FIX: L1126 Link Error May Be Caused By EXPORT in PROC Definition (72849)

SYMPTOMS

When creating an exported function with the Microsoft Macro Assembler (MASM) version 6.0, 6.0a, or 6.0b, the EXPORT keyword can be used in a procedure definition and MASM will automatically generate the correct .OBJ record to add it to the export table for the .EXE (or DLL). This is useful when creating a procedure in a DLL that is called from outside the DLL, when creating a callback procedure in an .EXE, or when defining a procedure as residing in an IOPL segment with OS/2.

However, there is a problem when the EXPORT keyword is used in the latter case. When creating an IOPL function, you must declare the number of words that will be required to hold the parameters for the function. The operating system then uses this value to build the stack that the IOPL function will run on. You normally do this by adding the word count after the function name in the EXPORT section of the associated .DEF file. For example, the .DEF file may contain the following:

   EXPORTS _Func 3

CAUSE

The problem results when you then use the EXPORT keyword in MASM for the procedure definition for the IOPL function as follows:

   Func PROC EXPORT, arg1:WORD, arg2:WORD, arg3:WORD

MASM will generate an EXPDEF (EXPort DEFinition) record that lists the parameter word count as zero. If you then link with the .DEF file that correctly lists the word count as three, the linker will return the following error message:

fatal error L1126: conflicting pwords value

STATUS

Microsoft has confirmed this to be a problem in MASM versions 6.0, 6.0a, and 6.0b. This problem was corrected in MASM for MS-DOS version 6.1.

Sample Code

TEST.ASM

;; Assemble options needed: none

.MODEL large
.286

.CODE
Func PROC C EXPORT, arg1:PTR DWORD, arg2:WORD
Func ENDP
END Func

TEST.DEF

; Module definition file for linking

NAME Test

EXPORTS
   _Func 3