mythmiscutil.cpp

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#include "mythmiscutil.h"
 
// C++ headers
#include <array>
#include <cerrno>
#include <cstdlib>
#include <ctime>
#include <iostream>
 
// POSIX
#include <unistd.h>
#include <fcntl.h>
#include <sched.h>
 
// System specific C headers
#include "compat.h"
 
#ifdef linux
#include <sys/vfs.h>
#include <sys/sysinfo.h>
#include <sys/stat.h> // for umask, chmod
#endif
 
#if CONFIG_DARWIN
#include <mach/mach.h>
#endif
 
#ifdef BSD
#include <sys/mount.h>  // for struct statfs
#include <sys/sysctl.h>
#include <sys/stat.h> // for umask, chmod
#endif
 
// Qt headers
#include <QReadWriteLock>
#include <QNetworkProxy>
#include <QStringList>
#include <QDataStream>
#include <QUdpSocket>
#include <QFileInfo>
#include <QFile>
#include <QDir>
#include <QUrl>
#include <QHostAddress>
#include <QDataStream>
#include <QRegularExpression>
#include <QRegularExpressionMatchIterator>
 
// Myth headers
#include "mythcorecontext.h"
#include "exitcodes.h"
#include "mythlogging.h"
#include "mythsocket.h"
#include "mythcoreutil.h"
#include "mythsystemlegacy.h"
 
#include "mythconfig.h" // for CONFIG_DARWIN
 
#if QT_VERSION < QT_VERSION_CHECK(5,10,0)
#define qEnvironmentVariable getenv
#endif
 
bool getUptime(std::chrono::seconds &uptime)
{
#ifdef __linux__
    struct sysinfo sinfo {};
    if (sysinfo(&sinfo) == -1)
    {
        LOG(VB_GENERAL, LOG_ERR, "sysinfo() error");
        return false;
    }
    uptime = std::chrono::seconds(sinfo.uptime);
 
#elif defined(__FreeBSD__) || CONFIG_DARWIN
 
    std::array<int,2> mib { CTL_KERN, KERN_BOOTTIME };
    struct timeval bootTime;
    size_t         len;
 
    // Uptime is calculated. Get this machine's boot time
    // and subtract it from the current machine time
    len    = sizeof(bootTime);
    if (sysctl(mib.data(), 2, &bootTime, &len, nullptr, 0) == -1)
    {
        LOG(VB_GENERAL, LOG_ERR, "sysctl() error");
        return false;
    }
    uptime = std::chrono::seconds(time(nullptr) - bootTime.tv_sec);
#elif defined(_WIN32)
    uptime = std::chrono::seconds(::GetTickCount() / 1000);
#else
    // Hmmm. Not Linux, not FreeBSD or Darwin. What else is there :-)
    LOG(VB_GENERAL, LOG_NOTICE, "Unknown platform. How do I get the uptime?");
    return false;
#endif
 
    return true;
}
 
bool getMemStats(int &totalMB, int &freeMB, int &totalVM, int &freeVM)
{
#ifdef __linux__
    const size_t MB = (1024*1024);
    struct sysinfo sinfo {};
    if (sysinfo(&sinfo) == -1)
    {
        LOG(VB_GENERAL, LOG_ERR,
            "getMemStats(): Error, sysinfo() call failed.");
        return false;
    }
 
    totalMB = (int)((sinfo.totalram  * sinfo.mem_unit)/MB);
    freeMB  = (int)((sinfo.freeram   * sinfo.mem_unit)/MB);
    totalVM = (int)((sinfo.totalswap * sinfo.mem_unit)/MB);
    freeVM  = (int)((sinfo.freeswap  * sinfo.mem_unit)/MB);
    return true;
#elif CONFIG_DARWIN
    mach_port_t             mp;
    mach_msg_type_number_t  count;
    vm_size_t               pageSize;
    vm_statistics_data_t    s;
 
    mp = mach_host_self();
 
    // VM page size
    if (host_page_size(mp, &pageSize) != KERN_SUCCESS)
        pageSize = 4096;   // If we can't look it up, 4K is a good guess
 
    count = HOST_VM_INFO_COUNT;
    if (host_statistics(mp, HOST_VM_INFO,
                        (host_info_t)&s, &count) != KERN_SUCCESS)
    {
        LOG(VB_GENERAL, LOG_ERR, "getMemStats(): Error, "
            "failed to get virtual memory statistics.");
        return false;
    }
 
    pageSize >>= 10;  // This gives usages in KB
    totalMB = (s.active_count + s.inactive_count +
               s.wire_count + s.free_count) * pageSize / 1024;
    freeMB  = s.free_count * pageSize / 1024;
 
