[llvm-ar][libObject] Fix relative paths when nesting thin archives.

Summary:
When adding one thin archive to another, we currently chop off the relative path to the flattened members. For instance, when adding `foo/child.a` (which contains `x.txt`) to `parent.a`, when flattening it we should add it as `foo/x.txt` (which exists) instead of `x.txt` (which does not exist).

As a note, this also undoes the `IsNew` parameter of handling relative paths in r288280. The unit test there still passes.

This was reported as part of testing the kernel build with llvm-ar: https://patchwork.kernel.org/patch/10767545/ (see the second point).

Reviewers: mstorsjo, pcc, ruiu, davide, david2050, inglorion

Reviewed By: ruiu

Subscribers: void, jdoerfert, tpimh, mgorny, hans, nickdesaulniers, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57842

llvm-svn: 353995

1 files changed, 48 insertions, 64 deletions

diff --git a/llvm/lib/Object/ArchiveWriter.cpp b/llvm/lib/Object/ArchiveWriter.cpp
index d27233ec2f4..4116ed4628e 100644
--- a/llvm/lib/Object/ArchiveWriter.cpp
+++ b/llvm/lib/Object/ArchiveWriter.cpp
@@ -48,7 +48,6 @@ NewArchiveMember::getOldMember(const object::Archive::Child &OldMember,
     return BufOrErr.takeError();
 
   NewArchiveMember M;
-  assert(M.IsNew == false);
   M.Buf = MemoryBuffer::getMemBuffer(*BufOrErr, false);
   M.MemberName = M.Buf->getBufferIdentifier();
   if (!Deterministic) {
@@ -98,7 +97,6 @@ Expected<NewArchiveMember> NewArchiveMember::getFile(StringRef FileName,
     return errorCodeToError(std::error_code(errno, std::generic_category()));
 
   NewArchiveMember M;
-  M.IsNew = true;
   M.Buf = std::move(*MemberBufferOrErr);
   M.MemberName = M.Buf->getBufferIdentifier();
   if (!Deterministic) {
@@ -191,35 +189,6 @@ static bool useStringTable(bool Thin, StringRef Name) {
   return Thin || Name.size() >= 16 || Name.contains('/');
 }
 
-// Compute the relative path from From to To.
-static std::string computeRelativePath(StringRef From, StringRef To) {
-  if (sys::path::is_absolute(From) || sys::path::is_absolute(To))
-    return To;
-
-  StringRef DirFrom = sys::path::parent_path(From);
-  auto FromI = sys::path::begin(DirFrom);
-  auto ToI = sys::path::begin(To);
-  while (*FromI == *ToI) {
-    ++FromI;
-    ++ToI;
-  }
-
-  SmallString<128> Relative;
-  for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI)
-    sys::path::append(Relative, "..");
-
-  for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI)
-    sys::path::append(Relative, *ToI);
-
-#ifdef _WIN32
-  // Replace backslashes with slashes so that the path is portable between *nix
-  // and Windows.
-  std::replace(Relative.begin(), Relative.end(), '\\', '/');
-#endif
-
-  return Relative.str();
-}
-
 static bool is64BitKind(object::Archive::Kind Kind) {
   switch (Kind) {
   case object::Archive::K_GNU:
@@ -234,27 +203,11 @@ static bool is64BitKind(object::Archive::Kind Kind) {
   llvm_unreachable("not supported for writting");
 }
 
-static void addToStringTable(raw_ostream &Out, StringRef ArcName,
-                             const NewArchiveMember &M, bool Thin) {
-  StringRef ID = M.Buf->getBufferIdentifier();
-  if (Thin) {
-    if (M.IsNew)
-      Out << computeRelativePath(ArcName, ID);
-    else
-      Out << ID;
-  } else
-    Out << M.MemberName;
-  Out << "/\n";
-}
-
-static void printMemberHeader(raw_ostream &Out, uint64_t Pos,
-                              raw_ostream &StringTable,
-                              StringMap<uint64_t> &MemberNames,
-                              object::Archive::Kind Kind, bool Thin,
-                              StringRef ArcName, const NewArchiveMember &M,
-                              sys::TimePoint<std::chrono::seconds> ModTime,
-                              unsigned Size) {
-
+static void
+printMemberHeader(raw_ostream &Out, uint64_t Pos, raw_ostream &StringTable,
+                  StringMap<uint64_t> &MemberNames, object::Archive::Kind Kind,
+                  bool Thin, const NewArchiveMember &M,
+                  sys::TimePoint<std::chrono::seconds> ModTime, unsigned Size) {
   if (isBSDLike(Kind))
     return printBSDMemberHeader(Out, Pos, M.MemberName, ModTime, M.UID, M.GID,
                                 M.Perms, Size);
@@ -265,12 +218,12 @@ static void printMemberHeader(raw_ostream &Out, uint64_t Pos,
   uint64_t NamePos;
   if (Thin) {
     NamePos = StringTable.tell();
-    addToStringTable(StringTable, ArcName, M, Thin);
+    StringTable << M.MemberName << "/\n";
   } else {
     auto Insertion = MemberNames.insert({M.MemberName, uint64_t(0)});
     if (Insertion.second) {
       Insertion.first->second = StringTable.tell();
-      addToStringTable(StringTable, ArcName, M, Thin);
+      StringTable << M.MemberName << "/\n";
     }
     NamePos = Insertion.first->second;
   }
@@ -432,8 +385,8 @@ getSymbols(MemoryBufferRef Buf, raw_ostream &SymNames, bool &HasObject) {
 
