Handle permission denied error at nu_engine::glob_from (#14679)

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#14528 mentioned that trying to `open` a file in a directory where you
don't have read access results in a "file not found" error. I
investigated the error and could find the root issue in the
`nu_engine::glob_from` function. It uses `std::path::Path::canonicalize`
some layers down and that may return an `std::io::Error`. All these
errors were handled as "directory not found" which will be translated to
"file not found" in the `open` command. To fix this, I handled the
`PermssionDenied` error kind of the io error and passed that down. Now
trying to `open` a file from a directory with no permissions returns a
"permission denied" error.

Before/After:

![image](https://github.com/user-attachments/assets/168cea24-36a6-4c66-98c9-f7ccfa2ea826)

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That error is fixed, so correct error message.

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fixes #14528

crates/nu-command/src/filesystem/open.rs

@@ -91,6 +91,21 @@ impl Command for Open {
                         file: path.item.to_string(),
                         span,
                     },
+                    // that particular error in `nu_engine::glob_from` doesn't have a span attached
+                    // to it, so let's add it
+                    ShellError::GenericError {
+                        error,
+                        msg,
+                        span: _,
+                        help,
+                        inner,
+                    } if error.as_str() == "Permission denied" => ShellError::GenericError {
+                        error,
+                        msg,
+                        span: Some(arg_span),
+                        help,
+                        inner,
+                    },
                     _ => err,
                 })?
                 .1

crates/nu-engine/src/glob_from.rs

@@ -3,6 +3,7 @@ use nu_path::{canonicalize_with, expand_path_with};
 use nu_protocol::{NuGlob, ShellError, Span, Spanned};
 use std::{
     fs,
+    io::ErrorKind,
     path::{Component, Path, PathBuf},
 };
 
@@ -70,20 +71,32 @@ pub fn glob_from(
         if is_symlink {
             (path.parent().map(|parent| parent.to_path_buf()), path)
         } else {
-            let path = if let Ok(p) = canonicalize_with(path.clone(), cwd) {
-                if nu_glob::is_glob(p.to_string_lossy().as_ref()) {
+            let path = match canonicalize_with(path.clone(), cwd) {
+                Ok(p) if nu_glob::is_glob(p.to_string_lossy().as_ref()) => {
                     // our path might contain glob metacharacters too.
                     // in such case, we need to escape our path to make
                     // glob work successfully
                     PathBuf::from(nu_glob::Pattern::escape(&p.to_string_lossy()))
-                } else {
-                    p
                 }
-            } else {
-                return Err(ShellError::DirectoryNotFound {
-                    dir: path.to_string_lossy().to_string(),
-                    span: pattern.span,
-                });
+                Ok(p) => p,
+                Err(err) => {
+                    return match err.kind() {
+                        ErrorKind::PermissionDenied => Err(ShellError::GenericError {
+                            error: "Permission denied".into(),
+                            msg: err.to_string(),
+                            span: None,
+                            help: None,
+                            inner: vec![],
+                        }),
+                        // Previously, all these errors were treated as "directory not found."
+                        // Now, permission denied errors are handled separately.
+                        // TODO: Refine handling of I/O errors for more precise responses.
+                        _ => Err(ShellError::DirectoryNotFound {
+                            dir: path.to_string_lossy().to_string(),
+                            span: pattern.span,
+                        }),
+                    };
+                }
             };
             (path.parent().map(|parent| parent.to_path_buf()), path)
         }