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** Copyright (C) 2016 The Qt Company Ltd.
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****************************************************************************/

#include "qopenglprogrambinarycache_p.h"
#include <QOpenGLContext>
#include <QOpenGLExtraFunctions>
#include <QSysInfo>
#include <QStandardPaths>
#include <QDir>
#include <QSaveFile>
#include <QCoreApplication>
#include <QLoggingCategory>
#include <QCryptographicHash>

#ifdef Q_OS_UNIX
#include <sys/mman.h>
#include <private/qcore_unix_p.h>
#endif

QT_BEGIN_NAMESPACE

Q_LOGGING_CATEGORY(lcOpenGLProgramDiskCache, "qt.opengl.diskcache")

#ifndef GL_CONTEXT_LOST
#define GL_CONTEXT_LOST                   0x0507
#endif

#ifndef GL_PROGRAM_BINARY_LENGTH
#define GL_PROGRAM_BINARY_LENGTH          0x8741
#endif

#ifndef GL_NUM_PROGRAM_BINARY_FORMATS
#define GL_NUM_PROGRAM_BINARY_FORMATS     0x87FE
#endif

const quint32 BINSHADER_MAGIC = 0x5174;
const quint32 BINSHADER_VERSION = 0x3;
const quint32 BINSHADER_QTVERSION = QT_VERSION;

namespace {
struct GLEnvInfo
{
    GLEnvInfo();

    QByteArray glvendor;
    QByteArray glrenderer;
    QByteArray glversion;
};
}

GLEnvInfo::GLEnvInfo()
{
    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    Q_ASSERT(ctx);
    QOpenGLFunctions *f = ctx->functions();
    const char *vendor = reinterpret_cast<const char *>(f->glGetString(GL_VENDOR));
    const char *renderer = reinterpret_cast<const char *>(f->glGetString(GL_RENDERER));
    const char *version = reinterpret_cast<const char *>(f->glGetString(GL_VERSION));
    if (vendor)
        glvendor = QByteArray(vendor);
    if (renderer)
        glrenderer = QByteArray(renderer);
    if (version)
        glversion = QByteArray(version);
}

QByteArray QOpenGLProgramBinaryCache::ProgramDesc::cacheKey() const
{
    QCryptographicHash keyBuilder(QCryptographicHash::Sha1);
    for (const QOpenGLProgramBinaryCache::ShaderDesc &shader : shaders)
        keyBuilder.addData(shader.source);

    return keyBuilder.result().toHex();
}

static inline bool qt_ensureWritableDir(const QString &name)
{
    QDir::root().mkpath(name);
    return QFileInfo(name).isWritable();
}

QOpenGLProgramBinaryCache::QOpenGLProgramBinaryCache()
    : m_cacheWritable(false)
{
    const QString subPath = QLatin1String("/qtshadercache-") + QSysInfo::buildAbi() + QLatin1Char('/');
    const QString sharedCachePath = QStandardPaths::writableLocation(QStandardPaths::GenericCacheLocation);
    m_globalCacheDir = sharedCachePath + subPath;
    m_localCacheDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + subPath;

    if (!sharedCachePath.isEmpty()) {
        m_currentCacheDir = m_globalCacheDir;
        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
    }
    if (!m_cacheWritable) {
        m_currentCacheDir = m_localCacheDir;
        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
    }

    qCDebug(lcOpenGLProgramDiskCache, "Cache location '%s' writable = %d", qPrintable(m_currentCacheDir), m_cacheWritable);
}

QString QOpenGLProgramBinaryCache::cacheFileName(const QByteArray &cacheKey) const
{
    return m_currentCacheDir + QString::fromUtf8(cacheKey);
}

#define BASE_HEADER_SIZE (int(4 * sizeof(quint32)))
#define FULL_HEADER_SIZE(stringsSize) (BASE_HEADER_SIZE + 12 + stringsSize + 8)
#define PADDING_SIZE(fullHeaderSize) (((fullHeaderSize + 3) & ~3) - fullHeaderSize)

static inline quint32 readUInt(const uchar **p)
{
    quint32 v;
    memcpy(&v, *p, sizeof(quint32));
    *p += sizeof(quint32);
    return v;
}

static inline QByteArray readStr(const uchar **p)
{
    quint32 len = readUInt(p);
    QByteArray ba = QByteArray::fromRawData(reinterpret_cast<const char *>(*p), len);
    *p += len;
    return ba;
}

