lib/Object/Archive.cpp - platform/external/llvm - Git at Google

 //===- Archive.cpp - ar File Format implementation --------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file defines the ArchiveObjectFile class.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Object/Archive.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/Support/Endian.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/MemoryBuffer.h"

 using namespace llvm;
 using namespace object;

 static const char *Magic = "!<arch>\n";

 namespace {
 struct ArchiveMemberHeader {
   char Name[16];
   char LastModified[12];
   char UID[6];
   char GID[6];
   char AccessMode[8];
   char Size[10]; ///< Size of data, not including header or padding.
   char Terminator[2];

   ///! Get the name without looking up long names.
   StringRef getName() const {
     char EndCond;
     if (Name[0] == '/' || Name[0] == '#')
       EndCond = ' ';
     else
       EndCond = '/';
     StringRef::size_type end = StringRef(Name, sizeof(Name)).find(EndCond);
     if (end == StringRef::npos)
       end = sizeof(Name);
     assert(end <= sizeof(Name) && end > 0);
     // Don't include the EndCond if there is one.
     return StringRef(Name, end);
   }

   uint64_t getSize() const {
     APInt ret;
     StringRef(Size, sizeof(Size)).getAsInteger(10, ret);
     return ret.getZExtValue();
   }
 };
 }

 static const ArchiveMemberHeader *ToHeader(const char *base) {
   return reinterpret_cast<const ArchiveMemberHeader *>(base);
 }


 static bool isInternalMember(const ArchiveMemberHeader &amh) {
   static const char *const internals[] = {
     "/",
     "//",
     "#_LLVM_SYM_TAB_#"
   };

   StringRef name = amh.getName();
   for (std::size_t i = 0; i < sizeof(internals) / sizeof(*internals); ++i) {
     if (name == internals[i])
       return true;
   }
   return false;
 }

 void Archive::anchor() { }

 Archive::Child Archive::Child::getNext() const {
   size_t SpaceToSkip = sizeof(ArchiveMemberHeader) +
     ToHeader(Data.data())->getSize();
   // If it's odd, add 1 to make it even.
   if (SpaceToSkip & 1)
     ++SpaceToSkip;

   const char *NextLoc = Data.data() + SpaceToSkip;

   // Check to see if this is past the end of the archive.
   if (NextLoc >= Parent->Data->getBufferEnd())
     return Child(Parent, StringRef(0, 0));

   size_t NextSize = sizeof(ArchiveMemberHeader) +
     ToHeader(NextLoc)->getSize();

   return Child(Parent, StringRef(NextLoc, NextSize));
 }

 error_code Archive::Child::getName(StringRef &Result) const {
   StringRef name = ToHeader(Data.data())->getName();
   // Check if it's a special name.
   if (name[0] == '/') {
     if (name.size() == 1) { // Linker member.
       Result = name;
       return object_error::success;
     }
     if (name.size() == 2 && name[1] == '/') { // String table.
       Result = name;
       return object_error::success;
     }
     // It's a long name.
     // Get the offset.
     APInt offset;
     name.substr(1).getAsInteger(10, offset);
     const char *addr = Parent->StringTable->Data.begin()
                        + sizeof(ArchiveMemberHeader)
                        + offset.getZExtValue();
     // Verify it.
     if (Parent->StringTable == Parent->end_children()
         || addr < (Parent->StringTable->Data.begin()
                    + sizeof(ArchiveMemberHeader))
         || addr > (Parent->StringTable->Data.begin()
                    + sizeof(ArchiveMemberHeader)
                    + Parent->StringTable->getSize()))
       return object_error::parse_failed;

