Use lseek64 and ltell64 to support large object greater than 2gb in size.

psycopg/lobject.h

@@ -60,8 +60,8 @@ RAISES_NEG HIDDEN int lobject_export(lobjectObject *self, const char *filename);
 RAISES_NEG HIDDEN Py_ssize_t lobject_read(lobjectObject *self, char *buf, size_t len);
 RAISES_NEG HIDDEN Py_ssize_t lobject_write(lobjectObject *self, const char *buf,
                                 size_t len);
-RAISES_NEG HIDDEN int lobject_seek(lobjectObject *self, int pos, int whence);
+RAISES_NEG HIDDEN long lobject_seek(lobjectObject *self, long pos, int whence);
-RAISES_NEG HIDDEN int lobject_tell(lobjectObject *self);
+RAISES_NEG HIDDEN long lobject_tell(lobjectObject *self);
 RAISES_NEG HIDDEN int lobject_truncate(lobjectObject *self, size_t len);
 RAISES_NEG HIDDEN int lobject_close(lobjectObject *self);
 

psycopg/lobject_int.c

@@ -376,21 +376,21 @@ lobject_read(lobjectObject *self, char *buf, size_t len)
 
 /* lobject_seek - move the current position in the lo */
 
-RAISES_NEG int
+RAISES_NEG long
-lobject_seek(lobjectObject *self, int pos, int whence)
+lobject_seek(lobjectObject *self, long pos, int whence)
 {
     PGresult *pgres = NULL;
     char *error = NULL;
-    int where;
+    long where;
 
-    Dprintf("lobject_seek: fd = %d, pos = %d, whence = %d",
+    Dprintf("lobject_seek: fd = %d, pos = %Ld, whence = %d",
             self->fd, pos, whence);
 
     Py_BEGIN_ALLOW_THREADS;
     pthread_mutex_lock(&(self->conn->lock));
 
-    where = lo_lseek(self->conn->pgconn, self->fd, pos, whence);
+    where = lo_lseek64(self->conn->pgconn, self->fd, pos, whence);
-    Dprintf("lobject_seek: where = %d", where);
+    Dprintf("lobject_seek: where = %Ld", where);
     if (where < 0)
         collect_error(self->conn, &error);
 
@@ -404,20 +404,20 @@ lobject_seek(lobjectObject *self, int pos, int whence)
 
 /* lobject_tell - tell the current position in the lo */
 
-RAISES_NEG int
+RAISES_NEG long
 lobject_tell(lobjectObject *self)
 {
     PGresult *pgres = NULL;
     char *error = NULL;
-    int where;
+    long where;
 
     Dprintf("lobject_tell: fd = %d", self->fd);
 
     Py_BEGIN_ALLOW_THREADS;
     pthread_mutex_lock(&(self->conn->lock));
 
-    where = lo_tell(self->conn->pgconn, self->fd);
+    where = lo_tell64(self->conn->pgconn, self->fd);
-    Dprintf("lobject_tell: where = %d", where);
+    Dprintf("lobject_tell: where = %Ld", where);
     if (where < 0)
         collect_error(self->conn, &error);
 

psycopg/lobject_type.c

@@ -121,7 +121,7 @@ static PyObject *
 psyco_lobj_read(lobjectObject *self, PyObject *args)
 {
     PyObject *res;
-    int where, end;
+    long where, end;
     Py_ssize_t size = -1;
     char *buffer;
 
@@ -165,10 +165,10 @@ psyco_lobj_read(lobjectObject *self, PyObject *args)
 static PyObject *
 psyco_lobj_seek(lobjectObject *self, PyObject *args)
 {
-    int offset, whence=0;
+    long offset, pos=0;
-    int pos=0;
+    int whence=0;
 
-    if (!PyArg_ParseTuple(args, "i|i", &offset, &whence))
+    if (!PyArg_ParseTuple(args, "l|i", &offset, &whence))
         return NULL;
 
     EXC_IF_LOBJ_CLOSED(self);
@@ -178,7 +178,7 @@ psyco_lobj_seek(lobjectObject *self, PyObject *args)
     if ((pos = lobject_seek(self, offset, whence)) < 0)
         return NULL;
 
-    return PyInt_FromLong((long)pos);
+    return PyLong_FromLong(pos);
 }
 
 /* tell method - tell current position in the lobject */
@@ -189,7 +189,7 @@ psyco_lobj_seek(lobjectObject *self, PyObject *args)
 static PyObject *
 psyco_lobj_tell(lobjectObject *self, PyObject *args)
 {
-    int pos;
+    long pos;
 
     EXC_IF_LOBJ_CLOSED(self);
     EXC_IF_LOBJ_LEVEL0(self);
@@ -198,7 +198,7 @@ psyco_lobj_tell(lobjectObject *self, PyObject *args)
     if ((pos = lobject_tell(self)) < 0)
         return NULL;
 
-    return PyInt_FromLong((long)pos);
+    return PyLong_FromLong(pos);
 }
 
 /* unlink method - unlink (destroy) the lobject */

tests/test_lobject.py

@@ -225,6 +225,24 @@ class LargeObjectTests(LargeObjectTestCase):
         self.assertEqual(lo.seek(-2, 2), length - 2)
         self.assertEqual(lo.read(), "ta")
 
+    def test_seek_tell_greater_than_2gb(self):
+        lo = self.conn.lobject()
+
+        # write chunks until its 3gb
+        length = 0
+        for _ in range(24):
+            # each chunk is written with 128mb
+            length += lo.write("data" * (1 << 25))
+        self.assertEqual(lo.tell(), length)
+        lo.close()
+        lo = self.conn.lobject(lo.oid)
+
+        # seek to 3gb - 4, last written text should be data
+        offset = (1 << 31) + (1 << 30) - 4  # 2gb + 1gb - 4
+        self.assertEqual(lo.seek(offset, 0), offset)
+        self.assertEqual(lo.tell(), offset)
+        self.assertEqual(lo.read(), "data")
+
     def test_unlink(self):
         lo = self.conn.lobject()
         lo.unlink()