Lshal: support commands.

Support the following commands:
  lshal list
  lshal list -itrpc
  lshal help
  lshal help list
  lshal list -h
  lshal list --help

Test: run these commands
Bug: 37725279
Change-Id: I970fbc8d250d43f57e92f783229e0645d7e8df4e
diff --git a/cmds/lshal/Lshal.cpp b/cmds/lshal/Lshal.cpp
index 2fc3715..43108b7 100644
--- a/cmds/lshal/Lshal.cpp
+++ b/cmds/lshal/Lshal.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016 The Android Open Source Project
+ * Copyright (C) 2017 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -16,379 +16,108 @@
 
 #include "Lshal.h"
 
-#include <getopt.h>
+#include <set>
+#include <string>
 
-#include <fstream>
-#include <iomanip>
-#include <iostream>
-#include <map>
-#include <sstream>
-#include <regex>
-
-#include <android-base/logging.h>
-#include <android-base/parseint.h>
-#include <android/hidl/manager/1.0/IServiceManager.h>
-#include <hidl/ServiceManagement.h>
-#include <hidl-util/FQName.h>
-#include <private/android_filesystem_config.h>
-#include <sys/stat.h>
-#include <vintf/HalManifest.h>
-#include <vintf/parse_xml.h>
-
+#include "ListCommand.h"
 #include "PipeRelay.h"
-#include "Timeout.h"
-
-using ::android::hardware::hidl_string;
-using ::android::hidl::manager::V1_0::IServiceManager;
 
 namespace android {
 namespace lshal {
 
-template <typename A>
-std::string join(const A &components, const std::string &separator) {
-    std::stringstream out;
-    bool first = true;
-    for (const auto &component : components) {
-        if (!first) {
-            out << separator;
-        }
-        out << component;
+using ::android::hidl::manager::V1_0::IServiceManager;
 
-        first = false;
+Lshal::Lshal() {
+}
+
+void Lshal::usage(const std::string &command) const {
+    static const std::string helpSummary =
+            "lshal: List and debug HALs.\n"
+            "\n"
+            "commands:\n"
+            "    help            Print help message\n"
+            "    list            list HALs\n"
+            "    debug           debug a specified HAL\n"
+            "\n"
+            "If no command is specified, `list` is the default.\n";
+
+    static const std::string list =
+            "list:\n"
+            "    lshal\n"
+            "    lshal list\n"
+            "        List all hals with default ordering and columns (`lshal list -ipc`)\n"
+            "    lshal list [-h|--help]\n"
+            "        -h, --help: Print help message for list (`lshal help list`)\n"
+            "    lshal [list] [--interface|-i] [--transport|-t] [-r|--arch]\n"
+            "            [--pid|-p] [--address|-a] [--clients|-c] [--cmdline|-m]\n"
+            "            [--sort={interface|i|pid|p}] [--init-vintf[=<output file>]]\n"
+            "            [--debug|-d[=<output file>]]\n"
+            "        -i, --interface: print the interface name column\n"
+            "        -n, --instance: print the instance name column\n"
+            "        -t, --transport: print the transport mode column\n"
+            "        -r, --arch: print if the HAL is in 64-bit or 32-bit\n"
+            "        -p, --pid: print the server PID, or server cmdline if -m is set\n"
+            "        -a, --address: print the server object address column\n"
+            "        -c, --clients: print the client PIDs, or client cmdlines if -m is set\n"
+            "        -m, --cmdline: print cmdline instead of PIDs\n"
+            "        -d[=<output file>], --debug[=<output file>]: emit debug info from \n"
+            "                IBase::debug with empty options\n"
+            "        --sort=i, --sort=interface: sort by interface name\n"
+            "        --sort=p, --sort=pid: sort by server pid\n"
+            "        --init-vintf=<output file>: form a skeleton HAL manifest to specified\n"
+            "                      file, or stdout if no file specified.\n";
+
+    static const std::string debug =
+            "debug:\n"
+            "    lshal debug <interface> [options [options [...]]] \n"
+            "        Print debug information of a specified interface.\n"
+            "        <inteface>: Format is `android.hardware.foo@1.0::IFoo/default`.\n"
+            "            If instance name is missing `default` is used.\n"
+            "        options: space separated options to IBase::debug.\n";
+
+    static const std::string help =
+            "help:\n"
+            "    lshal -h\n"
+            "    lshal --help\n"
+            "    lshal help\n"
+            "        Print this help message\n"
+            "    lshal help list\n"
+            "        Print help message for list\n"
+            "    lshal help debug\n"
+            "        Print help message for debug\n";
+
+    if (command == "list") {
+        mErr << list;
+        return;
     }
-    return out.str();
-}
-
-static std::string toHexString(uint64_t t) {
-    std::ostringstream os;
-    os << std::hex << std::setfill('0') << std::setw(16) << t;
-    return os.str();
-}
-
-template<typename String>
-static std::pair<String, String> splitFirst(const String &s, char c) {
-    const char *pos = strchr(s.c_str(), c);
-    if (pos == nullptr) {
-        return {s, {}};
-    }
-    return {String(s.c_str(), pos - s.c_str()), String(pos + 1)};
-}
-
-static std::vector<std::string> split(const std::string &s, char c) {
-    std::vector<std::string> components{};
-    size_t startPos = 0;
-    size_t matchPos;
-    while ((matchPos = s.find(c, startPos)) != std::string::npos) {
-        components.push_back(s.substr(startPos, matchPos - startPos));
-        startPos = matchPos + 1;
+    if (command == "debug") {
+        mErr << debug;
+        return;
     }
 
