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) 1996-2026, 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 "libpq/libpq-be.h"
37 : #include "miscadmin.h"
38 : #include "postmaster/autovacuum.h"
39 : #include "postmaster/bgworker_internals.h"
40 : #include "postmaster/bgwriter.h"
41 : #include "postmaster/fork_process.h"
42 : #include "postmaster/pgarch.h"
43 : #include "postmaster/postmaster.h"
44 : #include "postmaster/startup.h"
45 : #include "postmaster/syslogger.h"
46 : #include "postmaster/walsummarizer.h"
47 : #include "postmaster/walwriter.h"
48 : #include "replication/slotsync.h"
49 : #include "replication/walreceiver.h"
50 : #include "storage/dsm.h"
51 : #include "storage/io_worker.h"
52 : #include "storage/ipc.h"
53 : #include "storage/pg_shmem.h"
54 : #include "storage/shmem_internal.h"
55 : #include "tcop/backend_startup.h"
56 : #include "utils/memutils.h"
57 :
58 : #ifdef EXEC_BACKEND
59 : #include "nodes/queryjumble.h"
60 : #include "portability/instr_time.h"
61 : #include "storage/pg_shmem.h"
62 : #include "storage/spin.h"
63 : #endif
64 :
65 :
66 : #ifdef EXEC_BACKEND
67 :
68 : #include "common/file_utils.h"
69 : #include "storage/fd.h"
70 : #include "storage/lwlock.h"
71 : #include "storage/pmsignal.h"
72 : #include "storage/proc.h"
73 : #include "storage/procsignal.h"
74 : #include "tcop/tcopprot.h"
75 : #include "utils/injection_point.h"
76 :
77 : /* Type for a socket that can be inherited to a client process */
78 : #ifdef WIN32
79 : typedef struct
80 : {
81 : SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET
82 : * if not a socket */
83 : WSAPROTOCOL_INFO wsainfo;
84 : } InheritableSocket;
85 : #else
86 : typedef int InheritableSocket;
87 : #endif
88 :
89 : /*
90 : * Structure contains all variables passed to exec:ed backends
91 : */
92 : typedef struct
93 : {
94 : char DataDir[MAXPGPATH];
95 : #ifndef WIN32
96 : unsigned long UsedShmemSegID;
97 : #else
98 : void *ShmemProtectiveRegion;
99 : HANDLE UsedShmemSegID;
100 : #endif
101 : void *UsedShmemSegAddr;
102 : #ifdef USE_INJECTION_POINTS
103 : struct InjectionPointsCtl *ActiveInjectionPoints;
104 : #endif
105 : PROC_HDR *ProcGlobal;
106 : PGPROC *AuxiliaryProcs;
107 : PGPROC *PreparedXactProcs;
108 : volatile PMSignalData *PMSignalState;
109 : ProcSignalHeader *ProcSignal;
110 : pid_t PostmasterPid;
111 : TimestampTz PgStartTime;
112 : TimestampTz PgReloadTime;
113 : pg_time_t first_syslogger_file_time;
114 : bool redirection_done;
115 : bool IsBinaryUpgrade;
116 : bool query_id_enabled;
117 : int max_safe_fds;
118 : int MaxBackends;
119 : int num_pmchild_slots;
120 : #ifdef WIN32
121 : HANDLE PostmasterHandle;
122 : HANDLE initial_signal_pipe;
123 : HANDLE syslogPipe[2];
124 : #else
125 : int postmaster_alive_fds[2];
126 : int syslogPipe[2];
127 : #endif
128 : char my_exec_path[MAXPGPATH];
129 : char pkglib_path[MAXPGPATH];
130 :
131 : int MyPMChildSlot;
132 :
133 : int32 timing_tsc_frequency_khz;
134 :
135 : /*
136 : * These are only used by backend processes, but are here because passing
137 : * a socket needs some special handling on Windows. 'client_sock' is an
138 : * explicit argument to postmaster_child_launch, but is stored in
139 : * MyClientSocket in the child process.
140 : */
141 : ClientSocket client_sock;
142 : InheritableSocket inh_sock;
143 :
144 : /*
145 : * Extra startup data, content depends on the child process.
