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libelf.d
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libelf.d
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/**
* Compiler implementation of the
* $(LINK2 http://www.dlang.org, D programming language).
*
* Copyright: Copyright (C) 1999-2018 by The D Language Foundation, All Rights Reserved
* Authors: $(LINK2 http://www.digitalmars.com, Walter Bright)
* License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost License 1.0)
* Source: $(LINK2 https://github.com/dlang/dmd/blob/master/src/dmd/libelf.d, _libelf.d)
* Documentation: https://dlang.org/phobos/dmd_libelf.html
* Coverage: https://codecov.io/gh/dlang/dmd/src/master/src/dmd/libelf.d
*/
module dmd.libelf;
version(Windows) {}
else version(OSX) {}
else:
import core.stdc.time;
import core.stdc.string;
import core.stdc.stdlib;
import core.stdc.stdio;
import core.sys.posix.sys.stat;
import core.sys.posix.unistd;
import dmd.globals;
import dmd.lib;
import dmd.utils;
import dmd.root.array;
import dmd.root.file;
import dmd.root.filename;
import dmd.root.outbuffer;
import dmd.root.port;
import dmd.root.rmem;
import dmd.root.stringtable;
import dmd.scanelf;
enum LOG = false;
struct ElfObjSymbol
{
const(char)[] name;
ElfObjModule* om;
}
alias ElfObjModules = Array!(ElfObjModule*);
alias ElfObjSymbols = Array!(ElfObjSymbol*);
final class LibElf : Library
{
ElfObjModules objmodules; // ElfObjModule[]
ElfObjSymbols objsymbols; // ElfObjSymbol[]
StringTable tab;
extern (D) this()
{
tab._init(14000);
}
/***************************************
* Add object module or library to the library.
* Examine the buffer to see which it is.
* If the buffer is NULL, use module_name as the file name
* and load the file.
*/
override void addObject(const(char)* module_name, const ubyte[] buffer)
{
if (!module_name)
module_name = "";
static if (LOG)
{
printf("LibElf::addObject(%s)\n", module_name);
}
void corrupt(int reason)
{
error("corrupt ELF object module %s %d", module_name, reason);
}
int fromfile = 0;
auto buf = buffer.ptr;
auto buflen = buffer.length;
if (!buf)
{
assert(module_name[0]);
File* file = File.create(cast(char*)module_name);
readFile(Loc.initial, file);
buf = file.buffer;
buflen = file.len;
file._ref = 1;
fromfile = 1;
}
if (buflen < 16)
{
static if (LOG)
{
printf("buf = %p, buflen = %d\n", buf, buflen);
}
return corrupt(__LINE__);
}
if (memcmp(buf, cast(char*)"!<arch>\n", 8) == 0)
{
/* Library file.
* Pull each object module out of the library and add it
* to the object module array.
*/
static if (LOG)
{
printf("archive, buf = %p, buflen = %d\n", buf, buflen);
}
uint offset = 8;
char* symtab = null;
uint symtab_size = 0;
char* filenametab = null;
uint filenametab_size = 0;
uint mstart = cast(uint)objmodules.dim;
while (offset < buflen)
{
if (offset + ElfLibHeader.sizeof >= buflen)
return corrupt(__LINE__);
ElfLibHeader* header = cast(ElfLibHeader*)(cast(ubyte*)buf + offset);
offset += ElfLibHeader.sizeof;
char* endptr = null;
uint size = cast(uint)strtoul(header.file_size.ptr, &endptr, 10);
if (endptr >= header.file_size.ptr + 10 || *endptr != ' ')
return corrupt(__LINE__);
if (offset + size > buflen)
return corrupt(__LINE__);
if (header.object_name[0] == '/' && header.object_name[1] == ' ')
{
/* Instead of rescanning the object modules we pull from a
* library, just use the already created symbol table.
*/
if (symtab)
return corrupt(__LINE__);
symtab = cast(char*)buf + offset;
symtab_size = size;
if (size < 4)
return corrupt(__LINE__);
}
else if (header.object_name[0] == '/' && header.object_name[1] == '/')
{
/* This is the file name table, save it for later.
*/
if (filenametab)
return corrupt(__LINE__);
filenametab = cast(char*)buf + offset;
filenametab_size = size;
}
else
{
auto om = new ElfObjModule();
om.base = cast(ubyte*)buf + offset; /*- sizeof(ElfLibHeader)*/
om.length = size;
om.offset = 0;
if (header.object_name[0] == '/')
{
/* Pick long name out of file name table
*/
uint foff = cast(uint)strtoul(header.object_name.ptr + 1, &endptr, 10);
uint i;
for (i = 0; 1; i++)
{
if (foff + i >= filenametab_size)
return corrupt(__LINE__);
char c = filenametab[foff + i];
if (c == '/')
break;
}
auto n = cast(char*)malloc(i + 1);
assert(n);
memcpy(n, filenametab + foff, i);
n[i] = 0;
om.name = n[0 .. i];
}
else
{
/* Pick short name out of header
*/
auto n = cast(char*)malloc(ELF_OBJECT_NAME_SIZE);
assert(n);
for (int i = 0; 1; i++)
{
if (i == ELF_OBJECT_NAME_SIZE)
return corrupt(__LINE__);
char c = header.object_name[i];
if (c == '/')
{
n[i] = 0;
om.name = n[0 .. i];
break;
}
n[i] = c;
}
}
om.name_offset = -1;
om.file_time = strtoul(header.file_time.ptr, &endptr, 10);
om.user_id = cast(uint)strtoul(header.user_id.ptr, &endptr, 10);
om.group_id = cast(uint)strtoul(header.group_id.ptr, &endptr, 10);
om.file_mode = cast(uint)strtoul(header.file_mode.ptr, &endptr, 8);
om.scan = 0; // don't scan object module for symbols
objmodules.push(om);
}
offset += (size + 1) & ~1;
}
if (offset != buflen)
return corrupt(__LINE__);
/* Scan the library's symbol table, and insert it into our own.
