Adds an interface method to the FrameCapture class to get the device
display info (device address and device display id) for each display of
the graphics device that is captured.

Also adds functions to the API implementing this functionality for X11
in variants with and without DRM (the non-DRM version is rather limited
and may not work for more complex setups) as well as some helper
functions to make it easier for plugins to implement this and avoid code
duplication.

Implements the new interface method for the two built-in plugins
(mjpeg-fallback and gst-plugin).

Signed-off-by: Lukáš Hrázký <lhra...@redhat.com>
Acked-by: Jonathon Jongsma <jjong...@redhat.com>
---
 configure.ac                                  |   2 +
 include/spice-streaming-agent/Makefile.am     |   2 +
 .../spice-streaming-agent/display-info.hpp    |  52 +++
 .../spice-streaming-agent/frame-capture.hpp   |  13 +
 .../x11-display-info.hpp                      |  57 ++++
 src/Makefile.am                               |   7 +
 src/display-info.cpp                          | 101 ++++++
 src/gst-plugin.cpp                            |  14 +
 src/mjpeg-fallback.cpp                        |  17 +-
 src/spice-streaming-agent.cpp                 |  13 +
 src/unittests/Makefile.am                     |   6 +
 src/utils.cpp                                 |  46 +++
 src/utils.hpp                                 |   4 +
 src/x11-display-info.cpp                      | 302 ++++++++++++++++++
 14 files changed, 634 insertions(+), 2 deletions(-)
 create mode 100644 include/spice-streaming-agent/display-info.hpp
 create mode 100644 include/spice-streaming-agent/x11-display-info.hpp
 create mode 100644 src/display-info.cpp
 create mode 100644 src/utils.cpp
 create mode 100644 src/x11-display-info.cpp

diff --git a/configure.ac b/configure.ac
index e66e6d8..fd18efe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,8 +34,10 @@ SPICE_PROTOCOL_MIN_VER=0.12.14
 PKG_CHECK_MODULES([SPICE_PROTOCOL], [spice-protocol >= 
$SPICE_PROTOCOL_MIN_VER])
 AC_SUBST([SPICE_PROTOCOL_MIN_VER])
 
+PKG_CHECK_MODULES(DRM, libdrm)
 PKG_CHECK_MODULES(X11, x11)
 PKG_CHECK_MODULES(XFIXES, xfixes)
+PKG_CHECK_MODULES(XRANDR, xrandr)
 
 PKG_CHECK_MODULES(JPEG, libjpeg, , [
     AC_CHECK_LIB(jpeg, jpeg_destroy_decompress,
diff --git a/include/spice-streaming-agent/Makefile.am 
b/include/spice-streaming-agent/Makefile.am
index bcd679b..96c1a57 100644
--- a/include/spice-streaming-agent/Makefile.am
+++ b/include/spice-streaming-agent/Makefile.am
@@ -1,8 +1,10 @@
 NULL =
 public_includedir = $(includedir)/spice-streaming-agent
 public_include_HEADERS = \
+       display-info.hpp \
        error.hpp \
        frame-capture.hpp \
        plugin.hpp \
+       x11-display-info.hpp \
        $(NULL)
 