-    if (startPos <= s.length()) {
-        components.push_back(s.substr(startPos));
-    }
-    return components;
-}
-
-static void replaceAll(std::string *s, char from, char to) {
-    for (size_t i = 0; i < s->size(); ++i) {
-        if (s->at(i) == from) {
-            s->at(i) = to;
-        }
-    }
-}
-
-std::string getCmdline(pid_t pid) {
-    std::ifstream ifs("/proc/" + std::to_string(pid) + "/cmdline");
-    std::string cmdline;
-    if (!ifs.is_open()) {
-        return "";
-    }
-    ifs >> cmdline;
-    return cmdline;
-}
-
-const std::string &Lshal::getCmdline(pid_t pid) {
-    auto pair = mCmdlines.find(pid);
-    if (pair != mCmdlines.end()) {
-        return pair->second;
-    }
-    mCmdlines[pid] = ::android::lshal::getCmdline(pid);
-    return mCmdlines[pid];
-}
-
-void Lshal::removeDeadProcesses(Pids *pids) {
-    static const pid_t myPid = getpid();
-    std::remove_if(pids->begin(), pids->end(), [this](auto pid) {
-        return pid == myPid || this->getCmdline(pid).empty();
-    });
-}
-
-bool Lshal::getReferencedPids(
-        pid_t serverPid, std::map<uint64_t, Pids> *objects) const {
-
-    std::ifstream ifs("/d/binder/proc/" + std::to_string(serverPid));
-    if (!ifs.is_open()) {
-        return false;
-    }
-
-    static const std::regex prefix("^\\s*node \\d+:\\s+u([0-9a-f]+)\\s+c([0-9a-f]+)\\s+");
-
-    std::string line;
-    std::smatch match;
-    while(getline(ifs, line)) {
-        if (!std::regex_search(line, match, prefix)) {
-            // the line doesn't start with the correct prefix
-            continue;
-        }
-        std::string ptrString = "0x" + match.str(2); // use number after c
-        uint64_t ptr;
-        if (!::android::base::ParseUint(ptrString.c_str(), &ptr)) {
-            // Should not reach here, but just be tolerant.
-            mErr << "Could not parse number " << ptrString << std::endl;
-            continue;
-        }
-        const std::string proc = " proc ";
-        auto pos = line.rfind(proc);
-        if (pos != std::string::npos) {
-            for (const std::string &pidStr : split(line.substr(pos + proc.size()), ' ')) {
-                int32_t pid;
-                if (!::android::base::ParseInt(pidStr, &pid)) {
-                    mErr << "Could not parse number " << pidStr << std::endl;
-                    continue;
-                }
-                (*objects)[ptr].push_back(pid);
-            }
-        }
-    }
-    return true;
-}
-
-// Must process hwbinder services first, then passthrough services.
-void Lshal::forEachTable(const std::function<void(Table &)> &f) {
-    f(mServicesTable);
-    f(mPassthroughRefTable);
-    f(mImplementationsTable);
-}
-void Lshal::forEachTable(const std::function<void(const Table &)> &f) const {
-    f(mServicesTable);
-    f(mPassthroughRefTable);
-    f(mImplementationsTable);
-}
-
-void Lshal::postprocess() {
-    forEachTable([this](Table &table) {
-        if (mSortColumn) {
-            std::sort(table.begin(), table.end(), mSortColumn);
-        }
-        for (TableEntry &entry : table) {
-            entry.serverCmdline = getCmdline(entry.serverPid);
-            removeDeadProcesses(&entry.clientPids);
-            for (auto pid : entry.clientPids) {
-                entry.clientCmdlines.push_back(this->getCmdline(pid));
-            }
-        }
-    });
-    // use a double for loop here because lshal doesn't care about efficiency.
-    for (TableEntry &packageEntry : mImplementationsTable) {
-        std::string packageName = packageEntry.interfaceName;
-        FQName fqPackageName{packageName.substr(0, packageName.find("::"))};
-        if (!fqPackageName.isValid()) {
-            continue;
-        }
-        for (TableEntry &interfaceEntry : mPassthroughRefTable) {
-            if (interfaceEntry.arch != ARCH_UNKNOWN) {
-                continue;
-            }
-            FQName interfaceName{splitFirst(interfaceEntry.interfaceName, '/').first};
-            if (!interfaceName.isValid()) {
-                continue;
-            }
-            if (interfaceName.getPackageAndVersion() == fqPackageName) {
-                interfaceEntry.arch = packageEntry.arch;
-            }
-        }
-    }
-}
-
-void Lshal::printLine(
-        const std::string &interfaceName,
-        const std::string &transport,
-        const std::string &arch,
-        const std::string &server,
-        const std::string &serverCmdline,
-        const std::string &address, const std::string &clients,
-        const std::string &clientCmdlines) const {
-    if (mSelectedColumns & ENABLE_INTERFACE_NAME)
-        mOut << std::setw(80) << interfaceName << "\t";
-    if (mSelectedColumns & ENABLE_TRANSPORT)
-        mOut << std::setw(10) << transport << "\t";
-    if (mSelectedColumns & ENABLE_ARCH)
-        mOut << std::setw(5) << arch << "\t";
-    if (mSelectedColumns & ENABLE_SERVER_PID) {
-        if (mEnableCmdlines) {
-            mOut << std::setw(15) << serverCmdline << "\t";
-        } else {
-            mOut << std::setw(5)  << server << "\t";
-        }
-    }
-    if (mSelectedColumns & ENABLE_SERVER_ADDR)
-        mOut << std::setw(16) << address << "\t";
-    if (mSelectedColumns & ENABLE_CLIENT_PIDS) {
-        if (mEnableCmdlines) {
-            mOut << std::setw(0)  << clientCmdlines;
-        } else {
-            mOut << std::setw(0)  << clients;
-        }
-    }
-    mOut << std::endl;
-}
-
-void Lshal::dumpVintf() const {
-    mOut << "<!-- " << std::endl
-         << "    This is a skeleton device manifest. Notes: " << std::endl
-         << "    1. android.hidl.*, android.frameworks.*, android.system.* are not included." << std::endl
-         << "    2. If a HAL is supported in both hwbinder and passthrough transport, " << std::endl
-         << "       only hwbinder is shown." << std::endl
