[llvm] d88f67b - [llvm-readobj/llvm-readelf] - Reimplement dumping of the SHT_GNU_verdef section.

Georgii Rymar via llvm-commits llvm-commits at lists.llvm.org
Tue Nov 26 06:15:52 PST 2019


Author: Georgii Rymar
Date: 2019-11-26T17:15:39+03:00
New Revision: d88f67bdca7526c2adc3749bb2cfef6b32da971c

URL: https://github.com/llvm/llvm-project/commit/d88f67bdca7526c2adc3749bb2cfef6b32da971c
DIFF: https://github.com/llvm/llvm-project/commit/d88f67bdca7526c2adc3749bb2cfef6b32da971c.diff

LOG: [llvm-readobj/llvm-readelf] - Reimplement dumping of the SHT_GNU_verdef section.

Currently we have following issues:
1) We have 2 different implementations with a different behaviors for GNU/LLVM styles.
2) Errors are either not handled at all or we call report_fatal_error with not helpfull messages.
3) There is no test coverage even for those errors that are reported.

This patch reimplements parsing of the SHT_GNU_verdef section entries
in a single place, adds a few error messages and test coverage.

Differential revision: https://reviews.llvm.org/D70495

Added: 
    

Modified: 
    llvm/test/tools/llvm-readobj/elf-versioninfo.test
    llvm/test/tools/yaml2obj/ELF/verdef-section.yaml
    llvm/tools/llvm-readobj/ELFDumper.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/test/tools/llvm-readobj/elf-versioninfo.test b/llvm/test/tools/llvm-readobj/elf-versioninfo.test
index 27bf302edf9c..c732f7d2a2b6 100644
--- a/llvm/test/tools/llvm-readobj/elf-versioninfo.test
+++ b/llvm/test/tools/llvm-readobj/elf-versioninfo.test
@@ -63,6 +63,7 @@ Sections:
         Names:
           - VERSION2
           - VERSION1
+          - VERSION3
   - Name:         .gnu.version_r
     Type:         SHT_GNU_verneed
     Flags:        [ SHF_ALLOC ]
@@ -193,7 +194,7 @@ DynamicSymbols:
 # LLVM-NEXT:     Index: 3
 # LLVM-NEXT:     Hash: 175630258
 # LLVM-NEXT:     Name: VERSION2
-# LLVM-NEXT:     Predecessor: VERSION1
+# LLVM-NEXT:     Predecessors: [VERSION1, VERSION3]
 # LLVM-NEXT:   }
 # LLVM-NEXT: ]
 # LLVM-NEXT: VersionRequirements [
@@ -273,11 +274,12 @@ DynamicSymbols:
 # GNU-NEXT:    0x0038: Rev: 1  Flags: WEAK  Index: 0  Cnt: 1  Name: VERSION1
 # GNU-NEXT:    0x0054: Rev: 1  Flags: INFO  Index: 0  Cnt: 1  Name: VERSION1
 # GNU-NEXT:    0x0070: Rev: 1  Flags: BASE | WEAK | INFO  Index: 2  Cnt: 1  Name: VERSION1
-# GNU-NEXT:    0x008c: Rev: 1  Flags: <unknown>  Index: 3  Cnt: 2  Name: VERSION2
-# GNU-NEXT:    0x00a8: Parent 1: VERSION1
+# GNU-NEXT:    0x008c: Rev: 1  Flags: <unknown>  Index: 3  Cnt: 3  Name: VERSION2
+# GNU-NEXT:    0x00b0: Parent 1: VERSION1
+# GNU-NEXT:    0x00b0: Parent 2: VERSION3
 # GNU-EMPTY:
 # GNU-NEXT:  Version needs section '.gnu.version_r' contains 2 entries:
-# GNU-NEXT:   Addr: 0000000000000000  Offset: 0x0000fc  Link: 7 (.dynstr)
+# GNU-NEXT:   Addr: 0000000000000000  Offset: 0x000104  Link: 7 (.dynstr)
 # GNU-NEXT:    0x0000: Version: 1  File: verneed1.so.0  Cnt: 5
 # GNU-NEXT:    0x0010:   Name: v1  Flags: BASE  Version: 0
 # GNU-NEXT:    0x0020:   Name: v1  Flags: WEAK  Version: 0
@@ -286,3 +288,237 @@ DynamicSymbols:
 # GNU-NEXT:    0x0050:   Name: v2  Flags: <unknown>  Version: 5
 # GNU-NEXT:    0x0060: Version: 1  File: verneed2.so.0  Cnt: 1
 # GNU-NEXT:    0x0070:   Name: v3  Flags: none  Version: 6
+
+## Check that we report a warning when sh_link references a non-existent section.
+
+# RUN: yaml2obj %s --docnum=2 -o %t2
+# RUN: llvm-readobj -V %t2 2>&1 | FileCheck %s --check-prefix=INVALID-LINK-LLVM -DFILE=%t2
