#include "postgres.h"
#include "libpq/pqsignal.h"

Include dependency graph for signal.c:

Functions
static DWORD WINAPI	pg_signal_thread (LPVOID param)

static BOOL WINAPI	pg_console_handler (DWORD dwCtrlType)

void	pg_usleep (long microsec)

void	pgwin32_signal_initialize (void)

void	pgwin32_dispatch_queued_signals (void)

int	pqsigsetmask (int mask)

pqsigfunc	pqsignal (int signum, pqsigfunc handler)

HANDLE	pgwin32_create_signal_listener (pid_t pid)

void	pg_queue_signal (int signum)

Variables
volatile int	pg_signal_queue

int	pg_signal_mask

HANDLE	pgwin32_signal_event

HANDLE	pgwin32_initial_signal_pipe = INVALID_HANDLE_VALUE

static CRITICAL_SECTION	pg_signal_crit_sec

static pqsigfunc	pg_signal_array [PG_SIGNAL_COUNT]

static pqsigfunc	pg_signal_defaults [PG_SIGNAL_COUNT]

Function Documentation

◆ pg_console_handler()

static BOOL WINAPI pg_console_handler ( DWORD dwCtrlType )

static

Definition at line 343 of file signal.c.

 {
     if (dwCtrlType == CTRL_C_EVENT ||
         dwCtrlType == CTRL_BREAK_EVENT ||
         dwCtrlType == CTRL_CLOSE_EVENT ||
         dwCtrlType == CTRL_SHUTDOWN_EVENT)
     {
         pg_queue_signal(SIGINT);
         return TRUE;
     }
     return FALSE;
 }

References pg_queue_signal().

Referenced by pgwin32_signal_initialize().

◆ pg_queue_signal()

void pg_queue_signal ( int signum )

Definition at line 225 of file signal.c.

 {
     Assert(pgwin32_signal_event != NULL);
     if (signum >= PG_SIGNAL_COUNT || signum <= 0)
         return;                 /* ignore any bad signal number */
  
     EnterCriticalSection(&pg_signal_crit_sec);
     pg_signal_queue |= sigmask(signum);
     LeaveCriticalSection(&pg_signal_crit_sec);
  
     SetEvent(pgwin32_signal_event);
 }

References Assert(), PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_queue, pgwin32_signal_event, and sigmask.

Referenced by pg_console_handler(), pg_signal_thread(), and pg_timer_thread().

◆ pg_signal_thread()

static DWORD WINAPI pg_signal_thread ( LPVOID param )

static

Definition at line 240 of file signal.c.

 {
     char        pipename[128];
     HANDLE      pipe = pgwin32_initial_signal_pipe;
  
     /* Set up pipe name, in case we have to re-create the pipe. */
     snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%lu", GetCurrentProcessId());
  
     for (;;)
     {
         BOOL        fConnected;
  
         /* Create a new pipe instance if we don't have one. */
         if (pipe == INVALID_HANDLE_VALUE)
         {
             pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
                                    PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
                                    PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);
  
             if (pipe == INVALID_HANDLE_VALUE)
             {
                 write_stderr("could not create signal listener pipe: error code %lu; retrying\n", GetLastError());
                 SleepEx(500, FALSE);
                 continue;
             }
         }
  
         /*
          * Wait for a client to connect.  If something connects before we
          * reach here, we'll get back a "failure" with ERROR_PIPE_CONNECTED,
          * which is actually a success (way to go, Microsoft).
          */
         fConnected = ConnectNamedPipe(pipe, NULL) ? TRUE : (GetLastError() == ERROR_PIPE_CONNECTED);
         if (fConnected)
         {
             /*
              * We have a connection from a would-be signal sender. Process it.
              */
             BYTE        sigNum;
             DWORD       bytes;
  
             if (ReadFile(pipe, &sigNum, 1, &bytes, NULL) &&
                 bytes == 1)
             {
                 /*
                  * Queue the signal before responding to the client.  In this
                  * way, it's guaranteed that once kill() has returned in the
                  * signal sender, the next CHECK_FOR_INTERRUPTS() in the
                  * signal recipient will see the signal.  (This is a stronger
                  * guarantee than POSIX makes; maybe we don't need it?  But
                  * without it, we've seen timing bugs on Windows that do not
                  * manifest on any known Unix.)
                  */
                 pg_queue_signal(sigNum);
  
                 /*
                  * Write something back to the client, allowing its
                  * CallNamedPipe() call to terminate.
                  */
                 WriteFile(pipe, &sigNum, 1, &bytes, NULL);  /* Don't care if it
                                                              * works or not */
  
