Re: SymGetTypeInfo and TI_GET_SYMNAME

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From: Oleg Starodumov (oleg_staro_at_hotmail.com)
Date: 03/26/04

  • Next message: Nicolas Hognon: "Re: SymGetTypeInfo and TI_GET_SYMNAME" 
    Date: Fri, 26 Mar 2004 12:03:50 +0200

    Hi,

    > I alredy read the Under The Hood article called "Improved Error
    > Reporting with DBGHELP 5.1 APIs" but I cannot succed to get the name of
    > my parameters type when they are user defined (my own string class, ....).
    >

    Since I remember it was I who suggested you to use this article,
    I must apologize and say that the article is far from enough to complete
    the task. It shows how to work with the simplest types, but nothing more.

    To be able to work with all possible types, it is necessary to become familiar
    with symbol types (identified by "tags") and relationships between symbols.

    Since DbgHelp and DIA work with the same data and use the same concepts,
    DIA documentation can help here:
    http://msdn.microsoft.com/library/en-us/diasdk/html/vsoriDebugInterfaceAccessSDK.asp?frame=true

    > 2. here is my callback function to test SymGetTypeInfo with TI_GET_SYMNAME
    >
    > static BOOL CALLBACK MyEnumSymbolsCallback(PSYMBOL_INFO symbol,
    > ULONG symbolSize,
    > PVOID userContext)
    > {
    > WCHAR* pwszTypeName = 0;
    > if (SymGetTypeInfo(ProcessHandle,
    > symbol->ModBase,
    > symbol->TypeIndex,
    > TI_GET_SYMNAME,
    > &pwszTypeName)) {
    > // ok I've got the name
    > LocalFree(pwszTypeName);
    > } else {
    > // FAILED :(((
    > }
    > }
    >
    > And it always failed :(((
    >

    Failed because "name" property (identified by TI_GET_SYMNAME) is not supported
    for the symbol identified by TypeIndex. It is possible to get the type name only if symbol's
    type is a class, structure, union, enum, typedef. For all other types, name is not available directly
    or at all (basic type - not available, use TI_GET_BASETYPE to get BasicType enumeration
    instead; pointer type - it is necessary to remember that it is a pointer and skip to the type
    the pointer points to; array - no name at all; function type - no name at all).

    So the basic procedure is the following:
    1) Use TI_GET_SYMTAG with SYMBOL_INFO.TypeIndex to obtain the tag of the type symbol.
    2) Depending on the tag, use the type symbol's properties to reconstruct the type declaration
    (not necessarily a name, think of array type as an example).
    3) For some type symbols, it is necessary to analyze some additional symbols (may be children,
    obtained using TI_FINDCHILDREN, may be by an index obtained through a property).

    >
    > and I succed to get the following information
    >
    > TestCurrentFunctionInfo(p0=0x12fa58,
    > char p1="titi",
    > char p2="TITI",
    > char p3=c,
    > int p4=3,
    > int p5=1243756)
    >
    > but i want
    > void TestCurrentFunctionInfo(vkString p0="adresse of str",
    > const char* p1="titi",
    > char* p2="TITI",
    > char p3=c,
    > int p4=3,
    > int* p5="adresse of array")
    >

    The code from the article works only with the simplest types.
    With everything else (such as pointer types) it works incorrectly.

    Regards,
    Oleg

  • Next message: Nicolas Hognon: "Re: SymGetTypeInfo and TI_GET_SYMNAME"