diff --git a/include/spice-streaming-agent/display-info.hpp 
b/include/spice-streaming-agent/display-info.hpp
new file mode 100644
index 0000000..f16212b
--- /dev/null
+++ b/include/spice-streaming-agent/display-info.hpp
@@ -0,0 +1,52 @@
+/* \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#ifndef SPICE_STREAMING_AGENT_DISPLAY_INFO_HPP
+#define SPICE_STREAMING_AGENT_DISPLAY_INFO_HPP
+
+#include <vector>
+#include <string>
+
+
+namespace spice __attribute__ ((visibility ("default"))) {
+namespace streaming_agent {
+
+/**
+ * Lists graphics cards listed in the DRM sybsystem in /sys/class/drm.
+ * Throws an instance of Error in case of an I/O error.
+ *
+ * @return a vector of paths of all graphics cards present in /sys/class/drm
+ */
+std::vector<std::string> list_cards();
+
+/**
+ * Reads a single number in hex format from a file.
+ * Throws an instance of Error in case of an I/O or parsing error.
+ *
+ * @param path the path to the file
+ * @return the number parsed from the file
+ */
+uint32_t read_hex_number_from_file(const std::string &path);
+
+/**
+ * Resolves any symlinks and then extracts the PCI path from the canonical path
+ * to a card. Returns the path in the following format:
+ * "pci/<DOMAIN>/<SLOT>.<FUNCTION>/.../<SLOT>.<FUNCTION>"
+ *
+ * <DOMAIN> is the PCI domain, followed by <SLOT>.<FUNCTION> of any PCI bridges
+ * in the chain leading to the device. The last <SLOT>.<FUNCTION> is the
+ * graphics device. All of <DOMAIN>, <SLOT>, <FUNCTION> are hexadecimal numbers
+ * with the following number of digits:
+ *   <DOMAIN>: 4
+ *   <SLOT>: 2
+ *   <FUNCTION>: 1
+ *
+ * @param device_path the path to the card
+ * @return the device address
+ */
+std::string get_device_address(const std::string &card_path);
+
+}} // namespace spice::streaming_agent
+
+#endif // SPICE_STREAMING_AGENT_DISPLAY_INFO_HPP
diff --git a/include/spice-streaming-agent/frame-capture.hpp 
b/include/spice-streaming-agent/frame-capture.hpp
index 51a2987..c244fb9 100644
--- a/include/spice-streaming-agent/frame-capture.hpp
+++ b/include/spice-streaming-agent/frame-capture.hpp
@@ -6,7 +6,11 @@
  */
 #ifndef SPICE_STREAMING_AGENT_FRAME_CAPTURE_HPP
 #define SPICE_STREAMING_AGENT_FRAME_CAPTURE_HPP
+
+#include <cstdint>
 #include <cstdio>
+#include <string>
+#include <vector>
 
 #include <spice/enums.h>
 
@@ -29,6 +33,13 @@ struct FrameInfo
     bool stream_start;
 };
 
+struct DeviceDisplayInfo
+{
+    uint32_t stream_id;
+    std::string device_address;
+    uint32_t device_display_id;
+};
+
 /*!
  * Pure base class implementing the frame capture
  */
@@ -52,6 +63,8 @@ public:
      * Get video codec used to encode last frame
      */
     virtual SpiceVideoCodecType VideoCodecType() const = 0;
+
+    virtual std::vector<DeviceDisplayInfo> get_device_display_info() const = 0;
 protected:
     FrameCapture() = default;
     FrameCapture(const FrameCapture&) = delete;
diff --git a/include/spice-streaming-agent/x11-display-info.hpp 
b/include/spice-streaming-agent/x11-display-info.hpp
new file mode 100644
index 0000000..fa6afa7
--- /dev/null
+++ b/include/spice-streaming-agent/x11-display-info.hpp
@@ -0,0 +1,57 @@
+/* \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#ifndef SPICE_STREAMING_AGENT_X_DISPLAY_INFO_HPP
+#define SPICE_STREAMING_AGENT_X_DISPLAY_INFO_HPP
+
+#include <spice-streaming-agent/frame-capture.hpp>
+
+#include <X11/Xlib.h>
+
+
+namespace spice __attribute__ ((visibility ("default"))) {
+namespace streaming_agent {
+
+/**
+ * Looks up device display info by listing the xrandr outputs of @display and
+ * comparing them to card output names found under the DRM subsystem in
+ * /sys/class/drm.
+ *
+ * Throws an Error in case of error or when the DRM outputs cannot be found.
+ *
+ * @param display the X display to find the info for
+ * @return a vector of DeviceDisplayInfo structs containing the information of
+ * all the outputs used by the display
+ */
+std::vector<DeviceDisplayInfo> get_device_display_info_drm(Display *display);
+
+/**
+ * Attempts to get the device display info without using DRM. It looks up the
+ * first card in /sys/class/drm that doesn't have its outputs listed (assuming
+ * that if the card in use has DRM outputs, it would be found using the
+ * get_display_info function) and simply uses the xrandr output index as the
+ * device_display_id. This can obviously incorrectly match the device address
+ * and the device_display_ids of two unrelated devices.
+ *
+ * Unfortunately, without DRM, there is no way to match xrandr objects with the
+ * real device.
+ *
+ * @param display the X display to find the info for
+ * @return a vector of DeviceDisplayInfo structs containing the information of
+ * all the outputs used by the display
+ */
+std::vector<DeviceDisplayInfo> get_device_display_info_no_drm(Display 
*display);
+
+/**
+ * Lists xrandr outputs and returns their names in a vector of strings.
+ *
+ * @param display the X display
+ * @param window the X root window
+ * @return A vector of xrandr output names
+ */
+std::vector<std::string> get_xrandr_outputs(Display *display, Window window);
+
+}} // namespace spice::streaming_agent
+
+#endif // SPICE_STREAMING_AGENT_X_DISPLAY_INFO_HPP
diff --git a/src/Makefile.am b/src/Makefile.am
index bae3f9d..0133bf5 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -16,9 +16,11 @@ AM_CPPFLAGS = \
        -DSPICE_STREAMING_AGENT_PROGRAM \
        -I$(top_srcdir)/include \
        -DPLUGINSDIR=\"$(pkglibdir)/plugins\" \
+       $(DRM_CFLAGS) \
        $(SPICE_PROTOCOL_CFLAGS) \
        $(X11_CFLAGS) \
        $(XFIXES_CFLAGS) \
+       $(XRANDR_CFLAGS) \
        $(NULL)
 
