/*
 * Copyright 2018 Google LLC
 * SPDX-License-Identifier: MIT
 */

#include "VirtioGpuPipeStream.h"

#include <errno.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>

#include <cstring>
#include <string>

#include "VirtGpu.h"
#include "util/log.h"

static const size_t kTransferBufferSize = (1048576);

static const size_t kReadSize = 512 * 1024;
static const size_t kWriteOffset = kReadSize;

VirtioGpuPipeStream::VirtioGpuPipeStream(size_t bufSize, int32_t descriptor)
    : IOStream(bufSize),
      m_fd(descriptor),
      m_virtio_mapped(nullptr),
      m_bufsize(bufSize),
      m_buf(nullptr),
      m_writtenPos(0) {}

VirtioGpuPipeStream::~VirtioGpuPipeStream() { free(m_buf); }

bool VirtioGpuPipeStream::valid() { return m_device != nullptr; }

int VirtioGpuPipeStream::getRendernodeFd() {
    if (m_device == nullptr) {
        return -1;
    }
    return m_device->getDeviceHandle();
}

int VirtioGpuPipeStream::connect(const char* serviceName) {
    if (!m_device) {
        m_device.reset(createPlatformVirtGpuDevice(kCapsetNone, m_fd));
        if (!m_device) {
            mesa_loge("Failed to create VirtioGpuPipeStream VirtGpuDevice.");
            return -1;
        }

        m_resource = m_device->createResource(/*width=*/kTransferBufferSize,
                                              /*height=*/1,
                                              /*stride=*/kTransferBufferSize,
                                              /*size=*/kTransferBufferSize, VIRGL_FORMAT_R8_UNORM,
                                              PIPE_BUFFER, VIRGL_BIND_CUSTOM);
        if (!m_resource) {
            mesa_loge("Failed to create VirtioGpuPipeStream resource.");
            return -1;
        }

        m_resourceMapping = m_resource->createMapping();
        if (!m_resourceMapping) {
            mesa_loge("Failed to create VirtioGpuPipeStream resource mapping.");
            return -1;
        }

        m_virtio_mapped = m_resourceMapping->asRawPtr();
        if (!m_virtio_mapped) {
            mesa_loge("Failed to create VirtioGpuPipeStream resource mapping ptr.");
            return -1;
        }
    }

    wait();

    if (serviceName) {
        writeFully(serviceName, strlen(serviceName) + 1);
    } else {
        static const char kPipeString[] = "pipe:opengles";
        std::string pipeStr(kPipeString);
        writeFully(kPipeString, sizeof(kPipeString));
    }

    return 0;
}

uint64_t VirtioGpuPipeStream::processPipeInit() {
    connect("pipe:GLProcessPipe");
    int32_t confirmInt = 100;
    writeFully(&confirmInt, sizeof(confirmInt));
    uint64_t res;
    readFully(&res, sizeof(res));
    return res;
}

void* VirtioGpuPipeStream::allocBuffer(size_t minSize) {
    size_t allocSize = (m_bufsize < minSize ? minSize : m_bufsize);
    if (!m_buf) {
        m_buf = (unsigned char*)malloc(allocSize);
    } else if (m_bufsize < allocSize) {
        unsigned char* p = (unsigned char*)realloc(m_buf, allocSize);
        if (p != NULL) {
            m_buf = p;
            m_bufsize = allocSize;
        } else {
            mesa_loge("realloc (%zu) failed\n", allocSize);
            free(m_buf);
            m_buf = NULL;
            m_bufsize = 0;
        }
    }

    return m_buf;
}

int VirtioGpuPipeStream::commitBuffer(size_t size) {
    if (size == 0) return 0;
    return writeFully(m_buf, size);
}

int VirtioGpuPipeStream::writeFully(const void* buf, size_t len) {
    // DBG(">> VirtioGpuPipeStream::writeFully %d\n", len);
    if (!valid()) return -1;
    if (!buf) {
        if (len > 0) {
            // If len is non-zero, buf must not be NULL. Otherwise the pipe would be
            // in a corrupted state, which is lethal for the emulator.
            mesa_loge(
                "VirtioGpuPipeStream::writeFully failed, buf=NULL, len %zu,"
                " lethal error, exiting",
                len);
            abort();
        }
        return 0;
    }

    size_t res = len;
    int retval = 0;

    while (res > 0) {
        ssize_t stat = transferToHost((const char*)(buf) + (len - res), res);
        if (stat > 0) {
            res -= stat;
            continue;
        }
        if (stat == 0) { /* EOF */
            mesa_loge("VirtioGpuPipeStream::writeFully failed: premature EOF\n");
            retval = -1;
            break;
        }
        if (errno == EAGAIN) {
            continue;
        }
        retval = stat;
        mesa_loge("VirtioGpuPipeStream::writeFully failed: %s, lethal error, exiting.\n",
                  strerror(errno));
        abort();
    }
    // DBG("<< VirtioGpuPipeStream::writeFully %d\n", len );
    return retval;
}

