support attaching by name for platform android (#160931)

## Bug
Trying to attach to an android process by name fails:
```
(lldb) process attach -n com.android.bluetooth
error: attach failed: could not find a process named com.android.bluetooth
```

## Root Cause
PlatformAndroid does not implement the `FindProcesses` method.

As described in `include/lldb/Target/Platform.h`:
```
  // The base class Platform will take care of the host platform. Subclasses
  // will need to fill in the remote case.
  virtual uint32_t FindProcesses(const ProcessInstanceInfoMatch &match_info,
                                 ProcessInstanceInfoList &proc_infos);
```

## Fix
Implement the `FindProcesses` method in PlatformAndroid. Use adb to get
the pid of the process name on the device with the adb client connection
using `adb shell pidof <name>`.

## Reproduce
With an android device connected, run the following

Install and start lldb-server on device
```
adb push lldb-server /data/local/tmp/
adb shell chmod +x /data/local/tmp/lldb-server
adb shell /data/local/tmp/lldb-server platform  --listen 127.0.0.1:9500 --server
```

Start lldb, and run
```
platform select remote-android
platform connect connect://127.0.0.1:9500
log enable lldb platform
```

Connect to the process by name:
```
process attach -n com.android.bluetooth
```

## Test Plan
Before:
```
(lldb) process attach -n com.android.bluetooth
error: attach failed: could not find a process named com.android.bluetooth
```

After:
```
(lldb) process attach -n com.android.bluetooth
lldb             AdbClient::ResolveDeviceID Resolved device ID: 127.0.0.1
lldb             AdbClient::AdbClient(device_id='127.0.0.1') - Creating AdbClient with device ID
lldb             Connecting to ADB server at connect://127.0.0.1:5037
lldb             Connected to Android device "127.0.0.1"
lldb             Forwarding remote TCP port 38315 to local TCP port 35243
lldb             AdbClient::~AdbClient() - Destroying AdbClient for device: 127.0.0.1
lldb             gdbserver connect URL: connect://127.0.0.1:35243
lldb             AdbClient::AdbClient(device_id='127.0.0.1') - Creating AdbClient with device ID
lldb             Connecting to ADB server at connect://127.0.0.1:5037
lldb             Selecting device: 127.0.0.1
lldb             PlatformAndroid::FindProcesses found process 'com.android.bluetooth' with PID 2223
lldb             AdbClient::~AdbClient() - Destroying AdbClient for device: 127.0.0.1
llvm-worker-48   PlatformRemoteGDBServer::GetModuleSpec - got module info for (/apex/com.android.art/lib64/libc++.so:aarch64-unknown-linux-android) : file = '/apex/com.android.art/lib64/libc++.so', arch = aarch64-unknown-linux-android, uuid = 552995D0-A86D-055F-1F03-C13783A2A16C, object size = 754128
llvm-worker-9    PlatformRemoteGDBServer::GetModuleSpec - got module info for (/apex/com.android.art/lib64/liblzma.so:aarch64-unknown-linux-android) : file = '/apex/com.android.art/lib64/liblzma.so', arch = aarch64-unknown-linux-android, uuid = E51CAC98-666F-6C3F-F605-1498079542E0, object size = 179944
Process 2223 stopped
```