146 : */
147 : size_t startup_data_len;
148 : char startup_data[FLEXIBLE_ARRAY_MEMBER];
149 : } BackendParameters;
150 :
151 : #define SizeOfBackendParameters(startup_data_len) (offsetof(BackendParameters, startup_data) + startup_data_len)
152 :
153 : static void read_backend_variables(char *id, void **startup_data, size_t *startup_data_len);
154 : static void restore_backend_variables(BackendParameters *param);
155 :
156 : static bool save_backend_variables(BackendParameters *param, int child_slot,
157 : const ClientSocket *client_sock,
158 : #ifdef WIN32
159 : HANDLE childProcess, pid_t childPid,
160 : #endif
161 : const void *startup_data, size_t startup_data_len);
162 :
163 : static pid_t internal_forkexec(BackendType child_kind, int child_slot,
164 : const void *startup_data, size_t startup_data_len,
165 : const 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) (const void *startup_data, size_t startup_data_len);
176 : bool shmem_attach;
177 : } child_process_kind;
178 :
179 : static child_process_kind child_process_kinds[] = {
180 : #define PG_PROCTYPE(bktype, bkcategory, description, main_func, shmem_attach) \
181 : [bktype] = {description, main_func, shmem_attach},
182 : #include "postmaster/proctypelist.h"
183 : #undef PG_PROCTYPE
184 : };
185 :
186 : const char *
187 1123 : PostmasterChildName(BackendType child_type)
188 : {
189 1123 : return child_process_kinds[child_type].name;
190 : }
191 :
192 : /*
193 : * Start a new postmaster child process.
194 : *
195 : * The child process will be restored to roughly the same state whether
196 : * EXEC_BACKEND is used or not: it will be attached to shared memory if
197 : * appropriate, and fds and other resources that we've inherited from
198 : * postmaster that are not needed in a child process have been closed.
199 : *
200 : * 'child_slot' is the PMChildFlags array index reserved for the child
201 : * process. 'startup_data' is an optional contiguous chunk of data that is
202 : * passed to the child process.
203 : */
204 : pid_t
205 27007 : postmaster_child_launch(BackendType child_type, int child_slot,
206 : void *startup_data, size_t startup_data_len,
207 : const ClientSocket *client_sock)
208 : {
209 : pid_t pid;
210 :
211 : Assert(IsPostmasterEnvironment && !IsUnderPostmaster);
212 :
213 : /* Capture time Postmaster initiates process creation for logging */
214 27007 : if (IsExternalConnectionBackend(child_type))
215 14851 : ((BackendStartupData *) startup_data)->fork_started = GetCurrentTimestamp();
216 :
217 : #ifdef EXEC_BACKEND
218 : pid = internal_forkexec(child_type, child_slot,
219 : startup_data, startup_data_len, client_sock);
220 : /* the child process will arrive in SubPostmasterMain */
221 : #else /* !EXEC_BACKEND */
222 27007 : pid = fork_process();
223 51391 : if (pid == 0) /* child */
224 : {
225 24384 : MyBackendType = child_type;
226 :
227 : /* Capture and transfer timings that may be needed for logging */
228 24384 : if (IsExternalConnectionBackend(child_type))
229 : {
230 14675 : conn_timing.socket_create =
231 14675 : ((BackendStartupData *) startup_data)->socket_created;
232 14675 : conn_timing.fork_start =
233 14675 : ((BackendStartupData *) startup_data)->fork_started;
234 14675 : conn_timing.fork_end = GetCurrentTimestamp();
235 : }
236 :
237 : /* Close the postmaster's sockets */
238 24384 : ClosePostmasterPorts(child_type == B_LOGGER);
239 :
240 : /* Detangle from postmaster */
241 24384 : InitPostmasterChild();
242 :
243 : /* Detach shared memory if not needed. */
244 24384 : if (!child_process_kinds[child_type].shmem_attach)
245 : {
246 1 : dsm_detach_all();
247 1 : PGSharedMemoryDetach();
248 : }
249 :
250 : /*
251 : * Enter the Main function with TopMemoryContext. The startup data is
252 : * allocated in PostmasterContext, so we cannot release it here yet.
253 : * The Main function will do it after it's done handling the startup
254 : * data.
255 : */
256 24384 : MemoryContextSwitchTo(TopMemoryContext);
257 :
258 24384 : MyPMChildSlot = child_slot;
259 24384 : if (client_sock)
260 : {
261 14882 : MyClientSocket = palloc_object(ClientSocket);
262 14882 : memcpy(MyClientSocket, client_sock, sizeof(ClientSocket));
263 : }
264 :
265 : /*
266 : * Run the appropriate Main function
267 : */
268 24384 : child_process_kinds[child_type].main_fn(startup_data, startup_data_len);
269 0 : pg_unreachable(); /* main_fn never returns */
270 : }
271 : #endif /* EXEC_BACKEND */
272 27007 : return pid;
273 : }
274 :
275 : #ifdef EXEC_BACKEND
276 : #ifndef WIN32
277 :
278 : /*
279 : * internal_forkexec non-win32 implementation
280 : *
281 : * - writes out backend variables to the parameter file
282 : * - fork():s, and then exec():s the child process
283 : */
284 : static pid_t
285 : internal_forkexec(BackendType child_kind, int child_slot,
286 : const void *startup_data, size_t startup_data_len, const ClientSocket *client_sock)
287 : {
288 : static unsigned long tmpBackendFileNum = 0;
289 : pid_t pid;
290 : char tmpfilename[MAXPGPATH];
291 : size_t paramsz;
292 : BackendParameters *param;
293 : FILE *fp;
294 : char *argv[4];
295 : char forkav[MAXPGPATH];
296 :
297 : /*
298 : * Use palloc0 to make sure padding bytes are initialized, to prevent
299 : * Valgrind from complaining about writing uninitialized bytes to the
300 : * file. This isn't performance critical, and the win32 implementation
301 : * initializes the padding bytes to zeros, so do it even when not using
302 : * Valgrind.
