Fix lo_import and lo_export to return useful error messages more often.

tglsfdc · tglsfdc · commit bc433317ae2b · 2012-10-08T21:52:34.000-04:00
I found that these functions tend to return -1 while leaving an empty error
message string in the PGconn, if they suffer some kind of I/O error on the
file.  The reason is that lo_close, which thinks it's executed a perfectly
fine SQL command, clears the errorMessage.  The minimum-change workaround
is to reorder operations here so that we don't fill the errorMessage until
after lo_close.
diff --git a/src/interfaces/libpq/fe-lobj.c b/src/interfaces/libpq/fe-lobj.c
@@ -168,7 +168,7 @@ lo_truncate(PGconn *conn, int fd, size_t len)
 	if (len > (size_t) INT_MAX)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("argument of lo_truncate exceeds integer range\n"));
+		   libpq_gettext("argument of lo_truncate exceeds integer range\n"));
 		return -1;
 	}
 
@@ -219,7 +219,7 @@ lo_truncate64(PGconn *conn, int fd, pg_int64 len)
 	if (conn->lobjfuncs->fn_lo_truncate64 == 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("cannot determine OID of function lo_truncate64\n"));
+		  libpq_gettext("cannot determine OID of function lo_truncate64\n"));
 		return -1;
 	}
 
@@ -277,7 +277,7 @@ lo_read(PGconn *conn, int fd, char *buf, size_t len)
 	if (len > (size_t) INT_MAX)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("argument of lo_read exceeds integer range\n"));
+			   libpq_gettext("argument of lo_read exceeds integer range\n"));
 		return -1;
 	}
 
@@ -332,7 +332,7 @@ lo_write(PGconn *conn, int fd, const char *buf, size_t len)
 	if (len > (size_t) INT_MAX)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("argument of lo_write exceeds integer range\n"));
+			  libpq_gettext("argument of lo_write exceeds integer range\n"));
 		return -1;
 	}
 
@@ -423,7 +423,7 @@ lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence)
 	if (conn->lobjfuncs->fn_lo_lseek64 == 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("cannot determine OID of function lo_lseek64\n"));
+			 libpq_gettext("cannot determine OID of function lo_lseek64\n"));
 		return -1;
 	}
 
@@ -598,7 +598,7 @@ lo_tell64(PGconn *conn, int fd)
 	if (conn->lobjfuncs->fn_lo_tell64 == 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
-			libpq_gettext("cannot determine OID of function lo_tell64\n"));
+			  libpq_gettext("cannot determine OID of function lo_tell64\n"));
 		return -1;
 	}
 
@@ -753,10 +753,16 @@ lo_import_internal(PGconn *conn, const char *filename, Oid oid)
 
 	if (nbytes < 0)
 	{
+		/* We must do lo_close before setting the errorMessage */
+		int			save_errno = errno;
+
+		(void) lo_close(conn, lobj);
+		(void) close(fd);
 		printfPQExpBuffer(&conn->errorMessage,
 					  libpq_gettext("could not read from file \"%s\": %s\n"),
-						  filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
-		lobjOid = InvalidOid;
+						  filename,
+						  pqStrerror(save_errno, sebuf, sizeof(sebuf)));
+		return InvalidOid;
 	}
 
 	(void) close(fd);
@@ -801,11 +807,15 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
 	 */
 	fd = open(filename, O_CREAT | O_WRONLY | O_TRUNC | PG_BINARY, 0666);
 	if (fd < 0)
-	{							/* error */
+	{
+		/* We must do lo_close before setting the errorMessage */
+		int			save_errno = errno;
+
+		(void) lo_close(conn, lobj);
 		printfPQExpBuffer(&conn->errorMessage,
 						  libpq_gettext("could not open file \"%s\": %s\n"),
-						  filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
-		(void) lo_close(conn, lobj);
+						  filename,
+						  pqStrerror(save_errno, sebuf, sizeof(sebuf)));
 		return -1;
 	}
 
