How do I get the directory that a program is runni

Question

Is there a platform-agnostic and filesystem-agnostic method to obtain the full path of the directory from where a program is running using C/C++? Not to be confused with the current working directory. (Please don't suggest libraries unless they're standard ones like clib or STL.)

(If there's no platform/filesystem-agnostic method, suggestions that work in Windows and Linux for specific filesystems are welcome too.)

Answer 1

You can not use argv[0] for that purpose, usually it does contain full path to the executable, but not nessesarily - process could be created with arbitrary value in the field.

Also mind you, the current directory and the directory with the executable are two different things, so getcwd() won't help you either.

On Windows use GetModuleFileName(), on Linux read /dev/proc/procID/.. files.

Answer 2

This is from the cplusplus forum

On windows:

#include <string>
#include <windows.h>

std::string getexepath()
{
  char result[ MAX_PATH ];
  return std::string( result, GetModuleFileName( NULL, result, MAX_PATH ) );
}

On Linux:

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

std::string getexepath()
{
  char result[ PATH_MAX ];
  ssize_t count = readlink( "/proc/self/exe", result, PATH_MAX );
  return std::string( result, (count > 0) ? count : 0 );
}

On HP-UX:

#include <string>
#include <limits.h>
#define _PSTAT64
#include <sys/pstat.h>
#include <sys/types.h>
#include <unistd.h>

std::string getexepath()
{
  char result[ PATH_MAX ];
  struct pst_status ps;

  if (pstat_getproc( &ps, sizeof( ps ), 0, getpid() ) < 0)
    return std::string();

  if (pstat_getpathname( result, PATH_MAX, &ps.pst_fid_text ) < 0)
    return std::string();

  return std::string( result );
}