require 'fiddle'
require 'fiddle/import'

class File
  module Statfs
    Magics = {}
    Line = <<~EOF
      ADFS	0xadf5
      AFFS	0xadff
      AFS	0x5346414F
      AUTOFS	0x0187
      CODA	0x73757245
      CRAMFS		0x28cd3d45
      CRAMFS_WEND	0x453dcd28
      DEBUGFS	0x64626720
      SECURITYFS	0x73636673
      SELINUX		0xf97cff8c
      SMACK		0x43415d53
      RAMFS		0x858458f6
      TMPFS		0x01021994
      HUGETLBFS 	0x958458f6
      SQUASHFS		0x73717368
      ECRYPTFS	0xf15f
      EFS		0x414A53
      EROFS_V1	0xE0F5E1E2
      EXT2	0xEF53
      EXT3	0xEF53
      XENFS	0xabba1974
      EXT4	0xEF53
      BTRFS	0x9123683E
      NILFS	0x3434
      F2FS	0xF2F52010
      HPFS	0xf995e849
      ISOFS	0x9660
      JFFS2	0x72b6
      XFS		0x58465342
      PSTOREFS		0x6165676C
      EFIVARFS		0xde5e81e4
      HOSTFS	0x00c0ffee
      OVERLAYFS	0x794c7630
      MINIX	0x137F
      MINIX2	0x138F
      MINIX2	0x2468
      MINIX22	0x2478
      MINIX3	0x4d5a
      MSDOS	0x4d44
      NCP		0x564c
      NFS		0x6969
      OCFS2	0x7461636f
      OPENPROM	0x9fa1
      QNX4	0x002f
      QNX6	0x68191122
      AFS_FS		0x6B414653
      REISERFS	0x52654973
      REISERFS	"ReIsErFs"
      REISER2FS	"ReIsEr2Fs"
      REISER2FS_JR	"ReIsEr3Fs"
      SMB		0x517B
      CGROUP	0x27e0eb
      CGROUP2	0x63677270
      RDTGROUP	0x7655821
      STACK_END		0x57AC6E9D
      TRACEFS          0x74726163
      V9FS		0x01021997
      BDEVFS            0x62646576
      DAXFS             0x64646178
      BINFMTFS          0x42494e4d
      DEVPTS	0x1cd1
      BINDERFS	0x6c6f6f70
      FUTEXFS	0xBAD1DEA
      PIPEFS            0x50495045
      PROC	0x9fa0
      SOCKFS		0x534F434B
      SYSFS		0x62656572
      USBDEVICE	0x9fa2
      MTD_INODE_FS      0x11307854
      ANON_INODE_FS	0x09041934
      BTRFS_TEST	0x73727279
      NSFS		0x6e736673
      BPF_FS		0xcafe4a11
      AAFS		0x5a3c69f0
      ZONEFS		0x5a4f4653
      UDF		0x15013346
      BALLOON_KVM	0x13661366
      ZSMALLOC		0x58295829
      DMA_BUF		0x444d4142
      DEVMEM		0x454d444d
      Z3FOLD		0x33
      PPC_CMM 0xc7571590
    EOF
    Line.each_line do |l|
      n, v = l.split(/\s+/)[0..1]
      v =
        case v
        when /^0x(\h+)$/ then $1.to_i 16
        when /^"([^"]+)"$/ then $1
        else raise "Unknown value: #$1"
        end
      Magics[v] = n.downcase.to_sym
    end

    extend Fiddle::Importer
    dlload Fiddle.dlopen( nil)

    Struct_statfs = struct <<~EOS
      long type,
      long bsize,
      unsigned long blocks,
      unsigned long bfree,
      unsigned long bavail,
      unsigned long files,
      unsigned long ffree,
      int fsid[2],
      long namelen,
      long frsize,
      long flags,
      long spare[4]
    EOS

    class Struct_statfs
      def fstypename
        Magics[type]
      end

      def to_h
        {type: type, fstypename: fstypename, bsize: bsize, blocks: blocks, bfree: bfree, bavail: bavail, files: files, ffree: ffree, fsid: fsid, namelen: namelen, frsize: frsize, flags: flags, spare: spare}
      end
    end

    StatfsFun = Fiddle::Function.new handler['statfs'], [Fiddle::TYPE_VOIDP, Fiddle::TYPE_VOIDP], Fiddle::TYPE_INT
    #extern 'int statfs( const char *__file, struct statfs *__buf)'

    def self.new file
      buf = Struct_statfs.malloc
      val = StatfsFun.call file, buf
      raise SystemCallError.new( "statfs(#{file.inspect})", Fiddle.last_error)  unless val == 0
      buf
    end
  end
end