check for readable host id files before read (#1400)

* check for readable host id files before read
* reset vfs between tests

src/SDK/Resource/Detectors/Host.php

@@ -52,8 +52,9 @@ final class Host implements ResourceDetectorInterface
         $paths = [self::PATH_ETC_MACHINEID, self::PATH_VAR_LIB_DBUS_MACHINEID];
 
         foreach ($paths as $path) {
-            if (file_exists($this->dir . $path)) {
-                return trim(file_get_contents($this->dir . $path));
+            $file = $this->dir . $path;
+            if (is_file($file) && is_readable($file)) {
+                return trim(file_get_contents($file));
             }
         }
 
@@ -62,13 +63,14 @@ final class Host implements ResourceDetectorInterface
 
     private function getBsdId(): ?string
     {
-        if (file_exists($this->dir . self::PATH_ETC_HOSTID)) {
-            return trim(file_get_contents($this->dir . self::PATH_ETC_HOSTID));
+        $file = $this->dir . self::PATH_ETC_HOSTID;
+        if (is_file($file) && is_readable($file)) {
+            return trim(file_get_contents($file));
         }
 
-        $out = exec('kenv -q smbios.system.uuid');
+        $out = exec('which kenv && kenv -q smbios.system.uuid');
 
-        if ($out !== false) {
+        if ($out) {
             return $out;
         }
 

tests/Unit/SDK/Resource/Detectors/HostTest.php

@@ -7,6 +7,7 @@ namespace OpenTelemetry\Tests\Unit\SDK\Resource\Detectors;
 use OpenTelemetry\SDK\Resource\Detectors\Host;
 use OpenTelemetry\SemConv\ResourceAttributes;
 use org\bovigo\vfs\vfsStream;
+use org\bovigo\vfs\vfsStreamDirectory;
 use PHPUnit\Framework\Attributes\CoversClass;
 use PHPUnit\Framework\Attributes\DataProvider;
 use PHPUnit\Framework\TestCase;
@@ -14,6 +15,12 @@ use PHPUnit\Framework\TestCase;
 #[CoversClass(Host::class)]
 class HostTest extends TestCase
 {
+    public function setUp(): void
+    {
+        //reset vfs between tests
+        vfsStream::setup('/');
+    }
+
     public function test_host_get_resource(): void
     {
         $resourceDetector = new Host();
@@ -72,4 +79,33 @@ class HostTest extends TestCase
             ['BSD', $etc_hostid, '1234567890'],
         ];
     }
+
+    #[DataProvider('nonReadableFileProvider')]
+    public function test_file_not_readable(string $os, vfsStreamDirectory $root): void
+    {
+        $resourceDetector = new Host($root->url(), $os);
+        $resource = $resourceDetector->getResource();
+
+        $hostId = $resource->getAttributes()->get(ResourceAttributes::HOST_ID);
+        $this->assertNull($hostId);
+    }
+
+    public static function nonReadableFileProvider(): array
+    {
+        $root = vfsStream::setup('/');
+        $etc = vfsStream::newDirectory('etc')->at($root);
+        vfsStream::newFile('machine-id')
+            ->at($etc)
+            ->setContent('you-cant-see-me')
+            ->chmod(0222);
+        vfsStream::newFile('hostid')
+            ->at($etc)
+            ->setContent('you-cant-see-me')
+            ->chmod(0222);
+
+        return [
+            ['Linux', $root],
+            ['BSD', $root],
+        ];
+    }
 }