PB 4.51 - glGetString - 32-64 bits bug [FALSE ALERT !]

[Guimauve]

Hello everyone,

The following code work fine on Linux Ubuntu 10.10 x86_64 but don't work on Debian Lenny x86_32. We get an "Invalid Memory Access" error when we try to read string from glGetString() function.

Code: Select all

; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
; Project name : glGetString() - 32/64 bits bug
; File Name : glGetString - 32-64 bug.pb
; File version: 1.0.0
; Programmation : OK
; Programmed by : Guimauve
; Date : 05-02-2011
; Mise à jour : 05-02-2011
; PureBasic code : 4.51
; Plateform : Linux (Ubuntu x86_64, Debian Lenny x86)
; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
  
; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
; Bug description :
;
; The bug appear on the Debian Lenny x86 (32 bits) with
; the pointer returned by the glGetString() function. 
;
; We get an "Invalid Memory Access" error message when 
; we try To Read the string With PeekS() function.
; 
; On Linux Ubuntu x86_64 (64 bits) we don't have any
; problems. Everything work as expected. No "Invalid 
; Memory Access" error message, no crash, no program
; freeze, absolutly nothing.
;
; Possible source :
;
; 1. A problem with the glGetString() function Import.
; 2. A problem with the PeekS() function on Linux 32 bits OS.
; 3. A problem with the glGetString() function it's self.
;
; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

#GL_VENDOR                          = $1F00 
#GL_RENDERER                        = $1F01 
#GL_VERSION                         = $1F02 
#GL_EXTENSIONS                      = $1F03 

ImportC "-lGL" 

  glGetString(Name.l) 
  
EndImport
  
ImportC "-lSDL"
  
  SDL_Init(Flag.l)
  SDL_SetVideoMode(Width.l, Height.l, BitsPerPixel.l, Flags.l)
  SDL_Quit()
  
EndImport 
  
NewList GLExtension.s()
  
If SDL_Init(#SDL_INIT_EVERYTHING) = -1
  
  MessageRequester("Fatal Error", "SDL_Init() - Impossible to initialize SDL library.")
  End
  
Else 
  
  ExamineDesktops()
  Width = DesktopWidth(0)
  Height = DesktopHeight(0)
  Depth = DesktopDepth(0)
  SDL_Surface.i = SDL_SetVideoMode(Width, Height, Depth, #SDL_FULLSCREEN|#SDL_OPENGL)
  
  If SDL_Surface = #Null
    
    MessageRequester("Fatal Error", "SDL_SetVideoMode() - Impossible to set the video mode.")
    End 
    
  Else
    
    GL_VENDOR.i = glGetString(#GL_VENDOR)
    GL_VERSION.i = glGetString(#GL_VERSION)
    GL_RENDERER.i = glGetString(#GL_RENDERER)
    GL_EXTENSIONS.i = glGetString(#GL_EXTENSIONS)
    
    If GL_VENDOR > #Null
      VendorName.s = PeekS(GL_VENDOR)
      Debug VendorName
    EndIf 
    
    If GL_VERSION > #Null
      Version.s = PeekS(GL_VERSION)
      Debug Version
    EndIf 
    
    If GL_RENDERER > #Null
      Renderer.s = PeekS(GL_RENDERER)
      Debug Renderer
    EndIf 
    
    If GL_EXTENSIONS > #Null
      
      Extension.s = PeekS(GL_EXTENSIONS)
      Max = CountString(Extension, " ") - 1
      
      For ExtensionID = 0 To Max
        AddElement(GLExtension())
        GLExtension() = StringField(Extension, ExtensionID + 1, " ")
        Debug GLExtension()
      Next
      
    EndIf 
    
    SDL_Quit()
    
  EndIf
   
EndIf 
   
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; <<<<< END OF FILE <<<<<
; <<<<<<<<<<<<<<<<<<<<<<<

On my computer :