-         << "    3. It is likely that HALs in passthrough transport does not have" << std::endl
-         << "       <interface> declared; users will have to write them by hand." << std::endl
-         << "    4. sepolicy version is set to 0.0. It is recommended that the entry" << std::endl
-         << "       is removed from the manifest file and written by assemble_vintf" << std::endl
-         << "       at build time." << std::endl
-         << "-->" << std::endl;
-
-    vintf::HalManifest manifest;
-    forEachTable([this, &manifest] (const Table &table) {
-        for (const TableEntry &entry : table) {
-
-            std::string fqInstanceName = entry.interfaceName;
-
-            if (&table == &mImplementationsTable) {
-                // Quick hack to work around *'s
-                replaceAll(&fqInstanceName, '*', 'D');
-            }
-            auto splittedFqInstanceName = splitFirst(fqInstanceName, '/');
-            FQName fqName(splittedFqInstanceName.first);
-            if (!fqName.isValid()) {
-                mErr << "Warning: '" << splittedFqInstanceName.first
-                     << "' is not a valid FQName." << std::endl;
-                continue;
-            }
-            // Strip out system libs.
-            if (fqName.inPackage("android.hidl") ||
-                fqName.inPackage("android.frameworks") ||
-                fqName.inPackage("android.system")) {
-                continue;
-            }
-            std::string interfaceName =
-                    &table == &mImplementationsTable ? "" : fqName.name();
-            std::string instanceName =
-                    &table == &mImplementationsTable ? "" : splittedFqInstanceName.second;
-
-            vintf::Version version{fqName.getPackageMajorVersion(),
-                                   fqName.getPackageMinorVersion()};
-            vintf::Transport transport;
-            vintf::Arch arch;
-            if (entry.transport == "hwbinder") {
-                transport = vintf::Transport::HWBINDER;
-                arch = vintf::Arch::ARCH_EMPTY;
-            } else if (entry.transport == "passthrough") {
-                transport = vintf::Transport::PASSTHROUGH;
-                switch (entry.arch) {
-                    case lshal::ARCH32:
-                        arch = vintf::Arch::ARCH_32;    break;
-                    case lshal::ARCH64:
-                        arch = vintf::Arch::ARCH_64;    break;
-                    case lshal::ARCH_BOTH:
-                        arch = vintf::Arch::ARCH_32_64; break;
-                    case lshal::ARCH_UNKNOWN: // fallthrough
-                    default:
-                        mErr << "Warning: '" << fqName.package()
-                             << "' doesn't have bitness info, assuming 32+64." << std::endl;
-                        arch = vintf::Arch::ARCH_32_64;
-                }
-            } else {
-                mErr << "Warning: '" << entry.transport << "' is not a valid transport." << std::endl;
-                continue;
-            }
-
-            bool done = false;
-            for (vintf::ManifestHal *hal : manifest.getHals(fqName.package())) {
-                if (hal->transport() != transport) {
-                    if (transport != vintf::Transport::PASSTHROUGH) {
-                        mErr << "Fatal: should not reach here. Generated result may be wrong."
-                             << std::endl;
-                    }
-                    done = true;
-                    break;
-                }
-                if (hal->hasVersion(version)) {
-                    if (&table != &mImplementationsTable) {
-                        hal->interfaces[interfaceName].name = interfaceName;
-                        hal->interfaces[interfaceName].instances.insert(instanceName);
-                    }
-                    done = true;
-                    break;
-                }
-            }
-            if (done) {
-                continue; // to next TableEntry
-            }
-            decltype(vintf::ManifestHal::interfaces) interfaces;
-            if (&table != &mImplementationsTable) {
-                interfaces[interfaceName].name = interfaceName;
-                interfaces[interfaceName].instances.insert(instanceName);
-            }
-            if (!manifest.add(vintf::ManifestHal{
-                    .format = vintf::HalFormat::HIDL,
-                    .name = fqName.package(),
-                    .versions = {version},
-                    .transportArch = {transport, arch},
-                    .interfaces = interfaces})) {
-                mErr << "Warning: cannot add hal '" << fqInstanceName << "'" << std::endl;
-            }
-        }
-    });
-    mOut << vintf::gHalManifestConverter(manifest);
-}
-
-static const std::string &getArchString(Architecture arch) {
-    static const std::string sStr64 = "64";
-    static const std::string sStr32 = "32";
-    static const std::string sStrBoth = "32+64";
-    static const std::string sStrUnknown = "";
-    switch (arch) {
-        case ARCH64:
-            return sStr64;
-        case ARCH32:
-            return sStr32;
-        case ARCH_BOTH:
-            return sStrBoth;
-        case ARCH_UNKNOWN: // fall through
-        default:
-            return sStrUnknown;
-    }
-}
-
-static Architecture fromBaseArchitecture(::android::hidl::base::V1_0::DebugInfo::Architecture a) {
-    switch (a) {
-        case ::android::hidl::base::V1_0::DebugInfo::Architecture::IS_64BIT:
-            return ARCH64;
-        case ::android::hidl::base::V1_0::DebugInfo::Architecture::IS_32BIT:
-            return ARCH32;
-        case ::android::hidl::base::V1_0::DebugInfo::Architecture::UNKNOWN: // fallthrough
-        default:
-            return ARCH_UNKNOWN;
-    }
+    mErr << helpSummary << "\n" << list << "\n" << debug << "\n" << help;
 }
 