303 : */
304 : paramsz = SizeOfBackendParameters(startup_data_len);
305 : param = palloc0(paramsz);
306 : if (!save_backend_variables(param, child_slot, client_sock, startup_data, startup_data_len))
307 : {
308 : pfree(param);
309 : return -1; /* log made by save_backend_variables */
310 : }
311 :
312 : /* Calculate name for temp file */
313 : snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu",
314 : PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX,
315 : MyProcPid, ++tmpBackendFileNum);
316 :
317 : /* Open file */
318 : fp = AllocateFile(tmpfilename, PG_BINARY_W);
319 : if (!fp)
320 : {
321 : /*
322 : * As in OpenTemporaryFileInTablespace, try to make the temp-file
323 : * directory, ignoring errors.
324 : */
325 : (void) MakePGDirectory(PG_TEMP_FILES_DIR);
326 :
327 : fp = AllocateFile(tmpfilename, PG_BINARY_W);
328 : if (!fp)
329 : {
330 : ereport(LOG,
331 : (errcode_for_file_access(),
332 : errmsg("could not create file \"%s\": %m",
333 : tmpfilename)));
334 : pfree(param);
335 : return -1;
336 : }
337 : }
338 :
339 : if (fwrite(param, paramsz, 1, fp) != 1)
340 : {
341 : ereport(LOG,
342 : (errcode_for_file_access(),
343 : errmsg("could not write to file \"%s\": %m", tmpfilename)));
344 : FreeFile(fp);
345 : pfree(param);
346 : return -1;
347 : }
348 : pfree(param);
349 :
350 : /* Release file */
351 : if (FreeFile(fp))
352 : {
353 : ereport(LOG,
354 : (errcode_for_file_access(),
355 : errmsg("could not write to file \"%s\": %m", tmpfilename)));
356 : return -1;
357 : }
358 :
359 : /* set up argv properly */
360 : argv[0] = "postgres";
361 : snprintf(forkav, MAXPGPATH, "--forkchild=%d", (int) child_kind);
362 : argv[1] = forkav;
363 : /* Insert temp file name after --forkchild argument */
364 : argv[2] = tmpfilename;
365 : argv[3] = NULL;
366 :
367 : /* Fire off execv in child */
368 : if ((pid = fork_process()) == 0)
369 : {
370 : if (execv(postgres_exec_path, argv) < 0)
371 : {
372 : ereport(LOG,
373 : (errmsg("could not execute server process \"%s\": %m",
374 : postgres_exec_path)));
375 : /* We're already in the child process here, can't return */
376 : exit(1);
377 : }
378 : }
379 :
380 : return pid; /* Parent returns pid, or -1 on fork failure */
381 : }
382 : #else /* WIN32 */
383 :
384 : /*
385 : * internal_forkexec win32 implementation
386 : *
387 : * - starts backend using CreateProcess(), in suspended state
388 : * - writes out backend variables to the parameter file
389 : * - during this, duplicates handles and sockets required for
390 : * inheritance into the new process
391 : * - resumes execution of the new process once the backend parameter
392 : * file is complete.
