diff options
Diffstat (limited to 'sandbox/vfs/mountinfo.go')
| -rw-r--r-- | sandbox/vfs/mountinfo.go | 213 |
1 files changed, 137 insertions, 76 deletions
diff --git a/sandbox/vfs/mountinfo.go b/sandbox/vfs/mountinfo.go index df2940a4..b2634128 100644 --- a/sandbox/vfs/mountinfo.go +++ b/sandbox/vfs/mountinfo.go @@ -5,6 +5,7 @@ import ( "errors" "fmt" "io" + "iter" "strconv" "strings" "syscall" @@ -18,13 +19,23 @@ var ( ) type ( - // MountInfo represents a /proc/pid/mountinfo document. + // A MountInfoDecoder reads and decodes proc_pid_mountinfo(5) entries from an input stream. + MountInfoDecoder struct { + s *bufio.Scanner + m *MountInfo + + current *MountInfo + parseErr error + complete bool + } + + // MountInfo represents the contents of a proc_pid_mountinfo(5) document. MountInfo struct { Next *MountInfo MountInfoEntry } - // MountInfoEntry represents a line in /proc/pid/mountinfo. + // MountInfoEntry represents a proc_pid_mountinfo(5) entry. MountInfoEntry struct { // mount ID: a unique ID for the mount (may be reused after umount(2)). ID int `json:"id"` @@ -77,95 +88,145 @@ func (e *MountInfoEntry) Flags() (flags uintptr, unmatched []string) { return } -// ParseMountInfo parses a mountinfo file according to proc_pid_mountinfo(5). -func ParseMountInfo(r io.Reader) (*MountInfo, int, error) { - var m, cur *MountInfo - s := bufio.NewScanner(r) +// NewMountInfoDecoder returns a new decoder that reads from r. +// +// The decoder introduces its own buffering and may read data from r beyond the mountinfo entries requested. +func NewMountInfoDecoder(r io.Reader) *MountInfoDecoder { + return &MountInfoDecoder{s: bufio.NewScanner(r)} +} - var n int - for s.Scan() { - n++ +func (d *MountInfoDecoder) Decode(v **MountInfo) (err error) { + for d.scan() { + } + err = d.Err() + if err == nil { + *v = d.m + } + return +} - if cur == nil { - m = new(MountInfo) - cur = m - } else { - cur.Next = new(MountInfo) - cur = cur.Next +// Entries returns an iterator over mountinfo entries. +func (d *MountInfoDecoder) Entries() iter.Seq[*MountInfoEntry] { + return func(yield func(*MountInfoEntry) bool) { + for cur := d.m; cur != nil; cur = cur.Next { + if !yield(&cur.MountInfoEntry) { + return + } } - - // prevent proceeding with misaligned fields due to optional fields - f := strings.Split(s.Text(), " ") - if len(f) < 10 { - return nil, -1, ErrMountInfoFields + for d.scan() { + if !yield(&d.current.MountInfoEntry) { + return + } } + } +} - // 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue - // (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) +func (d *MountInfoDecoder) Err() error { + if err := d.s.Err(); err != nil { + return err + } + return d.parseErr +} - // (1) id - if id, err := strconv.Atoi(f[0]); err != nil { // 0 - return nil, -1, err - } else { - cur.ID = id - } +func (d *MountInfoDecoder) scan() bool { + if d.complete { + return false + } + if !d.s.Scan() { + d.complete = true + return false + } - // (2) parent - if parent, err := strconv.Atoi(f[1]); err != nil { // 1 - return nil, -1, err - } else { - cur.Parent = parent - } + m := new(MountInfo) + if err := parseMountInfoLine(d.s.Text(), &m.MountInfoEntry); err != nil { + d.parseErr = err + d.complete = true + return false + } - // (3) maj:min - if n, err := fmt.Sscanf(f[2], "%d:%d", &cur.Devno[0], &cur.Devno[1]); err != nil { - return nil, -1, err - } else if n != 2 { - // unreachable - return nil, -1, ErrMountInfoDevno - } + if d.current == nil { + d.m = m + d.current = d.m + } else { + d.current.Next = m + d.current = d.current.Next + } + return true +} - // (4) mountroot - cur.Root = Unmangle(f[3]) - if cur.Root == "" { - return nil, -1, ErrMountInfoEmpty - } +func parseMountInfoLine(s string, ent *MountInfoEntry) error { + // prevent proceeding with misaligned fields due to optional fields + f := strings.Split(s, " ") + if len(f) < 10 { + return ErrMountInfoFields + } - // (5) target - cur.Target = Unmangle(f[4]) - if cur.Target == "" { - return nil, -1, ErrMountInfoEmpty - } + // 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue + // (1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11) - // (6) vfs options (fs-independent) - cur.VfsOptstr = Unmangle(f[5]) - if cur.VfsOptstr == "" { - return nil, -1, ErrMountInfoEmpty - } + // (1) id + if id, err := strconv.Atoi(f[0]); err != nil { // 0 + return err + } else { + ent.ID = id + } - // (7) optional fields, terminated by " - " - i := len(f) - 4 - cur.OptFields = f[6:i] + // (2) parent + if parent, err := strconv.Atoi(f[1]); err != nil { // 1 + return err + } else { + ent.Parent = parent + } - // (8) optional fields end marker - if f[i] != "-" { - return nil, -1, ErrMountInfoSep - } - i++ + // (3) maj:min + if n, err := fmt.Sscanf(f[2], "%d:%d", &ent.Devno[0], &ent.Devno[1]); err != nil { + return err + } else if n != 2 { + // unreachable + return ErrMountInfoDevno + } - // (9) FS type - cur.FsType = Unmangle(f[i]) - if cur.FsType == "" { - return nil, -1, ErrMountInfoEmpty - } - i++ + // (4) mountroot + ent.Root = Unmangle(f[3]) + if ent.Root == "" { + return ErrMountInfoEmpty + } + + // (5) target + ent.Target = Unmangle(f[4]) + if ent.Target == "" { + return ErrMountInfoEmpty + } + + // (6) vfs options (fs-independent) + ent.VfsOptstr = Unmangle(f[5]) + if ent.VfsOptstr == "" { + return ErrMountInfoEmpty + } - // (10) source -- maybe empty string - cur.Source = Unmangle(f[i]) - i++ + // (7) optional fields, terminated by " - " + i := len(f) - 4 + ent.OptFields = f[6:i] - // (11) fs options (fs specific) - cur.FsOptstr = Unmangle(f[i]) + // (8) optional fields end marker + if f[i] != "-" { + return ErrMountInfoSep } - return m, n, s.Err() + i++ + + // (9) FS type + ent.FsType = Unmangle(f[i]) + if ent.FsType == "" { + return ErrMountInfoEmpty + } + i++ + + // (10) source -- maybe empty string + ent.Source = Unmangle(f[i]) + i++ + + // (11) fs options (fs specific) + ent.FsOptstr = Unmangle(f[i]) + + return nil } |