logcat/logcat.cpp

/*
 * Copyright (C) 2006-2017 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.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "logcat.h"

#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <math.h>
#include <sched.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/cdefs.h>
#include <sys/ioctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>

#include <memory>
#include <regex>
#include <string>
#include <utility>
#include <vector>

#include <android-base/file.h>
#include <android-base/macros.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <android-base/unique_fd.h>
#include <log/event_tag_map.h>
#include <log/logprint.h>
#include <private/android_logger.h>
#include <processgroup/sched_policy.h>
#include <system/thread_defs.h>

#define DEFAULT_MAX_ROTATED_LOGS 4

using android::base::StringPrintf;

struct log_device_t {
    const char* device;
    bool binary;
    struct logger* logger;
    struct logger_list* logger_list;
    bool printed;

    log_device_t* next;

    log_device_t(const char* d, bool b) {
        device = d;
        binary = b;
        next = nullptr;
        printed = false;
        logger = nullptr;
        logger_list = nullptr;
    }
};

class Logcat {
  public:
    ~Logcat();

    int Run(int argc, char** argv);

  private:
    void RotateLogs();
    void ProcessBuffer(log_device_t* dev, struct log_msg* buf);
    void MaybePrintStart(log_device_t* dev, bool print_dividers);
    void SetupOutputAndSchedulingPolicy(bool blocking);
    int SetLogFormat(const char* format_string);

    android::base::unique_fd output_fd_{dup(STDOUT_FILENO)};
    std::unique_ptr<AndroidLogFormat, decltype(&android_log_format_free)> logformat_{
            android_log_format_new(), &android_log_format_free};
    const char* output_file_name_ = nullptr;
    // 0 means "no log rotation"
    size_t log_rotate_size_kb_ = 0;
    // 0 means "unbounded"
    size_t max_rotated_logs_ = DEFAULT_MAX_ROTATED_LOGS;
    size_t out_byte_count_ = 0;
    int print_binary_ = 0;
    int dev_count_ = 0;  // >1 means multiple
    std::unique_ptr<std::regex> regex_;
    log_device_t* devices_ = nullptr;
    std::unique_ptr<EventTagMap, decltype(&android_closeEventTagMap)> event_tag_map_{
            nullptr, &android_closeEventTagMap};
    // 0 means "infinite"
    size_t max_count_ = 0;
    size_t print_count_ = 0;

    bool print_it_anyways_ = false;
    bool debug_ = false;
    bool has_opened_event_tag_map_ = false;
};

// logd prefixes records with a length field
#define RECORD_LENGTH_FIELD_SIZE_BYTES sizeof(uint32_t)

enum helpType { HELP_FALSE, HELP_TRUE, HELP_FORMAT };

// if show_help is set, newline required in fmt statement to transition to usage
static void LogcatPanic(enum helpType showHelp, const char* fmt, ...) __printflike(2, 3)
        __attribute__((__noreturn__));

#ifndef F2FS_IOC_SET_PIN_FILE
#define F2FS_IOCTL_MAGIC       0xf5
#define F2FS_IOC_SET_PIN_FILE _IOW(F2FS_IOCTL_MAGIC, 13, __u32)
#endif

static int openLogFile(const char* pathname, size_t sizeKB) {
    int fd = open(pathname, O_WRONLY | O_APPEND | O_CREAT | O_CLOEXEC, S_IRUSR | S_IWUSR);
    if (fd < 0) {
        return fd;
    }

    // no need to check errors
    __u32 set = 1;
    ioctl(fd, F2FS_IOC_SET_PIN_FILE, &set);
    fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, (sizeKB << 10));
    return fd;
}

void Logcat::RotateLogs() {
    // Can't rotate logs if we're not outputting to a file
    if (!output_file_name_) return;

    output_fd_.reset();

    // Compute the maximum number of digits needed to count up to
    // maxRotatedLogs in decimal.  eg:
    // maxRotatedLogs == 30
    //   -> log10(30) == 1.477
    //   -> maxRotationCountDigits == 2
    int max_rotation_count_digits =
            max_rotated_logs_ > 0 ? (int)(floor(log10(max_rotated_logs_) + 1)) : 0;

    for (int i = max_rotated_logs_; i > 0; i--) {
        std::string file1 =
                StringPrintf("%s.%.*d", output_file_name_, max_rotation_count_digits, i);

        std::string file0;
        if (!(i - 1)) {
            file0 = output_file_name_;
        } else {
            file0 = StringPrintf("%s.%.*d", output_file_name_, max_rotation_count_digits, i - 1);
        }

        if (!file0.length() || !file1.length()) {
            perror("while rotating log files");
            break;
        }

        int err = rename(file0.c_str(), file1.c_str());

        if (err < 0 && errno != ENOENT) {
            perror("while rotating log files");
        }
    }

    output_fd_.reset(openLogFile(output_file_name_, log_rotate_size_kb_));

    if (!output_fd_.ok()) {
        LogcatPanic(HELP_FALSE, "couldn't open output file");
    }

    out_byte_count_ = 0;
}

void Logcat::ProcessBuffer(log_device_t* dev, struct log_msg* buf) {
    int bytesWritten = 0;
    int err;
    AndroidLogEntry entry;
    char binaryMsgBuf[1024];

    if (dev->binary) {
        if (!event_tag_map_ && !has_opened_event_tag_map_) {
            event_tag_map_.reset(android_openEventTagMap(nullptr));
            has_opened_event_tag_map_ = true;
        }
        err = android_log_processBinaryLogBuffer(&buf->entry, &entry, event_tag_map_.get(),
                                                 binaryMsgBuf, sizeof(binaryMsgBuf));
        // printf(">>> pri=%d len=%d msg='%s'\n",
        //    entry.priority, entry.messageLen, entry.message);
    } else {
        err = android_log_processLogBuffer(&buf->entry, &entry);
    }
    if (err < 0 && !debug_) return;