+# RUN: not llvm-readelf -V %t2 2>&1 | FileCheck %s --check-prefix=INVALID-LINK-GNU -DFILE=%t2
+
+# INVALID-LINK-LLVM: warning: '[[FILE]]': invalid section linked to SHT_GNU_verdef section with index 1: invalid section index: 255
+
+## TODO: llvm-readelf should also report a meaningful warning instead of an error.
+# INVALID-LINK-GNU: Version definition
+# INVALID-LINK-GNU: error: '[[FILE]]': invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:    .gnu.version_d
+    Type:    SHT_GNU_verdef
+    Link:    0xFF
+    Info:    0x0
+    Entries: []
+
+## Check that we report a warning when the sh_link field of a SHT_GNU_verdef section references a non-string table section.
+
+# RUN: yaml2obj %s --docnum=3 -o %t3
+# RUN: llvm-readobj -V %t3 2>&1 | FileCheck %s --check-prefix=INVALID-STRING-TABLE -DFILE=%t3
+# RUN: llvm-readelf -V %t3 2>&1 | FileCheck %s --check-prefix=INVALID-STRING-TABLE -DFILE=%t3
+
+# INVALID-STRING-TABLE: warning: '[[FILE]]': invalid string table linked to SHT_GNU_verdef section with index 1: invalid sh_type for string table section [index 0]: expected SHT_STRTAB, but got SHT_NULL
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:    .gnu.version_d
+    Type:    SHT_GNU_verdef
+    Link:    0x0
+    Info:    0x0
+    Entries: []
+
+## Check that we report a warning when we can't read the content of the SHT_GNU_verdef section.
+
+# RUN: yaml2obj %s --docnum=4 -o %t4
+# RUN: llvm-readobj -V %t4 2>&1 | FileCheck %s --check-prefix=INVALID-DATA -DFILE=%t4
+# RUN: llvm-readelf -V %t4 2>&1 | FileCheck %s --check-prefix=INVALID-DATA -DFILE=%t4
+
+# INVALID-DATA: warning: '[[FILE]]': cannot read content of SHT_GNU_verdef section with index 1: section [index 1] has a sh_offset (0xffffffff) + sh_size (0x0) that cannot be represented
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:     .gnu.version_d
+    Type:     SHT_GNU_verdef
+    Link:     .dynstr
+    Info:     0x0
+    Entries:  []
+    ShOffset: 0xFFFFFFFF
+DynamicSymbols:
+  - Name: foo
+
+## Check that we report a warning when a SHT_GNU_verdef section contains a version definition
+## that goes past the end of the section.
+
+# RUN: yaml2obj %s --docnum=5 -o %t5
+# RUN: llvm-readobj -V %t5 2>&1 | FileCheck %s --check-prefix=DEF-PAST-END -DFILE=%t5
+# RUN: llvm-readelf -V %t5 2>&1 | FileCheck %s --check-prefix=DEF-PAST-END -DFILE=%t5
+
+# DEF-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: version definition 1 goes past the end of the section
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:    .gnu.version_d
+    Type:    SHT_GNU_verdef
+    Link:    .dynstr
+    Info:    0x1
+    Entries:
+      - Version:    0
+        Flags:      0
+        VersionNdx: 0
+        Hash:       0
+        Names:
+          - FOO
+    ShSize: 1
+DynamicSymbols:
+  - Name: foo
+
+## Check that we report a warning when a SHT_GNU_verdef section contains a version definition
+## that refers to an auxiliary entry that goes past the end of the section.
+
+# RUN: yaml2obj %s --docnum=6 -o %t6
+# RUN: llvm-readobj -V %t6 2>&1 | FileCheck %s --check-prefix=AUX-PAST-END -DFILE=%t6
+# RUN: llvm-readelf -V %t6 2>&1 | FileCheck %s --check-prefix=AUX-PAST-END -DFILE=%t6
+
+# AUX-PAST-END: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: version definition 1 refers to an auxiliary entry that goes past the end of the section
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:    .gnu.version_d
