Reapply r250906 with many suggested updates from Rafael Espindola.

The needed lld matching changes to be submitted immediately next,
but this revision will cause lld failures with this alone which is expected.

This removes the eating of the error in Archive::Child::getSize() when the characters
in the size field in the archive header for the member is not a number.  To do this we
have all of the needed methods return ErrorOr to push them up until we get out of lib.
Then the tools and can handle the error in whatever way is appropriate for that tool.

So the solution is to plumb all the ErrorOr stuff through everything that touches archives.
This include its iterators as one can create an Archive object but the first or any other
Child object may fail to be created due to a bad size field in its header.

Thanks to Lang Hames on the changes making child_iterator contain an
ErrorOr<Child> instead of a Child and the needed changes to ErrorOr.h to add
operator overloading for * and -> .

We don’t want to use llvm_unreachable() as it calls abort() and is produces a “crash”
and using report_fatal_error() to move the error checking will cause the program to
stop, neither of which are really correct in library code. There are still some uses of
these that should be cleaned up in this library code for other than the size field.

The test cases use archives with text files so one can see the non-digit character,
in this case a ‘%’, in the size field.

These changes will require corresponding changes to the lld project.  That will be
committed immediately after this change.  But this revision will cause lld failures
with this alone which is expected.

llvm-svn: 252192

1 files changed, 88 insertions, 46 deletions

diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 5ac91f23035..99b0650c8b7 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -46,7 +46,7 @@ StringRef ArchiveMemberHeader::getName() const {
 ErrorOr<uint32_t> ArchiveMemberHeader::getSize() const {
   uint32_t Ret;
   if (llvm::StringRef(Size, sizeof(Size)).rtrim(" ").getAsInteger(10, Ret))
-    return object_error::parse_failed;
+    return object_error::parse_failed; // Size is not a decimal number.
   return Ret;
 }
 
@@ -86,7 +86,8 @@ Archive::Child::Child(const Archive *Parent, StringRef Data,
                       uint16_t StartOfFile)
     : Parent(Parent), Data(Data), StartOfFile(StartOfFile) {}
 
-Archive::Child::Child(const Archive *Parent, const char *Start)
+Archive::Child::Child(const Archive *Parent, const char *Start,
+                      std::error_code *EC)
     : Parent(Parent) {
   if (!Start)
     return;
@@ -94,7 +95,10 @@ Archive::Child::Child(const Archive *Parent, const char *Start)
   uint64_t Size = sizeof(ArchiveMemberHeader);
   Data = StringRef(Start, Size);
   if (!isThinMember()) {
-    Size += getRawSize();
+    ErrorOr<uint64_t> MemberSize = getRawSize();
+    if ((*EC = MemberSize.getError()))
+      return;
+    Size += MemberSize.get();
     Data = StringRef(Start, Size);
   }
 
@@ -110,20 +114,20 @@ Archive::Child::Child(const Archive *Parent, const char *Start)
   }
 }
 
-uint64_t Archive::Child::getSize() const {
+ErrorOr<uint64_t> Archive::Child::getSize() const {
   if (Parent->IsThin) {
     ErrorOr<uint32_t> Size = getHeader()->getSize();
-    if (Size.getError())
-      return 0;
+    if (std::error_code EC = Size.getError())
+      return EC;
     return Size.get();
   }
   return Data.size() - StartOfFile;
 }
 
-uint64_t Archive::Child::getRawSize() const {
+ErrorOr<uint64_t> Archive::Child::getRawSize() const {
   ErrorOr<uint32_t> Size = getHeader()->getSize();
-  if (Size.getError())
-    return 0;
+  if (std::error_code EC = Size.getError())
+    return EC;
   return Size.get();
 }
 
@@ -133,8 +137,12 @@ bool Archive::Child::isThinMember() const {
 }
 
 ErrorOr<StringRef> Archive::Child::getBuffer() const {
-  if (!isThinMember())
-    return StringRef(Data.data() + StartOfFile, getSize());
+  if (!isThinMember()) {
+    ErrorOr<uint32_t> Size = getSize();
+    if (std::error_code EC = Size.getError())
+      return EC;
+    return StringRef(Data.data() + StartOfFile, Size.get());
+  }
   ErrorOr<StringRef> Name = getName();
   if (std::error_code EC = Name.getError())
     return EC;
@@ -148,7 +156,7 @@ ErrorOr<StringRef> Archive::Child::getBuffer() const {
   return Parent->ThinBuffers.back()->getBuffer();
 }
 
-Archive::Child Archive::Child::getNext() const {
+ErrorOr<Archive::Child> Archive::Child::getNext() const {
   size_t SpaceToSkip = Data.size();
   // If it's odd, add 1 to make it even.
   if (SpaceToSkip & 1)
@@ -156,11 +164,19 @@ Archive::Child Archive::Child::getNext() const {
 
   const char *NextLoc = Data.data() + SpaceToSkip;
 
+  // Check to see if this is at the end of the archive.
+  if (NextLoc == Parent->Data.getBufferEnd())
+    return Child(Parent, nullptr, nullptr);
+
   // Check to see if this is past the end of the archive.
-  if (NextLoc >= Parent->Data.getBufferEnd())
-    return Child(Parent, nullptr);
+  if (NextLoc > Parent->Data.getBufferEnd())
+    return object_error::parse_failed;
 