    if (android_log_shouldPrintLine(logformat_.get(), std::string(entry.tag, entry.tagLen).c_str(),
                                    entry.priority)) {
        bool match = !regex_ ||
                     std::regex_search(entry.message, entry.message + entry.messageLen, *regex_);

        print_count_ += match;
        if (match || print_it_anyways_) {
            bytesWritten = android_log_printLogLine(logformat_.get(), output_fd_.get(), &entry);

            if (bytesWritten < 0) {
                LogcatPanic(HELP_FALSE, "output error");
            }
        }
    }

    out_byte_count_ += bytesWritten;

    if (log_rotate_size_kb_ > 0 && (out_byte_count_ / 1024) >= log_rotate_size_kb_) {
        RotateLogs();
    }
}

void Logcat::MaybePrintStart(log_device_t* dev, bool print_dividers) {
    if (!dev->printed || print_dividers) {
        if (dev_count_ > 1 && !print_binary_) {
            if (dprintf(output_fd_.get(), "--------- %s %s\n",
                        dev->printed ? "switch to" : "beginning of", dev->device) < 0) {
                LogcatPanic(HELP_FALSE, "output error");
            }
        }
        dev->printed = true;
    }
}

void Logcat::SetupOutputAndSchedulingPolicy(bool blocking) {
    if (!output_file_name_) return;

    if (blocking) {
        // Lower priority and set to batch scheduling if we are saving
        // the logs into files and taking continuous content.
        if (set_sched_policy(0, SP_BACKGROUND) < 0) {
            fprintf(stderr, "failed to set background scheduling policy\n");
        }

        struct sched_param param = {};
        if (sched_setscheduler((pid_t)0, SCHED_BATCH, &param) < 0) {
            fprintf(stderr, "failed to set to batch scheduler\n");
        }

        if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) {
            fprintf(stderr, "failed set to priority\n");
        }
    }

    output_fd_.reset(openLogFile(output_file_name_, log_rotate_size_kb_));

    if (!output_fd_.ok()) {
        LogcatPanic(HELP_FALSE, "couldn't open output file");
    }

    struct stat statbuf;
    if (fstat(output_fd_.get(), &statbuf) == -1) {
        output_fd_.reset();
        LogcatPanic(HELP_FALSE, "couldn't get output file stat\n");
    }

    if ((size_t)statbuf.st_size > SIZE_MAX || statbuf.st_size < 0) {
        output_fd_.reset();
        LogcatPanic(HELP_FALSE, "invalid output file stat\n");
    }

    out_byte_count_ = statbuf.st_size;
}

// clang-format off
static void show_help() {
    const char* cmd = getprogname();

    fprintf(stderr, "Usage: %s [options] [filterspecs]\n", cmd);

    fprintf(stderr, "options include:\n"
                    "  -s              Set default filter to silent. Equivalent to filterspec '*:S'\n"
                    "  -f <file>, --file=<file>               Log to file. Default is stdout\n"
                    "  -r <kbytes>, --rotate-kbytes=<kbytes>\n"
                    "                  Rotate log every kbytes. Requires -f option\n"
                    "  -n <count>, --rotate-count=<count>\n"
                    "                  Sets max number of rotated logs to <count>, default 4\n"
                    "  --id=<id>       If the signature id for logging to file changes, then clear\n"
                    "                  the fileset and continue\n"
                    "  -v <format>, --format=<format>\n"
                    "                  Sets log print format verb and adverbs, where <format> is:\n"
                    "                    brief help long process raw tag thread threadtime time\n"
                    "                  and individually flagged modifying adverbs can be added:\n"
                    "                    color descriptive epoch monotonic printable uid\n"
                    "                    usec UTC year zone\n"
                    "                  Multiple -v parameters or comma separated list of format and\n"
                    "                  format modifiers are allowed.\n"
                    // private and undocumented nsec, no signal, too much noise
                    // useful for -T or -t <timestamp> accurate testing though.
                    "  -D, --dividers  Print dividers between each log buffer\n"
                    "  -c, --clear     Clear (flush) the entire log and exit\n"
                    "                  if Log to File specified, clear fileset instead\n"
                    "  -d              Dump the log and then exit (don't block)\n"
                    "  -e <expr>, --regex=<expr>\n"
                    "                  Only print lines where the log message matches <expr>\n"
                    "                  where <expr> is a regular expression\n"
                    // Leave --head undocumented as alias for -m
                    "  -m <count>, --max-count=<count>\n"
                    "                  Quit after printing <count> lines. This is meant to be\n"
                    "                  paired with --regex, but will work on its own.\n"
                    "  --print         Paired with --regex and --max-count to let content bypass\n"
                    "                  regex filter but still stop at number of matches.\n"
                    // Leave --tail undocumented as alias for -t
                    "  -t <count>      Print only the most recent <count> lines (implies -d)\n"
                    "  -t '<time>'     Print most recent lines since specified time (implies -d)\n"
                    "  -T <count>      Print only the most recent <count> lines (does not imply -d)\n"
                    "  -T '<time>'     Print most recent lines since specified time (not imply -d)\n"
                    "                  count is pure numerical, time is 'MM-DD hh:mm:ss.mmm...'\n"
                    "                  'YYYY-MM-DD hh:mm:ss.mmm...' or 'sssss.mmm...' format\n"
                    "  -g, --buffer-size                      Get the size of the ring buffer.\n"
                    "  -G <size>, --buffer-size=<size>\n"
                    "                  Set size of log ring buffer, may suffix with K or M.\n"
                    "  -L, --last      Dump logs from prior to last reboot\n"
                    "  -b <buffer>, --buffer=<buffer>         Request alternate ring buffer, 'main',\n"
                    "                  'system', 'radio', 'events', 'crash', 'default' or 'all'.\n"
                    "                  Additionally, 'kernel' for userdebug and eng builds, and\n"
                    "                  'security' for Device Owner installations.\n"
                    "                  Multiple -b parameters or comma separated list of buffers are\n"
                    "                  allowed. Buffers interleaved.\n"
                    "                  Default -b main,system,crash,kernel.\n"
                    "  -B, --binary    Output the log in binary.\n"
                    "  -S, --statistics                       Output statistics.\n"
                    "  -p, --prune     Print prune white and ~black list. Service is specified as\n"
                    "                  UID, UID/PID or /PID. Weighed for quicker pruning if prefix\n"
                    "                  with ~, otherwise weighed for longevity if unadorned. All\n"
                    "                  other pruning activity is oldest first. Special case ~!\n"
                    "                  represents an automatic quicker pruning for the noisiest\n"
                    "                  UID as determined by the current statistics.\n"
                    "  -P '<list> ...', --prune='<list> ...'\n"
                    "                  Set prune white and ~black list, using same format as\n"
                    "                  listed above. Must be quoted.\n"
                    "  --pid=<pid>     Only prints logs from the given pid.\n"
                    // Check ANDROID_LOG_WRAP_DEFAULT_TIMEOUT value for match to 2 hours
                    "  --wrap          Sleep for 2 hours or when buffer about to wrap whichever\n"
                    "                  comes first. Improves efficiency of polling by providing\n"
                    "                  an about-to-wrap wakeup.\n");

