[YetiCommon] Scramble test binaries

Applies b -> 255-b for every byte of the test binaries of
ModuleParserTests in order to prevent binary detection.

Also works around a bug in ElfSharp where files are not always closed,
see konrad-kruczynski/elfsharp#91. This
lead to errors deleting temp files.

GitOrigin-RevId: 107cfffd226c69dde2ad2d3bdd378be2aba3ef55

YetiCommon.Tests/ModuleParserTests.ParseBuildIdInfo.cs

@@ -1,4 +1,5 @@
-using System.IO;
+using System;
+using System.IO;
 using NUnit.Framework;
 
 namespace YetiCommon.Tests
@@ -19,13 +20,16 @@ public partial class ModuleParserTests
                   "FDF485D6-E134-4825-885F-03517602265D-00000001")]
         public void ParseBuildId_Succeeds(string filename, ModuleFormat format, string buildId)
         {
-            string path = Path.Combine(TestContext.CurrentContext.TestDirectory, "TestData",
-                                       "ModuleParserTests", filename);
-            var moduleParser = new ModuleParser();
-            BuildIdInfo output = moduleParser.ParseBuildIdInfo(path, format);
+            string scrambledPath = Path.Combine(TestContext.CurrentContext.TestDirectory,
+                                                "TestData", "ModuleParserTests", filename);
+            using (TempFile tmpFile = Unscramble(scrambledPath))
+            {
+                var moduleParser = new ModuleParser();
+                BuildIdInfo output = moduleParser.ParseBuildIdInfo(tmpFile.Path, format);
 
-            Assert.IsFalse(output.HasError);
-            Assert.True(output.Data.Matches(new BuildId(buildId), format));
+                Assert.IsFalse(output.HasError);
+                Assert.True(output.Data.Matches(new BuildId(buildId), format));
+            }
         }
 
         [Test]
@@ -49,13 +53,48 @@ public void ParseBuildId_FileNotFound([Values] ModuleFormat format)
         [TestCase("hello_dotnet_dll.dat", ModuleFormat.Pdb)]
         public void ParseBuildId_IncorrectFormat(string filename, ModuleFormat format)
         {
-            string path = Path.Combine(TestContext.CurrentContext.TestDirectory, "TestData",
-                                       "ModuleParserTests", filename);
-            var moduleParser = new ModuleParser();
-            BuildIdInfo output = moduleParser.ParseBuildIdInfo(path, format);
+            string scrambledPath = Path.Combine(TestContext.CurrentContext.TestDirectory,
+                                                "TestData", "ModuleParserTests", filename);
+            using (TempFile tmpFile = Unscramble(scrambledPath))
+            {
+                var moduleParser = new ModuleParser();
+                BuildIdInfo output = moduleParser.ParseBuildIdInfo(tmpFile.Path, format);
+
+                Assert.IsTrue(output.HasError);
+                Assert.That(
+                    output.Error.Equals(ErrorStrings.InvalidSymbolFileFormat(tmpFile.Path, format)));
+            }
+        }
+
+        class TempFile : IDisposable
+        {
+            public string Path { get; } = System.IO.Path.GetTempFileName();
+
+            public void Dispose()
+            {
+                File.Delete(Path);
+            }
+        }
+
+        /// <summary>
+        /// Unscrambles test data to addresses a Google policy that does not allow us to check in
+        /// binaries.
+        /// </summary>
+        /// <param name="filename">Name of the scrambled file in TestData\ModuleParserTests</param>
+        /// <returns>Unscrambled TempFile</returns>
+        TempFile Unscramble(string filename)
+        {
+            string scrambledPath = Path.Combine(TestContext.CurrentContext.TestDirectory,
+                                                "TestData", "ModuleParserTests", filename);
+            byte[] data = File.ReadAllBytes(scrambledPath);
+            for (int i = 0; i < data.Length; i++)
+            {
+                data[i] = (byte)(255 - data[i]);
+            }
 
-            Assert.IsTrue(output.HasError);
-            Assert.That(output.Error.Equals(ErrorStrings.InvalidSymbolFileFormat(path, format)));
+            TempFile file = new TempFile();
+            File.WriteAllBytes(file.Path, data);
+            return file;
         }
     }
 }

YetiCommon.Tests/TestData/ModuleParserTests/README.md

@@ -2,4 +2,4 @@
 
 The ModuleParserTests parse different binary test files. To prevent detection
 of binaries in the code base, and accidental execution, the files have been
-named `.dat`.
+scrambled by applying b -> 255-b for every byte and named `.dat`.