 
    // This is a real hack. I have not found a way to ask the kernel how much
    // swap it is using, and the dynamic_pager daemon doesn't even seem to be
    // able to report what filesystem it is using for the swapfiles. So, we do:
    int64_t total, used, free;
    free = getDiskSpace("/private/var/vm", total, used);
    totalVM = (int)(total >> 10);
    freeVM = (int)(free >> 10);
    return true;
#else
    Q_UNUSED(totalMB);
    Q_UNUSED(freeMB);
    Q_UNUSED(totalVM);
    Q_UNUSED(freeVM);
    return false;
#endif
}
 
loadArray getLoadAvgs (void)
{
#if !defined(_WIN32) && !defined(Q_OS_ANDROID)
    loadArray loads {};
    if (getloadavg(loads.data(), loads.size()) != -1)
        return loads;
#endif
    return {-1, -1, -1};
}
 
bool hasUtf8(const char *str)
{
    const uchar *c = (uchar *) str;
 
    while (*c++)
    {
        // ASCII is < 0x80.
        // 0xC2..0xF4 is probably UTF-8.
        // Anything else probably ISO-8859-1 (Latin-1, Unicode)
 
        if (*c > 0xC1 && *c < 0xF5)
        {
            int bytesToCheck = 2;  // Assume  0xC2-0xDF (2 byte sequence)
 
            if (*c > 0xDF)         // Maybe   0xE0-0xEF (3 byte sequence)
                ++bytesToCheck;
            if (*c > 0xEF)         // Matches 0xF0-0xF4 (4 byte sequence)
                ++bytesToCheck;
 
            while (bytesToCheck--)
            {
                ++c;
 
                if (! *c)                    // String ended in middle
                    return false;            // Not valid UTF-8
 
                if (*c < 0x80 || *c > 0xBF)  // Bad UTF-8 sequence
                    break;                   // Keep checking in outer loop
            }
 
            if (!bytesToCheck)  // Have checked all the bytes in the sequence
                return true;    // Hooray! We found valid UTF-8!
        }
    }
 
    return false;
}
 
bool ping(const QString &host, std::chrono::milliseconds timeout)
{
#ifdef _WIN32
    QString cmd = QString("%systemroot%\\system32\\ping.exe -w %1 -n 1 %2>NUL")
                  .arg(timeout.count()) .arg(host);
 
    return myth_system(cmd, kMSDontBlockInputDevs | kMSDontDisableDrawing |
                         kMSProcessEvents) == GENERIC_EXIT_OK;
#else
    QString addrstr =
        MythCoreContext::resolveAddress(host, gCoreContext->ResolveAny, true);
    QHostAddress addr = QHostAddress(addrstr);
#if defined(__FreeBSD__) || CONFIG_DARWIN
    QString timeoutparam("-t");
#else
    // Linux, NetBSD, OpenBSD
    QString timeoutparam("-w");
#endif
    QString pingcmd =
        addr.protocol() == QAbstractSocket::IPv6Protocol ? "ping6" : "ping";
    QString cmd = QString("%1 %2 %3 -c 1  %4  >/dev/null 2>&1")
                  .arg(pingcmd, timeoutparam,
                       QString::number(duration_cast<std::chrono::seconds>(timeout).count()),
                       host);
 
    return myth_system(cmd, kMSDontBlockInputDevs | kMSDontDisableDrawing |
                         kMSProcessEvents) == GENERIC_EXIT_OK;
#endif
}
 
bool telnet(const QString &host, int port)
{
    auto *s = new MythSocket();
 
    bool connected = s->ConnectToHost(host, port);
    s->DecrRef();
 
    return connected;
}
 
long long copy(QFile &dst, QFile &src, uint block_size)
{
    uint buflen = (block_size < 1024) ? (16 * 1024) : block_size;
    char *buf = new char[buflen];
    bool odst = false;
    bool osrc = false;
 
    if (!buf)
        return -1LL;
 
    if (!dst.isWritable() && !dst.isOpen())
    {
        odst = dst.open(QIODevice::Unbuffered |
                        QIODevice::WriteOnly  |
                        QIODevice::Truncate);
    }
 
    if (!src.isReadable() && !src.isOpen())
        osrc = src.open(QIODevice::Unbuffered|QIODevice::ReadOnly);
 
