#!/usr/bin/env python3
# SPDX-License-Identifier: LGPL-2.1-or-later

import os
import subprocess
import sys

NAME_TO_MAGIC = {
    'apparmorfs':      ['AAFS_MAGIC'],
    'adfs':            ['ADFS_SUPER_MAGIC'],
    'affs':            ['AFFS_SUPER_MAGIC'],
    'afs':             ['AFS_FS_MAGIC',
                        'AFS_SUPER_MAGIC'],
    'anon_inodefs':    ['ANON_INODE_FS_MAGIC'],
    'autofs':          ['AUTOFS_SUPER_MAGIC'],
    'balloon-kvm':     ['BALLOON_KVM_MAGIC'],
    'bcachefs':        ['BCACHEFS_SUPER_MAGIC'],
    'bdev':            ['BDEVFS_MAGIC'],
    'binder':          ['BINDERFS_SUPER_MAGIC'],
    'binfmt_misc':     ['BINFMTFS_MAGIC'],
    'bpf':             ['BPF_FS_MAGIC'],
    'btrfs':           ['BTRFS_SUPER_MAGIC'],
    'btrfs_test_fs':   ['BTRFS_TEST_MAGIC'],
    # cpuset's magic got reassigned to cgroupfs
    'cpuset':          ['CGROUP_SUPER_MAGIC'],
    'ceph':            ['CEPH_SUPER_MAGIC'],
    'cgroup2':         ['CGROUP2_SUPER_MAGIC'],
    # note that the cgroupfs magic got reassigned from cpuset
    'cgroup':          ['CGROUP_SUPER_MAGIC'],
    'cifs':            ['CIFS_SUPER_MAGIC',
                        'SMB2_SUPER_MAGIC'],
    'coda':            ['CODA_SUPER_MAGIC'],
    'configfs':        ['CONFIGFS_MAGIC'],
    'cramfs':          ['CRAMFS_MAGIC'],
    'dax':             ['DAXFS_MAGIC'],
    'debugfs':         ['DEBUGFS_MAGIC'],
    'devmem':          ['DEVMEM_MAGIC'],
    'devpts':          ['DEVPTS_SUPER_MAGIC'],
    # devtmpfs is just a special instance of tmpfs, hence it reports its magic
    'devtmpfs':        ['TMPFS_MAGIC'],
    'dmabuf':          ['DMA_BUF_MAGIC'],
    'ecryptfs':        ['ECRYPTFS_SUPER_MAGIC'],
    'efivarfs':        ['EFIVARFS_MAGIC'],
    'efs':             ['EFS_SUPER_MAGIC'],
    'erofs':           ['EROFS_SUPER_MAGIC_V1'],
    # ext2 + ext3 + ext4 use the same magic
    'ext2':            ['EXT2_SUPER_MAGIC'],
    'ext3':            ['EXT3_SUPER_MAGIC'],
    'ext4':            ['EXT4_SUPER_MAGIC'],
    'exfat':           ['EXFAT_SUPER_MAGIC'],
    'f2fs':            ['F2FS_SUPER_MAGIC'],
    # fuseblk is so closely related to fuse that it shares the same magic
    'fuseblk':         ['FUSE_SUPER_MAGIC'],
    'fuse':            ['FUSE_SUPER_MAGIC'],
    'fusectl':         ['FUSE_CTL_SUPER_MAGIC'],
    # gfs is an old version of gfs2 and reuses the magic
    'gfs':             ['GFS2_MAGIC'],
    'gfs2':            ['GFS2_MAGIC'],
    'hostfs':          ['HOSTFS_SUPER_MAGIC'],
    'hpfs':            ['HPFS_SUPER_MAGIC'],
    'hugetlbfs':       ['HUGETLBFS_MAGIC'],
    'iso9660':         ['ISOFS_SUPER_MAGIC'],
    'jffs2':           ['JFFS2_SUPER_MAGIC'],
    'minix':           ['MINIX_SUPER_MAGIC',
                        'MINIX_SUPER_MAGIC2',
                        'MINIX2_SUPER_MAGIC',
                        'MINIX2_SUPER_MAGIC2',
                        'MINIX3_SUPER_MAGIC'],
    'mqueue':          ['MQUEUE_MAGIC'],
    # msdos is an older legacy version of vfat, shares the magic
    'msdos':           ['MSDOS_SUPER_MAGIC'],
    # ncp/ncpfs have been removed from the kernel, but ncpfs was the official name
    'ncp':             ['NCP_SUPER_MAGIC'],
    'ncpfs':           ['NCP_SUPER_MAGIC'],
    # nfs is the old version of nfs4, and they share the same magic
    'nfs':             ['NFS_SUPER_MAGIC'],
    'nfs4':            ['NFS_SUPER_MAGIC'],
    'nilfs2':          ['NILFS_SUPER_MAGIC'],
    'nsfs':            ['NSFS_MAGIC'],
    'ntfs':            ['NTFS_SB_MAGIC'],
    'ntfs3':           ['NTFS3_SUPER_MAGIC'],
    'ocfs2':           ['OCFS2_SUPER_MAGIC'],
    'openpromfs':      ['OPENPROM_SUPER_MAGIC'],
    'orangefs':        ['ORANGEFS_DEVREQ_MAGIC'],
    'overlay':         ['OVERLAYFS_SUPER_MAGIC'],
    'pidfs':           ['PID_FS_MAGIC'],
    'pipefs':          ['PIPEFS_MAGIC'],
    'ppc-cmm':         ['PPC_CMM_MAGIC'],
    'proc':            ['PROC_SUPER_MAGIC'],
    'pstore':          ['PSTOREFS_MAGIC'],
    # pvfs2 is the old version of orangefs
    'pvfs2':           ['ORANGEFS_DEVREQ_MAGIC'],
    'qnx4':            ['QNX4_SUPER_MAGIC'],
    'qnx6':            ['QNX6_SUPER_MAGIC'],
    'ramfs':           ['RAMFS_MAGIC'],
    'resctrl':         ['RDTGROUP_SUPER_MAGIC'],
    'reiserfs':        ['REISERFS_SUPER_MAGIC'],
    'rpc_pipefs':      ['RPC_PIPEFS_SUPER_MAGIC'],
    'secretmem':       ['SECRETMEM_MAGIC'],
    'securityfs':      ['SECURITYFS_MAGIC'],
    'selinuxfs':       ['SELINUX_MAGIC'],
    'shiftfs':         ['SHIFTFS_MAGIC'],
    'smackfs':         ['SMACK_MAGIC'],
    # smb3 is an alias for cifs
    'smb3':            ['CIFS_SUPER_MAGIC'],
    # smbfs was removed from the kernel in 2010, the magic remains
    'smbfs':           ['SMB_SUPER_MAGIC'],
    'sockfs':          ['SOCKFS_MAGIC'],
    'squashfs':        ['SQUASHFS_MAGIC'],
    'sysfs':           ['SYSFS_MAGIC'],
    # note that devtmpfs shares the same magic with tmpfs, given it is just a special named instance of it.
    'tmpfs':           ['TMPFS_MAGIC'],
    'tracefs':         ['TRACEFS_MAGIC'],
    'udf':             ['UDF_SUPER_MAGIC'],
    'usbdevfs':        ['USBDEVICE_SUPER_MAGIC'],
    'vboxsf':          ['VBOXSF_SUPER_MAGIC'],
    # note that msdos shares the same magic (and is the older version)
    'vfat':            ['MSDOS_SUPER_MAGIC'],
    'v9fs':            ['V9FS_MAGIC'],
    'xenfs':           ['XENFS_SUPER_MAGIC'],
    'xfs':             ['XFS_SUPER_MAGIC'],
    'z3fold':          ['Z3FOLD_MAGIC'],
    'zonefs':          ['ZONEFS_MAGIC'],
    'zsmalloc':        ['ZSMALLOC_MAGIC'],
}

