[PATCH] D63177: [lld] Allow unrecognized signatures in debug sections

[Vladimir Panteleev via Phabricator via llvm-commits]

CyberShadow created this revision.
CyberShadow added reviewers: rnk, ruiu.
Herald added subscribers: llvm-commits, aprantl.
Herald added a project: LLVM.

An unrecognized signature (magic) at the beginning of a debug section
should not be a fatal error; it only means that the debug information
is in a format that is not supported by LLD. This can be due to it
being in CodeView versions 3 or earlier. These can occur in old import
libraries from legacy SDKs.

The test case was verified to work with MS link.exe.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D63177

Files:
  lld/COFF/Chunks.cpp
  lld/test/COFF/allow-unknown-debug-info.test


Index: lld/test/COFF/allow-unknown-debug-info.test
===================================================================
--- /dev/null
+++ lld/test/COFF/allow-unknown-debug-info.test
@@ -0,0 +1,26 @@
+# RUN: yaml2obj %s > %t.obj
+# RUN: lld-link /dll /noentry /debug %t.obj 2>&1 | FileCheck %s
+
+# CHECK: ignoring section .debug$S with unrecognized magic 0x1
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_I386
+  Characteristics: []
+sections:
+  - Name:            '.debug$S'
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_DISCARDABLE, IMAGE_SCN_MEM_READ ]
+    SectionData:     01000000
+symbols:
+  - Name:            '.debug$S'
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          4
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          0
Index: lld/COFF/Chunks.cpp
===================================================================
--- lld/COFF/Chunks.cpp
+++ lld/COFF/Chunks.cpp
@@ -601,12 +601,15 @@
   if (!SectionName.startswith(".debug$"))
     fatal("invalid section: " + SectionName);
 
-  unsigned Magic = support::endian::read32le(Data.data());
-  unsigned ExpectedMagic = SectionName == ".debug$H"
+  uint32_t Magic = support::endian::read32le(Data.data());
+  uint32_t ExpectedMagic = SectionName == ".debug$H"
                                ? DEBUG_HASHES_SECTION_MAGIC
                                : DEBUG_SECTION_MAGIC;
-  if (Magic != ExpectedMagic)
-    fatal("section: " + SectionName + " has an invalid magic: " + Twine(Magic));
+  if (Magic != ExpectedMagic) {
+    warn("ignoring section " + SectionName + " with unrecognized magic 0x" +
+         utohexstr(Magic));
+    return {};
+  }
   return Data.slice(4);
 }
 


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