libpq: Move cancellation related functions to fe-cancel.c

In follow up commits we'll add more functions related to query
cancellations.  This groups those all together instead of mixing them
with the other functions in fe-connect.c.

The formerly static parse_int_param() function had to be exported to
other libpq users, so it's been renamed pqParseIntParam() and moved to a
more reasonable place within fe-connect.c (rather than randomly between
various keepalive-related routines).

Author: Jelte Fennema-Nio <jelte.fennema@microsoft.com>
Discussion: https://postgr.es/m/AM5PR83MB0178D3B31CA1B6EC4A8ECC42F7529@AM5PR83MB0178.EURPRD83.prod.outlook.com

src/interfaces/libpq/Makefile

@@ -30,6 +30,7 @@ endif
 OBJS = \
 	$(WIN32RES) \
 	fe-auth-scram.o \
+	fe-cancel.o \
 	fe-connect.o \
 	fe-exec.o \
 	fe-lobj.o \

src/interfaces/libpq/fe-cancel.c

@@ -0,0 +1,387 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe-cancel.c
+ *	  functions related to setting up a connection to the backend
+ *
+ * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/interfaces/libpq/fe-cancel.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+
+#include "libpq-fe.h"
+#include "libpq-int.h"
+#include "port/pg_bswap.h"
+
+/*
+ * PQgetCancel: get a PGcancel structure corresponding to a connection.
+ *
+ * A copy is needed to be able to cancel a running query from a different
+ * thread. If the same structure is used all structure members would have
+ * to be individually locked (if the entire structure was locked, it would
+ * be impossible to cancel a synchronous query because the structure would
+ * have to stay locked for the duration of the query).
+ */
+PGcancel *
+PQgetCancel(PGconn *conn)
+{
+	PGcancel   *cancel;
+
+	if (!conn)
+		return NULL;
+
+	if (conn->sock == PGINVALID_SOCKET)
+		return NULL;
+
+	cancel = malloc(sizeof(PGcancel));
+	if (cancel == NULL)
+		return NULL;
+
+	memcpy(&cancel->raddr, &conn->raddr, sizeof(SockAddr));
+	cancel->be_pid = conn->be_pid;
+	cancel->be_key = conn->be_key;
+	/* We use -1 to indicate an unset connection option */
+	cancel->pgtcp_user_timeout = -1;
+	cancel->keepalives = -1;
+	cancel->keepalives_idle = -1;
+	cancel->keepalives_interval = -1;
+	cancel->keepalives_count = -1;
+	if (conn->pgtcp_user_timeout != NULL)
+	{
+		if (!pqParseIntParam(conn->pgtcp_user_timeout,
+							 &cancel->pgtcp_user_timeout,
+							 conn, "tcp_user_timeout"))
+			goto fail;
+	}
+	if (conn->keepalives != NULL)
+	{
+		if (!pqParseIntParam(conn->keepalives,
+							 &cancel->keepalives,
+							 conn, "keepalives"))
+			goto fail;
+	}
+	if (conn->keepalives_idle != NULL)
+	{
+		if (!pqParseIntParam(conn->keepalives_idle,
+							 &cancel->keepalives_idle,
+							 conn, "keepalives_idle"))
+			goto fail;
+	}
+	if (conn->keepalives_interval != NULL)
+	{
+		if (!pqParseIntParam(conn->keepalives_interval,
+							 &cancel->keepalives_interval,
+							 conn, "keepalives_interval"))
+			goto fail;
+	}
+	if (conn->keepalives_count != NULL)
+	{
+		if (!pqParseIntParam(conn->keepalives_count,
+							 &cancel->keepalives_count,
+							 conn, "keepalives_count"))
+			goto fail;
+	}
+
+	return cancel;
+
+fail:
+	free(cancel);
+	return NULL;
+}
+
+/* PQfreeCancel: free a cancel structure */
+void
+PQfreeCancel(PGcancel *cancel)
+{
+	free(cancel);
+}
+
+
+/*
+ * Sets an integer socket option on a TCP socket, if the provided value is
+ * not negative.  Returns false if setsockopt fails for some reason.
+ *
+ * CAUTION: This needs to be signal safe, since it's used by PQcancel.
+ */
+#if defined(TCP_USER_TIMEOUT) || !defined(WIN32)
+static bool
+optional_setsockopt(int fd, int protoid, int optid, int value)
+{
+	if (value < 0)
+		return true;
+	if (setsockopt(fd, protoid, optid, (char *) &value, sizeof(value)) < 0)
+		return false;
+	return true;
+}
+#endif
+
+
+/*
+ * PQcancel: request query cancel
+ *
