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* Reworked writing ELF symbols into a separate class, TElfSymtab, which is also suitable for creating symbol tables in executable and dynamic ELF files.
* Do not write ELF symbols for internal sections (symbol/string table, relocation sections and alike). git-svn-id: trunk@21592 -
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sergei
parent
f2ccc9f593
commit
85f6062e05
@ -50,6 +50,18 @@ interface
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constructor create_ext(aobjdata:TObjData;const Aname:string;Ashtype,Ashflags,Ashlink,Ashinfo:longint;Aalign:shortint;Aentsize:longint);
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end;
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TElfSymtabKind = (esk_obj,esk_exe,esk_dyn);
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TElfSymtab = class(TElfObjSection)
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public
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kind: TElfSymtabKind;
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fstrsec: TObjSection;
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symidx: longint;
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constructor create(aObjData:TObjData;aKind:TElfSymtabKind);reintroduce;
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procedure writeSymbol(objsym:TObjSymbol);
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procedure writeInternalSymbol(astridx:longint;ainfo:byte;ashndx:word);
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end;
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TElfObjData = class(TObjData)
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public
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constructor create(const n:string);override;
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@ -60,21 +72,12 @@ interface
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TElfObjectOutput = class(tObjOutput)
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private
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symtabsect,
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strtabsect,
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symtabsect: TElfSymtab;
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shstrtabsect: TElfObjSection;
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{gotpcsect,
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gotoffsect,
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goTSect,
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plTSect,
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symsect : TElfObjSection;}
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symidx,
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localsyms : longint;
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procedure createrelocsection(s:TElfObjSection;data:TObjData);
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procedure createshstrtab(data:TObjData);
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procedure createsymtab(data: TObjData);
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procedure writesectionheader(s:TElfObjSection);
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procedure write_internal_symbol(astridx:longint;ainfo:byte;ashndx:word);
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procedure section_write_symbol(p:TObject;arg:pointer);
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procedure section_write_sh_string(p:TObject;arg:pointer);
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procedure section_count_sections(p:TObject;arg:pointer);
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@ -928,6 +931,108 @@ implementation
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end;
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{****************************************************************************
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TElfSymtab
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****************************************************************************}
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const
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symsecnames: array[boolean] of string[8] = ('.symtab','.dynsym');
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strsecnames: array[boolean] of string[8] = ('.strtab','.dynstr');
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symsectypes: array[boolean] of longint = (SHT_SYMTAB,SHT_DYNSYM);
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symsecattrs: array[boolean] of longint = (0,SHF_ALLOC);
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constructor TElfSymtab.create(aObjData:TObjData;aKind:TElfSymtabKind);
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var
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dyn:boolean;
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begin
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dyn:=(aKind=esk_dyn);
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create_ext(aObjData,symsecnames[dyn],symsectypes[dyn],symsecattrs[dyn],0,0,sizeof(pint),sizeof(TElfSymbol));
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fstrsec:=TElfObjSection.create_ext(aObjData,strsecnames[dyn],SHT_STRTAB,symsecattrs[dyn],0,0,1,0);
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fstrsec.writestr(#0);
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writezeros(sizeof(TElfSymbol));
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symidx:=1;
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shinfo:=1;
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kind:=aKind;
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end;
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procedure TElfSymtab.writeInternalSymbol(astridx:longint;ainfo:byte;ashndx:word);
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var
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elfsym:TElfSymbol;
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begin
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fillchar(elfsym,sizeof(elfsym),0);
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elfsym.st_name:=astridx;
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elfsym.st_info:=ainfo;
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elfsym.st_shndx:=ashndx;
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inc(symidx);
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inc(shinfo);
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MaybeSwapElfSymbol(elfsym);
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write(elfsym,sizeof(elfsym));
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end;
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procedure TElfSymtab.writeSymbol(objsym:TObjSymbol);
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var
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elfsym:TElfSymbol;
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begin
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fillchar(elfsym,sizeof(elfsym),0);
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{ symbolname, write the #0 separate to overcome 255+1 char not possible }
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elfsym.st_name:=fstrsec.writestr(objsym.name);
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fstrsec.writestr(#0);
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elfsym.st_size:=objsym.size;
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case objsym.bind of
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AB_LOCAL :
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begin
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elfsym.st_value:=objsym.address;