bool QOpenGLProgramBinaryCache::verifyHeader(const QByteArray &buf) const
{
    if (buf.size() < BASE_HEADER_SIZE) {
        qCDebug(lcOpenGLProgramDiskCache, "Cached size too small");
        return false;
    }
    const uchar *p = reinterpret_cast<const uchar *>(buf.constData());
    if (readUInt(&p) != BINSHADER_MAGIC) {
        qCDebug(lcOpenGLProgramDiskCache, "Magic does not match");
        return false;
    }
    if (readUInt(&p) != BINSHADER_VERSION) {
        qCDebug(lcOpenGLProgramDiskCache, "Version does not match");
        return false;
    }
    if (readUInt(&p) != BINSHADER_QTVERSION) {
        qCDebug(lcOpenGLProgramDiskCache, "Qt version does not match");
        return false;
    }
    if (readUInt(&p) != sizeof(quintptr)) {
        qCDebug(lcOpenGLProgramDiskCache, "Architecture does not match");
        return false;
    }
    return true;
}

bool QOpenGLProgramBinaryCache::setProgramBinary(uint programId, uint blobFormat, const void *p, uint blobSize)
{
    QOpenGLContext *context = QOpenGLContext::currentContext();
    QOpenGLExtraFunctions *funcs = context->extraFunctions();
    while (true) {
        GLenum error = funcs->glGetError();
        if (error == GL_NO_ERROR || error == GL_CONTEXT_LOST)
            break;
    }
#if defined(QT_OPENGL_ES_2)
    if (context->isOpenGLES() && context->format().majorVersion() < 3) {
        initializeProgramBinaryOES(context);
        programBinaryOES(programId, blobFormat, p, blobSize);
    } else
#endif
    funcs->glProgramBinary(programId, blobFormat, p, blobSize);

    GLenum err = funcs->glGetError();
    if (err != GL_NO_ERROR) {
        qCDebug(lcOpenGLProgramDiskCache, "Program binary failed to load for program %u, size %d, "
                                  "format 0x%x, err = 0x%x",
                programId, blobSize, blobFormat, err);
        return false;
    }
    GLint linkStatus = 0;
    funcs->glGetProgramiv(programId, GL_LINK_STATUS, &linkStatus);
    if (linkStatus != GL_TRUE) {
        qCDebug(lcOpenGLProgramDiskCache, "Program binary failed to load for program %u, size %d, "
                                  "format 0x%x, linkStatus = 0x%x, err = 0x%x",
                programId, blobSize, blobFormat, linkStatus, err);
        return false;
    }

    qCDebug(lcOpenGLProgramDiskCache, "Program binary set for program %u, size %d, format 0x%x, err = 0x%x",
            programId, blobSize, blobFormat, err);
    return true;
}

#ifdef Q_OS_UNIX
class FdWrapper
{
public:
    FdWrapper(const QString &fn)
        : ptr(MAP_FAILED)
    {
        fd = qt_safe_open(QFile::encodeName(fn).constData(), O_RDONLY);
    }
    ~FdWrapper()
    {
        if (ptr != MAP_FAILED)
            munmap(ptr, mapSize);
        if (fd != -1)
            qt_safe_close(fd);
    }
    bool map()
    {
        off_t offs = lseek(fd, 0, SEEK_END);
        if (offs == (off_t) -1) {
            qErrnoWarning(errno, "lseek failed for program binary");
            return false;
        }
        mapSize = static_cast<size_t>(offs);
        ptr = mmap(nullptr, mapSize, PROT_READ, MAP_SHARED, fd, 0);
        return ptr != MAP_FAILED;
    }

    int fd;
    void *ptr;
    size_t mapSize;
};
#endif

class DeferredFileRemove
{
public:
    DeferredFileRemove(const QString &fn)
        : fn(fn),
          active(false)
    {
    }
    ~DeferredFileRemove()
    {
        if (active)
            QFile(fn).remove();
    }
    void setActive()
    {
        active = true;
    }

    QString fn;
    bool active;
};

bool QOpenGLProgramBinaryCache::load(const QByteArray &cacheKey, uint programId)
{
    QMutexLocker lock(&m_mutex);
    if (const MemCacheEntry *e = m_memCache.object(cacheKey))
        return setProgramBinary(programId, e->format, e->blob.constData(), e->blob.size());