+ * The return value is true if the cancel request was successfully
+ * dispatched, false if not (in which case an error message is available).
+ * Note: successful dispatch is no guarantee that there will be any effect at
+ * the backend.  The application must read the operation result as usual.
+ *
+ * On failure, an error message is stored in *errbuf, which must be of size
+ * errbufsize (recommended size is 256 bytes).  *errbuf is not changed on
+ * success return.
+ *
+ * CAUTION: we want this routine to be safely callable from a signal handler
+ * (for example, an application might want to call it in a SIGINT handler).
+ * This means we cannot use any C library routine that might be non-reentrant.
+ * malloc/free are often non-reentrant, and anything that might call them is
+ * just as dangerous.  We avoid sprintf here for that reason.  Building up
+ * error messages with strcpy/strcat is tedious but should be quite safe.
+ * We also save/restore errno in case the signal handler support doesn't.
+ */
+int
+PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
+{
+	int			save_errno = SOCK_ERRNO;
+	pgsocket	tmpsock = PGINVALID_SOCKET;
+	int			maxlen;
+	struct
+	{
+		uint32		packetlen;
+		CancelRequestPacket cp;
+	}			crp;
+
+	if (!cancel)
+	{
+		strlcpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
+		/* strlcpy probably doesn't change errno, but be paranoid */
+		SOCK_ERRNO_SET(save_errno);
+		return false;
+	}
+
+	/*
+	 * We need to open a temporary connection to the postmaster. Do this with
+	 * only kernel calls.
+	 */
+	if ((tmpsock = socket(cancel->raddr.addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
+	{
+		strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
+		goto cancel_errReturn;
+	}
+
+	/*
+	 * Since this connection will only be used to send a single packet of
+	 * data, we don't need NODELAY.  We also don't set the socket to
+	 * nonblocking mode, because the API definition of PQcancel requires the
+	 * cancel to be sent in a blocking way.
+	 *
+	 * We do set socket options related to keepalives and other TCP timeouts.
+	 * This ensures that this function does not block indefinitely when
+	 * reasonable keepalive and timeout settings have been provided.
+	 */
+	if (cancel->raddr.addr.ss_family != AF_UNIX &&
+		cancel->keepalives != 0)
+	{
+#ifndef WIN32
+		if (!optional_setsockopt(tmpsock, SOL_SOCKET, SO_KEEPALIVE, 1))
+		{
+			strlcpy(errbuf, "PQcancel() -- setsockopt(SO_KEEPALIVE) failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+
+#ifdef PG_TCP_KEEPALIVE_IDLE
+		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, PG_TCP_KEEPALIVE_IDLE,
+								 cancel->keepalives_idle))
+		{
+			strlcpy(errbuf, "PQcancel() -- setsockopt(" PG_TCP_KEEPALIVE_IDLE_STR ") failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+#endif
+
+#ifdef TCP_KEEPINTVL
+		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPINTVL,
+								 cancel->keepalives_interval))
+		{
+			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPINTVL) failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+#endif
+
+#ifdef TCP_KEEPCNT
+		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPCNT,
+								 cancel->keepalives_count))
+		{
+			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPCNT) failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+#endif
+
+#else							/* WIN32 */
+
+#ifdef SIO_KEEPALIVE_VALS
+		if (!pqSetKeepalivesWin32(tmpsock,
+								  cancel->keepalives_idle,
+								  cancel->keepalives_interval))
+		{
+			strlcpy(errbuf, "PQcancel() -- WSAIoctl(SIO_KEEPALIVE_VALS) failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+#endif							/* SIO_KEEPALIVE_VALS */
+#endif							/* WIN32 */
+
+		/* TCP_USER_TIMEOUT works the same way on Unix and Windows */
+#ifdef TCP_USER_TIMEOUT
+		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_USER_TIMEOUT,
