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