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

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//===-- ArchiveReader.cpp - Read LLVM archive files -------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Builds up standard unix archive files (.a) containing LLVM bitcode.
//
//===----------------------------------------------------------------------===//
#include "ArchiveInternals.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Module.h"
#include <cstdlib>
#include <memory>
using namespace llvm;
/// Read a variable-bit-rate encoded unsigned integer
static inline unsigned readInteger(const char*&At, const char*End) {
unsigned Shift = 0;
unsigned Result = 0;
do {
if (At == End)
return Result;
Result |= (unsigned)((*At++) & 0x7F) << Shift;
Shift += 7;
} while (At[-1] & 0x80);
return Result;
}
// Completely parse the Archive's symbol table and populate symTab member var.
bool
Archive::parseSymbolTable(const void* data, unsigned size, std::string* error) {
const char* At = (const char*) data;
const char* End = At + size;
while (At < End) {
unsigned offset = readInteger(At, End);
if (At == End) {
if (error)
*error = "Ran out of data reading vbr_uint for symtab offset!";
return false;
}
unsigned length = readInteger(At, End);
if (At == End) {
if (error)
*error = "Ran out of data reading vbr_uint for symtab length!";
return false;
}
if (At + length > End) {
if (error)
*error = "Malformed symbol table: length not consistent with size";
return false;
}
// we don't care if it can't be inserted (duplicate entry)
symTab.insert(std::make_pair(std::string(At, length), offset));
At += length;
}
symTabSize = size;
return true;
}
// This member parses an ArchiveMemberHeader that is presumed to be pointed to
// by At. The At pointer is updated to the byte just after the header, which
// can be variable in size.
ArchiveMember*
Archive::parseMemberHeader(const char*& At, const char* End, std::string* error)
{
if (At + sizeof(ArchiveMemberHeader) >= End) {
if (error)
*error = "Unexpected end of file";
return 0;
}
// Cast archive member header
ArchiveMemberHeader* Hdr = (ArchiveMemberHeader*)At;
At += sizeof(ArchiveMemberHeader);
// Extract the size and determine if the file is
// compressed or not (negative length).
int flags = 0;
int MemberSize = atoi(Hdr->size);
if (MemberSize < 0) {
flags |= ArchiveMember::CompressedFlag;
MemberSize = -MemberSize;
}
// Check the size of the member for sanity
if (At + MemberSize > End) {
if (error)
*error = "invalid member length in archive file";
return 0;
}
// Check the member signature
if (!Hdr->checkSignature()) {
if (error)
*error = "invalid file member signature";
return 0;
}
// Convert and check the member name
// The empty name ( '/' and 15 blanks) is for a foreign (non-LLVM) symbol
// table. The special name "//" and 14 blanks is for a string table, used
// for long file names. This library doesn't generate either of those but
// it will accept them. If the name starts with #1/ and the remainder is
// digits, then those digits specify the length of the name that is
// stored immediately following the header. The special name
// __LLVM_SYM_TAB__ identifies the symbol table for LLVM bitcode.
// Anything else is a regular, short filename that is terminated with
// a '/' and blanks.
std::string pathname;
switch (Hdr->name[0]) {
case '#':
if (Hdr->name[1] == '1' && Hdr->name[2] == '/') {
if (isdigit(Hdr->name[3])) {
unsigned len = atoi(&Hdr->name[3]);
const char *nulp = (const char *)memchr(At, '\0', len);
pathname.assign(At, nulp != 0 ? nulp - At : len);
At += len;
MemberSize -= len;
flags |= ArchiveMember::HasLongFilenameFlag;
} else {
if (error)
*error = "invalid long filename";
return 0;
}
} else if (Hdr->name[1] == '_' &&
(0 == memcmp(Hdr->name, ARFILE_LLVM_SYMTAB_NAME, 16))) {
// The member is using a long file name (>15 chars) format.