+								 cancel->pgtcp_user_timeout))
+		{
+			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_USER_TIMEOUT) failed: ", errbufsize);
+			goto cancel_errReturn;
+		}
+#endif
+	}
+
+retry3:
+	if (connect(tmpsock, (struct sockaddr *) &cancel->raddr.addr,
+				cancel->raddr.salen) < 0)
+	{
+		if (SOCK_ERRNO == EINTR)
+			/* Interrupted system call - we'll just try again */
+			goto retry3;
+		strlcpy(errbuf, "PQcancel() -- connect() failed: ", errbufsize);
+		goto cancel_errReturn;
+	}
+
+	/* Create and send the cancel request packet. */
+
+	crp.packetlen = pg_hton32((uint32) sizeof(crp));
+	crp.cp.cancelRequestCode = (MsgType) pg_hton32(CANCEL_REQUEST_CODE);
+	crp.cp.backendPID = pg_hton32(cancel->be_pid);
+	crp.cp.cancelAuthCode = pg_hton32(cancel->be_key);
+
+retry4:
+	if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
+	{
+		if (SOCK_ERRNO == EINTR)
+			/* Interrupted system call - we'll just try again */
+			goto retry4;
+		strlcpy(errbuf, "PQcancel() -- send() failed: ", errbufsize);
+		goto cancel_errReturn;
+	}
+
+	/*
+	 * Wait for the postmaster to close the connection, which indicates that
+	 * it's processed the request.  Without this delay, we might issue another
+	 * command only to find that our cancel zaps that command instead of the
+	 * one we thought we were canceling.  Note we don't actually expect this
+	 * read to obtain any data, we are just waiting for EOF to be signaled.
+	 */
+retry5:
+	if (recv(tmpsock, (char *) &crp, 1, 0) < 0)
+	{
+		if (SOCK_ERRNO == EINTR)
+			/* Interrupted system call - we'll just try again */
+			goto retry5;
+		/* we ignore other error conditions */
+	}
+
+	/* All done */
+	closesocket(tmpsock);
+	SOCK_ERRNO_SET(save_errno);
+	return true;
+
+cancel_errReturn:
+
+	/*
+	 * Make sure we don't overflow the error buffer. Leave space for the \n at
+	 * the end, and for the terminating zero.
+	 */
+	maxlen = errbufsize - strlen(errbuf) - 2;
+	if (maxlen >= 0)
+	{
+		/*
+		 * We can't invoke strerror here, since it's not signal-safe.  Settle
+		 * for printing the decimal value of errno.  Even that has to be done
+		 * the hard way.
+		 */
+		int			val = SOCK_ERRNO;
+		char		buf[32];
+		char	   *bufp;
+
+		bufp = buf + sizeof(buf) - 1;
+		*bufp = '\0';
+		do
+		{
+			*(--bufp) = (val % 10) + '0';
+			val /= 10;
+		} while (val > 0);
+		bufp -= 6;
+		memcpy(bufp, "error ", 6);
+		strncat(errbuf, bufp, maxlen);
+		strcat(errbuf, "\n");
+	}
+	if (tmpsock != PGINVALID_SOCKET)
+		closesocket(tmpsock);
+	SOCK_ERRNO_SET(save_errno);
+	return false;
+}
+
+/*
+ * PQrequestCancel: old, not thread-safe function for requesting query cancel
+ *
+ * Returns true if able to send the cancel request, false if not.
+ *
+ * On failure, the error message is saved in conn->errorMessage; this means
+ * that this can't be used when there might be other active operations on
+ * the connection object.
+ *
+ * NOTE: error messages will be cut off at the current size of the
+ * error message buffer, since we dare not try to expand conn->errorMessage!
+ */
+int
+PQrequestCancel(PGconn *conn)
+{
+	int			r;
+	PGcancel   *cancel;
+
+	/* Check we have an open connection */
+	if (!conn)
+		return false;
+
+	if (conn->sock == PGINVALID_SOCKET)
+	{
+		strlcpy(conn->errorMessage.data,
+				"PQrequestCancel() -- connection is not open\n",
+				conn->errorMessage.maxlen);
+		conn->errorMessage.len = strlen(conn->errorMessage.data);
+		conn->errorReported = 0;
+
+		return false;
+	}
+
+	cancel = PQgetCancel(conn);
+	if (cancel)
+	{
+		r = PQcancel(cancel, conn->errorMessage.data,
+					 conn->errorMessage.maxlen);
+		PQfreeCancel(cancel);
+	}
+	else
+	{
+		strlcpy(conn->errorMessage.data, "out of memory",
+				conn->errorMessage.maxlen);
+		r = false;
+	}
+
+	if (!r)
+	{
+		conn->errorMessage.len = strlen(conn->errorMessage.data);
+		conn->errorReported = 0;
+	}
+
+	return r;
+}

