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//===- ArchiveReader.cpp - Code to read LLVM bytecode from .a files -------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the ReadArchiveFile interface, which allows a linker to
// read all of the LLVM bytecode files contained in a .a file. This file
// understands the standard system .a file format. This can only handle the .a
// variant prevalent on Linux systems so far, but may be extended. See
// information in this source file for more information:
// http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/bfd/archive.c?cvsroot=src
//
//===----------------------------------------------------------------------===//
#include "llvm/Bytecode/Reader.h"
#include "llvm/Module.h"
#include "llvm/Support/FileUtilities.h"
#include <cstdlib>
#include <iostream>
using namespace llvm;
namespace {
struct ar_hdr {
char name[16];
char date[12];
char uid[6];
char gid[6];
char mode[8];
char size[10];
char fmag[2]; // Always equal to '`\n'
};
enum ObjectType {
UserObject, // A user .o/.bc file
Unknown, // Unknown file, just ignore it
SVR4LongFilename, // a "//" section used for long file names
ArchiveSymbolTable, // Symbol table produced by ranlib.
};
}
/// getObjectType - Determine the type of object that this header represents.
/// This is capable of parsing the variety of special sections used for various
/// purposes.
///
static enum ObjectType getObjectType(ar_hdr *H, std::string MemberName,
unsigned char *MemberData, unsigned Size) {
// Check for sections with special names...
if (MemberName == "__.SYMDEF " || MemberName == "__.SYMDEF SORTED")
return ArchiveSymbolTable;
else if (MemberName == "// ")
return SVR4LongFilename;
// Check to see if it looks like an llvm object file...
if (Size >= 4 && !memcmp(MemberData, "llvm", 4))
return UserObject;
return Unknown;
}
static inline bool Error(std::string *ErrorStr, const char *Message) {
if (ErrorStr) *ErrorStr = Message;
return true;
}
static bool ParseSymbolTableSection(unsigned char *Buffer, unsigned Size,
std::string *S) {
// Currently not supported (succeeds without doing anything)
return false;
}
static bool ReadArchiveBuffer(const std::string &ArchiveName,
unsigned char *Buffer, unsigned Length,
std::vector<Module*> &Objects,
std::string *ErrorStr) {
if (Length < 8 || memcmp(Buffer, "!<arch>\n", 8))
return Error(ErrorStr, "signature incorrect for an archive file!");
Buffer += 8; Length -= 8; // Skip the magic string.
std::vector<char> LongFilenames;
while (Length >= sizeof(ar_hdr)) {
ar_hdr *Hdr = (ar_hdr*)Buffer;
unsigned SizeFromHeader = atoi(Hdr->size);
if (SizeFromHeader + sizeof(ar_hdr) > Length)
return Error(ErrorStr, "invalid record length in archive file!");
unsigned char *MemberData = Buffer + sizeof(ar_hdr);
unsigned MemberSize = SizeFromHeader;
// Get name of archive member.
char *startp = Hdr->name;
char *endp = (char *) memchr (startp, '/', sizeof(ar_hdr));
if (memcmp (Hdr->name, "#1/", 3) == 0) {
// 4.4BSD/MacOSX long filenames are abbreviated as "#1/L", where L is an
// ASCII-coded decimal number representing the length of the name buffer,
// which is prepended to the archive member's contents.
unsigned NameLength = atoi (&Hdr->name[3]);
startp = (char *) MemberData;
endp = startp + NameLength;
MemberData += NameLength;
MemberSize -= NameLength;
} else if (startp == endp && isdigit (Hdr->name[1])) {
// SVR4 long filenames are abbreviated as "/I", where I is
// an ASCII-coded decimal index into the LongFilenames vector.
unsigned NameIndex = atoi (&Hdr->name[1]);
assert (LongFilenames.size () > NameIndex
&& "SVR4-style long filename for archive member not found");
startp = &LongFilenames[NameIndex];
endp = strchr (startp, '/');
} else if (startp == endp && Hdr->name[1] == '/') {
// This is for the SVR4 long filename table (there might be other
// names starting with // but I don't know about them). Make sure that
// getObjectType sees it.
endp = &Hdr->name[sizeof (Hdr->name)];
}
if (!endp) {
// 4.4BSD/MacOSX *short* filenames are not guaranteed to have a
// terminator. Start at the end of the field and backtrack over spaces.
endp = startp + sizeof(Hdr->name);
while (endp[-1] == ' ')
--endp;
}
std::string MemberName (startp, endp);
std::string FullMemberName = ArchiveName + "(" + MemberName + ")";
switch (getObjectType(Hdr, MemberName, MemberData, MemberSize)) {
case SVR4LongFilename:
// If this is a long filename section, read all of the file names into the
// LongFilenames vector.
LongFilenames.assign (MemberData, MemberData + MemberSize);
break;
case UserObject: {
Module *M = ParseBytecodeBuffer(MemberData, MemberSize,
FullMemberName, ErrorStr);
if (!M) return true;
Objects.push_back(M);
break;
}
case ArchiveSymbolTable:
if (ParseSymbolTableSection(MemberData, MemberSize, ErrorStr))
return true;
break;
default:
std::cerr << "ReadArchiveBuffer: WARNING: Skipping unknown file: "
<< FullMemberName << "\n";
break; // Just ignore unknown files.
}
// Round SizeFromHeader up to an even number...
SizeFromHeader = (SizeFromHeader+1)/2*2;
Buffer += sizeof(ar_hdr)+SizeFromHeader; // Move to the next entry
Length -= sizeof(ar_hdr)+SizeFromHeader;
}
return Length != 0;
}
// ReadArchiveFile - Read bytecode files from the specified .a file, returning
// true on error, or false on success. This does not support reading files from
// standard input.
//
bool llvm::ReadArchiveFile(const std::string &Filename,
std::vector<Module*> &Objects,std::string *ErrorStr){
unsigned Length;
// mmap in the file all at once...
unsigned char *Buffer =
(unsigned char*)ReadFileIntoAddressSpace(Filename, Length);
if (Buffer == 0) {
if (ErrorStr) *ErrorStr = "Error reading file '" + Filename + "'!";
return true;
}
// Parse the archive files we mmap'ped in
bool Result = ReadArchiveBuffer(Filename, Buffer, Length, Objects, ErrorStr);
// Unmmap the archive...
UnmapFileFromAddressSpace(Buffer, Length);
if (Result) // Free any loaded objects
while (!Objects.empty()) {
delete Objects.back();
Objects.pop_back();
}
return Result;
}
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