    fprintf(stderr, "\nfilterspecs are a series of \n"
                   "  <tag>[:priority]\n\n"
                   "where <tag> is a log component tag (or * for all) and priority is:\n"
                   "  V    Verbose (default for <tag>)\n"
                   "  D    Debug (default for '*')\n"
                   "  I    Info\n"
                   "  W    Warn\n"
                   "  E    Error\n"
                   "  F    Fatal\n"
                   "  S    Silent (suppress all output)\n"
                   "\n'*' by itself means '*:D' and <tag> by itself means <tag>:V.\n"
                   "If no '*' filterspec or -s on command line, all filter defaults to '*:V'.\n"
                   "eg: '*:S <tag>' prints only <tag>, '<tag>:S' suppresses all <tag> log messages.\n"
                   "\nIf not specified on the command line, filterspec is set from ANDROID_LOG_TAGS.\n"
                   "\nIf not specified with -v on command line, format is set from ANDROID_PRINTF_LOG\n"
                   "or defaults to \"threadtime\"\n\n");
}

static void show_format_help() {
    fprintf(stderr,
        "-v <format>, --format=<format> options:\n"
        "  Sets log print format verb and adverbs, where <format> is:\n"
        "    brief long process raw tag thread threadtime time\n"
        "  and individually flagged modifying adverbs can be added:\n"
        "    color descriptive epoch monotonic printable uid usec UTC year zone\n"
        "\nSingle format verbs:\n"
        "  brief      — Display priority/tag and PID of the process issuing the message.\n"
        "  long       — Display all metadata fields, separate messages with blank lines.\n"
        "  process    — Display PID only.\n"
        "  raw        — Display the raw log message, with no other metadata fields.\n"
        "  tag        — Display the priority/tag only.\n"
        "  thread     — Display priority, PID and TID of process issuing the message.\n"
        "  threadtime — Display the date, invocation time, priority, tag, and the PID\n"
        "               and TID of the thread issuing the message. (the default format).\n"
        "  time       — Display the date, invocation time, priority/tag, and PID of the\n"
        "             process issuing the message.\n"
        "\nAdverb modifiers can be used in combination:\n"
        "  color       — Display in highlighted color to match priority. i.e. \x1B[38;5;231mVERBOSE\n"
        "                \x1B[38;5;75mDEBUG \x1B[38;5;40mINFO \x1B[38;5;166mWARNING \x1B[38;5;196mERROR FATAL\x1B[0m\n"
        "  descriptive — events logs only, descriptions from event-log-tags database.\n"
        "  epoch       — Display time as seconds since Jan 1 1970.\n"
        "  monotonic   — Display time as cpu seconds since last boot.\n"
        "  printable   — Ensure that any binary logging content is escaped.\n"
        "  uid         — If permitted, display the UID or Android ID of logged process.\n"
        "  usec        — Display time down the microsecond precision.\n"
        "  UTC         — Display time as UTC.\n"
        "  year        — Add the year to the displayed time.\n"
        "  zone        — Add the local timezone to the displayed time.\n"
        "  \"<zone>\"    — Print using this public named timezone (experimental).\n\n"
    );
}
// clang-format on

int Logcat::SetLogFormat(const char* format_string) {
    AndroidLogPrintFormat format = android_log_formatFromString(format_string);

    // invalid string?
    if (format == FORMAT_OFF) return -1;

    return android_log_setPrintFormat(logformat_.get(), format);
}

static std::pair<unsigned long, const char*> format_of_size(unsigned long value) {
    static const char multipliers[][3] = {{""}, {"Ki"}, {"Mi"}, {"Gi"}};
    size_t i;
    for (i = 0;
         (i < sizeof(multipliers) / sizeof(multipliers[0])) && (value >= 1024);
         value /= 1024, ++i)
        ;
    return std::make_pair(value, multipliers[i]);
}

// String to unsigned int, returns -1 if it fails
static bool getSizeTArg(const char* ptr, size_t* val, size_t min = 0,
                        size_t max = SIZE_MAX) {
    if (!ptr) return false;

    char* endp;
    errno = 0;
    size_t ret = (size_t)strtoll(ptr, &endp, 0);

    if (endp[0] || errno) return false;

    if ((ret > max) || (ret < min)) return false;

