[llvm-objcopy][ELF] Add an option to remove notes

llvm/include/llvm/ObjCopy/CommonConfig.h

@@ -281,6 +281,11 @@ struct CommonConfig {
 
   SmallVector<std::pair<NameMatcher, llvm::DebugCompressionType>, 0>
       compressSections;
+
+  // ErrorCallback is used to handle recoverable errors. An Error returned
+  // by the callback aborts the execution and is then returned to the caller.
+  // If the callback is not set, the errors are not issued.
+  std::function<Error(Error)> ErrorCallback;
 };
 
 } // namespace objcopy

llvm/lib/ObjCopy/ELF/ELFObjcopy.cpp

@@ -614,7 +614,6 @@ struct RemoveNoteDetail {
   struct DeletedRange {
     uint64_t OldFrom;
     uint64_t OldTo;
-    uint64_t NewPos;
   };
 
   template <class ELFT>
@@ -624,7 +623,6 @@ struct RemoveNoteDetail {
   static std::vector<uint8_t> updateData(ArrayRef<uint8_t> OldData,
                                          ArrayRef<DeletedRange> ToRemove);
 };
-
 } // namespace
 
 template <class ELFT>
@@ -634,7 +632,6 @@ RemoveNoteDetail::findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align,
   LLVM_ELF_IMPORT_TYPES_ELFT(ELFT);
   std::vector<DeletedRange> ToRemove;
   uint64_t CurPos = 0;
-  uint64_t NewPos = 0;
   while (CurPos + sizeof(Elf_Nhdr) <= Data.size()) {
     auto Nhdr = reinterpret_cast<const Elf_Nhdr *>(Data.data() + CurPos);
     size_t FullSize = Nhdr->getSize(Align);
@@ -647,9 +644,7 @@ RemoveNoteDetail::findNotesToRemove(ArrayRef<uint8_t> Data, size_t Align,
                  (NoteInfo.Name.empty() || NoteInfo.Name == Note.getName());
         });
     if (ShouldRemove)
-      ToRemove.push_back({CurPos, CurPos + FullSize, NewPos});
-    else
-      NewPos += FullSize;
+      ToRemove.push_back({CurPos, CurPos + FullSize});
     CurPos += FullSize;
   }
   return ToRemove;
@@ -661,12 +656,11 @@ RemoveNoteDetail::updateData(ArrayRef<uint8_t> OldData,
   std::vector<uint8_t> NewData;
   NewData.reserve(OldData.size());
   uint64_t CurPos = 0;
-  for (auto &RemRange : ToRemove) {
+  for (const DeletedRange &RemRange : ToRemove) {
     if (CurPos < RemRange.OldFrom) {
       auto Slice = OldData.slice(CurPos, RemRange.OldFrom - CurPos);
       NewData.insert(NewData.end(), Slice.begin(), Slice.end());
     }
-    assert(RemRange.NewPos == NewData.size());
     CurPos = RemRange.OldTo;
   }
   if (CurPos < OldData.size()) {
@@ -676,12 +670,33 @@ RemoveNoteDetail::updateData(ArrayRef<uint8_t> OldData,
   return NewData;
 }
 
-static Error removeNote(Object &Obj, endianness Endianness,
-                        ArrayRef<RemoveNoteInfo> NotesToRemove) {
+static Error removeNotes(Object &Obj, endianness Endianness,
+                         ArrayRef<RemoveNoteInfo> NotesToRemove,
+                         function_ref<Error(Error)> ErrorCallback) {
+  // TODO: Support note segments.
+  if (ErrorCallback) {
+    for (Segment &Seg : Obj.segments()) {
+      if (Seg.Type == PT_NOTE) {
+        if (Error E = ErrorCallback(createStringError(
+                errc::not_supported, "note segments are not supported")))
+          return E;
+        break;
+      }
+    }
+  }
   for (auto &Sec : Obj.sections()) {
-    // TODO: Support note sections in segments
-    if (Sec.Type != SHT_NOTE || Sec.ParentSegment || !Sec.hasContents())
+    if (Sec.Type != SHT_NOTE || !Sec.hasContents())
+      continue;
+    // TODO: Support note sections in segments.
+    if (Sec.ParentSegment) {
+      if (ErrorCallback)
+        if (Error E = ErrorCallback(createStringError(
+                errc::not_supported,
+                "cannot remove note(s) from " + Sec.Name +
+                    ": sections in segments are not supported")))
+          return E;
       continue;
+    }
     ArrayRef<uint8_t> OldData = Sec.getContents();
     size_t Align = std::max<size_t>(4, Sec.Align);
     // Note: notes for both 32-bit and 64-bit ELF files use 4-byte words in the
@@ -891,7 +906,8 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
                      : endianness::big;
 