 // A unique_ptr type using a custom deleter function.
 template<typename T>
 using deleted_unique_ptr = std::unique_ptr<T, std::function<void(T *)> >;
 
+static hardware::hidl_vec<hardware::hidl_string> convert(const std::vector<std::string> &v) {
+    hardware::hidl_vec<hardware::hidl_string> hv;
+    hv.resize(v.size());
+    for (size_t i = 0; i < v.size(); ++i) {
+        hv[i].setToExternal(v[i].c_str(), v[i].size());
+    }
+    return hv;
+}
+
+// static
 void Lshal::emitDebugInfo(
         const sp<IServiceManager> &serviceManager,
         const std::string &interfaceName,
-        const std::string &instanceName) const {
+        const std::string &instanceName,
+        const std::vector<std::string> &options,
+        std::ostream &out) {
     using android::hidl::base::V1_0::IBase;
 
     hardware::Return<sp<IBase>> retBase =
@@ -396,16 +125,14 @@
 
     sp<IBase> base;
     if (!retBase.isOk() || (base = retBase) == nullptr) {
-        // There's a small race, where a service instantiated while collecting
-        // the list of services has by now terminated, so this isn't anything
-        // to be concerned about.
+        mErr << interfaceName << "/" << instanceName << " does not exist." << std::endl;
         return;
     }
 
