[llvm/Object] - Make ELFObjectFile::getRelocatedSection return Expected<section_iterator>

It returns just a section_iterator currently and have a report_fatal_error call inside.
This change adds a way to return errors and handle them on caller sides.

The patch also changes/improves current users and adds test cases.

Differential revision: https://reviews.llvm.org/D69167

llvm-svn: 375408

include/llvm/Object/ELFObjectFile.h

@@ -288,7 +288,8 @@ protected:
   relocation_iterator section_rel_begin(DataRefImpl Sec) const override;
   relocation_iterator section_rel_end(DataRefImpl Sec) const override;
   std::vector<SectionRef> dynamic_relocation_sections() const override;
-  section_iterator getRelocatedSection(DataRefImpl Sec) const override;
+  Expected<section_iterator>
+  getRelocatedSection(DataRefImpl Sec) const override;
 
   void moveRelocationNext(DataRefImpl &Rel) const override;
   uint64_t getRelocationOffset(DataRefImpl Rel) const override;
@@ -841,7 +842,7 @@ ELFObjectFile<ELFT>::section_rel_end(DataRefImpl Sec) const {
 }
 
 template <class ELFT>
-section_iterator
+Expected<section_iterator>
 ELFObjectFile<ELFT>::getRelocatedSection(DataRefImpl Sec) const {
   if (EF.getHeader()->e_type != ELF::ET_REL)
     return section_end();
@@ -851,10 +852,10 @@ ELFObjectFile<ELFT>::getRelocatedSection(DataRefImpl Sec) const {
   if (Type != ELF::SHT_REL && Type != ELF::SHT_RELA)
     return section_end();
 
-  auto R = EF.getSection(EShdr->sh_info);
-  if (!R)
-    report_fatal_error(errorToErrorCode(R.takeError()).message());
-  return section_iterator(SectionRef(toDRI(*R), this));
+  Expected<const Elf_Shdr *> SecOrErr = EF.getSection(EShdr->sh_info);
+  if (!SecOrErr)
+    return SecOrErr.takeError();
+  return section_iterator(SectionRef(toDRI(*SecOrErr), this));
 }
 
 // Relocations

include/llvm/Object/ObjectFile.h

@@ -130,7 +130,7 @@ public:
   iterator_range<relocation_iterator> relocations() const {
     return make_range(relocation_begin(), relocation_end());
   }
-  section_iterator getRelocatedSection() const;
+  Expected<section_iterator> getRelocatedSection() const;
 
   DataRefImpl getRawDataRefImpl() const;
   const ObjectFile *getObject() const;
@@ -272,7 +272,7 @@ protected:
   virtual bool isBerkeleyData(DataRefImpl Sec) const;
   virtual relocation_iterator section_rel_begin(DataRefImpl Sec) const = 0;
   virtual relocation_iterator section_rel_end(DataRefImpl Sec) const = 0;
-  virtual section_iterator getRelocatedSection(DataRefImpl Sec) const;
+  virtual Expected<section_iterator> getRelocatedSection(DataRefImpl Sec) const;
 
   // Same as above for RelocationRef.
   friend class RelocationRef;
@@ -501,7 +501,7 @@ inline relocation_iterator SectionRef::relocation_end() const {
   return OwningObject->section_rel_end(SectionPimpl);
 }
 
-inline section_iterator SectionRef::getRelocatedSection() const {
+inline Expected<section_iterator> SectionRef::getRelocatedSection() const {
   return OwningObject->getRelocatedSection(SectionPimpl);
 }
 

lib/DebugInfo/DWARF/DWARFContext.cpp

@@ -1527,10 +1527,19 @@ public:
         continue;
 