-  return Child(Parent, NextLoc);
+  std::error_code EC;
+  Child Ret(Parent, NextLoc, &EC);
+  if (EC)
+    return EC;
+  return Ret;
 }
 
 uint64_t Archive::Child::getChildOffset() const {
@@ -255,15 +271,26 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
   }
 
   // Get the special members.
-  child_iterator i = child_begin(false);
-  child_iterator e = child_end();
+  child_iterator I = child_begin(false);
+  if ((ec = I->getError()))
+    return;
+  child_iterator E = child_end();
 
-  if (i == e) {
+  if (I == E) {
     ec = std::error_code();
     return;
   }
+  const Child *C = &**I;
 
-  StringRef Name = i->getRawName();
+  auto Increment = [&]() {
+    ++I;
+    if ((ec = I->getError()))
+      return true;
+    C = &**I;
+    return false;
+  };
+
+  StringRef Name = C->getRawName();
 
   // Below is the pattern that is used to figure out the archive format
   // GNU archive format
@@ -288,9 +315,11 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
     Format = K_BSD;
     // We know that the symbol table is not an external file, so we just assert
     // there is no error.
-    SymbolTable = *i->getBuffer();
-    ++i;
-    setFirstRegular(*i);
+    SymbolTable = *C->getBuffer();
+    if (Increment())
+      return;
+    setFirstRegular(*C);
+
     ec = std::error_code();
     return;
   }
@@ -298,7 +327,7 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
   if (Name.startswith("#1/")) {
     Format = K_BSD;
     // We know this is BSD, so getName will work since there is no string table.
-    ErrorOr<StringRef> NameOrErr = i->getName();
+    ErrorOr<StringRef> NameOrErr = C->getName();
     ec = NameOrErr.getError();
     if (ec)
       return;
@@ -306,10 +335,11 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
     if (Name == "__.SYMDEF SORTED" || Name == "__.SYMDEF") {
       // We know that the symbol table is not an external file, so we just
       // assert there is no error.
-      SymbolTable = *i->getBuffer();
-      ++i;
+      SymbolTable = *C->getBuffer();
+      if (Increment())
+        return;
     }
-    setFirstRegular(*i);
+    setFirstRegular(*C);
     return;
   }
 
@@ -322,32 +352,34 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
   if (Name == "/" || Name == "/SYM64/") {
     // We know that the symbol table is not an external file, so we just assert
     // there is no error.
-    SymbolTable = *i->getBuffer();
+    SymbolTable = *C->getBuffer();
     if (Name == "/SYM64/")
       has64SymTable = true;
 
-    ++i;
-    if (i == e) {
+    if (Increment())
+      return;
+    if (I == E) {
       ec = std::error_code();
       return;
     }
-    Name = i->getRawName();
+    Name = C->getRawName();
   }
 
   if (Name == "//") {
     Format = has64SymTable ? K_MIPS64 : K_GNU;
     // The string table is never an external member, so we just assert on the
     // ErrorOr.
-    StringTable = *i->getBuffer();
-    ++i;
-    setFirstRegular(*i);
+    StringTable = *C->getBuffer();
+    if (Increment())
+      return;
+    setFirstRegular(*C);
     ec = std::error_code();
     return;
   }
 
   if (Name[0] != '/') {
     Format = has64SymTable ? K_MIPS64 : K_GNU;
-    setFirstRegular(*i);
+    setFirstRegular(*C);
     ec = std::error_code();
     return;
   }
@@ -360,25 +392,28 @@ Archive::Archive(MemoryBufferRef Source, std::error_code &ec)
   Format = K_COFF;
   // We know that the symbol table is not an external file, so we just assert
   // there is no error.
-  SymbolTable = *i->getBuffer();
+  SymbolTable = *C->getBuffer();
+
+  if (Increment())
+    return;
 
-  ++i;
-  if (i == e) {
-    setFirstRegular(*i);
+  if (I == E) {
+    setFirstRegular(*C);
     ec = std::error_code();
     return;
   }
 
-  Name = i->getRawName();
+  Name = C->getRawName();
 
   if (Name == "//") {
     // The string table is never an external member, so we just assert on the
     // ErrorOr.
-    StringTable = *i->getBuffer();
-    ++i;
+    StringTable = *C->getBuffer();
+    if (Increment())
+      return;
   }
 
-  setFirstRegular(*i);
+  setFirstRegular(*C);
   ec = std::error_code();
 }
 
@@ -390,12 +425,15 @@ Archive::child_iterator Archive::child_begin(bool SkipInternal) const {
     return Child(this, FirstRegularData, FirstRegularStartOfFile);
 
   const char *Loc = Data.getBufferStart() + strlen(Magic);
-  Child c(this, Loc);
-  return c;
+  std::error_code EC;
+  Child c(this, Loc, &EC);
+  if (EC)
+    return child_iterator(EC);
+  return child_iterator(c);
 }
 
 Archive::child_iterator Archive::child_end() const {
-  return Child(this, nullptr);
+  return Child(this, nullptr, nullptr);
 }
 
 StringRef Archive::Symbol::getName() const {
@@ -447,7 +485,11 @@ ErrorOr<Archive::Child> Archive::Symbol::getMember() const {
   }
 
   const char *Loc = Parent->getData().begin() + Offset;
-  return Child(Parent, Loc);
+  std::error_code EC;
+  Child C(Parent, Loc, &EC);
+  if (EC)
+    return EC;
+  return C;
 }
 
 Archive::Symbol Archive::Symbol::getNext() const {