1 //===-- PlatformQemuUser.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 
9 #include "Plugins/Platform/QemuUser/PlatformQemuUser.h"
10 #include "Plugins/Process/gdb-remote/ProcessGDBRemote.h"
11 #include "lldb/Core/PluginManager.h"
12 #include "lldb/Host/FileSystem.h"
13 #include "lldb/Host/ProcessLaunchInfo.h"
14 #include "lldb/Interpreter/OptionValueProperties.h"
15 #include "lldb/Target/Process.h"
16 #include "lldb/Target/Target.h"
17 #include "lldb/Utility/Listener.h"
18 #include "lldb/Utility/Log.h"
19 
20 using namespace lldb;
21 using namespace lldb_private;
22 
23 LLDB_PLUGIN_DEFINE(PlatformQemuUser)
24 
25 #define LLDB_PROPERTIES_platformqemuuser
26 #include "PlatformQemuUserProperties.inc"
27 
28 enum {
29 #define LLDB_PROPERTIES_platformqemuuser
30 #include "PlatformQemuUserPropertiesEnum.inc"
31 };
32 
33 class PluginProperties : public Properties {
34 public:
35   PluginProperties() {
36     m_collection_sp = std::make_shared<OptionValueProperties>(
37         ConstString(PlatformQemuUser::GetPluginNameStatic()));
38     m_collection_sp->Initialize(g_platformqemuuser_properties);
39   }
40 
41   llvm::StringRef GetArchitecture() {
42     return m_collection_sp->GetPropertyAtIndexAsString(
43         nullptr, ePropertyArchitecture, "");
44   }
45 
46   FileSpec GetEmulatorPath() {
47     return m_collection_sp->GetPropertyAtIndexAsFileSpec(nullptr,
48                                                          ePropertyEmulatorPath);
49   }
50 
51   Args GetEmulatorArgs() {
52     Args result;
53     m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, ePropertyEmulatorArgs,
54                                               result);
55     return result;
56   }
57 
58   Environment GetEmulatorEnvVars() {
59     Args args;
60     m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, ePropertyEmulatorEnvVars,
61                                               args);
62     return Environment(args);
63   }
64 
65   Environment GetTargetEnvVars() {
66     Args args;
67     m_collection_sp->GetPropertyAtIndexAsArgs(nullptr, ePropertyTargetEnvVars,
68                                               args);
69     return Environment(args);
70   }
71 };
72 
73 static PluginProperties &GetGlobalProperties() {
74   static PluginProperties g_settings;
75   return g_settings;
76 }
77 
78 llvm::StringRef PlatformQemuUser::GetPluginDescriptionStatic() {
79   return "Platform for debugging binaries under user mode qemu";
80 }
81 
82 void PlatformQemuUser::Initialize() {
83   PluginManager::RegisterPlugin(
84       GetPluginNameStatic(), GetPluginDescriptionStatic(),
85       PlatformQemuUser::CreateInstance, PlatformQemuUser::DebuggerInitialize);
86 }
87 
88 void PlatformQemuUser::Terminate() {
89   PluginManager::UnregisterPlugin(PlatformQemuUser::CreateInstance);
90 }
91 
92 void PlatformQemuUser::DebuggerInitialize(Debugger &debugger) {
93   if (!PluginManager::GetSettingForPlatformPlugin(
94           debugger, ConstString(GetPluginNameStatic()))) {
95     PluginManager::CreateSettingForPlatformPlugin(
96         debugger, GetGlobalProperties().GetValueProperties(),
97         ConstString("Properties for the qemu-user platform plugin."),
98         /*is_global_property=*/true);
99   }
100 }
101 
102 PlatformSP PlatformQemuUser::CreateInstance(bool force, const ArchSpec *arch) {
103   if (force)
104     return PlatformSP(new PlatformQemuUser());
105   return nullptr;
106 }
107 
108 std::vector<ArchSpec> PlatformQemuUser::GetSupportedArchitectures() {
109   llvm::Triple triple = HostInfo::GetArchitecture().GetTriple();
110   triple.setEnvironment(llvm::Triple::UnknownEnvironment);
111   triple.setArchName(GetGlobalProperties().GetArchitecture());
112   if (triple.getArch() != llvm::Triple::UnknownArch)
113     return {ArchSpec(triple)};
114   return {};
115 }
116 
117 static auto get_arg_range(const Args &args) {
118   return llvm::make_range(args.GetArgumentArrayRef().begin(),
119                           args.GetArgumentArrayRef().end());
120 }
121 
122 // Returns the emulator environment which result in the desired environment
123 // being presented to the emulated process. We want to be careful about
124 // preserving the host environment, as it may contain entries (LD_LIBRARY_PATH,
125 // for example) needed for the operation of the emulator itself.
126 static Environment ComputeLaunchEnvironment(Environment target,
127                                             Environment host) {
128   std::vector<std::string> set_env;
129   for (const auto &KV : target) {
130     // If the host value differs from the target (or is unset), then set it
131     // through QEMU_SET_ENV. Identical entries will be forwarded automatically.