393 : */
394 : static pid_t
395 : internal_forkexec(BackendType child_kind, int child_slot,
396 : const void *startup_data, size_t startup_data_len, const ClientSocket *client_sock)
397 : {
398 : int retry_count = 0;
399 : STARTUPINFO si;
400 : PROCESS_INFORMATION pi;
401 : char cmdLine[MAXPGPATH * 2];
402 : HANDLE paramHandle;
403 : BackendParameters *param;
404 : SECURITY_ATTRIBUTES sa;
405 : size_t paramsz;
406 : char paramHandleStr[32];
407 : int l;
408 :
409 : paramsz = SizeOfBackendParameters(startup_data_len);
410 :
411 : /* Resume here if we need to retry */
412 : retry:
413 :
414 : /* Set up shared memory for parameter passing */
415 : ZeroMemory(&sa, sizeof(sa));
416 : sa.nLength = sizeof(sa);
417 : sa.bInheritHandle = TRUE;
418 : paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE,
419 : &sa,
420 : PAGE_READWRITE,
421 : 0,
422 : paramsz,
423 : NULL);
424 : if (paramHandle == INVALID_HANDLE_VALUE)
425 : {
426 : ereport(LOG,
427 : (errmsg("could not create backend parameter file mapping: error code %lu",
428 : GetLastError())));
429 : return -1;
430 : }
431 : param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, paramsz);
432 : if (!param)
433 : {
434 : ereport(LOG,
435 : (errmsg("could not map backend parameter memory: error code %lu",
436 : GetLastError())));
437 : CloseHandle(paramHandle);
438 : return -1;
439 : }
440 :
441 : /* Format the cmd line */
442 : #ifdef _WIN64
443 : sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle);
444 : #else
445 : sprintf(paramHandleStr, "%lu", (DWORD) paramHandle);
446 : #endif
447 : l = snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\" --forkchild=%d %s",
448 : postgres_exec_path, (int) child_kind, paramHandleStr);
449 : if (l >= sizeof(cmdLine))
450 : {
451 : ereport(LOG,
452 : (errmsg("subprocess command line too long")));
453 : UnmapViewOfFile(param);
454 : CloseHandle(paramHandle);
455 : return -1;
456 : }
457 :
458 : memset(&pi, 0, sizeof(pi));
459 : memset(&si, 0, sizeof(si));
460 : si.cb = sizeof(si);
461 :
462 : /*
463 : * Create the subprocess in a suspended state. This will be resumed later,
464 : * once we have written out the parameter file.
465 : */
466 : if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED,
467 : NULL, NULL, &si, &pi))
468 : {
469 : ereport(LOG,
470 : (errmsg("CreateProcess() call failed: %m (error code %lu)",
471 : GetLastError())));
472 : UnmapViewOfFile(param);
473 : CloseHandle(paramHandle);
474 : return -1;
475 : }
476 :
477 : if (!save_backend_variables(param, child_slot, client_sock,
478 : pi.hProcess, pi.dwProcessId,
479 : startup_data, startup_data_len))
480 : {
481 : /*
482 : * log made by save_backend_variables, but we have to clean up the
483 : * mess with the half-started process
484 : */
485 : if (!TerminateProcess(pi.hProcess, 255))
486 : ereport(LOG,
487 : (errmsg_internal("could not terminate unstarted process: error code %lu",
488 : GetLastError())));
489 : CloseHandle(pi.hProcess);
490 : CloseHandle(pi.hThread);
491 : UnmapViewOfFile(param);
492 : CloseHandle(paramHandle);
493 : return -1; /* log made by save_backend_variables */
494 : }
495 :
496 : /* Drop the parameter shared memory that is now inherited to the backend */
497 : if (!UnmapViewOfFile(param))
498 : ereport(LOG,
499 : (errmsg("could not unmap view of backend parameter file: error code %lu",
500 : GetLastError())));
501 : if (!CloseHandle(paramHandle))
502 : ereport(LOG,
503 : (errmsg("could not close handle to backend parameter file: error code %lu",
504 : GetLastError())));
505 :
506 : /*
507 : * Reserve the memory region used by our main shared memory segment before
508 : * we resume the child process. Normally this should succeed, but if ASLR
509 : * is active then it might sometimes fail due to the stack or heap having
510 : * gotten mapped into that range. In that case, just terminate the
511 : * process and retry.
512 : */
513 : if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess))
514 : {
515 : /* pgwin32_ReserveSharedMemoryRegion already made a log entry */
516 : if (!TerminateProcess(pi.hProcess, 255))
517 : ereport(LOG,
518 : (errmsg_internal("could not terminate process that failed to reserve memory: error code %lu",
519 : GetLastError())));
520 : CloseHandle(pi.hProcess);
521 : CloseHandle(pi.hThread);
522 : if (++retry_count < 100)
523 : goto retry;
524 : ereport(LOG,
525 : (errmsg("giving up after too many tries to reserve shared memory"),
526 : errhint("This might be caused by ASLR or antivirus software.")));
527 : return -1;
528 : }
529 :
530 : /*
531 : * Now that the backend variables are written out, we start the child
532 : * thread so it can start initializing while we set up the rest of the
533 : * parent state.