 static Expected<std::vector<MemberData>>
 computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
-                  object::Archive::Kind Kind, bool Thin, StringRef ArcName,
-                  bool Deterministic, ArrayRef<NewArchiveMember> NewMembers) {
+                  object::Archive::Kind Kind, bool Thin, bool Deterministic,
+                  ArrayRef<NewArchiveMember> NewMembers) {
   static char PaddingData[8] = {'\n', '\n', '\n', '\n', '\n', '\n', '\n', '\n'};
 
   // This ignores the symbol table, but we only need the value mod 8 and the
@@ -520,8 +473,8 @@ computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
       ModTime = sys::toTimePoint(FilenameCount[M.MemberName]++);
     else
       ModTime = M.ModTime;
-    printMemberHeader(Out, Pos, StringTable, MemberNames, Kind, Thin, ArcName,
-                      M, ModTime, Buf.getBufferSize() + MemberPadding);
+    printMemberHeader(Out, Pos, StringTable, MemberNames, Kind, Thin, M,
+                      ModTime, Buf.getBufferSize() + MemberPadding);
     Out.flush();
 
     Expected<std::vector<unsigned>> Symbols =
@@ -540,11 +493,40 @@ computeMemberData(raw_ostream &StringTable, raw_ostream &SymNames,
   return Ret;
 }
 
-Error llvm::writeArchive(StringRef ArcName,
-                         ArrayRef<NewArchiveMember> NewMembers,
-                         bool WriteSymtab, object::Archive::Kind Kind,
-                         bool Deterministic, bool Thin,
-                         std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
+namespace llvm {
+// Compute the relative path from From to To.
+std::string computeArchiveRelativePath(StringRef From, StringRef To) {
+  if (sys::path::is_absolute(From) || sys::path::is_absolute(To))
+    return To;
+
+  StringRef DirFrom = sys::path::parent_path(From);
+  auto FromI = sys::path::begin(DirFrom);
+  auto ToI = sys::path::begin(To);
+  while (*FromI == *ToI) {
+    ++FromI;
+    ++ToI;
+  }
+
+  SmallString<128> Relative;
+  for (auto FromE = sys::path::end(DirFrom); FromI != FromE; ++FromI)
+    sys::path::append(Relative, "..");
+
+  for (auto ToE = sys::path::end(To); ToI != ToE; ++ToI)
+    sys::path::append(Relative, *ToI);
+
+#ifdef _WIN32
+  // Replace backslashes with slashes so that the path is portable between *nix
+  // and Windows.
+  std::replace(Relative.begin(), Relative.end(), '\\', '/');
+#endif
+
+  return Relative.str();
+}
+
+Error writeArchive(StringRef ArcName, ArrayRef<NewArchiveMember> NewMembers,
+                   bool WriteSymtab, object::Archive::Kind Kind,
+                   bool Deterministic, bool Thin,
+                   std::unique_ptr<MemoryBuffer> OldArchiveBuf) {
   assert((!Thin || !isBSDLike(Kind)) && "Only the gnu format has a thin mode");
 
   SmallString<0> SymNamesBuf;
@@ -553,7 +535,7 @@ Error llvm::writeArchive(StringRef ArcName,
   raw_svector_ostream StringTable(StringTableBuf);
 
   Expected<std::vector<MemberData>> DataOrErr = computeMemberData(
-      StringTable, SymNames, Kind, Thin, ArcName, Deterministic, NewMembers);
+      StringTable, SymNames, Kind, Thin, Deterministic, NewMembers);
   if (Error E = DataOrErr.takeError())
     return E;
   std::vector<MemberData> &Data = *DataOrErr;
@@ -630,3 +612,5 @@ Error llvm::writeArchive(StringRef ArcName,
 
   return Temp->keep(ArcName);
 }
+
+} // namespace llvm