-    PipeRelay relay(mOut.buf());
+    PipeRelay relay(out);
 
     if (relay.initCheck() != OK) {
-        LOG(ERROR) << "PipeRelay::initCheck() FAILED w/ " << relay.initCheck();
+        mErr << "PipeRelay::initCheck() FAILED w/ " << relay.initCheck() << std::endl;
         return;
     }
 
@@ -415,8 +142,7 @@
 
     fdHandle->data[0] = relay.fd();
 
-    hardware::hidl_vec<hardware::hidl_string> options;
-    hardware::Return<void> ret = base->debug(fdHandle.get(), options);
+    hardware::Return<void> ret = base->debug(fdHandle.get(), convert(options));
 
     if (!ret.isOk()) {
         LOG(ERROR)
@@ -427,396 +153,56 @@
     }
 }
 
-void Lshal::dumpTable() {
-    mServicesTable.description =
-            "All binderized services (registered services through hwservicemanager)";
-    mPassthroughRefTable.description =
-            "All interfaces that getService() has ever return as a passthrough interface;\n"
-            "PIDs / processes shown below might be inaccurate because the process\n"
-            "might have relinquished the interface or might have died.\n"
-            "The Server / Server CMD column can be ignored.\n"
-            "The Clients / Clients CMD column shows all process that have ever dlopen'ed \n"
-            "the library and successfully fetched the passthrough implementation.";
-    mImplementationsTable.description =
-            "All available passthrough implementations (all -impl.so files)";
-    forEachTable([this] (const Table &table) {
-        mOut << table.description << std::endl;
-        mOut << std::left;
-        printLine("Interface", "Transport", "Arch", "Server", "Server CMD",
-                  "PTR", "Clients", "Clients CMD");
-
-        // We're only interested in dumping debug info for already
-        // instantiated services. There's little value in dumping the
-        // debug info for a service we create on the fly, so we only operate
-        // on the "mServicesTable".
-        sp<IServiceManager> serviceManager;
-        if (mEmitDebugInfo && &table == &mServicesTable) {
-            serviceManager = ::android::hardware::defaultServiceManager();
-        }
-
-        for (const auto &entry : table) {
-            printLine(entry.interfaceName,
-                    entry.transport,
-                    getArchString(entry.arch),
-                    entry.serverPid == NO_PID ? "N/A" : std::to_string(entry.serverPid),
-                    entry.serverCmdline,
-                    entry.serverObjectAddress == NO_PTR ? "N/A" : toHexString(entry.serverObjectAddress),
-                    join(entry.clientPids, " "),
-                    join(entry.clientCmdlines, ";"));
-
-            if (serviceManager != nullptr) {
-                auto pair = splitFirst(entry.interfaceName, '/');
-                emitDebugInfo(serviceManager, pair.first, pair.second);
-            }
-        }
-        mOut << std::endl;
-    });
-
-}
-
-void Lshal::dump() {
-    if (mVintf) {
-        dumpVintf();
-        if (!!mFileOutput) {
-            mFileOutput.buf().close();
-            delete &mFileOutput.buf();
-            mFileOutput = nullptr;
-        }
-        mOut = std::cout;
-    } else {
-        dumpTable();
-    }
-}
-
-void Lshal::putEntry(TableEntrySource source, TableEntry &&entry) {
-    Table *table = nullptr;
-    switch (source) {
-        case HWSERVICEMANAGER_LIST :
-            table = &mServicesTable; break;
-        case PTSERVICEMANAGER_REG_CLIENT :
-            table = &mPassthroughRefTable; break;
-        case LIST_DLLIB :
-            table = &mImplementationsTable; break;
-        default:
-            mErr << "Error: Unknown source of entry " << source << std::endl;
-    }
-    if (table) {
-        table->entries.push_back(std::forward<TableEntry>(entry));
-    }
-}
-
-Status Lshal::fetchAllLibraries(const sp<IServiceManager> &manager) {
-    using namespace ::android::hardware;
-    using namespace ::android::hidl::manager::V1_0;
-    using namespace ::android::hidl::base::V1_0;
-    auto ret = timeoutIPC(manager, &IServiceManager::debugDump, [&] (const auto &infos) {
-        std::map<std::string, TableEntry> entries;
-        for (const auto &info : infos) {
-            std::string interfaceName = std::string{info.interfaceName.c_str()} + "/" +
-                    std::string{info.instanceName.c_str()};
-            entries.emplace(interfaceName, TableEntry{
-                .interfaceName = interfaceName,
-                .transport = "passthrough",
-                .serverPid = NO_PID,
-                .serverObjectAddress = NO_PTR,
-                .clientPids = {},
-                .arch = ARCH_UNKNOWN
-            }).first->second.arch |= fromBaseArchitecture(info.arch);
-        }
-        for (auto &&pair : entries) {
-            putEntry(LIST_DLLIB, std::move(pair.second));
-        }
-    });
-    if (!ret.isOk()) {
-        mErr << "Error: Failed to call list on getPassthroughServiceManager(): "
-             << ret.description() << std::endl;
-        return DUMP_ALL_LIBS_ERROR;
-    }
-    return OK;
-}
-
-Status Lshal::fetchPassthrough(const sp<IServiceManager> &manager) {
-    using namespace ::android::hardware;
-    using namespace ::android::hardware::details;
-    using namespace ::android::hidl::manager::V1_0;
-    using namespace ::android::hidl::base::V1_0;
-    auto ret = timeoutIPC(manager, &IServiceManager::debugDump, [&] (const auto &infos) {