     // GNU long file names end with a /.
     if (Parent->kind() == K_GNU) {
       StringRef::size_type End = StringRef(addr).find('/');
       Result = StringRef(addr, End);
     } else {
       Result = addr;
     }
     return object_error::success;
   } else if (name.startswith("#1/")) {
     APInt name_size;
     name.substr(3).getAsInteger(10, name_size);
     Result = Data.substr(0, name_size.getZExtValue());
     return object_error::success;
   }
   // It's a simple name.
   if (name[name.size() - 1] == '/')
     Result = name.substr(0, name.size() - 1);
   else
     Result = name;
   return object_error::success;
 }

 uint64_t Archive::Child::getSize() const {
   uint64_t size = ToHeader(Data.data())->getSize();
   // Don't include attached name.
   StringRef name =  ToHeader(Data.data())->getName();
   if (name.startswith("#1/")) {
     APInt name_size;
     name.substr(3).getAsInteger(10, name_size);
     size -= name_size.getZExtValue();
   }
   return size;
 }

 MemoryBuffer *Archive::Child::getBuffer() const {
   StringRef name;
   if (getName(name)) return NULL;
   int size = sizeof(ArchiveMemberHeader);
   if (name.startswith("#1/")) {
     APInt name_size;
     name.substr(3).getAsInteger(10, name_size);
     size += name_size.getZExtValue();
   }
   return MemoryBuffer::getMemBuffer(Data.substr(size, getSize()),
                                     name,
                                     false);
 }

 error_code Archive::Child::getAsBinary(OwningPtr<Binary> &Result) const {
   OwningPtr<Binary> ret;
   if (error_code ec =
     createBinary(getBuffer(), ret))
     return ec;
   Result.swap(ret);
   return object_error::success;
 }

 Archive::Archive(MemoryBuffer *source, error_code &ec)
   : Binary(Binary::ID_Archive, source) {
   // Check for sufficient magic.
   if (!source || source->getBufferSize()
                  < (8 + sizeof(ArchiveMemberHeader) + 2) // Smallest archive.
               || StringRef(source->getBufferStart(), 8) != Magic) {
     ec = object_error::invalid_file_type;
     return;
   }

   // Get the special members.
   child_iterator i = begin_children(false);
   child_iterator e = end_children();

   StringRef name;
   if ((ec = i->getName(name)))
     return;

   // Below is the pattern that is used to figure out the archive format
   // GNU archive format
   //  First member : / (points to the symbol table )
   //  Second member : // (may exist, if it exists, points to the string table)
   //  Note : The string table is used if the filename exceeds 15 characters
   // BSD archive format
   //  First member : __.SYMDEF (points to the symbol table)
   //  There is no string table, if the filename exceeds 15 characters or has a
   //  embedded space, the filename has #1/<size>, The size represents the size
   //  of the filename that needs to be read after the archive header
   // COFF archive format
   //  First member : /
   //  Second member : / (provides a directory of symbols)
   //  Third member : // contains the string table, this is present even if the
   //                    string table is empty
   if (name == "/") {
     SymbolTable = i;
     StringTable = e;
     if (i != e) ++i;
     if ((ec = i->getName(name)))
       return;
     if (name[0] != '/') {
       Format = K_GNU;
     } else if ((name.size() > 1) && (name == "//")) {
       Format = K_GNU;
       StringTable = i;
       ++i;
     } else  {
       Format = K_COFF;
       if (i != e) {
         SymbolTable = i;
         ++i;
       }
       if (i != e) {
         StringTable = i;
       }
     }
   } else if (name == "__.SYMDEF") {
     Format = K_BSD;
     SymbolTable = i;
     StringTable = e;
   }
   ec = object_error::success;
 }

 Archive::child_iterator Archive::begin_children(bool skip_internal) const {
   const char *Loc = Data->getBufferStart() + strlen(Magic);
   size_t Size = sizeof(ArchiveMemberHeader) +
     ToHeader(Loc)->getSize();
   Child c(this, StringRef(Loc, Size));
   // Skip internals at the beginning of an archive.
   if (skip_internal && isInternalMember(*ToHeader(Loc)))
     return c.getNext();
   return c;
 }