Author: cs01

lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp

@@ -477,6 +477,249 @@ std::string PlatformAndroid::GetRunAs() {
   }
   return run_as.str();
 }
+
+// Helper function to populate process status information from
+// /proc/[pid]/status
+void PlatformAndroid::PopulateProcessStatusInfo(
+    lldb::pid_t pid, ProcessInstanceInfo &process_info) {
+  // Read /proc/[pid]/status to get parent PID, UIDs, and GIDs
+  Status error;
+  AdbClientUP status_adb = GetAdbClient(error);
+  if (error.Fail())
+    return;
+
+  std::string status_output;
+  StreamString status_cmd;
+  status_cmd.Printf(
+      "cat /proc/%llu/status 2>/dev/null | grep -E '^(PPid|Uid|Gid):'",
+      static_cast<unsigned long long>(pid));
+  Status status_error =
+      status_adb->Shell(status_cmd.GetData(), seconds(5), &status_output);
+
+  if (status_error.Fail() || status_output.empty())
+    return;
+
+  llvm::SmallVector<llvm::StringRef, 16> lines;
+  llvm::StringRef(status_output).split(lines, '\n');
+
+  for (llvm::StringRef line : lines) {
+    line = line.trim();
+    if (line.starts_with("PPid:")) {
+      llvm::StringRef ppid_str = line.substr(5).trim();
+      lldb::pid_t ppid;
+      if (llvm::to_integer(ppid_str, ppid))
+        process_info.SetParentProcessID(ppid);
+    } else if (line.starts_with("Uid:")) {
+      llvm::SmallVector<llvm::StringRef, 4> uid_parts;
+      line.substr(4).trim().split(uid_parts, '\t', -1, false);
+      if (uid_parts.size() >= 2) {
+        uint32_t uid, euid;
+        if (llvm::to_integer(uid_parts[0].trim(), uid))
+          process_info.SetUserID(uid);
+        if (llvm::to_integer(uid_parts[1].trim(), euid))
+          process_info.SetEffectiveUserID(euid);
+      }
+    } else if (line.starts_with("Gid:")) {
+      llvm::SmallVector<llvm::StringRef, 4> gid_parts;
+      line.substr(4).trim().split(gid_parts, '\t', -1, false);
+      if (gid_parts.size() >= 2) {
+        uint32_t gid, egid;
+        if (llvm::to_integer(gid_parts[0].trim(), gid))
+          process_info.SetGroupID(gid);
+        if (llvm::to_integer(gid_parts[1].trim(), egid))
+          process_info.SetEffectiveGroupID(egid);
+      }
+    }
+  }
+}
+
+// Helper function to populate command line arguments from /proc/[pid]/cmdline
+void PlatformAndroid::PopulateProcessCommandLine(
+    lldb::pid_t pid, ProcessInstanceInfo &process_info) {
+  // Read /proc/[pid]/cmdline to get command line arguments
+  Status error;
+  AdbClientUP cmdline_adb = GetAdbClient(error);
+  if (error.Fail())
+    return;
+
+  std::string cmdline_output;
+  StreamString cmdline_cmd;
+  cmdline_cmd.Printf("cat /proc/%llu/cmdline 2>/dev/null | tr '\\000' ' '",
+                     static_cast<unsigned long long>(pid));
+  Status cmdline_error =
+      cmdline_adb->Shell(cmdline_cmd.GetData(), seconds(5), &cmdline_output);
+
+  if (cmdline_error.Fail() || cmdline_output.empty())
+    return;
+
+  cmdline_output = llvm::StringRef(cmdline_output).trim().str();
+  if (cmdline_output.empty())
+    return;
+
+  llvm::SmallVector<llvm::StringRef, 16> args;
+  llvm::StringRef(cmdline_output).split(args, ' ', -1, false);
+  if (args.empty())
+    return;
+
+  process_info.SetArg0(args[0]);
+  Args process_args;
+  for (size_t i = 1; i < args.size(); i++) {
+    if (!args[i].empty())
+      process_args.AppendArgument(args[i]);
+  }
+  process_info.SetArguments(process_args, false);
+}
+
+// Helper function to populate architecture from /proc/[pid]/exe
+void PlatformAndroid::PopulateProcessArchitecture(
+    lldb::pid_t pid, ProcessInstanceInfo &process_info) {
+  // Read /proc/[pid]/exe to get executable path for architecture detection
+  Status error;
+  AdbClientUP exe_adb = GetAdbClient(error);
+  if (error.Fail())
+    return;
+
+  std::string exe_output;
+  StreamString exe_cmd;
+  exe_cmd.Printf("readlink /proc/%llu/exe 2>/dev/null",
+                 static_cast<unsigned long long>(pid));
+  Status exe_error = exe_adb->Shell(exe_cmd.GetData(), seconds(5), &exe_output);
+
+  if (exe_error.Fail() || exe_output.empty())
+    return;
+
+  exe_output = llvm::StringRef(exe_output).trim().str();
+
+  // Determine architecture from exe path
+  ArchSpec arch;
+  if (exe_output.find("64") != std::string::npos ||
+      exe_output.find("arm64") != std::string::npos ||
+      exe_output.find("aarch64") != std::string::npos) {
+    arch.SetTriple("aarch64-unknown-linux-android");
+  } else if (exe_output.find("x86_64") != std::string::npos) {
+    arch.SetTriple("x86_64-unknown-linux-android");
+  } else if (exe_output.find("x86") != std::string::npos ||
+             exe_output.find("i686") != std::string::npos) {
+    arch.SetTriple("i686-unknown-linux-android");
+  } else {
+    // Default to armv7 for 32-bit ARM (most common on Android)
+    arch.SetTriple("armv7-unknown-linux-android");
+  }
+
+  if (arch.IsValid())
+    process_info.SetArchitecture(arch);
+}
+
+uint32_t
+PlatformAndroid::FindProcesses(const ProcessInstanceInfoMatch &match_info,
+                               ProcessInstanceInfoList &proc_infos) {
+  proc_infos.clear();
+
+  // When LLDB is running natively on an Android device (IsHost() == true),
