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#include <xf86drm.h>
#include <array>
#include <map>
#include <mutex>
#include <optional>
#include <sys/stat.h>
#include "Drm.hpp"
namespace {
using SDRMNodePair = std::array<dev_t, 2>;
std::optional<SDRMNodePair> getDrmNodePair(int fd1, int fd2) {
const auto DEVA = DRM::devIDFromFD(fd1);
const auto DEVB = DRM::devIDFromFD(fd2);
if (!DEVA || !DEVB)
return std::nullopt;
SDRMNodePair pair = {*DEVA, *DEVB};
if (pair[0] > pair[1])
std::swap(pair[0], pair[1]);
return pair;
}
}
std::optional<dev_t> DRM::devIDFromFD(int fd) {
struct stat stat = {};
if (fstat(fd, &stat) != 0 || !S_ISCHR(stat.st_mode))
return std::nullopt;
return stat.st_rdev;
}
bool DRM::sameGpu(int fd1, int fd2) {
if (fd1 < 0 || fd2 < 0 || fd1 == fd2)
return true;
static std::mutex cacheMutex;
static std::map<SDRMNodePair, bool> sameGpuCache;
const auto NODEPAIR = getDrmNodePair(fd1, fd2);
if (NODEPAIR) {
std::scoped_lock lock(cacheMutex);
if (const auto it = sameGpuCache.find(*NODEPAIR); it != sameGpuCache.end())
return it->second;
}
drmDevice* devA = nullptr;
drmDevice* devB = nullptr;
if (drmGetDevice2(fd1, 0, &devA) != 0)
return false;
if (drmGetDevice2(fd2, 0, &devB) != 0) {
drmFreeDevice(&devA);
return false;
}
bool same = drmDevicesEqual(devA, devB);
drmFreeDevice(&devA);
drmFreeDevice(&devB);
if (NODEPAIR) {
std::scoped_lock lock(cacheMutex);
sameGpuCache[*NODEPAIR] = same;
}
return same;
}
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