don't try deserializing short blobs (#249)

* don't try deserializing short blobs

* use first() instead of only()

Author: aplavin

src/SQLite.jl

@@ -328,6 +328,9 @@ end
 const SERIALIZATION = sqlserialize(0)[1:18]
 
 function sqldeserialize(r)
+    if sizeof(r) < sizeof(SERIALIZATION)
+        return r
+    end
     ret = ccall(:memcmp, Int32, (Ptr{UInt8}, Ptr{UInt8}, UInt),
             SERIALIZATION, r, min(sizeof(SERIALIZATION), sizeof(r)))
     if ret == 0

test/runtests.jl

@@ -458,6 +458,14 @@ end
     SQLite.drop!(db, "bool_data");
 end
 
+@testset "serialization edgecases" begin
+    db = SQLite.DB()
+    r = DBInterface.execute(db, "SELECT zeroblob(2) as b") |> columntable
+    @test first(r.b) == [0, 0]
+    r = DBInterface.execute(db, "SELECT zeroblob(0) as b") |> columntable
+    @test first(r.b) == []
+end
+
 @testset "Stmt scope" begin
     dbfile = joinpath(tempdir(), "test_stmt_scope.sqlite")
     db = SQLite.DB(dbfile)