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llvm-project/llvm/lib/Object/Archive.cpp

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//===- 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/ErrorHandling.h"
#include "llvm/Support/Endian.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();
}
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