+    Type:    SHT_GNU_verdef
+    Link:    .dynstr
+    Info:    0x1
+    Entries:
+      - Version:    0
+        Flags:      0
+        VersionNdx: 0
+        Hash:       0
+        Names:
+          - FOO
+    ShSize: 21
+DynamicSymbols:
+  - Name: foo
+
+## Check that we can dump a SHT_GNU_verdef section properly even if it contains version names strings
+## that overrun the linked string table.
+
+# RUN: yaml2obj %s --docnum=7 -o %t7
+# RUN: llvm-readobj -V %t7 2>&1 | FileCheck %s --check-prefix=PAST-STRTAB-END-LLVM --implicit-check-not="warning:" -DFILE=%t7
+# RUN: llvm-readelf -V %t7 2>&1 | FileCheck %s --check-prefix=PAST-STRTAB-END-GNU --implicit-check-not="warning:" -DFILE=%t7
+
+# PAST-STRTAB-END-LLVM:      VersionDefinitions [
+# PAST-STRTAB-END-LLVM-NEXT:   Definition {
+# PAST-STRTAB-END-LLVM-NEXT:     Version: 0
+# PAST-STRTAB-END-LLVM-NEXT:     Flags [ (0x0)
+# PAST-STRTAB-END-LLVM-NEXT:     ]
+# PAST-STRTAB-END-LLVM-NEXT:     Index: 0
+# PAST-STRTAB-END-LLVM-NEXT:     Hash: 0
+# PAST-STRTAB-END-LLVM-NEXT:     Name: <invalid vda_name: 5>
+# PAST-STRTAB-END-LLVM-NEXT:   }
+# PAST-STRTAB-END-LLVM-NEXT: ]
+
+# PAST-STRTAB-END-GNU:      Version definition section '.gnu.version_d' contains 1 entries:
+# PAST-STRTAB-END-GNU-NEXT:  Addr: 0000000000000000  Offset: 0x000040  Link: 2 (.strtab)
+# PAST-STRTAB-END-GNU-NEXT:   0x0000: Rev: 0  Flags: none  Index: 0  Cnt: 1  Name: <invalid vda_name: 5>
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:    .gnu.version_d
+    Type:    SHT_GNU_verdef
+    Link:    .strtab
+    Info:    0x1
+    Entries:
+      - Version:    0
+        Flags:      0
+        VersionNdx: 0
+        Hash:       0
+        Names:
+          - FOO
+  - Name: .strtab
+    Type: SHT_STRTAB
+DynamicSymbols:
+  - Name: BAR
+
+## Check we report a warning when a version definition is not correctly aligned in memory.
+
+# RUN: yaml2obj %s --docnum=8 -o %t8
+# RUN: llvm-readobj -V %t8 2>&1 | FileCheck %s --check-prefix=MISALIGNED-DEF -DFILE=%t8
+# RUN: llvm-readelf -V %t8 2>&1 | FileCheck %s --check-prefix=MISALIGNED-DEF -DFILE=%t8
+
+# MISALIGNED-DEF: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: found a misaligned version definition entry at offset 0x0
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Type: Fill
+    Size: 0x1
+  - Name: .gnu.version_d
+    Type: SHT_GNU_verdef
+    Link: .dynstr
+    Info: 0x1
+    Entries:
+      - Version:    0
+        Flags:      0
+        VersionNdx: 0
+        Hash:       0
+        Names:
+          - FOO
+DynamicSymbols:
+  - Name: foo
+
+## Check we report a warning when an auxiliary entry is not correctly aligned in memory.
+
+# RUN: yaml2obj %s --docnum=9 -o %t9
+# RUN: llvm-readobj -V %t9 2>&1 | FileCheck %s --check-prefix=MISALIGNED-AUX -DFILE=%t9
+# RUN: llvm-readelf -V %t9 2>&1 | FileCheck %s --check-prefix=MISALIGNED-AUX -DFILE=%t9
+
+# MISALIGNED-AUX: warning: '[[FILE]]': invalid SHT_GNU_verdef section with index 1: found a misaligned auxiliary entry at offset 0x13
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_DYN
+  Machine: EM_X86_64
+Sections:
+  - Name:  .gnu.version_d
+    Type:  SHT_GNU_verdef
+    Flags: [ SHF_ALLOC ]
+    Link:  .dynstr
+    Info:  0x1
+## The byte offset to the auxiliary entry is 0x13, i.e. it is not correctly aligned in memory.
+    Content: "0000000000000100000000001300000000000000"
+DynamicSymbols:
+  - Name:    foo
+    Binding: STB_GLOBAL

