[llvm] r369169 - [llvm-readobj] Fallback to PT_NOTE if file doesn't have sections

[Petr Hosek via llvm-commits]

Author: phosek
Date: Fri Aug 16 16:15:40 2019
New Revision: 369169

URL: http://llvm.org/viewvc/llvm-project?rev=369169&view=rev
Log:
[llvm-readobj] Fallback to PT_NOTE if file doesn't have sections

This is useful when trying to read notes from stripped files and matches
the behavior of GNU readelf and eu-readelf.

Differential Revision: https://reviews.llvm.org/D66358

Modified:
    llvm/trunk/test/tools/llvm-readobj/gnu-notes.test
    llvm/trunk/tools/llvm-readobj/ELFDumper.cpp

Modified: llvm/trunk/test/tools/llvm-readobj/gnu-notes.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/tools/llvm-readobj/gnu-notes.test?rev=369169&r1=369168&r2=369169&view=diff
==============================================================================
--- llvm/trunk/test/tools/llvm-readobj/gnu-notes.test (original)
+++ llvm/trunk/test/tools/llvm-readobj/gnu-notes.test Fri Aug 16 16:15:40 2019
@@ -3,18 +3,21 @@
 # RUN: yaml2obj --docnum=1 %s > %t1.so
 # RUN: llvm-readelf --notes %t1.so | FileCheck %s --check-prefix=GNU --strict-whitespace --match-full-lines
 # RUN: llvm-readobj --notes %t1.so | FileCheck %s --check-prefix=LLVM
+# RUN: llvm-objcopy --strip-sections %t1.so %t1.stripped.so
+# RUN: llvm-readelf --notes %t1.stripped.so | FileCheck %s --check-prefix=GNU-STRIPPED --strict-whitespace --match-full-lines
+# RUN: llvm-readobj --notes %t1.stripped.so | FileCheck %s --check-prefix=LLVM-STRIPPED
 
-#      GNU:Displaying notes found at file offset 0x00000200 with length 0x00000020:
+#      GNU:Displaying notes found at file offset 0x00000238 with length 0x00000020:
 # GNU-NEXT:  Owner                Data size 	Description
 # GNU-NEXT:  GNU                  0x00000010	NT_GNU_ABI_TAG (ABI version tag)
 # GNU-NEXT:    OS: Linux, ABI: 2.6.32
 
-#      GNU:Displaying notes found at file offset 0x00000220 with length 0x00000020:
+#      GNU:Displaying notes found at file offset 0x00000258 with length 0x00000020:
 # GNU-NEXT:  Owner                Data size 	Description
 # GNU-NEXT:  GNU                  0x00000010	NT_GNU_BUILD_ID (unique build ID bitstring)
 # GNU-NEXT:    Build ID: 4fcb712aa6387724a9f465a32cd8c14b
 
-#      GNU:Displaying notes found at file offset 0x00000240 with length 0x0000001c:
+#      GNU:Displaying notes found at file offset 0x00000278 with length 0x0000001c:
 # GNU-NEXT:  Owner                Data size 	Description
 # GNU-NEXT:  GNU                  0x00000009	NT_GNU_GOLD_VERSION (gold version)
 # GNU-NEXT:    Version: gold 1.11
@@ -53,6 +56,24 @@
 # LLVM-NEXT:   }
 # LLVM-NEXT: ]
 
+# LLVM-STRIPPED:      Notes [
+# LLVM-STRIPPED-NEXT:   NoteSection {
+# LLVM-STRIPPED-NEXT:     Offset: 0x40
+# LLVM-STRIPPED-NEXT:     Size: 0x20
+# LLVM-STRIPPED-NEXT:     Note {
+# LLVM-STRIPPED-NEXT:       Owner: GNU
+# LLVM-STRIPPED-NEXT:       Data size: 0x10
+# LLVM-STRIPPED-NEXT:       Type: NT_GNU_BUILD_ID (unique build ID bitstring)
+# LLVM-STRIPPED-NEXT:       Build ID: 4fcb712aa6387724a9f465a32cd8c14b
+# LLVM-STRIPPED-NEXT:     }
+# LLVM-STRIPPED-NEXT:   }
+# LLVM-STRIPPED-NEXT: ]
+
+#      GNU-STRIPPED:Displaying notes found at file offset 0x00000040 with length 0x00000020:
+# GNU-STRIPPED-NEXT:  Owner                Data size 	Description
+# GNU-STRIPPED-NEXT:  GNU                  0x00000010	NT_GNU_BUILD_ID (unique build ID bitstring)
+# GNU-STRIPPED-NEXT:    Build ID: 4fcb712aa6387724a9f465a32cd8c14b
+
 --- !ELF
 FileHeader:
   Class:   ELFCLASS64
@@ -74,6 +95,11 @@ Sections:
     Type:         SHT_NOTE
     AddressAlign: 0x0000000000000004
     Content:      040000000900000004000000474E5500676F6C6420312E3131000000
+ProgramHeaders:
+  - Type: PT_NOTE
+    FileSize: 0x20
+    Sections:
+      - Section: .note.gnu.build-id
 
 ## Test tools report an error if a note section has an invalid offset
 ## that goes past the end of file.

Modified: llvm/trunk/tools/llvm-readobj/ELFDumper.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-readobj/ELFDumper.cpp?rev=369169&r1=369168&r2=369169&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-readobj/ELFDumper.cpp (original)
+++ llvm/trunk/tools/llvm-readobj/ELFDumper.cpp Fri Aug 16 16:15:40 2019
@@ -4502,7 +4502,7 @@ void GNUStyle<ELFT>::printNotes(const EL
     }
   };
 
-  if (Obj->getHeader()->e_type == ELF::ET_CORE) {
+  if (Obj->getHeader()->e_type == ELF::ET_CORE || Obj->sections()->empty()) {
     for (const auto &P :
          unwrapOrError(this->FileName, Obj->program_headers())) {
       if (P.p_type != PT_NOTE)
@@ -5703,7 +5703,7 @@ void LLVMStyle<ELFT>::printNotes(const E
     }
   };
 
-  if (Obj->getHeader()->e_type == ELF::ET_CORE) {
+  if (Obj->getHeader()->e_type == ELF::ET_CORE || Obj->sections()->empty()) {
     for (const auto &P :
          unwrapOrError(this->FileName, Obj->program_headers())) {
       if (P.p_type != PT_NOTE)