+  // use the parent class's standard Linux /proc enumeration. IsHost() is only
+  // true when compiled for Android (#if defined(__ANDROID__)), so calling
+  // PlatformLinux methods is safe (Android is Linux-based).
+  if (IsHost())
+    return PlatformLinux::FindProcesses(match_info, proc_infos);
+
+  // Remote Android platform: implement process name lookup using 'pidof' over
+  // adb.
+
+  // LLDB stores the search name in GetExecutableFile() (even though it's
+  // actually a process name like "com.android.chrome" rather than an
+  // executable path). If no search name is provided, we can't use
+  // 'pidof', so return early with no results.
+  const ProcessInstanceInfo &match_process_info = match_info.GetProcessInfo();
+  if (!match_process_info.GetExecutableFile() ||
+      match_info.GetNameMatchType() == NameMatch::Ignore) {
+    return 0;
+  }
+
+  // Extract the process name to search for (typically an Android package name
+  // like "com.example.app" or binary name like "app_process64")
+  std::string process_name = match_process_info.GetExecutableFile().GetPath();
+  if (process_name.empty())
+    return 0;
+
+  // Use adb to find the process by name
+  Status error;
+  AdbClientUP adb(GetAdbClient(error));
+  if (error.Fail()) {
+    Log *log = GetLog(LLDBLog::Platform);
+    LLDB_LOGF(log, "PlatformAndroid::%s failed to get ADB client: %s",
+              __FUNCTION__, error.AsCString());
+    return 0;
+  }
+
+  // Use 'pidof' command to get PIDs for the process name.
+  // Quote the process name to handle special characters (spaces, etc.)
+  std::string pidof_output;
+  StreamString command;
+  command.Printf("pidof '%s'", process_name.c_str());
+  error = adb->Shell(command.GetData(), seconds(5), &pidof_output);
+
+  if (error.Fail()) {
+    Log *log = GetLog(LLDBLog::Platform);
+    LLDB_LOG(log, "PlatformAndroid::{} 'pidof {}' failed: {}", __FUNCTION__,
+             process_name.c_str(), error.AsCString());
+    return 0;
+  }
+
+  // Parse PIDs from pidof output.
+  // Note: pidof can return multiple PIDs (space-separated) if multiple
+  // instances of the same executable are running.
+  pidof_output = llvm::StringRef(pidof_output).trim().str();
+  if (pidof_output.empty()) {
+    Log *log = GetLog(LLDBLog::Platform);
+    LLDB_LOGF(log, "PlatformAndroid::%s no process found with name '%s'",
+              __FUNCTION__, process_name.c_str());
+    return 0;
+  }
+
+  // Split the output by whitespace to handle multiple PIDs
+  llvm::SmallVector<llvm::StringRef, 8> pid_strings;
+  llvm::StringRef(pidof_output).split(pid_strings, ' ', -1, false);
+
+  Log *log = GetLog(LLDBLog::Platform);
+
+  // Process each PID and gather information
+  uint32_t num_matches = 0;
+  for (llvm::StringRef pid_str : pid_strings) {
+    pid_str = pid_str.trim();
+    if (pid_str.empty())
+      continue;
+
+    lldb::pid_t pid;
+    if (!llvm::to_integer(pid_str, pid)) {
+      LLDB_LOGF(log, "PlatformAndroid::%s failed to parse PID from: '%s'",
+                __FUNCTION__, pid_str.str().c_str());
+      continue;
+    }
+
+    ProcessInstanceInfo process_info;
+    process_info.SetProcessID(pid);
+    process_info.GetExecutableFile().SetFile(process_name,
+                                             FileSpec::Style::posix);
+
+    // Populate additional process information
+    PopulateProcessStatusInfo(pid, process_info);
+    PopulateProcessCommandLine(pid, process_info);
+    PopulateProcessArchitecture(pid, process_info);
+
+    // Check if this process matches the criteria
+    if (match_info.Matches(process_info)) {
+      proc_infos.push_back(process_info);
+      num_matches++;
+
+      LLDB_LOGF(log, "PlatformAndroid::%s found process '%s' with PID %llu",
+                __FUNCTION__, process_name.c_str(),
+                static_cast<unsigned long long>(pid));
+    }
+  }
+
+  return num_matches;
+}
+
 std::unique_ptr<AdbSyncService> PlatformAndroid::GetSyncService(Status &error) {
   auto sync_service = std::make_unique<AdbSyncService>(m_device_id);
   error = sync_service->SetupSyncConnection();

lldb/source/Plugins/Platform/Android/PlatformAndroid.h

@@ -59,6 +59,9 @@ class PlatformAndroid : public platform_linux::PlatformLinux {
 
   uint32_t GetDefaultMemoryCacheLineSize() override;
 
+  uint32_t FindProcesses(const ProcessInstanceInfoMatch &match_info,
+                         ProcessInstanceInfoList &proc_infos) override;
+
 protected:
   const char *GetCacheHostname() override;
 
@@ -86,6 +89,14 @@ class PlatformAndroid : public platform_linux::PlatformLinux {
 private:
   std::string m_device_id;
   uint32_t m_sdk_version;
+
+  // Helper functions for process information gathering
+  void PopulateProcessStatusInfo(lldb::pid_t pid,
+                                 ProcessInstanceInfo &process_info);
+  void PopulateProcessCommandLine(lldb::pid_t pid,
+                                  ProcessInstanceInfo &process_info);
+  void PopulateProcessArchitecture(lldb::pid_t pid,
+                                   ProcessInstanceInfo &process_info);
 };
 
 } // namespace platform_android