try_signal

The try_signal library provide a way to turn signals into C++ exceptions. This is especially useful when performing disk I/O via memory mapped files, where I/O errors are reported as SIGBUS and SIGSEGV or as structured exceptions on windows.

The function try_signal takes a function object that will be executed once. If the function causes a signal (or structured exception) to be raised, it will throw a C++ exception. Note that RAII may not be relied upon within this function. It may not rely on destructors being called. Stick to simple operations like memcopy.

Example:

#include <stdexcept>
#include <vector>
#include <numeric>
#include "try_signal.hpp"
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>

int main() try
{
        int fd = open("test_file", O_RDWR);
        void* map = mmap(nullptr, 1024, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);

        std::vector<char> buf(1024);
        std::iota(buf.begin(), buf.end(), 0);

        // disk full or access after EOF are reported as exceptions
        sig::try_signal([&]{
                std::memcpy(map, buf.data(), buf.size());
        });

        munmap(map, 1024);
        close(fd);
        return 0;
}
catch (std::exception const& e)
{
        fprintf(stderr, "exited with exception: %s\n", e.what());
        return 1;
}