64 lines
1.7 KiB
NASM
64 lines
1.7 KiB
NASM
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; obj.asm
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;
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; Copyright (C) 1992, MicroSoft Corporation
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;
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; Contains pointer validation routine
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;
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; History: sriniK 02/01/1991 original
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; (8.20.91) v-dougk made into far proc
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;/
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.286p
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.MODEL MEDIUM
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.CODE
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;**************************** _CheckPointer ****************************
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;
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; WORD _CheckPointer (lp, access)
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;
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; Args:
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; lp pointer to be verified
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; access 0 test the pointer for read access
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; 1 test the pointer for write access
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; returns:
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; FALSE invalid pointer
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; TRUE valid pointer
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;
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;
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;
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public _CheckPointer
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_CheckPointer proc
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push bp
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mov bp, sp
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xor ax, ax ; assume an error
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and word ptr [bp+0AH], -1
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jnz check_write_access
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verr word ptr [bp+8] ; check selector for read access
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jnz error
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jmp short check_offset
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check_write_access:
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verw word ptr [bp+8] ; check selector for write access
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jnz error
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check_offset:
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lsl bx, word ptr [bp+8] ; segment limit gets copied into BX
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jnz error
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cmp [bp+6], bx
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ja error
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or ax, -1
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error:
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pop bp
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ret
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_CheckPointer endp
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end
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