   if (!ELFConfig.NotesToRemove.empty()) {
-    if (Error Err = removeNote(Obj, E, ELFConfig.NotesToRemove))
+    if (Error Err =
+            removeNotes(Obj, E, ELFConfig.NotesToRemove, Config.ErrorCallback))
       return Err;
   }
 

llvm/lib/ObjCopy/ELF/ELFObject.cpp

@@ -2154,27 +2154,25 @@ ELFWriter<ELFT>::ELFWriter(Object &Obj, raw_ostream &Buf, bool WSH,
     : Writer(Obj, Buf), WriteSectionHeaders(WSH && Obj.HadShdrs),
       OnlyKeepDebug(OnlyKeepDebug) {}
 
-Error Object::updateSectionData(std::vector<SecPtr>::iterator It,
-                                ArrayRef<uint8_t> Data) {
-  auto *OldSec = It->get();
-  if (!OldSec->hasContents())
+Error Object::updateSectionData(SecPtr &Sec, ArrayRef<uint8_t> Data) {
+  if (!Sec->hasContents())
     return createStringError(
         errc::invalid_argument,
         "section '%s' cannot be updated because it does not have contents",
-        OldSec->Name.c_str());
+        Sec->Name.c_str());
 
-  if (Data.size() > OldSec->Size && OldSec->ParentSegment)
+  if (Data.size() > Sec->Size && Sec->ParentSegment)
     return createStringError(errc::invalid_argument,
                              "cannot fit data of size %zu into section '%s' "
                              "with size %" PRIu64 " that is part of a segment",
-                             Data.size(), OldSec->Name.c_str(), OldSec->Size);
+                             Data.size(), Sec->Name.c_str(), Sec->Size);
 
-  if (!OldSec->ParentSegment) {
-    *It = std::make_unique<OwnedDataSection>(*OldSec, Data);
+  if (!Sec->ParentSegment) {
+    Sec = std::make_unique<OwnedDataSection>(*Sec, Data);
   } else {
     // The segment writer will be in charge of updating these contents.
-    OldSec->Size = Data.size();
-    UpdatedSections[OldSec] = Data;
+    Sec->Size = Data.size();
+    UpdatedSections[Sec.get()] = Data;
   }
 
   return Error::success();
@@ -2186,14 +2184,14 @@ Error Object::updateSection(StringRef Name, ArrayRef<uint8_t> Data) {
   if (It == Sections.end())
     return createStringError(errc::invalid_argument, "section '%s' not found",
                              Name.str().c_str());
-  return updateSectionData(It, Data);
+  return updateSectionData(*It, Data);
 }
 
 Error Object::updateSectionData(SectionBase &S, ArrayRef<uint8_t> Data) {
   auto It = llvm::find_if(Sections,
                           [&](const SecPtr &Sec) { return Sec.get() == &S; });
   assert(It != Sections.end() && "The section should belong to the object");
-  return updateSectionData(It, Data);
+  return updateSectionData(*It, Data);
 }
 
 Error Object::removeSections(

llvm/lib/ObjCopy/ELF/ELFObject.h

@@ -1168,8 +1168,7 @@ class Object {
     return Sec.Flags & ELF::SHF_ALLOC;
   };
 