NVIDIA Corporation
3.3.0 NVIDIA 260.19.06
GeForce GTX 295/PCI/SSE2
GL_ARB_blend_func_extended
GL_ARB_color_buffer_float
GL_ARB_compatibility
GL_ARB_copy_buffer
GL_ARB_depth_buffer_float
GL_ARB_depth_clamp
GL_ARB_depth_texture
GL_ARB_draw_buffers
GL_ARB_draw_elements_base_vertex
GL_ARB_draw_instanced
GL_ARB_ES2_compatibility
GL_ARB_explicit_attrib_location
GL_ARB_fragment_coord_conventions
GL_ARB_fragment_program
GL_ARB_fragment_program_shadow
GL_ARB_fragment_shader
GL_ARB_framebuffer_object
GL_ARB_framebuffer_sRGB
GL_ARB_geometry_shader4
GL_ARB_get_program_binary
GL_ARB_half_float_pixel
GL_ARB_half_float_vertex
GL_ARB_imaging
GL_ARB_instanced_arrays
GL_ARB_map_buffer_range
GL_ARB_multisample
GL_ARB_multitexture
GL_ARB_occlusion_query
GL_ARB_occlusion_query2
GL_ARB_pixel_buffer_object
GL_ARB_point_parameters
GL_ARB_point_sprite
GL_ARB_provoking_vertex
GL_ARB_robustness
GL_ARB_sampler_objects
GL_ARB_seamless_cube_map
GL_ARB_separate_shader_objects
GL_ARB_shader_bit_encoding
GL_ARB_shader_objects
GL_ARB_shading_language_100
GL_ARB_shadow
GL_ARB_sync
GL_ARB_texture_border_clamp
GL_ARB_texture_buffer_object
GL_ARB_texture_compression
GL_ARB_texture_compression_rgtc
GL_ARB_texture_cube_map
GL_ARB_texture_env_add
GL_ARB_texture_env_combine
GL_ARB_texture_env_crossbar
GL_ARB_texture_env_dot3
GL_ARB_texture_float
GL_ARB_texture_mirrored_repeat
GL_ARB_texture_multisample
GL_ARB_texture_non_power_of_two
GL_ARB_texture_rectangle
GL_ARB_texture_rg
GL_ARB_texture_rgb10_a2ui
GL_ARB_texture_swizzle
GL_ARB_timer_query
GL_ARB_transform_feedback2
GL_ARB_transpose_matrix
GL_ARB_uniform_buffer_object
GL_ARB_vertex_array_bgra
GL_ARB_vertex_array_object
GL_ARB_vertex_buffer_object
GL_ARB_vertex_program
GL_ARB_vertex_shader
GL_ARB_vertex_type_2_10_10_10_rev
GL_ARB_viewport_array
GL_ARB_window_pos
GL_ATI_draw_buffers
GL_ATI_texture_float
GL_ATI_texture_mirror_once
GL_S3_s3tc
GL_EXT_texture_env_add
GL_EXT_abgr
GL_EXT_bgra
GL_EXT_bindable_uniform
GL_EXT_blend_color
GL_EXT_blend_equation_separate
GL_EXT_blend_func_separate
GL_EXT_blend_minmax
GL_EXT_blend_subtract
GL_EXT_compiled_vertex_array
GL_EXT_Cg_shader
GL_EXT_depth_bounds_test
GL_EXT_direct_state_access
GL_EXT_draw_buffers2
GL_EXT_draw_instanced
GL_EXT_draw_range_elements
GL_EXT_fog_coord
GL_EXT_framebuffer_blit
GL_EXT_framebuffer_multisample
GL_EXTX_framebuffer_mixed_formats
GL_EXT_framebuffer_object
GL_EXT_framebuffer_sRGB
GL_EXT_geometry_shader4
GL_EXT_gpu_program_parameters
GL_EXT_gpu_shader4
GL_EXT_multi_draw_arrays
GL_EXT_packed_depth_stencil
GL_EXT_packed_float
GL_EXT_packed_pixels
GL_EXT_pixel_buffer_object
GL_EXT_point_parameters
GL_EXT_provoking_vertex
GL_EXT_rescale_normal
GL_EXT_secondary_color
GL_EXT_separate_shader_objects
GL_EXT_separate_specular_color
GL_EXT_shadow_funcs
GL_EXT_stencil_two_side
GL_EXT_stencil_wrap
GL_EXT_texture3D
GL_EXT_texture_array
GL_EXT_texture_buffer_object
GL_EXT_texture_compression_latc
GL_EXT_texture_compression_rgtc
GL_EXT_texture_compression_s3tc
GL_EXT_texture_cube_map
GL_EXT_texture_edge_clamp
GL_EXT_texture_env_combine
GL_EXT_texture_env_dot3
GL_EXT_texture_filter_anisotropic
GL_EXT_texture_integer
GL_EXT_texture_lod
GL_EXT_texture_lod_bias
GL_EXT_texture_mirror_clamp
GL_EXT_texture_object
GL_EXT_texture_shared_exponent
GL_EXT_texture_sRGB
GL_EXT_texture_swizzle
GL_EXT_timer_query
GL_EXT_transform_feedback2
GL_EXT_vertex_array
GL_EXT_vertex_array_bgra
GL_IBM_rasterpos_clip
GL_IBM_texture_mirrored_repeat
GL_KTX_buffer_region
GL_NV_blend_square
GL_NV_conditional_render
GL_NV_copy_depth_to_color
GL_NV_copy_image
GL_NV_depth_buffer_float
GL_NV_depth_clamp
GL_NV_explicit_multisample
GL_NV_fence
GL_NV_float_buffer
GL_NV_fog_distance
GL_NV_fragment_program
GL_NV_fragment_program_option
GL_NV_fragment_program2
GL_NV_framebuffer_multisample_coverage
GL_NV_geometry_shader4
GL_NV_gpu_program4
GL_NV_half_float
GL_NV_light_max_exponent
GL_NV_multisample_coverage
GL_NV_multisample_filter_hint
GL_NV_occlusion_query
GL_NV_packed_depth_stencil
GL_NV_parameter_buffer_object
GL_NV_parameter_buffer_object2
GL_NV_pixel_data_range
GL_NV_point_sprite
GL_NV_primitive_restart
GL_NV_register_combiners
GL_NV_register_combiners2
GL_NV_shader_buffer_load
GL_NV_texgen_reflection
GL_NV_texture_barrier
GL_NV_texture_compression_vtc
GL_NV_texture_env_combine4
GL_NV_texture_expand_normal
GL_NV_texture_multisample
GL_NV_texture_rectangle
GL_NV_texture_shader
GL_NV_texture_shader2
GL_NV_texture_shader3
GL_NV_transform_feedback
GL_NV_transform_feedback2
GL_NV_vdpau_interop
GL_NV_vertex_array_range
GL_NV_vertex_array_range2
GL_NV_vertex_buffer_unified_memory
GL_NV_vertex_program
GL_NV_vertex_program1_1
GL_NV_vertex_program2
GL_NV_vertex_program2_option
GL_NV_vertex_program3
GL_NVX_conditional_render
GL_NVX_gpu_memory_info
GL_SGIS_generate_mipmap
GL_SGIS_texture_lod
GL_SGIX_depth_texture
GL_SGIX_shadow
GL_SUN_slice_accum