                 /*
                  * We must wait for the client to read the data before we can
                  * disconnect, else the data will be lost.  (If the WriteFile
                  * call failed, there'll be nothing in the buffer, so this
                  * shouldn't block.)
                  */
                 FlushFileBuffers(pipe);
             }
             else
             {
                 /*
                  * If we fail to read a byte from the client, assume it's the
                  * client's problem and do nothing.  Perhaps it'd be better to
                  * force a pipe close and reopen?
                  */
             }
  
             /* Disconnect from client so that we can re-use the pipe. */
             DisconnectNamedPipe(pipe);
         }
         else
         {
             /*
              * Connection failed.  Cleanup and try again.
              *
              * This should never happen.  If it does, there's a window where
              * we'll miss signals until we manage to re-create the pipe.
              * However, just trying to use the same pipe again is probably not
              * going to work, so we have little choice.
              */
             CloseHandle(pipe);
             pipe = INVALID_HANDLE_VALUE;
         }
     }
     return 0;
 }

References pg_queue_signal(), pgwin32_initial_signal_pipe, snprintf, and write_stderr.

Referenced by pgwin32_signal_initialize().

◆ pg_usleep()

void pg_usleep ( long microsec )

Definition at line 53 of file signal.c.

 {
     if (unlikely(pgwin32_signal_event == NULL))
     {
         /*
          * If we're reached by pgwin32_open_handle() early in startup before
          * the signal event is set up, just fall back to a regular
          * non-interruptible sleep.
          */
         SleepEx((microsec < 500 ? 1 : (microsec + 500) / 1000), FALSE);
         return;
     }
  
     if (WaitForSingleObject(pgwin32_signal_event,
                             (microsec < 500 ? 1 : (microsec + 500) / 1000))
         == WAIT_OBJECT_0)
     {
         pgwin32_dispatch_queued_signals();
         errno = EINTR;
         return;
     }
 }

References EINTR, pgwin32_dispatch_queued_signals(), pgwin32_signal_event, and unlikely.

Referenced by _bt_pendingfsm_finalize(), auth_delay_checks(), AutoVacLauncherMain(), AutoVacWorkerMain(), BackendInitialize(), BackgroundWriterMain(), CheckpointerMain(), ConditionalXactLockTableWait(), CountOtherDBBackends(), CreateCheckPoint(), do_watch(), exec_prog(), FileRead(), FileWrite(), GetMultiXactIdMembers(), InitPostgres(), main(), perform_spin_delay(), pgarch_ArchiverCopyLoop(), pgwin32_recv(), read_local_xlog_page_guts(), regression_main(), RequestCheckpoint(), ResolveRecoveryConflictWithDatabase(), ResolveRecoveryConflictWithVirtualXIDs(), ServerLoop(), StartBackgroundWorker(), StartupXLOG(), StreamConnection(), threadRun(), wait_for_postmaster_promote(), wait_for_postmaster_start(), wait_for_postmaster_stop(), wait_pid(), WaitExceedsMaxStandbyDelay(), WALDumpOpenSegment(), WalSndWaitStopping(), WalWriterMain(), XactLockTableWait(), and XLogFlush().

◆ pgwin32_create_signal_listener()

HANDLE pgwin32_create_signal_listener ( pid_t pid )

Definition at line 193 of file signal.c.

 {
     char        pipename[128];
     HANDLE      pipe;
  
     snprintf(pipename, sizeof(pipename), "\\\\.\\pipe\\pgsignal_%u", (int) pid);
  
     pipe = CreateNamedPipe(pipename, PIPE_ACCESS_DUPLEX,
                            PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT,
                            PIPE_UNLIMITED_INSTANCES, 16, 16, 1000, NULL);
  
     if (pipe == INVALID_HANDLE_VALUE)
         ereport(ERROR,
                 (errmsg("could not create signal listener pipe for PID %d: error code %lu",
                         (int) pid, GetLastError())));
  
     return pipe;
 }

References ereport, errmsg(), ERROR, and snprintf.

◆ pgwin32_dispatch_queued_signals()

void pgwin32_dispatch_queued_signals ( void )

Definition at line 118 of file signal.c.

 {
     int         exec_mask;
  
     Assert(pgwin32_signal_event != NULL);
     EnterCriticalSection(&pg_signal_crit_sec);
     while ((exec_mask = UNBLOCKED_SIGNAL_QUEUE()) != 0)
     {
         /* One or more unblocked signals queued for execution */
         int         i;
  
         for (i = 1; i < PG_SIGNAL_COUNT; i++)
         {
             if (exec_mask & sigmask(i))
             {
                 /* Execute this signal */
                 pqsigfunc   sig = pg_signal_array[i];
  
                 if (sig == SIG_DFL)
                     sig = pg_signal_defaults[i];
                 pg_signal_queue &= ~sigmask(i);
                 if (sig != SIG_ERR && sig != SIG_IGN && sig != SIG_DFL)
                 {
                     LeaveCriticalSection(&pg_signal_crit_sec);
                     sig(i);
                     EnterCriticalSection(&pg_signal_crit_sec);
                     break;      /* Restart outer loop, in case signal mask or
                                  * queue has been modified inside signal
                                  * handler */
                 }
             }
         }
     }
     ResetEvent(pgwin32_signal_event);
     LeaveCriticalSection(&pg_signal_crit_sec);
 }