 AM_CFLAGS = \
@@ -50,8 +52,10 @@ spice_streaming_agent_LDADD = \
        -ldl \
        -lpthread \
        libstreaming-utils.a \
+       $(DRM_LIBS) \
        $(X11_LIBS) \
        $(XFIXES_LIBS) \
+       $(XRANDR_LIBS) \
        $(JPEG_LIBS) \
        $(NULL)
 
@@ -61,6 +65,7 @@ spice_streaming_agent_SOURCES = \
        concrete-agent.hpp \
        cursor-updater.cpp \
        cursor-updater.hpp \
+       display-info.cpp \
        frame-log.cpp \
        frame-log.hpp \
        mjpeg-fallback.cpp \
@@ -69,7 +74,9 @@ spice_streaming_agent_SOURCES = \
        jpeg.hpp \
        stream-port.cpp \
        stream-port.hpp \
+       utils.cpp \
        utils.hpp \
+       x11-display-info.cpp \
        $(NULL)
 
 if HAVE_GST
diff --git a/src/display-info.cpp b/src/display-info.cpp
new file mode 100644
index 0000000..4fd1977
--- /dev/null
+++ b/src/display-info.cpp
@@ -0,0 +1,101 @@
+/* \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#include <spice-streaming-agent/display-info.hpp>
+
+#include "utils.hpp"
+#include <spice-streaming-agent/error.hpp>
+
+#include <algorithm>
+#include <cstdlib>
+#include <cstring>
+#include <fstream>
+#include <limits.h>
+
+
+namespace spice {
+namespace streaming_agent {
+
+namespace {
+
+std::string get_card_real_path(const std::string &card_path)
+{
+    char real_path_buf[PATH_MAX];
+    if (realpath(card_path.c_str(), real_path_buf) == NULL) {
+        throw Error("Failed to realpath \"" + card_path + "\": " + 
strerror(errno));
+    }
+
+    return real_path_buf;
+}
+
+} // namespace
+
+std::vector<std::string> list_cards()
+{
+    std::string glob_path = "/sys/class/drm/card*";
+    auto globs = utils::glob(glob_path);
+
+    globs.erase(std::remove_if(globs.begin(), globs.end(), [](const 
std::string &glob) {
+            // if the path contains "-", it is an output, not a card, filter 
it out
+            return glob.find("-") != glob.npos;
+        }),
+        globs.end()
+    );
+
+    return globs;
+}
+
+uint32_t read_hex_number_from_file(const std::string &path)
+{
+    uint32_t res;
+    std::ifstream vf(path);
+
+    if (vf.fail()) {
+        throw Error("Failed to open " + path + ": " + std::strerror(errno));
+    }
+
+    if (!(vf >> std::hex >> res)) {
+        throw Error("Failed to read from " + path + ": " + 
std::strerror(errno));
+    }
+
+    return res;
+}
+
+std::string get_device_address(const std::string &card_path)
+{
+    std::string real_path = get_card_real_path(card_path);
+
+    // real_path is e.g. /sys/devices/pci0000:00/0000:00:02.0/drm/card0
+    std::string device_address = "pci/";
+
+    const std::string path_prefix = "/sys/devices/pci";
+
+    // if real_path doesn't start with path_prefix
+    if (real_path.compare(0, path_prefix.length(), path_prefix)) {
+        throw Error("Invalid device path \"" + real_path + "\"");
+    }
+
+    // /sys/devices/pci0000:00/0000:00:02.0/drm/card0
+    //                 ^ ptr
+    const char *ptr = real_path.c_str() + path_prefix.length();
+
+    // copy the domain
+    device_address += std::string(ptr, 4);
+
+    // /sys/devices/pci0000:00/0000:00:02.0/drm/card0
+    //                        ^ ptr
+    ptr += 7;
+
+    uint32_t domain, bus, slot, function, n;
+    while (sscanf(ptr, "/%x:%x:%x.%x%n", &domain, &bus, &slot, &function, &n) 
== 4) {
+        char pci_node[6];
+        snprintf(pci_node, 6, "/%02x.%01x", slot, function);
+        device_address += pci_node;
+        ptr += n;
+    }
+
+    return device_address;
+}
+
+}} // namespace spice::streaming_agent
diff --git a/src/gst-plugin.cpp b/src/gst-plugin.cpp
index 097ef9d..3edf9f5 100644
--- a/src/gst-plugin.cpp
+++ b/src/gst-plugin.cpp
@@ -23,6 +23,8 @@
 
