klibc/__shared_init.c

/*
 * __shared_init.c
 *
 * This function takes the raw data block set up by the ELF loader
 * in the kernel and parses it.  It is invoked by crt0.S which makes
 * any necessary adjustments and passes calls this function using
 * the standard C calling convention.
 *
 * The arguments are:
 *  uintptr_t *elfdata	 -- The ELF loader data block; usually from the stack.
 *                          Basically a pointer to argc.
 *  void (*onexit)(void) -- Function to install into onexit
 */

#include <stddef.h>
#include <stdlib.h>
#include <stdint.h>
#include <klibc/compiler.h>
#include <elf.h>

char **environ;

__noreturn __libc_init(uintptr_t *elfdata, void (*onexit)(void))
{
  int argc;
  char **argv, **envp, **envend;
  struct auxentry {
    uintptr_t type;
    uintptr_t v;
  } *auxentry;
  typedef int (*main_t)(int, char **, char **);
  main_t main_ptr = NULL;

  (void)onexit;			/* For now, we ignore this... */

  argc = (int)*elfdata++;
  argv = (char **)elfdata;
  envp = argv+(argc+1);

  /* The auxillary entry vector is after all the environment vars */
  for ( envend = envp ; *envend ; envend++ );
  auxentry = (struct auxentry *)(envend+1);

  while ( auxentry->type ) {
    if ( auxentry->type == AT_ENTRY ) {
      main_ptr = (main_t)(auxentry->v);
      break;
    }
    auxentry++;
  }

  environ = envp;
  exit(main_ptr(argc, argv, envp));
}