Subversion Repositories openrisc

/* open for MMIXware.

   Copyright (C) 2001, 2002 Hans-Peter Nilsson

   Permission to use, copy, modify, and distribute this software is

   freely granted, provided that the above copyright notice, this notice

   and the following disclaimer are preserved with no changes.

   THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR

   IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED

   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

   PURPOSE.  */

#include <stdlib.h>

#include <fcntl.h>

#include <_ansi.h>

#include <sys/types.h>

#include <sys/stat.h>

#include "sys/syscall.h"

#include <errno.h>

/* Let's keep the filehandle array here, since this is a primary

   initializer of it.  */

unsigned char _MMIX_allocated_filehandle[32] =

 {

   1,

   1,

   1,

   0, 0, 0, 0, 0,

   0, 0, 0, 0, 0, 0, 0, 0,

   0, 0, 0, 0, 0, 0, 0, 0,

   0, 0, 0, 0, 0, 0, 0, 0

 };

int

_open (const char *path,

       int flags, ...)

{

  long fileno;

  unsigned char mode;

  long append_contents = 0;

  unsigned long prev_contents_size = 0;

  char *prev_contents = NULL;

  long ret;

  for (fileno = 0;

       fileno < (sizeof (_MMIX_allocated_filehandle) /

                 sizeof (_MMIX_allocated_filehandle[0]));

       fileno++)

    if (_MMIX_allocated_filehandle[fileno] == 0)

      break;

  if (fileno == (sizeof (_MMIX_allocated_filehandle) /

                 sizeof (_MMIX_allocated_filehandle[0])))

    {

      errno = EMFILE;

      return -1;

    }

  /* We map this to a fopen call.  The flags parameter is stymied because

     we don't support other than these flags.  */

  if (flags & ~(O_RDONLY | O_WRONLY | O_RDWR | O_CREAT | O_APPEND | O_TRUNC))

    {

      UNIMPLEMENTED (("path: %s, flags: %d", path, flags));

      errno = ENOSYS;

      return -1;

    }

  if ((flags & O_ACCMODE) == O_RDONLY)

    mode = BinaryRead;

  else if ((flags & (O_WRONLY | O_APPEND)) == (O_WRONLY | O_APPEND))

    {

      mode = BinaryReadWrite;

      append_contents = 1;

    }

  else if ((flags & (O_RDWR | O_APPEND)) == (O_RDWR | O_APPEND))

    {

      mode = BinaryReadWrite;

      append_contents = 1;

    }

  else if ((flags & (O_WRONLY | O_CREAT)) == (O_WRONLY | O_CREAT)

           || (flags & (O_WRONLY | O_TRUNC)) == (O_WRONLY | O_TRUNC))

    mode = BinaryWrite;

  else if ((flags & (O_RDWR | O_CREAT)) == (O_RDWR | O_CREAT))

    mode = BinaryReadWrite;

  else if (flags & O_RDWR)

    mode = BinaryReadWrite;

  else

    {

      errno = EINVAL;

      return -1;

    }

  if (append_contents)

    {

      /* BinaryReadWrite is equal to "w+", so it truncates the file rather

         than keeping the contents, as can be imagined if you're looking

         for append functionality.  The only way we can keep the contents

         so we can append to it, is by first reading in and saving the

         contents, then re-opening the file as BinaryReadWrite and write

         the previous contents.  This seems to work for the needs of

         simple test-programs.  */

      long openexist = TRAP3f (SYS_Fopen, fileno, path, BinaryRead);

      if (openexist == 0)

        {

          /* Yes, this file exists, now opened, so let's read it and keep

             the contents.  Better have the memory around for this to

             work.  */

          long seekval = TRAP2f (SYS_Fseek, fileno, -1);

          if (seekval == 0)

            {

              prev_contents_size = TRAP1f (SYS_Ftell, fileno);

              /* If the file has non-zero size, we have something to

                 append to.  */

              if (prev_contents_size != 0)

                {

                  /* Start reading from the beginning.  Ignore the return

                     value from this call: we'll notice if we can't read

                     as much as we want.  */

                  TRAP2f (SYS_Fseek, fileno, 0);

                  prev_contents = malloc (prev_contents_size);

                  if (prev_contents != 0)

                    {

                      /* I don't like the thought of trying to read the

                         whole file all at once, disregarding the size,

                         because the host system might not support that

                         and we'd get funky errors.  Read in 32k at a

                         time.  */

                      char *ptr = prev_contents;

                      unsigned long read_more = prev_contents_size;

                      unsigned long chunk_size = 1 << 15;

                      while (read_more >= chunk_size)

                        {

                          long readval

                            = TRAP3f (SYS_Fread, fileno, ptr, chunk_size);

                          if (readval != 0)

                            {

                              free (prev_contents);

                              TRAP1f (SYS_Fclose, fileno);

                              errno = EIO;

                              return -1;

                            }

                          read_more -= chunk_size;

                          ptr += chunk_size;

                        }

                      if (read_more != 0)

                        {

                          long readval

                            = TRAP3f (SYS_Fread, fileno, ptr, read_more);

                          if (readval != 0)

                            {

                              free (prev_contents);

                              TRAP1f (SYS_Fclose, fileno);

                              errno = EIO;

                              return -1;

                            }

                        }

                    }

                  else

                    {

                      /* Malloc of area to copy to failed.  The glibc

                         manpage says its open can return ENOMEM due to

                         kernel memory failures, so let's do that too

                         here.  */

                      errno = ENOMEM;

                      return -1;

                    }

                }

            }

          else

            {

              /* Seek failed.  Gotta be some I/O error.  */

              errno = EIO;

              return -1;

            }

          TRAP1f (SYS_Fclose, fileno);

        }

    }

  ret = TRAP3f (SYS_Fopen, fileno, path, mode);

  if (ret < 0)

    {

      /* It's totally unknown what the error was.  We'll just take our

         chances and assume ENOENT.  */

      errno = ENOENT;

      return -1;

    }

  if (prev_contents_size != 0)

    {

      /* Write out the previous contents, a chunk at a time.  Leave the

         file pointer at the end of the file.  */

      unsigned long write_more = prev_contents_size;

      unsigned long chunk_size = 1 << 15;

      char *ptr = prev_contents;

      while (write_more >= chunk_size)

        {

          long writeval

            = TRAP3f (SYS_Fwrite, fileno, ptr, chunk_size);

          if (writeval != 0)

            {

              free (prev_contents);

              TRAP1f (SYS_Fclose, fileno);

              errno = EIO;

              return -1;

            }

          write_more -= chunk_size;

          ptr += chunk_size;

        }

      if (write_more != 0)

        {

          long writeval

            = TRAP3f (SYS_Fwrite, fileno, ptr, write_more);

          if (writeval != 0)

            {

              free (prev_contents);

              TRAP1f (SYS_Fclose, fileno);

              errno = EIO;

              return -1;

            }

        }

      free (prev_contents);

    }

  _MMIX_allocated_filehandle[fileno] = 1;

  return fileno;

}