[PATCH] D105522: [llvm-readobj][XCOFF] Fix the error dumping for the first item of StringTable.

[Esme Yi via Phabricator via llvm-commits]

Esme updated this revision to Diff 357855.
Esme added a comment.
Herald added a subscriber: hiraditya.

Addressed comments.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105522/new/

https://reviews.llvm.org/D105522

Files:
  llvm/lib/Object/XCOFFObjectFile.cpp
  llvm/test/tools/yaml2obj/XCOFF/long-symbol-name.yaml
  llvm/tools/llvm-readobj/ObjDumper.cpp
  llvm/tools/llvm-readobj/ObjDumper.h
  llvm/tools/llvm-readobj/XCOFFDumper.cpp


Index: llvm/tools/llvm-readobj/XCOFFDumper.cpp
===================================================================
--- llvm/tools/llvm-readobj/XCOFFDumper.cpp
+++ llvm/tools/llvm-readobj/XCOFFDumper.cpp
@@ -460,7 +460,9 @@
 void XCOFFDumper::printStringTable() {
   DictScope DS(W, "StringTable");
   StringRef StrTable = Obj.getStringTable();
-  printAsStringList(StrTable);
+  // Print strings from byte 4, since the first three bytes contain the length
+  // (in bytes) of the string table (including the length field).
+  printAsStringList(StrTable, 4);
 }
 
 void XCOFFDumper::printDynamicSymbols() {
Index: llvm/tools/llvm-readobj/ObjDumper.h
===================================================================
--- llvm/tools/llvm-readobj/ObjDumper.h
+++ llvm/tools/llvm-readobj/ObjDumper.h
@@ -110,7 +110,7 @@
 
   virtual void printStackMap() const = 0;
 
-  void printAsStringList(StringRef StringContent);
+  void printAsStringList(StringRef StringContent, size_t StringDataOffset = 0);
 
   void printSectionsAsString(const object::ObjectFile &Obj,
                              ArrayRef<std::string> Sections);
Index: llvm/tools/llvm-readobj/ObjDumper.cpp
===================================================================
--- llvm/tools/llvm-readobj/ObjDumper.cpp
+++ llvm/tools/llvm-readobj/ObjDumper.cpp
@@ -53,9 +53,13 @@
     W << (isPrint(Start[i]) ? static_cast<char>(Start[i]) : '.');
 }
 
-void ObjDumper::printAsStringList(StringRef StringContent) {
+void ObjDumper::printAsStringList(StringRef StringContent,
+                                  size_t StringDataOffset) {
   const uint8_t *StrContent = StringContent.bytes_begin();
-  const uint8_t *CurrentWord = StrContent;
+  // Some formats contain additional metadata at the start which should not be
+  // interpreted as strings. Skip these bytes, but account for them in the
+  // string offsets.
+  const uint8_t *CurrentWord = StrContent + StringDataOffset;
   const uint8_t *StrEnd = StringContent.bytes_end();
 
   while (CurrentWord <= StrEnd) {
Index: llvm/test/tools/yaml2obj/XCOFF/long-symbol-name.yaml
===================================================================
--- llvm/test/tools/yaml2obj/XCOFF/long-symbol-name.yaml
+++ llvm/test/tools/yaml2obj/XCOFF/long-symbol-name.yaml
@@ -2,8 +2,6 @@
 # RUN: yaml2obj %s -o %t
 # RUN: llvm-readobj --symbols --string-table %t | FileCheck %s
 
-## FIXME: The first item of StringTable should be `[     4]   .longname`.
-
 # CHECK:      AddressSize: 32bit
 # CHECK-NEXT: Symbols [
 # CHECK-NEXT:   Symbol {
@@ -26,7 +24,7 @@
 # CHECK-NEXT:   }
 # CHECK-NEXT: ]
 # CHECK-NEXT: StringTable {
-# CHECK-NEXT:   [     3]   ..longname
+# CHECK-NEXT:   [     4]   .longname
 # CHECK-NEXT: }
 
 --- !XCOFF
Index: llvm/lib/Object/XCOFFObjectFile.cpp
===================================================================
--- llvm/lib/Object/XCOFFObjectFile.cpp
+++ llvm/lib/Object/XCOFFObjectFile.cpp
@@ -188,7 +188,9 @@
 }
 
 StringRef XCOFFObjectFile::getStringTable() const {
-  return StringRef(StringTable.Data, StringTable.Size);
+  // If the size is less then 4, then the string table contains no string data.
+  return StringRef(StringTable.Data,
+                   StringTable.Size > 4 ? StringTable.Size : 0);
 }
 
 Expected<StringRef>


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