Translating the following from windows:

--- C Code:

#define IMAGE_SIZEOF_SHORT_NAME              8

typedef struct _IMAGE_SECTION_HEADER {
    BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
    union {
            DWORD   PhysicalAddress;
            DWORD   VirtualSize;
    } Misc;
    DWORD   VirtualAddress;
    DWORD   SizeOfRawData;
    DWORD   PointerToRawData;
    DWORD   PointerToRelocations;
    DWORD   PointerToLinenumbers;
    WORD    NumberOfRelocations;
    WORD    NumberOfLinenumbers;
    DWORD   Characteristics;
} IMAGE_SECTION_HEADER, *PIMAGE_SECTION_HEADER;

#define IMAGE_SIZEOF_SECTION_HEADER          40

--- D Code:

const uint IMAGE_SIZEOF_SHORT_NAME = 8;
const uint IMAGE_SIZEOF_SECTION_HEADER = 40;

align struct ImageSectionHeader
{
    BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
    union Misc
	{
            DWORD   PhysicalAddress;
            DWORD   VirtualSize;
    }
    DWORD   VirtualAddress;
    DWORD   SizeOfRawData;
    DWORD   PointerToRawData;
    DWORD   PointerToRelocations;
    DWORD   PointerToLinenumbers;
    WORD    NumberOfRelocations;
    WORD    NumberOfLinenumbers;
    DWORD   Characteristics;
}
alias ImageSectionHeader IMAGE_SECTION_HEADER;
alias ImageSectionHeader *PIMAGE_SECTION_HEADER;

the problem is that ImageSectionHeader.sizeof == 36
Any ideas as to why?

akcom wrote:
> Translating the following from windows:
> 
> --- C Code:
> 
> #define IMAGE_SIZEOF_SHORT_NAME              8
> 
> typedef struct _IMAGE_SECTION_HEADER {
>     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
>     union {
>             DWORD   PhysicalAddress;
>             DWORD   VirtualSize;
>     } Misc;
>     DWORD   VirtualAddress;
>     DWORD   SizeOfRawData;
>     DWORD   PointerToRawData;
>     DWORD   PointerToRelocations;
>     DWORD   PointerToLinenumbers;
>     WORD    NumberOfRelocations;
>     WORD    NumberOfLinenumbers;
>     DWORD   Characteristics;
> } IMAGE_SECTION_HEADER, *PIMAGE_SECTION_HEADER;
> 
> #define IMAGE_SIZEOF_SECTION_HEADER          40
> 
> --- D Code:
> 
> const uint IMAGE_SIZEOF_SHORT_NAME = 8;
> const uint IMAGE_SIZEOF_SECTION_HEADER = 40;
> 
> align struct ImageSectionHeader
> {
>     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
>     union Misc
>     {
>             DWORD   PhysicalAddress;
>             DWORD   VirtualSize;
>     }
>     DWORD   VirtualAddress;
>     DWORD   SizeOfRawData;
>     DWORD   PointerToRawData;
>     DWORD   PointerToRelocations;
>     DWORD   PointerToLinenumbers;
>     WORD    NumberOfRelocations;
>     WORD    NumberOfLinenumbers;
>     DWORD   Characteristics;
> }
> alias ImageSectionHeader IMAGE_SECTION_HEADER;
> alias ImageSectionHeader *PIMAGE_SECTION_HEADER;
> 
> the problem is that ImageSectionHeader.sizeof == 36
> Any ideas as to why?

edit:
it appears as if when the union is replaced by a single DWORD, everything works as expected.  Should this be filed as a bug?

On Wed, 31 May 2006 20:31:42 -0400, akcom <CppCoder@gmail.com> wrote:
> akcom wrote:
>> Translating the following from windows:
>>  --- C Code:
>>  #define IMAGE_SIZEOF_SHORT_NAME              8
>>  typedef struct _IMAGE_SECTION_HEADER {
>>     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
>>     union {
>>             DWORD   PhysicalAddress;
>>             DWORD   VirtualSize;
>>     } Misc;
>>     DWORD   VirtualAddress;
>>     DWORD   SizeOfRawData;
>>     DWORD   PointerToRawData;
>>     DWORD   PointerToRelocations;
>>     DWORD   PointerToLinenumbers;
>>     WORD    NumberOfRelocations;
>>     WORD    NumberOfLinenumbers;
>>     DWORD   Characteristics;
>> } IMAGE_SECTION_HEADER, *PIMAGE_SECTION_HEADER;
>>  #define IMAGE_SIZEOF_SECTION_HEADER          40
>>  --- D Code:
>>  const uint IMAGE_SIZEOF_SHORT_NAME = 8;
>> const uint IMAGE_SIZEOF_SECTION_HEADER = 40;
>>  align struct ImageSectionHeader
>> {
>>     BYTE    Name[IMAGE_SIZEOF_SHORT_NAME];
>>     union Misc
>>     {
>>             DWORD   PhysicalAddress;
>>             DWORD   VirtualSize;
>>     }
>>     DWORD   VirtualAddress;
>>     DWORD   SizeOfRawData;
>>     DWORD   PointerToRawData;
>>     DWORD   PointerToRelocations;
>>     DWORD   PointerToLinenumbers;
>>     WORD    NumberOfRelocations;
>>     WORD    NumberOfLinenumbers;
>>     DWORD   Characteristics;
>> }
>> alias ImageSectionHeader IMAGE_SECTION_HEADER;
>> alias ImageSectionHeader *PIMAGE_SECTION_HEADER;
>>  the problem is that ImageSectionHeader.sizeof == 36
>> Any ideas as to why?
>
> edit:
> it appears as if when the union is replaced by a single DWORD, everything works as expected.  Should this be filed as a bug?

No. The D struct you give above declares a type called "Misc" which is a union containing 2 DWORDS, but, you don't actually declare a struct member of that type. In short, your struct does not contain the union at all, only it's type declaration.

You have 2 options:

struct ImageSectionHeader
{
  ..
  union {
    DWORD   PhysicalAddress;
    DWORD   VirtualSize;
  }
  ..
}

this is an anonymous union, of 2 DWORDS, or:

struct ImageSectionHeader
{
  ..
  union NAMED_BOB {  //creates type called NAMED_BOB
    DWORD   PhysicalAddress;
    DWORD   VirtualSize;
  }
  NAMED_BOB Misc;    //includes a NAMED_BOB in the struct, called 'Misc'
  ..
}

both of these give a sizeof 40 for me.

Regan