[sdk] Support split reads in OTEL_DIAGNOSTICS.json config file parser logic (open-telemetry#5884)

Co-authored-by: Piotr Kiełkowicz <[email protected]>

Author: rajkumar-rangaraj

src/OpenTelemetry/Internal/SelfDiagnosticsConfigParser.cs

@@ -66,10 +66,21 @@ public bool TryGetConfiguration(
                 this.configBuffer = buffer;
             }
 
-            // TODO: Fix CA2022 - Avoid inexact read with 'System.IO.FileStream.Read(byte[], int, int)'
-            // Added _ = as a workaround to suppress the warning
-            _ = file.Read(buffer, 0, buffer.Length);
-            string configJson = Encoding.UTF8.GetString(buffer);
+            int bytesRead = 0;
+            int totalBytesRead = 0;
+
+            while (totalBytesRead < buffer.Length)
+            {
+                bytesRead = file.Read(buffer, totalBytesRead, buffer.Length - totalBytesRead);
+                if (bytesRead == 0)
+                {
+                    break;
+                }
+
+                totalBytesRead += bytesRead;
+            }
+
+            string configJson = Encoding.UTF8.GetString(buffer, 0, totalBytesRead);
 
             if (!TryParseLogDirectory(configJson, out logDirectory))
             {

test/OpenTelemetry.Tests/Internal/SelfDiagnosticsEventListenerTest.cs

@@ -125,8 +125,20 @@ public void SelfDiagnosticsEventListener_EmitEvent_OmitAsConfigured()
         using FileStream file = File.Open(LOGFILEPATH, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
         var buffer = new byte[256];
 
-        // Suppress CA2022 error: Avoid inexact read with 'System.IO.FileStream.Read(byte[], int, int)'
-        _ = file.Read(buffer, 0, buffer.Length);
+        int bytesRead = 0;
+        int totalBytesRead = 0;
+
+        while (totalBytesRead < buffer.Length)
+        {
+            bytesRead = file.Read(buffer, totalBytesRead, buffer.Length - totalBytesRead);
+            if (bytesRead == 0)
+            {
+                break;
+            }
+
+            totalBytesRead += bytesRead;
+        }
+
         Assert.Equal('\0', (char)buffer[0]);
     }
 
@@ -259,9 +271,21 @@ private static void AssertFileOutput(string filePath, string eventMessage)
         using FileStream file = File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
         var buffer = new byte[256];
 
-        // Suppress CA2022 error: Avoid inexact read with 'System.IO.FileStream.Read(byte[], int, int)'
-        _ = file.Read(buffer, 0, buffer.Length);
-        string logLine = Encoding.UTF8.GetString(buffer);
+        int bytesRead = 0;
+        int totalBytesRead = 0;
+
+        while (totalBytesRead < buffer.Length)
+        {
+            bytesRead = file.Read(buffer, totalBytesRead, buffer.Length - totalBytesRead);
+            if (bytesRead == 0)
+            {
+                break;
+            }
+
+            totalBytesRead += bytesRead;
+        }
+
+        string logLine = Encoding.UTF8.GetString(buffer, 0, totalBytesRead);
         string logMessage = ParseLogMessage(logLine);
         Assert.StartsWith(eventMessage, logMessage);
     }