RISC DISC 1/RISC_DISC_1.iso/pd_share/code/unixlib/!UnixLib/src/unix/c/getcwd

Text File | 1994-09-30 | 4.6 KB | 285 lines

static char sccs_id[] = "@(#) getcwd.c 3.0 " __DATE__ " HJR";

/*
 * Completely re-written by Alun Jones, [e-mail], 23/2/94,
 * The original version corrupted the P.S.D. when run.
 *
 * OS_Args 7 and Prefix$Dir hacke by [e-mail]
 */

/* getcwd.c (c) Copyright 1990 H.Rogers */

/* thanks to Andy ([e-mail]) for the OS calls */

#include <errno.h>
#include <string.h>
#include <stdlib.h>

#include "sys/unix.h"
#include "sys/os.h"
#include "sys/param.h"
#include "sys/syslib.h"

char *
getcwd (char *v, int l)
{
  char ro_path[MAXPATHLEN];
  char *rp = ro_path + MAXPATHLEN - 1;
  char b[MAXPATHLEN];
  register char *s, *t;
  int r[10];
  os_error *e;
  int handle;

  /* Try OS_Args 7 (get cannonicalised name) */

  /* Open CSD for read only */
  if (!os_fopen (0x40, "@", &handle))
    {
      r[0] = 7;
      r[1] = handle;
      r[2] = (int) ro_path;
      r[5] = MAXPATHLEN;
      e = os_swi (9, r);
      os_fclose (handle);
      if (!e)
    {            /* OS_ARGS 7 worked, parse the path name */
      s = ro_path;
      t = v;
      *t++ = '/';
      l--;
      while (*s && *s != '$' && l-- > 0)
        *t++ = *s++;

      while (*s && l-- > 0)
        {
          if (*s != '.')
        *t++ = *s;
          else
        *t++ = '/';
          s++;
        }
      if (l == 0)
        {
          errno = ENOMEM;
          return 0;
        }
      else
        {
          *t = '\0';
          return v;
        }
    }
    }

  r[0] = (int) "Prefix$Dir";
  r[1] = (int) ro_path;
  r[2] = MAXPATHLEN - 1;
  r[3] = 0;
  r[4] = 0;
  os_swi (0x23, r);
  if (r[2] > 0)
    {
      ro_path[r[2]] = '\0';
      s = ro_path;
      t = v;
      *t++ = '/';
      l--;
      while (*s && *s != '$' && l-- > 0)
    *t++ = *s++;

      while (*s && l-- > 0)
    {
      if (*s != '.')
        *t++ = *s;
      else
        *t++ = '/';
      s++;
    }
      if (l == 0)
    {
      errno = ENOMEM;
      return 0;
    }
      else
    {
      *t = '\0';
      return v;
    }
    }
  /* Search backwards up the tree.
   */
  *rp = 0;
  while (1)
    {
      /* Read current directory name
       */
      r[0] = 6;
      r[2] = (int) b;
      if (e = os_swi (0x0c, r))
    {
      /* Failed to read dirname
       * So swap CSD & PSD then chdir back to original
       * directory.
       */
      __seterr (e);
      if (*rp)
        {
          r[0] = 0;
          r[1] = (int) "\\";
          if (!os_swi (0x29, r))
        {
          /* cd \ successful, so now need to cd \.{rp}
           */
          *--rp = '.';
          *--rp = '\\';
        }
          r[0] = 0;
          r[1] = (int) rp;
          os_swi (0x29, r);
        }
      return 0;
    }

      /* If at root directory then break
       */
      if ((b[2] == '$') && (b[1] == 1))
    {
      break;
    }

      /* Copy the directory name into the RISC OS name
       * buffer.
       */
      rp -= b[1];
      memcpy (rp, b + 2, b[1]);
      *--rp = '.';

      /* Now select PSD.
       */
      r[0] = 0;
      r[1] = (int) "\\";
      if (os_swi (0x29, r))
    {
      /* If cd \ failed then just cd ^
       */
      r[0] = 0;
      r[1] = (int) "^";
      os_swi (0x29, r);
    }
      else
    {
      /* Select new PSD.^
       * This ensures that the PSD doesn't get corrupted by
       * calling getcwd()
       */
      r[0] = 0;
      r[1] = (int) "\\.^";
      os_swi (0x29, r);
    }
    }

  /* OK, reached the root directory.
   */
  *--rp = '$';

  /* Again, PSD then original directory
   */
  r[0] = 0;
  r[1] = (int) "\\";
  if (e = os_swi (0x29, r))
    {
      __seterr (e);
      return 0;
    }

  r[0] = 0;
  r[1] = (int) rp;
  if (e = os_swi (0x29, r))
    {
      __seterr (e);
      return 0;
    }

  /* OK, rp now contains the current directory, and
   * the PSD is unchanged.
   *
   * Next find the FS name.
   */

  /* FS number
   */
  if (e = os_args (0, 0, 0, r))
    {
      __seterr (e);
      return 0;
    }

  /* Convert number to name
   */
  r[1] = r[0];
  r[2] = (int) b + 1;
  r[3] = MAXPATHLEN;
  r[0] = 33;
  if (e = os_swi (0x29, r))
    {
      __seterr (e);
      return (0);
    }

  /* Now have "/ADFS::", for example in b.
   */
  b[0] = '/';
  strcat (b, "::");

  /* Copy the disk name across to v
   */
  if (strlen (b) < l)
    {
      strcpy (v, b);
    }
  else
    {
      errno = ENOMEM;
      return 0;
    }

  /* Next find the disk name
   */
  r[0] = 5;
  r[2] = (int) b;
  if (e = os_swi (0x0c, r))
    {
      __seterr (e);
      return 0;
    }
  *(b + b[0] + 1) = '\0';
  strcat (b, ".$");
  if (strlen (v) + strlen (b + 1) < l)
    {
      strcat (v, b + 1);
    }
  else
    {
      errno = ENOMEM;
      return (0);
    }

  /* v now contains "/ADFS::fred.$", for example.

   * Finally convert the RISC OS name from rp, appending it to v.
   */
  s = v + strlen (v);
  for (t = rp + 1; *t; t++)
    {
      if (s - v == l)
    {
      errno = ENOMEM;
      return 0;
    }
      *s++ = (*t == '.') ? '/' : *t;
    }
  *s = '\0';
  return (v);
}