534 : */
535 : if (ResumeThread(pi.hThread) == -1)
536 : {
537 : if (!TerminateProcess(pi.hProcess, 255))
538 : {
539 : ereport(LOG,
540 : (errmsg_internal("could not terminate unstartable process: error code %lu",
541 : GetLastError())));
542 : CloseHandle(pi.hProcess);
543 : CloseHandle(pi.hThread);
544 : return -1;
545 : }
546 : CloseHandle(pi.hProcess);
547 : CloseHandle(pi.hThread);
548 : ereport(LOG,
549 : (errmsg_internal("could not resume thread of unstarted process: error code %lu",
550 : GetLastError())));
551 : return -1;
552 : }
553 :
554 : /* Set up notification when the child process dies */
555 : pgwin32_register_deadchild_callback(pi.hProcess, pi.dwProcessId);
556 :
557 : /* Don't close pi.hProcess, it's owned by the deadchild callback now */
558 :
559 : CloseHandle(pi.hThread);
560 :
561 : return pi.dwProcessId;
562 : }
563 : #endif /* WIN32 */
564 :
565 : /*
566 : * SubPostmasterMain -- Get the fork/exec'd process into a state equivalent
567 : * to what it would be if we'd simply forked on Unix, and then
568 : * dispatch to the appropriate place.
569 : *
570 : * The first two command line arguments are expected to be "--forkchild=<kind>",
571 : * where <kind> indicates which process type we are to become, and
572 : * the name of a variables file that we can read to load data that would
573 : * have been inherited by fork() on Unix.
574 : */
575 : void
576 : SubPostmasterMain(int argc, char *argv[])
577 : {
578 : void *startup_data;
579 : size_t startup_data_len;
580 : char *child_kind;
581 : BackendType child_type;
582 : TimestampTz fork_end;
583 :
584 : /* In EXEC_BACKEND case we will not have inherited these settings */
585 : IsPostmasterEnvironment = true;
586 : whereToSendOutput = DestNone;
587 :
588 : /*
589 : * Capture the end of process creation for logging. We don't include the
590 : * time spent copying data from shared memory and setting up the backend.
591 : */
592 : fork_end = GetCurrentTimestamp();
593 :
594 : /* Setup essential subsystems (to ensure elog() behaves sanely) */
595 : InitializeGUCOptions();
596 :
597 : /* Check we got appropriate args */
598 : if (argc != 3)
599 : elog(FATAL, "invalid subpostmaster invocation");
600 :
601 : /*
602 : * Parse the --forkchild argument to find our process type. We rely with
603 : * malice aforethought on atoi returning 0 (B_INVALID) on error.
604 : */
605 : if (strncmp(argv[1], "--forkchild=", 12) != 0)
606 : elog(FATAL, "invalid subpostmaster invocation (--forkchild argument missing)");
607 : child_kind = argv[1] + 12;
608 : child_type = (BackendType) atoi(child_kind);
609 : if (child_type <= B_INVALID || child_type > BACKEND_NUM_TYPES - 1)
610 : elog(ERROR, "unknown child kind %s", child_kind);
611 : MyBackendType = child_type;
612 :
613 : /* Read in the variables file */
614 : read_backend_variables(argv[2], &startup_data, &startup_data_len);
615 :
616 : /* Close the postmaster's sockets (as soon as we know them) */
617 : ClosePostmasterPorts(child_type == B_LOGGER);
618 :
619 : /* Setup as postmaster child */
620 : InitPostmasterChild();
621 :
622 : /*
623 : * If appropriate, physically re-attach to shared memory segment. We want
624 : * to do this before going any further to ensure that we can attach at the
625 : * same address the postmaster used. On the other hand, if we choose not
626 : * to re-attach, we may have other cleanup to do.
627 : *
628 : * If testing EXEC_BACKEND on Linux, you should run this as root before
629 : * starting the postmaster:
630 : *
631 : * sysctl -w kernel.randomize_va_space=0
632 : *
633 : * This prevents using randomized stack and code addresses that cause the
634 : * child process's memory map to be different from the parent's, making it
635 : * sometimes impossible to attach to shared memory at the desired address.
636 : * Return the setting to its old value (usually '1' or '2') when finished.
637 : */
638 : if (child_process_kinds[child_type].shmem_attach)
639 : PGSharedMemoryReAttach();
640 : else
641 : PGSharedMemoryNoReAttach();
642 :
643 : /* Read in remaining GUC variables */
644 : read_nondefault_variables();
645 :
646 : /* Capture and transfer timings that may be needed for log_connections */
647 : if (IsExternalConnectionBackend(child_type))
648 : {
649 : conn_timing.socket_create =
650 : ((BackendStartupData *) startup_data)->socket_created;
651 : conn_timing.fork_start =
652 : ((BackendStartupData *) startup_data)->fork_started;
653 : conn_timing.fork_end = fork_end;
654 : }
655 :
656 : /*
657 : * Check that the data directory looks valid, which will also check the
658 : * privileges on the data directory and update our umask and file/group
659 : * variables for creating files later. Note: this should really be done
660 : * before we create any files or directories.