    bool ok = dst.isWritable() && src.isReadable();
    long long total_bytes = 0LL;
    while (ok)
    {
        long long off = 0;
        long long rlen = src.read(buf, buflen);
        if (rlen<0)
        {
            LOG(VB_GENERAL, LOG_ERR, "read error");
            ok = false;
            break;
        }
        if (rlen==0)
            break;
 
        total_bytes += rlen;
 
        while ((rlen-off>0) && ok)
        {
            long long wlen = dst.write(buf + off, rlen - off);
            if (wlen>=0)
                off+= wlen;
            if (wlen<0)
            {
                LOG(VB_GENERAL, LOG_ERR, "write error");
                ok = false;
            }
        }
    }
    delete[] buf;
 
    if (odst)
        dst.close();
 
    if (osrc)
        src.close();
 
    return (ok) ? total_bytes : -1LL;
}
 
QString createTempFile(QString name_template, bool dir)
{
    int ret = -1;
 
#ifdef _WIN32
    char temppath[MAX_PATH] = ".";
    char tempfilename[MAX_PATH] = "";
    // if GetTempPath fails, use current dir
    GetTempPathA(MAX_PATH, temppath);
    if (GetTempFileNameA(temppath, "mth", 0, tempfilename))
    {
        if (dir)
        {
            // GetTempFileNameA creates the file, so delete it before mkdir
            unlink(tempfilename);
            ret = mkdir(tempfilename);
        }
        else
            ret = open(tempfilename, O_CREAT | O_RDWR, S_IREAD | S_IWRITE);
    }
    QString tmpFileName(tempfilename);
#else
    QByteArray safe_name_template = name_template.toLatin1();
    const char *tmp = safe_name_template.constData();
    char *ctemplate = strdup(tmp);
 
    if (dir)
    {
        ret = (mkdtemp(ctemplate)) ? 0 : -1;
    }
    else
    {
        mode_t cur_umask = umask(S_IRWXO | S_IRWXG);
        ret = mkstemp(ctemplate);
        umask(cur_umask);
    }
 
    QString tmpFileName(ctemplate);
    free(ctemplate);
#endif
 
    if (ret == -1)
    {
        LOG(VB_GENERAL, LOG_ERR, QString("createTempFile(%1), Error ")
                .arg(name_template) + ENO);
        return name_template;
    }
 
    if (!dir && (ret >= 0))
        close(ret);
 
    return tmpFileName;
}
 
bool makeFileAccessible(const QString& filename)
{
    QByteArray fname = filename.toLatin1();
    int ret = chmod(fname.constData(), 0666);
    if (ret == -1)
    {
        LOG(VB_GENERAL, LOG_ERR, QString("Unable to change permissions on file. (%1)").arg(filename));
        return false;
    }
    return true;
}
 
QString getResponse(const QString &query, const QString &def)
{
    QByteArray tmp = query.toLocal8Bit();
    std::cout << tmp.constData();
 
    tmp = def.toLocal8Bit();
    if (!def.isEmpty())
        std::cout << " [" << tmp.constData() << "]  ";
    else
        std::cout << "  ";
 
    if (!isatty(fileno(stdin)) || !isatty(fileno(stdout)))
    {
        std::cout << std::endl << "[console is not interactive, using default '"
             << tmp.constData() << "']" << std::endl;
        return def;
    }
 
    QTextStream stream(stdin);
    QString     qresponse = stream.readLine();
 
    if (qresponse.isEmpty())
        qresponse = def;
 
    return qresponse;
}
 
int intResponse(const QString &query, int def)
{
    QString str_resp = getResponse(query, QString("%1").arg(def));
    if (str_resp.isEmpty())
        return def;
    bool ok = false;
    int resp = str_resp.toInt(&ok);
    return (ok ? resp : def);
}
 
 
QString getSymlinkTarget(const QString &start_file,
                         QStringList   *intermediaries,
                         unsigned       maxLinks)
{
#if 0
    LOG(VB_GENERAL, LOG_DEBUG,
            QString("getSymlinkTarget('%1', 0x%2, %3)")
            .arg(start_file).arg((uint64_t)intermediaries,0,16)
            .arg(maxLinks));
#endif
 