132     auto host_it = host.find(KV.first());
133     if (host_it == host.end() || host_it->second != KV.second)
134       set_env.push_back(Environment::compose(KV));
135   }
136   llvm::sort(set_env);
137 
138   std::vector<llvm::StringRef> unset_env;
139   for (const auto &KV : host) {
140     // If the target is missing some host entries, then unset them through
141     // QEMU_UNSET_ENV.
142     if (target.count(KV.first()) == 0)
143       unset_env.push_back(KV.first());
144   }
145   llvm::sort(unset_env);
146 
147   // The actual QEMU_(UN)SET_ENV variables should not be forwarded to the
148   // target.
149   if (!set_env.empty()) {
150     host["QEMU_SET_ENV"] = llvm::join(set_env, ",");
151     unset_env.push_back("QEMU_SET_ENV");
152   }
153   if (!unset_env.empty()) {
154     unset_env.push_back("QEMU_UNSET_ENV");
155     host["QEMU_UNSET_ENV"] = llvm::join(unset_env, ",");
156   }
157   return host;
158 }
159 
160 lldb::ProcessSP PlatformQemuUser::DebugProcess(ProcessLaunchInfo &launch_info,
161                                                Debugger &debugger,
162                                                Target &target, Status &error) {
163   Log *log = GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PLATFORM);
164 
165   FileSpec qemu = GetGlobalProperties().GetEmulatorPath();
166   if (!qemu)
167     qemu.SetPath(("qemu-" + GetGlobalProperties().GetArchitecture()).str());
168   FileSystem::Instance().ResolveExecutableLocation(qemu);
169 
170   llvm::SmallString<0> socket_model, socket_path;
171   HostInfo::GetProcessTempDir().GetPath(socket_model);
172   llvm::sys::path::append(socket_model, "qemu-%%%%%%%%.socket");
173   do {
174     llvm::sys::fs::createUniquePath(socket_model, socket_path, false);
175   } while (FileSystem::Instance().Exists(socket_path));
176 
177   Args args({qemu.GetPath(), "-g", socket_path});
178   if (!launch_info.GetArg0().empty()) {
179     args.AppendArgument("-0");
180     args.AppendArgument(launch_info.GetArg0());
181   }
182   args.AppendArguments(GetGlobalProperties().GetEmulatorArgs());
183   args.AppendArgument("--");
184   args.AppendArgument(launch_info.GetExecutableFile().GetPath());
185   for (size_t i = 1; i < launch_info.GetArguments().size(); ++i)
186     args.AppendArgument(launch_info.GetArguments()[i].ref());
187 
188   LLDB_LOG(log, "{0} -> {1}", get_arg_range(launch_info.GetArguments()),
189            get_arg_range(args));
190 
191   launch_info.SetArguments(args, true);
192 
193   Environment emulator_env = Host::GetEnvironment();
194   if (ConstString sysroot = GetSDKRootDirectory())
195     emulator_env["QEMU_LD_PREFIX"] = sysroot.GetStringRef().str();
196   for (const auto &KV : GetGlobalProperties().GetEmulatorEnvVars())
197     emulator_env[KV.first()] = KV.second;
198   launch_info.GetEnvironment() = ComputeLaunchEnvironment(
199       std::move(launch_info.GetEnvironment()), std::move(emulator_env));
200 
201   launch_info.SetLaunchInSeparateProcessGroup(true);
202   launch_info.GetFlags().Clear(eLaunchFlagDebug);
203   launch_info.SetMonitorProcessCallback(ProcessLaunchInfo::NoOpMonitorCallback,
204                                         false);
205 
206   // This is automatically done for host platform in
207   // Target::FinalizeFileActions, but we're not a host platform.
208   llvm::Error Err = launch_info.SetUpPtyRedirection();
209   LLDB_LOG_ERROR(log, std::move(Err), "SetUpPtyRedirection failed: {0}");
210 
211   error = Host::LaunchProcess(launch_info);
212   if (error.Fail())
213     return nullptr;
214 
215   ProcessSP process_sp = target.CreateProcess(
216       launch_info.GetListener(),
217       process_gdb_remote::ProcessGDBRemote::GetPluginNameStatic(), nullptr,
218       true);
219 
220   ListenerSP listener_sp =
221       Listener::MakeListener("lldb.platform_qemu_user.debugprocess");
222   launch_info.SetHijackListener(listener_sp);
223   Process::ProcessEventHijacker hijacker(*process_sp, listener_sp);
224 
225   error = process_sp->ConnectRemote(("unix-connect://" + socket_path).str());
226   if (error.Fail())
227     return nullptr;
228 
229   if (launch_info.GetPTY().GetPrimaryFileDescriptor() !=
230       PseudoTerminal::invalid_fd)
231     process_sp->SetSTDIOFileDescriptor(
232         launch_info.GetPTY().ReleasePrimaryFileDescriptor());
233 
234   process_sp->WaitForProcessToStop(llvm::None, nullptr, false, listener_sp);
235   return process_sp;
236 }
237 
238 Environment PlatformQemuUser::GetEnvironment() {
239   Environment env = Host::GetEnvironment();
240   for (const auto &KV : GetGlobalProperties().GetTargetEnvVars())
241     env[KV.first()] = KV.second;
242   return env;
243 }
244