src/interfaces/libpq/fe-connect.c

@@ -443,8 +443,6 @@ static void pgpassfileWarning(PGconn *conn);
 static void default_threadlock(int acquire);
 static bool sslVerifyProtocolVersion(const char *version);
 static bool sslVerifyProtocolRange(const char *min, const char *max);
-static bool parse_int_param(const char *value, int *result, PGconn *conn,
-							const char *context);
 
 
 /* global variable because fe-auth.c needs to access it */
@@ -2076,52 +2074,6 @@ useKeepalives(PGconn *conn)
 	return val != 0 ? 1 : 0;
 }
 
-/*
- * Parse and try to interpret "value" as an integer value, and if successful,
- * store it in *result, complaining if there is any trailing garbage or an
- * overflow.  This allows any number of leading and trailing whitespaces.
- */
-static bool
-parse_int_param(const char *value, int *result, PGconn *conn,
-				const char *context)
-{
-	char	   *end;
-	long		numval;
-
-	Assert(value != NULL);
-
-	*result = 0;
-
-	/* strtol(3) skips leading whitespaces */
-	errno = 0;
-	numval = strtol(value, &end, 10);
-
-	/*
-	 * If no progress was done during the parsing or an error happened, fail.
-	 * This tests properly for overflows of the result.
-	 */
-	if (value == end || errno != 0 || numval != (int) numval)
-		goto error;
-
-	/*
-	 * Skip any trailing whitespace; if anything but whitespace remains before
-	 * the terminating character, fail
-	 */
-	while (*end != '\0' && isspace((unsigned char) *end))
-		end++;
-
-	if (*end != '\0')
-		goto error;
-
-	*result = numval;
-	return true;
-
-error:
-	libpq_append_conn_error(conn, "invalid integer value \"%s\" for connection option \"%s\"",
-							value, context);
-	return false;
-}
-
 #ifndef WIN32
 /*
  * Set the keepalive idle timer.
@@ -2134,7 +2086,7 @@ setKeepalivesIdle(PGconn *conn)
 	if (conn->keepalives_idle == NULL)
 		return 1;
 
-	if (!parse_int_param(conn->keepalives_idle, &idle, conn,
+	if (!pqParseIntParam(conn->keepalives_idle, &idle, conn,
 						 "keepalives_idle"))
 		return 0;
 	if (idle < 0)
@@ -2168,7 +2120,7 @@ setKeepalivesInterval(PGconn *conn)
 	if (conn->keepalives_interval == NULL)
 		return 1;
 
-	if (!parse_int_param(conn->keepalives_interval, &interval, conn,
+	if (!pqParseIntParam(conn->keepalives_interval, &interval, conn,
 						 "keepalives_interval"))
 		return 0;
 	if (interval < 0)
@@ -2203,7 +2155,7 @@ setKeepalivesCount(PGconn *conn)
 	if (conn->keepalives_count == NULL)
 		return 1;
 
-	if (!parse_int_param(conn->keepalives_count, &count, conn,
+	if (!pqParseIntParam(conn->keepalives_count, &count, conn,
 						 "keepalives_count"))
 		return 0;
 	if (count < 0)
@@ -2233,8 +2185,8 @@ setKeepalivesCount(PGconn *conn)
  *
  * CAUTION: This needs to be signal safe, since it's used by PQcancel.
  */
-static int
+int
-setKeepalivesWin32(pgsocket sock, int idle, int interval)
+pqSetKeepalivesWin32(pgsocket sock, int idle, int interval)
 {
 	struct tcp_keepalive ka;
 	DWORD		retsize;
@@ -2269,15 +2221,15 @@ prepKeepalivesWin32(PGconn *conn)
 	int			interval = -1;
 
 	if (conn->keepalives_idle &&
-		!parse_int_param(conn->keepalives_idle, &idle, conn,
+		!pqParseIntParam(conn->keepalives_idle, &idle, conn,
 						 "keepalives_idle"))
 		return 0;
 	if (conn->keepalives_interval &&
-		!parse_int_param(conn->keepalives_interval, &interval, conn,
+		!pqParseIntParam(conn->keepalives_interval, &interval, conn,
 						 "keepalives_interval"))
 		return 0;
 
