Arrange to ignore SIGPIPE during SSL_read() and SSL_shutdown(), as these

are known to write on the socket sometimes and thus we are vulnerable to
being killed by the signal if the server happens to go away unexpectedly.
Noticed while trying (futilely) to reproduce bug #3902.

This bug has been there all along, but since the situation is usually
only of interest to developers, I chose not to back-patch the changes.

src/interfaces/libpq/fe-secure.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.101 2008/01/01 19:46:00 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.102 2008/01/29 02:03:39 tgl Exp $
  *
  * NOTES
  *	  [ Most of these notes are wrong/obsolete, but perhaps not all ]
@@ -162,6 +162,50 @@ static bool pq_initssllib = true;
 static SSL_CTX *SSL_context = NULL;
 #endif
 
+/*
+ * Macros to handle disabling and then restoring the state of SIGPIPE handling.
+ * Note that DISABLE_SIGPIPE() must appear at the start of a block.
+ */
+
+#ifndef WIN32
+#ifdef ENABLE_THREAD_SAFETY
+
+#define DISABLE_SIGPIPE(failaction) \
+	sigset_t	osigmask; \
+	bool		sigpipe_pending; \
+	bool		got_epipe = false; \
+\
+	if (pq_block_sigpipe(&osigmask, &sigpipe_pending) < 0) \
+		failaction
+
+#define REMEMBER_EPIPE(cond) \
+	do { \
+		if (cond) \
+			got_epipe = true; \
+	} while (0)
+
+#define RESTORE_SIGPIPE() \
+	pq_reset_sigpipe(&osigmask, sigpipe_pending, got_epipe)
+
+#else	/* !ENABLE_THREAD_SAFETY */
+
+#define DISABLE_SIGPIPE(failaction) \
+	pqsigfunc	oldsighandler = pqsignal(SIGPIPE, SIG_IGN)
+
+#define REMEMBER_EPIPE(cond)
+
+#define RESTORE_SIGPIPE() \
+	pqsignal(SIGPIPE, oldsighandler)
+
+#endif	/* ENABLE_THREAD_SAFETY */
+#else	/* WIN32 */
+
+#define DISABLE_SIGPIPE(failaction)
+#define REMEMBER_EPIPE(cond)
+#define RESTORE_SIGPIPE()
+
+#endif	/* WIN32 */
+
 /* ------------------------------------------------------------ */
 /*			 Procedures common to all secure sessions			*/
 /* ------------------------------------------------------------ */
@@ -268,6 +312,9 @@ pqsecure_read(PGconn *conn, void *ptr, size_t len)
 	{
 		int			err;
 
+		/* SSL_read can write to the socket, so we need to disable SIGPIPE */
+		DISABLE_SIGPIPE(return -1);
+
 rloop:
 		n = SSL_read(conn->ssl, ptr, len);
 		err = SSL_get_error(conn->ssl, n);
@@ -292,9 +339,12 @@ rloop:
 					char		sebuf[256];
 
 					if (n == -1)
+					{
+						REMEMBER_EPIPE(SOCK_ERRNO == EPIPE);
 						printfPQExpBuffer(&conn->errorMessage,
 									libpq_gettext("SSL SYSCALL error: %s\n"),
 							SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
+					}
 					else
 					{
 						printfPQExpBuffer(&conn->errorMessage,
@@ -325,6 +375,8 @@ rloop:
 				n = -1;
 				break;
 		}
+
+		RESTORE_SIGPIPE();
 	}
 	else
 #endif
@@ -341,19 +393,7 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 {
 	ssize_t		n;
 
-#ifndef WIN32
-#ifdef ENABLE_THREAD_SAFETY
-	sigset_t	osigmask;
-	bool		sigpipe_pending;
-	bool		got_epipe = false;
-
-
-	if (pq_block_sigpipe(&osigmask, &sigpipe_pending) < 0)
-		return -1;
-#else
-	pqsigfunc	oldsighandler = pqsignal(SIGPIPE, SIG_IGN);
-#endif   /* ENABLE_THREAD_SAFETY */
-#endif   /* WIN32 */
+	DISABLE_SIGPIPE(return -1);
 
 #ifdef USE_SSL
 	if (conn->ssl)
@@ -384,10 +424,7 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 
 					if (n == -1)
 					{
-#if defined(ENABLE_THREAD_SAFETY) && !defined(WIN32)
-						if (SOCK_ERRNO == EPIPE)
-							got_epipe = true;
-#endif
+						REMEMBER_EPIPE(SOCK_ERRNO == EPIPE);
 						printfPQExpBuffer(&conn->errorMessage,
 									libpq_gettext("SSL SYSCALL error: %s\n"),
 							SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
@@ -426,19 +463,10 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 #endif
 	{
 		n = send(conn->sock, ptr, len, 0);
-#if defined(ENABLE_THREAD_SAFETY) && !defined(WIN32)
-		if (n < 0 && SOCK_ERRNO == EPIPE)
-			got_epipe = true;
-#endif
+		REMEMBER_EPIPE(n < 0 && SOCK_ERRNO == EPIPE);
 	}
 
-#ifndef WIN32
-#ifdef ENABLE_THREAD_SAFETY
-	pq_reset_sigpipe(&osigmask, sigpipe_pending, got_epipe);
-#else
-	pqsignal(SIGPIPE, oldsighandler);
-#endif   /* ENABLE_THREAD_SAFETY */
-#endif   /* WIN32 */
+	RESTORE_SIGPIPE();
 
 	return n;
 }
@@ -1092,9 +1120,13 @@ close_SSL(PGconn *conn)
 {
 	if (conn->ssl)
 	{
+		DISABLE_SIGPIPE((void) 0);
 		SSL_shutdown(conn->ssl);
 		SSL_free(conn->ssl);
 		conn->ssl = NULL;
+		/* We have to assume we got EPIPE */
+		REMEMBER_EPIPE(true);
+		RESTORE_SIGPIPE();
 	}
 
 	if (conn->peer)
@@ -1167,6 +1199,7 @@ PQgetssl(PGconn *conn)
 }
 #endif   /* USE_SSL */
 
+
 #if defined(ENABLE_THREAD_SAFETY) && !defined(WIN32)
 
 /*
@@ -1251,4 +1284,4 @@ pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending, bool got_epipe)
 	SOCK_ERRNO_SET(save_errno);
 }
 
-#endif   /* ENABLE_THREAD_SAFETY */
+#endif   /* ENABLE_THREAD_SAFETY && !WIN32 */