       StringRef Data;
-      section_iterator RelocatedSection = Section.getRelocatedSection();
+      Expected<section_iterator> SecOrErr = Section.getRelocatedSection();
+      if (!SecOrErr) {
+        ErrorPolicy EP = HandleError(createError(
+            "failed to get relocated section: ", SecOrErr.takeError()));
+        if (EP == ErrorPolicy::Halt)
+          return;
+        continue;
+      }
+
       // Try to obtain an already relocated version of this section.
       // Else use the unrelocated section from the object file. We'll have to
       // apply relocations ourselves later.
+      section_iterator RelocatedSection = *SecOrErr;
       if (!L || !L->getLoadedSectionContents(*RelocatedSection, Data)) {
         Expected<StringRef> E = Section.getContents();
         if (E)

lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp

@@ -348,8 +348,12 @@ RuntimeDyldImpl::loadObjectImpl(const object::ObjectFile &Obj) {
   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
        SI != SE; ++SI) {
     StubMap Stubs;
-    section_iterator RelocatedSection = SI->getRelocatedSection();
 
+    Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
+    if (!RelSecOrErr)
+      return RelSecOrErr.takeError();
+
+    section_iterator RelocatedSection = *RelSecOrErr;
     if (RelocatedSection == SE)
       continue;
 
@@ -648,7 +652,12 @@ unsigned RuntimeDyldImpl::computeSectionStubBufSize(const ObjectFile &Obj,
   unsigned StubBufSize = 0;
   for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
        SI != SE; ++SI) {
-    section_iterator RelSecI = SI->getRelocatedSection();
+
+    Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
+    if (!RelSecOrErr)
+      report_fatal_error(toString(RelSecOrErr.takeError()));
+
+    section_iterator RelSecI = *RelSecOrErr;
     if (!(RelSecI == Section))
       continue;
 

lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp

@@ -606,7 +606,12 @@ Error RuntimeDyldELF::findOPDEntrySection(const ELFObjectFileBase &Obj,
   // .opd entries
   for (section_iterator si = Obj.section_begin(), se = Obj.section_end();
        si != se; ++si) {
-    section_iterator RelSecI = si->getRelocatedSection();
+
+    Expected<section_iterator> RelSecOrErr = si->getRelocatedSection();
+    if (!RelSecOrErr)
+      report_fatal_error(toString(RelSecOrErr.takeError()));
+
+    section_iterator RelSecI = *RelSecOrErr;
     if (RelSecI == Obj.section_end())
       continue;
 
@@ -1871,7 +1876,12 @@ Error RuntimeDyldELF::finalizeLoad(const ObjectFile &Obj,
       for (section_iterator SI = Obj.section_begin(), SE = Obj.section_end();
            SI != SE; ++SI) {
         if (SI->relocation_begin() != SI->relocation_end()) {
-          section_iterator RelocatedSection = SI->getRelocatedSection();
+          Expected<section_iterator> RelSecOrErr = SI->getRelocatedSection();
+          if (!RelSecOrErr)
+            return make_error<RuntimeDyldError>(
+                toString(RelSecOrErr.takeError()));
+
+          section_iterator RelocatedSection = *RelSecOrErr;
           ObjSectionToIDMap::iterator i = SectionMap.find(*RelocatedSection);
           assert (i != SectionMap.end());
           SectionToGOTMap[i->second] = GOTSectionID;

lib/Object/ObjectFile.cpp

@@ -84,7 +84,8 @@ bool ObjectFile::isBerkeleyData(DataRefImpl Sec) const {
   return isSectionData(Sec);
 }
 
-section_iterator ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
+Expected<section_iterator>
+ObjectFile::getRelocatedSection(DataRefImpl Sec) const {
   return section_iterator(SectionRef(Sec, this));
 }
 

test/tools/llvm-cxxdump/broken-reloc-sec.test

@@ -0,0 +1,20 @@
+## Check we report an error when trying to dump an object
+## which has a relocation section that has a broken sh_info
+## field, which is larger than the number of sections.
+
+# RUN: yaml2obj %s -o %t
+# RUN: not llvm-cxxdump %t 2>&1 | FileCheck %s
+# CHECK: error: reading file: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.foo
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-dwarfdump/elf-broken-reloc-target.yaml

