Fix cursor icon search paths to follow XDG Icon Theme Specification

[Copilot]

Mir's cursor icon search path (XCURSORPATH) was a hardcoded legacy list that omitted $XDG_DATA_DIRS/icons — meaning /usr/local/share/icons and any custom data dirs were never searched.

Per the XDG Icon Theme Specification, apps should look in $HOME/.icons, $XDG_DATA_DIRS/icons, and /usr/share/pixmaps (in that order).

What's new?

• Added _XcursorBuildXdgPath() in src/miral/xcursor.c that dynamically constructs the cursor search path when XCURSOR_PATH is not set
• New default search order (no duplicate entries):
  1. $HOME/.icons (backwards compat)
  2. $XDG_DATA_DIRS/icons — expanded per-entry; defaults to /usr/local/share/icons:/usr/share/icons when XDG_DATA_DIRS is unset
  3. /usr/share/pixmaps
  4. Truly legacy-only fallback entries (~/.cursors, /usr/share/cursors/xorg-x11, ICONDIR) via new XCURSORLEGACYPATH macro — entries already covered by the XDG prefix are excluded to avoid redundant filesystem searches
• XCURSOR_PATH env var override continues to take priority (unchanged behaviour)
• Full XCURSORPATH macro retained as last-resort fallback when dynamic path allocation fails
• Path is built once per process lifetime; snprintf with remaining-buffer tracking used throughout
• Variables declared at the point of initialization throughout _XcursorBuildXdgPath()

How to test

Set a cursor theme via miral::CursorTheme and verify cursors load from paths under $XDG_DATA_DIRS/icons (e.g. /usr/local/share/icons/<theme>/cursors/). Setting a custom XDG_DATA_DIRS should cause that directory's icons subtree to be searched.

Checklist

• Tests added and pass
• Adequate documentation added
• (optional) Added Screenshots or videos

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Cursor theming may need a refresh</issue_title>
<issue_description>Mir looks for icons in the wrong places.

By default it uses some internal cursor images

When miral::CursorTheme is used then it searches XCURSOR_PATH or ~/.icons:/usr/share/icons:/usr/share/pixmaps:~/.cursors:/usr/share/cursors/xorg-x11:/usr/X11R6/lib/X11/icons, which is not quite right now:

Icons and themes are looked for in a set of directories. By default, apps should look in $HOME/.icons (for backwards compatibility), in $XDG_DATA_DIRS/icons and in /usr/share/pixmaps (in that order). https://specifications.freedesktop.org/icon-theme-spec/latest/

We likely want to correct where we search and use that as a default. (The current default becoming a fallback if there are no cursors on the system)</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Cursor theming may need a refresh #3775

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.

[AlanGriffiths]

@copilot it is poor style to declare variables before they can be initialized

[Copilot]

@copilot it is poor style to declare variables before they can be initialized

Fixed in bc8d61c — variables are now declared at the point where they can be initialized, using for-init declarations for the loop variables and int const written declared inside each block.

[github-actions]

TICS Quality Gate

✔️ Passed

mir

Coding Standards: ✔️ Passed

✔️ Condition “No new Coding Standard Violations for level 1, 2, 3 with respect to Previous analysis” passed.

See the results in the TICS Viewer

The following files have been checked for this project

• src/miral/xcursor.c

TICS / TICS / Run TICS analysis

[Copilot]

Pull request overview

This PR fixes cursor icon search paths in src/miral/xcursor.c to comply with the XDG Icon Theme Specification. Previously, Mir used a hardcoded XCURSORPATH that omitted $XDG_DATA_DIRS/icons. The fix introduces a dynamic path builder that constructs the correct XDG-spec-compliant search order at runtime, falling back to the legacy path.

Changes:

• Added _XcursorBuildXdgPath() that dynamically constructs the cursor search path per the XDG Icon Theme spec: $HOME/.icons, $XDG_DATA_DIRS/icons (expanded), /usr/share/pixmaps, then legacy XCURSORPATH entries
• XcursorLibraryPath() updated to call _XcursorBuildXdgPath() when XCURSOR_PATH env var is not set, with XCURSORPATH macro as last resort fallback

[Copilot]

The generated path contains duplicate entries. /usr/share/pixmaps is explicitly added at line 667 (before XCURSORPATH), but XCURSORPATH itself already contains /usr/share/pixmaps. Similarly, when using the default XDG_DATA_DIRS, /usr/share/icons appears both in the XDG expansion and in XCURSORPATH. Additionally, $HOME/.icons (expanded on line 648) appears again as ~/.icons in the legacy XCURSORPATH fallback (which gets tilde-expanded at runtime in _XcursorBuildThemeDir).

These duplicates cause each directory to be searched twice, resulting in redundant filesystem operations. To avoid this, /usr/share/pixmaps could be stripped from XCURSORPATH before appending, or the snprintf format on line 667 could use a trimmed version of the legacy path that excludes entries already covered by the XDG prefix entries.

[AlanGriffiths]

@copilot apply changes based on this feedback

[Copilot]

Fixed in 790607b. Introduced XCURSORLEGACYPATH containing only the entries not already covered by the XDG prefix (~/.cursors:/usr/share/cursors/xorg-x11:ICONDIR) and used that in _XcursorBuildXdgPath instead of the full XCURSORPATH. The generated path now has no duplicates — ~/.icons, $XDG_DATA_DIRS/icons entries, and /usr/share/pixmaps each appear exactly once. The full XCURSORPATH is retained as the last-resort fallback when malloc fails.