Pointer Problem

[Jodi999]

I have the following:

UINT16 ARCFOUR_Sbox[256];
VPTR ptr;

ptr = &ARCFOUR_Sbox[64];

and I get the errors:
C2109: subscript requires array or pointer type
C2102: '&' requires l-value

Does anyone know what is wrong with 'ptr = &ARCFOUR_Sbox[64];'?

 

[Salem]

Can you post a complete program containing just the relevant declarations, which we can all compile.

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[Jodi999]

Unfortunately, I am working on a classified system and cannot post the program. I had to slightly modify the code as it is.

 

[Salem]

You can't rename and post half a dozen lines?

int main ( ) {
    UINT16 ARCFOUR_Sbox[256];
    VPTR ptr;
    ptr = &ARCFOUR_Sbox[64];
    return 0;
}

Add UINT16 and VPTR declarations so that it breaks your compiler, then post what you find here.
Oh, and don't forget to mention which compiler, unless that's also a secret.

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[Jodi999]

Using Visual C++. Don't have compiler on unclassified network, so I don't know what you'll be missing if you try to compile.

Main.h code:

extern UINT16 ARCFOUR_Sbox;

typedef struct arcfour_state {
UINT16 ij;
UINT16 reserved;
UINT16 salt[10];
Pointer32 part0;
Pointer32 part1;
} PACKED_STRUCTURE_ATTRIBUTE_2 arcfour_state;


typedef struct arcfour_cntxt {
UINT16 config;
kcr key;
UINT16 dp_parts01;
UINT16 endian_parts01;
UINT16 dp_state;
UINT16 endian_state;
Pointer32 state;
} PACKED_STRUCTURE_ATTRIBUTE_2 arcfour_cntxt;


typedef union Pointer32 {
VPTR ptr;
ADDRESS addr;
BYTE ptr8[4];
UINT16 word16[2];
} PACKED_STRUCTURE_ATTRIBUTE_2 Pointer32;



Main.c code:

UINT16 ARCFOUR_Sbox;


void arcfour_init(void)
{
ARCFOUR_KeyId = 9999;
ARCFOUR_Dir = 0;
memset16(ARCFOUR_state, 0, 132);
ARCFOUR_Sbox = &ARCFOUR_state[4];

ARCFOUR_cntxt.state.ptr = &ARCFOUR_intstate.ij;

((arcfour_state *)(ARCFOUR_cntxt.state.ptr))->part0.ptr = ARCFOUR_Sbox;
((arcfour_state *)(ARCFOUR_cntxt.state.ptr))->part1.ptr = &ARCFOUR_Sbox[64]; /*This line gives error*/
}

 

[Salem]

First thing I suggest you do is turn up the warning level on your compiler to maximum, because there seems to be an awful lot of implicit casting going on.

> UINT16 ARCFOUR_Sbox;
This I'm guessing is an integal type, say something like
typedef unsigned short int UINT16;

> ARCFOUR_Sbox = &ARCFOUR_state[4];
This results in an IMPLICIT conversion of a pointer to a struct, to an unsigned short int

> ((arcfour_state *)(ARCFOUR_cntxt.state.ptr))->part0.ptr = ARCFOUR_Sbox;
This results in an IMPLICIT conversion of an unsigned short int to a pointer.
I'm guessing
typedef void * pointer32;

> &ARCFOUR_Sbox[64]; /*This line gives error*/
Yeah, ARCFOUR_Sbox is of an integral type, so its no surprise that you can't subscript it.

Well you could change the declaration to this
UINT16 *ARCFOUR_Sbox;
which would fix the immediately apparent problems with the code you posted, but I rather suspect there are wider issues at stake.

Like for instance, having done this
> &ARCFOUR_Sbox[64];
do you know that part1.ptr is 128 bytes past part0.ptr?

In your first post, you said
> UINT16 ARCFOUR_Sbox[256];
So what gives?
Posting accurate information really helps you know.

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