@@ -0,0 +1,20 @@
+## Check we report an error if the relocated section identified by the
+## sh_info field of a relocation section is invalid.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-dwarfdump %t 2>&1 | FileCheck %s -DFILE=%t --check-prefix=ERR
+
+# ERR: error: failed to get relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.debug_info
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-objdump/X86/elf-disassemble-relocs.test

@@ -1,8 +1,8 @@
 ## Show that --disassemble + --reloc prints relocations inline and does not dump
 ## the relocation sections.
 
-# RUN: yaml2obj %s -o %t.o
-# RUN: llvm-objdump %t.o -d -r | FileCheck %s --implicit-check-not="RELOCATION RECORDS"
+# RUN: yaml2obj %s --docnum=1 -o %t1.o
+# RUN: llvm-objdump %t1.o -d -r | FileCheck %s --implicit-check-not="RELOCATION RECORDS"
 
 # CHECK:      0: e8 00 00 00 00                callq   0 <.text+0x5>
 # CHECK-NEXT:          0000000000000001:  R_X86_64_PC32        foo-4
@@ -40,3 +40,24 @@ Sections:
 Symbols:
   - Name: foo
   - Name: bar
+
+## Check we report an error if the relocated section identified by the
+## sh_info field of a relocation section is invalid.
+
+# RUN: yaml2obj %s --docnum=2 -o %t2.o
+# RUN: not llvm-objdump %t2.o --disassemble --reloc 2>&1 | FileCheck %s -DFILE=%t2.o --check-prefix=ERR
+
+# ERR: error: '[[FILE]]': section (1): failed to get a relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.debug_info
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-objdump/relocations-elf.test

@@ -74,8 +74,8 @@ Symbols:
 ## Check we report an error if the relocated section identified by the
 ## sh_info field of a relocation section is invalid.
 # RUN: yaml2obj --docnum=2 %s > %t2
-# RUN: not llvm-objdump --reloc %t2 2>&1 | FileCheck %s --check-prefix=ERR
-# ERR: LLVM ERROR: Invalid data was encountered while parsing the file
+# RUN: not llvm-objdump --reloc %t2 2>&1 | FileCheck %s -DFILE=%t2 --check-prefix=ERR
+# ERR: error: '[[FILE]]': section (1): unable to get a relocation target: invalid section index: 255
 
 --- !ELF
 FileHeader:
@@ -86,7 +86,7 @@ FileHeader:
 Sections:
 - Name: .rela.foo
   Type: SHT_RELA
-  Info: 0x255
+  Info: 0xFF
   Relocations:
     - Offset: 0x1
       Type: R_X86_64_NONE

test/tools/llvm-readobj/stack-sizes.test

@@ -641,3 +641,26 @@ Sections:
     Relocations:
       - Offset: 0
         Type:   R_X86_64_64
+
+## Check we report an error when dumping stack sizes if the relocated section
+## identified by the sh_info field is invalid. Here sh_info value is larger than
+## the number of sections.
+
+# RUN: yaml2obj --docnum=13 %s > %t18
+# RUN: not llvm-readelf --stack-sizes %t18 2>&1 | FileCheck %s -DFILE=%t18 --check-prefix=INVALID-TARGET
+# RUN: not llvm-readobj --stack-sizes %t18 2>&1 | FileCheck %s -DFILE=%t18 --check-prefix=INVALID-TARGET
+
+# INVALID-TARGET: error: '[[FILE]]': .rela.stack_sizes: failed to get a relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2MSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name: .rela.stack_sizes
+    Type: SHT_RELA
+    Link: 0
+    Info: 0xFF
+    Relocations: []

