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From: Tom Lane <tgl@sss.pgh.pa.us>

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Making PQrequestCancel safe to call in a signal handler turned out to be
much easier than I feared.  So here are the diffs.

Some notes:
  * I modified the postmaster's packet "iodone" callback interface to allow
    the callback routine to return a continue-or-drop-connection return
    code; this was necessary to allow the connection to be closed after
    receiving a Cancel, rather than proceeding to launch a new backend...
    Being a neatnik, I also made the iodone proc have a typechecked
    parameter list.
  * I deleted all code I could find that had to do with OOB.
  * I made some edits to ensure that all signals mentioned in the code
    are referred to symbolically not by numbers ("SIGUSR2" not "2").
    I think Bruce may have already done at least some of the same edits;
    I hope that merging these patches is not too painful.
This commit is contained in:
Marc G. Fournier
1998-07-09 03:29:11 +00:00
parent 8bf61820f0
commit a0659e3e2c
20 changed files with 597 additions and 287 deletions
Download Patch File Download Diff File Expand all files Collapse all files

124
src/backend/postmaster/postmaster.c
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@@ -10,7 +10,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.92 1998/06/27 14:06:40 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/postmaster/postmaster.c,v 1.93 1998/07/09 03:28:47 scrappy Exp $
*
* NOTES
*
@@ -206,7 +206,6 @@ static int orgsigmask = sigblock(0);
*/
static unsigned int random_seed = 0;
long MyCancelKey = 0;
extern char *optarg;
extern int optind,
@@ -228,7 +227,8 @@ static void ExitPostmaster(int status);
static void usage(const char *);
static int ServerLoop(void);
static int BackendStartup(Port *port);
static void readStartupPacket(char *arg, PacketLen len, char *pkt);
static int readStartupPacket(void *arg, PacketLen len, void *pkt);
static int processCancelRequest(Port *port, PacketLen len, void *pkt);
static int initMasks(fd_set *rmask, fd_set *wmask);
static long PostmasterRandom(void);
static void RandomSalt(char *salt);
@@ -518,6 +518,10 @@ PostmasterMain(int argc, char *argv[])
if (silentflag)
pmdaemonize();
/*
* Set up signal handlers for the postmaster process.
*/
pqsignal(SIGINT, pmdie);
pqsignal(SIGCHLD, reaper);
pqsignal(SIGTTIN, SIG_IGN);
@@ -657,14 +661,14 @@ ServerLoop(void)
(port = ConnCreate(ServerSock_UNIX)) != NULL)
PacketReceiveSetup(&port->pktInfo,
readStartupPacket,
(char *) port);
(void *) port);
if (ServerSock_INET != INVALID_SOCK &&
FD_ISSET(ServerSock_INET, &rmask) &&
(port = ConnCreate(ServerSock_INET)) != NULL)
PacketReceiveSetup(&port->pktInfo,
readStartupPacket,
(char *) port);
(void *) port);
/* Build up new masks for select(). */
@@ -790,8 +794,8 @@ initMasks(fd_set *rmask, fd_set *wmask)
* Called when the startup packet has been read.
*/
static void
readStartupPacket(char *arg, PacketLen len, char *pkt)
static int
readStartupPacket(void *arg, PacketLen len, void *pkt)
{
Port *port;
StartupPacket *si;
@@ -799,6 +803,28 @@ readStartupPacket(char *arg, PacketLen len, char *pkt)
port = (Port *) arg;
si = (StartupPacket *) pkt;
/* The first field is either a protocol version number or
* a special request code.
*/
port->proto = ntohl(si->protoVersion);
if (port->proto == CANCEL_REQUEST_CODE)
return processCancelRequest(port, len, pkt);
/* Could add additional special packet types here */
/* Check we can handle the protocol the frontend is using. */
if (PG_PROTOCOL_MAJOR(port->proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
PG_PROTOCOL_MAJOR(port->proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) ||
(PG_PROTOCOL_MAJOR(port->proto) == PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) &&
PG_PROTOCOL_MINOR(port->proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST)))
{
PacketSendError(&port->pktInfo, "Unsupported frontend protocol.");
return STATUS_OK; /* don't close the connection yet */
}
/*
* Get the parameters from the startup packet as C strings. The
* packet destination was cleared first so a short packet has zeros
@@ -815,31 +841,74 @@ readStartupPacket(char *arg, PacketLen len, char *pkt)
if (port->database[0] == '\0')
StrNCpy(port->database, si->user, sizeof(port->database) - 1);
/* Check we can handle the protocol the frontend is using. */
port->proto = ntohl(si->protoVersion);
if (PG_PROTOCOL_MAJOR(port->proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) ||
PG_PROTOCOL_MAJOR(port->proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) ||
(PG_PROTOCOL_MAJOR(port->proto) == PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST) &&
PG_PROTOCOL_MINOR(port->proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST)))
{
PacketSendError(&port->pktInfo, "Unsupported frontend protocol.");
return;
}
/* Check a user name was given. */
if (port->user[0] == '\0')
{
PacketSendError(&port->pktInfo,
"No Postgres username specified in startup packet.");
return;
return STATUS_OK; /* don't close the connection yet */
}
/* Start the authentication itself. */
be_recvauth(port);
return STATUS_OK; /* don't close the connection yet */
}
/*
* The client has sent a cancel request packet, not a normal
* start-a-new-backend packet. Perform the necessary processing.
* Note that in any case, we return STATUS_ERROR to close the
* connection immediately. Nothing is sent back to the client.
*/
static int
processCancelRequest(Port *port, PacketLen len, void *pkt)
{
CancelRequestPacket *canc = (CancelRequestPacket *) pkt;
int backendPID;
long cancelAuthCode;
Dlelem *curr;
Backend *bp;
backendPID = (int) ntohl(canc->backendPID);
cancelAuthCode = (long) ntohl(canc->cancelAuthCode);
/* See if we have a matching backend */
for (curr = DLGetHead(BackendList); curr; curr = DLGetSucc(curr))
{
bp = (Backend *) DLE_VAL(curr);
if (bp->pid == backendPID)
{
if (bp->cancel_key == cancelAuthCode)
{
/* Found a match; signal that backend to cancel current op */
if (DebugLvl)
fprintf(stderr, "%s: processCancelRequest: sending SIGINT to process %d\n",
progname, bp->pid);
kill(bp->pid, SIGINT);
}
else
{
/* Right PID, wrong key: no way, Jose */
if (DebugLvl)
fprintf(stderr, "%s: processCancelRequest: bad key in cancel request for process %d\n",
progname, bp->pid);
}
return STATUS_ERROR;
}
}
/* No matching backend */
if (DebugLvl)
fprintf(stderr, "%s: processCancelRequest: bad PID in cancel request for process %d\n",
progname, backendPID);
return STATUS_ERROR;
}
@@ -1221,6 +1290,8 @@ DoBackend(Port *port)
char dbbuf[ARGV_SIZE + 1];
int ac = 0;
int i;
struct timeval now;
struct timezone tz;
/*
* Let's clean up ourselves as the postmaster child
@@ -1254,7 +1325,16 @@ DoBackend(Port *port)
if (NetServer)
StreamClose(ServerSock_INET);
StreamClose(ServerSock_UNIX);
/*
* Don't want backend to be able to see the postmaster random number
* generator state. We have to clobber the static random_seed *and*
* start a new random sequence in the random() library function.
*/
random_seed = 0;
gettimeofday(&now, &tz);
srandom(now.tv_usec);
/* Now, on to standard postgres stuff */
MyProcPid = getpid();