Code review for recent libpq changes. Be more careful about error

handling in SIGPIPE processing; avoid unnecessary pollution of application
link-symbol namespace; spell 'pointer to function' in the conventional
way.

src/interfaces/libpq/fe-connect.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.291 2004/12/02 15:32:54 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-connect.c,v 1.292 2004/12/02 23:20:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -202,6 +202,11 @@ static int parseServiceInfo(PQconninfoOption *options,
 static char *pwdfMatchesString(char *buf, char *token);
 static char *PasswordFromFile(char *hostname, char *port, char *dbname,
 				 char *username);
+static void default_threadlock(int acquire);
+
+
+/* global variable because fe-auth.c needs to access it */
+pgthreadlock_t pg_g_threadlock = default_threadlock;
 
 
 /*
@@ -3276,16 +3281,6 @@ PasswordFromFile(char *hostname, char *port, char *dbname, char *username)
  * if they are not required.
  */
 
-void
-PQinitSSL(int do_init)
-{
-#ifdef USE_SSL
-	pq_initssllib = do_init;
-#endif
-}
-
-static pgthreadlock_t default_threadlock;
-
 static void
 default_threadlock(int acquire)
 {
@@ -3313,17 +3308,15 @@ default_threadlock(int acquire)
 #endif
 }
 
-pgthreadlock_t *g_threadlock = default_threadlock;
-
-pgthreadlock_t *
-PQregisterThreadLock(pgthreadlock_t *newhandler)
+pgthreadlock_t
+PQregisterThreadLock(pgthreadlock_t newhandler)
 {
-	pgthreadlock_t *prev;
+	pgthreadlock_t prev = pg_g_threadlock;
 
-	prev = g_threadlock;
 	if (newhandler)
-		g_threadlock = newhandler;
+		pg_g_threadlock = newhandler;
 	else
-		g_threadlock = default_threadlock;
+		pg_g_threadlock = default_threadlock;
+
 	return prev;
 }

src/interfaces/libpq/fe-print.c

@@ -10,7 +10,7 @@
  * didn't really belong there.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-print.c,v 1.56 2004/12/02 15:32:54 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-print.c,v 1.57 2004/12/02 23:20:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -193,7 +193,7 @@ PQprint(FILE *fout,
 				{
 					usePipe = 1;
 #ifdef ENABLE_THREAD_SAFETY
-					pq_block_sigpipe(&osigset, &sigpipe_pending);
+					if (pq_block_sigpipe(&osigset, &sigpipe_pending) == 0)
 						sigpipe_masked = true;
 #else
 #ifndef WIN32
@@ -316,8 +316,9 @@ PQprint(FILE *fout,
 			pclose(fout);
 #endif
 #ifdef ENABLE_THREAD_SAFETY
+			/* we can't easily verify if EPIPE occurred, so say it did */
 			if (sigpipe_masked)
-				pq_reset_sigpipe(&osigset, sigpipe_pending);
+				pq_reset_sigpipe(&osigset, sigpipe_pending, true);
 #else
 #ifndef WIN32
 			pqsignal(SIGPIPE, oldsigpipehandler);

src/interfaces/libpq/fe-secure.c

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.58 2004/12/02 15:32:54 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-secure.c,v 1.59 2004/12/02 23:20:21 tgl Exp $
  *
  * NOTES
  *	  [ Most of these notes are wrong/obsolete, but perhaps not all ]
@@ -147,7 +147,7 @@ static void SSLerrfree(char *buf);
 #endif
 
 #ifdef USE_SSL
-bool		pq_initssllib = true;
+static bool pq_initssllib = true;
 
 static SSL_CTX *SSL_context = NULL;
 #endif
@@ -212,6 +212,19 @@ KWbuHn491xNO25CQWMtem80uKw+pTnisBRF/454n1Jnhub144YRBoN8CAQI=\n\
 /*			 Procedures common to all secure sessions			*/
 /* ------------------------------------------------------------ */
 
+
+/*
+ * Exported (but as yet undocumented) function to allow application to
+ * tell us it's already initialized OpenSSL.
+ */
+void
+PQinitSSL(int do_init)
+{
+#ifdef USE_SSL
+	pq_initssllib = do_init;
+#endif
+}
+
 /*
  *	Initialize global context
  */
@@ -377,8 +390,10 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 #ifdef ENABLE_THREAD_SAFETY
 	sigset_t	osigmask;
 	bool		sigpipe_pending;
+	bool		got_epipe = false;
 	
