symlink: system fallback as these are important functions

Author: scivision

+stdlib/create_symlink.m

@@ -29,25 +29,45 @@
       if stdlib.has_python()
         ok = py_create_symlink(target, link);
       elseif stdlib.dotnet_api() >= 6
-        % https://learn.microsoft.com/en-us/dotnet/api/system.io.file.createsymboliclink
-        try
-          System.IO.File.CreateSymbolicLink(link, target);
-          ok = true;
-        catch e
-          warning(e.identifier, "%s", e.message)
-        end
+        ok = dotnet_create_symlink(target, link);
       else
-        warning(e.identifier, "%s", e.message)
+        ok = system_create_symlink(target, link);
       end
-    case "Octave:undefined-function"
-      err = symlink(target, link);
-      ok = err == 0;
+    case "Octave:undefined-function", ok = symlink(target, link) == 0;
     otherwise, warning(e.identifier, "%s", e.message)
   end
 end
 
 end
 
+
+function ok = system_create_symlink(target, link)
+
+if ispc
+  cmd = sprintf('pwsh -c "New-Item -ItemType SymbolicLink -Path "%s" -Target "%s""', link, target);
+else
+  cmd = sprintf('ln -s "%s" "%s"', target, link);
+end
+
+% suppress output text on powershell
+[stat, ~] = system(cmd);
+
+ok = stat == 0;
+end
+
+
+function ok = dotnet_create_symlink(target, link)
+
+% https://learn.microsoft.com/en-us/dotnet/api/system.io.file.createsymboliclink
+try
+  System.IO.File.CreateSymbolicLink(link, target);
+  ok = true;
+catch e
+  warning(e.identifier, "%s", e.message)
+end
+
+end
+
 %!assert (create_symlink("https://invalid", "https://invalid"), false)
 %!test
 %! if !ispc

+stdlib/is_symlink.m

@@ -16,8 +16,11 @@
         ok = java.nio.file.Files.isSymbolicLink(javaPathObject(stdlib.absolute(p)));
       elseif stdlib.has_python()
         ok = py_is_symlink(p);
-      else
-        ok = logical.empty;
+      elseif isunix()
+        ok = system(sprintf('test -L %s', p)) == 0;
+      elseif ispc()
+        [s, m] = system(sprintf('pwsh -command "(Get-Item -Path %s).Attributes"', p));
+        ok = s == 0 && contains(m, 'ReparsePoint');
       end
     case "Octave:undefined-function"
       % use lstat() to work with a broken symlink, like Matlab isSymbolicLink

+stdlib/read_symlink.m

@@ -19,16 +19,22 @@
     case "MATLAB:UndefinedFunction"
       if ~stdlib.is_symlink(p), return, end
 
-      if stdlib.has_python()
-        r = py_read_symlink(p);
-      elseif stdlib.dotnet_api() >= 6
+      if stdlib.dotnet_api() >= 6
         r = System.IO.FileInfo(p).LinkTarget;
       elseif stdlib.has_java()
         % must be absolute path
         % must not be .canonical or symlink is gobbled!
         r = stdlib.absolute(p);
         % https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/nio/file/Files.html#readSymbolicLink(java.nio.file.Path)
         r = java.nio.file.Files.readSymbolicLink(javaPathObject(r)).string;
+      elseif stdlib.has_python()
+        r = py_read_symlink(p);
+      elseif isunix()
+        [s, m] = system(sprintf('readlink -fn %s', p));
+        if s == 0, r = string(m); end
+      elseif ispc()
+        [s, m] = system(sprintf('pwsh -command "(Get-Item -Path %s).Target"', p));
+        if s == 0, r = string(strip(m)); end
       end
     otherwise, rethrow(e)
   end

buildfile.m

@@ -13,9 +13,6 @@
 
 
 cnomex = ~HasTag("exe") & ~HasTag("mex") & ~HasTag("java");
-if isMATLABReleaseOlderThan("R2024b")
-  cnomex = cnomex & ~HasTag("symlink");
-end
 if ispc()
   cnomex = cnomex & ~HasTag("unix");
 end