 #include <spice-streaming-agent/plugin.hpp>
 #include <spice-streaming-agent/frame-capture.hpp>
+#include <spice-streaming-agent/x11-display-info.hpp>
+
 
 #define gst_syslog(priority, str, ...) syslog(priority, "Gstreamer plugin: " 
str, ## __VA_ARGS__);
 
@@ -76,6 +78,7 @@ public:
     SpiceVideoCodecType VideoCodecType() const override {
         return settings.codec;
     }
+    std::vector<DeviceDisplayInfo> get_device_display_info() const override;
 private:
     void free_sample();
     GstElement *get_encoder_plugin(const GstreamerEncoderSettings &settings, 
GstCapsUPtr &sink_caps);
@@ -402,6 +405,17 @@ FrameInfo GstreamerFrameCapture::CaptureFrame()
     return info;
 }
 
+std::vector<DeviceDisplayInfo> 
GstreamerFrameCapture::get_device_display_info() const
+{
+    try {
+        return get_device_display_info_drm(dpy);
+    } catch (const std::exception &e) {
+        syslog(LOG_WARNING, "Failed to get device info using DRM: %s. Using 
no-DRM fallback.",
+               e.what());
+        return get_device_display_info_no_drm(dpy);
+    }
+}
+
 FrameCapture *GstreamerPlugin::CreateCapture()
 {
     return new GstreamerFrameCapture(settings);
diff --git a/src/mjpeg-fallback.cpp b/src/mjpeg-fallback.cpp
index 8081007..09f3769 100644
--- a/src/mjpeg-fallback.cpp
+++ b/src/mjpeg-fallback.cpp
@@ -7,6 +7,9 @@
 #include <config.h>
 #include "mjpeg-fallback.hpp"
 
+#include "jpeg.hpp"
+#include <spice-streaming-agent/x11-display-info.hpp>
+
 #include <cstring>
 #include <exception>
 #include <stdexcept>
@@ -15,8 +18,6 @@
 #include <syslog.h>
 #include <X11/Xlib.h>
 
-#include "jpeg.hpp"
-
 using namespace spice::streaming_agent;
 
 static inline uint64_t get_time()
@@ -40,6 +41,7 @@ public:
     SpiceVideoCodecType VideoCodecType() const override {
         return SPICE_VIDEO_CODEC_TYPE_MJPEG;
     }
+    std::vector<DeviceDisplayInfo> get_device_display_info() const override;
 private:
     MjpegSettings settings;
     Display *dpy;
@@ -137,6 +139,17 @@ FrameInfo MjpegFrameCapture::CaptureFrame()
     return info;
 }
 