References Assert(), i, pg_signal_array, PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_defaults, pg_signal_queue, pgwin32_signal_event, sig, SIG_DFL, SIG_ERR, SIG_IGN, sigmask, and UNBLOCKED_SIGNAL_QUEUE.

Referenced by pg_usleep(), PGSemaphoreLock(), pgwin32_poll_signals(), pgwin32_select(), pgwin32_waitforsinglesocket(), pqsigsetmask(), and WaitEventSetWait().

◆ pgwin32_signal_initialize()

void pgwin32_signal_initialize ( void )

Definition at line 79 of file signal.c.

 {
     int         i;
     HANDLE      signal_thread_handle;
  
     InitializeCriticalSection(&pg_signal_crit_sec);
  
     for (i = 0; i < PG_SIGNAL_COUNT; i++)
     {
         pg_signal_array[i] = SIG_DFL;
         pg_signal_defaults[i] = SIG_IGN;
     }
     pg_signal_mask = 0;
     pg_signal_queue = 0;
  
     /* Create the global event handle used to flag signals */
     pgwin32_signal_event = CreateEvent(NULL, TRUE, FALSE, NULL);
     if (pgwin32_signal_event == NULL)
         ereport(FATAL,
                 (errmsg_internal("could not create signal event: error code %lu", GetLastError())));
  
     /* Create thread for handling signals */
     signal_thread_handle = CreateThread(NULL, 0, pg_signal_thread, NULL, 0, NULL);
     if (signal_thread_handle == NULL)
         ereport(FATAL,
                 (errmsg_internal("could not create signal handler thread")));
  
     /* Create console control handle to pick up Ctrl-C etc */
     if (!SetConsoleCtrlHandler(pg_console_handler, TRUE))
         ereport(FATAL,
                 (errmsg_internal("could not set console control handler")));
 }

References ereport, errmsg_internal(), FATAL, i, pg_console_handler(), pg_signal_array, PG_SIGNAL_COUNT, pg_signal_crit_sec, pg_signal_defaults, pg_signal_mask, pg_signal_queue, pg_signal_thread(), pgwin32_signal_event, SIG_DFL, and SIG_IGN.

Referenced by InitPostmasterChild(), InitStandaloneProcess(), and PostmasterMain().

◆ pqsignal()

pqsigfunc pqsignal	(	int	signum,
		pqsigfunc	handler
	)

Definition at line 180 of file signal.c.

 {
     pqsigfunc   prevfunc;
  
     if (signum >= PG_SIGNAL_COUNT || signum < 0)
         return SIG_ERR;
     prevfunc = pg_signal_array[signum];
     pg_signal_array[signum] = handler;
     return prevfunc;
 }

References pg_signal_array, PG_SIGNAL_COUNT, and SIG_ERR.

Referenced by ApplyLauncherMain(), ApplyWorkerMain(), autoprewarm_database_main(), autoprewarm_main(), AutoVacLauncherMain(), AutoVacWorkerMain(), BackendInitialize(), BackgroundWriterMain(), bootstrap_signals(), CheckpointerMain(), disable_sigpipe_trap(), do_start(), InitializeLatchSupport(), InitializeTimeouts(), InitPostmasterChild(), main(), OpenPipeStream(), ParallelBackupStart(), ParallelWorkerMain(), pg_crc32c_armv8_available(), PgArchiverMain(), plperl_init_interp(), PostgresMain(), PostmasterDeathSignalInit(), PQprint(), restore_sigpipe_trap(), setalarm(), setup_cancel_handler(), setup_signals(), ShutdownLatchSupport(), sigTermHandler(), StartBackgroundWorker(), StartupProcessMain(), SysLoggerMain(), test_shm_mq_main(), trap_sigint_during_startup(), trapsig(), WalReceiverMain(), WalSndSignals(), and WalWriterMain().

◆ pqsigsetmask()

int pqsigsetmask ( int mask )

Definition at line 157 of file signal.c.

 {
     int         prevmask;
  
     prevmask = pg_signal_mask;
     pg_signal_mask = mask;
  
     /*
      * Dispatch any signals queued up right away, in case we have unblocked
      * one or more signals previously queued
      */
     pgwin32_dispatch_queued_signals();
  
     return prevmask;
 }