LLDB  mainline
ModuleCache.cpp
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1 //===-- ModuleCache.cpp ---------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 
11 #include "lldb/Core/Module.h"
12 #include "lldb/Core/ModuleList.h"
13 #include "lldb/Core/ModuleSpec.h"
14 #include "lldb/Host/File.h"
15 #include "lldb/Host/LockFile.h"
16 #include "lldb/Utility/LLDBLog.h"
17 #include "lldb/Utility/Log.h"
18 #include "llvm/Support/FileSystem.h"
19 #include "llvm/Support/FileUtilities.h"
20 
21 #include <cassert>
22 
23 #include <cstdio>
24 
25 using namespace lldb;
26 using namespace lldb_private;
27 
28 namespace {
29 
30 const char *kModulesSubdir = ".cache";
31 const char *kLockDirName = ".lock";
32 const char *kTempFileName = ".temp";
33 const char *kTempSymFileName = ".symtemp";
34 const char *kSymFileExtension = ".sym";
35 const char *kFSIllegalChars = "\\/:*?\"<>|";
36 
37 std::string GetEscapedHostname(const char *hostname) {
38  if (hostname == nullptr)
39  hostname = "unknown";
40  std::string result(hostname);
41  size_t size = result.size();
42  for (size_t i = 0; i < size; ++i) {
43  if ((result[i] >= 1 && result[i] <= 31) ||
44  strchr(kFSIllegalChars, result[i]) != nullptr)
45  result[i] = '_';
46  }
47  return result;
48 }
49 
50 class ModuleLock {
51 private:
52  FileUP m_file_up;
53  std::unique_ptr<lldb_private::LockFile> m_lock;
54  FileSpec m_file_spec;
55 
56 public:
57  ModuleLock(const FileSpec &root_dir_spec, const UUID &uuid, Status &error);
58  void Delete();
59 };
60 
61 static FileSpec JoinPath(const FileSpec &path1, const char *path2) {
62  FileSpec result_spec(path1);
63  result_spec.AppendPathComponent(path2);
64  return result_spec;
65 }
66 
67 static Status MakeDirectory(const FileSpec &dir_path) {
68  namespace fs = llvm::sys::fs;
69 
70  return fs::create_directories(dir_path.GetPath(), true, fs::perms::owner_all);
71 }
72 
73 FileSpec GetModuleDirectory(const FileSpec &root_dir_spec, const UUID &uuid) {
74  const auto modules_dir_spec = JoinPath(root_dir_spec, kModulesSubdir);
75  return JoinPath(modules_dir_spec, uuid.GetAsString().c_str());
76 }
77 
78 FileSpec GetSymbolFileSpec(const FileSpec &module_file_spec) {
79  return FileSpec(module_file_spec.GetPath() + kSymFileExtension);
80 }
81 
82 void DeleteExistingModule(const FileSpec &root_dir_spec,
83  const FileSpec &sysroot_module_path_spec) {
84  Log *log = GetLog(LLDBLog::Modules);
85  UUID module_uuid;
86  {
87  auto module_sp =
88  std::make_shared<Module>(ModuleSpec(sysroot_module_path_spec));
89  module_uuid = module_sp->GetUUID();
90  }
91 
92  if (!module_uuid.IsValid())
93  return;
94 
95  Status error;
96  ModuleLock lock(root_dir_spec, module_uuid, error);
97  if (error.Fail()) {
98  LLDB_LOGF(log, "Failed to lock module %s: %s",
99  module_uuid.GetAsString().c_str(), error.AsCString());
100  }
101 
102  namespace fs = llvm::sys::fs;
103  fs::file_status st;
104  if (status(sysroot_module_path_spec.GetPath(), st))
105  return;
106 
107  if (st.getLinkCount() > 2) // module is referred by other hosts.
108  return;
109 
110  const auto module_spec_dir = GetModuleDirectory(root_dir_spec, module_uuid);
111  llvm::sys::fs::remove_directories(module_spec_dir.GetPath());
112  lock.Delete();
113 }
114 
115 void DecrementRefExistingModule(const FileSpec &root_dir_spec,
116  const FileSpec &sysroot_module_path_spec) {
117  // Remove $platform/.cache/$uuid folder if nobody else references it.
118  DeleteExistingModule(root_dir_spec, sysroot_module_path_spec);
119 
120  // Remove sysroot link.