-	if (!setKeepalivesWin32(conn->sock, idle, interval))
+	if (!pqSetKeepalivesWin32(conn->sock, idle, interval))
 	{
 		libpq_append_conn_error(conn, "%s(%s) failed: error code %d",
 								"WSAIoctl", "SIO_KEEPALIVE_VALS",
@@ -2300,7 +2252,7 @@ setTCPUserTimeout(PGconn *conn)
 	if (conn->pgtcp_user_timeout == NULL)
 		return 1;
 
-	if (!parse_int_param(conn->pgtcp_user_timeout, &timeout, conn,
+	if (!pqParseIntParam(conn->pgtcp_user_timeout, &timeout, conn,
 						 "tcp_user_timeout"))
 		return 0;
 
@@ -2418,7 +2370,7 @@ connectDBComplete(PGconn *conn)
 	 */
 	if (conn->connect_timeout != NULL)
 	{
-		if (!parse_int_param(conn->connect_timeout, &timeout, conn,
+		if (!pqParseIntParam(conn->connect_timeout, &timeout, conn,
 							 "connect_timeout"))
 		{
 			/* mark the connection as bad to report the parsing failure */
@@ -2666,7 +2618,7 @@ keep_going:						/* We will come back to here until there is
 			thisport = DEF_PGPORT;
 		else
 		{
-			if (!parse_int_param(ch->port, &thisport, conn, "port"))
+			if (!pqParseIntParam(ch->port, &thisport, conn, "port"))
 				goto error_return;
 
 			if (thisport < 1 || thisport > 65535)
@@ -4694,373 +4646,6 @@ PQresetPoll(PGconn *conn)
 	return PGRES_POLLING_FAILED;
 }
 
