about summary refs log tree commit diff
path: root/third_party/nix/src/libstore/remote-fs-accessor.cc
blob: 819f54c161e80317c178a5badab21c0699d5094c (plain) (blame)
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
#include "remote-fs-accessor.hh"

#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>

#include "json.hh"
#include "nar-accessor.hh"

namespace nix {

RemoteFSAccessor::RemoteFSAccessor(ref<Store> store, const Path& cacheDir)
    : store(store), cacheDir(cacheDir) {
  if (cacheDir != "") {
    createDirs(cacheDir);
  }
}

Path RemoteFSAccessor::makeCacheFile(const Path& storePath,
                                     const std::string& ext) {
  assert(cacheDir != "");
  return fmt("%s/%s.%s", cacheDir, storePathToHash(storePath), ext);
}

void RemoteFSAccessor::addToCache(const Path& storePath, const std::string& nar,
                                  ref<FSAccessor> narAccessor) {
  nars.emplace(storePath, narAccessor);

  if (cacheDir != "") {
    try {
      std::ostringstream str;
      JSONPlaceholder jsonRoot(str);
      listNar(jsonRoot, narAccessor, "", true);
      writeFile(makeCacheFile(storePath, "ls"), str.str());

      /* FIXME: do this asynchronously. */
      writeFile(makeCacheFile(storePath, "nar"), nar);

    } catch (...) {
      ignoreException();
    }
  }
}

std::pair<ref<FSAccessor>, Path> RemoteFSAccessor::fetch(const Path& path_) {
  auto path = canonPath(path_);

  auto storePath = store->toStorePath(path);
  std::string restPath = std::string(path, storePath.size());

  if (!store->isValidPath(storePath)) {
    throw InvalidPath(format("path '%1%' is not a valid store path") %
                      storePath);
  }

  auto i = nars.find(storePath);
  if (i != nars.end()) {
    return {i->second, restPath};
  }

  StringSink sink;
  std::string listing;
  Path cacheFile;

  if (cacheDir != "" &&
      pathExists(cacheFile = makeCacheFile(storePath, "nar"))) {
    try {
      listing = nix::readFile(makeCacheFile(storePath, "ls"));

      auto narAccessor = makeLazyNarAccessor(
          listing, [cacheFile](uint64_t offset, uint64_t length) {
            AutoCloseFD fd = open(cacheFile.c_str(), O_RDONLY | O_CLOEXEC);
            if (!fd) {
              throw SysError("opening NAR cache file '%s'", cacheFile);
            }

            if (lseek(fd.get(), offset, SEEK_SET) != (off_t)offset) {
              throw SysError("seeking in '%s'", cacheFile);
            }

            std::string buf(length, 0);
            readFull(fd.get(), (unsigned char*)buf.data(), length);

            return buf;
          });

      nars.emplace(storePath, narAccessor);
      return {narAccessor, restPath};

    } catch (SysError&) {
    }

    try {
      *sink.s = nix::readFile(cacheFile);

      auto narAccessor = makeNarAccessor(sink.s);
      nars.emplace(storePath, narAccessor);
      return {narAccessor, restPath};

    } catch (SysError&) {
    }
  }

  store->narFromPath(storePath, sink);
  auto narAccessor = makeNarAccessor(sink.s);
  addToCache(storePath, *sink.s, narAccessor);
  return {narAccessor, restPath};
}

FSAccessor::Stat RemoteFSAccessor::stat(const Path& path) {
  auto res = fetch(path);
  return res.first->stat(res.second);
}

StringSet RemoteFSAccessor::readDirectory(const Path& path) {
  auto res = fetch(path);
  return res.first->readDirectory(res.second);
}

std::string RemoteFSAccessor::readFile(const Path& path) {
  auto res = fetch(path);
  return res.first->readFile(res.second);
}

std::string RemoteFSAccessor::readLink(const Path& path) {
  auto res = fetch(path);
  return res.first->readLink(res.second);
}

}  // namespace nix