121  llvm::sys::fs::remove(sysroot_module_path_spec.GetPath());
122 
123  FileSpec symfile_spec = GetSymbolFileSpec(sysroot_module_path_spec);
124  llvm::sys::fs::remove(symfile_spec.GetPath());
125 }
126 
127 Status CreateHostSysRootModuleLink(const FileSpec &root_dir_spec,
128  const char *hostname,
129  const FileSpec &platform_module_spec,
130  const FileSpec &local_module_spec,
131  bool delete_existing) {
132  const auto sysroot_module_path_spec =
133  JoinPath(JoinPath(root_dir_spec, hostname),
134  platform_module_spec.GetPath().c_str());
135  if (FileSystem::Instance().Exists(sysroot_module_path_spec)) {
136  if (!delete_existing)
137  return Status();
138 
139  DecrementRefExistingModule(root_dir_spec, sysroot_module_path_spec);
140  }
141 
142  const auto error = MakeDirectory(
143  FileSpec(sysroot_module_path_spec.GetDirectory().AsCString()));
144  if (error.Fail())
145  return error;
146 
147  return llvm::sys::fs::create_hard_link(local_module_spec.GetPath(),
148  sysroot_module_path_spec.GetPath());
149 }
150 
151 } // namespace
152 
153 ModuleLock::ModuleLock(const FileSpec &root_dir_spec, const UUID &uuid,
154  Status &error) {
155  const auto lock_dir_spec = JoinPath(root_dir_spec, kLockDirName);
156  error = MakeDirectory(lock_dir_spec);
157  if (error.Fail())
158  return;
159 
160  m_file_spec = JoinPath(lock_dir_spec, uuid.GetAsString().c_str());
161 
162  auto file = FileSystem::Instance().Open(
163  m_file_spec, File::eOpenOptionWriteOnly | File::eOpenOptionCanCreate |
164  File::eOpenOptionCloseOnExec);
165  if (file)
166  m_file_up = std::move(file.get());
167  else {
168  m_file_up.reset();
169  error = Status(file.takeError());
170  return;
171  }
172 
173  m_lock = std::make_unique<lldb_private::LockFile>(m_file_up->GetDescriptor());
174  error = m_lock->WriteLock(0, 1);
175  if (error.Fail())
176  error.SetErrorStringWithFormat("Failed to lock file: %s",
177  error.AsCString());
178 }
179 
180 void ModuleLock::Delete() {
181  if (!m_file_up)
182  return;
183 
184  m_file_up->Close();
185  m_file_up.reset();
186  llvm::sys::fs::remove(m_file_spec.GetPath());
187 }
188 
189 /////////////////////////////////////////////////////////////////////////
190 
191 Status ModuleCache::Put(const FileSpec &root_dir_spec, const char *hostname,
192  const ModuleSpec &module_spec, const FileSpec &tmp_file,
193  const FileSpec &target_file) {
194  const auto module_spec_dir =
195  GetModuleDirectory(root_dir_spec, module_spec.GetUUID());
196  const auto module_file_path =
197  JoinPath(module_spec_dir, target_file.GetFilename().AsCString());
198 
199  const auto tmp_file_path = tmp_file.GetPath();
200  const auto err_code =
201  llvm::sys::fs::rename(tmp_file_path, module_file_path.GetPath());
202  if (err_code)
203  return Status("Failed to rename file %s to %s: %s", tmp_file_path.c_str(),
204  module_file_path.GetPath().c_str(),
205  err_code.message().c_str());
206 
207  const auto error = CreateHostSysRootModuleLink(
208  root_dir_spec, hostname, target_file, module_file_path, true);
209  if (error.Fail())
210  return Status("Failed to create link to %s: %s",
211  module_file_path.GetPath().c_str(), error.AsCString());
212  return Status();
213 }
214 
215 Status ModuleCache::Get(const FileSpec &root_dir_spec, const char *hostname,
216  const ModuleSpec &module_spec,
217  ModuleSP &cached_module_sp, bool *did_create_ptr) {
218  const auto find_it =
219  m_loaded_modules.find(module_spec.GetUUID().GetAsString());
220  if (find_it != m_loaded_modules.end()) {
221  cached_module_sp = (*find_it).second.lock();
222  if (cached_module_sp)
223  return Status();
224  m_loaded_modules.erase(find_it);
225  }
226 
227  const auto module_spec_dir =
228  GetModuleDirectory(root_dir_spec, module_spec.GetUUID());
229  const auto module_file_path = JoinPath(
230  module_spec_dir, module_spec.GetFileSpec().GetFilename().AsCString());
231 
232  if (!FileSystem::Instance().Exists(module_file_path))
233  return Status("Module %s not found", module_file_path.GetPath().c_str());
234  if (FileSystem::Instance().GetByteSize(module_file_path) !=
235  module_spec.GetObjectSize())
236  return Status("Module %s has invalid file size",
237  module_file_path.GetPath().c_str());
238 
239  // We may have already cached module but downloaded from an another host - in
240  // this case let's create a link to it.
