blob: 42f93d43c15918f528d0a196bf4388d821814854 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
package system
import (
"context"
"errors"
"log"
"sync"
"git.gensokyo.uk/security/fortify/internal/fmsg"
)
const (
// User type is reverted at final launcher exit.
User = Enablement(ELen)
// Process type is unconditionally reverted on exit.
Process = Enablement(ELen + 1)
)
type Criteria struct {
*Enablements
}
func (ec *Criteria) hasType(o Op) bool {
// nil criteria: revert everything except User
if ec.Enablements == nil {
return o.Type() != User
}
return ec.Has(o.Type())
}
// Op is a reversible system operation.
type Op interface {
// Type returns Op's enablement type.
Type() Enablement
// apply the Op
apply(sys *I) error
// revert reverses the Op if criteria is met
revert(sys *I, ec *Criteria) error
Is(o Op) bool
Path() string
String() string
}
func TypeString(e Enablement) string {
switch e {
case User:
return "User"
case Process:
return "Process"
default:
return e.String()
}
}
type I struct {
uid int
ops []Op
ctx context.Context
// whether sys has been reverted
state bool
lock sync.Mutex
}
func (sys *I) UID() int {
return sys.uid
}
func (sys *I) Equal(v *I) bool {
if v == nil || sys.uid != v.uid || len(sys.ops) != len(v.ops) {
return false
}
for i, o := range sys.ops {
if !o.Is(v.ops[i]) {
return false
}
}
return true
}
func (sys *I) Commit(ctx context.Context) error {
sys.lock.Lock()
defer sys.lock.Unlock()
if sys.ctx != nil {
panic("sys instance committed twice")
}
sys.ctx = ctx
sp := New(sys.uid)
sp.ops = make([]Op, 0, len(sys.ops)) // prevent copies during commits
defer func() {
// sp is set to nil when all ops are applied
if sp != nil {
// rollback partial commit
fmsg.Verbosef("commit faulted after %d ops, rolling back partial commit", len(sp.ops))
if err := sp.Revert(&Criteria{nil}); err != nil {
log.Println("errors returned reverting partial commit:", err)
}
}
}()
for _, o := range sys.ops {
if err := o.apply(sys); err != nil {
return err
} else {
// register partial commit
sp.ops = append(sp.ops, o)
}
}
// disarm partial commit rollback
sp = nil
return nil
}
func (sys *I) Revert(ec *Criteria) error {
sys.lock.Lock()
defer sys.lock.Unlock()
if sys.state {
panic("sys instance reverted twice")
}
sys.state = true
// collect errors
errs := make([]error, len(sys.ops))
for i := range sys.ops {
errs[i] = sys.ops[len(sys.ops)-i-1].revert(sys, ec)
}
// errors.Join filters nils
return errors.Join(errs...)
}
func New(uid int) *I {
return &I{uid: uid}
}
|