 Archive::child_iterator Archive::end_children() const {
   return Child(this, StringRef(0, 0));
 }

 error_code Archive::Symbol::getName(StringRef &Result) const {
   Result =
     StringRef(Parent->SymbolTable->getBuffer()->getBufferStart() + StringIndex);
   return object_error::success;
 }

 error_code Archive::Symbol::getMember(child_iterator &Result) const {
   const char *Buf = Parent->SymbolTable->getBuffer()->getBufferStart();
   const char *Offsets = Buf + 4;
   uint32_t Offset = 0;
   if (Parent->kind() == K_GNU) {
     Offset = *(reinterpret_cast<const support::ubig32_t*>(Offsets)
                + SymbolIndex);
   } else if (Parent->kind() == K_BSD) {
     llvm_unreachable("BSD format is not supported");
   } else {
     uint32_t MemberCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);

     // Skip offsets.
     Buf += sizeof(support::ulittle32_t)
            + (MemberCount * sizeof(support::ulittle32_t));

     uint32_t SymbolCount = *reinterpret_cast<const support::ulittle32_t*>(Buf);

     if (SymbolIndex >= SymbolCount)
       return object_error::parse_failed;

     // Skip SymbolCount to get to the indices table.
     const char *Indices = Buf + sizeof(support::ulittle32_t);

     // Get the index of the offset in the file member offset table for this
     // symbol.
     uint16_t OffsetIndex =
       *(reinterpret_cast<const support::ulittle16_t*>(Indices)
         + SymbolIndex);
     // Subtract 1 since OffsetIndex is 1 based.
     --OffsetIndex;

     if (OffsetIndex >= MemberCount)
       return object_error::parse_failed;

     Offset = *(reinterpret_cast<const support::ulittle32_t*>(Offsets)
                + OffsetIndex);
   }

   const char *Loc = Parent->getData().begin() + Offset;
   size_t Size = sizeof(ArchiveMemberHeader) +
     ToHeader(Loc)->getSize();
   Result = Child(Parent, StringRef(Loc, Size));

   return object_error::success;
 }

 Archive::Symbol Archive::Symbol::getNext() const {
   Symbol t(*this);
   // Go to one past next null.
   t.StringIndex =
     Parent->SymbolTable->getBuffer()->getBuffer().find('\0', t.StringIndex) + 1;
   ++t.SymbolIndex;
   return t;
 }

 Archive::symbol_iterator Archive::begin_symbols() const {
   const char *buf = SymbolTable->getBuffer()->getBufferStart();
   if (kind() == K_GNU) {
     uint32_t symbol_count = 0;
     symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
     buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
   } else if (kind() == K_BSD) {
     llvm_unreachable("BSD archive format is not supported");
   } else {
     uint32_t member_count = 0;
     uint32_t symbol_count = 0;
     member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
     buf += 4 + (member_count * 4); // Skip offsets.
     symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
     buf += 4 + (symbol_count * 2); // Skip indices.
   }
   uint32_t string_start_offset =
     buf - SymbolTable->getBuffer()->getBufferStart();
   return symbol_iterator(Symbol(this, 0, string_start_offset));
 }

 Archive::symbol_iterator Archive::end_symbols() const {
   const char *buf = SymbolTable->getBuffer()->getBufferStart();
   uint32_t symbol_count = 0;
   if (kind() == K_GNU) {
     symbol_count = *reinterpret_cast<const support::ubig32_t*>(buf);
     buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
   } else if (kind() == K_BSD) {
     llvm_unreachable("BSD archive format is not supported");
   } else {
     uint32_t member_count = 0;
     member_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
     buf += 4 + (member_count * 4); // Skip offsets.
     symbol_count = *reinterpret_cast<const support::ulittle32_t*>(buf);
   }
   return symbol_iterator(
     Symbol(this, symbol_count, 0));
 }

 Archive::child_iterator Archive::findSym(StringRef name) const {
   Archive::symbol_iterator bs = begin_symbols();
   Archive::symbol_iterator es = end_symbols();
   Archive::child_iterator result;