diff  --git a/llvm/test/tools/yaml2obj/ELF/verdef-section.yaml b/llvm/test/tools/yaml2obj/ELF/verdef-section.yaml
index 9493ab460b70..960acbdb7404 100644
--- a/llvm/test/tools/yaml2obj/ELF/verdef-section.yaml
+++ b/llvm/test/tools/yaml2obj/ELF/verdef-section.yaml
@@ -31,7 +31,7 @@
 # CHECK-NEXT:     Index: 3
 # CHECK-NEXT:     Hash: 108387922
 # CHECK-NEXT:     Name: VERSION_2
-# CHECK-NEXT:     Predecessor: VERSION_3
+# CHECK-NEXT:     Predecessors: [VERSION_3]
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 

diff  --git a/llvm/tools/llvm-readobj/ELFDumper.cpp b/llvm/tools/llvm-readobj/ELFDumper.cpp
index f6975bdb45e8..5127939f0180 100644
--- a/llvm/tools/llvm-readobj/ELFDumper.cpp
+++ b/llvm/tools/llvm-readobj/ELFDumper.cpp
@@ -151,6 +151,24 @@ struct DynRegionInfo {
   }
 };
 
+namespace {
+struct VerdAux {
+  unsigned Offset;
+  std::string Name;
+};
+
+struct VerDef {
+  unsigned Offset;
+  unsigned Version;
+  unsigned Flags;
+  unsigned Ndx;
+  unsigned Cnt;
+  unsigned Hash;
+  std::string Name;
+  std::vector<VerdAux> AuxV;
+};
+} // namespace
+
 template <typename ELFT> class ELFDumper : public ObjDumper {
 public:
   ELFDumper(const object::ELFObjectFile<ELFT> *ObjF, ScopedPrinter &Writer);
@@ -324,8 +342,106 @@ template <typename ELFT> class ELFDumper : public ObjDumper {
   const DynRegionInfo &getDynamicTableRegion() const { return DynamicTable; }
   const Elf_Hash *getHashTable() const { return HashTable; }
   const Elf_GnuHash *getGnuHashTable() const { return GnuHashTable; }
+
+  Expected<std::vector<VerDef>>
+  getVersionDefinitions(const Elf_Shdr *Sec) const;
 };
 