YetiCommon/ModuleParser.cs

@@ -111,30 +111,34 @@ public BuildIdInfo ParseBuildIdInfo(string filepath, ModuleFormat format)
         BuildIdInfo ParseBuildIdFromElf(string filepath)
         {
             var output = new BuildIdInfo();
-            if (!ELFReader.TryLoad(filepath, out IELF elfReader))
-            {
-                output.AddError(ErrorStrings.InvalidSymbolFileFormat(filepath, ModuleFormat.Elf));
-                return output;
-            }
-
-            using (elfReader)
+            using (Stream stream = File.OpenRead(filepath))
             {
-                if (!elfReader.TryGetSection(_buildIdName, out ISection buildIdSection))
+                if (!ELFReader.TryLoad(stream, false, out IELF elfReader))
                 {
                     output.AddError(
-                        ErrorStrings.FailedToReadBuildId(filepath, ErrorStrings.EmptyBuildId));
+                        ErrorStrings.InvalidSymbolFileFormat(filepath, ModuleFormat.Elf));
                     return output;
                 }
 
-                if (buildIdSection is INoteSection buildIdNoteSection)
-                {
-                    byte[] contents = buildIdNoteSection.Description;
-                    output.Data = ParseBuildIdValue(contents);
-                }
-                else
+                using (elfReader)
                 {
-                    output.AddError(
-                        ErrorStrings.FailedToReadBuildId(filepath, ErrorStrings.EmptyBuildId));
+                    if (!elfReader.TryGetSection(_buildIdName, out ISection buildIdSection))
+                    {
+                        output.AddError(
+                            ErrorStrings.FailedToReadBuildId(filepath, ErrorStrings.EmptyBuildId));
+                        return output;
+                    }
+
+                    if (buildIdSection is INoteSection buildIdNoteSection)
+                    {
+                        byte[] contents = buildIdNoteSection.Description;
+                        output.Data = ParseBuildIdValue(contents);
+                    }
+                    else
+                    {
+                        output.AddError(
+                            ErrorStrings.FailedToReadBuildId(filepath, ErrorStrings.EmptyBuildId));
+                    }
                 }
             }
 
@@ -382,26 +386,29 @@ public bool IsValidElf(string filepath, bool isDebugInfoFile, out string errorMe
                 return false;
             }
 
-            if (!ELFReader.TryLoad(filepath, out IELF elfReader))
-            {
-                return false;
-            }
-
-            using (elfReader)
+            using (Stream stream = File.OpenRead(filepath))
             {
-                if (!isDebugInfoFile)
+                if (!ELFReader.TryLoad(stream, false, out IELF elfReader))
                 {
-                    // If we are not to check the presence of .debug_info, it is sufficient that
-                    // the file has a valid ELF format.
-                    return true;
+                    return false;
                 }
 
-                if (elfReader.TryGetSection(_debugInfoName, out ISection _))
+                using (elfReader)
                 {
-                    return true;
-                }
+                    if (!isDebugInfoFile)
+                    {
+                        // If we are not to check the presence of .debug_info, it is sufficient that
+                        // the file has a valid ELF format.
+                        return true;
+                    }
 
-                errorMessage += ErrorStrings.MissingDebugInfoInSymbolFile(filepath);
+                    if (elfReader.TryGetSection(_debugInfoName, out ISection _))
+                    {
+                        return true;
+                    }
+
+                    errorMessage += ErrorStrings.MissingDebugInfoInSymbolFile(filepath);
+                }
             }
 
             return false;