-/*
- * PQgetCancel: get a PGcancel structure corresponding to a connection.
- *
- * A copy is needed to be able to cancel a running query from a different
- * thread. If the same structure is used all structure members would have
- * to be individually locked (if the entire structure was locked, it would
- * be impossible to cancel a synchronous query because the structure would
- * have to stay locked for the duration of the query).
- */
-PGcancel *
-PQgetCancel(PGconn *conn)
-{
-	PGcancel   *cancel;
-
-	if (!conn)
-		return NULL;
-
-	if (conn->sock == PGINVALID_SOCKET)
-		return NULL;
-
-	cancel = malloc(sizeof(PGcancel));
-	if (cancel == NULL)
-		return NULL;
-
-	memcpy(&cancel->raddr, &conn->raddr, sizeof(SockAddr));
-	cancel->be_pid = conn->be_pid;
-	cancel->be_key = conn->be_key;
-	/* We use -1 to indicate an unset connection option */
-	cancel->pgtcp_user_timeout = -1;
-	cancel->keepalives = -1;
-	cancel->keepalives_idle = -1;
-	cancel->keepalives_interval = -1;
-	cancel->keepalives_count = -1;
-	if (conn->pgtcp_user_timeout != NULL)
-	{
-		if (!parse_int_param(conn->pgtcp_user_timeout,
-							 &cancel->pgtcp_user_timeout,
-							 conn, "tcp_user_timeout"))
-			goto fail;
-	}
-	if (conn->keepalives != NULL)
-	{
-		if (!parse_int_param(conn->keepalives,
-							 &cancel->keepalives,
-							 conn, "keepalives"))
-			goto fail;
-	}
-	if (conn->keepalives_idle != NULL)
-	{
-		if (!parse_int_param(conn->keepalives_idle,
-							 &cancel->keepalives_idle,
-							 conn, "keepalives_idle"))
-			goto fail;
-	}
-	if (conn->keepalives_interval != NULL)
-	{
-		if (!parse_int_param(conn->keepalives_interval,
-							 &cancel->keepalives_interval,
-							 conn, "keepalives_interval"))
-			goto fail;
-	}
-	if (conn->keepalives_count != NULL)
-	{
-		if (!parse_int_param(conn->keepalives_count,
-							 &cancel->keepalives_count,
-							 conn, "keepalives_count"))
-			goto fail;
-	}
-
-	return cancel;
-
-fail:
-	free(cancel);
-	return NULL;
-}
-
-/* PQfreeCancel: free a cancel structure */
-void
-PQfreeCancel(PGcancel *cancel)
-{
-	free(cancel);
-}
-
-
-/*
- * Sets an integer socket option on a TCP socket, if the provided value is
- * not negative.  Returns false if setsockopt fails for some reason.
- *
- * CAUTION: This needs to be signal safe, since it's used by PQcancel.
- */
-#if defined(TCP_USER_TIMEOUT) || !defined(WIN32)
-static bool
-optional_setsockopt(int fd, int protoid, int optid, int value)
-{
-	if (value < 0)
-		return true;
-	if (setsockopt(fd, protoid, optid, (char *) &value, sizeof(value)) < 0)
-		return false;
-	return true;
-}
-#endif
-
-
-/*
- * PQcancel: request query cancel
- *
- * The return value is true if the cancel request was successfully
- * dispatched, false if not (in which case an error message is available).
- * Note: successful dispatch is no guarantee that there will be any effect at
- * the backend.  The application must read the operation result as usual.
- *
- * On failure, an error message is stored in *errbuf, which must be of size
- * errbufsize (recommended size is 256 bytes).  *errbuf is not changed on
- * success return.
- *
- * CAUTION: we want this routine to be safely callable from a signal handler
- * (for example, an application might want to call it in a SIGINT handler).
- * This means we cannot use any C library routine that might be non-reentrant.
- * malloc/free are often non-reentrant, and anything that might call them is
- * just as dangerous.  We avoid sprintf here for that reason.  Building up
- * error messages with strcpy/strcat is tedious but should be quite safe.
- * We also save/restore errno in case the signal handler support doesn't.
- */
-int
-PQcancel(PGcancel *cancel, char *errbuf, int errbufsize)
-{
-	int			save_errno = SOCK_ERRNO;
-	pgsocket	tmpsock = PGINVALID_SOCKET;
-	int			maxlen;
-	struct
-	{
-		uint32		packetlen;
-		CancelRequestPacket cp;
-	}			crp;
-
-	if (!cancel)
-	{
-		strlcpy(errbuf, "PQcancel() -- no cancel object supplied", errbufsize);
-		/* strlcpy probably doesn't change errno, but be paranoid */
-		SOCK_ERRNO_SET(save_errno);
-		return false;
-	}
-
-	/*
-	 * We need to open a temporary connection to the postmaster. Do this with
-	 * only kernel calls.
-	 */
-	if ((tmpsock = socket(cancel->raddr.addr.ss_family, SOCK_STREAM, 0)) == PGINVALID_SOCKET)
-	{
-		strlcpy(errbuf, "PQcancel() -- socket() failed: ", errbufsize);
-		goto cancel_errReturn;
-	}
-
-	/*
-	 * Since this connection will only be used to send a single packet of
-	 * data, we don't need NODELAY.  We also don't set the socket to
-	 * nonblocking mode, because the API definition of PQcancel requires the
-	 * cancel to be sent in a blocking way.
-	 *
-	 * We do set socket options related to keepalives and other TCP timeouts.
-	 * This ensures that this function does not block indefinitely when
-	 * reasonable keepalive and timeout settings have been provided.
-	 */
-	if (cancel->raddr.addr.ss_family != AF_UNIX &&
-		cancel->keepalives != 0)
-	{
-#ifndef WIN32
-		if (!optional_setsockopt(tmpsock, SOL_SOCKET, SO_KEEPALIVE, 1))
-		{
-			strlcpy(errbuf, "PQcancel() -- setsockopt(SO_KEEPALIVE) failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-
-#ifdef PG_TCP_KEEPALIVE_IDLE
-		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, PG_TCP_KEEPALIVE_IDLE,