-        for (const auto &info : infos) {
-            if (info.clientPids.size() <= 0) {
-                continue;
-            }
-            putEntry(PTSERVICEMANAGER_REG_CLIENT, {
-                .interfaceName =
-                        std::string{info.interfaceName.c_str()} + "/" +
-                        std::string{info.instanceName.c_str()},
-                .transport = "passthrough",
-                .serverPid = info.clientPids.size() == 1 ? info.clientPids[0] : NO_PID,
-                .serverObjectAddress = NO_PTR,
-                .clientPids = info.clientPids,
-                .arch = fromBaseArchitecture(info.arch)
-            });
-        }
-    });
-    if (!ret.isOk()) {
-        mErr << "Error: Failed to call debugDump on defaultServiceManager(): "
-             << ret.description() << std::endl;
-        return DUMP_PASSTHROUGH_ERROR;
-    }
-    return OK;
-}
-
-Status Lshal::fetchBinderized(const sp<IServiceManager> &manager) {
-    using namespace ::std;
-    using namespace ::android::hardware;
-    using namespace ::android::hidl::manager::V1_0;
-    using namespace ::android::hidl::base::V1_0;
-    const std::string mode = "hwbinder";
-
-    hidl_vec<hidl_string> fqInstanceNames;
-    // copying out for timeoutIPC
-    auto listRet = timeoutIPC(manager, &IServiceManager::list, [&] (const auto &names) {
-        fqInstanceNames = names;
-    });
-    if (!listRet.isOk()) {
-        mErr << "Error: Failed to list services for " << mode << ": "
-             << listRet.description() << std::endl;
-        return DUMP_BINDERIZED_ERROR;
-    }
-
-    Status status = OK;
-    // server pid, .ptr value of binder object, child pids
-    std::map<std::string, DebugInfo> allDebugInfos;
-    std::map<pid_t, std::map<uint64_t, Pids>> allPids;
-    for (const auto &fqInstanceName : fqInstanceNames) {
-        const auto pair = splitFirst(fqInstanceName, '/');
-        const auto &serviceName = pair.first;
-        const auto &instanceName = pair.second;
-        auto getRet = timeoutIPC(manager, &IServiceManager::get, serviceName, instanceName);
-        if (!getRet.isOk()) {
-            mErr << "Warning: Skipping \"" << fqInstanceName << "\": "
-                 << "cannot be fetched from service manager:"
-                 << getRet.description() << std::endl;
-            status |= DUMP_BINDERIZED_ERROR;
-            continue;
-        }
-        sp<IBase> service = getRet;
-        if (service == nullptr) {
-            mErr << "Warning: Skipping \"" << fqInstanceName << "\": "
-                 << "cannot be fetched from service manager (null)";
-            status |= DUMP_BINDERIZED_ERROR;
-            continue;
-        }
-        auto debugRet = timeoutIPC(service, &IBase::getDebugInfo, [&] (const auto &debugInfo) {
-            allDebugInfos[fqInstanceName] = debugInfo;
-            if (debugInfo.pid >= 0) {
-                allPids[static_cast<pid_t>(debugInfo.pid)].clear();
-            }
-        });
-        if (!debugRet.isOk()) {
-            mErr << "Warning: Skipping \"" << fqInstanceName << "\": "
-                 << "debugging information cannot be retrieved:"
-                 << debugRet.description() << std::endl;
-            status |= DUMP_BINDERIZED_ERROR;
-        }
-    }
-    for (auto &pair : allPids) {
-        pid_t serverPid = pair.first;
-        if (!getReferencedPids(serverPid, &allPids[serverPid])) {
-            mErr << "Warning: no information for PID " << serverPid
-                      << ", are you root?" << std::endl;
-            status |= DUMP_BINDERIZED_ERROR;
-        }
-    }
-    for (const auto &fqInstanceName : fqInstanceNames) {
-        auto it = allDebugInfos.find(fqInstanceName);
-        if (it == allDebugInfos.end()) {
-            putEntry(HWSERVICEMANAGER_LIST, {
-                .interfaceName = fqInstanceName,
-                .transport = mode,
-                .serverPid = NO_PID,
-                .serverObjectAddress = NO_PTR,
-                .clientPids = {},
-                .arch = ARCH_UNKNOWN
-            });
-            continue;
-        }
-        const DebugInfo &info = it->second;
-        putEntry(HWSERVICEMANAGER_LIST, {
-            .interfaceName = fqInstanceName,
-            .transport = mode,
-            .serverPid = info.pid,
-            .serverObjectAddress = info.ptr,
-            .clientPids = info.pid == NO_PID || info.ptr == NO_PTR
-                    ? Pids{} : allPids[info.pid][info.ptr],
-            .arch = fromBaseArchitecture(info.arch),
-        });
-    }
-    return status;
-}
-
-Status Lshal::fetch() {
-    Status status = OK;
-    auto bManager = ::android::hardware::defaultServiceManager();
-    if (bManager == nullptr) {
-        mErr << "Failed to get defaultServiceManager()!" << std::endl;
-        status |= NO_BINDERIZED_MANAGER;
-    } else {
-        status |= fetchBinderized(bManager);
-        // Passthrough PIDs are registered to the binderized manager as well.
-        status |= fetchPassthrough(bManager);
-    }
-
-    auto pManager = ::android::hardware::getPassthroughServiceManager();
-    if (pManager == nullptr) {
-        mErr << "Failed to get getPassthroughServiceManager()!" << std::endl;
-        status |= NO_PASSTHROUGH_MANAGER;
-    } else {
-        status |= fetchAllLibraries(pManager);
-    }
-    return status;
-}
-
-void Lshal::usage() const {
-    mErr
-        << "usage: lshal" << std::endl