// This format is standard for 4.4BSD and Mac OSX operating
// systems. LLVM uses it similarly. In this format, the
// remainder of the name field (after #1/) specifies the
// length of the file name which occupy the first bytes of
// the member's data. The pathname already has the #1/ stripped.
pathname.assign(ARFILE_LLVM_SYMTAB_NAME);
flags |= ArchiveMember::LLVMSymbolTableFlag;
}
break;
case '/':
if (Hdr->name[1]== '/') {
if (0 == memcmp(Hdr->name, ARFILE_STRTAB_NAME, 16)) {
pathname.assign(ARFILE_STRTAB_NAME);
flags |= ArchiveMember::StringTableFlag;
} else {
if (error)
*error = "invalid string table name";
return 0;
}
} else if (Hdr->name[1] == ' ') {
if (0 == memcmp(Hdr->name, ARFILE_SVR4_SYMTAB_NAME, 16)) {
pathname.assign(ARFILE_SVR4_SYMTAB_NAME);
flags |= ArchiveMember::SVR4SymbolTableFlag;
} else {
if (error)
*error = "invalid SVR4 symbol table name";
return 0;
}
} else if (isdigit(Hdr->name[1])) {
unsigned index = atoi(&Hdr->name[1]);
if (index < strtab.length()) {
const char* namep = strtab.c_str() + index;
const char* endp = strtab.c_str() + strtab.length();
const char* p = namep;
const char* last_p = p;
while (p < endp) {
if (*p == '\n' && *last_p == '/') {
pathname.assign(namep, last_p - namep);
flags |= ArchiveMember::HasLongFilenameFlag;
break;
}
last_p = p;
p++;
}
if (p >= endp) {
if (error)
*error = "missing name termiantor in string table";
return 0;
}
} else {
if (error)
*error = "name index beyond string table";
return 0;
}
}
break;
case '_':
if (Hdr->name[1] == '_' &&
(0 == memcmp(Hdr->name, ARFILE_BSD4_SYMTAB_NAME, 16))) {
pathname.assign(ARFILE_BSD4_SYMTAB_NAME);
flags |= ArchiveMember::BSD4SymbolTableFlag;
break;
}
/* FALL THROUGH */
default:
char* slash = (char*) memchr(Hdr->name, '/', 16);
if (slash == 0)
slash = Hdr->name + 16;
pathname.assign(Hdr->name, slash - Hdr->name);
break;
}
// Determine if this is a bitcode file
switch (sys::IdentifyFileType(At, 4)) {
case sys::Bitcode_FileType:
flags |= ArchiveMember::BitcodeFlag;
break;
default:
flags &= ~ArchiveMember::BitcodeFlag;
break;
}
// Instantiate the ArchiveMember to be filled
ArchiveMember* member = new ArchiveMember(this);
// Fill in fields of the ArchiveMember
member->parent = this;
member->path.set(pathname);
member->info.fileSize = MemberSize;
member->info.modTime.fromEpochTime(atoi(Hdr->date));
unsigned int mode;
sscanf(Hdr->mode, "%o", &mode);
member->info.mode = mode;
member->info.user = atoi(Hdr->uid);
member->info.group = atoi(Hdr->gid);
member->flags = flags;
member->data = At;
return member;
}
bool
Archive::checkSignature(std::string* error) {
// Check the magic string at file's header
if (mapfile->getBufferSize() < 8 || memcmp(base, ARFILE_MAGIC, 8)) {
if (error)
*error = "invalid signature for an archive file";
return false;
}
return true;
}
// This function loads the entire archive and fully populates its ilist with
// the members of the archive file. This is typically used in preparation for
// editing the contents of the archive.
bool
Archive::loadArchive(std::string* error) {
// Set up parsing
members.clear();
symTab.clear();
const char *At = base;
const char *End = mapfile->getBufferEnd();
if (!checkSignature(error))
return false;
At += 8; // Skip the magic string.
bool seenSymbolTable = false;
bool foundFirstFile = false;
while (At < End) {
// parse the member header
const char* Save = At;
ArchiveMember* mbr = parseMemberHeader(At, End, error);
if (!mbr)
return false;
// check if this is the foreign symbol table
if (mbr->isSVR4SymbolTable() || mbr->isBSD4SymbolTable()) {
// We just save this but don't do anything special
// with it. It doesn't count as the "first file".
if (foreignST) {
// What? Multiple foreign symbol tables? Just chuck it
// and retain the last one found.
delete foreignST;
}
foreignST = mbr;
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
} else if (mbr->isStringTable()) {
// Simply suck the entire string table into a string
// variable. This will be used to get the names of the
// members that use the "/ddd" format for their names
// (SVR4 style long names).
strtab.assign(At, mbr->getSize());
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
delete mbr;
} else if (mbr->isLLVMSymbolTable()) {
// This is the LLVM symbol table for the archive. If we've seen it
// already, its an error. Otherwise, parse the symbol table and move on.
if (seenSymbolTable) {
if (error)
*error = "invalid archive: multiple symbol tables";
return false;
}
if (!parseSymbolTable(mbr->getData(), mbr->getSize(), error))
return false;
seenSymbolTable = true;
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
delete mbr; // We don't need this member in the list of members.
