/* Copyright (C) 2005 David Decotigny
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
    
    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 
 #include <crt.h>
 #include <libc.h>
 #include <stdarg.h>
 #include <debug.h>
 
 /**
  * @file myprog14.c
  *
  * uaccess tests. Demonstrate that a page fault in kernel during
  * userspace access (with uaccess.c functions) is NEVER (or at least
  * should not be) fatal:
  *  - licit page faults are resolved as usual (COW, page_in, ...)
  *  - illicit page faults are caught and the uaccess functions tolerate
  *    and report it
  *
  * We use the temporary syscall 4012 (hexdump) to force the kernel to
  * call user_memcpy and do some page faults.
  */
 
 int main()
 {
   char * zoup;
   int fd;
 
   fd = open("/dev/zero", O_RDWR);
   zoup = mmap(0, 8192,
               PROT_READ | PROT_WRITE,
               MAP_SHARED,
               fd, 34);
   close(fd);
 
   bochs_printf("mapped @%x\n", (unsigned)zoup);
 
   /* Do some forks to complicate things */
   fork();
   fork();
 
   /* Force the first page of the mapping to be allocated */
   *zoup = 'a';
 
   _sos_syscall2(4012, (unsigned)zoup, 16384);
   /*
    * all 3 cases are handled here:
    *  - [zoup, zoup + 4kB[: no page fault at all (page already mapped)
    *  - [zoup+4kB, zoup + 8kB[: page fault => /dev/zero page_in() called
    *  - [zoup+8kB, ...[: page fault => illegal user address =>
    *    user_memcpy reports that only 8kB out of the 16kB could be
    *    hexdumped
    */
 
   return 0;
 }