-  Error updateSectionData(std::vector<SecPtr>::iterator SecIt,
-                          ArrayRef<uint8_t> Data);
+  Error updateSectionData(SecPtr &Sec, ArrayRef<uint8_t> Data);
 
 public:
   template <class T>

llvm/test/tools/llvm-objcopy/ELF/remove-note-unsupported.test

@@ -0,0 +1,47 @@
+# RUN: yaml2obj --docnum=1 %s -o %t1
+# RUN: llvm-objcopy --remove-note=1 %t1 %t1o 2>&1 | FileCheck %s --check-prefix=NOTE_SEGMENT
+# NOTE_SEGMENT: warning: note segments are not supported
+# NOTE_SEGMENT-NOT: note segments are not supported
+
+--- !ELF
+FileHeader:
+  Class:          ELFCLASS64
+  Data:           ELFDATA2LSB
+  Type:           ET_EXEC
+  Machine:        EM_X86_64
+ProgramHeaders:
+  - Type:         PT_NOTE
+    FirstSec:     .data0
+    LastSec:      .data0
+  - Type:         PT_NOTE
+    FirstSec:     .data1
+    LastSec:      .data1
+Sections:
+  - Name:         .data0
+    Type:         SHT_PROGBITS
+    AddressAlign: 4
+    Content:      "1122334455"
+  - Name:         .data1
+    Type:         SHT_PROGBITS
+    AddressAlign: 4
+    Content:      "1122334455"
+
+# RUN: yaml2obj --docnum=2 %s -o %t2
+# RUN: llvm-objcopy --remove-note=1 %t2 %t2o 2>&1 | FileCheck %s --check-prefix=NOTE_SECTION
+# NOTE_SECTION: warning: cannot remove note(s) from .note: sections in segments are not supported
+
+--- !ELF
+FileHeader:
+  Class:          ELFCLASS64
+  Data:           ELFDATA2LSB
+  Type:           ET_EXEC
+  Machine:        EM_X86_64
+ProgramHeaders:
+  - Type:         PT_LOAD
+    FirstSec:     .note
+    LastSec:      .note
+Sections:
+  - Name:         .note
+    Type:         SHT_NOTE
+    AddressAlign: 4
+    Content:      "1122334455"

llvm/test/tools/llvm-objcopy/ELF/remove-note.test

@@ -1,4 +1,4 @@
-## Check incompatible options
+## Check incompatible options.
 # RUN: not llvm-objcopy --remove-note=1 --remove-section=.test - 2>&1 | FileCheck %s --check-prefix=ERR-REMSEC
 # RUN: not llvm-objcopy --remove-note=1 --add-section=.test=%s - 2>&1 | FileCheck %s --check-prefix=ERR-ADDSEC
 # RUN: not llvm-objcopy --remove-note=1 --update-section=.test=%s - 2>&1 | FileCheck %s --check-prefix=ERR-UPDSEC
@@ -7,7 +7,7 @@
 # ERR-ADDSEC: error: cannot specify both --remove-note and --add-section
 # ERR-UPDSEC: error: cannot specify both --remove-note and --update-section
 
-## Check invalid argument formats
+## Check invalid argument formats.
 # RUN: not llvm-objcopy --remove-note= - 2>&1 | FileCheck %s --check-prefix=ERR-NOTYPEID
 # RUN: not llvm-objcopy --remove-note=CORE/ - 2>&1 | FileCheck %s --check-prefix=ERR-NOTYPEID
 # RUN: not llvm-objcopy --remove-note=/1 - 2>&1 | FileCheck %s --check-prefix=ERR-EMPTYNAME
@@ -20,20 +20,24 @@
 # ERR-INVNUM1: error: bad note type_id for --remove-note: '1/2'
 # ERR-INVNUM2: error: bad note type_id for --remove-note: 'Notanumber'
 
+## Check deleting notes:
+## * --remove-note=1 will remove note "CORE/1" and "LINUX/1",
+## * --remove-note=DUMMY/2 will not remove any notes because there are no notes with this owner,
+## * --remove-note=CORE/3 will remove "CORE/3" but preserve "LINUX/3".
 # RUN: yaml2obj -D ALIGN=8 -D ELFCLASS=64 -D ENDIANNESS=LSB %s -o %t8.64.lsb
 # RUN: llvm-objcopy --remove-note=0x01 --remove-note=DUMMY/2 --remove-note=CORE/0x03 %t8.64.lsb %t8.64.lsb.o
 # RUN: llvm-readobj --segments --sections --notes %t8.64.lsb.o | \
-# RUN:   FileCheck %s -D#SIZE0=32 -D#SIZE1=32
+# RUN:   FileCheck %s -D#SIZE0=32 -D#SIZE1=64
 