+std::vector<DeviceDisplayInfo> MjpegFrameCapture::get_device_display_info() 
const
+{
+    try {
+        return get_device_display_info_drm(dpy);
+    } catch (const std::exception &e) {
+        syslog(LOG_WARNING, "Failed to get device info using DRM: %s. Using 
no-DRM fallback.",
+               e.what());
+        return get_device_display_info_no_drm(dpy);
+    }
+}
+
 FrameCapture *MjpegPlugin::CreateCapture()
 {
     return new MjpegFrameCapture(settings);
diff --git a/src/spice-streaming-agent.cpp b/src/spice-streaming-agent.cpp
index 1eb8e1b..cd23111 100644
--- a/src/spice-streaming-agent.cpp
+++ b/src/spice-streaming-agent.cpp
@@ -217,6 +217,19 @@ do_capture(StreamPort &stream_port, FrameLog &frame_log)
             throw std::runtime_error("cannot find a suitable capture system");
         }
 
+        try {
+            std::vector<DeviceDisplayInfo> display_info = 
capture->get_device_display_info();
+            syslog(LOG_DEBUG, "Got device info of %lu devices from the 
plugin", display_info.size());
+            for (const auto &info : display_info) {
+                syslog(LOG_DEBUG, "   id %u: device address %s, device display 
id: %u",
+                       info.stream_id,
+                       info.device_address.c_str(),
+                       info.device_display_id);
+            }
+        } catch (const Error &e) {
+            syslog(LOG_ERR, "Error while getting device info: %s", e.what());
+        }
+
         while (!quit_requested && streaming_requested) {
             if (++frame_count % 100 == 0) {
                 syslog(LOG_DEBUG, "SENT %d frames", frame_count);
diff --git a/src/unittests/Makefile.am b/src/unittests/Makefile.am
index 1ae5a07..8ce1f7a 100644
--- a/src/unittests/Makefile.am
+++ b/src/unittests/Makefile.am
@@ -5,6 +5,7 @@ AM_CPPFLAGS = \
        -I$(top_srcdir)/include \
        -I$(top_srcdir)/src \
        -I$(top_srcdir)/src/unittests \
+       $(DRM_CFLAGS) \
        $(SPICE_PROTOCOL_CFLAGS) \
        $(NULL)
 
@@ -43,13 +44,18 @@ hexdump_LDADD = \
 
 test_mjpeg_fallback_SOURCES = \
        test-mjpeg-fallback.cpp \
+       ../display-info.cpp \
        ../jpeg.cpp \
        ../mjpeg-fallback.cpp \
+       ../utils.cpp \
+       ../x11-display-info.cpp \
        $(NULL)
 
 test_mjpeg_fallback_LDADD = \
+       $(DRM_LIBS) \
        $(X11_LIBS) \
        $(JPEG_LIBS) \
+       $(XRANDR_LIBS) \
        $(NULL)
 
 test_stream_port_SOURCES = \
diff --git a/src/utils.cpp b/src/utils.cpp
new file mode 100644
index 0000000..b78c893
--- /dev/null
+++ b/src/utils.cpp
@@ -0,0 +1,46 @@
+/* \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#include "utils.hpp"
+
+#include <spice-streaming-agent/error.hpp>
+
+#include <glob.h>
+#include <string.h>
+#include <stdexcept>
+
+
+namespace spice {
+namespace streaming_agent {
+namespace utils {
+
+std::vector<std::string> glob(const std::string& pattern)
+{
+    glob_t glob_result{};
+
+    std::vector<std::string> filenames;
+
+    int ret = glob(pattern.c_str(), GLOB_ERR, NULL, &glob_result);
+
+    if(ret != 0) {
+        globfree(&glob_result);
+
+        if (ret == GLOB_NOMATCH) {
+            return filenames;
+        }
+
+        throw Error("glob(" + pattern + ") failed with return value " + 
std::to_string(ret) +
+                    ": " + strerror(errno));
+    }
+
+    for(size_t i = 0; i < glob_result.gl_pathc; ++i) {
+        filenames.push_back(glob_result.gl_pathv[i]);
+    }
+
+    globfree(&glob_result);
+
+    return filenames;
+}
+
+}}} // namespace spice::streaming_agent::utils
diff --git a/src/utils.hpp b/src/utils.hpp
index 64cb538..8c3b04e 100644
--- a/src/utils.hpp
+++ b/src/utils.hpp
@@ -5,6 +5,8 @@
 #ifndef SPICE_STREAMING_AGENT_UTILS_HPP
 #define SPICE_STREAMING_AGENT_UTILS_HPP
 