-	pq_block_sigpipe(&osigmask, &sigpipe_pending);
+	if (pq_block_sigpipe(&osigmask, &sigpipe_pending) < 0)
+		return -1;
 #else
 #ifndef WIN32
 	pqsigfunc	oldsighandler = pqsignal(SIGPIPE, SIG_IGN);
@@ -413,9 +428,13 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 					char		sebuf[256];
 
 					if (n == -1)
+					{
+						if (SOCK_ERRNO == EPIPE)
+							got_epipe = true;
 						printfPQExpBuffer(&conn->errorMessage,
 								libpq_gettext("SSL SYSCALL error: %s\n"),
 						SOCK_STRERROR(SOCK_ERRNO, sebuf, sizeof(sebuf)));
+					}
 					else
 					{
 						printfPQExpBuffer(&conn->errorMessage,
@@ -448,15 +467,16 @@ pqsecure_write(PGconn *conn, const void *ptr, size_t len)
 	}
 	else
 #endif
+	{
 		n = send(conn->sock, ptr, len, 0);
-		/*
-		 *	Possible optimization:  if sigpending() turns out to be an
-		 *	expensive operation, we can set sigpipe_pending = 'true'
-		 *	here if errno != EPIPE, avoiding a sigpending call.
-		 */
+#ifdef ENABLE_THREAD_SAFETY
+		if (n < 0 && SOCK_ERRNO == EPIPE)
+			got_epipe = true;
+#endif
+	}
 
 #ifdef ENABLE_THREAD_SAFETY
-	pq_reset_sigpipe(&osigmask, sigpipe_pending);
+	pq_reset_sigpipe(&osigmask, sigpipe_pending, got_epipe);
 #else
 #ifndef WIN32
 	pqsignal(SIGPIPE, oldsighandler);
@@ -1228,13 +1248,14 @@ pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending)
 {
 	sigset_t sigpipe_sigset;
 	sigset_t sigset;
-	int		 ret;
 	
 	sigemptyset(&sigpipe_sigset);
 	sigaddset(&sigpipe_sigset, SIGPIPE);
 
 	/* Block SIGPIPE and save previous mask for later reset */
-	ret = pthread_sigmask(SIG_BLOCK, &sigpipe_sigset, osigset);
+	SOCK_ERRNO_SET(pthread_sigmask(SIG_BLOCK, &sigpipe_sigset, osigset));
+	if (SOCK_ERRNO)
+		return -1;
 
 	/* We can have a pending SIGPIPE only if it was blocked before */
 	if (sigismember(osigset, SIGPIPE))
@@ -1251,31 +1272,39 @@ pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending)
 	else
 		*sigpipe_pending = false;
 	
-	return ret;
+	return 0;
 }
 	
 /*
  *	Discard any pending SIGPIPE and reset the signal mask.
- *	We might be discarding a blocked SIGPIPE that we didn't generate,
- *	but we document that you can't keep blocked SIGPIPE calls across
- *	libpq function calls.
+ *
+ * Note: we are effectively assuming here that the C library doesn't queue
+ * up multiple SIGPIPE events.  If it did, then we'd accidentally leave
+ * ours in the queue when an event was already pending and we got another.
+ * As long as it doesn't queue multiple events, we're OK because the caller
+ * can't tell the difference.
+ *
+ * The caller should say got_epipe = FALSE if it is certain that it
+ * didn't get an EPIPE error; in that case we'll skip the clear operation
+ * and things are definitely OK, queuing or no.  If it got one or might have
+ * gotten one, pass got_epipe = TRUE.
+ *
+ * We do not want this to change errno, since if it did that could lose
+ * the error code from a preceding send().  We essentially assume that if
+ * we were able to do pq_block_sigpipe(), this can't fail.
  */
-int
-pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending)
+void
+pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending, bool got_epipe)
 {
+	int	save_errno = SOCK_ERRNO;
 	int	signo;
 	sigset_t sigset;
 