    QString   link;
    QString   cur_file = start_file;
    QFileInfo fi(cur_file);
 
    if (intermediaries)
    {
        intermediaries->clear();
        intermediaries->push_back(start_file);
    }
 
    for (uint i = 0; (i <= maxLinks) && fi.isSymLink() &&
             !(link = fi.symLinkTarget()).isEmpty(); i++)
    {
        cur_file = (link[0] == '/') ?
            link : // absolute link
            fi.absoluteDir().absolutePath() + "/" + link; // relative link
 
        if (intermediaries && !intermediaries->contains(cur_file))
            intermediaries->push_back(cur_file);
 
        fi = QFileInfo(cur_file);
    }
 
#if 0
    if (intermediaries)
    {
        for (uint i = 0; i < intermediaries->size(); i++)
        {
            LOG(VB_GENERAL, LOG_DEBUG, QString("    inter%1: %2")
                    .arg(i).arg((*intermediaries)[i]));
        }
    }
 
    LOG(VB_GENERAL, LOG_DEBUG,
            QString("getSymlinkTarget() -> '%1'")
            .arg((!fi.isSymLink()) ? cur_file : QString()));
#endif
 
    return (!fi.isSymLink()) ? cur_file : QString();
}
 
bool IsMACAddress(const QString& MAC)
{
    QStringList tokens = MAC.split(':');
    if (tokens.size() != 6)
    {
        LOG(VB_NETWORK, LOG_ERR,
            QString("IsMACAddress(%1) = false, doesn't have 6 parts").arg(MAC));
        return false;
    }
 
    for (int y = 0; y < 6; y++)
    {
        if (tokens[y].isEmpty())
        {
            LOG(VB_NETWORK, LOG_ERR,
                QString("IsMACAddress(%1) = false, part #%2 is empty.")
                    .arg(MAC).arg(y));
            return false;
        }
 
        bool ok = false;
        int value = tokens[y].toInt(&ok, 16);
        if (!ok)
        {
            LOG(VB_NETWORK, LOG_ERR,
                QString("IsMACAddress(%1) = false, unable to "
                        "convert part '%2' to integer.")
                    .arg(MAC, tokens[y]));
            return false;
        }
 
        if (value > 255)
        {
            LOG(VB_NETWORK, LOG_ERR,
                QString("IsMACAddress(%1) = false, part #%2 "
                        "evaluates to %3 which is higher than 255.")
                    .arg(MAC).arg(y).arg(value));
            return false;
        }
    }
 
    LOG(VB_NETWORK, LOG_DEBUG, QString("IsMACAddress(%1) = true").arg(MAC));
    return true;
}
 
QString FileHash(const QString& filename)
{
    QFile file(filename);
    QFileInfo fileinfo(file);
    qint64 initialsize = fileinfo.size();
    quint64 hash = 0;
 
    if (initialsize == 0)
        return QString("NULL");
 
    if (file.open(QIODevice::ReadOnly))
        hash = initialsize;
    else
    {
        LOG(VB_GENERAL, LOG_ERR,
            "Error: Unable to open selected file, missing read permissions?");
        return QString("NULL");
    }
 
    file.seek(0);
    QDataStream stream(&file);
    stream.setByteOrder(QDataStream::LittleEndian);
    for (quint64 tmp = 0, i = 0; i < 65536/sizeof(tmp); i++)
    {
        stream >> tmp;
        hash += tmp;
    }
 
    file.seek(initialsize - 65536);
    for (quint64 tmp = 0, i = 0; i < 65536/sizeof(tmp); i++)
    {
        stream >> tmp;
        hash += tmp;
    }
 
    file.close();
 
    QString output = QString("%1").arg(hash, 0, 16);
    return output;
}
 
bool WakeOnLAN(const QString& MAC)
{
    std::vector<char> msg(6, static_cast<char>(0xFF));
    std::array<char,6> macaddr {};
    QStringList tokens = MAC.split(':');
 
    if (tokens.size() != 6)
    {
        LOG(VB_GENERAL, LOG_ERR,
                QString( "WakeOnLan(%1): Incorrect MAC length").arg(MAC));
        return false;
    }
 
    for (int y = 0; y < 6; y++)
    {
        bool ok = false;
        macaddr[y] = tokens[y].toInt(&ok, 16);
 
        if (!ok)
        {
            LOG(VB_GENERAL, LOG_ERR,
                    QString( "WakeOnLan(%1): Invalid MAC address").arg(MAC));
            return false;
        }
    }
 
    msg.reserve(1024);
    for (int x = 0; x < 16; x++)
        msg.insert(msg.end(), macaddr.cbegin(), macaddr.cend());
 
    LOG(VB_NETWORK, LOG_INFO,
            QString("WakeOnLan(): Sending WOL packet to %1").arg(MAC));
 