    *val = ret;
    return true;
}

static void LogcatPanic(enum helpType showHelp, const char* fmt, ...) {
    va_list args;
    va_start(args, fmt);
    vfprintf(stderr, fmt, args);
    va_end(args);

    switch (showHelp) {
        case HELP_TRUE:
            show_help();
            break;
        case HELP_FORMAT:
            show_format_help();
            break;
        case HELP_FALSE:
        default:
            break;
    }

    exit(EXIT_FAILURE);
}

static char* parseTime(log_time& t, const char* cp) {
    char* ep = t.strptime(cp, "%m-%d %H:%M:%S.%q");
    if (ep) return ep;
    ep = t.strptime(cp, "%Y-%m-%d %H:%M:%S.%q");
    if (ep) return ep;
    return t.strptime(cp, "%s.%q");
}

// Find last logged line in <outputFileName>, or <outputFileName>.1
static log_time lastLogTime(const char* outputFileName) {
    log_time retval(log_time::EPOCH);
    if (!outputFileName) return retval;

    std::string directory;
    const char* file = strrchr(outputFileName, '/');
    if (!file) {
        directory = ".";
        file = outputFileName;
    } else {
        directory = std::string(outputFileName, file - outputFileName);
        ++file;
    }

    std::unique_ptr<DIR, int (*)(DIR*)> dir(opendir(directory.c_str()),
                                            closedir);
    if (!dir.get()) return retval;

    log_time now(android_log_clockid());

    size_t len = strlen(file);
    log_time modulo(0, NS_PER_SEC);
    struct dirent* dp;

    while (!!(dp = readdir(dir.get()))) {
        if ((dp->d_type != DT_REG) || !!strncmp(dp->d_name, file, len) ||
            (dp->d_name[len] && ((dp->d_name[len] != '.') ||
                                 (strtoll(dp->d_name + 1, nullptr, 10) != 1)))) {
            continue;
        }

        std::string file_name = directory;
        file_name += "/";
        file_name += dp->d_name;
        std::string file;
        if (!android::base::ReadFileToString(file_name, &file)) continue;

        bool found = false;
        for (const auto& line : android::base::Split(file, "\n")) {
            log_time t(log_time::EPOCH);
            char* ep = parseTime(t, line.c_str());
            if (!ep || (*ep != ' ')) continue;
            // determine the time precision of the logs (eg: msec or usec)
            for (unsigned long mod = 1UL; mod < modulo.tv_nsec; mod *= 10) {
                if (t.tv_nsec % (mod * 10)) {
                    modulo.tv_nsec = mod;
                    break;
                }
            }
            // We filter any times later than current as we may not have the
            // year stored with each log entry. Also, since it is possible for
            // entries to be recorded out of order (very rare) we select the
            // maximum we find just in case.
            if ((t < now) && (t > retval)) {
                retval = t;
                found = true;
            }
        }
        // We count on the basename file to be the definitive end, so stop here.
        if (!dp->d_name[len] && found) break;
    }
    if (retval == log_time::EPOCH) return retval;
    // tail_time prints matching or higher, round up by the modulo to prevent
    // a replay of the last entry we have just checked.
    retval += modulo;
    return retval;
}

void reportErrorName(const char** current, const char* name,
                     bool blockSecurity) {
    if (*current) return;
    if (!blockSecurity || (android_name_to_log_id(name) != LOG_ID_SECURITY)) {
        *current = name;
    }
}

int Logcat::Run(int argc, char** argv) {
    int err;
    bool hasSetLogFormat = false;
    bool clearLog = false;
    bool allSelected = false;
    bool getLogSize = false;
    bool getPruneList = false;
    bool printStatistics = false;
    bool printDividers = false;
    unsigned long setLogSize = 0;
    const char* setPruneList = nullptr;
    const char* setId = nullptr;
    int mode = ANDROID_LOG_RDONLY;
    std::string forceFilters;
    log_device_t* dev;
    struct logger_list* logger_list;
    size_t tail_lines = 0;
    log_time tail_time(log_time::EPOCH);
    size_t pid = 0;
    bool got_t = false;

    // object instantiations before goto's can happen
    log_device_t unexpected("unexpected", false);
    const char* openDeviceFail = nullptr;
    const char* clearFail = nullptr;
    const char* setSizeFail = nullptr;
    const char* getSizeFail = nullptr;

    if (argc == 2 && !strcmp(argv[1], "--help")) {
        show_help();
        return EXIT_SUCCESS;
    }

    // meant to catch comma-delimited values, but cast a wider
    // net for stability dealing with possible mistaken inputs.
    static const char delimiters[] = ",:; \t\n\r\f";

    optind = 0;
    while (true) {
        int option_index = 0;
        // list of long-argument only strings for later comparison
        static const char pid_str[] = "pid";
        static const char debug_str[] = "debug";
        static const char id_str[] = "id";
        static const char wrap_str[] = "wrap";
        static const char print_str[] = "print";
        // clang-format off
        static const struct option long_options[] = {
          { "binary",        no_argument,       nullptr, 'B' },
          { "buffer",        required_argument, nullptr, 'b' },
          { "buffer-size",   optional_argument, nullptr, 'g' },
          { "clear",         no_argument,       nullptr, 'c' },
          { debug_str,       no_argument,       nullptr, 0 },
          { "dividers",      no_argument,       nullptr, 'D' },
          { "file",          required_argument, nullptr, 'f' },
          { "format",        required_argument, nullptr, 'v' },
          // hidden and undocumented reserved alias for --regex
          { "grep",          required_argument, nullptr, 'e' },
          // hidden and undocumented reserved alias for --max-count
          { "head",          required_argument, nullptr, 'm' },
          { "help",          no_argument,       nullptr, 'h' },
          { id_str,          required_argument, nullptr, 0 },
          { "last",          no_argument,       nullptr, 'L' },
          { "max-count",     required_argument, nullptr, 'm' },
          { pid_str,         required_argument, nullptr, 0 },
          { print_str,       no_argument,       nullptr, 0 },
          { "prune",         optional_argument, nullptr, 'p' },
          { "regex",         required_argument, nullptr, 'e' },
          { "rotate-count",  required_argument, nullptr, 'n' },
          { "rotate-kbytes", required_argument, nullptr, 'r' },
          { "statistics",    no_argument,       nullptr, 'S' },
          // hidden and undocumented reserved alias for -t
          { "tail",          required_argument, nullptr, 't' },
          // support, but ignore and do not document, the optional argument
          { wrap_str,        optional_argument, nullptr, 0 },
          { nullptr,         0,                 nullptr, 0 }
        };
        // clang-format on

        int c = getopt_long(argc, argv, ":cdDhLt:T:gG:sQf:r:n:v:b:BSpP:m:e:", long_options,
                            &option_index);
        if (c == -1) break;

        switch (c) {
            case 0:
                // only long options
                if (long_options[option_index].name == pid_str) {
                    if (pid != 0) {
                        LogcatPanic(HELP_TRUE, "Only supports one PID argument.\n");
                    }

