startup data */
889 : *startup_data_len = param.startup_data_len;
890 : if (param.startup_data_len > 0)
891 : {
892 : *startup_data = palloc(*startup_data_len);
893 : if (fread(*startup_data, *startup_data_len, 1, fp) != 1)
894 : {
895 : write_stderr("could not read startup data from backend variables file \"%s\": %m\n",
896 : id);
897 : exit(1);
898 : }
899 : }
900 : else
901 : *startup_data = NULL;
902 :
903 : /* Release file */
904 : FreeFile(fp);
905 : if (unlink(id) != 0)
906 : {
907 : write_stderr("could not remove file \"%s\": %m\n", id);
908 : exit(1);
909 : }
910 : #else
911 : /* Win32 version uses mapped file */
912 : HANDLE paramHandle;
913 : BackendParameters *paramp;
914 :
915 : #ifdef _WIN64
916 : paramHandle = (HANDLE) _atoi64(id);
917 : #else
918 : paramHandle = (HANDLE) atol(id);
919 : #endif
920 : paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0);
921 : if (!paramp)
922 : {
923 : write_stderr("could not map view of backend variables: error code %lu\n",
924 : GetLastError());
925 : exit(1);
926 : }
927 :
928 : memcpy(¶m, paramp, sizeof(BackendParameters));
929 :
930 : /* read startup data */
931 : *startup_data_len = param.startup_data_len;
932 : if (param.startup_data_len > 0)
933 : {
934 : *startup_data = palloc(paramp->startup_data_len);
935 : memcpy(*startup_data, paramp->startup_data, param.startup_data_len);
936 : }
937 : else
938 : *startup_data = NULL;
939 :
940 : if (!UnmapViewOfFile(paramp))
941 : {
942 : write_stderr("could not unmap view of backend variables: error code %lu\n",
943 : GetLastError());
944 : exit(1);
945 : }
946 :
947 : if (!CloseHandle(paramHandle))
948 : {
949 : write_stderr("could not close handle to backend parameter variables: error code %lu\n",
950 : GetLastError());
951 : exit(1);
952 : }
953 : #endif
954 :
955 : restore_backend_variables(¶m);
956 : }
957 :
958 : /* Restore critical backend variables from the BackendParameters struct */
959 : static void
960 : restore_backend_variables(BackendParameters *param)
961 : {
962 : if (param->client_sock.sock != PGINVALID_SOCKET)
963 : {
964 : MyClientSocket = MemoryContextAlloc(TopMemoryContext, sizeof(ClientSocket));
965 : memcpy(MyClientSocket, ¶m->client_sock, sizeof(ClientSocket));
966 : read_inheritable_socket(&MyClientSocket->sock, ¶m->inh_sock);
967 : }
968 :
969 : SetDataDir(param->DataDir);
970 :
971 : MyCancelKey = param->MyCancelKey;
972 : MyPMChildSlot = param->MyPMChildSlot;
973 :
974 : #ifdef WIN32
975 : ShmemProtectiveRegion = param->ShmemProtectiveRegion;
976 : #endif
977 : UsedShmemSegID = param->UsedShmemSegID;
978 : UsedShmemSegAddr = param->UsedShmemSegAddr;
979 :
980 : ShmemLock = param->ShmemLock;
981 : ShmemBackendArray = param->ShmemBackendArray;
982 :
983 : #ifndef HAVE_SPINLOCKS
984 : SpinlockSemaArray = param->SpinlockSemaArray;
985 : #endif
986 : NamedLWLockTrancheRequests = param->NamedLWLockTrancheRequests;
987 : NamedLWLockTrancheArray = param->NamedLWLockTrancheArray;
988 : MainLWLockArray = param->MainLWLockArray;
989 : ProcStructLock = param->ProcStructLock;
990 : ProcGlobal = param->ProcGlobal;
991 : AuxiliaryProcs = param->AuxiliaryProcs;
992 : PreparedXactProcs = param->PreparedXactProcs;
993 : PMSignalState = param->PMSignalState;
994 :
995 : PostmasterPid = param->PostmasterPid;
996 : PgStartTime = param->PgStartTime;
997 : PgReloadTime = param->PgReloadTime;
998 : first_syslogger_file_time = param->first_syslogger_file_time;
999 :
1000 : redirection_done = param->redirection_done;
1001 : IsBinaryUpgrade = param->IsBinaryUpgrade;
1002 : query_id_enabled = param->query_id_enabled;
1003 : max_safe_fds = param->max_safe_fds;
1004 :
1005 : MaxBackends = param->MaxBackends;
1006 :
1007 : #ifdef WIN32
1008 : PostmasterHandle = param->PostmasterHandle;
1009 : pgwin32_initial_signal_pipe = param->initial_signal_pipe;
1010 : #else
1011 : memcpy(&postmaster_alive_fds, ¶m->postmaster_alive_fds,
1012 : sizeof(postmaster_alive_fds));
1013 : #endif
1014 :
1015 : memcpy(&syslogPipe, ¶m->syslogPipe, sizeof(syslogPipe));
1016 :
1017 : strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH);
1018 :
1019 : strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH);
1020 :
1021 : /*
1022 : * We need to restore fd.c's counts of externally-opened FDs; to avoid
1023 : * confusion, be sure to do this after restoring max_safe_fds. (Note:
1024 : * BackendInitialize will handle this for (*client_sock)->sock.)
1025 : */
1026 : #ifndef WIN32
1027 : if (postmaster_alive_fds[0] >= 0)
1028 : ReserveExternalFD();
1029 : if (postmaster_alive_fds[1] >= 0)
1030 : ReserveExternalFD();
1031 : #endif
1032 : }
1033 :
1034 : #endif /* EXEC_BACKEND */
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