Kir Kolyshkin
a97e7a41c8
Functions `GetMounts()` and `parseMountTable()` return all the entries as read and parsed from /proc/self/mountinfo. In many cases the caller is only interested only one or a few entries, not all of them. One good example is `Mounted()` function, which looks for a specific entry only. Another example is `RecursiveUnmount()` which is only interested in mount under a specific path. This commit adds `filter` argument to `GetMounts()` to implement two things: 1. filter out entries a caller is not interested in 2. stop processing if a caller is found what it wanted `nil` can be passed to get a backward-compatible behavior, i.e. return all the entries. A few filters are implemented: - `PrefixFilter`: filters out all entries not under `prefix` - `SingleEntryFilter`: looks for a specific entry Finally, `Mounted()` is modified to use `SingleEntryFilter()`, and `RecursiveUnmount()` is using `PrefixFilter()`. Unit tests are added to check filters are working. [v2: ditch NoFilter, use nil] [v3: ditch GetMountsFiltered()] [v4: add unit test for filters] [v5: switch to gotestyourself] Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com> Upstream-commit: bb934c6aca3e77541dd4fd51b9ab2706294dadda Component: engine
105 lines
2.8 KiB
Go
105 lines
2.8 KiB
Go
package mount // import "github.com/docker/docker/pkg/mount"
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import (
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"bufio"
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"fmt"
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"io"
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"os"
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"strings"
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)
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const (
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/* 36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
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(1)(2)(3) (4) (5) (6) (7) (8) (9) (10) (11)
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(1) mount ID: unique identifier of the mount (may be reused after umount)
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(2) parent ID: ID of parent (or of self for the top of the mount tree)
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(3) major:minor: value of st_dev for files on filesystem
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(4) root: root of the mount within the filesystem
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(5) mount point: mount point relative to the process's root
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(6) mount options: per mount options
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(7) optional fields: zero or more fields of the form "tag[:value]"
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(8) separator: marks the end of the optional fields
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(9) filesystem type: name of filesystem of the form "type[.subtype]"
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(10) mount source: filesystem specific information or "none"
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(11) super options: per super block options*/
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mountinfoFormat = "%d %d %d:%d %s %s %s %s"
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)
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// Parse /proc/self/mountinfo because comparing Dev and ino does not work from
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// bind mounts
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func parseMountTable(filter FilterFunc) ([]*Info, error) {
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f, err := os.Open("/proc/self/mountinfo")
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if err != nil {
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return nil, err
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}
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defer f.Close()
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return parseInfoFile(f, filter)
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}
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func parseInfoFile(r io.Reader, filter FilterFunc) ([]*Info, error) {
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var (
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s = bufio.NewScanner(r)
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out = []*Info{}
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)
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for s.Scan() {
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if err := s.Err(); err != nil {
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return nil, err
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}
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var (
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p = &Info{}
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text = s.Text()
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optionalFields string
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skip, stop bool
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)
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if _, err := fmt.Sscanf(text, mountinfoFormat,
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&p.ID, &p.Parent, &p.Major, &p.Minor,
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&p.Root, &p.Mountpoint, &p.Opts, &optionalFields); err != nil {
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return nil, fmt.Errorf("Scanning '%s' failed: %s", text, err)
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}
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if filter != nil {
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// filter out entries we're not interested in
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skip, stop = filter(p)
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if skip {
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continue
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}
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}
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// Safe as mountinfo encodes mountpoints with spaces as \040.
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index := strings.Index(text, " - ")
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postSeparatorFields := strings.Fields(text[index+3:])
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if len(postSeparatorFields) < 3 {
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return nil, fmt.Errorf("Error found less than 3 fields post '-' in %q", text)
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}
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if optionalFields != "-" {
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p.Optional = optionalFields
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}
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p.Fstype = postSeparatorFields[0]
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p.Source = postSeparatorFields[1]
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p.VfsOpts = strings.Join(postSeparatorFields[2:], " ")
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out = append(out, p)
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if stop {
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break
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}
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}
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return out, nil
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}
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// PidMountInfo collects the mounts for a specific process ID. If the process
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// ID is unknown, it is better to use `GetMounts` which will inspect
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// "/proc/self/mountinfo" instead.
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func PidMountInfo(pid int) ([]*Info, error) {
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f, err := os.Open(fmt.Sprintf("/proc/%d/mountinfo", pid))
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if err != nil {
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return nil, err
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}
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defer f.Close()
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return parseInfoFile(f, nil)
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}
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