    QUdpSocket udp_socket;
    qlonglong msglen = msg.size();
    return udp_socket.writeDatagram(
        msg.data(), msglen, QHostAddress::Broadcast, 32767) == msglen;
}
 
// Wake up either by command or by MAC address
// return true = success
bool MythWakeup(const QString &wakeUpCommand, uint flags, std::chrono::seconds timeout)
{
    if (!IsMACAddress(wakeUpCommand))
        return myth_system(wakeUpCommand, flags, timeout) == 0U;
 
    return WakeOnLAN(wakeUpCommand);
}
 
bool IsPulseAudioRunning(void)
{
#ifdef _WIN32
    return false;
#else
 
#if CONFIG_DARWIN || (__FreeBSD__) || defined(__OpenBSD__)
    const char *command = "ps -ax | grep -i pulseaudio | grep -v grep > /dev/null";
#else
    const char *command = "ps ch -C pulseaudio -o pid > /dev/null";
#endif
    // Do NOT use kMSProcessEvents here, it will cause deadlock
    uint res = myth_system(command, kMSDontBlockInputDevs |
                                    kMSDontDisableDrawing);
    return (res == GENERIC_EXIT_OK);
#endif // _WIN32
}
 
bool myth_nice(int val)
{
    errno = 0;
    int ret = nice(val);
 
    if ((-1 == ret) && (0 != errno) && (val >= 0))
    {
        LOG(VB_GENERAL, LOG_ERR, "Failed to nice process" + ENO);
        return false;
    }
 
    return true;
}
 
void myth_yield(void)
{
#ifdef _POSIX_PRIORITY_SCHEDULING
    if (sched_yield()<0)
        usleep(5000);
#else
    usleep(5000);
#endif
}
 
#if defined(__linux__) && ( defined(__i386__) || defined(__ppc__) || \
                            defined(__x86_64__) || defined(__ia64__) )
 
#include <cstdio>
#include <cstdlib>
#include <cerrno>
#include <getopt.h>
#include <unistd.h>
#include <sys/ptrace.h>
#include <asm/unistd.h>
 
#if defined(__i386__)
# define NR_ioprio_set  289
# define NR_ioprio_get  290
#elif defined(__ppc__)
# define NR_ioprio_set  273
# define NR_ioprio_get  274
#elif defined(__x86_64__)
# define NR_ioprio_set  251
# define NR_ioprio_get  252
#elif defined(__ia64__)
# define NR_ioprio_set  1274
# define NR_ioprio_get  1275
#endif
 
#define IOPRIO_BITS             (16)
#define IOPRIO_CLASS_SHIFT      (13)
#define IOPRIO_PRIO_MASK        ((1UL << IOPRIO_CLASS_SHIFT) - 1)
#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
#define IOPRIO_PRIO_DATA(mask)  ((mask) & IOPRIO_PRIO_MASK)
#define IOPRIO_PRIO_VALUE(class, data)  (((class) << IOPRIO_CLASS_SHIFT) | (data))
 
enum { IOPRIO_CLASS_NONE,IOPRIO_CLASS_RT,IOPRIO_CLASS_BE,IOPRIO_CLASS_IDLE, };
enum { IOPRIO_WHO_PROCESS = 1, IOPRIO_WHO_PGRP, IOPRIO_WHO_USER, };
 
bool myth_ioprio(int val)
{
    int new_ioclass = (val < 0) ? IOPRIO_CLASS_RT :
        (val > 7) ? IOPRIO_CLASS_IDLE : IOPRIO_CLASS_BE;
    int new_iodata = (new_ioclass == IOPRIO_CLASS_BE) ? val : 0;
    int new_ioprio = IOPRIO_PRIO_VALUE(new_ioclass, new_iodata);
 
    int pid = getpid();
    int old_ioprio = syscall(NR_ioprio_get, IOPRIO_WHO_PROCESS, pid);
    if (old_ioprio == new_ioprio)
        return true;
 
    int ret = syscall(NR_ioprio_set, IOPRIO_WHO_PROCESS, pid, new_ioprio);
 
    if (-1 == ret && EPERM == errno && IOPRIO_CLASS_BE != new_ioclass)
    {
        new_iodata = (new_ioclass == IOPRIO_CLASS_RT) ? 0 : 7;
        new_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, new_iodata);
        ret = syscall(NR_ioprio_set, IOPRIO_WHO_PROCESS, pid, new_ioprio);
    }
 
    return 0 == ret;
}
 
#else
 
bool myth_ioprio(int) { return true; }
 
#endif
 
bool MythRemoveDirectory(QDir &aDir)
{
    if (!aDir.exists())//QDir::NoDotAndDotDot
        return false;
 