                    // ToDo: determine runtime PID_MAX?
                    if (!getSizeTArg(optarg, &pid, 1)) {
                        LogcatPanic(HELP_TRUE, "%s %s out of range\n",
                                    long_options[option_index].name, optarg);
                    }
                    break;
                }
                if (long_options[option_index].name == wrap_str) {
                    mode |= ANDROID_LOG_WRAP | ANDROID_LOG_RDONLY |
                            ANDROID_LOG_NONBLOCK;
                    // ToDo: implement API that supports setting a wrap timeout
                    size_t dummy = ANDROID_LOG_WRAP_DEFAULT_TIMEOUT;
                    if (optarg && !getSizeTArg(optarg, &dummy, 1)) {
                        LogcatPanic(HELP_TRUE, "%s %s out of range\n",
                                    long_options[option_index].name, optarg);
                    }
                    if (dummy != ANDROID_LOG_WRAP_DEFAULT_TIMEOUT) {
                        fprintf(stderr, "WARNING: %s %u seconds, ignoring %zu\n",
                                long_options[option_index].name, ANDROID_LOG_WRAP_DEFAULT_TIMEOUT,
                                dummy);
                    }
                    break;
                }
                if (long_options[option_index].name == print_str) {
                    print_it_anyways_ = true;
                    break;
                }
                if (long_options[option_index].name == debug_str) {
                    debug_ = true;
                    break;
                }
                if (long_options[option_index].name == id_str) {
                    setId = (optarg && optarg[0]) ? optarg : nullptr;
                }
                break;

            case 's':
                // default to all silent
                android_log_addFilterRule(logformat_.get(), "*:s");
                break;

            case 'c':
                clearLog = true;
                mode |= ANDROID_LOG_WRONLY;
                break;

            case 'L':
                mode |= ANDROID_LOG_RDONLY | ANDROID_LOG_PSTORE |
                        ANDROID_LOG_NONBLOCK;
                break;

            case 'd':
                mode |= ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK;
                break;

            case 't':
                got_t = true;
                mode |= ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK;
                FALLTHROUGH_INTENDED;
            case 'T':
                if (strspn(optarg, "0123456789") != strlen(optarg)) {
                    char* cp = parseTime(tail_time, optarg);
                    if (!cp) {
                        LogcatPanic(HELP_FALSE, "-%c \"%s\" not in time format\n", c, optarg);
                    }
                    if (*cp) {
                        char ch = *cp;
                        *cp = '\0';
                        fprintf(stderr, "WARNING: -%c \"%s\"\"%c%s\" time truncated\n", c, optarg,
                                ch, cp + 1);
                        *cp = ch;
                    }
                } else {
                    if (!getSizeTArg(optarg, &tail_lines, 1)) {
                        fprintf(stderr, "WARNING: -%c %s invalid, setting to 1\n", c, optarg);
                        tail_lines = 1;
                    }
                }
                break;

            case 'D':
                printDividers = true;
                break;

            case 'e':
                regex_.reset(new std::regex(optarg));
                break;

            case 'm': {
                if (!getSizeTArg(optarg, &max_count_)) {
                    LogcatPanic(HELP_FALSE, "-%c \"%s\" isn't an integer greater than zero\n", c,
                                optarg);
                }
            } break;

            case 'g':
                if (!optarg) {
                    getLogSize = true;
                    break;
                }
                FALLTHROUGH_INTENDED;

            case 'G': {
                char* cp;
                if (strtoll(optarg, &cp, 0) > 0) {
                    setLogSize = strtoll(optarg, &cp, 0);
                } else {
                    setLogSize = 0;
                }

                switch (*cp) {
                    case 'g':
                    case 'G':
                        setLogSize *= 1024;
                        FALLTHROUGH_INTENDED;
                    case 'm':
                    case 'M':
                        setLogSize *= 1024;
                        FALLTHROUGH_INTENDED;
                    case 'k':
                    case 'K':
                        setLogSize *= 1024;
                        FALLTHROUGH_INTENDED;
                    case '\0':
                        break;

                    default:
                        setLogSize = 0;
                }

                if (!setLogSize) {
                    LogcatPanic(HELP_FALSE, "ERROR: -G <num><multiplier>\n");
                }
            } break;

            case 'p':
                if (!optarg) {
                    getPruneList = true;
                    break;
                }
                FALLTHROUGH_INTENDED;

            case 'P':
                setPruneList = optarg;
                break;

            case 'b': {
                std::unique_ptr<char, void (*)(void*)> buffers(strdup(optarg), free);
                char* arg = buffers.get();
                unsigned idMask = 0;
                char* sv = nullptr;  // protect against -ENOMEM above
                while (!!(arg = strtok_r(arg, delimiters, &sv))) {
                    if (!strcmp(arg, "default")) {
                        idMask |= (1 << LOG_ID_MAIN) | (1 << LOG_ID_SYSTEM) |
                                  (1 << LOG_ID_CRASH);
                    } else if (!strcmp(arg, "all")) {
                        allSelected = true;
                        idMask = (unsigned)-1;
                    } else {
                        log_id_t log_id = android_name_to_log_id(arg);
                        const char* name = android_log_id_to_name(log_id);