   StringRef symname;
   for (; bs != es; ++bs) {
     if (bs->getName(symname))
         return end_children();
     if (symname == name) {
       if (bs->getMember(result))
         return end_children();
       return result;
     }
   }
   return end_children();
 }
	//===- Archive.cpp - ar File Format implementation --------------- C++ --===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file defines the ArchiveObjectFile class.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Object/Archive.h"
	#include "llvm/ADT/APInt.h"
	#include "llvm/Support/Endian.h"
	#include "llvm/Support/ErrorHandling.h"
	#include "llvm/Support/MemoryBuffer.h"

	using namespace llvm;
	using namespace object;

	static const char *Magic = "!<arch>\n";

	namespace {
	struct ArchiveMemberHeader {
	char Name[16];
	char LastModified[12];
	char UID[6];
	char GID[6];
	char AccessMode[8];
	char Size[10]; ///< Size of data, not including header or padding.
	char Terminator[2];

	///! Get the name without looking up long names.
	StringRef getName() const {
	char EndCond;
	if (Name[0] == '/' \|\| Name[0] == '#')
	EndCond = ' ';
	else
	EndCond = '/';
	StringRef::size_type end = StringRef(Name, sizeof(Name)).find(EndCond);
	if (end == StringRef::npos)
	end = sizeof(Name);
	assert(end <= sizeof(Name) && end > 0);
	// Don't include the EndCond if there is one.
	return StringRef(Name, end);
	}

	uint64_t getSize() const {
	APInt ret;
	StringRef(Size, sizeof(Size)).getAsInteger(10, ret);
	return ret.getZExtValue();
	}
	};
	}

	static const ArchiveMemberHeader ToHeader(const char base) {
	return reinterpret_cast<const ArchiveMemberHeader *>(base);
	}


	static bool isInternalMember(const ArchiveMemberHeader &amh) {
	static const char *const internals[] = {
	"/",
	"//",
	"#_LLVM_SYM_TAB_#"
	};

	StringRef name = amh.getName();
	for (std::size_t i = 0; i < sizeof(internals) / sizeof(*internals); ++i) {
	if (name == internals[i])
	return true;
	}
	return false;
	}

	void Archive::anchor() { }

	Archive::Child Archive::Child::getNext() const {
	size_t SpaceToSkip = sizeof(ArchiveMemberHeader) +
	ToHeader(Data.data())->getSize();
	// If it's odd, add 1 to make it even.
	if (SpaceToSkip & 1)
	++SpaceToSkip;

	const char *NextLoc = Data.data() + SpaceToSkip;

	// Check to see if this is past the end of the archive.
	if (NextLoc >= Parent->Data->getBufferEnd())
	return Child(Parent, StringRef(0, 0));

	size_t NextSize = sizeof(ArchiveMemberHeader) +
	ToHeader(NextLoc)->getSize();

	return Child(Parent, StringRef(NextLoc, NextSize));
	}

	error_code Archive::Child::getName(StringRef &Result) const {
	StringRef name = ToHeader(Data.data())->getName();
	// Check if it's a special name.
	if (name[0] == '/') {
	if (name.size() == 1) { // Linker member.
	Result = name;
	return object_error::success;
	}
	if (name.size() == 2 && name[1] == '/') { // String table.
	Result = name;
	return object_error::success;
	}
	// It's a long name.
	// Get the offset.
	APInt offset;
	name.substr(1).getAsInteger(10, offset);
	const char *addr = Parent->StringTable->Data.begin()
	+ sizeof(ArchiveMemberHeader)
	+ offset.getZExtValue();
	// Verify it.
	if (Parent->StringTable == Parent->end_children()
	\|\| addr < (Parent->StringTable->Data.begin()
	+ sizeof(ArchiveMemberHeader))
	\|\| addr > (Parent->StringTable->Data.begin()
	+ sizeof(ArchiveMemberHeader)
	+ Parent->StringTable->getSize()))
	return object_error::parse_failed;

	// GNU long file names end with a /.
	if (Parent->kind() == K_GNU) {
	StringRef::size_type End = StringRef(addr).find('/');
	Result = StringRef(addr, End);
	} else {
	Result = addr;
	}
	return object_error::success;
	} else if (name.startswith("#1/")) {
	APInt name_size;
	name.substr(3).getAsInteger(10, name_size);
	Result = Data.substr(0, name_size.getZExtValue());
	return object_error::success;
	}
	// It's a simple name.
	if (name[name.size() - 1] == '/')
	Result = name.substr(0, name.size() - 1);
	else
	Result = name;
	return object_error::success;
	}

	uint64_t Archive::Child::getSize() const {
	uint64_t size = ToHeader(Data.data())->getSize();
	// Don't include attached name.
	StringRef name = ToHeader(Data.data())->getName();
	if (name.startswith("#1/")) {
	APInt name_size;
	name.substr(3).getAsInteger(10, name_size);
	size -= name_size.getZExtValue();
	}
	return size;
	}