    QFileInfoList entries = aDir.entryInfoList(QDir::NoDotAndDotDot |
                                               QDir::Dirs | QDir::Files);
    int count = entries.size();
    bool has_err = false;
 
    for (int idx = 0; idx < count && !has_err; idx++)
    {
        QFileInfo entryInfo = entries[idx];
        QString path = entryInfo.absoluteFilePath();
        if (entryInfo.isDir())
        {
            QDir dir(path);
            has_err = MythRemoveDirectory(dir);
        }
        else
        {
            QFile file(path);
            if (!file.remove())
                has_err = true;
        }
    }
 
    if (!has_err && !aDir.rmdir(aDir.absolutePath()))
        has_err = true;
 
    return(has_err);
}
 
void setHttpProxy(void)
{
    QString       LOC = "setHttpProxy() - ";
 
    // Set http proxy for the application if specified in environment variable
    QString var(qEnvironmentVariable("http_proxy"));
    if (var.isEmpty())
        var = qEnvironmentVariable("HTTP_PROXY");  // Sadly, some OS envs are case sensitive
    if (!var.isEmpty())
    {
        if (!var.startsWith("http://"))   // i.e. just a host name
            var.prepend("http://");
 
        QUrl    url  = QUrl(var, QUrl::TolerantMode);
        QString host = url.host();
        int     port = url.port();
 
        if (port == -1)   // Parsing error
        {
            port = 0;   // The default when creating a QNetworkProxy
 
            if (telnet(host, 1080))  // Socks?
                port = 1080;
            if (telnet(host, 3128))  // Squid
                port = 3128;
            if (telnet(host, 8080))  // MS ISA
                port = 8080;
 
            LOG(VB_NETWORK, LOG_INFO, LOC +
                QString("assuming port %1 on host %2") .arg(port).arg(host));
            url.setPort(port);
        }
        else if (!ping(host, 1s))
        {
            LOG(VB_GENERAL, LOG_ERR, LOC +
                QString("cannot locate host %1").arg(host) +
                "\n\t\t\tPlease check HTTP_PROXY environment variable!");
        }
        else if (!telnet(host,port))
        {
            LOG(VB_GENERAL, LOG_ERR, LOC +
                QString("%1:%2 - cannot connect!").arg(host).arg(port) +
                "\n\t\t\tPlease check HTTP_PROXY environment variable!");
        }
 
#if 0
        LOG(VB_NETWORK, LOG_DEBUG, LOC + QString("using http://%1:%2@%3:%4")
                .arg(url.userName()).arg(url.password())
                .arg(host).arg(port));
#endif
        QNetworkProxy p =
            QNetworkProxy(QNetworkProxy::HttpCachingProxy,
                          host, port, url.userName(), url.password());
        QNetworkProxy::setApplicationProxy(p);
        return;
    }
 
    LOG(VB_NETWORK, LOG_DEBUG, LOC + "no HTTP_PROXY environment var.");
 
    // Use Qt to look for user proxy settings stored by the OS or browser:
 
    QList<QNetworkProxy> proxies;
    QNetworkProxyQuery   query(QUrl("http://www.mythtv.org"));
 
    proxies = QNetworkProxyFactory::systemProxyForQuery(query);
 
    for (const auto& p : qAsConst(proxies))
    {
        QString host = p.hostName();
        int     port = p.port();
 
        if (p.type() == QNetworkProxy::NoProxy)
            continue;
 
        if (!telnet(host, port))
        {
            LOG(VB_NETWORK, LOG_ERR, LOC +
                "failed to contact proxy host " + host);
            continue;
        }
 
        LOG(VB_NETWORK, LOG_INFO, LOC + QString("using proxy host %1:%2")
                            .arg(host).arg(port));
        QNetworkProxy::setApplicationProxy(p);
 
        // Allow sub-commands to use this proxy
        // via myth_system(command), by setting HTTP_PROXY
        QString url;
 
        if (!p.user().isEmpty())
        {
            url = "http://%1:%2@%3:%4",
            url = url.arg(p.user(), p.password());
        }
        else
        {
            url = "http://%1:%2";
        }
 
        url = url.arg(p.hostName()).arg(p.port());
        setenv("HTTP_PROXY", url.toLatin1(), 1);
        setenv("http_proxy", url.toLatin1(), 0);
 
        return;
    }
 
    LOG(VB_NETWORK, LOG_ERR, LOC + "failed to find a network proxy");
}
 
void wrapList(QStringList &list, int width)
{
    // if this is triggered, something has gone seriously wrong
    // the result won't really be usable, but at least it won't crash
    width = std::max(width, 5);
 
    for (int i = 0; i < list.size(); i++)
    {
        QString string = list.at(i);
 
        if( string.size() <= width )
            continue;
 