+#include <vector>
+#include <string>
 #include <syslog.h>
 
 
@@ -12,6 +14,8 @@ namespace spice {
 namespace streaming_agent {
 namespace utils {
 
+std::vector<std::string> glob(const std::string& pattern);
+
 template<class T>
 const T &syslog(const T &error) noexcept
 {
diff --git a/src/x11-display-info.cpp b/src/x11-display-info.cpp
new file mode 100644
index 0000000..4a03413
--- /dev/null
+++ b/src/x11-display-info.cpp
@@ -0,0 +1,302 @@
+/* \copyright
+ * Copyright 2018 Red Hat Inc. All rights reserved.
+ */
+
+#include <spice-streaming-agent/x11-display-info.hpp>
+
+#include <spice-streaming-agent/display-info.hpp>
+#include "utils.hpp"
+#include <spice-streaming-agent/error.hpp>
+
+#include <algorithm>
+#include <cstring>
+#include <map>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <X11/extensions/Xrandr.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
+
+
+namespace spice {
+namespace streaming_agent {
+
+namespace {
+
+constexpr uint32_t pci_vendor_id_redhat = 0x1b36;
+constexpr uint32_t pci_device_id_qxl = 0x0100;
+
+struct OutputInfo {
+    std::string output_name;
+    std::string card_path;
+    uint32_t card_vendor_id;
+    uint32_t card_device_id;
+    uint32_t device_display_id;
+};
+
+static const std::map<uint32_t, std::string> modesetting_output_names = {
+    {DRM_MODE_CONNECTOR_Unknown, "None"},
+    {DRM_MODE_CONNECTOR_VGA, "VGA"},
+    {DRM_MODE_CONNECTOR_DVII, "DVI-I"},
+    {DRM_MODE_CONNECTOR_DVID, "DVI-D"},
+    {DRM_MODE_CONNECTOR_DVIA, "DVI-A"},
+    {DRM_MODE_CONNECTOR_Composite, "Composite"},
+    {DRM_MODE_CONNECTOR_SVIDEO, "SVIDEO"},
+    {DRM_MODE_CONNECTOR_LVDS, "LVDS"},
+    {DRM_MODE_CONNECTOR_Component, "Component"},
+    {DRM_MODE_CONNECTOR_9PinDIN, "DIN"},
+    {DRM_MODE_CONNECTOR_DisplayPort, "DP"},
+    {DRM_MODE_CONNECTOR_HDMIA, "HDMI"},
+    {DRM_MODE_CONNECTOR_HDMIB, "HDMI-B"},
+    {DRM_MODE_CONNECTOR_TV, "TV"},
+    {DRM_MODE_CONNECTOR_eDP, "eDP"},
+    {DRM_MODE_CONNECTOR_VIRTUAL, "Virtual"},
+    {DRM_MODE_CONNECTOR_DSI, "DSI"},
+    {DRM_MODE_CONNECTOR_DPI, "DPI"},
+};
+
+// Connector type names from qxl driver
+static const std::map<uint32_t, std::string> qxl_output_names = {
+    {DRM_MODE_CONNECTOR_Unknown, "None"},
+    {DRM_MODE_CONNECTOR_VGA, "VGA"},
+    {DRM_MODE_CONNECTOR_DVII, "DVI"},
+    {DRM_MODE_CONNECTOR_DVID, "DVI"},
+    {DRM_MODE_CONNECTOR_DVIA, "DVI"},
+    {DRM_MODE_CONNECTOR_Composite, "Composite"},
+    {DRM_MODE_CONNECTOR_SVIDEO, "S-video"},
+    {DRM_MODE_CONNECTOR_LVDS, "LVDS"},
+    {DRM_MODE_CONNECTOR_Component, "CTV"},
+    {DRM_MODE_CONNECTOR_9PinDIN, "DIN"},
+    {DRM_MODE_CONNECTOR_DisplayPort, "DisplayPort"},
+    {DRM_MODE_CONNECTOR_HDMIA, "HDMI"},
+    {DRM_MODE_CONNECTOR_HDMIB, "HDMI"},
+    {DRM_MODE_CONNECTOR_TV, "TV"},
+    {DRM_MODE_CONNECTOR_eDP, "eDP"},
+    {DRM_MODE_CONNECTOR_VIRTUAL, "Virtual"},
+};
+
+std::string get_drm_name(const std::map<uint32_t, std::string> &name_map,
+                         uint32_t connector_type,
+                         uint32_t connector_type_id)
+{
+    auto name_it = name_map.find(connector_type);
+    if (name_it == name_map.end()) {
+        throw Error("Could not find DRM connector name for type " + 
std::to_string(connector_type));
+    }
+
+    return name_it->second + "-" + std::to_string(connector_type_id);
+}
+
+class DrmOutputGetter
+{
+public:
+    DrmOutputGetter(const char* card_path)
+    {
+        drm_fd = open(card_path, O_RDWR);
+        if (drm_fd < 0) {
+            throw Error(std::string("Unable to open file %s: ") + 
strerror(errno));
+        }
+
