// walkProcPid walks over all numerical (PID) /proc entries, and sees if their
// ./fd/* files are symlink to sockets. Returns a map from socket ID (inode)
// to PID. Will return an error if /proc isn't there.
func walkProcPid(buf *bytes.Buffer, walker process.Walker) (map[uint64]*Proc, error) {
var (
res = map[uint64]*Proc{}
namespaces = map[uint64]bool{} // map namespace id -> has connections
statT syscall.Stat_t
)
walker.Walk(func(p, _ process.Process) {
dirName := strconv.Itoa(p.PID)
fdBase := filepath.Join(procRoot, dirName, "fd")
// Read network namespace, and if we haven't seen it before,
// read /proc/<pid>/net/tcp
if err := fs.Lstat(filepath.Join(procRoot, dirName, "/ns/net"), &statT); err != nil {
return
}
hasConns, ok := namespaces[statT.Ino]
if !ok {
read, _ := readFile(filepath.Join(procRoot, dirName, "/net/tcp"), buf)
read6, _ := readFile(filepath.Join(procRoot, dirName, "/net/tcp6"), buf)
hasConns = read+read6 > 0
namespaces[statT.Ino] = hasConns
}
if !hasConns {
return
}
fds, err := fs.ReadDirNames(fdBase)
if err != nil {
// Process is be gone by now, or we don't have access.
return
}
var proc *Proc
for _, fd := range fds {
// Direct use of syscall.Stat() to save garbage.
err = fs.Stat(filepath.Join(fdBase, fd), &statT)
if err != nil {
continue
}
// We want sockets only.
if statT.Mode&syscall.S_IFMT != syscall.S_IFSOCK {
continue
}
if proc == nil {
proc = &Proc{
PID: uint(p.PID),
Name: p.Name,
}
}
res[statT.Ino] = proc
}
})
return res, nil
}
func (p dir) Lstat(path string, stat *syscall.Stat_t) error {
if path == "/" {
return nil
}
head, tail := split(path)
fs, ok := p.entries[head]
if !ok {
return fmt.Errorf("Not found: %s", path)
}
return fs.Lstat(tail, stat)
}