How to implement readlink to find the path

This Use the readlink() function properly for the correct uses of the readlink function.

If you have your path in a std::string, you could do something like this:

#include <unistd.h>
#include <limits.h>

std::string do_readlink(std::string const& path) {
    char buff[PATH_MAX];
    ssize_t len = ::readlink(path.c_str(), buff, sizeof(buff)-1);
    if (len != -1) {
      buff[len] = '\0';
      return std::string(buff);
    }
    /* handle error condition */
}

If you’re only after a fixed path:

std::string get_selfpath() {
    char buff[PATH_MAX];
    ssize_t len = ::readlink("/proc/self/exe", buff, sizeof(buff)-1);
    if (len != -1) {
      buff[len] = '\0';
      return std::string(buff);
    }
    /* handle error condition */
}

To use it:

int main()
{
  std::string selfpath = get_selfpath();
  std::cout << selfpath << std::endl;
  return 0;
}