[llvm] [llvm-objcopy] Add --change-section-address (PR #98664)

[James Henderson via llvm-commits]

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@@ -745,6 +745,50 @@ static Error handleArgs(const CommonConfig &Config, const ELFConfig &ELFConfig,
     }
   }
 
+  if (!Config.ChangeSectionAddress.empty()) {
+    if (Obj.Type != ELF::ET_REL)
+      return createStringError(
+          object_error::invalid_file_type,
+          "cannot change section address in a non-relocatable file");
+    StringMap<AddressUpdate> SectionsToUpdateAddress;
+    for (const SectionPatternAddressUpdate &PatternUpdate :
+         make_range(Config.ChangeSectionAddress.rbegin(),
+                    Config.ChangeSectionAddress.rend())) {
+      for (SectionBase &Sec : Obj.sections()) {
+        if (PatternUpdate.SectionPattern.matches(Sec.Name) &&
+            SectionsToUpdateAddress.try_emplace(Sec.Name, PatternUpdate.Update)
+                .second) {
+          if (PatternUpdate.Update.Kind == AdjustKind::Subtract &&
+              Sec.Addr < PatternUpdate.Update.Value) {
+            return createStringError(
+                errc::invalid_argument,
+                "address 0x" + Twine::utohexstr(Sec.Addr) +
+                    " cannot be decreased by 0x" +
+                    Twine::utohexstr(PatternUpdate.Update.Value) +
+                    ". The result would underflow");
+          }
+          if (PatternUpdate.Update.Kind == AdjustKind::Add &&
+              Sec.Addr > std::numeric_limits<uint64_t>::max() -
+                             PatternUpdate.Update.Value) {
+            return createStringError(
+                errc::invalid_argument,
+                "address 0x" + Twine::utohexstr(Sec.Addr) +
+                    " cannot be increased by 0x" +
+                    Twine::utohexstr(PatternUpdate.Update.Value) +
+                    ". The result would overflow");
+          }
+          if (PatternUpdate.Update.Kind == AdjustKind::Set) {
----------------
jh7370 wrote:

I think using a `switch` here instead might be a little clearer, now that we're using an `enum` for the `AdjustKind` field. You could also pull this into a separate helper function, so it doesn't need to be heavily nested, probably with the error checks immediately above. I think that'll help the readability of this code.

https://github.com/llvm/llvm-project/pull/98664