Bug: ls /tmp shows mount points (/dev, /proc, /tmp) instead of its contents

[pbalduino]

Bug Description

When running ls /tmp, the output incorrectly shows mount points (/dev, /proc, and /tmp itself) instead of the actual contents of the /tmp directory.

Expected Behavior

ls /tmp should show the files and directories contained within /tmp, not the global filesystem mount points.

Actual Behavior

$ ls /tmp
/dev
/proc
/tmp

The listing shows mount points that belong at the root level, not the contents of /tmp.

Root Cause

The issue is in the VFS layer's vfs_list() function. The "mountpoint injection" step runs for any filesystem root (when relative == "/"), not just the global root.

When you list /tmp:

1. The code resolves to the tmpfs root (which is / relative to that filesystem)
2. The mount iteration loop replays every mount including the one being listed
3. Result: /tmp shows all mount points instead of its own contents

Technical Analysis

The mountpoint injection logic in vfs_list() should:

• Only append mount points when listing the global root (/)
• Skip mount points when listing subdirectory roots of mounted filesystems

Current behavior:

// Simplified pseudocode
if (relative == "/") {
    // This runs for ANY filesystem root, not just global root!
    for (mount in all_mounts) {
        append_mount_to_results(mount);
    }
}

Proposed Fix

Tighten the mountpoint injection logic with one of these approaches:

Option 1: Check if path is global root

// Only inject mounts when listing the actual global root
if (strcmp(resolved_path, "/") == 0 && relative == "/") {
    for (mount in all_mounts) {
        append_mount_to_results(mount);
    }
}

Option 2: Skip current mount

if (relative == "/") {
    for (mount in all_mounts) {
        // Skip the mount we're currently listing
        if (strcmp(mount->path, current_listing_path) == 0) {
            continue;
        }
        append_mount_to_results(mount);
    }
}

Impact

• Severity: Medium - breaks basic filesystem navigation expectations
• User Experience: Confusing for users expecting standard Unix behavior
• Workaround: None - incorrect behavior on every tmpfs listing
• Affected: All mounted filesystems when listing their root directories

Files Affected

• src/kernel/fs/vfs/vfs.c - vfs_list() function
• Mountpoint injection logic

Reproduction

# This should show /tmp contents but shows mount points instead
$ ls /tmp

# Compare with expected behavior:
$ ls /        # Should show mount points (correct)
$ ls /proc    # Should show proc contents, not mount points (currently broken)
$ ls /dev     # Should show dev contents, not mount points (currently broken)

Testing Requirements

After fix:

• ls / shows mount points: /dev, /proc, /tmp, etc. ✓
• ls /tmp shows tmpfs contents only (no mount points)
• ls /proc shows procfs contents only (no mount points)
• ls /dev shows devfs contents only (no mount points)
• Nested mounts work correctly

Priority

Medium - Functional bug affecting filesystem navigation, but workaround exists (use full paths or navigate into subdirectories).

Related Issues

• Implement VFS (Virtual File System) layer #65 - VFS layer implementation
• Implement tmpfs/ramfs in-memory filesystem for /tmp #151 - tmpfs validation (may have revealed this issue)