	MemoryBuffer *Archive::Child::getBuffer() const {
	StringRef name;
	if (getName(name)) return NULL;
	int size = sizeof(ArchiveMemberHeader);
	if (name.startswith("#1/")) {
	APInt name_size;
	name.substr(3).getAsInteger(10, name_size);
	size += name_size.getZExtValue();
	}
	return MemoryBuffer::getMemBuffer(Data.substr(size, getSize()),
	name,
	false);
	}

	error_code Archive::Child::getAsBinary(OwningPtr<Binary> &Result) const {
	OwningPtr<Binary> ret;
	if (error_code ec =
	createBinary(getBuffer(), ret))
	return ec;
	Result.swap(ret);
	return object_error::success;
	}

	Archive::Archive(MemoryBuffer *source, error_code &ec)
	: Binary(Binary::ID_Archive, source) {
	// Check for sufficient magic.
	if (!source \|\| source->getBufferSize()
	< (8 + sizeof(ArchiveMemberHeader) + 2) // Smallest archive.
	\|\| StringRef(source->getBufferStart(), 8) != Magic) {
	ec = object_error::invalid_file_type;
	return;
	}

	// Get the special members.
	child_iterator i = begin_children(false);
	child_iterator e = end_children();

	StringRef name;
	if ((ec = i->getName(name)))
	return;

	// Below is the pattern that is used to figure out the archive format
	// GNU archive format
	// First member : / (points to the symbol table )
	// Second member : // (may exist, if it exists, points to the string table)
	// Note : The string table is used if the filename exceeds 15 characters
	// BSD archive format
	// First member : __.SYMDEF (points to the symbol table)
	// There is no string table, if the filename exceeds 15 characters or has a
	// embedded space, the filename has #1/<size>, The size represents the size
	// of the filename that needs to be read after the archive header
	// COFF archive format
	// First member : /
	// Second member : / (provides a directory of symbols)
	// Third member : // contains the string table, this is present even if the
	// string table is empty
	if (name == "/") {
	SymbolTable = i;
	StringTable = e;
	if (i != e) ++i;
	if ((ec = i->getName(name)))
	return;
	if (name[0] != '/') {
	Format = K_GNU;
	} else if ((name.size() > 1) && (name == "//")) {
	Format = K_GNU;
	StringTable = i;
	++i;
	} else {
	Format = K_COFF;
	if (i != e) {
	SymbolTable = i;
	++i;
	}
	if (i != e) {
	StringTable = i;
	}
	}
	} else if (name == "__.SYMDEF") {
	Format = K_BSD;
	SymbolTable = i;
	StringTable = e;
	}
	ec = object_error::success;
	}

	Archive::child_iterator Archive::begin_children(bool skip_internal) const {
	const char *Loc = Data->getBufferStart() + strlen(Magic);
	size_t Size = sizeof(ArchiveMemberHeader) +
	ToHeader(Loc)->getSize();
	Child c(this, StringRef(Loc, Size));
	// Skip internals at the beginning of an archive.
	if (skip_internal && isInternalMember(*ToHeader(Loc)))
	return c.getNext();
	return c;
	}

	Archive::child_iterator Archive::end_children() const {
	return Child(this, StringRef(0, 0));
	}

	error_code Archive::Symbol::getName(StringRef &Result) const {
	Result =
	StringRef(Parent->SymbolTable->getBuffer()->getBufferStart() + StringIndex);
	return object_error::success;
	}

	error_code Archive::Symbol::getMember(child_iterator &Result) const {
	const char *Buf = Parent->SymbolTable->getBuffer()->getBufferStart();
	const char *Offsets = Buf + 4;
	uint32_t Offset = 0;
	if (Parent->kind() == K_GNU) {
	Offset = (reinterpret_cast<const support::ubig32_t>(Offsets)
	+ SymbolIndex);
	} else if (Parent->kind() == K_BSD) {
	llvm_unreachable("BSD format is not supported");
	} else {
	uint32_t MemberCount = reinterpret_cast<const support::ulittle32_t>(Buf);

