Minidump: Add support for reading/writing strings

Summary:
Strings in minidump files are stored as a 32-bit length field, giving
the length of the string in *bytes*, which is followed by the
appropriate number of UTF16 code units. The string is also supposed to
be null-terminated, and the null-terminator is not a part of the length
field. This patch:
- adds support for reading these strings out of the minidump file (this
  implementation does not depend on proper null-termination)
- adds support for writing them to a minidump file
- using the previous two pieces implements proper (de)serialization of
  the CSDVersion field of the SystemInfo stream. Previously, this was
  only read/written as hex, and no attempt was made to access the
  referenced string -- now this string is read and written correctly.

The changes are tested via yaml2obj|obj2yaml round-trip as well as a
unit test which checks the corner cases of the string deserialization
logic.

Reviewers: jhenderson, zturner, clayborg

Subscribers: llvm-commits, aprantl, markmentovai, amccarth, lldb-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59775

llvm-svn: 357749

2 files changed, 35 insertions, 2 deletions

diff --git a/llvm/unittests/Object/MinidumpTest.cpp b/llvm/unittests/Object/MinidumpTest.cpp
index 97fde12c0f8..06034e1e5ad 100644
--- a/llvm/unittests/Object/MinidumpTest.cpp
+++ b/llvm/unittests/Object/MinidumpTest.cpp
@@ -249,3 +249,38 @@ TEST(MinidumpFile, getSystemInfo) {
   EXPECT_EQ(0x08070605u, Info.CPU.X86.FeatureInfo);
   EXPECT_EQ(0x02010009u, Info.CPU.X86.AMDExtendedFeatures);
 }
+
+TEST(MinidumpFile, getString) {
+  std::vector<uint8_t> ManyStrings{
+      // Header
+      'M', 'D', 'M', 'P', 0x93, 0xa7, 0, 0, // Signature, Version
+      2, 0, 0, 0,                           // NumberOfStreams,
+      0x20, 0, 0, 0,                        // StreamDirectoryRVA
+      0, 1, 2, 3, 4, 5, 6, 7,               // Checksum, TimeDateStamp
+      8, 9, 0, 1, 2, 3, 4, 5,               // Flags
+                                            // Stream Directory
+      0, 0, 0, 0, 0, 0, 0, 0,               // Type, DataSize,
+      0x20, 0, 0, 0,                        // RVA
+      1, 0, 0, 0, 0, 0,                     // String1 - odd length
+      0, 0, 1, 0, 0, 0,                     // String2 - too long
+      2, 0, 0, 0, 0, 0xd8,                  // String3 - invalid utf16
+      0, 0, 0, 0, 0, 0,                     // String4 - ""
+      2, 0, 0, 0, 'a', 0,                   // String5 - "a"
+      0,                                    // Mis-align next string
+      2, 0, 0, 0, 'a', 0,                   // String6 - "a"
+
+  };
+  auto ExpectedFile = create(ManyStrings);
+  ASSERT_THAT_EXPECTED(ExpectedFile, Succeeded());
+  const MinidumpFile &File = **ExpectedFile;
+  EXPECT_THAT_EXPECTED(File.getString(44), Failed<BinaryError>());
+  EXPECT_THAT_EXPECTED(File.getString(50), Failed<BinaryError>());
+  EXPECT_THAT_EXPECTED(File.getString(56), Failed<BinaryError>());
+  EXPECT_THAT_EXPECTED(File.getString(62), HasValue(""));
+  EXPECT_THAT_EXPECTED(File.getString(68), HasValue("a"));
+  EXPECT_THAT_EXPECTED(File.getString(75), HasValue("a"));
+
+  // Check the case when the size field does not fit into the remaining data.
+  EXPECT_THAT_EXPECTED(File.getString(ManyStrings.size() - 2),
+                       Failed<BinaryError>());
+}
diff --git a/llvm/unittests/ObjectYAML/MinidumpYAMLTest.cpp b/llvm/unittests/ObjectYAML/MinidumpYAMLTest.cpp
index d172ccf9301..66d44e06759 100644
--- a/llvm/unittests/ObjectYAML/MinidumpYAMLTest.cpp
+++ b/llvm/unittests/ObjectYAML/MinidumpYAMLTest.cpp
@@ -33,7 +33,6 @@ Streams:
   - Type:            SystemInfo
     Processor Arch:  ARM64
     Platform ID:     Linux
-    CSD Version RVA: 0x01020304
     CPU:
       CPUID:           0x05060708
   - Type:            LinuxMaps
@@ -54,7 +53,6 @@ Streams:
   const SystemInfo &SysInfo = *ExpectedSysInfo;
   EXPECT_EQ(ProcessorArchitecture::ARM64, SysInfo.ProcessorArch);
   EXPECT_EQ(OSPlatform::Linux, SysInfo.PlatformId);
-  EXPECT_EQ(0x01020304u, SysInfo.CSDVersionRVA);
   EXPECT_EQ(0x05060708u, SysInfo.CPU.Arm.CPUID);
 
   EXPECT_EQ(StreamType::LinuxMaps, File.streams()[1].Type);