@@ -817,11 +827,15 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
 		tmp = write(fd, buf, nbytes);
 		if (tmp != nbytes)
 		{
-			printfPQExpBuffer(&conn->errorMessage,
-					   libpq_gettext("could not write to file \"%s\": %s\n"),
-						  filename, pqStrerror(errno, sebuf, sizeof(sebuf)));
+			/* We must do lo_close before setting the errorMessage */
+			int			save_errno = errno;
+
 			(void) lo_close(conn, lobj);
 			(void) close(fd);
+			printfPQExpBuffer(&conn->errorMessage,
+					   libpq_gettext("could not write to file \"%s\": %s\n"),
+							  filename,
+							  pqStrerror(save_errno, sebuf, sizeof(sebuf)));
 			return -1;
 		}
 	}
@@ -839,7 +853,8 @@ lo_export(PGconn *conn, Oid lobjId, const char *filename)
 		result = -1;
 	}
 
-	if (close(fd))
+	/* if we already failed, don't overwrite that msg with a close error */
+	if (close(fd) && result >= 0)
 	{
 		printfPQExpBuffer(&conn->errorMessage,
 					   libpq_gettext("could not write to file \"%s\": %s\n"),

Original file line number	Diff line number	Diff line change
`@@ -168,7 +168,7 @@ lo_truncate(PGconn *conn, int fd, size_t len)`
`168`	`168`	`if (len > (size_t) INT_MAX)`
`169`	`169`	`{`
`170`	`170`	`printfPQExpBuffer(&conn->errorMessage,`
`171`		`- libpq_gettext("argument of lo_truncate exceeds integer range\n"));`
	`171`	`+ libpq_gettext("argument of lo_truncate exceeds integer range\n"));`
`172`	`172`	`return -1;`
`173`	`173`	`}`
`174`	`174`
`@@ -219,7 +219,7 @@ lo_truncate64(PGconn *conn, int fd, pg_int64 len)`
`219`	`219`	`if (conn->lobjfuncs->fn_lo_truncate64 == 0)`
`220`	`220`	`{`
`221`	`221`	`printfPQExpBuffer(&conn->errorMessage,`
`222`		`- libpq_gettext("cannot determine OID of function lo_truncate64\n"));`
	`222`	`+ libpq_gettext("cannot determine OID of function lo_truncate64\n"));`
`223`	`223`	`return -1;`
`224`	`224`	`}`
`225`	`225`
`@@ -277,7 +277,7 @@ lo_read(PGconn conn, int fd, char buf, size_t len)`
`277`	`277`	`if (len > (size_t) INT_MAX)`
`278`	`278`	`{`
`279`	`279`	`printfPQExpBuffer(&conn->errorMessage,`
`280`		`- libpq_gettext("argument of lo_read exceeds integer range\n"));`
	`280`	`+ libpq_gettext("argument of lo_read exceeds integer range\n"));`
`281`	`281`	`return -1;`
`282`	`282`	`}`
`283`	`283`
`@@ -332,7 +332,7 @@ lo_write(PGconn conn, int fd, const char buf, size_t len)`
`332`	`332`	`if (len > (size_t) INT_MAX)`
`333`	`333`	`{`
`334`	`334`	`printfPQExpBuffer(&conn->errorMessage,`
`335`		`- libpq_gettext("argument of lo_write exceeds integer range\n"));`
	`335`	`+ libpq_gettext("argument of lo_write exceeds integer range\n"));`
`336`	`336`	`return -1;`
`337`	`337`	`}`
`338`	`338`
`@@ -423,7 +423,7 @@ lo_lseek64(PGconn *conn, int fd, pg_int64 offset, int whence)`
`423`	`423`	`if (conn->lobjfuncs->fn_lo_lseek64 == 0)`
`424`	`424`	`{`
`425`	`425`	`printfPQExpBuffer(&conn->errorMessage,`
`426`		`- libpq_gettext("cannot determine OID of function lo_lseek64\n"));`
	`426`	`+ libpq_gettext("cannot determine OID of function lo_lseek64\n"));`
`427`	`427`	`return -1;`
`428`	`428`	`}`
`429`	`429`