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elfsym.st_info:=STB_LOCAL shl 4;
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inc(shinfo);
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end;
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AB_COMMON :
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begin
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elfsym.st_value:=$10; { ?? should not be hardcoded }
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elfsym.st_info:=STB_GLOBAL shl 4;
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elfsym.st_shndx:=SHN_COMMON;
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end;
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AB_EXTERNAL :
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elfsym.st_info:=STB_GLOBAL shl 4;
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AB_WEAK_EXTERNAL :
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elfsym.st_info:=STB_WEAK shl 4;
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AB_GLOBAL :
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begin
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elfsym.st_value:=objsym.address;
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elfsym.st_info:=STB_GLOBAL shl 4;
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end;
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end;
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if (objsym.bind<>AB_EXTERNAL) {and
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not(assigned(objsym.objsection) and
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not(oso_data in objsym.objsection.secoptions))} then
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begin
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case objsym.typ of
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AT_FUNCTION :
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elfsym.st_info:=elfsym.st_info or STT_FUNC;
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AT_DATA :
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elfsym.st_info:=elfsym.st_info or STT_OBJECT;
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end;
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end;
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if objsym.bind<>AB_COMMON then
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begin
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if kind<>esk_obj then
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begin
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{ TODO }
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end
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else
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begin
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if assigned(objsym.objsection) then
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elfsym.st_shndx:=TElfObjSection(objsym.objsection).secshidx
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else
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elfsym.st_shndx:=SHN_UNDEF;
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objsym.symidx:=symidx;
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end;
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end;
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inc(symidx);
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MaybeSwapElfSymbol(elfsym);
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write(elfsym,sizeof(TElfSymbol));
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end;
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{****************************************************************************
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TElfObjectOutput
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****************************************************************************}
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@ -1080,100 +1185,26 @@ implementation
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end;
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procedure TElfObjectOutput.write_internal_symbol(astridx:longint;ainfo:byte;ashndx:word);
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var
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elfsym : telfsymbol;
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begin
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fillchar(elfsym,sizeof(elfsym),0);
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elfsym.st_name:=astridx;
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elfsym.st_info:=ainfo;
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elfsym.st_shndx:=ashndx;
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inc(symidx);
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inc(localsyms);
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MaybeSwapElfSymbol(elfsym);
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symtabsect.write(elfsym,sizeof(elfsym));
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end;
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procedure TElfObjectOutput.section_write_symbol(p:TObject;arg:pointer);
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begin
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TObjSection(p).secsymidx:=symidx;
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write_internal_symbol(0,STT_SECTION,TElfObjSection(p).secshidx);
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{ Must not write symbols for internal sections like .symtab }
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{ TODO: maybe use inclusive list of section types instead }
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if (TElfObjSection(p).shtype in [SHT_SYMTAB,SHT_STRTAB,SHT_REL,SHT_RELA]) then
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exit;
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TObjSection(p).secsymidx:=symtabsect.symidx;
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symtabsect.writeInternalSymbol(0,STT_SECTION,TElfObjSection(p).secshidx);
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end;
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procedure TElfObjectOutput.createsymtab(data: TObjData);
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procedure WriteSym(objsym:TObjSymbol);
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var
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elfsym : telfsymbol;
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begin
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fillchar(elfsym,sizeof(elfsym),0);
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{ symbolname, write the #0 separate to overcome 255+1 char not possible }
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elfsym.st_name:=strtabsect.Size;
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strtabsect.writestr(objsym.name);
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strtabsect.writestr(#0);
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elfsym.st_size:=objsym.size;
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case objsym.bind of
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AB_LOCAL :
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begin
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elfsym.st_value:=objsym.address;
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elfsym.st_info:=STB_LOCAL shl 4;
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inc(localsyms);
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end;
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AB_COMMON :
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begin
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elfsym.st_value:=$10;
