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@@ -5,15 +5,19 @@ import (
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"fmt"
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"io"
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"os"
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+ "runtime"
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"strconv"
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"strings"
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+ "sync"
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+
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+ "golang.org/x/sys/unix"
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)
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// GetMountsFromReader retrieves a list of mounts from the
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// reader provided, with an optional filter applied (use nil
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// for no filter). This can be useful in tests or benchmarks
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// that provide fake mountinfo data, or when a source other
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-// than /proc/self/mountinfo needs to be read from.
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+// than /proc/thread-self/mountinfo needs to be read from.
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//
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// This function is Linux-specific.
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func GetMountsFromReader(r io.Reader, filter FilterFunc) ([]*Info, error) {
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@@ -127,8 +131,40 @@ func GetMountsFromReader(r io.Reader, filter FilterFunc) ([]*Info, error) {
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return out, nil
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}
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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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+var (
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+ haveProcThreadSelf bool
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+ haveProcThreadSelfOnce sync.Once
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+)
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+
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+func parseMountTable(filter FilterFunc) (_ []*Info, err error) {
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+ haveProcThreadSelfOnce.Do(func() {
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+ _, err := os.Stat("/proc/thread-self/mountinfo")
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+ haveProcThreadSelf = err == nil
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+ })
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+
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+ // We need to lock ourselves to the current OS thread in order to make sure
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+ // that the thread referenced by /proc/thread-self stays alive until we
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+ // finish parsing the file.
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+ runtime.LockOSThread()
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+ defer runtime.UnlockOSThread()
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+
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+ var f *os.File
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+ if haveProcThreadSelf {
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+ f, err = os.Open("/proc/thread-self/mountinfo")
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+ } else {
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+ // On pre-3.17 kernels (such as CentOS 7), we don't have
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+ // /proc/thread-self/ so we need to manually construct
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+ // /proc/self/task/<tid>/ as a fallback.
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+ f, err = os.Open("/proc/self/task/" + strconv.Itoa(unix.Gettid()) + "/mountinfo")
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+ if os.IsNotExist(err) {
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+ // If /proc/self/task/... failed, it means that our active pid
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+ // namespace doesn't match the pid namespace of the /proc mount. In
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+ // this case we just have to make do with /proc/self, since there
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+ // is no other way of figuring out our tid in a parent pid
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+ // namespace on pre-3.17 kernels.
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+ f, err = os.Open("/proc/self/mountinfo")
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+ }
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+ }
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if err != nil {
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return nil, err
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}
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@@ -158,10 +194,10 @@ func PidMountInfo(pid int) ([]*Info, error) {
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// A few specific characters in mountinfo path entries (root and mountpoint)
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// are escaped using a backslash followed by a character's ascii code in octal.
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//
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-// space -- as \040
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-// tab (aka \t) -- as \011
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-// newline (aka \n) -- as \012
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-// backslash (aka \\) -- as \134
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+// space -- as \040
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+// tab (aka \t) -- as \011
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+// newline (aka \n) -- as \012
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+// backslash (aka \\) -- as \134
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//
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// This function converts path from mountinfo back, i.e. it unescapes the above sequences.
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func unescape(path string) (string, error) {
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Sebastiaan van Stijn