Best regards.
Guimauve

[remi_meier]

Works fine on Ubuntu 10.10 32bit.
You sure you did not enable Unicode on the 32bit system
by chance? Your code is not Unicode-safe. But even so
I do not get a crash when Unicode is enabled...

[Guimauve]

Works fine on Ubuntu 10.10 32bit.
You sure you did not enable Unicode on the 32bit system
by chance? Your code is not Unicode-safe. But even so
I do not get a crash when Unicode is enabled...

As I said, I did not perform the 32bit system test my self. I have just send a little piece of code to Flaith and he reported back to me that my code crash on the PeekS() function just after the glGetString() function call. I have spend many hour to find what is going on but no success. After many try of code working on my computer but not on the Flaith one's, he run a test with Linux mint x64 on a virtual machine and after that my code seem to work without any problems. From this point of view the problems seems to be related to the 32 bit OS. But your observation are just in perfect contradiction of what happen to Flaith when he try my code.

For your question, no at this time I don't compile in Unicode mode because I have an Graphic issue for displaying texture bitmap font on screen. Anyway this an other version working with and without Unicode activated.

Code: Select all

; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
; Project name : glGetString() - 32/64 bits bug
; File Name : glGetString - 32-64 bug.pb
; File version: 1.0.0
; Programmation : OK
; Programmed by : Guimauve
; Date : 05-02-2011
; Mise à jour : 06-02-2011
; PureBasic cade : 4.51
; Plateform : Linux (Ubuntu x86_64, Debian Lenny x86)
; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
; Bug description :
;
; The bug appear on the Debian Lenny x86 (32 bits) with
; the pointer returned by the glGetString() function. 
; (I don't know if this is an issue or not)
;
; We get an "Invalid Memory Access" error message when 
; we try To Read the string With PeekS() function.
; 
; On Linux Ubuntu x86_64 (64 bits) we don't have any
; problems. Everything work as expected. No "Invalid 
; Memory Access" error message, no crash, no program
; freeze, absolutly nothing.
;
; Possible source :
;
; 1. A problem with the glGetString() function Import.
; 2. A problem with the PeekS() function on Linux 32 bits OS.
; 3. A problem with the glGetString() function it's self.
;
; <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

