set_permissions: work natively with older matlab

Author: scivision

+stdlib/set_permissions.m

@@ -2,27 +2,53 @@
 % optional: mex
 %
 %%% Inputs
-% * path {mustBeTextScalar}
-% * readable (1,1) int (-1 remove read permission, 0 no change, 1 add read permission)
-% * writable (1,1) int (-1 remove write permission, 0 no change, 1 add write permission)
-% * executable (1,1) int (-1 remove execute permission, 0 no change, 1 add execute permission)
+% * file
+% * readable   (-1 remove read permission,    0 no change, 1 add read permission)
+% * writable   (-1 remove write permission,   0 no change, 1 add write permission)
+% * executable (-1 remove execute permission, 0 no change, 1 add execute permission)
 %%% Outputs
 % * ok (1,1) logical
 
-function ok = set_permissions(path, readable, writable, executable)
+function ok = set_permissions(file, readable, writable, executable)
 arguments
-  path {mustBeTextScalar,mustBeFile}
+  file {mustBeTextScalar}
   readable (1,1) {mustBeInteger, mustBeInRange(readable, -1, 1)}
   writable (1,1) {mustBeInteger, mustBeInRange(writable, -1, 1)}
   executable (1,1) {mustBeInteger, mustBeInRange(executable, -1, 1)}
 end
 
+ok = false;
+
+if ~stdlib.exists(file), return, end
+
 
 if isMATLABReleaseOlderThan('R2025a')
-  warning("stdlib:set_permissions:RequiresMex", "set_permissions requires 'buildtool mex'");
-  ok = false;
+
+  mode = '';
+  if readable == 1
+    mode = [mode '+r'];
+  elseif readable == -1
+    mode = [mode '-r'];
+  end
+  if writable == 1
+    mode = [mode '+w'];
+  elseif writable == -1
+    mode = [mode '-w'];
+  end
+  if executable == 1
+    mode = [mode '+x'];
+  elseif executable == -1
+    mode = [mode '-x'];
+  end
+
+  [s, msg, id] = fileattrib(file, mode);
+  ok = s == 1;
+  if ~ok
+    warning(id, "Failed to set permissions for %s: %s", file, msg)
+  end
+
 else
-  p = filePermissions(path);
+  p = filePermissions(file);
 
   if readable ~= 0
     setPermissions(p, "Readable", readable > 0);

test/TestPermissions.m

@@ -32,11 +32,10 @@ function test_get_permissions(tc, Ps)
 end
 
 
-function test_set_permissions(tc)
+function test_set_permissions_noread(tc)
 import matlab.unittest.constraints.StartsWithSubstring
 
-tc.assumeTrue(~isMATLABReleaseOlderThan('R2025a') || stdlib.is_mex_fun('stdlib.set_permissions'))
-
+tc.assumeFalse((ispc() && isMATLABReleaseOlderThan('R2025a')) || isMATLABReleaseOlderThan('R2022a'))
 td = tc.createTemporaryFolder();
 
 nr = fullfile(td, "no-read");
@@ -45,18 +44,24 @@ function test_set_permissions(tc)
 tc.verifyTrue(stdlib.set_permissions(nr, -1, 0, 0))
 p = stdlib.get_permissions(nr);
 
-if ~ispc
 tc.verifyThat(p, StartsWithSubstring("-"), "no-read permission failed to set")
 end
 
+
+function test_set_permissions_nowrite(tc)
+import matlab.unittest.constraints.StartsWithSubstring
+
+tc.assumeFalse(isMATLABReleaseOlderThan('R2022a'))
+td = tc.createTemporaryFolder();
+
 nw = fullfile(td, "no-write");
 
 tc.verifyTrue(stdlib.touch(nw))
 tc.verifyTrue(stdlib.set_permissions(nw, 0, -1, 0))
 p = stdlib.get_permissions(nw);
 
-if ~ispc
-tc.verifyThat(p, StartsWithSubstring("r-"), "no-write permission failed to set")
+if ~ispc() || ~isMATLABReleaseOlderThan('R2025a')
+  tc.verifyThat(p, StartsWithSubstring("r-"), "no-write permission failed to set")
 end
 
 end