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
|
// Copyright 2023 Google LLC.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// Package lockedcallbacks provides locking per-key.
package lockedcallbacks
import (
"errors"
"io"
"sync"
"text/template"
)
// ErrStateKeyNotFound indicates the requested key was not found in the map of states
var ErrStateKeyNotFound error = errors.New("Unlock requested for an unknown state")
// StatesMap wraps a map of Mstate. Each key locks separately.
type StatesMap struct {
maplock sync.Mutex // locks the States map
States map[any]*Mstate // contains states for each template
}
// Mstate is used to represent entries of StatesMap
// each entry (Mstate) holds a callback. A mutex is protecting changes to the callback
// The key and statesmap attributes are used to provide self-cleaning of the entries once a state
// does not need to be maintained.
type Mstate struct {
statesmap *StatesMap // points back to StatesMap, so we can synchronize removing this entry when cnt==0
statelock sync.Mutex // is an entry-specific lock
cnt int // references to the state
key any // indicates the key in the parent states map
Callback func(string) string // points to the callback to protect
AllowFlagsCallback func(string) string // points to the allowflags callback to protect
}
// New returns an initialized StatesMap.
func New() *StatesMap {
return &StatesMap{States: make(map[any]*Mstate)}
}
// Lock acquires a state corresponding to this key.
func (m *StatesMap) lock(key any) *Mstate {
// read or create entry for this key atomically
m.maplock.Lock()
ent, ok := m.States[key]
if !ok {
ent = &Mstate{statesmap: m, key: key}
m.States[key] = ent
}
ent.cnt++
m.maplock.Unlock()
ent.statelock.Lock()
return ent
}
// Unlock releases the lock for this entry.
func (ms *Mstate) unlock() error {
m := ms.statesmap
m.maplock.Lock()
defer m.maplock.Unlock()
ent, ok := m.States[ms.key]
if !ok {
return ErrStateKeyNotFound
}
ent.cnt--
if ent.cnt < 1 {
ent.statesmap = nil
delete(m.States, ms.key)
}
ent.statelock.Unlock()
return nil
}
// BuildTextTemplateRemediationFunc creates a virtual method calling the template's callback.
func (m *StatesMap) BuildTextTemplateRemediationFunc(safeTmplUUID string, wrapperFunc func(any, func(string) string) any) func(any) any {
remediationFunc := func(data any) any {
m.maplock.Lock()
defer m.maplock.Unlock()
tmplState, ok := m.States[safeTmplUUID]
if !ok {
return nil
}
cb := tmplState.Callback
return wrapperFunc(data, cb)
}
return remediationFunc
}
// BuildAllowFlagsCallbackFunc creates a virtual method calling the template's allowFlags callback.
func (m *StatesMap) BuildAllowFlagsCallbackFunc(safeTmplUUID string, wrapperFunc func(any, func(string) string) any) func(data any) any {
allowFlagsCallbackFunc := func(data any) any {
m.maplock.Lock()
defer m.maplock.Unlock()
tmplState, ok := m.States[safeTmplUUID]
if !ok {
return nil
}
allowFlagsCb := tmplState.AllowFlagsCallback
return wrapperFunc(data, allowFlagsCb)
}
return allowFlagsCallbackFunc
}
// SetAndExecuteWithCallback hides implementation details of the StatesMap by taking a template and
// a callback to set the proper callback and execute the template.
func (m *StatesMap) SetAndExecuteWithCallback(tmpl *template.Template, safeTmplUUID string, cb func(string) string, result io.Writer, data any) error {
tmplState := m.lock(safeTmplUUID)
tmplState.Callback = cb
err := tmpl.Execute(result, data)
if err != nil {
return err
}
return tmplState.unlock()
}
// SetAndExecuteWithShCallback hides implementation details of the StatesMap by taking a template
// and both callbacks to set the proper callback and execute the template.
func (m *StatesMap) SetAndExecuteWithShCallback(tmpl *template.Template, safeTmplUUID string, cb func(string) string, allowFlagsCb func(string) string, result io.Writer, data any) error {
tmplState := m.lock(safeTmplUUID)
tmplState.Callback = cb
tmplState.AllowFlagsCallback = allowFlagsCb
err := tmpl.Execute(result, data)
if err != nil {
return err
}
return tmplState.unlock()
}
|