                        if (!!strcmp(name, arg)) {
                            LogcatPanic(HELP_TRUE, "unknown buffer %s\n", arg);
                        }
                        if (log_id == LOG_ID_SECURITY) allSelected = false;
                        idMask |= (1 << log_id);
                    }
                    arg = nullptr;
                }

                for (int i = LOG_ID_MIN; i < LOG_ID_MAX; ++i) {
                    const char* name = android_log_id_to_name((log_id_t)i);
                    log_id_t log_id = android_name_to_log_id(name);

                    if (log_id != (log_id_t)i) continue;
                    if (!(idMask & (1 << i))) continue;

                    bool found = false;
                    for (dev = devices_; dev; dev = dev->next) {
                        if (!strcmp(name, dev->device)) {
                            found = true;
                            break;
                        }
                        if (!dev->next) break;
                    }
                    if (found) continue;

                    bool binary = !strcmp(name, "events") ||
                                  !strcmp(name, "security") ||
                                  !strcmp(name, "stats");
                    log_device_t* d = new log_device_t(name, binary);

                    if (dev) {
                        dev->next = d;
                        dev = d;
                    } else {
                        devices_ = dev = d;
                    }
                    dev_count_++;
                }
            } break;

            case 'B':
                print_binary_ = 1;
                break;

            case 'f':
                if ((tail_time == log_time::EPOCH) && !tail_lines) {
                    tail_time = lastLogTime(optarg);
                }
                // redirect output to a file
                output_file_name_ = optarg;
                break;

            case 'r':
                if (!getSizeTArg(optarg, &log_rotate_size_kb_, 1)) {
                    LogcatPanic(HELP_TRUE, "Invalid parameter \"%s\" to -r\n", optarg);
                }
                break;

            case 'n':
                if (!getSizeTArg(optarg, &max_rotated_logs_, 1)) {
                    LogcatPanic(HELP_TRUE, "Invalid parameter \"%s\" to -n\n", optarg);
                }
                break;

            case 'v': {
                if (!strcmp(optarg, "help") || !strcmp(optarg, "--help")) {
                    show_format_help();
                    return EXIT_SUCCESS;
                }
                std::unique_ptr<char, void (*)(void*)> formats(strdup(optarg), free);
                char* arg = formats.get();
                char* sv = nullptr;  // protect against -ENOMEM above
                while (!!(arg = strtok_r(arg, delimiters, &sv))) {
                    err = SetLogFormat(arg);
                    if (err < 0) {
                        LogcatPanic(HELP_FORMAT, "Invalid parameter \"%s\" to -v\n", arg);
                    }
                    arg = nullptr;
                    if (err) hasSetLogFormat = true;
                }
            } break;

            case 'Q':
#define LOGCAT_FILTER "androidboot.logcat="
#define CONSOLE_PIPE_OPTION "androidboot.consolepipe="
#define CONSOLE_OPTION "androidboot.console="
#define QEMU_PROPERTY "ro.kernel.qemu"
#define QEMU_CMDLINE "qemu.cmdline"
                // This is a *hidden* option used to start a version of logcat
                // in an emulated device only.  It basically looks for
                // androidboot.logcat= on the kernel command line.  If
                // something is found, it extracts a log filter and uses it to
                // run the program. The logcat output will go to consolepipe if
                // androiboot.consolepipe (e.g. qemu_pipe) is given, otherwise,
                // it goes to androidboot.console (e.g. tty)
                {
                    // if not in emulator, exit quietly
                    if (false == android::base::GetBoolProperty(QEMU_PROPERTY, false)) {
                        return EXIT_SUCCESS;
                    }

                    std::string cmdline = android::base::GetProperty(QEMU_CMDLINE, "");
                    if (cmdline.empty()) {
                        android::base::ReadFileToString("/proc/cmdline", &cmdline);
                    }

                    const char* logcatFilter = strstr(cmdline.c_str(), LOGCAT_FILTER);
                    // if nothing found or invalid filters, exit quietly
                    if (!logcatFilter) {
                        return EXIT_SUCCESS;
                    }

                    const char* p = logcatFilter + strlen(LOGCAT_FILTER);
                    const char* q = strpbrk(p, " \t\n\r");
                    if (!q) q = p + strlen(p);
                    forceFilters = std::string(p, q);

                    // redirect our output to the emulator console pipe or console
                    const char* consolePipe =
                        strstr(cmdline.c_str(), CONSOLE_PIPE_OPTION);
                    const char* console =
                        strstr(cmdline.c_str(), CONSOLE_OPTION);

                    if (consolePipe) {
                        p = consolePipe + strlen(CONSOLE_PIPE_OPTION);
                    } else if (console) {
                        p = console + strlen(CONSOLE_OPTION);
                    } else {
                        return EXIT_FAILURE;
                    }

                    q = strpbrk(p, " \t\n\r");
                    int len = q ? q - p : strlen(p);
                    std::string devname = "/dev/" + std::string(p, len);
                    std::string pipePurpose("pipe:logcat");
                    if (consolePipe) {
                        // example: "qemu_pipe,pipe:logcat"
                        // upon opening of /dev/qemu_pipe, the "pipe:logcat"
                        // string with trailing '\0' should be written to the fd
                        size_t pos = devname.find(',');
                        if (pos != std::string::npos) {
                            pipePurpose = devname.substr(pos + 1);
                            devname = devname.substr(0, pos);
                        }
                    }

                    fprintf(stderr, "logcat using %s\n", devname.c_str());

                    int fd = open(devname.c_str(), O_WRONLY | O_CLOEXEC);
                    if (fd < 0) {
                        break;
                    }

                    if (consolePipe) {
                        // need the trailing '\0'
                        if (!android::base::WriteFully(fd, pipePurpose.c_str(),
                                                       pipePurpose.size() + 1)) {
                            close(fd);
                            return EXIT_FAILURE;
                        }
                    }
                    // close output and error channels, replace with console
                    dup2(fd, STDOUT_FILENO);
                    dup2(fd, STDERR_FILENO);
                    close(fd);
                }
                break;