#GL_VENDOR                          = $1F00 
#GL_RENDERER                        = $1F01 
#GL_VERSION                         = $1F02 
#GL_EXTENSIONS                      = $1F03 

ImportC "-lGL" 

  glGetString(Name.l) 
  
EndImport

ImportC "-lSDL"

  SDL_Init(Flag.l)
  SDL_SetVideoMode(Width.l, Height.l, BitsPerPixel.l, Flags.l)
  SDL_Quit()
  
EndImport 

Procedure.s GL_GetString(Name.l)
  
  *Source.Ascii = glGetString(Name)
  
  Char01.a = PeekA(*Source)
  
  While Char01 <> 0

    GL_String.s = GL_String + Chr(Char01)
    *Source + SizeOf(Ascii)
    Char01 = PeekA(*Source)
    
  Wend

  ProcedureReturn GL_String
EndProcedure 

NewList GLExtension.s()

If SDL_Init(#SDL_INIT_EVERYTHING) = -1
  
  MessageRequester("Fatal Error", "SDL_Init() - Impossible to initialize SDL library.")
  End
  
Else 
  
  ExamineDesktops()
  Width = 400
  Height = 300
  Depth = DesktopDepth(0)
  SDL_Surface.i = SDL_SetVideoMode(Width, Height, Depth, #SDL_OPENGL)
  
  If SDL_Surface = #Null
    
    MessageRequester("Fatal Error", "SDL_SetVideoMode() - Impossible to set the video mode.")
    End 
    
  Else
    
    Debug GL_GetString(#GL_VENDOR)
    Debug GL_GetString(#GL_VERSION)
    Debug GL_GetString(#GL_RENDERER)
    
    Extension.s = GL_GetString(#GL_EXTENSIONS)
    Max = CountString(Extension, " ") - 1
    
    For ExtensionID = 0 To Max
      AddElement(GLExtension())
      GLExtension() = StringField(Extension, ExtensionID + 1, " ")
      Debug GLExtension()
    Next
    
    
    SDL_Quit()
    
  EndIf
  
  
EndIf 

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; <<<<< END OF FILE <<<<<
; <<<<<<<<<<<<<<<<<<<<<<<

Best regards
Guimauve

[remi_meier]

Jep, still works.
BUT: Enabling the Purifier crashes the _second_ Example
you posted (Line 69). But I think I remember about some
other purifier bug with strings in procedures. So it may
already be reported somewhere. Or not.

Btw. your GL_GetString() function can be replaced by a
PeekS() with a #PB_Ascii-Flag.

Of course it could also be a driver bug. I'm running the
open source ATI Gallium driver. My output is:

