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moby--moby/pkg/mount/mountinfo_freebsd.go
Kir Kolyshkin bb934c6aca pkg/mount: implement/use filter for mountinfo parsing
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>
2018-04-19 14:48:09 -07:00

55 lines
1.1 KiB
Go

package mount // import "github.com/docker/docker/pkg/mount"
/*
#include <sys/param.h>
#include <sys/ucred.h>
#include <sys/mount.h>
*/
import "C"
import (
"fmt"
"reflect"
"unsafe"
)
// Parse /proc/self/mountinfo because comparing Dev and ino does not work from
// bind mounts.
func parseMountTable(filter FilterFunc) ([]*Info, error) {
var rawEntries *C.struct_statfs
count := int(C.getmntinfo(&rawEntries, C.MNT_WAIT))
if count == 0 {
return nil, fmt.Errorf("Failed to call getmntinfo")
}
var entries []C.struct_statfs
header := (*reflect.SliceHeader)(unsafe.Pointer(&entries))
header.Cap = count
header.Len = count
header.Data = uintptr(unsafe.Pointer(rawEntries))
var out []*Info
for _, entry := range entries {
var mountinfo Info
var skip, stop bool
mountinfo.Mountpoint = C.GoString(&entry.f_mntonname[0])
if filter != nil {
// filter out entries we're not interested in
skip, stop = filter(p)
if skip {
continue
}
}
mountinfo.Source = C.GoString(&entry.f_mntfromname[0])
mountinfo.Fstype = C.GoString(&entry.f_fstypename[0])
out = append(out, &mountinfo)
if stop {
break
}
}
return out, nil
}