} else {
// This is just a regular file. If its the first one, save its offset.
// Otherwise just push it on the list and move on to the next file.
if (!foundFirstFile) {
firstFileOffset = Save - base;
foundFirstFile = true;
}
members.push_back(mbr);
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
}
}
return true;
}
// Open and completely load the archive file.
Archive*
Archive::OpenAndLoad(const sys::Path& file, LLVMContext& C,
std::string* ErrorMessage) {
std::auto_ptr<Archive> result ( new Archive(file, C));
if (result->mapToMemory(ErrorMessage))
return 0;
if (!result->loadArchive(ErrorMessage))
return 0;
return result.release();
}
// Get all the bitcode modules from the archive
bool
Archive::getAllModules(std::vector<Module*>& Modules,
std::string* ErrMessage) {
for (iterator I=begin(), E=end(); I != E; ++I) {
if (I->isBitcode()) {
std::string FullMemberName = archPath.str() +
"(" + I->getPath().str() + ")";
MemoryBuffer *Buffer =
MemoryBuffer::getNewMemBuffer(I->getSize(), FullMemberName.c_str());
memcpy((char*)Buffer->getBufferStart(), I->getData(), I->getSize());
Module *M = ParseBitcodeFile(Buffer, Context, ErrMessage);
delete Buffer;
if (!M)
return true;
Modules.push_back(M);
}
}
return false;
}
// Load just the symbol table from the archive file
bool
Archive::loadSymbolTable(std::string* ErrorMsg) {
// Set up parsing
members.clear();
symTab.clear();
const char *At = base;
const char *End = mapfile->getBufferEnd();
// Make sure we're dealing with an archive
if (!checkSignature(ErrorMsg))
return false;
At += 8; // Skip signature
// Parse the first file member header
const char* FirstFile = At;
ArchiveMember* mbr = parseMemberHeader(At, End, ErrorMsg);
if (!mbr)
return false;
if (mbr->isSVR4SymbolTable() || mbr->isBSD4SymbolTable()) {
// Skip the foreign symbol table, we don't do anything with it
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
delete mbr;
// Read the next one
FirstFile = At;
mbr = parseMemberHeader(At, End, ErrorMsg);
if (!mbr) {
delete mbr;
return false;
}
}
if (mbr->isStringTable()) {
// Process the string table entry
strtab.assign((const char*)mbr->getData(), mbr->getSize());
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
delete mbr;
// Get the next one
FirstFile = At;
mbr = parseMemberHeader(At, End, ErrorMsg);
if (!mbr) {
delete mbr;
return false;
}
}
// See if its the symbol table
if (mbr->isLLVMSymbolTable()) {
if (!parseSymbolTable(mbr->getData(), mbr->getSize(), ErrorMsg)) {
delete mbr;
return false;
}
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
delete mbr;
// Can't be any more symtab headers so just advance
FirstFile = At;
} else {
// There's no symbol table in the file. We have to rebuild it from scratch
// because the intent of this method is to get the symbol table loaded so
// it can be searched efficiently.
// Add the member to the members list
members.push_back(mbr);
}
firstFileOffset = FirstFile - base;
return true;
}
// Open the archive and load just the symbol tables
Archive* Archive::OpenAndLoadSymbols(const sys::Path& file,
LLVMContext& C,
std::string* ErrorMessage) {
std::auto_ptr<Archive> result ( new Archive(file, C) );
if (result->mapToMemory(ErrorMessage))
return 0;
if (!result->loadSymbolTable(ErrorMessage))
return 0;
return result.release();
}
// Look up one symbol in the symbol table and return the module that defines
// that symbol.
Module*
Archive::findModuleDefiningSymbol(const std::string& symbol,
std::string* ErrMsg) {
SymTabType::iterator SI = symTab.find(symbol);
if (SI == symTab.end())
return 0;
// The symbol table was previously constructed assuming that the members were
// written without the symbol table header. Because VBR encoding is used, the
// values could not be adjusted to account for the offset of the symbol table
// because that could affect the size of the symbol table due to VBR encoding.
