Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / io-1.0.19 / fexist.m

diff --git a/octave_packages/io-1.0.19/fexist.m b/octave_packages/io-1.0.19/fexist.m
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+## Copyright (C) 2008 Jaroslav Hajek <highegg@gmail.com>
+##
+## 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 3 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, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn{Function File} ex = fexist (file, tspec, aspec)
+## Checks whether a file exists.
+## @var{file} is the queried file path.
+## @var{tspec} is a combination of letters f,d,p,S, corresponding
+## to file types:
+## @itemize
+## @item f: regular file
+## @item d: directory
+## @item p: named pipe (FIFO special file)
+## @item S: socket
+## @end itemize
+##
+## The query is true if the actual file type matches any of 
+## the specified options.
+##
+## @var{aspec} is a combination of letters r,w,x, corresponding
+## to queried access privileges to the file. The query is true
+## if the current user has all the spefied types of access, either
+## through "user", "group" or "other" specs.
+##
+## @seealso{stat, lstat}
+## @end deftypefn
+
+function ex = fexist (file, tspec, aspec)
+s = stat (file);
+if (isempty (s))
+  ex = 0;
+else
+  ex = 1;
+  if (nargin >= 2 && ! isempty (tspec))
+    ft = 0;
+    for c = tspec
+      switch (c)
+      case 'f'
+       ft |= S_ISREG (s.mode);
+      case 'd'
+       ft |= S_ISDIR (s.mode);
+      case 'p'
+       ft |= S_ISFIFO (s.mode);
+      case 'S'
+       ft |= S_ISSOCK (s.mode);
+      otherwise
+       error ("invalid file type spec: %s", c)
+      endswitch
+    endfor
+    ex &= ft;
+  endif
+  if (ex && nargin >= 3 && ! isempty (aspec))
+    at = 1;
+    mypid = (s.uid == getuid ());
+    mygid = (s.gid == getgid ());
+    mstr = s.modestr(2:end);
+    for c = aspec
+      switch (c)
+      case 'r'
+       at &= (mypid && mstr(1) == c) || (mygid && mstr(4) == c) || mstr(7) == c;
+      case 'w'
+       at &= (mypid && mstr(2) == c) || (mygid && mstr(5) == c) || mstr(8) == c;
+      case 'x'
+       at &= (mypid && mstr(3) == c) || (mygid && mstr(6) == c) || mstr(9) == c;
+      otherwise
+       error ("invalid access type spec: %s", c)
+      endswitch
+    endfor
+    ex &= at;
+  endif
+endif