[llvm-readobj] - Don't stop dumping when the name of a relocation section can't be read.

[grimar]

Summary

This removes undesired unwrapOrError calls from printRelocations() methods.

[jhenderson]

llvm/tools/llvm-readobj/ELFDumper.cpp

6135–6141

This code looks like something that could be shared both with the GNU style and possibly even more widely with other places getting section names.

[grimar]

I'll update it after we land D84526 and D83935.

[grimar]

• Addressed review comments (introduced getPrintableSectionName).

llvm/tools/llvm-readobj/ELFDumper.cpp

6135–6141

Done.

[jhenderson]

LGTM, thanks!

llvm/test/tools/llvm-readobj/ELF/relocations.test

FileHeader:
   Class:   ELFCLASS64
   Data:    ELFDATA2LSB
   Type:    ET_REL
   Machine: EM_X86_64
 Sections:
   - Name: .text
     Type: SHT_PROGBITS
     Content: '00FFFFFFFF020000001234567890ABCDEF'
-  - Name: .rel.text
-    Type: SHT_REL
-    Info: .text
+  - Name:   .rel.text
+    Type:   SHT_REL
+    Info:   .text
+    ShName: [[SHNAME=DEFAULT]]
     Relocations:
       - Symbol: rel_0
         Type:   R_X86_64_NONE
       - Offset: 0x1
         Symbol: rel_neg
         Type:   R_X86_64_PC32
       - Offset: 0x5
         Symbol: rel_pos
         Type:   R_X86_64_PLT32
       - Offset: 0x9
         Symbol: rel_64
         Type:   R_X86_64_64
   - Name: .rela.text
     Type: SHT_RELA
     Info: .text
+    ShName: [[SHNAME=DEFAULT]]
     Relocations:
       - Symbol: rela_0
         Type:   R_X86_64_NONE
         Addend: 0
       - Offset: 0x1
         Symbol: rela_neg
         Type:   R_X86_64_PC32
         Addend: -1
- Name:    rela_pos
     Section: .text
     Value:   2
   - Name:    rela_minneg
     Section: .text
     Value:   3
   - Name:    rela_maxpos
     Section: .text
     Value:   0xFFFFFFFF
+
+## Check we report a warning when the name of a relocation section can't be read. Check we continue dumping.
+# RUN: yaml2obj %s --docnum=1 -DSHNAME=0xffffffff -o %tshname
+# RUN: llvm-readobj --relocs %tshname 2>&1 | FileCheck %s -DFILE=%tshname --check-prefix=LLVM-SHNAME
+# RUN: llvm-readelf --relocs %tshname 2>&1 | FileCheck %s -DFILE=%tshname --check-prefix=GNU-SHNAME
+
+# LLVM-SHNAME:      Relocations [
+# LLVM-SHNAME-NEXT: warning: '[[FILE]]': unable to get the name of SHT_REL section with index 2: a section [index 2] has an invalid sh_name (0xffffffff) offset which goes past the end of the section name string table
+# LLVM-SHNAME-NEXT:   Section (2) <?> {
+# LLVM-SHNAME-NEXT:     0x0 R_X86_64_NONE rel_0 0x0
+# LLVM-SHNAME-NEXT:     0x1 R_X86_64_PC32 rel_neg 0x0
+# LLVM-SHNAME-NEXT:     0x5 R_X86_64_PLT32 rel_pos 0x0
+# LLVM-SHNAME-NEXT:     0x9 R_X86_64_64 rel_64 0x0
+# LLVM-SHNAME-NEXT:   }
+# LLVM-SHNAME-NEXT: warning: '[[FILE]]': unable to get the name of SHT_RELA section with index 3: a section [index 3] has an invalid sh_name (0xffffffff) offset which goes past the end of the section name string table
+# LLVM-SHNAME-NEXT:   Section (3) <?> {
+# LLVM-SHNAME-NEXT:     0x0 R_X86_64_NONE rela_0 0x0
+# LLVM-SHNAME-NEXT:     0x1 R_X86_64_PC32 rela_neg 0xFFFFFFFFFFFFFFFF
+# LLVM-SHNAME-NEXT:     0x5 R_X86_64_PLT32 rela_pos 0x2
+# LLVM-SHNAME-NEXT:     0xFFFFFFFFFFFFFFFF R_X86_64_64 rela_minneg 0x8000000000000000
+# LLVM-SHNAME-NEXT:     0x9 R_X86_64_32S rela_maxpos 0x7FFFFFFFFFFFFFFF
+# LLVM-SHNAME-NEXT:   }
+# LLVM-SHNAME-NEXT: ]
+
+# GNU-SHNAME:      warning: '[[FILE]]': unable to get the name of SHT_REL section with index 2: a section [index 2] has an invalid sh_name (0xffffffff) offset which goes past the end of the section name string table
+# GNU-SHNAME:      Relocation section '<?>' at offset 0x51 contains 4 entries:
+# GNU-SHNAME-NEXT:     Offset             Info             Type               Symbol's Value  Symbol's Name
+# GNU-SHNAME-NEXT: 0000000000000000  0000000100000000 R_X86_64_NONE          0000000000000000 rel_0
+# GNU-SHNAME-NEXT: 0000000000000001  0000000200000002 R_X86_64_PC32          0000000000000001 rel_neg
+# GNU-SHNAME-NEXT: 0000000000000005  0000000300000004 R_X86_64_PLT32         0000000000000002 rel_pos
+# GNU-SHNAME-NEXT: 0000000000000009  0000000400000001 R_X86_64_64            ffffffffffffffff rel_64
+# GNU-SHNAME:      warning: '[[FILE]]': unable to get the name of SHT_RELA section with index 3: a section [index 3] has an invalid sh_name (0xffffffff) offset which goes past the end of the section name string table
+# GNU-SHNAME:      Relocation section '<?>' at offset 0x91 contains 5 entries:
+# GNU-SHNAME-NEXT:     Offset             Info             Type       Symbol's Value  Symbol's Name + Addend
+# GNU-SHNAME-NEXT: 0000000000000000  0000000500000000 R_X86_64_NONE  0000000000000000 rela_0 + 0
+# GNU-SHNAME-NEXT: 0000000000000001  0000000600000002 R_X86_64_PC32  0000000000000001 rela_neg - 1
+# GNU-SHNAME-NEXT: 0000000000000005  0000000700000004 R_X86_64_PLT32 0000000000000002 rela_pos + 2
+# GNU-SHNAME-NEXT: ffffffffffffffff  0000000800000001 R_X86_64_64    0000000000000003 rela_minneg - 8000000000000000
+# GNU-SHNAME-NEXT: 0000000000000009  000000090000000b R_X86_64_32S   ffffffffffffffff rela_maxpos + 7fffffffffffffff