661 : */
662 : checkDataDir();
663 :
664 : /*
665 : * (re-)read control file, as it contains config. The postmaster will
666 : * already have read this, but this process doesn't know about that.
667 : */
668 : LocalProcessControlFile(false);
669 :
670 : RegisterBuiltinShmemCallbacks();
671 :
672 : /*
673 : * Reload any libraries that were preloaded by the postmaster. Since we
674 : * exec'd this process, those libraries didn't come along with us; but we
675 : * should load them into all child processes to be consistent with the
676 : * non-EXEC_BACKEND behavior.
677 : */
678 : process_shared_preload_libraries();
679 :
680 : /* Restore basic shared memory pointers */
681 : if (UsedShmemSegAddr != NULL)
682 : {
683 : InitShmemAllocator(UsedShmemSegAddr);
684 : ShmemCallRequestCallbacks();
685 : }
686 :
687 : /*
688 : * Run the appropriate Main function
689 : */
690 : child_process_kinds[child_type].main_fn(startup_data, startup_data_len);
691 : pg_unreachable(); /* main_fn never returns */
692 : }
693 :
694 : #ifndef WIN32
695 : #define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true)
696 : #define read_inheritable_socket(dest, src) (*(dest) = *(src))
697 : #else
698 : static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child);
699 : static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src,
700 : pid_t childPid);
701 : static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src);
702 : #endif
703 :
704 :
705 : /* Save critical backend variables into the BackendParameters struct */
706 : static bool
707 : save_backend_variables(BackendParameters *param,
708 : int child_slot, const ClientSocket *client_sock,
709 : #ifdef WIN32
710 : HANDLE childProcess, pid_t childPid,
711 : #endif
712 : const void *startup_data, size_t startup_data_len)
713 : {
714 : if (client_sock)
715 : memcpy(¶m->client_sock, client_sock, sizeof(ClientSocket));
716 : else
717 : memset(¶m->client_sock, 0, sizeof(ClientSocket));
718 : if (!write_inheritable_socket(¶m->inh_sock,
719 : client_sock ? client_sock->sock : PGINVALID_SOCKET,
720 : childPid))
721 : return false;
722 :
723 : strlcpy(param->DataDir, DataDir, MAXPGPATH);
724 :
725 : param->MyPMChildSlot = child_slot;
726 :
727 : #ifdef WIN32
728 : param->ShmemProtectiveRegion = ShmemProtectiveRegion;
729 : #endif
730 : param->UsedShmemSegID = UsedShmemSegID;
731 : param->UsedShmemSegAddr = UsedShmemSegAddr;
732 :
733 : #ifdef USE_INJECTION_POINTS
734 : param->ActiveInjectionPoints = ActiveInjectionPoints;
735 : #endif
736 :
737 : param->ProcGlobal = ProcGlobal;
738 : param->AuxiliaryProcs = AuxiliaryProcs;
739 : param->PreparedXactProcs = PreparedXactProcs;
740 : param->PMSignalState = PMSignalState;
741 : param->ProcSignal = ProcSignal;
742 :
743 : param->PostmasterPid = PostmasterPid;
744 : param->PgStartTime = PgStartTime;
745 : param->PgReloadTime = PgReloadTime;
746 : param->first_syslogger_file_time = first_syslogger_file_time;
747 :
748 : param->redirection_done = redirection_done;
749 : param->IsBinaryUpgrade = IsBinaryUpgrade;
750 : param->query_id_enabled = query_id_enabled;
751 : param->max_safe_fds = max_safe_fds;
752 :
753 : param->MaxBackends = MaxBackends;
754 : param->num_pmchild_slots = num_pmchild_slots;
755 :
756 : param->timing_tsc_frequency_khz = timing_tsc_frequency_khz;
757 :
758 : #ifdef WIN32
759 : param->PostmasterHandle = PostmasterHandle;
760 : if (!write_duplicated_handle(¶m->initial_signal_pipe,
761 : pgwin32_create_signal_listener(childPid),
762 : childProcess))
763 : return false;
764 : #else
765 : memcpy(¶m->postmaster_alive_fds, &postmaster_alive_fds,
766 : sizeof(postmaster_alive_fds));
767 : #endif
768 :
769 : memcpy(¶m->syslogPipe, &syslogPipe, sizeof(syslogPipe));
770 :
771 : strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH);
772 :
773 : strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH);
774 :
775 : param->startup_data_len = startup_data_len;
776 : if (startup_data_len > 0)
777 : memcpy(param->startup_data, startup_data, startup_data_len);
778 :
779 : return true;
780 : }
781 :
782 : #ifdef WIN32
783 : /*
784 : * Duplicate a handle for usage in a child process, and write the child
785 : * process instance of the handle to the parameter file.
