1// Copyright 2019 The Prometheus Authors
2// Licensed under the Apache License, Version 2.0 (the "License");
3// you may not use this file except in compliance with the License.
4// You may obtain a copy of the License at
5//
6// http://www.apache.org/licenses/LICENSE-2.0
7//
8// Unless required by applicable law or agreed to in writing, software
9// distributed under the License is distributed on an "AS IS" BASIS,
10// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11// See the License for the specific language governing permissions and
12// limitations under the License.
13
14package procfs
15
16import (
17	"bufio"
18	"bytes"
19	"fmt"
20	"regexp"
21
22	"github.com/prometheus/procfs/internal/util"
23)
24
25// Regexp variables
26var (
27	rPos          = regexp.MustCompile(`^pos:\s+(\d+)$`)
28	rFlags        = regexp.MustCompile(`^flags:\s+(\d+)$`)
29	rMntID        = regexp.MustCompile(`^mnt_id:\s+(\d+)$`)
30	rInotify      = regexp.MustCompile(`^inotify`)
31	rInotifyParts = regexp.MustCompile(`^inotify\s+wd:([0-9a-f]+)\s+ino:([0-9a-f]+)\s+sdev:([0-9a-f]+)(?:\s+mask:([0-9a-f]+))?`)
32)
33
34// ProcFDInfo contains represents file descriptor information.
35type ProcFDInfo struct {
36	// File descriptor
37	FD string
38	// File offset
39	Pos string
40	// File access mode and status flags
41	Flags string
42	// Mount point ID
43	MntID string
44	// List of inotify lines (structured) in the fdinfo file (kernel 3.8+ only)
45	InotifyInfos []InotifyInfo
46}
47
48// FDInfo constructor. On kernels older than 3.8, InotifyInfos will always be empty.
49func (p Proc) FDInfo(fd string) (*ProcFDInfo, error) {
50	data, err := util.ReadFileNoStat(p.path("fdinfo", fd))
51	if err != nil {
52		return nil, err
53	}
54
55	var text, pos, flags, mntid string
56	var inotify []InotifyInfo
57
58	scanner := bufio.NewScanner(bytes.NewReader(data))
59	for scanner.Scan() {
60		text = scanner.Text()
61		if rPos.MatchString(text) {
62			pos = rPos.FindStringSubmatch(text)[1]
63		} else if rFlags.MatchString(text) {
64			flags = rFlags.FindStringSubmatch(text)[1]
65		} else if rMntID.MatchString(text) {
66			mntid = rMntID.FindStringSubmatch(text)[1]
67		} else if rInotify.MatchString(text) {
68			newInotify, err := parseInotifyInfo(text)
69			if err != nil {
70				return nil, err
71			}
72			inotify = append(inotify, *newInotify)
73		}
74	}
75
76	i := &ProcFDInfo{
77		FD:           fd,
78		Pos:          pos,
79		Flags:        flags,
80		MntID:        mntid,
81		InotifyInfos: inotify,
82	}
83
84	return i, nil
85}
86
87// InotifyInfo represents a single inotify line in the fdinfo file.
88type InotifyInfo struct {
89	// Watch descriptor number
90	WD string
91	// Inode number
92	Ino string
93	// Device ID
94	Sdev string
95	// Mask of events being monitored
96	Mask string
97}
98
99// InotifyInfo constructor. Only available on kernel 3.8+.
100func parseInotifyInfo(line string) (*InotifyInfo, error) {
101	m := rInotifyParts.FindStringSubmatch(line)
102	if len(m) >= 4 {
103		var mask string
104		if len(m) == 5 {
105			mask = m[4]
106		}
107		i := &InotifyInfo{
108			WD:   m[1],
109			Ino:  m[2],
110			Sdev: m[3],
111			Mask: mask,
112		}
113		return i, nil
114	}
115	return nil, fmt.Errorf("invalid inode entry: %q", line)
116}
117
118// ProcFDInfos represents a list of ProcFDInfo structs.
119type ProcFDInfos []ProcFDInfo
120
121func (p ProcFDInfos) Len() int           { return len(p) }
122func (p ProcFDInfos) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
123func (p ProcFDInfos) Less(i, j int) bool { return p[i].FD < p[j].FD }
124
125// InotifyWatchLen returns the total number of inotify watches
126func (p ProcFDInfos) InotifyWatchLen() (int, error) {
127	length := 0
128	for _, f := range p {
129		length += len(f.InotifyInfos)
130	}
131
132	return length, nil
133}
134