    QByteArray buf;
    const QString fn = cacheFileName(cacheKey);
    DeferredFileRemove undertaker(fn);
#ifdef Q_OS_UNIX
    FdWrapper fdw(fn);
    if (fdw.fd == -1)
        return false;
    char header[BASE_HEADER_SIZE];
    qint64 bytesRead = qt_safe_read(fdw.fd, header, BASE_HEADER_SIZE);
    if (bytesRead == BASE_HEADER_SIZE)
        buf = QByteArray::fromRawData(header, BASE_HEADER_SIZE);
#else
    QFile f(fn);
    if (!f.open(QIODevice::ReadOnly))
        return false;
    buf = f.read(BASE_HEADER_SIZE);
#endif

    if (!verifyHeader(buf)) {
        undertaker.setActive();
        return false;
    }

    const uchar *p;
#ifdef Q_OS_UNIX
    if (!fdw.map()) {
        undertaker.setActive();
        return false;
    }
    p = static_cast<const uchar *>(fdw.ptr) + BASE_HEADER_SIZE;
#else
    buf = f.readAll();
    p = reinterpret_cast<const uchar *>(buf.constData());
#endif

    GLEnvInfo info;

    QByteArray vendor = readStr(&p);
    if (vendor != info.glvendor) {
        // readStr returns non-null terminated strings just pointing to inside
        // 'p' so must print these via the stream qCDebug and not constData().
        qCDebug(lcOpenGLProgramDiskCache) << "GL_VENDOR does not match" << vendor << info.glvendor;
        undertaker.setActive();
        return false;
    }
    QByteArray renderer = readStr(&p);
    if (renderer != info.glrenderer) {
        qCDebug(lcOpenGLProgramDiskCache) << "GL_RENDERER does not match" << renderer << info.glrenderer;
        undertaker.setActive();
        return false;
    }
    QByteArray version = readStr(&p);
    if (version != info.glversion) {
        qCDebug(lcOpenGLProgramDiskCache) <<  "GL_VERSION does not match" << version << info.glversion;
        undertaker.setActive();
        return false;
    }

    quint32 blobFormat = readUInt(&p);
    quint32 blobSize = readUInt(&p);

    p += PADDING_SIZE(FULL_HEADER_SIZE(vendor.size() + renderer.size() + version.size()));

    return setProgramBinary(programId, blobFormat, p, blobSize)
        && m_memCache.insert(cacheKey, new MemCacheEntry(p, blobSize, blobFormat));
}

static inline void writeUInt(uchar **p, quint32 value)
{
    memcpy(*p, &value, sizeof(quint32));
    *p += sizeof(quint32);
}

static inline void writeStr(uchar **p, const QByteArray &str)
{
    writeUInt(p, str.size());
    memcpy(*p, str.constData(), str.size());
    *p += str.size();
}

static inline bool writeFile(const QString &filename, const QByteArray &data)
{
#if QT_CONFIG(temporaryfile)
    QSaveFile f(filename);
    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
        f.write(data);
        if (f.commit())
            return true;
    }
#else
    QFile f(filename);
    if (f.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
        if (f.write(data) == data.length())
            return true;
    }
#endif
    return false;
}

void QOpenGLProgramBinaryCache::save(const QByteArray &cacheKey, uint programId)
{
    if (!m_cacheWritable)
        return;

    GLEnvInfo info;

    QOpenGLContext *context = QOpenGLContext::currentContext();
    QOpenGLExtraFunctions *funcs = context->extraFunctions();
    GLint blobSize = 0;
    while (true) {
        GLenum error = funcs->glGetError();
        if (error == GL_NO_ERROR || error == GL_CONTEXT_LOST)
            break;
    }
    funcs->glGetProgramiv(programId, GL_PROGRAM_BINARY_LENGTH, &blobSize);

    const int headerSize = FULL_HEADER_SIZE(info.glvendor.size() + info.glrenderer.size() + info.glversion.size());

    // Add padding to make the blob start 4-byte aligned in order to support
    // OpenGL implementations on ARM that choke on non-aligned pointers passed
    // to glProgramBinary.
    const int paddingSize = PADDING_SIZE(headerSize);

    const int totalSize = headerSize + paddingSize + blobSize;

    qCDebug(lcOpenGLProgramDiskCache, "Program binary is %d bytes, err = 0x%x, total %d", blobSize, funcs->glGetError(), totalSize);
    if (!blobSize)
        return;

    QByteArray blob(totalSize, Qt::Uninitialized);
    uchar *p = reinterpret_cast<uchar *>(blob.data());

    writeUInt(&p, BINSHADER_MAGIC);
    writeUInt(&p, BINSHADER_VERSION);
    writeUInt(&p, BINSHADER_QTVERSION);
    writeUInt(&p, sizeof(quintptr));

    writeStr(&p, info.glvendor);
    writeStr(&p, info.glrenderer);
    writeStr(&p, info.glversion);

    quint32 blobFormat = 0;
    uchar *blobFormatPtr = p;
    writeUInt(&p, blobFormat);
    writeUInt(&p, blobSize);

    for (int i = 0; i < paddingSize; ++i)
        *p++ = 0;

