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
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
|
#include "nar-accessor.hh"
#include "archive.hh"
#include <map>
#include <stack>
#include <algorithm>
namespace nix {
struct NarMember
{
FSAccessor::Type type;
bool isExecutable;
/* If this is a regular file, position of the contents of this
file in the NAR. */
size_t start, size;
std::string target;
/* If this is a directory, all the children of the directory. */
std::map<std::string, NarMember> children;
};
struct NarIndexer : ParseSink, StringSource
{
NarMember root;
std::stack<NarMember*> parents;
std::string currentStart;
bool isExec = false;
NarIndexer(const std::string & nar) : StringSource(nar)
{
}
void createMember(const Path & path, NarMember member) {
size_t level = std::count(path.begin(), path.end(), '/');
while(parents.size() > level) {
parents.pop();
}
if(parents.empty()) {
root = std::move(member);
parents.push(&root);
} else {
if(parents.top()->type != FSAccessor::Type::tDirectory) {
throw Error(format("NAR file missing parent directory of path ‘%1%’") % path);
}
auto result = parents.top()->children.emplace(baseNameOf(path), std::move(member));
parents.push(&result.first->second);
}
}
void createDirectory(const Path & path) override
{
createMember(path, {FSAccessor::Type::tDirectory, false, 0, 0 });
}
void createRegularFile(const Path & path) override
{
createMember(path, {FSAccessor::Type::tRegular, false, 0, 0 });
}
void isExecutable() override
{
parents.top()->isExecutable = true;
}
void preallocateContents(unsigned long long size) override
{
currentStart = string(s, pos, 16);
assert(size <= std::numeric_limits<size_t>::max());
parents.top()->size = (size_t)size;
parents.top()->start = pos;
}
void receiveContents(unsigned char * data, unsigned int len) override
{
// Sanity check
if (!currentStart.empty()) {
assert(len < 16 || currentStart == string((char *) data, 16));
currentStart.clear();
}
}
void createSymlink(const Path & path, const string & target) override
{
createMember(path,
NarMember{FSAccessor::Type::tSymlink, false, 0, 0, target});
}
NarMember* find(const Path & path)
{
Path canon = path == "" ? "" : canonPath(path);
NarMember* current = &root;
auto end = path.end();
for(auto it = path.begin(); it != end; ) {
// because it != end, the remaining component is non-empty so we need
// a directory
if(current->type != FSAccessor::Type::tDirectory) return nullptr;
// skip slash (canonPath above ensures that this is always a slash)
assert(*it == '/');
it += 1;
// lookup current component
auto next = std::find(it, end, '/');
auto child = current->children.find(std::string(it, next));
if(child == current->children.end()) return nullptr;
current = &child->second;
it = next;
}
return current;
}
NarMember& at(const Path & path) {
auto result = find(path);
if(result == nullptr) {
throw Error(format("NAR file does not contain path ‘%1%’") % path);
}
return *result;
}
};
struct NarAccessor : public FSAccessor
{
ref<const std::string> nar;
NarIndexer indexer;
NarAccessor(ref<const std::string> nar) : nar(nar), indexer(*nar)
{
parseDump(indexer, indexer);
}
Stat stat(const Path & path) override
{
auto i = indexer.find(path);
if (i == nullptr)
return {FSAccessor::Type::tMissing, 0, false};
return {i->type, i->size, i->isExecutable};
}
StringSet readDirectory(const Path & path) override
{
auto i = indexer.at(path);
if (i.type != FSAccessor::Type::tDirectory)
throw Error(format("path ‘%1%’ inside NAR file is not a directory") % path);
StringSet res;
for(auto&& child : i.children) {
res.insert(child.first);
}
return res;
}
std::string readFile(const Path & path) override
{
auto i = indexer.at(path);
if (i.type != FSAccessor::Type::tRegular)
throw Error(format("path ‘%1%’ inside NAR file is not a regular file") % path);
return std::string(*nar, i.start, i.size);
}
std::string readLink(const Path & path) override
{
auto i = indexer.at(path);
if (i.type != FSAccessor::Type::tSymlink)
throw Error(format("path ‘%1%’ inside NAR file is not a symlink") % path);
return i.target;
}
};
ref<FSAccessor> makeNarAccessor(ref<const std::string> nar)
{
return make_ref<NarAccessor>(nar);
}
}
|