            case 'S':
                printStatistics = true;
                break;

            case ':':
                LogcatPanic(HELP_TRUE, "Option -%c needs an argument\n", optopt);

            case 'h':
                show_help();
                show_format_help();
                return EXIT_SUCCESS;

            default:
                LogcatPanic(HELP_TRUE, "Unrecognized Option %c\n", optopt);
        }
    }

    if (max_count_ && got_t) {
        LogcatPanic(HELP_TRUE, "Cannot use -m (--max-count) and -t together\n");
    }
    if (print_it_anyways_ && (!regex_ || !max_count_)) {
        // One day it would be nice if --print -v color and --regex <expr>
        // could play with each other and show regex highlighted content.
        fprintf(stderr,
                "WARNING: "
                "--print ignored, to be used in combination with\n"
                "         "
                "--regex <expr> and --max-count <N>\n");
        print_it_anyways_ = false;
    }

    if (!devices_) {
        dev = devices_ = new log_device_t("main", false);
        dev_count_ = 1;
        if (android_name_to_log_id("system") == LOG_ID_SYSTEM) {
            dev = dev->next = new log_device_t("system", false);
            dev_count_++;
        }
        if (android_name_to_log_id("crash") == LOG_ID_CRASH) {
            dev = dev->next = new log_device_t("crash", false);
            dev_count_++;
        }
        if (android_name_to_log_id("kernel") == LOG_ID_KERNEL) {
            dev = dev->next = new log_device_t("kernel", false);
            dev_count_++;
        }
    }

    if (log_rotate_size_kb_ != 0 && !output_file_name_) {
        LogcatPanic(HELP_TRUE, "-r requires -f as well\n");
    }

    if (setId != 0) {
        if (!output_file_name_) {
            LogcatPanic(HELP_TRUE, "--id='%s' requires -f as well\n", setId);
        }

        std::string file_name = StringPrintf("%s.id", output_file_name_);
        std::string file;
        bool file_ok = android::base::ReadFileToString(file_name, &file);
        android::base::WriteStringToFile(setId, file_name, S_IRUSR | S_IWUSR,
                                         getuid(), getgid());
        if (!file_ok || !file.compare(setId)) setId = nullptr;
    }

    if (!hasSetLogFormat) {
        const char* logFormat = getenv("ANDROID_PRINTF_LOG");

        if (!!logFormat) {
            std::unique_ptr<char, void (*)(void*)> formats(strdup(logFormat),
                                                           free);
            char* sv = nullptr;  // protect against -ENOMEM above
            char* arg = formats.get();
            while (!!(arg = strtok_r(arg, delimiters, &sv))) {
                err = SetLogFormat(arg);
                // environment should not cause crash of logcat
                if (err < 0) {
                    fprintf(stderr, "invalid format in ANDROID_PRINTF_LOG '%s'\n", arg);
                }
                arg = nullptr;
                if (err > 0) hasSetLogFormat = true;
            }
        }
        if (!hasSetLogFormat) {
            SetLogFormat("threadtime");
        }
    }

    if (forceFilters.size()) {
        err = android_log_addFilterString(logformat_.get(), forceFilters.c_str());
        if (err < 0) {
            LogcatPanic(HELP_FALSE, "Invalid filter expression in logcat args\n");
        }
    } else if (argc == optind) {
        // Add from environment variable
        const char* env_tags_orig = getenv("ANDROID_LOG_TAGS");

        if (!!env_tags_orig) {
            err = android_log_addFilterString(logformat_.get(), env_tags_orig);

            if (err < 0) {
                LogcatPanic(HELP_TRUE, "Invalid filter expression in ANDROID_LOG_TAGS\n");
            }
        }
    } else {
        // Add from commandline
        for (int i = optind ; i < argc ; i++) {
            // skip stderr redirections of _all_ kinds
            if ((argv[i][0] == '2') && (argv[i][1] == '>')) continue;
            // skip stdout redirections of _all_ kinds
            if (argv[i][0] == '>') continue;

            err = android_log_addFilterString(logformat_.get(), argv[i]);
            if (err < 0) {
                LogcatPanic(HELP_TRUE, "Invalid filter expression '%s'\n", argv[i]);
            }
        }
    }

    dev = devices_;
    if (tail_time != log_time::EPOCH) {
        logger_list = android_logger_list_alloc_time(mode, tail_time, pid);
    } else {
        logger_list = android_logger_list_alloc(mode, tail_lines, pid);
    }
    // We have three orthogonal actions below to clear, set log size and
    // get log size. All sharing the same iteration loop.
    while (dev) {
        dev->logger_list = logger_list;
        dev->logger = android_logger_open(logger_list,
                                          android_name_to_log_id(dev->device));
        if (!dev->logger) {
            reportErrorName(&openDeviceFail, dev->device, allSelected);
            dev = dev->next;
            continue;
        }

        if (clearLog || setId) {
            if (output_file_name_) {
                int max_rotation_count_digits =
                        max_rotated_logs_ > 0 ? (int)(floor(log10(max_rotated_logs_) + 1)) : 0;

                for (int i = max_rotated_logs_; i >= 0; --i) {
                    std::string file;

                    if (!i) {
                        file = output_file_name_;
                    } else {
                        file = StringPrintf("%s.%.*d", output_file_name_, max_rotation_count_digits,
                                            i);
                    }

                    if (!file.length()) {
                        perror("while clearing log files");
                        reportErrorName(&clearFail, dev->device, allSelected);
                        break;
                    }

                    err = unlink(file.c_str());

                    if (err < 0 && errno != ENOENT && !clearFail) {
                        perror("while clearing log files");
                        reportErrorName(&clearFail, dev->device, allSelected);
                    }
                }
            } else if (android_logger_clear(dev->logger)) {
                reportErrorName(&clearFail, dev->device, allSelected);
            }
        }

