[QPID-4553] C++ qpid::types::Variant::uint8_t not treated as integer during string conversion

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.21
• Fix Version/s: 0.21
• Component/s: C++ Broker

Environment

Linux/windows broker/client Messaging

• Assignee: Unassigned
• Reporter: Charles E. Rolke
• Created: 29/Jan/13 16:10
• Updated: 06/Sep/16 16:35
• Resolved: 12/Feb/13 21:59

Description

There are unexpected conversion side effects when a uint8_t is created from a string. I expected the string value to be decoded into a binary value 0..255, the same as I expect for uint16_t, uint32_t, and uint64_t and their expected values. Instead uint8_t receives the first character of a one-character string as if there's an implicit string-to-single-character conversion. This behavior is not a regression.

Am I mistaken expecting a 0..255 value from the .asUint8() function?

The underlying cause is Boost being invoked through a template that works one way for three of the four cases and a different way for the uint8_t case. I'd like to get rid of that and replace it with a single, common string decode into a 64-bit integer. Then for the smaller subtypes mask the value down to the size of the respective type and throw if there's a range error.

Here's a test where I'm looking at the recent "-0" conversion fix. In all cases I expect the value to be a binary zero. In the uint8_t case it is not. The only case where the conversion does not throw returns a value of 48 '0'.

void testZeroValueAs(const Variant theValue)
{
    std::string phase;
    try
    {
        phase = "64bit - ";
        uint64_t myu64 = theValue.asUint64();
        if (myu64 != 0) 
            std::cout << "Failed at uint64 : "  
                      << myu64 << std::endl;

        phase = "32bit - ";
        uint32_t myu32 = theValue.asUint32();
        if (myu32 != 0) 
            std::cout << "Failed at uint32 : "  
                      << myu32 << std::endl;

        phase = "16bit - ";
        uint16_t myu16 = theValue.asUint16();
        if (myu16 != 0) 
            std::cout << "Failed at uint16 : "  
                      << myu16 << std::endl;

        phase = "8bit - ";
        uint8_t myu8 = theValue.asUint8();
        if (myu8 != 0) 
            std::cout << "Failed at uint8 : " 
                      << myu8 << std::endl;

    } catch (const std::exception& error) {
        std::cout << "Exception in phase " 
                  << phase 
                  << error.what() 
                  << std::endl;
    }
}


    Variant value;
    value = "0";
    testZeroValueAs(value);
    value = "00";
    testZeroValueAs(value);
    value = "-00";
    testZeroValueAs(value);

at run time this example produces:

Failed at uint8 : 0
Exception in phase 8bit - invalid conversion: Cannot convert 00 (..\..\qpid\cpp\src\qpid\types\Variant.cpp:126)
Exception in phase 8bit - invalid conversion: Cannot convert -00 (..\..\qpid\cpp\src\qpid\types\Variant.cpp:126)