diff options
Diffstat (limited to 'filesystem')
| -rw-r--r-- | filesystem/mountpoint.go | 124 |
1 files changed, 85 insertions, 39 deletions
diff --git a/filesystem/mountpoint.go b/filesystem/mountpoint.go index 3dc1934..c43e14e 100644 --- a/filesystem/mountpoint.go +++ b/filesystem/mountpoint.go @@ -22,27 +22,20 @@ package filesystem import ( + "bufio" "fmt" "io/ioutil" "log" "os" "path/filepath" "sort" + "strconv" "strings" "sync" "github.com/pkg/errors" ) -/* -#include <mntent.h> // setmntent, getmntent, endmntent - -// The file containing mountpoints info and how we should read it -const char* mountpoints_filename = "/proc/mounts"; -const char* read_mode = "r"; -*/ -import "C" - var ( // These maps hold data about the state of the system's mountpoints. mountsByPath map[string]*Mount @@ -57,38 +50,88 @@ var ( uuidDirectory = "/dev/disk/by-uuid" ) -// loadMountInfo populates the Mount mappings by parsing the filesystem -// description file using the getmntent functions. Returns ErrBadLoad if the -// Mount mappings cannot be populated. +// Unescape octal-encoded escape sequences in a string from the mountinfo file. +// The kernel encodes the ' ', '\t', '\n', and '\\' bytes this way. This +// function exactly inverts what the kernel does, including by preserving +// invalid UTF-8. +func unescapeString(str string) string { + var sb strings.Builder + for i := 0; i < len(str); i++ { + b := str[i] + if b == '\\' && i+3 < len(str) { + if parsed, err := strconv.ParseInt(str[i+1:i+4], 8, 8); err == nil { + b = uint8(parsed) + i += 3 + } + } + sb.WriteByte(b) + } + return sb.String() +} + +// Parse one line of /proc/self/mountinfo. +// +// The line contains the following space-separated fields: +// [0] mount ID +// [1] parent ID +// [2] major:minor +// [3] root +// [4] mount point +// [5] mount options +// [6...n-1] optional field(s) +// [n] separator +// [n+1] filesystem type +// [n+2] mount source +// [n+3] super options +// +// For more details, see https://www.kernel.org/doc/Documentation/filesystems/proc.txt +func parseMountInfoLine(line string) *Mount { + fields := strings.Split(line, " ") + if len(fields) < 10 { + return nil + } + + // Count the optional fields. In case new fields are appended later, + // don't simply assume that n == len(fields) - 4. + n := 6 + for fields[n] != "-" { + n++ + if n >= len(fields) { + return nil + } + } + if n+3 >= len(fields) { + return nil + } + + var mnt *Mount = &Mount{} + mnt.Path = unescapeString(fields[4]) + mnt.FilesystemType = unescapeString(fields[n+1]) + mnt.Device = unescapeString(fields[n+2]) + return mnt +} + +// loadMountInfo populates the Mount mappings by parsing /proc/self/mountinfo. +// It returns an error if the Mount mappings cannot be populated. func loadMountInfo() error { if mountsInitialized { return nil } - - // make new maps mountsByPath = make(map[string]*Mount) mountsByDevice = make(map[string][]*Mount) - // Load the mount information from mountpoints_filename - fileHandle := C.setmntent(C.mountpoints_filename, C.read_mode) - if fileHandle == nil { - return errors.Wrapf(ErrGlobalMountInfo, "could not read %q", - C.GoString(C.mountpoints_filename)) + file, err := os.Open("/proc/self/mountinfo") + if err != nil { + return err } - defer C.endmntent(fileHandle) - - for { - entry := C.getmntent(fileHandle) - // When getmntent returns nil, we have read all of the entries. - if entry == nil { - mountsInitialized = true - return nil - } - - // Create the Mount structure by converting types. - mnt := Mount{ - Path: C.GoString(entry.mnt_dir), - FilesystemType: C.GoString(entry.mnt_type), + defer file.Close() + scanner := bufio.NewScanner(file) + for scanner.Scan() { + line := scanner.Text() + mnt := parseMountInfoLine(line) + if mnt == nil { + log.Printf("ignoring invalid mountinfo line %q", line) + continue } // Skip invalid mountpoints @@ -99,22 +142,25 @@ func loadMountInfo() error { } // We can only use mountpoints that are directories for fscrypt. if !isDir(mnt.Path) { - log.Printf("mnt_dir %v: not a directory", mnt.Path) + log.Printf("ignoring mountpoint %q because it is not a directory", mnt.Path) continue } // Note this overrides the info if we have seen the mountpoint // earlier in the file. This is correct behavior because the // filesystems are listed in mount order. - mountsByPath[mnt.Path] = &mnt + mountsByPath[mnt.Path] = mnt - deviceName, err := canonicalizePath(C.GoString(entry.mnt_fsname)) + mnt.Device, err = canonicalizePath(mnt.Device) // Only use real valid devices (unlike cgroups, tmpfs, ...) - if err == nil && isDevice(deviceName) { - mnt.Device = deviceName - mountsByDevice[deviceName] = append(mountsByDevice[deviceName], &mnt) + if err == nil && isDevice(mnt.Device) { + mountsByDevice[mnt.Device] = append(mountsByDevice[mnt.Device], mnt) + } else { + mnt.Device = "" } } + mountsInitialized = true + return nil } // AllFilesystems lists all the Mounts on the current system ordered by path. |