// 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) ReadDirNames(path string) ([]string, error) {
if path == "/" {
result := []string{}
for _, v := range p.entries {
result = append(result, v.Name())
}
return result, nil
}
head, tail := split(path)
fs, ok := p.entries[head]
if !ok {
return nil, fmt.Errorf("Not found: %s", path)
}
return fs.ReadDirNames(tail)
}
// Walk walks the supplied directory (expecting it to look like /proc)
// and marshalls the files into instances of Process, which it then
// passes one-by-one to the supplied function. Walk is only made public
// so that is can be tested.
func (w *walker) Walk(f func(Process, Process)) error {
dirEntries, err := fs.ReadDirNames(w.procRoot)
if err != nil {
return err
}
for _, filename := range dirEntries {
pid, err := strconv.Atoi(filename)
if err != nil {
continue
}
ppid, threads, jiffies, rss, err := readStats(path.Join(w.procRoot, filename, "stat"))
if err != nil {
continue
}
cmdline, name := "", "(unknown)"
if cmdlineBuf, err := cachedReadFile(path.Join(w.procRoot, filename, "cmdline")); err == nil {
// like proc, treat name as the first element of command line
i := bytes.IndexByte(cmdlineBuf, '\000')
if i == -1 {
i = len(cmdlineBuf)
}
name = string(cmdlineBuf[:i])
cmdlineBuf = bytes.Replace(cmdlineBuf, []byte{'\000'}, []byte{' '}, -1)
cmdline = string(cmdlineBuf)
}
f(Process{
PID: pid,
PPID: ppid,
Name: name,
Cmdline: cmdline,
Threads: threads,
Jiffies: jiffies,
RSSBytes: rss,
}, Process{})
}
return nil
}