compiler/clib/access.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     POSIX function access().
   6 */
   7
   8 #include <errno.h>
   9 #include <proto/dos.h>
  10 #include <dos/filesystem.h>
  11
  12 #include <aros/debug.h>
  13
  14 #include "__errno.h"
  15 #include "__upath.h"
  16
  17 /*****************************************************************************
  18
  19     NAME */
  20 #include <unistd.h>
  21
  22         int access (
  23
  24 /*  SYNOPSIS */
  25         const char *path,
  26         int         mode)
  27
  28 /*  FUNCTION
  29         Check access permissions of a file or pathname
  30
  31     INPUTS
  32         path - the path of the file being checked
  33         mode - the bitwise inclusive OR of the access permissions
  34                to be checked:
  35
  36                W_OK - for write permission
  37                R_OK - for readpermissions
  38                X_OK - for execute permission
  39                F_OK - Just to see whether the file exists
  40
  41     RESULT
  42         If path cannot be found or if any of the desired access
  43         modes would not be granted, then a -1 value is returned;
  44         otherwise a 0 value is returned.
  45
  46     NOTES
  47         Even if a process has appropriate privileges and indicates
  48         success for X_OK, the file may not actually have execute
  49         permission bits set.  Likewise for R_OK and W_OK.
  50
  51     EXAMPLE
  52
  53     BUGS
  54
  55     SEE ALSO
  56         open(), ftruncate()
  57
  58     INTERNALS
  59
  60 ******************************************************************************/
  61 {
  62     ULONG amode = 0;
  63     BPTR fh;
  64
  65     if (!path) /* safety check */
  66     {
  67         errno = EFAULT;
  68         return -1;
  69     }
  70
  71     /* how can we check whether a file exists without having read permission?? */
  72     if (!mode) mode = R_OK;
  73
  74     if (mode & R_OK) amode |= FMF_READ;
  75     if (mode & W_OK) amode |= FMF_WRITE;
  76     if (mode & X_OK) amode |= FMF_EXECUTE;
  77
  78     if (!(fh = Lock(__path_u2a(path), amode)))
  79     {
  80         errno = IoErr2errno(IoErr());
  81         return -1;
  82     }
  83
  84     Close(fh);
  85     return 0;
  86 }