# System magics are sometimes not unique, because file systems got new
# revisions or got renamed. Let's prefer newer over older here, and thus ignore
# the old names.
OBSOLETE_NAMES =  {
    'cpuset',    # magic taken over by cgroupfs
    'devtmpfs',  # not a file system of its own, but just a "named superblock" of tmpfs
    'ext2',      # ext4 is the newest revision of ext2 + ext3
    'ext3',
    'fuseblk',   # closely related to fuse; they share a single magic, but the latter is more common
    'gfs',       # magic taken over by gfs2
    'msdos',     # vfat is the newest revision of msdos
    'ncp',       # ncpfs (not ncp) was the last name of the netware 'file_system_type'
                 # name before it was removed in 2018
    'nfs',       # nfs4 is the newest revision of nfs
    'pvfs2',     # orangefs is the new name of pvfs2
    'smb3',      # smb3 is an alias for cifs
}

FILESYSTEM_SETS = [
    (
        "@basic-api",
        "Basic filesystem API",
        "cgroup",
        "cgroup2",
        "devpts",
        "devtmpfs",
        "mqueue",
        "proc",
        "sysfs",
    ),
    (
        "@anonymous",
        "Anonymous inodes",
        "anon_inodefs",
        "pipefs",
        "sockfs",
    ),
    (
        "@application",
        "Application virtual filesystems",
        "autofs",
        "fuse",
        "overlay",
    ),
    (
        "@auxiliary-api",
        "Auxiliary filesystem API",
        "binfmt_misc",
        "configfs",
        "efivarfs",
        "fusectl",
        "hugetlbfs",
        "rpc_pipefs",
        "securityfs",
    ),
    (
        "@common-block",
        "Common block device filesystems",
        "btrfs",
        "erofs",
        "exfat",
        "ext4",
        "f2fs",
        "iso9660",
        "ntfs3",
        "squashfs",
        "udf",
        "vfat",
        "xfs",
    ),
    (
        "@historical-block",
        "Historical block device filesystems",
        "ext2",
        "ext3",
        "minix",
    ),
    (
        "@network",
        "Well-known network filesystems",
        "afs",
        "ceph",
        "cifs",
        "gfs",
        "gfs2",
        "ncp",
        "ncpfs",
        "nfs",
        "nfs4",
        "ocfs2",
        "orangefs",
        "pvfs2",
        "smb3",
        "smbfs",
    ),
    (
        "@privileged-api",
        "Privileged filesystem API",
        "bpf",
        "debugfs",
        "pstore",
        "tracefs",
    ),
    (
        "@security",
        "Security/MAC API VFS",
        "apparmorfs",
        "selinuxfs",
        "smackfs",
    ),
    (
        "@temporary",
        "Temporary filesystems",
        "ramfs",
        "tmpfs",
    ),
    (
        "@known",
        "All known filesystems declared in the kernel",
        *NAME_TO_MAGIC.keys(),
    ),
]