+        drm_resources = drmModeGetResources(drm_fd);
+
+        if (drm_resources == nullptr) {
+            close(drm_fd);
+            throw Error(std::string("Unable to get DRM resources for card ") + 
card_path);
+        }
+    }
+
+    ~DrmOutputGetter()
+    {
+        drmModeFreeResources(drm_resources);
+        close(drm_fd);
+    }
+
+    std::vector<std::string> get_output_names(const std::map<uint32_t, 
std::string> &names_map,
+                                              bool decrement = false)
+    {
+        std::vector<std::string> result;
+
+        for (size_t i = 0; i < drm_resources->count_connectors; ++i) {
+            drmModeConnectorPtr conn = drmModeGetConnector(drm_fd, 
drm_resources->connectors[i]);
+
+            if (conn == nullptr) {
+                throw Error(std::string("Unable to get DRM connector: ") + 
strerror(errno));
+            }
+
+            uint32_t cti = conn->connector_type_id;
+            if (decrement) {
+                cti--;
+            }
+            result.push_back(get_drm_name(names_map, conn->connector_type, 
cti));
+        }
+
+        return result;
+    }
+
+private:
+    int drm_fd = -1;
+    drmModeResPtr drm_resources = nullptr;
+};
+
+std::vector<OutputInfo> get_outputs()
+{
+    std::vector<OutputInfo> result;
+
+    for (uint8_t card_id = 0; card_id < 10; ++card_id) {
+        std::string card_name = "card" + std::to_string(card_id);
+
+        char drm_path[64];
+        snprintf(drm_path, sizeof(drm_path), DRM_DEV_NAME, DRM_DIR_NAME, 
card_id);
+
+        struct stat stat_buf;
+        if (stat(drm_path, &stat_buf) != 0) {
+            if (errno == ENOENT) {
+                // we're done searching
+                break;
+            }
+            throw Error(std::string("Error accessing DRM node for card ") + 
drm_path);
+        }
+
+        std::string sys_path = "/sys/class/drm/" + card_name;
+
+        uint32_t vendor_id = read_hex_number_from_file(sys_path + 
"/device/vendor");
+        uint32_t device_id = read_hex_number_from_file(sys_path + 
"/device/device");
+
+        std::vector<std::string> outputs;
+
+        if (vendor_id == pci_vendor_id_redhat && device_id == 
pci_device_id_qxl) {
+            // to find out whether QXL output names need decrementing, look for
+            // an output called Virtual-0 in /sys/class/drm and if we find one,
+            // decrement the number in the output names
+            const auto globs = utils::glob("/sys/class/drm/card*-Virtual-0");
+            outputs = 
DrmOutputGetter(drm_path).get_output_names(qxl_output_names, globs.size() > 0);
+        } else {
+            outputs = 
DrmOutputGetter(drm_path).get_output_names(modesetting_output_names);
+        }
+
+        for (uint32_t i = 0; i < outputs.size(); ++i) {
+            result.push_back({outputs[i],
+                              sys_path,
+                              vendor_id,
+                              device_id,
+                              i});
+        }
+    }
+
+    return result;
+}
+
+} // namespace
+
+std::vector<std::string> get_xrandr_outputs(Display *display, Window window)
+{
+    XRRScreenResources *screen_resources = XRRGetScreenResources(display, 
window);
+    std::vector<std::string> result;
+    for (int i = 0; i < screen_resources->noutput; ++i) {
+        XRROutputInfo *output_info = XRRGetOutputInfo(display,
+                                                      screen_resources,
+                                                      
screen_resources->outputs[i]);
+
+        result.emplace_back(output_info->name);
+
