[Object] Add basic minidump support

Summary:
This patch adds basic support for reading minidump files. It contains
the definitions of various important minidump data structures (header,
stream directory), and of one minidump stream (SystemInfo). The ability
to read other streams will be added in follow-up patches. However, all
streams can be read even now as raw data, which means lldb's minidump
support (where this code is taken from) can be immediately rebased on
top of this patch as soon as it lands.

As we don't have any support for generating minidump files (yet), this
tests the code via unit tests with some small handcrafted binaries in
the form of c char arrays.

Reviewers: Bigcheese, jhenderson, zturner

Subscribers: srhines, dschuff, mgorny, fedor.sergeev, lemo, clayborg, JDevlieghere, aprantl, lldb-commits, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59291

llvm-svn: 356652

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/BinaryFormat/Magic.cpp b/llvm/lib/BinaryFormat/Magic.cpp
index 5e9d6e73257..85f944fa6ab 100644
--- a/llvm/lib/BinaryFormat/Magic.cpp
+++ b/llvm/lib/BinaryFormat/Magic.cpp
@@ -181,7 +181,8 @@ file_magic llvm::identify_magic(StringRef Magic) {
       return file_magic::coff_object;
     break;
 
-  case 'M': // Possible MS-DOS stub on Windows PE file or MSF/PDB file.
+  case 'M': // Possible MS-DOS stub on Windows PE file, MSF/PDB file or a
+            // Minidump file.
     if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) {
       uint32_t off = read32le(Magic.data() + 0x3c);
       // PE/COFF file, either EXE or DLL.
@@ -191,6 +192,8 @@ file_magic llvm::identify_magic(StringRef Magic) {
     }
     if (Magic.startswith("Microsoft C/C++ MSF 7.00\r\n"))
       return file_magic::pdb;
+    if (startswith(Magic, "MDMP"))
+      return file_magic::minidump;
     break;
 
   case 0x64: // x86-64 or ARM64 Windows.