        QString left   = string.left(width);
        bool inserted  = false;
 
        while( !inserted && !left.endsWith(" " ))
        {
            if( string.mid(left.size(), 1) == " " )
            {
                list.replace(i, left);
                list.insert(i+1, string.mid(left.size()).trimmed());
                inserted = true;
            }
            else
            {
                left.chop(1);
                if( !left.contains(" ") )
                {
                    // Line is too long, just hyphenate it
                    list.replace(i, left + "-");
                    list.insert(i+1, string.mid(left.size()));
                    inserted = true;
                }
            }
        }
 
        if( !inserted )
        {
            left.chop(1);
            list.replace(i, left);
            list.insert(i+1, string.mid(left.size()).trimmed());
        }
    }
}
 
QString xml_indent(uint level)
{
    static QReadWriteLock s_rwLock;
    static QMap<uint,QString> s_cache;
 
    s_rwLock.lockForRead();
    QMap<uint,QString>::const_iterator it = s_cache.constFind(level);
    if (it != s_cache.constEnd())
    {
        QString tmp = *it;
        s_rwLock.unlock();
        return tmp;
    }
    s_rwLock.unlock();
 
    QString ret = "";
    for (uint i = 0; i < level; i++)
        ret += "    ";
 
    s_rwLock.lockForWrite();
    s_cache[level] = ret;
    s_rwLock.unlock();
 
    return ret;
}
 
int naturalCompare(const QString &_a, const QString &_b, Qt::CaseSensitivity caseSensitivity)
{
    // This method chops the input a and b into pieces of
    // digits and non-digits (a1.05 becomes a | 1 | . | 05)
    // and compares these pieces of a and b to each other
    // (first with first, second with second, ...).
    //
    // This is based on the natural sort order code code by Martin Pool
    // http://sourcefrog.net/projects/natsort/
    // Martin Pool agreed to license this under LGPL or GPL.
 
    // FIXME: Using toLower() to implement case insensitive comparison is
    // sub-optimal, but is needed because we compare strings with
    // localeAwareCompare(), which does not know about case sensitivity.
    // A task has been filled for this in Qt Task Tracker with ID 205990.
    // http://trolltech.com/developer/task-tracker/index_html?method=entry&id=205990
 
    QString a;
    QString b;
 
    if (caseSensitivity == Qt::CaseSensitive)
    {
        a = _a;
        b = _b;
    }
    else
    {
        a = _a.toLower();
        b = _b.toLower();
    }
 
    const QChar* currA = a.unicode(); // iterator over a
    const QChar* currB = b.unicode(); // iterator over b
 
    if (currA == currB)
    {
        return 0;
    }
 
    while (!currA->isNull() && !currB->isNull())
    {
        const QChar* begSeqA = currA; // beginning of a new character sequence of a
        const QChar* begSeqB = currB;
 
        if (currA->unicode() == QChar::ObjectReplacementCharacter)
        {
            return 1;
        }
 
        if (currB->unicode() == QChar::ObjectReplacementCharacter)
        {
            return -1;
        }
 
        if (currA->unicode() == QChar::ReplacementCharacter)
        {
            return 1;
        }
 
        if (currB->unicode() == QChar::ReplacementCharacter)
        {
            return -1;
        }
 
        // find sequence of characters ending at the first non-character
        while (!currA->isNull() && !currA->isDigit() && !currA->isPunct() &&
               !currA->isSpace())
        {
            ++currA;
        }
 
        while (!currB->isNull() && !currB->isDigit() && !currB->isPunct() &&
               !currB->isSpace())
        {
            ++currB;
        }
 
        // compare these sequences
        const QString& subA(a.mid(begSeqA - a.unicode(), currA - begSeqA));
        const QString& subB(b.mid(begSeqB - b.unicode(), currB - begSeqB));
        const int cmp = QString::localeAwareCompare(subA, subB);
 
        if (cmp != 0)
        {
            return cmp < 0 ? -1 : +1;
        }
 
        if (currA->isNull() || currB->isNull())
        {
            break;
        }
 
        // find sequence of characters ending at the first non-character
        while ((currA->isPunct() || currA->isSpace()) &&
               (currB->isPunct() || currB->isSpace()))
        {
            if (*currA != *currB)
            {
                return (*currA < *currB) ? -1 : +1;
            }
            ++currA;
            ++currB;
            if (currA->isNull() || currB->isNull())
            {
                break;
            }
        }
 