        if (setLogSize) {
            if (android_logger_set_log_size(dev->logger, setLogSize)) {
                reportErrorName(&setSizeFail, dev->device, allSelected);
            }
        }

        if (getLogSize) {
            long size = android_logger_get_log_size(dev->logger);
            long readable = android_logger_get_log_readable_size(dev->logger);

            if ((size < 0) || (readable < 0)) {
                reportErrorName(&getSizeFail, dev->device, allSelected);
            } else {
                auto size_format = format_of_size(size);
                auto readable_format = format_of_size(readable);
                std::string str = android::base::StringPrintf(
                       "%s: ring buffer is %lu %sB (%lu %sB consumed),"
                         " max entry is %d B, max payload is %d B\n",
                       dev->device,
                       size_format.first, size_format.second,
                       readable_format.first, readable_format.second,
                       (int)LOGGER_ENTRY_MAX_LEN,
                       (int)LOGGER_ENTRY_MAX_PAYLOAD);
                TEMP_FAILURE_RETRY(write(output_fd_.get(), str.data(), str.length()));
            }
        }

        dev = dev->next;
    }

    // report any errors in the above loop and exit
    if (openDeviceFail) {
        LogcatPanic(HELP_FALSE, "Unable to open log device '%s'\n", openDeviceFail);
    }
    if (clearFail) {
        LogcatPanic(HELP_FALSE, "failed to clear the '%s' log\n", clearFail);
    }
    if (setSizeFail) {
        LogcatPanic(HELP_FALSE, "failed to set the '%s' log size\n", setSizeFail);
    }
    if (getSizeFail) {
        LogcatPanic(HELP_FALSE, "failed to get the readable '%s' log size", getSizeFail);
    }

    if (setPruneList) {
        size_t len = strlen(setPruneList);
        // extra 32 bytes are needed by android_logger_set_prune_list
        size_t bLen = len + 32;
        char* buf = nullptr;
        if (asprintf(&buf, "%-*s", (int)(bLen - 1), setPruneList) > 0) {
            buf[len] = '\0';
            if (android_logger_set_prune_list(logger_list, buf, bLen)) {
                LogcatPanic(HELP_FALSE, "failed to set the prune list");
            }
            free(buf);
        } else {
            LogcatPanic(HELP_FALSE, "failed to set the prune list (alloc)");
        }
        return EXIT_SUCCESS;
    }

    if (printStatistics || getPruneList) {
        size_t len = 8192;
        char* buf;

        for (int retry = 32; (retry >= 0) && ((buf = new char[len]));
             delete[] buf, buf = nullptr, --retry) {
            if (getPruneList) {
                android_logger_get_prune_list(logger_list, buf, len);
            } else {
                android_logger_get_statistics(logger_list, buf, len);
            }
            buf[len - 1] = '\0';
            if (atol(buf) < 3) {
                delete[] buf;
                buf = nullptr;
                break;
            }
            size_t ret = atol(buf) + 1;
            if (ret <= len) {
                len = ret;
                break;
            }
            len = ret;
        }

        if (!buf) {
            LogcatPanic(HELP_FALSE, "failed to read data");
        }

        // remove trailing FF
        char* cp = buf + len - 1;
        *cp = '\0';
        bool truncated = *--cp != '\f';
        if (!truncated) *cp = '\0';

        // squash out the byte count
        cp = buf;
        if (!truncated) {
            while (isdigit(*cp)) ++cp;
            if (*cp == '\n') ++cp;
        }

        len = strlen(cp);
        TEMP_FAILURE_RETRY(write(output_fd_.get(), cp, len));
        delete[] buf;
        return EXIT_SUCCESS;
    }

    if (getLogSize || setLogSize || clearLog) return EXIT_SUCCESS;

    SetupOutputAndSchedulingPolicy(!(mode & ANDROID_LOG_NONBLOCK));

    dev = nullptr;

    while (!max_count_ || print_count_ < max_count_) {
        struct log_msg log_msg;
        int ret = android_logger_list_read(logger_list, &log_msg);
        if (!ret) {
            LogcatPanic(HELP_FALSE, "read: unexpected EOF!\n");
        }

        if (ret < 0) {
            if (ret == -EAGAIN) break;

            if (ret == -EIO) {
                LogcatPanic(HELP_FALSE, "read: unexpected EOF!\n");
            }
            if (ret == -EINVAL) {
                LogcatPanic(HELP_FALSE, "read: unexpected length.\n");
            }
            LogcatPanic(HELP_FALSE, "logcat read failure\n");
        }

        log_device_t* d;
        for (d = devices_; d; d = d->next) {
            if (android_name_to_log_id(d->device) == log_msg.id()) break;
        }
        if (!d) {
            dev_count_ = 2;  // set to Multiple
            d = &unexpected;
            d->binary = log_msg.id() == LOG_ID_EVENTS;
        }

        if (dev != d) {
            dev = d;
            MaybePrintStart(dev, printDividers);
        }
        if (print_binary_) {
            TEMP_FAILURE_RETRY(write(output_fd_.get(), &log_msg, log_msg.len()));
        } else {
            ProcessBuffer(dev, &log_msg);
        }
    }
    return EXIT_SUCCESS;
}

int RunLogcat(int argc, char** argv) {
    Logcat logcat;
    return logcat.Run(argc, argv);
}

Logcat::~Logcat() {
    // generic cleanup of devices list to handle all possible dirty cases
    log_device_t* dev;
    while (!!(dev = devices_)) {
        struct logger_list* logger_list = dev->logger_list;
        if (logger_list) {
            for (log_device_t* d = dev; d; d = d->next) {
                if (d->logger_list == logger_list) d->logger_list = nullptr;
            }
            android_logger_list_free(logger_list);
        }
        devices_ = dev->next;
        delete dev;
    }
}