 # RUN: yaml2obj -D ALIGN=4 -D ELFCLASS=64 -D ENDIANNESS=MSB %s -o %t4.64.msb
 # RUN: llvm-objcopy --remove-note=0x01 --remove-note=DUMMY/0x02 --remove-note=CORE/3 %t4.64.msb %t4.64.msb.o
 # RUN: llvm-readobj --segments --sections --notes %t4.64.msb.o | \
-# RUN:   FileCheck %s -D#SIZE0=24 -D#SIZE1=24
+# RUN:   FileCheck %s -D#SIZE0=24 -D#SIZE1=48
 
 # RUN: yaml2obj -D ALIGN=4 -D ELFCLASS=32 -D ENDIANNESS=LSB %s -o %t4.32.lsb
 # RUN: llvm-objcopy --remove-note=1 --remove-note=DUMMY/0x02 --remove-note=CORE/3 %t4.32.lsb %t4.32.lsb.o
 # RUN: llvm-readobj --segments --sections --notes %t4.32.lsb.o | \
-# RUN:   FileCheck %s -D#SIZE0=24 -D#SIZE1=24
+# RUN:   FileCheck %s -D#SIZE0=24 -D#SIZE1=48
 
 # CHECK:      Sections [
 # CHECK:        Section {
@@ -70,7 +74,7 @@
 # CHECK-NEXT:         Data size: 0x2
 # CHECK-NEXT:         Type: NT_ARCH
 # CHECK-NEXT:         Description data (
-# CHECK-NEXT:           0000: 0202
+# CHECK-NEXT:           0000: 0201
 # CHECK-NEXT:         )
 # CHECK-NEXT:       }
 # CHECK-NEXT:     ]
@@ -81,11 +85,19 @@
 # CHECK-NEXT:     Size: 0x[[#%X,SIZE1]]
 # CHECK-NEXT:     Notes [
 # CHECK-NEXT:       {
+# CHECK-NEXT:         Owner: LINUX
+# CHECK-NEXT:         Data size: 0x2
+# CHECK-NEXT:         Type: Unknown (0x00000003)
+# CHECK-NEXT:         Description data (
+# CHECK-NEXT:           0000: 0301
+# CHECK-NEXT:         )
+# CHECK-NEXT:       }
+# CHECK-NEXT:       {
 # CHECK-NEXT:         Owner: CORE
 # CHECK-NEXT:         Data size: 0x2
 # CHECK-NEXT:         Type: Unknown (0x00000004)
 # CHECK-NEXT:         Description data (
-# CHECK-NEXT:           0000: 0404
+# CHECK-NEXT:           0000: 0401
 # CHECK-NEXT:         )
 # CHECK-NEXT:       }
 # CHECK-NEXT:     ]
@@ -114,22 +126,25 @@ Sections:
         Desc:   0101
       - Name:   CORE
         Type:   0x02
-        Desc:   0202
+        Desc:   0201
   - Name:         .note1
     Type:         SHT_NOTE
     AddressAlign: [[ALIGN]]
     Notes:
+      - Name:   LINUX
+        Type:   0x03
+        Desc:   0301
       - Name:   CORE
         Type:   0x03
-        Desc:   0303
+        Desc:   0302
       - Name:   CORE
         Type:   0x04
-        Desc:   0404
+        Desc:   0401
   - Name:         .note2
     Type:         SHT_NOTE
     AddressAlign: [[ALIGN]]
     Notes:
       - Name:   LINUX
         Type:   0x01
-        Desc:   0505
+        Desc:   0102
 ...

llvm/tools/llvm-objcopy/llvm-objcopy.cpp

@@ -248,6 +248,8 @@ int llvm_objcopy_main(int argc, char **argv, const llvm::ToolContext &) {
     return 1;
   }
   for (ConfigManager &ConfigMgr : DriverConfig->CopyConfigs) {
+    assert(!ConfigMgr.Common.ErrorCallback);
+    ConfigMgr.Common.ErrorCallback = reportWarning;
     if (Error E = executeObjcopy(ConfigMgr)) {
       logAllUnhandledErrors(std::move(E), WithColor::error(errs(), ToolName));
       return 1;