#!/usr/bin/env drgn
"""
Monitor tmpfs superblocks to detect orphaned/leaked tmpfs filesystems.

Run with: sudo drgn -s /path/to/vmlinux monitor_tmpfs.py

This script lists all tmpfs superblocks and shows which ones have
NULL mount namespaces (orphaned) or are otherwise in unusual states.
"""

from drgn import container_of
from drgn.helpers.linux.list import hlist_for_each_entry, list_for_each_entry

def get_mount_info(sb):
    """Get mount information for a superblock"""
    mounts = []
    try:
        for mnt in list_for_each_entry('struct mount', sb.s_mounts.address_of_(), 'mnt_instance'):
            try:
                mnt_ns = mnt.mnt_ns
                mnt_ns_addr = mnt_ns.value_() if mnt_ns else 0

                # Get device name
                devname = mnt.mnt_devname.string_().decode('utf-8', errors='replace') if mnt.mnt_devname else "?"

                # Get mount point
                mnt_mountpoint = mnt.mnt_mountpoint
                if mnt_mountpoint:
                    name = mnt_mountpoint.d_name.name.string_().decode('utf-8', errors='replace')
                else:
                    name = "?"

                mounts.append({
                    'mnt_ns': mnt_ns_addr,
                    'devname': devname,
                    'mountpoint': name,
                    'mnt_addr': mnt.value_()
                })
            except:
                continue
    except:
        pass
    return mounts


def main():
    # Get the tmpfs/shmem filesystem type
    shmem_fs_type = prog['shmem_fs_type']

    print("=" * 80)
    print("tmpfs Superblock Monitor")
    print("=" * 80)
    print()

    # Collect all tmpfs superblocks
    tmpfs_sbs = []
    for sb in hlist_for_each_entry('struct super_block', shmem_fs_type.fs_supers, 's_instances'):
        tmpfs_sbs.append(sb)

    print(f"Found {len(tmpfs_sbs)} tmpfs superblocks\n")

    orphaned = []
    normal = []

    for sb in tmpfs_sbs:
        sb_addr = sb.value_()
        s_dev = sb.s_dev.value_()
        s_active = sb.s_active.counter.value_()

        mounts = get_mount_info(sb)

        # Check if any mount has NULL namespace
        has_orphaned = any(m['mnt_ns'] == 0 for m in mounts)
        has_normal = any(m['mnt_ns'] != 0 for m in mounts)

        info = {
            'sb': sb,
            'sb_addr': sb_addr,
            's_dev': s_dev,
            's_active': s_active,
            'mounts': mounts,
            'has_orphaned': has_orphaned
        }

        if has_orphaned and not has_normal:
            orphaned.append(info)
        else:
            normal.append(info)

    # Print orphaned superblocks first (these are the leaked ones)
    if orphaned:
        print("!!! ORPHANED tmpfs SUPERBLOCKS (potential leaks) !!!")
        print("-" * 80)
        for info in orphaned:
            sb = info['sb']
            print(f"Superblock: 0x{info['sb_addr']:016x}")
            print(f"  s_dev: {info['s_dev']}")
            print(f"  s_active: {info['s_active']}")

            # Try to list some files
            try:
                root = sb.s_root
                if root:
                    print("  Root dentry contents:")
                    count = 0
                    for child in hlist_for_each_entry('struct dentry', root.d_children, 'd_sib'):
                        name = child.d_name.name.string_().decode('utf-8', errors='replace')
                        inode = child.d_inode
                        if inode:
                            size = inode.i_size.value_()
                            print(f"    - {name} ({size} bytes)")
                            count += 1
                            if count >= 10:
                                print("    ... (more files)")
                                break
            except Exception as e:
                print(f"  Error listing files: {e}")

            for m in info['mounts']:
                print(f"  Mount: {m['devname']} -> {m['mountpoint']}")
                print(f"         mnt_ns: 0x{m['mnt_ns']:016x} (NULL = orphaned)")
            print()
        print()

    # Print summary of normal superblocks
    print("Normal tmpfs superblocks:")
    print("-" * 80)
    for info in normal:
        devnames = set(m['devname'] for m in info['mounts'])
        namespaces = set(m['mnt_ns'] for m in info['mounts'])
        print(f"0x{info['sb_addr']:016x} s_dev={info['s_dev']:<4} "
              f"active={info['s_active']:<3} "
              f"mounts={len(info['mounts']):<3} "
              f"devnames={devnames}")

    print()
    print("=" * 80)
    print(f"Summary: {len(orphaned)} orphaned, {len(normal)} normal")
    if orphaned:
        print("WARNING: Orphaned tmpfs superblocks detected - these may be leaking memory!")
    print("=" * 80)


if __name__ == "__main__":
    main()