-								 cancel->keepalives_idle))
-		{
-			strlcpy(errbuf, "PQcancel() -- setsockopt(" PG_TCP_KEEPALIVE_IDLE_STR ") failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-#endif
-
-#ifdef TCP_KEEPINTVL
-		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPINTVL,
-								 cancel->keepalives_interval))
-		{
-			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPINTVL) failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-#endif
-
-#ifdef TCP_KEEPCNT
-		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_KEEPCNT,
-								 cancel->keepalives_count))
-		{
-			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_KEEPCNT) failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-#endif
-
-#else							/* WIN32 */
-
-#ifdef SIO_KEEPALIVE_VALS
-		if (!setKeepalivesWin32(tmpsock,
-								cancel->keepalives_idle,
-								cancel->keepalives_interval))
-		{
-			strlcpy(errbuf, "PQcancel() -- WSAIoctl(SIO_KEEPALIVE_VALS) failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-#endif							/* SIO_KEEPALIVE_VALS */
-#endif							/* WIN32 */
-
-		/* TCP_USER_TIMEOUT works the same way on Unix and Windows */
-#ifdef TCP_USER_TIMEOUT
-		if (!optional_setsockopt(tmpsock, IPPROTO_TCP, TCP_USER_TIMEOUT,
-								 cancel->pgtcp_user_timeout))
-		{
-			strlcpy(errbuf, "PQcancel() -- setsockopt(TCP_USER_TIMEOUT) failed: ", errbufsize);
-			goto cancel_errReturn;
-		}
-#endif
-	}
-
-retry3:
-	if (connect(tmpsock, (struct sockaddr *) &cancel->raddr.addr,
-				cancel->raddr.salen) < 0)
-	{
-		if (SOCK_ERRNO == EINTR)
-			/* Interrupted system call - we'll just try again */
-			goto retry3;
-		strlcpy(errbuf, "PQcancel() -- connect() failed: ", errbufsize);
-		goto cancel_errReturn;
-	}
-
-	/* Create and send the cancel request packet. */
-
-	crp.packetlen = pg_hton32((uint32) sizeof(crp));
-	crp.cp.cancelRequestCode = (MsgType) pg_hton32(CANCEL_REQUEST_CODE);
-	crp.cp.backendPID = pg_hton32(cancel->be_pid);
-	crp.cp.cancelAuthCode = pg_hton32(cancel->be_key);
-
-retry4:
-	if (send(tmpsock, (char *) &crp, sizeof(crp), 0) != (int) sizeof(crp))
-	{
-		if (SOCK_ERRNO == EINTR)
-			/* Interrupted system call - we'll just try again */
-			goto retry4;
-		strlcpy(errbuf, "PQcancel() -- send() failed: ", errbufsize);
-		goto cancel_errReturn;
-	}
-
-	/*
-	 * Wait for the postmaster to close the connection, which indicates that
-	 * it's processed the request.  Without this delay, we might issue another
-	 * command only to find that our cancel zaps that command instead of the
-	 * one we thought we were canceling.  Note we don't actually expect this
-	 * read to obtain any data, we are just waiting for EOF to be signaled.
-	 */
-retry5:
-	if (recv(tmpsock, (char *) &crp, 1, 0) < 0)
-	{
-		if (SOCK_ERRNO == EINTR)
-			/* Interrupted system call - we'll just try again */
-			goto retry5;
-		/* we ignore other error conditions */
-	}
-
-	/* All done */
-	closesocket(tmpsock);
-	SOCK_ERRNO_SET(save_errno);
-	return true;
-
-cancel_errReturn:
-
-	/*
-	 * Make sure we don't overflow the error buffer. Leave space for the \n at
-	 * the end, and for the terminating zero.
-	 */
-	maxlen = errbufsize - strlen(errbuf) - 2;
-	if (maxlen >= 0)
-	{
-		/*
-		 * We can't invoke strerror here, since it's not signal-safe.  Settle
-		 * for printing the decimal value of errno.  Even that has to be done
-		 * the hard way.
-		 */
-		int			val = SOCK_ERRNO;
-		char		buf[32];
-		char	   *bufp;
-
-		bufp = buf + sizeof(buf) - 1;
-		*bufp = '\0';
-		do
-		{
-			*(--bufp) = (val % 10) + '0';
-			val /= 10;
-		} while (val > 0);
-		bufp -= 6;
-		memcpy(bufp, "error ", 6);
-		strncat(errbuf, bufp, maxlen);
-		strcat(errbuf, "\n");
-	}
-	if (tmpsock != PGINVALID_SOCKET)
-		closesocket(tmpsock);
-	SOCK_ERRNO_SET(save_errno);
-	return false;
-}
-
-
-/*
- * PQrequestCancel: old, not thread-safe function for requesting query cancel
- *
- * Returns true if able to send the cancel request, false if not.
- *
- * On failure, the error message is saved in conn->errorMessage; this means
- * that this can't be used when there might be other active operations on
- * the connection object.
- *
- * NOTE: error messages will be cut off at the current size of the
- * error message buffer, since we dare not try to expand conn->errorMessage!
- */
-int
-PQrequestCancel(PGconn *conn)
-{
-	int			r;
-	PGcancel   *cancel;
-
-	/* Check we have an open connection */
-	if (!conn)
-		return false;
-
-	if (conn->sock == PGINVALID_SOCKET)
-	{
-		strlcpy(conn->errorMessage.data,
-				"PQrequestCancel() -- connection is not open\n",
-				conn->errorMessage.maxlen);
-		conn->errorMessage.len = strlen(conn->errorMessage.data);
-		conn->errorReported = 0;
-
-		return false;
-	}
-
-	cancel = PQgetCancel(conn);
-	if (cancel)
-	{
-		r = PQcancel(cancel, conn->errorMessage.data,
-					 conn->errorMessage.maxlen);
-		PQfreeCancel(cancel);
-	}
-	else
-	{
-		strlcpy(conn->errorMessage.data, "out of memory",
-				conn->errorMessage.maxlen);
-		r = false;
-	}
-
-	if (!r)
-	{
-		conn->errorMessage.len = strlen(conn->errorMessage.data);
-		conn->errorReported = 0;
-	}
-
-	return r;
-}
-
-
 /*
  * pqPacketSend() -- convenience routine to send a message to server.
  *
@@ -7774,6 +7359,52 @@ pqGetHomeDirectory(char *buf, int bufsize)
 #endif
 }
 