+template <class ELFT>
+Expected<std::vector<VerDef>>
+ELFDumper<ELFT>::getVersionDefinitions(const Elf_Shdr *Sec) const {
+  const ELFFile<ELFT> *Obj = ObjF->getELFFile();
+  unsigned SecNdx = Sec - &cantFail(Obj->sections()).front();
+
+  Expected<const Elf_Shdr *> StrTabSecOrErr = Obj->getSection(Sec->sh_link);
+  if (!StrTabSecOrErr)
+    return createError(
+        "invalid section linked to SHT_GNU_verdef section with index " +
+        Twine(SecNdx) + ": " + toString(StrTabSecOrErr.takeError()));
+
+  Expected<StringRef> StrTabOrErr = Obj->getStringTable(*StrTabSecOrErr);
+  if (!StrTabOrErr)
+    return createError(
+        "invalid string table linked to SHT_GNU_verdef section with index " +
+        Twine(SecNdx) + ": " + toString(StrTabOrErr.takeError()));
+
+  Expected<ArrayRef<uint8_t>> ContentsOrErr = Obj->getSectionContents(Sec);
+  if (!ContentsOrErr)
+    return createError(
+        "cannot read content of SHT_GNU_verdef section with index " +
+        Twine(SecNdx) + ": " + toString(ContentsOrErr.takeError()));
+
+  const uint8_t *Start = ContentsOrErr->data();
+  const uint8_t *End = Start + ContentsOrErr->size();
+
+  auto ExtractNextAux = [&](const uint8_t *&VerdauxBuf,
+                            unsigned VerDefNdx) -> Expected<VerdAux> {
+    if (VerdauxBuf + sizeof(Elf_Verdaux) > End)
+      return createError("invalid SHT_GNU_verdef section with index " +
+                         Twine(SecNdx) + ": version definition " +
+                         Twine(VerDefNdx) +
+                         " refers to an auxiliary entry that goes past the end "
+                         "of the section");
+
+    auto *Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
+    VerdauxBuf += Verdaux->vda_next;
+
+    VerdAux Aux;
+    Aux.Offset = VerdauxBuf - Start;
+    if (Verdaux->vda_name <= StrTabOrErr->size())
+      Aux.Name = StrTabOrErr->drop_front(Verdaux->vda_name);
+    else
+      Aux.Name = "<invalid vda_name: " + to_string(Verdaux->vda_name) + ">";
+    return Aux;
+  };
+
+  std::vector<VerDef> Ret;
+  const uint8_t *VerdefBuf = Start;
+  for (unsigned I = 1; I <= /*VerDefsNum=*/Sec->sh_info; ++I) {
+    if (VerdefBuf + sizeof(Elf_Verdef) > End)
+      return createError("invalid SHT_GNU_verdef section with index " +
+                         Twine(SecNdx) + ": version definition " + Twine(I) +
+                         " goes past the end of the section");
+
+    if (uintptr_t(VerdefBuf) % sizeof(uint32_t) != 0)
+      return createError(
+          "invalid SHT_GNU_verdef section with index " + Twine(SecNdx) +
+          ": found a misaligned version definition entry at offset 0x" +
+          Twine::utohexstr(VerdefBuf - Start));
+
+    const Elf_Verdef *D = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
+    VerDef &VD = *Ret.emplace(Ret.end());
+    VD.Offset = VerdefBuf - Start;
+    VD.Version = D->vd_version;
+    VD.Flags = D->vd_flags;
+    VD.Ndx = D->vd_ndx;
+    VD.Cnt = D->vd_cnt;
+    VD.Hash = D->vd_hash;
+
+    const uint8_t *VerdauxBuf = VerdefBuf + D->vd_aux;
+    for (unsigned J = 0; J < D->vd_cnt; ++J) {
+      if (uintptr_t(VerdauxBuf) % sizeof(uint32_t) != 0)
+        return createError("invalid SHT_GNU_verdef section with index " +
+                           Twine(SecNdx) +
+                           ": found a misaligned auxiliary entry at offset 0x" +
+                           Twine::utohexstr(VerdauxBuf - Start));
+
+      Expected<VerdAux> AuxOrErr = ExtractNextAux(VerdauxBuf, I);
+      if (!AuxOrErr)
+        return AuxOrErr.takeError();
+
+      if (J == 0)
+        VD.Name = AuxOrErr->Name;
+      else
+        VD.AuxV.push_back(*AuxOrErr);
+    }
+
+    VerdefBuf += D->vd_next;
+  }
+
+  return Ret;
+}
+
 template <class ELFT>
 void ELFDumper<ELFT>::printSymbolsHelper(bool IsDynamic) const {
   StringRef StrTable, SymtabName;
@@ -3901,42 +4017,26 @@ void GNUStyle<ELFT>::printVersionDefinitionSection(const ELFFile<ELFT> *Obj,
   if (!Sec)
     return;
 
-  unsigned VerDefsNum = Sec->sh_info;
-  printGNUVersionSectionProlog(OS, "Version definition", VerDefsNum, Obj, Sec,
+  printGNUVersionSectionProlog(OS, "Version definition", Sec->sh_info, Obj, Sec,
                                this->FileName);
 
-  const Elf_Shdr *StrTabSec =
-      unwrapOrError(this->FileName, Obj->getSection(Sec->sh_link));
-  StringRef StringTable(
-      reinterpret_cast<const char *>(Obj->base() + StrTabSec->sh_offset),
-      (size_t)StrTabSec->sh_size);
-
-  const uint8_t *VerdefBuf =
-      unwrapOrError(this->FileName, Obj->getSectionContents(Sec)).data();
-  const uint8_t *Begin = VerdefBuf;
-
-  while (VerDefsNum--) {
-    const Elf_Verdef *Verdef = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
-    OS << format("  0x%04x: Rev: %u  Flags: %s  Index: %u  Cnt: %u",
-                 VerdefBuf - Begin, (unsigned)Verdef->vd_version,
-                 versionFlagToString(Verdef->vd_flags).c_str(),
-                 (unsigned)Verdef->vd_ndx, (unsigned)Verdef->vd_cnt);
-
-    const uint8_t *VerdauxBuf = VerdefBuf + Verdef->vd_aux;
-    const Elf_Verdaux *Verdaux =
-        reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
-    OS << format("  Name: %s\n",
-                 StringTable.drop_front(Verdaux->vda_name).data());
-
-    for (unsigned I = 1; I < Verdef->vd_cnt; ++I) {
-      VerdauxBuf += Verdaux->vda_next;
-      Verdaux = reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
-      OS << format("  0x%04x: Parent %u: %s\n", VerdauxBuf - Begin, I,
-                   StringTable.drop_front(Verdaux->vda_name).data());
-    }
+  Expected<std::vector<VerDef>> V = this->dumper()->getVersionDefinitions(Sec);
+  if (!V) {
+    this->reportUniqueWarning(V.takeError());
+    return;
+  }
 
