llvm-6502/lib/Bytecode/Reader/ArchiveReader.cpp
Brian Gaeke 2c61d7b240 Implement skeletal support for __.SYMDEF (ranlib) sections in archives.
Correctly parse the Long Filename section of the archive.
When reading in archive members, set their ModuleIDs to
 "ARCHIVENAME(MEMBERNAME)", as is traditional.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10043 91177308-0d34-0410-b5e6-96231b3b80d8
2003-11-16 23:08:48 +00:00

204 lines
6.8 KiB
C++

//===- 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 "Config/sys/stat.h"
#include "Config/sys/mman.h"
#include "Config/fcntl.h"
#include <cstdlib>
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, unsigned Size) {
// Check for sections with special names...
if (!memcmp(H->name, "__.SYMDEF ", 16))
return ArchiveSymbolTable;
if (!memcmp(H->name, "// ", 16))
return SVR4LongFilename;
// Check to see if it looks like an llvm object file...
if (Size >= 4 && !memcmp(H+1, "llvm", 4))
return UserObject;
return Unknown;
}
static inline bool Error(std::string *ErrorStr, const char *Message) {
if (ErrorStr) *ErrorStr = Message;
return true;
}
static bool ParseLongFilenameSection(unsigned char *Buffer, unsigned Size,
std::vector<std::string> &LongFilenames,
std::string *S) {
if (!LongFilenames.empty())
return Error(S, "archive file contains multiple long filename entries");
while (Size) {
// Long filename entries are newline delimited to keep the archive readable.
unsigned char *Ptr = (unsigned char*)memchr(Buffer, '\n', Size);
if (Ptr == 0)
return Error(S, "archive long filename entry doesn't end with newline!");
assert(*Ptr == '\n');
if (Ptr == Buffer) break; // Last entry contains just a newline.
unsigned char *End = Ptr;
if (End[-1] == '/') --End; // Remove trailing / from name
LongFilenames.push_back(std::string(Buffer, End));
Size -= Ptr-Buffer+1;
Buffer = Ptr+1;
}
return false;
}
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 Size = atoi(Hdr->size);
if (Size+sizeof(ar_hdr) > Length)
return Error(ErrorStr, "invalid record length in archive file!");
// Get name of archive member.
char *startp = Hdr->name;
char *endp = strchr (startp, '/');
if (startp == endp && isdigit (Hdr->name[1])) {
// Long filenames are abbreviated as "/I", where I is a decimal
// index into the LongFilenames vector.
unsigned Index = atoi (&Hdr->name[1]);
assert (LongFilenames.size () > Index
&& "Long filename for archive member not found");
startp = &LongFilenames[Index];
endp = strchr (startp, '/');
}
std::string MemberName (startp, endp);
std::string FullMemberName = ArchiveName + "(" + MemberName + ")";
switch (getObjectType(Hdr, Size)) {
case SVR4LongFilename:
// If this is a long filename section, read all of the file names into the
// LongFilenames vector.
LongFilenames.assign (Buffer+sizeof(ar_hdr), Buffer+sizeof(ar_hdr)+Size);
break;
case UserObject: {
Module *M = ParseBytecodeBuffer(Buffer+sizeof(ar_hdr), Size,
FullMemberName, ErrorStr);
if (!M) return true;
Objects.push_back(M);
break;
}
case ArchiveSymbolTable:
if (ParseSymbolTableSection(Buffer+sizeof(ar_hdr), Size, ErrorStr))
return true;
break;
default:
std::cerr << "ReadArchiveBuffer: WARNING: Skipping unknown file: "
<< FullMemberName << "\n";
break; // Just ignore unknown files.
}
// Round Size up to an even number...
Size = (Size+1)/2*2;
Buffer += sizeof(ar_hdr)+Size; // Move to the next entry
Length -= sizeof(ar_hdr)+Size;
}
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 ReadArchiveFile(const std::string &Filename, std::vector<Module*> &Objects,
std::string *ErrorStr) {
int FD = open(Filename.c_str(), O_RDONLY);
if (FD == -1)
return Error(ErrorStr, "Error opening file!");
// Stat the file to get its length...
struct stat StatBuf;
if (fstat(FD, &StatBuf) == -1 || StatBuf.st_size == 0)
return Error(ErrorStr, "Error stat'ing file!");
// mmap in the file all at once...
int Length = StatBuf.st_size;
unsigned char *Buffer = (unsigned char*)mmap(0, Length, PROT_READ,
MAP_PRIVATE, FD, 0);
if (Buffer == (unsigned char*)MAP_FAILED)
return Error(ErrorStr, "Error mmapping file!");
// Parse the archive files we mmap'ped in
bool Result = ReadArchiveBuffer(Filename, Buffer, Length, Objects, ErrorStr);
// Unmmap the archive...
munmap((char*)Buffer, Length);
if (Result) // Free any loaded objects
while (!Objects.empty()) {
delete Objects.back();
Objects.pop_back();
}
return Result;
}
} // End llvm namespace