1 //===- ArchiveReader.cpp - Code to read LLVM bytecode from .a files -------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the ReadArchiveFile interface, which allows a linker to
11 // read all of the LLVM bytecode files contained in a .a file. This file
12 // understands the standard system .a file format. This can only handle the .a
13 // variant prevalent on Linux systems so far, but may be extended. See
14 // information in this source file for more information:
15 // http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/bfd/archive.c?cvsroot=src
17 //===----------------------------------------------------------------------===//
19 #include "llvm/Bytecode/Reader.h"
20 #include "llvm/Module.h"
21 #include "Config/sys/stat.h"
22 #include "Config/sys/mman.h"
23 #include "Config/fcntl.h"
33 char fmag[2]; // Always equal to '`\n'
37 UserObject, // A user .o/.bc file
38 Unknown, // Unknown file, just ignore it
39 SVR4LongFilename, // a "//" section used for long file names
44 // getObjectType - Determine the type of object that this header represents.
45 // This is capable of parsing the variety of special sections used for various
47 static enum ObjectType getObjectType(ar_hdr *H, unsigned Size) {
48 // Check for sections with special names...
49 if (!memcmp(H->name, "// ", 16))
50 return SVR4LongFilename;
52 // Check to see if it looks like an llvm object file...
53 if (Size >= 4 && !memcmp(H+1, "llvm", 4))
60 static inline bool Error(std::string *ErrorStr, const char *Message) {
61 if (ErrorStr) *ErrorStr = Message;
65 static bool ParseLongFilenameSection(unsigned char *Buffer, unsigned Size,
66 std::vector<std::string> &LongFilenames,
68 if (!LongFilenames.empty())
69 return Error(S, "archive file contains multiple long filename entries");
72 // Long filename entries are newline delimited to keep the archive readable.
73 unsigned char *Ptr = (unsigned char*)memchr(Buffer, '\n', Size);
75 return Error(S, "archive long filename entry doesn't end with newline!");
78 if (Ptr == Buffer) break; // Last entry contains just a newline.
80 unsigned char *End = Ptr;
81 if (End[-1] == '/') --End; // Remove trailing / from name
83 LongFilenames.push_back(std::string(Buffer, End));
92 static bool ReadArchiveBuffer(const std::string &Filename,
93 unsigned char *Buffer, unsigned Length,
94 std::vector<Module*> &Objects,
95 std::string *ErrorStr) {
96 if (Length < 8 || memcmp(Buffer, "!<arch>\n", 8))
97 return Error(ErrorStr, "signature incorrect for an archive file!");
98 Buffer += 8; Length -= 8; // Skip the magic string.
100 std::vector<std::string> LongFilenames;
102 while (Length >= sizeof(ar_hdr)) {
103 ar_hdr *Hdr = (ar_hdr*)Buffer;
104 unsigned Size = atoi(Hdr->size);
105 if (Size+sizeof(ar_hdr) > Length)
106 return Error(ErrorStr, "invalid record length in archive file!");
108 switch (getObjectType(Hdr, Size)) {
109 case SVR4LongFilename:
110 // If this is a long filename section, read all of the file names into the
111 // LongFilenames vector.
113 if (ParseLongFilenameSection(Buffer+sizeof(ar_hdr), Size,
114 LongFilenames, ErrorStr))
118 Module *M = ParseBytecodeBuffer(Buffer+sizeof(ar_hdr), Size,
119 Filename+":somefile", ErrorStr);
121 Objects.push_back(M);
125 std::cerr << "ReadArchiveBuffer: WARNING: Skipping unknown file: ";
126 std::cerr << std::string(Hdr->name, Hdr->name+sizeof(Hdr->name+1)) <<"\n";
127 break; // Just ignore unknown files.
130 // Round Size up to an even number...
132 Buffer += sizeof(ar_hdr)+Size; // Move to the next entry
133 Length -= sizeof(ar_hdr)+Size;
140 // ReadArchiveFile - Read bytecode files from the specified .a file, returning
141 // true on error, or false on success. This does not support reading files from
144 bool ReadArchiveFile(const std::string &Filename, std::vector<Module*> &Objects,
145 std::string *ErrorStr) {
146 int FD = open(Filename.c_str(), O_RDONLY);
148 return Error(ErrorStr, "Error opening file!");
150 // Stat the file to get its length...
152 if (fstat(FD, &StatBuf) == -1 || StatBuf.st_size == 0)
153 return Error(ErrorStr, "Error stat'ing file!");
155 // mmap in the file all at once...
156 int Length = StatBuf.st_size;
157 unsigned char *Buffer = (unsigned char*)mmap(0, Length, PROT_READ,
159 if (Buffer == (unsigned char*)MAP_FAILED)
160 return Error(ErrorStr, "Error mmapping file!");
162 // Parse the archive files we mmap'ped in
163 bool Result = ReadArchiveBuffer(Filename, Buffer, Length, Objects, ErrorStr);
165 // Unmmap the archive...
166 munmap((char*)Buffer, Length);
168 if (Result) // Free any loaded objects
169 while (!Objects.empty()) {
170 delete Objects.back();