`@@ -598,7 +598,7 @@ lo_tell64(PGconn *conn, int fd)`
`598`	`598`	`if (conn->lobjfuncs->fn_lo_tell64 == 0)`
`599`	`599`	`{`
`600`	`600`	`printfPQExpBuffer(&conn->errorMessage,`
`601`		`- libpq_gettext("cannot determine OID of function lo_tell64\n"));`
	`601`	`+ libpq_gettext("cannot determine OID of function lo_tell64\n"));`
`602`	`602`	`return -1;`
`603`	`603`	`}`
`604`	`604`
`@@ -753,10 +753,16 @@ lo_import_internal(PGconn conn, const char filename, Oid oid)`
`753`	`753`
`754`	`754`	`if (nbytes < 0)`
`755`	`755`	`{`
	`756`	`+ /* We must do lo_close before setting the errorMessage */`
	`757`	`+ int save_errno = errno;`
	`758`	`+`
	`759`	`+ (void) lo_close(conn, lobj);`
	`760`	`+ (void) close(fd);`
`756`	`761`	`printfPQExpBuffer(&conn->errorMessage,`
`757`	`762`	`libpq_gettext("could not read from file \"%s\": %s\n"),`
`758`		`- filename, pqStrerror(errno, sebuf, sizeof(sebuf)));`
`759`		`- lobjOid = InvalidOid;`
	`763`	`+ filename,`
	`764`	`+ pqStrerror(save_errno, sebuf, sizeof(sebuf)));`
	`765`	`+ return InvalidOid;`
`760`	`766`	`}`
`761`	`767`
`762`	`768`	`(void) close(fd);`
`@@ -801,11 +807,15 @@ lo_export(PGconn conn, Oid lobjId, const char filename)`
`801`	`807`	`*/`
`802`	`808`	`fd = open(filename, O_CREAT \| O_WRONLY \| O_TRUNC \| PG_BINARY, 0666);`
`803`	`809`	`if (fd < 0)`
`804`		`- { /* error */`
	`810`	`+ {`
	`811`	`+ /* We must do lo_close before setting the errorMessage */`
	`812`	`+ int save_errno = errno;`
	`813`	`+`
	`814`	`+ (void) lo_close(conn, lobj);`
`805`	`815`	`printfPQExpBuffer(&conn->errorMessage,`
`806`	`816`	`libpq_gettext("could not open file \"%s\": %s\n"),`
`807`		`- filename, pqStrerror(errno, sebuf, sizeof(sebuf)));`
`808`		`- (void) lo_close(conn, lobj);`
	`817`	`+ filename,`
	`818`	`+ pqStrerror(save_errno, sebuf, sizeof(sebuf)));`
`809`	`819`	`return -1;`
`810`	`820`	`}`
`811`	`821`
`@@ -817,11 +827,15 @@ lo_export(PGconn conn, Oid lobjId, const char filename)`
`817`	`827`	`tmp = write(fd, buf, nbytes);`
`818`	`828`	`if (tmp != nbytes)`
`819`	`829`	`{`
`820`		`- printfPQExpBuffer(&conn->errorMessage,`
`821`		`- libpq_gettext("could not write to file \"%s\": %s\n"),`
`822`		`- filename, pqStrerror(errno, sebuf, sizeof(sebuf)));`
	`830`	`+ /* We must do lo_close before setting the errorMessage */`
	`831`	`+ int save_errno = errno;`
	`832`	`+`
`823`	`833`	`(void) lo_close(conn, lobj);`
`824`	`834`	`(void) close(fd);`
	`835`	`+ printfPQExpBuffer(&conn->errorMessage,`
	`836`	`+ libpq_gettext("could not write to file \"%s\": %s\n"),`
	`837`	`+ filename,`
	`838`	`+ pqStrerror(save_errno, sebuf, sizeof(sebuf)));`
`825`	`839`	`return -1;`
`826`	`840`	`}`
`827`	`841`	`}`
`@@ -839,7 +853,8 @@ lo_export(PGconn conn, Oid lobjId, const char filename)`
`839`	`853`	`result = -1;`
`840`	`854`	`}`
`841`	`855`
`842`		`- if (close(fd))`
	`856`	`+ /* if we already failed, don't overwrite that msg with a close error */`
	`857`	`+ if (close(fd) && result >= 0)`
`843`	`858`	`{`
`844`	`859`	`printfPQExpBuffer(&conn->errorMessage,`
`845`	`860`	`libpq_gettext("could not write to file \"%s\": %s\n"),`