Raise an exception if the libpq fails to decode bytea in hex format

NEWS

@@ -13,6 +13,8 @@ What's new in psycopg 2.4
     time from the backend.
   - The named cursors name can be an invalid identifier.
   - 'cursor.description' is provided in named tuples if available.
+  - Raise a clean exception instead of returning bad data when receiving bytea
+    in 'hex' format and the client libpq can't parse them.
   - Connections and cursors are weakly referenceable.
   - Added 'b' and 't' mode to large objects: write can deal with both bytes
     strings and unicode; read can return either bytes strings or decoded

doc/src/usage.rst

@@ -291,6 +291,9 @@ the SQL string that would be sent to the database.
      configuration or in the client session using a query such as ``SET
      bytea_output TO escape;`` before trying to receive binary data.
      
+     Starting from Psycopg 2.4 this condition is detected and signaled with a
+     `~psycopg2.InterfaceError`.
+
      .. __: http://www.postgresql.org/docs/9.0/static/datatype-binary.html
      .. __: http://www.postgresql.org/docs/9.0/static/runtime-config-client.html#GUC-BYTEA-OUTPUT
 

psycopg/typecast_binary.c

@@ -166,6 +166,19 @@ typecast_BINARY_cast(const char *s, Py_ssize_t l, PyObject *curs)
       goto fail;
     }
 
+    /* Check the escaping was successful */
+    if (s[0] == '\\' && s[1] == 'x'     /* input encoded in hex format */
+        && str[0] == 'x'                /* output resulted in an 'x' */
+        && s[2] != '7' && s[3] != '8')  /* input wasn't really an x (0x78) */
+    {
+        PyErr_SetString(InterfaceError,
+            "can't receive bytea data from server >= 9.0 with the current "
+            "libpq client library: please update the libpq to at least 9.0 "
+            "or set bytea_output to 'escape' in the server config "
+            "or with a query");
+        goto fail;
+    }
+
     chunk = (chunkObject *) PyObject_New(chunkObject, &chunkType);
     if (chunk == NULL) goto fail;
 

tests/test_quote.py

@@ -83,6 +83,10 @@ class QuotingTestCase(unittest.TestCase):
         else:
             res = curs.fetchone()[0].tobytes()
 
+        if res[0] in (b('x'), ord(b('x'))) and self.conn.server_version >= 90000:
+            return self.skipTest(
+                "bytea broken with server >= 9.0, libpq < 9")
+
         self.assertEqual(res, data)
         self.assert_(not self.conn.notices)
 

tests/testutils.py

@@ -140,6 +140,24 @@ def skip_if_no_namedtuple(f):
     return skip_if_no_namedtuple_
 
 
+def skip_if_broken_hex_binary(f):
+    """Decorator to detect libpq < 9.0 unable to parse bytea in hex format"""
+    def cope_with_hex_binary_(self):
+        from psycopg2 import InterfaceError
+        try:
+            return f(self)
+        except InterfaceError, e:
+            if '9.0' in str(e) and self.conn.server_version >= 90000:
+                return self.skipTest(
+                    # FIXME: we are only assuming the libpq is older here,
+                    # but we don't have a reliable way to detect the libpq
+                    # version, not pre-9 at least.
+                    "bytea broken with server >= 9.0, libpq < 9")
+            else:
+                raise
+
+    return cope_with_hex_binary_
+
 def skip_if_no_iobase(f):
     """Skip a test if io.TextIOBase is not available."""
     def skip_if_no_iobase_(self):

tests/types_basic.py

@@ -28,7 +28,7 @@ except:
     pass
 import sys
 import testutils
-from testutils import unittest
+from testutils import unittest, skip_if_broken_hex_binary
 from testconfig import dsn
 
 import psycopg2
@@ -116,6 +116,7 @@ class TypesBasicTests(unittest.TestCase):
         s = self.execute("SELECT %s AS foo", (float("-inf"),))
         self.failUnless(str(s) == "-inf", "wrong float quoting: " + str(s))      
 