786 : */
787 : static bool
788 : write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess)
789 : {
790 : HANDLE hChild = INVALID_HANDLE_VALUE;
791 :
792 : if (!DuplicateHandle(GetCurrentProcess(),
793 : src,
794 : childProcess,
795 : &hChild,
796 : 0,
797 : TRUE,
798 : DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
799 : {
800 : ereport(LOG,
801 : (errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu",
802 : GetLastError())));
803 : return false;
804 : }
805 :
806 : *dest = hChild;
807 : return true;
808 : }
809 :
810 : /*
811 : * Duplicate a socket for usage in a child process, and write the resulting
812 : * structure to the parameter file.
813 : * This is required because a number of LSPs (Layered Service Providers) very
814 : * common on Windows (antivirus, firewalls, download managers etc) break
815 : * straight socket inheritance.
816 : */
817 : static bool
818 : write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid)
819 : {
820 : dest->origsocket = src;
821 : if (src != 0 && src != PGINVALID_SOCKET)
822 : {
823 : /* Actual socket */
824 : if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0)
825 : {
826 : ereport(LOG,
827 : (errmsg("could not duplicate socket %d for use in backend: error code %d",
828 : (int) src, WSAGetLastError())));
829 : return false;
830 : }
831 : }
832 : return true;
833 : }
834 :
835 : /*
836 : * Read a duplicate socket structure back, and get the socket descriptor.
837 : */
838 : static void
839 : read_inheritable_socket(SOCKET *dest, InheritableSocket *src)
840 : {
841 : SOCKET s;
842 :
843 : if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0)
844 : {
845 : /* Not a real socket! */
846 : *dest = src->origsocket;
847 : }
848 : else
849 : {
850 : /* Actual socket, so create from structure */
851 : s = WSASocket(FROM_PROTOCOL_INFO,
852 : FROM_PROTOCOL_INFO,
853 : FROM_PROTOCOL_INFO,
854 : &src->wsainfo,
855 : 0,
856 : 0);
857 : if (s == INVALID_SOCKET)
858 : {
859 : write_stderr("could not create inherited socket: error code %d\n",
860 : WSAGetLastError());
861 : exit(1);
862 : }
863 : *dest = s;
864 :
865 : /*
866 : * To make sure we don't get two references to the same socket, close
867 : * the original one. (This would happen when inheritance actually
868 : * works..
869 : */
870 : closesocket(src->origsocket);
871 : }
872 : }
873 : #endif
874 :
875 : static void
876 : read_backend_variables(char *id, void **startup_data, size_t *startup_data_len)
877 : {
878 : BackendParameters param;
879 :
880 : #ifndef WIN32
881 : /* Non-win32 implementation reads from file */
882 : FILE *fp;
883 :
884 : /* Open file */
885 : fp = AllocateFile(id, PG_BINARY_R);
886 : if (!fp)
887 : {
888 : write_stderr("could not open backend variables file \"%s\": %m\n", id);
889 : exit(1);
890 : }
891 :
892 : if (fread(¶m, sizeof(param), 1, fp) != 1)
893 : {
894 : write_stderr("could not read from backend variables file \"%s\": %m\n", id);
895 : exit(1);
896 : }
897 :
898 : /* read startup data */
899 : *startup_data_len = param.startup_data_len;
900 : if (param.startup_data_len > 0)
901 : {
902 : *startup_data = palloc(*startup_data_len);
903 : if (fread(*startup_data, *startup_data_len, 1, fp) != 1)
904 : {
905 : write_stderr("could not read startup data from backend variables file \"%s\": %m\n",
906 : id);
907 : exit(1);
908 : }
909 : }
910 : else
911 : *startup_data = NULL;
912 :
913 : /* Release file */
914 : FreeFile(fp);
915 : if (unlink(id) != 0)
916 : {
917 : write_stderr("could not remove file \"%s\": %m\n", id);
918 : exit(1);
919 : }
920 : #else
921 : /* Win32 version uses mapped file */
922 : HANDLE paramHandle;
923 : BackendParameters *paramp;
924 :
925 : #ifdef _WIN64
926 : paramHandle = (HANDLE) _atoi64(id);
927 : #else
928 : paramHandle = (HANDLE) atol(id);
929 : #endif
930 : paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0);
