[PATCH] D62179: [llvm-readelf] - Allow dumping of the .dynamic section even if there is no PT_DYNAMIC header.

[George Rimar via Phabricator via llvm-commits]

grimar updated this revision to Diff 200667.
grimar added a comment.

- Updated comments.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D62179/new/

https://reviews.llvm.org/D62179

Files:
  test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
  tools/llvm-readobj/ELFDumper.cpp


Index: tools/llvm-readobj/ELFDumper.cpp
===================================================================
--- tools/llvm-readobj/ELFDumper.cpp
+++ tools/llvm-readobj/ELFDumper.cpp
@@ -1331,6 +1331,7 @@
 
 template <typename ELFT>
 void ELFDumper<ELFT>::loadDynamicTable(const ELFFile<ELFT> *Obj) {
+  // Try to locate the PT_DYNAMIC header.
   const Elf_Phdr *DynamicPhdr = nullptr;
   for (const Elf_Phdr &Phdr : unwrapOrError(Obj->program_headers())) {
     if (Phdr.p_type != ELF::PT_DYNAMIC)
@@ -1339,11 +1340,6 @@
     break;
   }
 
-  // We do not want to dump dynamic section if we have no PT_DYNAMIC header.
-  // This matches GNU's behavior.
-  if (!DynamicPhdr)
-    return;
-
   // Try to locate the .dynamic section in the sections header table.
   const Elf_Shdr *DynamicSec = nullptr;
   for (const Elf_Shdr &Sec : unwrapOrError(Obj->sections())) {
@@ -1358,9 +1354,16 @@
   // Ignore sh_entsize and use the expected value for entry size explicitly.
   // This allows us to dump the dynamic sections with a broken sh_entsize
   // field.
-  if (DynamicSec)
+  if (DynamicSec) {
     DynamicTable = checkDRI({ObjF->getELFFile()->base() + DynamicSec->sh_offset,
                              DynamicSec->sh_size, sizeof(Elf_Dyn)});
+    parseDynamicTable();
+  }
+
+  // If we have a PT_DYNAMIC header, we will either check the found dynamic
+  // section or take the dynamic table data directly from the header.
+  if (!DynamicPhdr)
+    return;
 
   if (DynamicPhdr->p_offset + DynamicPhdr->p_filesz >
       ObjF->getMemoryBufferRef().getBufferSize())
@@ -1374,7 +1377,6 @@
   }
 
   StringRef Name = unwrapOrError(Obj->getSectionName(DynamicSec));
-
   if (DynamicSec->sh_addr + DynamicSec->sh_size >
           DynamicPhdr->p_vaddr + DynamicPhdr->p_memsz ||
       DynamicSec->sh_addr < DynamicPhdr->p_vaddr)
@@ -1386,8 +1388,6 @@
     reportWarning("The SHT_DYNAMIC section '" + Name +
                   "' is not at the start of "
                   "PT_DYNAMIC segment");
-
-  parseDynamicTable();
 }
 
 template <typename ELFT>
Index: test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
===================================================================
--- test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
+++ test/tools/llvm-readobj/elf-dynamic-no-pt-dynamic.test
@@ -1,16 +1,23 @@
-# Show that no dumping occurs if there is no PT_DYNAMIC header.
+## Show that dumping occurs even if there is no PT_DYNAMIC header.
+## This is inconsistent with the GNU behavior, but seems to be more reasonable.
 # RUN: yaml2obj %s -o %t.no-phdr
 # RUN: llvm-readobj --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=LLVM
-# RUN: llvm-readelf --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=GNU --allow-empty
+# RUN: llvm-readelf --dynamic-table %t.no-phdr | FileCheck %s --check-prefix=GNU
 
 # LLVM:      File: {{.*}}.no-phdr
 # LLVM-NEXT: Format: ELF64-x86-64
 # LLVM-NEXT: Arch: x86_64
 # LLVM-NEXT: AddressSize: 64bit
 # LLVM-NEXT: LoadName:{{ *}}
-# LLVM-NOT:  {{.}}
+# LLVM-NEXT: DynamicSection [ (1 entries)
+# LLVM-NEXT:   Tag                Type Name/Value
+# LLVM-NEXT:   0x0000000000000000 NULL 0x0
+# LLVM-NEXT: ]
 
-# GNU-NOT: {{.}}
+# GNU:      DynamicSection [ (1 entries)
+# GNU-NEXT:   Tag                Type Name/Value
+# GNU-NEXT:   0x0000000000000000 NULL 0x0
+# GNU-NEXT: ]
 
 --- !ELF
 FileHeader:


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