-        << "           Dump all hals with default ordering and columns [-ipc]." << std::endl
-        << "       lshal [--interface|-i] [--transport|-t] [-r|--arch]" << std::endl
-        << "             [--pid|-p] [--address|-a] [--clients|-c] [--cmdline|-m]" << std::endl
-        << "             [--sort={interface|i|pid|p}] [--init-vintf[=path]]" << std::endl
-        << "           -i, --interface: print the interface name column" << std::endl
-        << "           -n, --instance: print the instance name column" << std::endl
-        << "           -t, --transport: print the transport mode column" << std::endl
-        << "           -r, --arch: print if the HAL is in 64-bit or 32-bit" << std::endl
-        << "           -p, --pid: print the server PID, or server cmdline if -m is set" << std::endl
-        << "           -a, --address: print the server object address column" << std::endl
-        << "           -c, --clients: print the client PIDs, or client cmdlines if -m is set"
-                                                                              << std::endl
-        << "           -m, --cmdline: print cmdline instead of PIDs" << std::endl
-        << "           -d, --debug: emit debug info from IBase::debug" << std::endl
-        << "           --sort=i, --sort=interface: sort by interface name" << std::endl
-        << "           --sort=p, --sort=pid: sort by server pid" << std::endl
-        << "           --init-vintf=path: form a skeleton HAL manifest to specified file " << std::endl
-        << "                         (stdout if no file specified)" << std::endl
-        << "       lshal [-h|--help]" << std::endl
-        << "           -h, --help: show this help information." << std::endl;
-}
-
-Status Lshal::parseArgs(int argc, char **argv) {
-    static struct option longOptions[] = {
-        // long options with short alternatives
-        {"help",      no_argument,       0, 'h' },
-        {"interface", no_argument,       0, 'i' },
-        {"transport", no_argument,       0, 't' },
-        {"arch",      no_argument,       0, 'r' },
-        {"pid",       no_argument,       0, 'p' },
-        {"address",   no_argument,       0, 'a' },
-        {"clients",   no_argument,       0, 'c' },
-        {"cmdline",   no_argument,       0, 'm' },
-        {"debug",     optional_argument, 0, 'd' },
-
-        // long options without short alternatives
-        {"sort",      required_argument, 0, 's' },
-        {"init-vintf",optional_argument, 0, 'v' },
-        { 0,          0,                 0,  0  }
-    };
-
-    int optionIndex;
-    int c;
+Status Lshal::parseArgs(const Arg &arg) {
+    static std::set<std::string> sAllCommands{"list", "debug", "help"};
     optind = 1;
-    for (;;) {
-        // using getopt_long in case we want to add other options in the future
-        c = getopt_long(argc, argv, "hitrpacmd", longOptions, &optionIndex);
-        if (c == -1) {
-            break;
-        }
-        switch (c) {
-        case 's': {
-            if (strcmp(optarg, "interface") == 0 || strcmp(optarg, "i") == 0) {
-                mSortColumn = TableEntry::sortByInterfaceName;
-            } else if (strcmp(optarg, "pid") == 0 || strcmp(optarg, "p") == 0) {
-                mSortColumn = TableEntry::sortByServerPid;
-            } else {
-                mErr << "Unrecognized sorting column: " << optarg << std::endl;
-                usage();
-                return USAGE;
-            }
-            break;
-        }
-        case 'v': {
-            if (optarg) {
-                mFileOutput = new std::ofstream{optarg};
-                mOut = mFileOutput;
-                if (!mFileOutput.buf().is_open()) {
-                    mErr << "Could not open file '" << optarg << "'." << std::endl;
-                    return IO_ERROR;
-                }
-            }
-            mVintf = true;
-        }
-        case 'i': {
-            mSelectedColumns |= ENABLE_INTERFACE_NAME;
-            break;
-        }
-        case 't': {
-            mSelectedColumns |= ENABLE_TRANSPORT;
-            break;
-        }
-        case 'r': {
-            mSelectedColumns |= ENABLE_ARCH;
-            break;
-        }
-        case 'p': {
-            mSelectedColumns |= ENABLE_SERVER_PID;
-            break;
-        }
-        case 'a': {
-            mSelectedColumns |= ENABLE_SERVER_ADDR;
-            break;
-        }
-        case 'c': {
-            mSelectedColumns |= ENABLE_CLIENT_PIDS;
-            break;
-        }
-        case 'm': {
-            mEnableCmdlines = true;
-            break;
-        }
-        case 'd': {
-            mEmitDebugInfo = true;
-
-            if (optarg) {
-                mFileOutput = new std::ofstream{optarg};
-                mOut = mFileOutput;
-                if (!mFileOutput.buf().is_open()) {
-                    mErr << "Could not open file '" << optarg << "'." << std::endl;
-                    return IO_ERROR;
-                }
-                chown(optarg, AID_SHELL, AID_SHELL);
-            }
-            break;
-        }
-        case 'h': // falls through
-        default: // see unrecognized options
-            usage();
-            return USAGE;
-        }
+    if (optind >= arg.argc) {
+        // no options at all.
+        return OK;
+    }
+    mCommand = arg.argv[optind];
+    if (sAllCommands.find(mCommand) != sAllCommands.end()) {
+        ++optind;
+        return OK; // mCommand is set correctly
     }
 
