[Gambas-user] Issues when writing and reading structures

[Brian G]

Thank you Ben, for the all the work you have done for Structure support, they all work great!

I have been trying to encapsulate the structures within a gambas class. 
I have run into an issue with the serialization using the _read/_write interface.

When doing a  "write myclass as TestElevationClass"
and the class itself just does a "write value as elevation" <-- the actual structure

then the serialization process always adds a 4F as the leading byte of any output stream.
While this works well when reading and writing using the gambas serialization. 
The recieving app not being gambas based goes all crazy.

Is this needed or is there a work around?

See the following script:

-------------------------------------------------------------------------------------

#!/usr/bin/env gbs3
' Gambas Script File Created 03/25/2023 10:38:24

class TestElevationClass

Public Struct elevation
  a As Short
  b As Long
  c As Float
  d As Short
  e As String
End Struct

Public Value As Elevation

Property Read text As String


Public Sub _new()

  value = New Elevation
  value.a = 45
  value.b = 98765
  value.c = 67.465
  value.d = 1
  value.e = "hello Value ............................."

End

Public Sub _write(outfile As File)

  Write #outfile, value As Elevation

End

Public Sub _read(infile As File)

  value = Read #infile As Elevation

End

Private Function text_Read() As String

  Return Subst("&1\t&2\t&3\t&4\t&5", Value.a, Value.b, Value.c, Value.d, Value.e)

End

end class

' Gambas module file

Public Struct elevation
  a As Short
  b As Long
  c As Float
  d As Short
  e As String
End Struct

Public Sub main()

  Dim ee As New TestElevationClass
  Dim b, d As Object
  Dim a As New Elevation
  Dim aa As Elevation
  Dim aaa As Elevation
  
  Dim p As Pointer = Alloc(20000, 1)
  Dim pp As Pointer = Alloc(10000, 1)
  Dim ptr As Pointer = 0

  b = Object.Class(a)

  a.a = 45
  a.b = 98765
  a.c = 67.456
  a.d = 1
  a.e = "hello a.........."

  aa = pp
  aa.a = 45
  aa.b = 98765
  aa.c = 67.465
  aa.d = 1
  aa.e = "hello aa........"

  Dim f As File
  f = Memory p For Write
  Write #f, a As Elevation
  Close #f

  f = Memory p For Read
  aaa = Read #f As Elevation

  For i As Integer = 0 To 50
    Print Hex(Byte@(p + i), 2);;
  Next
  Print

  For i As Integer = 0 To 50
    Print Hex(Byte@(pp + i), 2);;
  Next
  Print

  Print a.a, a.b, a.c, a.d, a.e
  Print aaa.a, aaa.b, aaa.c, aaa.d, aaa.e

  f = Memory p For Write
  Write #f, ee As TestElevationClass
  Close #f

  For i As Integer = 0 To 50
    Print Hex(Byte@(p + i), 2);;
  Next
  Print

  f = Memory p For Read
  ee = Read #f As TestElevationClass
  Print ee.Text

  Free(p)
  Free(pp)

End

---------------------------------------------------------------


"Failure is the key to success; 
 each mistake teaches us something"  .. Morihei Ueshiba
Brian G

----- On Mar 22, 2023, at 7:01 PM, Brian G brian at westwoodsvcs.com wrote:

> I can confirn that on openSUSE 15.4 it also segfaults.
> 
> In more detail on the platforms where it segfaults, it only happens when writing
> structure and only when writing the entire structure. Any single field within
> the structure works fine.
> Reading an entire structure also works fine.
> 
> And the issue seems to be on debian and openSUSE not on Ubuntu/mint systems
> 
> I will investigate a little farther
> 
> "Failure is the key to success;
> each mistake teaches us something"  .. Morihei Ueshiba
> Brian G
> 
> ----- On Mar 22, 2023, at 11:10 AM, Brian G brian at westwoodsvcs.com wrote:
> 
>> I can confirm that it is issue on Debian even with latest version of gambas
>> built on the platform
>> 
>> Will rebuild and test with OpenSUSE now
>> 
>> "Failure is the key to success;
>> each mistake teaches us something"  .. Morihei Ueshiba
>> Brian G
>> 
>> ----- On Mar 22, 2023, at 10:52 AM, T Lee Davidson t.lee.davidson at gmail.com
>> wrote:
>> 
>>> On 3/22/23 11:47, Brian G wrote:
>>>> Which os are you running it on?
>>>> 
>>>> "Failure is the key to success;
>>>>   each mistake teaches us something"  .. Morihei Ueshiba
>>>> Brian G
>>> 
>>> [System]
>>> Gambas=3.18.1
>>> OperatingSystem=Linux
>>> Distribution=openSUSE Leap 15.4
>>> Kernel=5.14.21-150400.24.49-default
>>> Architecture=x86_64
>>> Cores=6
>>> Memory=15921M
>>> Language=en_US.UTF-8
>>> Desktop=KDE
>>> 
>>> 
>>> --
>>> Lee
>>> 
>>> 
>>> ----[ http://gambaswiki.org/wiki/doc/netiquette ]----
>> 
>> ----[ http://gambaswiki.org/wiki/doc/netiquette ]----
> 
> ----[ http://gambaswiki.org/wiki/doc/netiquette ]----