const unsigned char* VirtioGpuPipeStream::readFully(void* buf, size_t len) {
    flush();

    if (!valid()) return NULL;
    if (!buf) {
        if (len > 0) {
            // If len is non-zero, buf must not be NULL. Otherwise the pipe would be
            // in a corrupted state, which is lethal for the emulator.
            mesa_loge(
                "VirtioGpuPipeStream::readFully failed, buf=NULL, len %zu, lethal"
                " error, exiting.",
                len);
            abort();
        }
    }

    size_t res = len;
    while (res > 0) {
        ssize_t stat = transferFromHost((char*)(buf) + len - res, res);
        if (stat == 0) {
            // client shutdown;
            return NULL;
        } else if (stat < 0) {
            if (errno == EAGAIN) {
                continue;
            } else {
                mesa_loge(
                    "VirtioGpuPipeStream::readFully failed (buf %p, len %zu"
                    ", res %zu): %s, lethal error, exiting.",
                    buf, len, res, strerror(errno));
                abort();
            }
        } else {
            res -= stat;
        }
    }
    // DBG("<< VirtioGpuPipeStream::readFully %d\n", len);
    return (const unsigned char*)buf;
}

const unsigned char* VirtioGpuPipeStream::commitBufferAndReadFully(size_t writeSize,
                                                                   void* userReadBufPtr,
                                                                   size_t totalReadSize) {
    return commitBuffer(writeSize) ? nullptr : readFully(userReadBufPtr, totalReadSize);
}

const unsigned char* VirtioGpuPipeStream::read(void* buf, size_t* inout_len) {
    // DBG(">> VirtioGpuPipeStream::read %d\n", *inout_len);
    if (!valid()) return NULL;
    if (!buf) {
        mesa_loge("VirtioGpuPipeStream::read failed, buf=NULL");
        return NULL;  // do not allow NULL buf in that implementation
    }

    int n = recv(buf, *inout_len);

    if (n > 0) {
        *inout_len = n;
        return (const unsigned char*)buf;
    }

    // DBG("<< VirtioGpuPipeStream::read %d\n", *inout_len);
    return NULL;
}

int VirtioGpuPipeStream::recv(void* buf, size_t len) {
    if (!valid()) return -EINVAL;
    char* p = (char*)buf;
    int ret = 0;
    while (len > 0) {
        int res = transferFromHost(p, len);
        if (res > 0) {
            p += res;
            ret += res;
            len -= res;
            continue;
        }
        if (res == 0) { /* EOF */
            break;
        }
        if (errno != EAGAIN) {
            continue;
        }

        /* A real error */
        if (ret == 0) ret = -1;
        break;
    }
    return ret;
}

void VirtioGpuPipeStream::wait() {
    int ret = m_resource->wait();
    if (ret) {
        mesa_loge("VirtioGpuPipeStream: DRM_IOCTL_VIRTGPU_WAIT failed with %d (%s)\n", errno,
                  strerror(errno));
    }

    m_writtenPos = 0;
}

ssize_t VirtioGpuPipeStream::transferToHost(const void* buffer, size_t len) {
    size_t todo = len;
    size_t done = 0;
    int ret = EAGAIN;

    unsigned char* virtioPtr = m_virtio_mapped;

    const unsigned char* readPtr = reinterpret_cast<const unsigned char*>(buffer);

    while (done < len) {
        size_t toXfer = todo > kTransferBufferSize ? kTransferBufferSize : todo;

        if (toXfer > (kTransferBufferSize - m_writtenPos)) {
            wait();
        }

        memcpy(virtioPtr + m_writtenPos, readPtr, toXfer);

        ret = m_resource->transferToHost(m_writtenPos, toXfer);
        if (ret) {
            mesa_loge("VirtioGpuPipeStream: failed to transferToHost() with errno %d (%s)\n", errno,
                      strerror(errno));
            return (ssize_t)ret;
        }

        done += toXfer;
        readPtr += toXfer;
        todo -= toXfer;
        m_writtenPos += toXfer;
    }

    return len;
}

ssize_t VirtioGpuPipeStream::transferFromHost(void* buffer, size_t len) {
    size_t todo = len;
    size_t done = 0;
    int ret = EAGAIN;

    const unsigned char* virtioPtr = m_virtio_mapped;
    unsigned char* readPtr = reinterpret_cast<unsigned char*>(buffer);

    if (m_writtenPos) {
        wait();
    }

    while (done < len) {
        size_t toXfer = todo > kTransferBufferSize ? kTransferBufferSize : todo;

        ret = m_resource->transferFromHost(0, toXfer);
        if (ret) {
            mesa_loge("VirtioGpuPipeStream: failed to transferFromHost() with errno %d (%s)\n",
                      errno, strerror(errno));
            return (ssize_t)ret;
        }

        wait();

        memcpy(readPtr, virtioPtr, toXfer);

        done += toXfer;
        readPtr += toXfer;
        todo -= toXfer;
    }

    return len;
}