Add nvinfo package to query system state

This change adds an nvinfo package with HasNVML and IsTegraSystem
functions. These functions can be used to control behaviour on
different platforms.

Signed-off-by: Evan Lezar <elezar@nvidia.com>

pkg/nvinfo/info.go

@@ -0,0 +1,65 @@
+/**
+# Copyright (c) 2022, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+**/
+
+package nvinfo
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"github.com/NVIDIA/go-nvml/pkg/dl"
+)
+
+// HasNVML returns true if NVML is detected on the system
+func HasNVML() (bool, string) {
+	const (
+		nvmlLibraryName      = "libnvidia-ml.so.1"
+		nvmlLibraryLoadFlags = dl.RTLD_LAZY
+	)
+	lib := dl.New(nvmlLibraryName, nvmlLibraryLoadFlags)
+	if err := lib.Open(); err != nil {
+		return false, fmt.Sprintf("could not load NVML: %v", err)
+	}
+	defer lib.Close()
+
+	return true, "found NVML library"
+}
+
+// IsTegraSystem returns true if the system is detected as a Tegra-based system
+func IsTegraSystem() (bool, string) {
+	const tegraReleaseFile = "/etc/nv_tegra_release"
+	const tegraFamilyFile = "/sys/devices/soc0/family"
+
+	if info, err := os.Stat(tegraReleaseFile); err == nil && !info.IsDir() {
+		return true, fmt.Sprintf("%v found", tegraReleaseFile)
+	}
+
+	if info, err := os.Stat(tegraFamilyFile); err != nil || info.IsDir() {
+		return false, fmt.Sprintf("%v file not found", tegraFamilyFile)
+	}
+
+	contents, err := os.ReadFile(tegraFamilyFile)
+	if err != nil {
+		return false, fmt.Sprintf("could not read %v", tegraFamilyFile)
+	}
+
+	if strings.HasPrefix(strings.ToLower(string(contents)), "tegra") {
+		return true, fmt.Sprintf("%v has 'tegra' prefix", tegraFamilyFile)
+	}
+
+	return false, fmt.Sprintf("%v has no 'tegra' prefix", tegraFamilyFile)
+}