-    if (mSelectedColumns == 0) {
-        mSelectedColumns = ENABLE_INTERFACE_NAME | ENABLE_SERVER_PID | ENABLE_CLIENT_PIDS;
+    if (mCommand.size() > 0 && mCommand[0] == '-') {
+        // first argument is an option, set command to "" (which is recognized as "list")
+        mCommand = "";
+        return OK;
     }
-    return OK;
+
+    mErr << arg.argv[0] << ": unrecognized option `" << arg.argv[optind] << "`" << std::endl;
+    usage();
+    return USAGE;
 }
 
-int Lshal::main(int argc, char **argv) {
-    Status status = parseArgs(argc, argv);
+Status Lshal::main(const Arg &arg) {
+    Status status = parseArgs(arg);
     if (status != OK) {
         return status;
     }
-    status = fetch();
-    postprocess();
-    dump();
-    return status;
+    if (mCommand == "help") {
+        usage(optind < arg.argc ? arg.argv[optind] : "");
+        return USAGE;
+    }
+    // Default command is list
+    if (mCommand == "list" || mCommand == "") {
+        return ListCommand{*this}.main(mCommand, arg);
+    }
+    if (mCommand == "debug") {
+        // TODO(b/37725279) implement this
+        return OK;
+    }
+    usage();
+    return USAGE;
+}
+
+NullableOStream<std::ostream> Lshal::err() const {
+    return mErr;
+}
+NullableOStream<std::ostream> Lshal::out() const {
+    return mOut;
 }
 
 void signalHandler(int sig) {
@@ -830,6 +216,7 @@
 }  // namespace android
 
 int main(int argc, char **argv) {
-    signal(SIGINT, ::android::lshal::signalHandler);
-    return ::android::lshal::Lshal{}.main(argc, argv);
+    using namespace ::android::lshal;
+    signal(SIGINT, signalHandler);
+    return Lshal{}.main(Arg{argc, argv});
 }