llvm/tools/llvm-readobj/ELFDumper.cpp

 
 template <class ELFT> void GNUStyle<ELFT>::printRelocations(const ELFO *Obj) {
   bool HasRelocSections = false;
   for (const Elf_Shdr &Sec : cantFail(Obj->sections())) {
     if (!isRelocationSec<ELFT>(Sec))
       continue;
     HasRelocSections = true;
 
-    StringRef Name = unwrapOrError(this->FileName, Obj->getSectionName(&Sec));
     unsigned Entries;
     // Android's packed relocation section needs to be unpacked first
     // to get the actual number of entries.
     if (Sec.sh_type == ELF::SHT_ANDROID_REL ||
         Sec.sh_type == ELF::SHT_ANDROID_RELA) {
       Entries = unwrapOrError(this->FileName, Obj->android_relas(&Sec)).size();
     } else if (!opts::RawRelr && (Sec.sh_type == ELF::SHT_RELR ||
                                   Sec.sh_type == ELF::SHT_ANDROID_RELR)) {
       Elf_Relr_Range Relrs = unwrapOrError(this->FileName, Obj->relrs(&Sec));
       Entries = unwrapOrError(this->FileName, Obj->decode_relrs(Relrs)).size();
     } else {
       Entries = Sec.getEntityCount();
     }
 
     uintX_t Offset = Sec.sh_offset;
+    StringRef Name = "<?>";
+    if (Expected<StringRef> NameOrErr = Obj->getSectionName(&Sec))
+      Name = *NameOrErr;
+    else
+      this->reportUniqueWarning(createError("unable to get the name of " +
+                                            describe(Obj, Sec) + ": " +
+                                            toString(NameOrErr.takeError())));
     OS << "\nRelocation section '" << Name << "' at offset 0x"
        << to_hexString(Offset, false) << " contains " << Entries
        << " entries:\n";
     printRelocHeader(Sec.sh_type);
     this->printRelocationsHelper(Obj, Sec);
   }
   if (!HasRelocSections)
     OS << "\nThere are no relocations in this file.\n";

 
 template <class ELFT> void LLVMStyle<ELFT>::printRelocations(const ELFO *Obj) {
   ListScope D(W, "Relocations");
 
   for (const Elf_Shdr &Sec : cantFail(Obj->sections())) {
     if (!isRelocationSec<ELFT>(Sec))
       continue;
 
-    StringRef Name = unwrapOrError(this->FileName, Obj->getSectionName(&Sec));
+    StringRef Name = "<?>";
+    if (Expected<StringRef> NameOrErr = Obj->getSectionName(&Sec))
+      Name = *NameOrErr;
+    else
+      this->reportUniqueWarning(createError("unable to get the name of " +
+                                            describe(Obj, Sec) + ": " +
+                                            toString(NameOrErr.takeError())));
+
     unsigned SecNdx = &Sec - &cantFail(Obj->sections()).front();
     W.startLine() << "Section (" << SecNdx << ") " << Name << " {\n";
     W.indent();
     this->printRelocationsHelper(Obj, Sec);
     W.unindent();
     W.startLine() << "}\n";
   }
 }