+/*
+ * Parse and try to interpret "value" as an integer value, and if successful,
+ * store it in *result, complaining if there is any trailing garbage or an
+ * overflow.  This allows any number of leading and trailing whitespaces.
+ */
+bool
+pqParseIntParam(const char *value, int *result, PGconn *conn,
+				const char *context)
+{
+	char	   *end;
+	long		numval;
+
+	Assert(value != NULL);
+
+	*result = 0;
+
+	/* strtol(3) skips leading whitespaces */
+	errno = 0;
+	numval = strtol(value, &end, 10);
+
+	/*
+	 * If no progress was done during the parsing or an error happened, fail.
+	 * This tests properly for overflows of the result.
+	 */
+	if (value == end || errno != 0 || numval != (int) numval)
+		goto error;
+
+	/*
+	 * Skip any trailing whitespace; if anything but whitespace remains before
+	 * the terminating character, fail
+	 */
+	while (*end != '\0' && isspace((unsigned char) *end))
+		end++;
+
+	if (*end != '\0')
+		goto error;
+
+	*result = numval;
+	return true;
+
+error:
+	libpq_append_conn_error(conn, "invalid integer value \"%s\" for connection option \"%s\"",
+							value, context);
+	return false;
+}
+
 /*
  * To keep the API consistent, the locking stubs are always provided, even
  * if they are not required.

src/interfaces/libpq/libpq-int.h

@@ -675,9 +675,14 @@ extern char *const pgresStatus[];
 /* === in fe-connect.c === */
 
 extern void pqDropConnection(PGconn *conn, bool flushInput);
+#if defined(WIN32) && defined(SIO_KEEPALIVE_VALS)
+extern int	pqSetKeepalivesWin32(pgsocket sock, int idle, int interval);
+#endif
 extern int	pqPacketSend(PGconn *conn, char pack_type,
 						 const void *buf, size_t buf_len);
 extern bool pqGetHomeDirectory(char *buf, int bufsize);
+extern bool pqParseIntParam(const char *value, int *result, PGconn *conn,
+							const char *context);
 
 extern pgthreadlock_t pg_g_threadlock;
 

src/interfaces/libpq/meson.build

@@ -6,6 +6,7 @@
 libpq_sources = files(
   'fe-auth-scram.c',
   'fe-auth.c',
+  'fe-cancel.c',
   'fe-connect.c',
   'fe-exec.c',
   'fe-lobj.c',