 	/* Clear SIGPIPE only if none was pending */
-	if (!sigpipe_pending)
+	if (got_epipe && !sigpipe_pending)
 	{
-		if (sigpending(&sigset) != 0)
-			return -1;
-	
-		/*
-		 *	Discard pending and blocked SIGPIPE
-		 */
-		if (sigismember(&sigset, SIGPIPE))
+		if (sigpending(&sigset) == 0 &&
+			sigismember(&sigset, SIGPIPE))
 		{
 			sigset_t sigpipe_sigset;
 			
@@ -1283,12 +1312,12 @@ pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending)
 			sigaddset(&sigpipe_sigset, SIGPIPE);
 
 			sigwait(&sigpipe_sigset, &signo);
-			if (signo != SIGPIPE)
-				return -1;
 		}
 	}
 	
 	/* Restore saved block mask */
-	return pthread_sigmask(SIG_SETMASK, osigset, NULL);
+	pthread_sigmask(SIG_SETMASK, osigset, NULL);
+
+	SOCK_ERRNO_SET(save_errno);
 }
 #endif

src/interfaces/libpq/libpq-fe.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.114 2004/12/02 15:32:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.115 2004/12/02 23:20:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -279,6 +279,9 @@ extern SSL *PQgetssl(PGconn *conn);
 extern void *PQgetssl(PGconn *conn);
 #endif
 
+/* Tell libpq whether it needs to initialize OpenSSL */
+extern void PQinitSSL(int do_init);
+
 /* Set verbosity for PQerrorMessage and PQresultErrorMessage */
 extern PGVerbosity PQsetErrorVerbosity(PGconn *conn, PGVerbosity verbosity);
 
@@ -301,11 +304,9 @@ extern PQnoticeProcessor PQsetNoticeProcessor(PGconn *conn,
  *	   Only required for multithreaded apps that use kerberos
  *	   both within their app and for postgresql connections.
  */
-typedef void (pgthreadlock_t) (int acquire);
+typedef void (*pgthreadlock_t) (int acquire);
 
-extern pgthreadlock_t *PQregisterThreadLock(pgthreadlock_t *newhandler);
-
-extern void PQinitSSL(int do_init);
+extern pgthreadlock_t PQregisterThreadLock(pgthreadlock_t newhandler);
 
 /* === in fe-exec.c === */
 
@@ -495,8 +496,6 @@ extern int	PQdsplen(const unsigned char *s, int encoding);
 /* Get encoding id from environment variable PGCLIENTENCODING */
 extern int	PQenv2encoding(void);
 
-/* === in fe-secure.c === */
-
 #ifdef __cplusplus
 }
 #endif

src/interfaces/libpq/libpq-int.h

@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2004, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.97 2004/12/02 15:32:54 momjian Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-int.h,v 1.98 2004/12/02 23:20:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -379,13 +379,13 @@ extern int pqPacketSend(PGconn *conn, char pack_type,
 			 const void *buf, size_t buf_len);
 
 #ifdef ENABLE_THREAD_SAFETY
-extern pgthreadlock_t *g_threadlock;
+extern pgthreadlock_t pg_g_threadlock;
 
-#define pglock_thread() g_threadlock(true);
-#define pgunlock_thread() g_threadlock(false);
+#define pglock_thread()		pg_g_threadlock(true)
+#define pgunlock_thread()	pg_g_threadlock(false)
 #else
-#define pglock_thread() ((void)0)
-#define pgunlock_thread() ((void)0)
+#define pglock_thread()		((void) 0)
+#define pgunlock_thread()	((void) 0)
 #endif
 
 
@@ -476,13 +476,10 @@ extern void pqsecure_close(PGconn *);
 extern ssize_t pqsecure_read(PGconn *, void *ptr, size_t len);
 extern ssize_t pqsecure_write(PGconn *, const void *ptr, size_t len);
 
-#ifdef USE_SSL
-extern bool pq_initssllib;
-#endif
-
 #ifdef ENABLE_THREAD_SAFETY
-int pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending);
-int pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending);
+extern int	pq_block_sigpipe(sigset_t *osigset, bool *sigpipe_pending);
+extern void pq_reset_sigpipe(sigset_t *osigset, bool sigpipe_pending,
+							 bool got_epipe);
 #endif
 
 /*