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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9903 91177308-0d34-0410-b5e6-96231b3b80d8
179 lines
5.9 KiB
C++
179 lines
5.9 KiB
C++
//===- ArchiveReader.cpp - Code to read LLVM bytecode from .a files -------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the ReadArchiveFile interface, which allows a linker to
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// read all of the LLVM bytecode files contained in a .a file. This file
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// understands the standard system .a file format. This can only handle the .a
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// variant prevalent on Linux systems so far, but may be extended. See
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// information in this source file for more information:
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// http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/bfd/archive.c?cvsroot=src
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Bytecode/Reader.h"
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#include "llvm/Module.h"
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#include "Config/sys/stat.h"
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#include "Config/sys/mman.h"
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#include "Config/fcntl.h"
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namespace llvm {
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namespace {
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struct ar_hdr {
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char name[16];
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char date[12];
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char uid[6];
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char gid[6];
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char mode[8];
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char size[10];
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char fmag[2]; // Always equal to '`\n'
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};
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enum ObjectType {
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UserObject, // A user .o/.bc file
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Unknown, // Unknown file, just ignore it
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SVR4LongFilename, // a "//" section used for long file names
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};
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}
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// getObjectType - Determine the type of object that this header represents.
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// This is capable of parsing the variety of special sections used for various
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// purposes.
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static enum ObjectType getObjectType(ar_hdr *H, unsigned Size) {
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// Check for sections with special names...
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if (!memcmp(H->name, "// ", 16))
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return SVR4LongFilename;
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// Check to see if it looks like an llvm object file...
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if (Size >= 4 && !memcmp(H+1, "llvm", 4))
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return UserObject;
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return Unknown;
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}
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static inline bool Error(std::string *ErrorStr, const char *Message) {
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if (ErrorStr) *ErrorStr = Message;
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return true;
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}
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static bool ParseLongFilenameSection(unsigned char *Buffer, unsigned Size,
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std::vector<std::string> &LongFilenames,
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std::string *S) {
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if (!LongFilenames.empty())
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return Error(S, "archive file contains multiple long filename entries");
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while (Size) {
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// Long filename entries are newline delimited to keep the archive readable.
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unsigned char *Ptr = (unsigned char*)memchr(Buffer, '\n', Size);
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if (Ptr == 0)
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return Error(S, "archive long filename entry doesn't end with newline!");
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assert(*Ptr == '\n');
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if (Ptr == Buffer) break; // Last entry contains just a newline.
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unsigned char *End = Ptr;
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if (End[-1] == '/') --End; // Remove trailing / from name
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LongFilenames.push_back(std::string(Buffer, End));
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Size -= Ptr-Buffer+1;
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Buffer = Ptr+1;
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}
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return false;
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}
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static bool ReadArchiveBuffer(const std::string &Filename,
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unsigned char *Buffer, unsigned Length,
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std::vector<Module*> &Objects,
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std::string *ErrorStr) {
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if (Length < 8 || memcmp(Buffer, "!<arch>\n", 8))
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return Error(ErrorStr, "signature incorrect for an archive file!");
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Buffer += 8; Length -= 8; // Skip the magic string.
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std::vector<std::string> LongFilenames;
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while (Length >= sizeof(ar_hdr)) {
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ar_hdr *Hdr = (ar_hdr*)Buffer;
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unsigned Size = atoi(Hdr->size);
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if (Size+sizeof(ar_hdr) > Length)
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return Error(ErrorStr, "invalid record length in archive file!");
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switch (getObjectType(Hdr, Size)) {
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case SVR4LongFilename:
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// If this is a long filename section, read all of the file names into the
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// LongFilenames vector.
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//
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if (ParseLongFilenameSection(Buffer+sizeof(ar_hdr), Size,
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LongFilenames, ErrorStr))
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return true;
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break;
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case UserObject: {
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Module *M = ParseBytecodeBuffer(Buffer+sizeof(ar_hdr), Size,
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Filename+":somefile", ErrorStr);
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if (!M) return true;
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Objects.push_back(M);
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break;
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}
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case Unknown:
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std::cerr << "ReadArchiveBuffer: WARNING: Skipping unknown file: ";
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std::cerr << std::string(Hdr->name, Hdr->name+sizeof(Hdr->name+1)) <<"\n";
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break; // Just ignore unknown files.
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}
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// Round Size up to an even number...
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Size = (Size+1)/2*2;
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Buffer += sizeof(ar_hdr)+Size; // Move to the next entry
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Length -= sizeof(ar_hdr)+Size;
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}
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return Length != 0;
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}
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// ReadArchiveFile - Read bytecode files from the specified .a file, returning
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// true on error, or false on success. This does not support reading files from
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// standard input.
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//
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bool ReadArchiveFile(const std::string &Filename, std::vector<Module*> &Objects,
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std::string *ErrorStr) {
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int FD = open(Filename.c_str(), O_RDONLY);
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if (FD == -1)
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return Error(ErrorStr, "Error opening file!");
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// Stat the file to get its length...
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struct stat StatBuf;
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if (fstat(FD, &StatBuf) == -1 || StatBuf.st_size == 0)
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return Error(ErrorStr, "Error stat'ing file!");
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// mmap in the file all at once...
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int Length = StatBuf.st_size;
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unsigned char *Buffer = (unsigned char*)mmap(0, Length, PROT_READ,
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MAP_PRIVATE, FD, 0);
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if (Buffer == (unsigned char*)MAP_FAILED)
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return Error(ErrorStr, "Error mmapping file!");
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// Parse the archive files we mmap'ped in
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bool Result = ReadArchiveBuffer(Filename, Buffer, Length, Objects, ErrorStr);
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// Unmmap the archive...
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munmap((char*)Buffer, Length);
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if (Result) // Free any loaded objects
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while (!Objects.empty()) {
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delete Objects.back();
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Objects.pop_back();
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}
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return Result;
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}
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} // End llvm namespace
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