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elfsym.st_info:=STB_GLOBAL shl 4;
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end;
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AB_EXTERNAL :
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elfsym.st_info:=STB_GLOBAL shl 4;
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AB_WEAK_EXTERNAL :
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elfsym.st_info:=STB_WEAK shl 4;
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AB_GLOBAL :
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begin
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elfsym.st_value:=objsym.address;
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elfsym.st_info:=STB_GLOBAL shl 4;
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end;
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end;
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if (objsym.bind<>AB_EXTERNAL) {and
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not(assigned(objsym.objsection) and
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not(oso_data in objsym.objsection.secoptions))} then
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begin
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case objsym.typ of
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AT_FUNCTION :
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elfsym.st_info:=elfsym.st_info or STT_FUNC;
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AT_DATA :
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elfsym.st_info:=elfsym.st_info or STT_OBJECT;
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end;
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end;
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if objsym.bind=AB_COMMON then
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elfsym.st_shndx:=SHN_COMMON
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else
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begin
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if assigned(objsym.objsection) then
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elfsym.st_shndx:=TElfObjSection(objsym.objsection).secshidx
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else
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elfsym.st_shndx:=SHN_UNDEF;
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end;
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objsym.symidx:=symidx;
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inc(symidx);
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MaybeSwapElfSymbol(elfsym);
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symtabsect.write(elfsym,sizeof(elfsym));
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end;
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var
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i : longint;
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objsym : TObjSymbol;
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begin
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with data do
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begin
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symidx:=0;
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localsyms:=0;
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{ empty entry }
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write_internal_symbol(0,0,0);
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{ filename entry }
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write_internal_symbol(1,STT_FILE,SHN_ABS);
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symtabsect.writeInternalSymbol(1,STT_FILE,SHN_ABS);
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{ section }
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ObjSectionList.ForEachCall(@section_write_symbol,nil);
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{ First the Local Symbols, this is required by ELF. The localsyms
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@ -1183,18 +1214,17 @@ implementation
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begin
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objsym:=TObjSymbol(ObjSymbolList[i]);
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if (objsym.bind=AB_LOCAL) and (objsym.typ<>AT_LABEL) then
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WriteSym(objsym);
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symtabsect.WriteSymbol(objsym);
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end;
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{ Global Symbols }
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for i:=0 to ObjSymbolList.Count-1 do
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begin
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objsym:=TObjSymbol(ObjSymbolList[i]);
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if (objsym.bind<>AB_LOCAL) then
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WriteSym(objsym);
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symtabsect.WriteSymbol(objsym);
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end;
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{ update the .symtab section header }
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symtabsect.shlink:=strtabsect.secshidx;
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symtabsect.shinfo:=localsyms;
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symtabsect.shlink:=TElfObjSection(symtabsect.fstrsec).secshidx;
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end;
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end;
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@ -1265,16 +1295,15 @@ implementation
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with data do
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begin
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{ default sections }
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symtabsect:=TElfObjSection.create_ext(data,'.symtab',SHT_SYMTAB,0,0,0,4,sizeof(telfsymbol));
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strtabsect:=TElfObjSection.create_ext(data,'.strtab',SHT_STRTAB,0,0,0,1,0);
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symtabsect:=TElfSymtab.create(data,esk_obj);
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shstrtabsect:=TElfObjSection.create_ext(data,'.shstrtab',SHT_STRTAB,0,0,0,1,0);
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{ "no executable stack" marker for Linux }
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if (target_info.system in systems_linux) and
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not(cs_executable_stack in current_settings.moduleswitches) then
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TElfObjSection.create_ext(data,'.note.GNU-stack',SHT_PROGBITS,0,0,0,1,0);
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{ insert the empty and filename as first in strtab }
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strtabsect.writestr(#0);
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strtabsect.writestr(ExtractFileName(current_module.mainsource)+#0);
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{ insert filename as first in strtab }
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symtabsect.fstrsec.writestr(ExtractFileName(current_module.mainsource));
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symtabsect.fstrsec.writestr(#0);
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{ calc amount of sections we have }
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nsections:=1;
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{ also create the index in the section header table }
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