// We now have to account for this by adjusting the offset by the size of the
// symbol table and its header.
unsigned fileOffset =
SI->second + // offset in symbol-table-less file
firstFileOffset; // add offset to first "real" file in archive
// See if the module is already loaded
ModuleMap::iterator MI = modules.find(fileOffset);
if (MI != modules.end())
return MI->second.first;
// Module hasn't been loaded yet, we need to load it
const char* modptr = base + fileOffset;
ArchiveMember* mbr = parseMemberHeader(modptr, mapfile->getBufferEnd(),
ErrMsg);
if (!mbr)
return 0;
// Now, load the bitcode module to get the Module.
std::string FullMemberName = archPath.str() + "(" +
mbr->getPath().str() + ")";
MemoryBuffer *Buffer =MemoryBuffer::getNewMemBuffer(mbr->getSize(),
FullMemberName.c_str());
memcpy((char*)Buffer->getBufferStart(), mbr->getData(), mbr->getSize());
Module *m = getLazyBitcodeModule(Buffer, Context, ErrMsg);
if (!m)
return 0;
modules.insert(std::make_pair(fileOffset, std::make_pair(m, mbr)));
return m;
}
// Look up multiple symbols in the symbol table and return a set of
// Modules that define those symbols.
bool
Archive::findModulesDefiningSymbols(std::set<std::string>& symbols,
std::set<Module*>& result,
std::string* error) {
if (!mapfile || !base) {
if (error)
*error = "Empty archive invalid for finding modules defining symbols";
return false;
}
if (symTab.empty()) {
// We don't have a symbol table, so we must build it now but lets also
// make sure that we populate the modules table as we do this to ensure
// that we don't load them twice when findModuleDefiningSymbol is called
// below.
// Get a pointer to the first file
const char* At = base + firstFileOffset;
const char* End = mapfile->getBufferEnd();
while ( At < End) {
// Compute the offset to be put in the symbol table
unsigned offset = At - base - firstFileOffset;
// Parse the file's header
ArchiveMember* mbr = parseMemberHeader(At, End, error);
if (!mbr)
return false;
// If it contains symbols
if (mbr->isBitcode()) {
// Get the symbols
std::vector<std::string> symbols;
std::string FullMemberName = archPath.str() + "(" +
mbr->getPath().str() + ")";
Module* M =
GetBitcodeSymbols((const unsigned char*)At, mbr->getSize(),
FullMemberName, Context, symbols, error);
if (M) {
// Insert the module's symbols into the symbol table
for (std::vector<std::string>::iterator I = symbols.begin(),
E=symbols.end(); I != E; ++I ) {
symTab.insert(std::make_pair(*I, offset));
}
// Insert the Module and the ArchiveMember into the table of
// modules.
modules.insert(std::make_pair(offset, std::make_pair(M, mbr)));
} else {
if (error)
*error = "Can't parse bitcode member: " +
mbr->getPath().str() + ": " + *error;
delete mbr;
return false;
}
}
// Go to the next file location
At += mbr->getSize();
if ((intptr_t(At) & 1) == 1)
At++;
}
}
// At this point we have a valid symbol table (one way or another) so we
// just use it to quickly find the symbols requested.
for (std::set<std::string>::iterator I=symbols.begin(),
E=symbols.end(); I != E;) {
// See if this symbol exists
Module* m = findModuleDefiningSymbol(*I,error);
if (m) {
// The symbol exists, insert the Module into our result, duplicates will
// be ignored.
result.insert(m);
// Remove the symbol now that its been resolved, being careful to
// post-increment the iterator.
symbols.erase(I++);
} else {
++I;
}
}
return true;
}
bool Archive::isBitcodeArchive() {
// Make sure the symTab has been loaded. In most cases this should have been
// done when the archive was constructed, but still, this is just in case.
if (symTab.empty())
if (!loadSymbolTable(0))
return false;
// Now that we know it's been loaded, return true
// if it has a size
if (symTab.size()) return true;
// We still can't be sure it isn't a bitcode archive
if (!loadArchive(0))
return false;
std::vector<Module *> Modules;
std::string ErrorMessage;
// Scan the archive, trying to load a bitcode member. We only load one to
// see if this works.
for (iterator I = begin(), E = end(); I != E; ++I) {
if (!I->isBitcode())
continue;
std::string FullMemberName =
archPath.str() + "(" + I->getPath().str() + ")";
MemoryBuffer *Buffer =
MemoryBuffer::getNewMemBuffer(I->getSize(), FullMemberName.c_str());
memcpy((char*)Buffer->getBufferStart(), I->getData(), I->getSize());
Module *M = ParseBitcodeFile(Buffer, Context);
delete Buffer;
if (!M)
return false; // Couldn't parse bitcode, not a bitcode archive.
delete M;
return true;
}
return false;
}
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