diff --git a/llvm/test/tools/obj2yaml/ELF/eshnum.yaml b/llvm/test/tools/obj2yaml/ELF/eshnum.yaml new file mode 100644 --- /dev/null +++ b/llvm/test/tools/obj2yaml/ELF/eshnum.yaml @@ -0,0 +1,67 @@ +## Test cases related to the value of the e_shnum field of the ELF header live here. + +## Normally an object that does not have sections has e_shnum == 0. +## Also, e_shnum might be 0, when the the number of entries in the section +## header table is larger than or equal to SHN_LORESERVE (0xff00). In this case +## the real number of entries in the section header table is held in the sh_size +## member of the initial entry in the section header table. + +## In the test case below we have an object that has e_shnum = 0 and the real +## number of sections is written to the sh_size member of the initial entry in +## the section header table. Check that we emit the `EShNum` key properly. + +# RUN: yaml2obj %s -o %t1 +# RUN: obj2yaml %t1 | FileCheck %s --check-prefix=PRESERVE + +# PRESERVE: --- !ELF +# PRESERVE-NEXT: FileHeader: +# PRESERVE-NEXT: Class: ELFCLASS64 +# PRESERVE-NEXT: Data: ELFDATA2LSB +# PRESERVE-NEXT: Type: ET_REL +# PRESERVE-NEXT: EShNum: 0x0 +# PRESERVE-NEXT: Sections: +# PRESERVE-NEXT: - Type: SHT_NULL +# PRESERVE-NEXT: Size: 0x3 +# PRESERVE-NEXT: ... + +--- !ELF +FileHeader: + Class: ELFCLASS64 + Data: ELFDATA2LSB + Type: ET_REL + EShNum: 0x0 + EShOff: [[ESHOFF=]] +Sections: + - Type: SHT_NULL +## 3 sections total: SHT_NULL + 2 implicit sections: .strtab and .shstrtab. + Size: [[SIZE=0x3]] + +## In the test case below we have an object with a non-zero section header table +## file offset and an initial entry in the section header table with sh_size of 0. +## Here we check that we are able to dump such objects properly. + +# RUN: yaml2obj %s -DSIZE=0x0 -o %t2 +# RUN: obj2yaml %t2 | FileCheck %s --check-prefix=NO-SECTIONS + +# NO-SECTIONS: --- !ELF +# NO-SECTIONS-NEXT: FileHeader: +# NO-SECTIONS-NEXT: Class: ELFCLASS64 +# NO-SECTIONS-NEXT: Data: ELFDATA2LSB +# NO-SECTIONS-NEXT: Type: ET_REL +# NO-SECTIONS-NEXT: EShNum: 0x0 +## Note: yaml2obj will create the SHT_NULL section with sh_size = 0 implicitly. +# NO-SECTIONS-NEXT: ... + +## In the test case below we have an object without a section header table and e_shnum == 0. +## Document how we dump it. +## FIXME: we should emit the `SectionHeaderTable` key with `NoHeaders=true` for this case. + +# RUN: yaml2obj %s -DESHOFF=0x0 -o %t3 +# RUN: obj2yaml %t3 | FileCheck %s --check-prefix=NO-HEADERS + +# NO-HEADERS: --- !ELF +# NO-HEADERS-NEXT: FileHeader: +# NO-HEADERS-NEXT: Class: ELFCLASS64 +# NO-HEADERS-NEXT: Data: ELFDATA2LSB +# NO-HEADERS-NEXT: Type: ET_REL +# NO-HEADERS-NEXT: ... diff --git a/llvm/tools/obj2yaml/elf2yaml.cpp b/llvm/tools/obj2yaml/elf2yaml.cpp --- a/llvm/tools/obj2yaml/elf2yaml.cpp +++ b/llvm/tools/obj2yaml/elf2yaml.cpp @@ -237,6 +237,9 @@ ArrayRef Phdrs, std::vector> &V, ArrayRef S) { + if (V.empty()) + return; + uint64_t ExpectedOffset; if (Header.e_phoff > 0) ExpectedOffset = Header.e_phoff + Header.e_phentsize * Header.e_phnum; @@ -289,6 +292,14 @@ Sections = *SectionsOrErr; SectionNames.resize(Sections.size()); + // Normally an object that does not have sections has e_shnum == 0. + // Also, e_shnum might be 0, when the the number of entries in the section + // header table is larger than or equal to SHN_LORESERVE (0xff00). In this + // case the real number of entries is held in the sh_size member of the + // initial entry. We have a section header table when `e_shoff` is not 0. + if (Obj.getHeader().e_shoff != 0 && Obj.getHeader().e_shnum == 0) + Y->Header.EShNum = 0; + // Dump symbols. We need to do this early because other sections might want // to access the deduplicated symbol names that we also create here. const Elf_Shdr *SymTab = nullptr;