        // now some digits follow...
        if ((*currA == QLatin1Char('0')) || (*currB == QLatin1Char('0')))
        {
            // one digit-sequence starts with 0 -> assume we are in a fraction part
            // do left aligned comparison (numbers are considered left aligned)
            while (true)
            {
                if (!currA->isDigit() && !currB->isDigit())
                {
                    break;
                }
                if (!currA->isDigit())
                {
                    return +1;
                }
                if (!currB->isDigit())
                {
                    return -1;
                }
                if (*currA < *currB)
                {
                    return -1;
                }
                if (*currA > *currB)
                {
                    return + 1;
                }
                ++currA;
                ++currB;
            }
        }
        else
        {
            // No digit-sequence starts with 0 -> assume we are looking at some integer
            // do right aligned comparison.
            //
            // The longest run of digits wins. That aside, the greatest
            // value wins, but we can't know that it will until we've scanned
            // both numbers to know that they have the same magnitude.
 
            bool isFirstRun = true;
            int weight = 0;
 
            while (true)
            {
                if (!currA->isDigit() && !currB->isDigit())
                {
                    if (weight != 0)
                    {
                        return weight;
                    }
                    break;
                }
                if (!currA->isDigit())
                {
                    if (isFirstRun)
                    {
                        return *currA < *currB ? -1 : +1;
                    }
                    return -1;
                }
                if (!currB->isDigit())
                {
                    if (isFirstRun)
                    {
                        return *currA < *currB ? -1 : +1;
                    }
                    return +1;
                }
                if ((*currA < *currB) && (weight == 0))
                {
                    weight = -1;
                }
                else if ((*currA > *currB) && (weight == 0))
                {
                    weight = + 1;
                }
                ++currA;
                ++currB;
                isFirstRun = false;
            }
        }
    }
 
    if (currA->isNull() && currB->isNull())
    {
        return 0;
    }
 
    return currA->isNull() ? -1 : + 1;
}
 
QString MythFormatTime(std::chrono::milliseconds msecs, const QString& fmt)
{
    return QTime::fromMSecsSinceStartOfDay(msecs.count()).toString(fmt);
}
 
/*
 * States for the command line parser.
 */
enum states {
    START,     // No current token.
    INTEXT,    // Collecting token text.
    INSQUOTE,  // Collecting token, inside single quotes.
    INDQUOTE,  // Collecting token, inside double quotes.
    ESCTEXT,   // Saw backslash. Returns to generic text.
    ESCSQUOTE, // Saw backslash. Returns to single quotes.
    ESCDQUOTE, // Saw backslash. Returns to double quotes.
};
 
/*
 * Parse a string into separate tokens. This function understands
 * quoting and the escape character.
 */
QStringList MythSplitCommandString(const QString &line)
{
    QStringList fields;
    states state = START;
    int tokenStart = -1;
 
    for (int i = 0; i < line.size(); i++)
    {
        const QChar c = line.at(i);
 
        switch (state) {
          case START:
            tokenStart = i;
            if      (c.isSpace()) break;
            if      (c == '\'') state = INSQUOTE;
            else if (c == '\"') state = INDQUOTE;
            else if (c == '\\') state = ESCTEXT;
            else                state = INTEXT;
            break;
          case INTEXT:
            if (c.isSpace()) {
                fields += line.mid(tokenStart, i - tokenStart);
                state = START;
                break;
            }
            else if (c == '\'') state = INSQUOTE;
            else if (c == '\"') state = INDQUOTE;
            else if (c == '\\') state = ESCTEXT;
            break;
          case INSQUOTE:
            if      (c == '\'') state = INTEXT;
            else if (c == '\\') state = ESCSQUOTE;
            break;
          case INDQUOTE:
            if      (c == '\"') state = INTEXT;
            else if (c == '\\') state = ESCDQUOTE;
            break;
          case ESCTEXT:   state = INTEXT;   break;
          case ESCSQUOTE: state = INSQUOTE; break;
          case ESCDQUOTE: state = INDQUOTE; break;
        }
    }
 
    if (state != START)
        fields += line.mid(tokenStart);
    return fields;
}
 
/* vim: set expandtab tabstop=4 shiftwidth=4: */