	// Skip offsets.
	Buf += sizeof(support::ulittle32_t)
	+ (MemberCount * sizeof(support::ulittle32_t));

	uint32_t SymbolCount = reinterpret_cast<const support::ulittle32_t>(Buf);

	if (SymbolIndex >= SymbolCount)
	return object_error::parse_failed;

	// Skip SymbolCount to get to the indices table.
	const char *Indices = Buf + sizeof(support::ulittle32_t);

	// Get the index of the offset in the file member offset table for this
	// symbol.
	uint16_t OffsetIndex =
	(reinterpret_cast<const support::ulittle16_t>(Indices)
	+ SymbolIndex);
	// Subtract 1 since OffsetIndex is 1 based.
	--OffsetIndex;

	if (OffsetIndex >= MemberCount)
	return object_error::parse_failed;

	Offset = (reinterpret_cast<const support::ulittle32_t>(Offsets)
	+ OffsetIndex);
	}

	const char *Loc = Parent->getData().begin() + Offset;
	size_t Size = sizeof(ArchiveMemberHeader) +
	ToHeader(Loc)->getSize();
	Result = Child(Parent, StringRef(Loc, Size));

	return object_error::success;
	}

	Archive::Symbol Archive::Symbol::getNext() const {
	Symbol t(*this);
	// Go to one past next null.
	t.StringIndex =
	Parent->SymbolTable->getBuffer()->getBuffer().find('\0', t.StringIndex) + 1;
	++t.SymbolIndex;
	return t;
	}

	Archive::symbol_iterator Archive::begin_symbols() const {
	const char *buf = SymbolTable->getBuffer()->getBufferStart();
	if (kind() == K_GNU) {
	uint32_t symbol_count = 0;
	symbol_count = reinterpret_cast<const support::ubig32_t>(buf);
	buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
	} else if (kind() == K_BSD) {
	llvm_unreachable("BSD archive format is not supported");
	} else {
	uint32_t member_count = 0;
	uint32_t symbol_count = 0;
	member_count = reinterpret_cast<const support::ulittle32_t>(buf);
	buf += 4 + (member_count * 4); // Skip offsets.
	symbol_count = reinterpret_cast<const support::ulittle32_t>(buf);
	buf += 4 + (symbol_count * 2); // Skip indices.
	}
	uint32_t string_start_offset =
	buf - SymbolTable->getBuffer()->getBufferStart();
	return symbol_iterator(Symbol(this, 0, string_start_offset));
	}

	Archive::symbol_iterator Archive::end_symbols() const {
	const char *buf = SymbolTable->getBuffer()->getBufferStart();
	uint32_t symbol_count = 0;
	if (kind() == K_GNU) {
	symbol_count = reinterpret_cast<const support::ubig32_t>(buf);
	buf += sizeof(uint32_t) + (symbol_count * (sizeof(uint32_t)));
	} else if (kind() == K_BSD) {
	llvm_unreachable("BSD archive format is not supported");
	} else {
	uint32_t member_count = 0;
	member_count = reinterpret_cast<const support::ulittle32_t>(buf);
	buf += 4 + (member_count * 4); // Skip offsets.
	symbol_count = reinterpret_cast<const support::ulittle32_t>(buf);
	}
	return symbol_iterator(
	Symbol(this, symbol_count, 0));
	}

	Archive::child_iterator Archive::findSym(StringRef name) const {
	Archive::symbol_iterator bs = begin_symbols();
	Archive::symbol_iterator es = end_symbols();
	Archive::child_iterator result;

	StringRef symname;
	for (; bs != es; ++bs) {
	if (bs->getName(symname))
	return end_children();
	if (symname == name) {
	if (bs->getMember(result))
	return end_children();
	return result;
	}
	}
	return end_children();
	}