Category: Programming

I recently ran the gold linker under Thread Sanitizer. It’s a nice plugin for Valgrind which looks for race conditions in multi-threaded programs. To describe it briefly, it builds Happens-Before relationships based on mutex operations and warns when it notices a write and a read/write to the same memory location without a Happens-Before relationship. This…

All Go code lives in a package. Every Go source file starts with a package declaration which names the package that it lives in. A package name is a simple identifier; besides appearing in a package clause, package names are also used when referring to names imported from another package. That poses the problem of…

Now for something really controversial: what’s wrong with protected symbols? In an ELF shared library, an ordinary global symbol may be overridden if a symbol of the same name is defined in the executable or in a shared library which appears earlier in the runtime search path. This is called symbol interposition. It is often…

I recently spent some time sorting through linker version script issues, so I’m going to document what I discovered. Linker symbol versioning was invented at Sun. The Solaris linker lets you use a version script when you create a shared library. This script assigns versions to specific named symbols, and defines a version hierarchy. When…

I recently encountered a nice example of cargo cult programming. In bug 10980 Robert Wohlrab helpfully built a large number of Debian packages with the gold linker and reported errors about unknown options. These were options supported by the GNU linker but not by gold. (I’ve now added all the options to gold). Among the…