pqsignal.c File Reference

#include "c.h"
#include <signal.h>
#include <unistd.h>
#include "libpq/pqsignal.h"
#include "miscadmin.h"

Include dependency graph for pqsignal.c:

Go to the source code of this file.

Macros
#define	PG_NSIG   (64) /* XXX: wild guess */
#define	USE_SIGACTION

Functions
	StaticAssertDecl (SIGUSR2< PG_NSIG, "SIGUSR2 >= PG_NSIG")
static void	wrapper_handler (int postgres_signal_arg)
void	pqsignal (int signo, pqsigfunc func)

Variables
static volatile pqsigfunc	pqsignal_handlers [PG_NSIG]

Macro Definition Documentation

PG_NSIG

#define PG_NSIG   (64) /* XXX: wild guess */

Definition at line 63 of file pqsignal.c.

USE_SIGACTION

#define USE_SIGACTION

Definition at line 67 of file pqsignal.c.

Function Documentation

pqsignal()

void pqsignal	(	int	signo,
		pqsigfunc	func
	)

Definition at line 156 of file pqsignal.c.

{
#ifdef USE_SIGACTION
    struct sigaction act;
#else
    void        (*wrapper_func_ptr) (int);
#endif
    bool        is_ign = func == PG_SIG_IGN;
    bool        is_dfl = func == PG_SIG_DFL;
 
    Assert(signo > 0);
    Assert(signo < PG_NSIG);
 
    /* set up indirection handler */
    if (!(is_ign || is_dfl))
    {
        pqsignal_handlers[signo] = func;    /* assumed atomic */
    }
 
    /*
     * Configure system to either ignore/reset the signal handler, or to
     * forward it to wrapper_handler.
     */
#ifdef USE_SIGACTION
    sigemptyset(&act.sa_mask);
    act.sa_flags = SA_RESTART;
 
    if (is_ign)
        act.sa_handler = SIG_IGN;
    else if (is_dfl)
        act.sa_handler = SIG_DFL;
#ifdef USE_SIGINFO
    else
    {
        act.sa_sigaction = wrapper_handler;
        act.sa_flags |= SA_SIGINFO;
    }
#else
    else
        act.sa_handler = wrapper_handler;
#endif
 
#ifdef SA_NOCLDSTOP
    if (signo == SIGCHLD)
        act.sa_flags |= SA_NOCLDSTOP;
#endif
    if (sigaction(signo, &act, NULL) < 0)
        Assert(false);          /* probably indicates coding error */
#else                           /* no USE_SIGACTION */
 
    /*
     * Forward to Windows native signal system, we need to send this though
     * wrapper handler as it it needs to take single argument only.
     */
    if (is_ign)
        wrapper_func_ptr = SIG_IGN;
    else if (is_dfl)
        wrapper_func_ptr = SIG_DFL;
    else
        wrapper_func_ptr = wrapper_handler;
 
    if (signal(signo, wrapper_func_ptr) == SIG_ERR)
        Assert(false);          /* probably indicates coding error */
#endif
}

StaticAssertDecl()

StaticAssertDecl

(

)

wrapper_handler()

static void wrapper_handler ( int  postgres_signal_arg )

static

Definition at line 98 of file pqsignal.c.

{
    int         save_errno = errno;
    pg_signal_info pg_info;
 
    Assert(postgres_signal_arg > 0);
    Assert(postgres_signal_arg < PG_NSIG);
 
#ifndef FRONTEND
 
    /*
     * We expect processes to set MyProcPid before calling pqsignal() or
     * before accepting signals.
     */
    Assert(MyProcPid);
    Assert(MyProcPid != PostmasterPid || !IsUnderPostmaster);
 
    if (unlikely(MyProcPid != (int) getpid()))
    {
        pqsignal(postgres_signal_arg, PG_SIG_DFL);
        raise(postgres_signal_arg);
        return;
    }
#endif
 
#ifdef HAVE_SA_SIGINFO
 
    /*
     * If supported by the system, forward interesting information from the
     * system's extended signal information to our platform independent
     * format.
     */
    pg_info.pid = info->si_pid;
    pg_info.uid = info->si_uid;
#else
 
    /*
     * Otherwise forward values indicating that we do not have the
     * information.
     */
    pg_info.pid = 0;
    pg_info.uid = 0;
#endif
 
    (*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg, &pg_info);
 
    errno = save_errno;
}

Variable Documentation

pqsignal_handlers

volatile pqsigfunc pqsignal_handlers[PG_NSIG]

static

Definition at line 80 of file pqsignal.c.