library.h

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#ifndef LSST_BASE_LIBRARY_H
#define LSST_BASE_LIBRARY_H
 
#include <stdexcept>
#include <string>
 
#include <dlfcn.h>
#ifndef RTLD_DEEPBIND // Non-POSIX flag, so it may not exist
#define RTLD_DEEPBIND 0 // Will be ignored
#endif
 
namespace lsst {
namespace base {
 
class LibraryException : public std::runtime_error {
public:
    LibraryException(std::string const& name) :
        std::runtime_error("Unable to dynamically load library " + name) {};
    LibraryException(std::string const& lib, std::string const& func) :
        std::runtime_error("Unable to find function " + func + " from dynamically loaded library " + lib) {};
};
 
std::string libraryExtension();
 
std::string getLibraryFilename(std::string const& name);
 
bool canLoadLibrary(
    std::string const& libName          
    );
 
 
template <typename T>
T* loadSymbol(
    std::string const& libName,         
    std::string const& symName          
    )
{
    void* lib = dlopen(getLibraryFilename(libName).c_str(), RTLD_NOW | RTLD_GLOBAL | RTLD_DEEPBIND);
    if (!lib) {
        throw LibraryException(libName);
    }
 
    T* sym;
    (void*&)sym = dlsym(lib, symName.c_str());
    if (!sym) {
        throw LibraryException(libName, symName);
    }
    return sym;
}
 
}} // lsst::base
 
 
#endif