    GLint outSize = 0;
#if defined(QT_OPENGL_ES_2)
    if (context->isOpenGLES() && context->format().majorVersion() < 3) {
        QMutexLocker lock(&m_mutex);
        initializeProgramBinaryOES(context);
        getProgramBinaryOES(programId, blobSize, &outSize, &blobFormat, p);
    } else
#endif
    funcs->glGetProgramBinary(programId, blobSize, &outSize, &blobFormat, p);
    if (blobSize != outSize) {
        qCDebug(lcOpenGLProgramDiskCache, "glGetProgramBinary returned size %d instead of %d", outSize, blobSize);
        return;
    }

    writeUInt(&blobFormatPtr, blobFormat);

    QString filename = cacheFileName(cacheKey);
    bool ok = writeFile(filename, blob);
    if (!ok && m_currentCacheDir == m_globalCacheDir) {
        m_currentCacheDir = m_localCacheDir;
        m_cacheWritable = qt_ensureWritableDir(m_currentCacheDir);
        qCDebug(lcOpenGLProgramDiskCache, "Cache location changed to '%s' writable = %d",
                qPrintable(m_currentCacheDir), m_cacheWritable);
        if (m_cacheWritable) {
            filename = cacheFileName(cacheKey);
            ok = writeFile(filename, blob);
        }
    }
    if (!ok)
        qCDebug(lcOpenGLProgramDiskCache, "Failed to write %s to shader cache", qPrintable(filename));
}

#if defined(QT_OPENGL_ES_2)
void QOpenGLProgramBinaryCache::initializeProgramBinaryOES(QOpenGLContext *context)
{
    if (m_programBinaryOESInitialized)
        return;
    m_programBinaryOESInitialized = true;

    Q_ASSERT(context);
    getProgramBinaryOES = (void (QOPENGLF_APIENTRYP)(GLuint program, GLsizei bufSize, GLsizei *length, GLenum *binaryFormat, GLvoid *binary))context->getProcAddress("glGetProgramBinaryOES");
    programBinaryOES = (void (QOPENGLF_APIENTRYP)(GLuint program, GLenum binaryFormat, const GLvoid *binary, GLint length))context->getProcAddress("glProgramBinaryOES");
}
#endif

QOpenGLProgramBinarySupportCheck::QOpenGLProgramBinarySupportCheck(QOpenGLContext *context)
    : QOpenGLSharedResource(context->shareGroup()),
      m_supported(false)
{
    if (QCoreApplication::testAttribute(Qt::AA_DisableShaderDiskCache)) {
        qCDebug(lcOpenGLProgramDiskCache, "Shader cache disabled via app attribute");
        return;
    }
    if (qEnvironmentVariableIntValue("QT_DISABLE_SHADER_DISK_CACHE")) {
        qCDebug(lcOpenGLProgramDiskCache, "Shader cache disabled via env var");
        return;
    }

    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    if (ctx) {
        if (ctx->isOpenGLES()) {
            qCDebug(lcOpenGLProgramDiskCache, "OpenGL ES v%d context", ctx->format().majorVersion());
            if (ctx->format().majorVersion() >= 3) {
                m_supported = true;
            } else {
                const bool hasExt = ctx->hasExtension("GL_OES_get_program_binary");
                qCDebug(lcOpenGLProgramDiskCache, "GL_OES_get_program_binary support = %d", hasExt);
                if (hasExt)
                    m_supported = true;
            }
        } else {
            const bool hasExt = ctx->hasExtension("GL_ARB_get_program_binary");
            qCDebug(lcOpenGLProgramDiskCache, "GL_ARB_get_program_binary support = %d", hasExt);
            if (hasExt)
                m_supported = true;
        }
        if (m_supported) {
            GLint fmtCount = 0;
            ctx->functions()->glGetIntegerv(GL_NUM_PROGRAM_BINARY_FORMATS, &fmtCount);
            qCDebug(lcOpenGLProgramDiskCache, "Supported binary format count = %d", fmtCount);
            m_supported = fmtCount > 0;
        }
    }
    qCDebug(lcOpenGLProgramDiskCache, "Shader cache supported = %d", m_supported);
}

QT_END_NAMESPACE