-    VerdefBuf += Verdef->vd_next;
+  for (const VerDef &Def : *V) {
+    OS << format("  0x%04x: Rev: %u  Flags: %s  Index: %u  Cnt: %u  Name: %s\n",
+                 Def.Offset, Def.Version,
+                 versionFlagToString(Def.Flags).c_str(), Def.Ndx, Def.Cnt,
+                 Def.Name.data());
+    unsigned I = 0;
+    for (const VerdAux &Aux : Def.AuxV)
+      OS << format("  0x%04x: Parent %u: %s\n", Aux.Offset, ++I,
+                   Aux.Name.data());
   }
+
   OS << '\n';
 }
 
@@ -5713,44 +5813,25 @@ void LLVMStyle<ELFT>::printVersionDefinitionSection(const ELFFile<ELFT> *Obj,
   if (!Sec)
     return;
 
-  const uint8_t *SecStartAddress =
-      reinterpret_cast<const uint8_t *>(Obj->base() + Sec->sh_offset);
-  const uint8_t *SecEndAddress = SecStartAddress + Sec->sh_size;
-  const uint8_t *VerdefBuf = SecStartAddress;
-  const Elf_Shdr *StrTab =
-      unwrapOrError(this->FileName, Obj->getSection(Sec->sh_link));
-
-  unsigned VerDefsNum = Sec->sh_info;
-  while (VerDefsNum--) {
-    if (VerdefBuf + sizeof(Elf_Verdef) > SecEndAddress)
-      // FIXME: report_fatal_error is not a good way to report error. We should
-      // emit a parsing error here and below.
-      report_fatal_error("invalid offset in the section");
+  Expected<std::vector<VerDef>> V = this->dumper()->getVersionDefinitions(Sec);
+  if (!V) {
+    this->reportUniqueWarning(V.takeError());
+    return;
+  }
 
-    const Elf_Verdef *Verdef = reinterpret_cast<const Elf_Verdef *>(VerdefBuf);
+  for (const VerDef &D : *V) {
     DictScope Def(W, "Definition");
-    W.printNumber("Version", Verdef->vd_version);
-    W.printFlags("Flags", Verdef->vd_flags, makeArrayRef(SymVersionFlags));
-    W.printNumber("Index", Verdef->vd_ndx);
-    W.printNumber("Hash", Verdef->vd_hash);
-    W.printString("Name", StringRef(reinterpret_cast<const char *>(
-                              Obj->base() + StrTab->sh_offset +
-                              Verdef->getAux()->vda_name)));
-    if (!Verdef->vd_cnt)
-      report_fatal_error("at least one definition string must exist");
-    if (Verdef->vd_cnt > 2)
-      report_fatal_error("more than one predecessor is not expected");
-
-    if (Verdef->vd_cnt == 2) {
-      const uint8_t *VerdauxBuf =
-          VerdefBuf + Verdef->vd_aux + Verdef->getAux()->vda_next;
-      const Elf_Verdaux *Verdaux =
-          reinterpret_cast<const Elf_Verdaux *>(VerdauxBuf);
-      W.printString("Predecessor",
-                    StringRef(reinterpret_cast<const char *>(
-                        Obj->base() + StrTab->sh_offset + Verdaux->vda_name)));
-    }
-    VerdefBuf += Verdef->vd_next;
+    W.printNumber("Version", D.Version);
+    W.printFlags("Flags", D.Flags, makeArrayRef(SymVersionFlags));
+    W.printNumber("Index", D.Ndx);
+    W.printNumber("Hash", D.Hash);
+    W.printString("Name", D.Name.c_str());
+
+    if (D.AuxV.empty())
+      continue;
+    W.printList(
+        "Predecessors", D.AuxV,
+        [](raw_ostream &OS, const VerdAux &Aux) { OS << Aux.Name.c_str(); });
   }
 }
 


        


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