tools/llvm-cxxdump/llvm-cxxdump.cpp

@@ -174,7 +174,11 @@ static void dumpCXXData(const ObjectFile *Obj) {
 
   SectionRelocMap.clear();
   for (const SectionRef &Section : Obj->sections()) {
-    section_iterator Sec2 = Section.getRelocatedSection();
+    Expected<section_iterator> ErrOrSec = Section.getRelocatedSection();
+    if (!ErrOrSec)
+      error(ErrOrSec.takeError());
+
+    section_iterator Sec2 = *ErrOrSec;
     if (Sec2 != Obj->section_end())
       SectionRelocMap[*Sec2].push_back(Section);
   }

tools/llvm-objdump/llvm-objdump.cpp

@@ -993,8 +993,17 @@ static size_t countSkippableZeroBytes(ArrayRef<uint8_t> Buf) {
 static std::map<SectionRef, std::vector<RelocationRef>>
 getRelocsMap(object::ObjectFile const &Obj) {
   std::map<SectionRef, std::vector<RelocationRef>> Ret;
+  uint64_t I = (uint64_t)-1;
   for (SectionRef Sec : Obj.sections()) {
-    section_iterator Relocated = Sec.getRelocatedSection();
+    ++I;
+    Expected<section_iterator> RelocatedOrErr = Sec.getRelocatedSection();
+    if (!RelocatedOrErr)
+      reportError(Obj.getFileName(),
+                  "section (" + Twine(I) +
+                      "): failed to get a relocated section: " +
+                      toString(RelocatedOrErr.takeError()));
+
+    section_iterator Relocated = *RelocatedOrErr;
     if (Relocated == Obj.section_end() || !checkSectionFilter(*Relocated).Keep)
       continue;
     std::vector<RelocationRef> &V = Ret[*Relocated];
@@ -1606,11 +1615,17 @@ void printRelocations(const ObjectFile *Obj) {
   // sections. Usually, there is an only one relocation section for
   // each relocated section.
   MapVector<SectionRef, std::vector<SectionRef>> SecToRelSec;
-  for (const SectionRef &Section : ToolSectionFilter(*Obj)) {
+  uint64_t Ndx;
+  for (const SectionRef &Section : ToolSectionFilter(*Obj, &Ndx)) {
     if (Section.relocation_begin() == Section.relocation_end())
       continue;
-    const SectionRef TargetSec = *Section.getRelocatedSection();
-    SecToRelSec[TargetSec].push_back(Section);
+    Expected<section_iterator> SecOrErr = Section.getRelocatedSection();
+    if (!SecOrErr)
+      reportError(Obj->getFileName(),
+                  "section (" + Twine(Ndx) +
+                      "): unable to get a relocation target: " +
+                      toString(SecOrErr.takeError()));
+    SecToRelSec[**SecOrErr].push_back(Section);
   }
 
   for (std::pair<SectionRef, std::vector<SectionRef>> &P : SecToRelSec) {

tools/llvm-readobj/ELFDumper.cpp

@@ -4894,8 +4894,16 @@ void DumpStyle<ELFT>::printRelocatableStackSizes(
     if (SectionType != ELF::SHT_RELA && SectionType != ELF::SHT_REL)
       continue;
 
-    SectionRef Contents = *Sec.getRelocatedSection();
-    const Elf_Shdr *ContentsSec = Obj->getSection(Contents.getRawDataRefImpl());
+    Expected<section_iterator> RelSecOrErr = Sec.getRelocatedSection();
+    if (!RelSecOrErr)
+      reportError(createStringError(object_error::parse_failed,
+                                    "%s: failed to get a relocated section: %s",
+                                    SectionName.data(),
+                                    toString(RelSecOrErr.takeError()).c_str()),
+                  Obj->getFileName());
+
+    const Elf_Shdr *ContentsSec =
+        Obj->getSection((*RelSecOrErr)->getRawDataRefImpl());
     Expected<StringRef> ContentsSectionNameOrErr =
         EF->getSectionName(ContentsSec);
     if (!ContentsSectionNameOrErr) {