[llvm-objcopy][ELF] Add an option to remove notes (#118739)

This adds an option `--remove-note=[name/]type` to selectively delete
notes in ELF files, where `type` is the numeric value of the note type
and `name` is the name of the originator. The name can be omitted, in
which case all notes of the specified type will be removed. For now,
only `SHT_NOTE` sections that are not associated with segments are
handled. The implementation can be extended later as needed.


RFC: https://discourse.llvm.org/t/rfc-llvm-objcopy-feature-for-editing-notes/83491

3 files changed, 61 insertions, 0 deletions

diff --git a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
index 0925fc5..0d20959 100644
--- a/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
+++ b/llvm/tools/llvm-objcopy/ObjcopyOptions.cpp
@@ -538,6 +538,38 @@ static Expected<NewSymbolInfo> parseNewSymbolInfo(StringRef FlagValue) {
   return SI;
 }
 
+static Expected<RemoveNoteInfo> parseRemoveNoteInfo(StringRef FlagValue) {
+  // Parse value given with --remove-note option. The format is:
+  //
+  // [name/]type_id
+  //
+  // where:
+  // <name>    - optional note name. If not given, all notes with the specified
+  //             <type_id> are removed.
+  // <type_id> - note type value, can be decimal or hexadecimal number prefixed
+  //             with 0x.
+  RemoveNoteInfo NI;
+  StringRef TypeIdStr;
+  if (auto Idx = FlagValue.find('/'); Idx != StringRef::npos) {
+    if (Idx == 0)
+      return createStringError(
+          errc::invalid_argument,
+          "bad format for --remove-note, note name is empty");
+    NI.Name = FlagValue.slice(0, Idx);
+    TypeIdStr = FlagValue.substr(Idx + 1);
+  } else {
+    TypeIdStr = FlagValue;
+  }
+  if (TypeIdStr.empty())
+    return createStringError(errc::invalid_argument,
+                             "bad format for --remove-note, missing type_id");
+  if (TypeIdStr.getAsInteger(0, NI.TypeId))
+    return createStringError(errc::invalid_argument,
+                             "bad note type_id for --remove-note: '%s'",
+                             TypeIdStr.str().c_str());
+  return NI;
+}
+
 // Parse input option \p ArgValue and load section data. This function
 // extracts section name and name of the file keeping section data from
 // ArgValue, loads data from the file, and stores section name and data
@@ -1221,6 +1253,29 @@ objcopy::parseObjcopyOptions(ArrayRef<const char *> ArgsArr,
       };
     }
 
+  for (auto *Arg : InputArgs.filtered(OBJCOPY_remove_note)) {
+    Expected<RemoveNoteInfo> NoteInfo = parseRemoveNoteInfo(Arg->getValue());
+    if (!NoteInfo)
+      return NoteInfo.takeError();
+
+    ELFConfig.NotesToRemove.push_back(*NoteInfo);
+  }
+
+  if (!ELFConfig.NotesToRemove.empty()) {
+    if (!Config.ToRemove.empty())
+      return createStringError(
+          errc::invalid_argument,
+          "cannot specify both --remove-note and --remove-section");
+    if (!Config.AddSection.empty())
+      return createStringError(
+          errc::invalid_argument,
+          "cannot specify both --remove-note and --add-section");
+    if (!Config.UpdateSection.empty())
+      return createStringError(
+          errc::invalid_argument,
+          "cannot specify both --remove-note and --update-section");
+  }
+
   if (Config.DecompressDebugSections &&
       Config.CompressionType != DebugCompressionType::None) {
     return createStringError(
diff --git a/llvm/tools/llvm-objcopy/ObjcopyOpts.td b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
index 434b5ff..fbc6a59 100644
--- a/llvm/tools/llvm-objcopy/ObjcopyOpts.td
+++ b/llvm/tools/llvm-objcopy/ObjcopyOpts.td
@@ -297,3 +297,7 @@ defm pad_to
                    "of zero or the value specified by the --gap-fill option. "
                    "This option is only supported for ELF input and binary output">,
       MetaVarName<"address">;
+
+defm remove_note
+    : Eq<"remove-note", "Remove note(s) with <type_id> and optional <name>">,
+      MetaVarName<"[name/]type_id">;
diff --git a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp b/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
index ad3e604..7e708e3 100644
--- a/llvm/tools/llvm-objcopy/llvm-objcopy.cpp
+++ b/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;