241  auto error = CreateHostSysRootModuleLink(root_dir_spec, hostname,
242  module_spec.GetFileSpec(),
243  module_file_path, false);
244  if (error.Fail())
245  return Status("Failed to create link to %s: %s",
246  module_file_path.GetPath().c_str(), error.AsCString());
247 
248  auto cached_module_spec(module_spec);
249  cached_module_spec.GetUUID().Clear(); // Clear UUID since it may contain md5
250  // content hash instead of real UUID.
251  cached_module_spec.GetFileSpec() = module_file_path;
252  cached_module_spec.GetPlatformFileSpec() = module_spec.GetFileSpec();
253 
254  error = ModuleList::GetSharedModule(cached_module_spec, cached_module_sp,
255  nullptr, nullptr, did_create_ptr, false);
256  if (error.Fail())
257  return error;
258 
259  FileSpec symfile_spec = GetSymbolFileSpec(cached_module_sp->GetFileSpec());
260  if (FileSystem::Instance().Exists(symfile_spec))
261  cached_module_sp->SetSymbolFileFileSpec(symfile_spec);
262 
263  m_loaded_modules.insert(
264  std::make_pair(module_spec.GetUUID().GetAsString(), cached_module_sp));
265 
266  return Status();
267 }
268 
269 Status ModuleCache::GetAndPut(const FileSpec &root_dir_spec,
270  const char *hostname,
271  const ModuleSpec &module_spec,
272  const ModuleDownloader &module_downloader,
273  const SymfileDownloader &symfile_downloader,
274  lldb::ModuleSP &cached_module_sp,
275  bool *did_create_ptr) {
276  const auto module_spec_dir =
277  GetModuleDirectory(root_dir_spec, module_spec.GetUUID());
278  auto error = MakeDirectory(module_spec_dir);
279  if (error.Fail())
280  return error;
281 
282  ModuleLock lock(root_dir_spec, module_spec.GetUUID(), error);
283  if (error.Fail())
284  return Status("Failed to lock module %s: %s",
285  module_spec.GetUUID().GetAsString().c_str(),
286  error.AsCString());
287 
288  const auto escaped_hostname(GetEscapedHostname(hostname));
289  // Check local cache for a module.
290  error = Get(root_dir_spec, escaped_hostname.c_str(), module_spec,
291  cached_module_sp, did_create_ptr);
292  if (error.Success())
293  return error;
294 
295  const auto tmp_download_file_spec = JoinPath(module_spec_dir, kTempFileName);
296  error = module_downloader(module_spec, tmp_download_file_spec);
297  llvm::FileRemover tmp_file_remover(tmp_download_file_spec.GetPath());
298  if (error.Fail())
299  return Status("Failed to download module: %s", error.AsCString());
300 
301  // Put downloaded file into local module cache.
302  error = Put(root_dir_spec, escaped_hostname.c_str(), module_spec,
303  tmp_download_file_spec, module_spec.GetFileSpec());
304  if (error.Fail())
305  return Status("Failed to put module into cache: %s", error.AsCString());
306 
307  tmp_file_remover.releaseFile();
308  error = Get(root_dir_spec, escaped_hostname.c_str(), module_spec,
309  cached_module_sp, did_create_ptr);
310  if (error.Fail())
311  return error;
312 
313  // Fetching a symbol file for the module
314  const auto tmp_download_sym_file_spec =
315  JoinPath(module_spec_dir, kTempSymFileName);
316  error = symfile_downloader(cached_module_sp, tmp_download_sym_file_spec);
317  llvm::FileRemover tmp_symfile_remover(tmp_download_sym_file_spec.GetPath());
318  if (error.Fail())
319  // Failed to download a symfile but fetching the module was successful. The
320  // module might contain the necessary symbols and the debugging is also
321  // possible without a symfile.
322  return Status();
323 
324  error = Put(root_dir_spec, escaped_hostname.c_str(), module_spec,
325  tmp_download_sym_file_spec,
326  GetSymbolFileSpec(module_spec.GetFileSpec()));
327  if (error.Fail())
328  return Status("Failed to put symbol file into cache: %s",
329  error.AsCString());
330 
331  tmp_symfile_remover.releaseFile();
332 
333  FileSpec symfile_spec = GetSymbolFileSpec(cached_module_sp->GetFileSpec());
334  cached_module_sp->SetSymbolFileFileSpec(symfile_spec);
335  return Status();
336 }
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