+        XRRFreeOutputInfo(output_info);
+    }
+
+    XRRFreeScreenResources(screen_resources);
+    return result;
+}
+
+std::vector<DeviceDisplayInfo> get_device_display_info_drm(Display *display)
+{
+    auto outputs = get_outputs();
+
+    // sorting by output name, may not be necessary (the list should be sorted 
out of glob)
+    std::sort(outputs.begin(), outputs.end(), [](const OutputInfo &oi1, const 
OutputInfo &oi2) {
+            return oi1.output_name > oi2.output_name;
+        }
+    );
+
+    // Check if the output names of QXL cards start at Virtual-1 and if so,
+    // subtract one from each of them
+    for (auto &output : outputs) {
+        // if we find a QXL card
+        if (output.card_vendor_id == pci_vendor_id_redhat &&
+            output.card_device_id == pci_device_id_qxl)
+        {
+            // if the first name is Virtual-0, we know we are good, quit the 
loop
+            if (output.output_name == "Virtual-0") {
+                break;
+            }
+
+            // if the name starts with "Virtual-"
+            if (output.output_name.compare(0, 8, "Virtual-") == 0) {
+                // decrement the last digit by one
+                // fails if the number at the end is more than one digit,
+                // which would imply multiple QXL devices, an unsupported case
+                output.output_name[output.output_name.length() - 1]--;
+            }
+        }
+    }
+
+    std::map<std::string, OutputInfo> output_map;
+    for (const auto &output : outputs) {
+        output_map[output.output_name] = output;
+    }
+
+    auto xrandr_outputs = get_xrandr_outputs(display, RootWindow(display, 
XDefaultScreen(display)));
+
+    std::vector<DeviceDisplayInfo> result;
+
+    for (uint32_t i = 0; i < xrandr_outputs.size(); ++i) {
+        const auto &xoutput = xrandr_outputs[i];
+        const auto it = output_map.find(xoutput);
+        if (it == output_map.end()) {
+            throw Error("Could not find card for output " + xoutput);
+        }
+
+        std::string device_address = get_device_address(it->second.card_path);
+
+        result.push_back({i, device_address, it->second.device_display_id});
+    }
+
+    return result;
+}
+
+std::vector<DeviceDisplayInfo> get_device_display_info_no_drm(Display *display)
+{
+    // look for the first card that doesn't list its outputs (and therefore
+    // doesn't support DRM), that's the best we can do...
+    const auto globs = utils::glob("/sys/class/drm/card*");
+
+    std::string found_card_path;
+    for (const auto &path : globs) {
+        std::string card_output = path.substr(path.rfind("/") + 1, path.npos);
+        auto dash_it = card_output.find("-");
+        // if this file is a card (and not an output)
+        if (dash_it == card_output.npos) {
+            // if we already have a found card, this means it doesn't have any 
outputs,
+            // we have found our card
+            if (!found_card_path.empty()) {
+                break;
+            }
+            found_card_path = card_output;
+        } else {
+            found_card_path = "";
+        }
+    }
+
+    std::string device_address = get_device_address(found_card_path);
+
+    auto xrandr_outputs = get_xrandr_outputs(display, RootWindow(display, 
XDefaultScreen(display)));
+
+    std::vector<DeviceDisplayInfo> result;
+
+    for (uint32_t i = 0; i < xrandr_outputs.size(); ++i) {
+        result.push_back({i, device_address, i});
+    }
+
+    return result;
+}
+
+}} // namespace spice::streaming_agent
-- 
2.20.1

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