open.c

linux syslinux source code

#ident "$Id: open.c,v 1.4 2004/11/23 23:43:02 hpa Exp $"
/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 2003-2004 H. Peter Anvin - All Rights Reserved
 *
 *   Permission is hereby granted, free of charge, to any person
 *   obtaining a copy of this software and associated documentation
 *   files (the "Software"), to deal in the Software without
 *   restriction, including without limitation the rights to use,
 *   copy, modify, merge, publish, distribute, sublicense, and/or
 *   sell copies of the Software, and to permit persons to whom
 *   the Software is furnished to do so, subject to the following
 *   conditions:
 *   
 *   The above copyright notice and this permission notice shall
 *   be included in all copies or substantial portions of the Software.
 *   
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 *   OTHER DEALINGS IN THE SOFTWARE.
 *
 * ----------------------------------------------------------------------- */

#include <errno.h>
#include <com32.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include "file.h"

/*
 * open.c
 *
 * Open an ordinary file
 */

extern ssize_t __file_read(struct file_info *, void *, size_t);
extern int __file_close(struct file_info *);

static const struct input_dev file_dev = {
  .dev_magic = __DEV_MAGIC,
  .flags     = __DEV_FILE | __DEV_INPUT,
  .fileflags = O_RDONLY,
  .read      = __file_read,
  .close     = __file_close,
};

int open(const char *pathname, int flags, ...)
{
  com32sys_t regs;
  int fd;
  struct file_info *fp;

  fd = opendev(&file_dev, NULL, flags);

  if ( fd < 0 )
    return -1;
  
  fp = &__file_info[fd];

  strlcpy(__com32.cs_bounce, pathname, __com32.cs_bounce_size);

  regs.eax.w[0] = 0x0006;
  regs.esi.w[0] = OFFS(__com32.cs_bounce);
  regs.es = SEG(__com32.cs_bounce);

  __com32.cs_intcall(0x22, &regs, &regs);
  
  if ( (regs.eflags.l & EFLAGS_CF) || regs.esi.w[0] == 0 ) {
    errno = ENOENT;
    return -1;
  }

  {
    uint16_t blklg2;
    asm("bsrw %1,%0" : "=r" (blklg2) : "rm" (regs.ecx.w[0]));
    fp->i.blocklg2 = blklg2;
  }
  fp->i.length    = regs.eax.l;
  fp->i.filedes   = regs.esi.w[0];
  fp->i.offset    = 0;
  fp->i.nbytes    = 0;

  return fd;
}