+    @skip_if_broken_hex_binary
     def testBinary(self):
         if sys.version_info[0] < 3:
             s = ''.join([chr(x) for x in range(256)])
@@ -142,6 +143,7 @@ class TypesBasicTests(unittest.TestCase):
             b = psycopg2.Binary(bytes([]))
             self.assertEqual(str(b), "''::bytea")
 
+    @skip_if_broken_hex_binary
     def testBinaryRoundTrip(self):
         # test to make sure buffers returned by psycopg2 are
         # understood by execute:
@@ -189,6 +191,7 @@ class TypesBasicTests(unittest.TestCase):
         s = self.execute("SELECT '{}'::text AS foo")
         self.failUnlessEqual(s, "{}")
 
+    @skip_if_broken_hex_binary
     @testutils.skip_from_python(3)
     def testTypeRoundtripBuffer(self):
         o1 = buffer("".join(map(chr, range(256))))
@@ -199,14 +202,18 @@ class TypesBasicTests(unittest.TestCase):
         o1 = buffer("")
         o2 = self.execute("select %s;", (o1,))
         self.assertEqual(type(o1), type(o2))
+        self.assertEqual(str(o1), str(o2))
 
+    @skip_if_broken_hex_binary
     @testutils.skip_from_python(3)
     def testTypeRoundtripBufferArray(self):
         o1 = buffer("".join(map(chr, range(256))))
         o1 = [o1]
         o2 = self.execute("select %s;", (o1,))
         self.assertEqual(type(o1[0]), type(o2[0]))
+        self.assertEqual(str(o1[0]), str(o2[0]))
 
+    @skip_if_broken_hex_binary
     @testutils.skip_before_python(3)
     def testTypeRoundtripBytes(self):
         o1 = bytes(range(256))
@@ -218,6 +225,7 @@ class TypesBasicTests(unittest.TestCase):
         o2 = self.execute("select %s;", (o1,))
         self.assertEqual(memoryview, type(o2))
 
+    @skip_if_broken_hex_binary
     @testutils.skip_before_python(3)
     def testTypeRoundtripBytesArray(self):
         o1 = bytes(range(256))
@@ -225,23 +233,32 @@ class TypesBasicTests(unittest.TestCase):
         o2 = self.execute("select %s;", (o1,))
         self.assertEqual(memoryview, type(o2[0]))
 
+    @skip_if_broken_hex_binary
     @testutils.skip_before_python(2, 6)
     def testAdaptBytearray(self):
         o1 = bytearray(range(256))
         o2 = self.execute("select %s;", (o1,))
+
         if sys.version_info[0] < 3:
             self.assertEqual(buffer, type(o2))
         else:
             self.assertEqual(memoryview, type(o2))
 
+        self.assertEqual(len(o1), len(o2))
+        for c1, c2 in zip(o1, o2):
+            self.assertEqual(c1, ord(c2))
+
         # Test with an empty buffer
         o1 = bytearray([])
         o2 = self.execute("select %s;", (o1,))
+
+        self.assertEqual(len(o2), 0)
         if sys.version_info[0] < 3:
             self.assertEqual(buffer, type(o2))
         else:
             self.assertEqual(memoryview, type(o2))
 
+    @skip_if_broken_hex_binary
     @testutils.skip_before_python(2, 7)
     def testAdaptMemoryview(self):
         o1 = memoryview(bytearray(range(256)))
@@ -259,6 +276,13 @@ class TypesBasicTests(unittest.TestCase):
         else:
             self.assertEqual(memoryview, type(o2))
 
+    def testByteaHexCheckFalsePositive(self):
+        # the check \x -> x to detect bad bytea decode
+        # may be fooled if the first char is really an 'x'
+        o1 = psycopg2.Binary(b('x'))
+        o2 = self.execute("SELECT %s::bytea AS foo", (o1,))
+        self.assertEqual(b('x'), o2[0])
+
 
 class AdaptSubclassTest(unittest.TestCase):
     def test_adapt_subtype(self):