Code: Select all

X.Org R300 Project
2.1 Mesa 7.11-devel
Gallium 0.4 on ATI RV515
GL_ARB_copy_buffer
GL_ARB_depth_texture
GL_ARB_draw_buffers
GL_ARB_draw_elements_base_vertex
GL_ARB_explicit_attrib_location
GL_ARB_fragment_coord_conventions
GL_ARB_fragment_program
GL_ARB_fragment_program_shadow
GL_ARB_fragment_shader
GL_ARB_framebuffer_object
GL_ARB_half_float_pixel
GL_ARB_half_float_vertex
GL_ARB_map_buffer_range
GL_ARB_multisample
GL_ARB_multitexture
GL_ARB_occlusion_query2
GL_ARB_occlusion_query
GL_ARB_pixel_buffer_object
GL_ARB_point_parameters
GL_ARB_point_sprite
GL_ARB_provoking_vertex
GL_ARB_shader_objects
GL_ARB_shading_language_100
GL_ARB_shadow
GL_ARB_texture_border_clamp
GL_ARB_texture_compression
GL_ARB_texture_cube_map
GL_ARB_texture_env_add
GL_ARB_texture_env_combine
GL_ARB_texture_env_crossbar
GL_ARB_texture_env_dot3
GL_ARB_texture_mirrored_repeat
GL_ARB_texture_non_power_of_two
GL_ARB_texture_rectangle
GL_ARB_texture_rg
GL_ARB_texture_swizzle
GL_ARB_transpose_matrix
GL_ARB_vertex_array_bgra
GL_ARB_vertex_array_object
GL_ARB_vertex_buffer_object
GL_ARB_vertex_program
GL_ARB_vertex_shader
GL_ARB_window_pos
GL_EXT_abgr
GL_EXT_bgra
GL_EXT_blend_color
GL_EXT_blend_equation_separate
GL_EXT_blend_func_separate
GL_EXT_blend_logic_op
GL_EXT_blend_minmax
GL_EXT_blend_subtract
GL_EXT_compiled_vertex_array
GL_EXT_copy_texture
GL_EXT_draw_range_elements
GL_EXT_fog_coord
GL_EXT_framebuffer_blit
GL_EXT_framebuffer_multisample
GL_EXT_framebuffer_object
GL_EXT_gpu_program_parameters
GL_EXT_multi_draw_arrays
GL_EXT_packed_depth_stencil
GL_EXT_packed_pixels
GL_EXT_pixel_buffer_object
GL_EXT_point_parameters
GL_EXT_polygon_offset
GL_EXT_provoking_vertex
GL_EXT_rescale_normal
GL_EXT_secondary_color
GL_EXT_separate_shader_objects
GL_EXT_separate_specular_color
GL_EXT_shadow_funcs
GL_EXT_stencil_two_side
GL_EXT_stencil_wrap
GL_EXT_subtexture
GL_EXT_texture3D
GL_EXT_texture_compression_dxt1
GL_EXT_texture_compression_s3tc
GL_EXT_texture_cube_map
GL_EXT_texture_edge_clamp
GL_EXT_texture_env_add
GL_EXT_texture_env_combine
GL_EXT_texture_env_dot3
GL_EXT_texture_filter_anisotropic
GL_EXT_texture_lod_bias
GL_EXT_texture_mirror_clamp
GL_EXT_texture_object
GL_EXT_texture
GL_EXT_texture_rectangle
GL_EXT_texture_sRGB
GL_EXT_texture_sRGB_decode
GL_EXT_texture_swizzle
GL_EXT_vertex_array_bgra
GL_EXT_vertex_array
GL_OES_EGL_image
GL_OES_read_format
GL_APPLE_packed_pixels
GL_APPLE_vertex_array_object
GL_ATI_blend_equation_separate
GL_ATI_separate_stencil
GL_ATI_texture_env_combine3
GL_ATI_texture_mirror_once
GL_IBM_multimode_draw_arrays
GL_IBM_rasterpos_clip
GL_IBM_texture_mirrored_repeat
GL_INGR_blend_func_separate
GL_MESA_pack_invert
GL_MESA_window_pos
GL_MESA_ycbcr_texture
GL_NV_blend_square
GL_NV_conditional_render
GL_NV_light_max_exponent
GL_NV_packed_depth_stencil
GL_NV_texgen_reflection
GL_NV_texture_env_combine4
GL_NV_texture_rectangle
GL_S3_s3tc
GL_SGIS_generate_mipmap
GL_SGIS_texture_border_clamp
GL_SGIS_texture_edge_clamp
GL_SGIS_texture_lod
GL_SUN_multi_draw_arrays

[Guimauve]

Jep, still works.
BUT: Enabling the Purifier crashes the _second_ Example
you posted (Line 69). But I think I remember about some
other purifier bug with strings in procedures. So it may
already be reported somewhere. Or not.

Btw. your GL_GetString() function can be replaced by a
PeekS() with a #PB_Ascii-Flag.

Of course it could also be a driver bug. I'm running the
open source ATI Gallium driver.

I don't understand why this bug just disappear. Flaith just re-run my original code without any problems. What exactly happen, we will probably never know. About my previous code it's one of the test version I have made during my investigation. (I have suspected that one of the possible problem is with the PeekS() function. So I have create an alternative solution to avoid the use of the PeekS() function but still working whatever the compiling mode Ascii or Unicode.)

About about an API internal bug, it's also possible. Anyway everything seems to work fine now so I think we can move on something else.

Btw, a tiny Macro to replace in the previous code.

Code: Select all

Macro GL_GetString(Name)
  
  PeekS(glGetString(Name), -1, #PB_Ascii)
  
EndMacro

Best Regards.
Guimauve