931 : if (!paramp)
932 : {
933 : write_stderr("could not map view of backend variables: error code %lu\n",
934 : GetLastError());
935 : exit(1);
936 : }
937 :
938 : memcpy(¶m, paramp, sizeof(BackendParameters));
939 :
940 : /* read startup data */
941 : *startup_data_len = param.startup_data_len;
942 : if (param.startup_data_len > 0)
943 : {
944 : *startup_data = palloc(paramp->startup_data_len);
945 : memcpy(*startup_data, paramp->startup_data, param.startup_data_len);
946 : }
947 : else
948 : *startup_data = NULL;
949 :
950 : if (!UnmapViewOfFile(paramp))
951 : {
952 : write_stderr("could not unmap view of backend variables: error code %lu\n",
953 : GetLastError());
954 : exit(1);
955 : }
956 :
957 : if (!CloseHandle(paramHandle))
958 : {
959 : write_stderr("could not close handle to backend parameter variables: error code %lu\n",
960 : GetLastError());
961 : exit(1);
962 : }
963 : #endif
964 :
965 : restore_backend_variables(¶m);
966 : }
967 :
968 : /* Restore critical backend variables from the BackendParameters struct */
969 : static void
970 : restore_backend_variables(BackendParameters *param)
971 : {
972 : if (param->client_sock.sock != PGINVALID_SOCKET)
973 : {
974 : MyClientSocket = MemoryContextAlloc(TopMemoryContext, sizeof(ClientSocket));
975 : memcpy(MyClientSocket, ¶m->client_sock, sizeof(ClientSocket));
976 : read_inheritable_socket(&MyClientSocket->sock, ¶m->inh_sock);
977 : }
978 :
979 : SetDataDir(param->DataDir);
980 :
981 : MyPMChildSlot = param->MyPMChildSlot;
982 :
983 : #ifdef WIN32
984 : ShmemProtectiveRegion = param->ShmemProtectiveRegion;
985 : #endif
986 : UsedShmemSegID = param->UsedShmemSegID;
987 : UsedShmemSegAddr = param->UsedShmemSegAddr;
988 :
989 : #ifdef USE_INJECTION_POINTS
990 : ActiveInjectionPoints = param->ActiveInjectionPoints;
991 : #endif
992 :
993 : ProcGlobal = param->ProcGlobal;
994 : AuxiliaryProcs = param->AuxiliaryProcs;
995 : PreparedXactProcs = param->PreparedXactProcs;
996 : PMSignalState = param->PMSignalState;
997 : ProcSignal = param->ProcSignal;
998 :
999 : PostmasterPid = param->PostmasterPid;
1000 : PgStartTime = param->PgStartTime;
1001 : PgReloadTime = param->PgReloadTime;
1002 : first_syslogger_file_time = param->first_syslogger_file_time;
1003 :
1004 : redirection_done = param->redirection_done;
1005 : IsBinaryUpgrade = param->IsBinaryUpgrade;
1006 : query_id_enabled = param->query_id_enabled;
1007 : max_safe_fds = param->max_safe_fds;
1008 :
1009 : MaxBackends = param->MaxBackends;
1010 : num_pmchild_slots = param->num_pmchild_slots;
1011 :
1012 : timing_tsc_frequency_khz = param->timing_tsc_frequency_khz;
1013 :
1014 : /* Re-run logic usually done by assign_timing_clock_source */
1015 : pg_initialize_timing();
1016 : pg_set_timing_clock_source(timing_clock_source);
1017 :
1018 : #ifdef WIN32
1019 : PostmasterHandle = param->PostmasterHandle;
1020 : pgwin32_initial_signal_pipe = param->initial_signal_pipe;
1021 : #else
1022 : memcpy(&postmaster_alive_fds, ¶m->postmaster_alive_fds,
1023 : sizeof(postmaster_alive_fds));
1024 : #endif
1025 :
1026 : memcpy(&syslogPipe, ¶m->syslogPipe, sizeof(syslogPipe));
1027 :
1028 : strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH);
1029 :
1030 : strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH);
1031 :
1032 : /*
1033 : * We need to restore fd.c's counts of externally-opened FDs; to avoid
1034 : * confusion, be sure to do this after restoring max_safe_fds. (Note:
1035 : * BackendInitialize will handle this for (*client_sock)->sock.)
1036 : */
1037 : #ifndef WIN32
1038 : if (postmaster_alive_fds[0] >= 0)
1039 : ReserveExternalFD();
1040 : if (postmaster_alive_fds[1] >= 0)
1041 : ReserveExternalFD();
1042 : #endif
1043 : }
1044 :
1045 : #endif /* EXEC_BACKEND */
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