def generate_gperf():
    print("""\
/* SPDX-License-Identifier: LGPL-2.1-or-later */
%{
#if __GNUC__ >= 15
_Pragma("GCC diagnostic ignored \\"-Wzero-as-null-pointer-constant\\"")
#endif
#include <linux/magic.h>

#include "filesystems.h"
#include "stat-util.h"

struct FilesystemMagic {
        const char *name;
        statfs_f_type_t magic[FILESYSTEM_MAGIC_MAX];
};
%}
struct FilesystemMagic;
%language=ANSI-C
%define hash-function-name filesystems_gperf_hash
%define lookup-function-name filesystems_gperf_lookup
%define slot-name name
%readonly-tables
%omit-struct-type
%struct-type
%includes
%%""")
    for name, magics in NAME_TO_MAGIC.items():
        print(f"{name + ',':16} {{{', '.join(magics)}}}")

def generate_fs_type_to_string():
    print("""\
#include <linux/magic.h>
#include "filesystems.h"

/* PROJECT_FILE, which is used by log_xyz() thus also used by assert_not_reached(), cannot be used in
 * generated files, as the build directory may be outside of the source directory. */
#undef PROJECT_FILE
#define PROJECT_FILE __FILE__

const char* fs_type_to_string(statfs_f_type_t magic) {
        switch (magic) {""")

    for name, magics in NAME_TO_MAGIC.items():
        if name in OBSOLETE_NAMES:
            continue
        for magic in magics:
            print(f'        case (statfs_f_type_t) {magic}:')
        print(f'                return "{name}";')

    print("""\
        }
        return NULL;
}""")

def generate_fs_in_group():
    print('bool fs_in_group(const struct statfs *st, FilesystemGroups fs_group) {')
    print('        switch (fs_group) {')

    for name, _, *filesystems in FILESYSTEM_SETS:
        magics = sorted(set(sum((NAME_TO_MAGIC[fs] for fs in filesystems), [])))
        enum = 'FILESYSTEM_SET_' + name[1:].upper().replace('-', '_')
        print(f'        case {enum}:')
        opts = '\n                    || '.join(f'F_TYPE_EQUAL(st->f_type, {magic})'
                                                for magic in magics)
        print(f'                return {opts};')

    print('        default: assert_not_reached();')
    print('        }')
    print('}')

def generate_filesystem_sets():
    print('const FilesystemSet filesystem_sets[_FILESYSTEM_SET_MAX] = {')

    for name, desc, *filesystems in FILESYSTEM_SETS:
        enum = 'FILESYSTEM_SET_' + name[1:].upper().replace('-', '_')

        print(f'        [{enum}] = {{')
        print(f'                .name = "{name}",')
        print(f'                .help = "{desc}",')
        print(f'                .value =')
        for filesystem in filesystems:
            print(f'                "{filesystem}\\0"')
        print('        },')

    print('};')

def magic_defines():
    cpp = os.environ['CPP'].split()
    out = subprocess.check_output(
        [*cpp, '-dM', '-include', 'linux/magic.h', '-'],
        stdin=subprocess.DEVNULL,
        text=True)
    for line in out.splitlines():
        _, name, *rest = line.split()
        if ('_MAGIC' in name
            and rest and rest[0].startswith('0x')
            and name not in {
                'STACK_END_MAGIC',
                'MTD_INODE_FS_MAGIC',
                'FUTEXFS_SUPER_MAGIC',
                'CRAMFS_MAGIC_WEND',
            }):
            yield name

def check():
    kernel_magics = set(magic_defines())
    our_magics = set(sum(NAME_TO_MAGIC.values(), []))
    extra = kernel_magics - our_magics
    if extra:
        sys.exit(f"kernel knows additional filesystem magics: {', '.join(sorted(extra))}")

if __name__ == '__main__':
    for arg in sys.argv[1:]:
        if arg == 'gperf':
            generate_gperf()
        elif arg == 'fs-type-to-string':
            generate_fs_type_to_string()
        elif arg == 'filesystem-sets':
            generate_filesystem_sets()
        elif arg == 'fs-in-group':
            generate_fs_in_group()
        elif arg == 'check':
            check()
        else:
            raise ValueError