* We use this instead of rescanning the object module, because
* the library's creator may have a different idea of what symbols
* go into the symbol table than we do.
* This is also probably faster.
*/
uint nsymbols = Port.readlongBE(symtab);
char* s = symtab + 4 + nsymbols * 4;
if (4 + nsymbols * (4 + 1) > symtab_size)
return corrupt(__LINE__);
for (uint i = 0; i < nsymbols; i++)
{
const(char)[] name = s[0 .. strlen(s)];
s += name.length + 1;
if (s - symtab > symtab_size)
return corrupt(__LINE__);
uint moff = Port.readlongBE(symtab + 4 + i * 4);
//printf("symtab[%d] moff = %x %x, name = %s\n", i, moff, moff + sizeof(Header), name.ptr);
for (uint m = mstart; 1; m++)
{
if (m == objmodules.dim)
return corrupt(__LINE__); // didn't find it
ElfObjModule* om = objmodules[m];
//printf("\t%x\n", (char *)om.base - (char *)buf);
if (moff + ElfLibHeader.sizeof == cast(char*)om.base - cast(char*)buf)
{
addSymbol(om, name, 1);
//if (mstart == m)
// mstart++;
break;
}
}
}
return;
}
/* It's an object module
*/
auto om = new ElfObjModule();
om.base = cast(ubyte*)buf;
om.length = cast(uint)buflen;
om.offset = 0;
auto n = cast(char*)FileName.name(module_name); // remove path, but not extension
om.name = n[0 .. strlen(n)];
om.name_offset = -1;
om.scan = 1;
if (fromfile)
{
stat_t statbuf;
int i = stat(module_name, &statbuf);
if (i == -1) // error, errno is set
return corrupt(__LINE__);
om.file_time = statbuf.st_ctime;
om.user_id = statbuf.st_uid;
om.group_id = statbuf.st_gid;
om.file_mode = statbuf.st_mode;
}
else
{
/* Mock things up for the object module file that never was
* actually written out.
*/
__gshared uid_t uid;
__gshared gid_t gid;
__gshared int _init;
if (!_init)
{
_init = 1;
uid = getuid();
gid = getgid();
}
time(&om.file_time);
om.user_id = uid;
om.group_id = gid;
om.file_mode = (1 << 15) | (6 << 6) | (4 << 3); // 0100640
}
objmodules.push(om);
}
/*****************************************************************************/
void addSymbol(ElfObjModule* om, const(char)[] name, int pickAny = 0)
{
static if (LOG)
{
printf("LibElf::addSymbol(%s, %s, %d)\n", om.name.ptr, name.ptr, pickAny);
}
StringValue* s = tab.insert(name.ptr, name.length, null);
if (!s)
{
// already in table
if (!pickAny)
{
s = tab.lookup(name.ptr, name.length);
assert(s);
ElfObjSymbol* os = cast(ElfObjSymbol*)s.ptrvalue;
error("multiple definition of %s: %s and %s: %s", om.name.ptr, name.ptr, os.om.name.ptr, os.name.ptr);
}
}
else
{
auto os = new ElfObjSymbol();
os.name = xarraydup(name);
os.om = om;
s.ptrvalue = cast(void*)os;
objsymbols.push(os);
}
}
private:
/************************************
* Scan single object module for dictionary symbols.
* Send those symbols to LibElf::addSymbol().
*/
void scanObjModule(ElfObjModule* om)
{
static if (LOG)
{
printf("LibElf::scanObjModule(%s)\n", om.name.ptr);
}
extern (D) void addSymbol(const(char)[] name, int pickAny)
{
this.addSymbol(om, name, pickAny);
}
scanElfObjModule(&addSymbol, om.base[0 .. om.length], om.name.ptr, loc);
}
/*****************************************************************************/
/*****************************************************************************/
/**********************************************
* Create and write library to libbuf.
* The library consists of:
* !<arch>\n
* header
* dictionary
* object modules...
*/
protected override void WriteLibToBuffer(OutBuffer* libbuf)
{
static if (LOG)
{
printf("LibElf::WriteLibToBuffer()\n");
}
/************* Scan Object Modules for Symbols ******************/
foreach (om; objmodules)
{
if (om.scan)
{
scanObjModule(om);
}
}
/************* Determine string section ******************/
/* The string section is where we store long file names.
*/
uint noffset = 0;
foreach (om; objmodules)
{
size_t len = om.name.length;
if (len >= ELF_OBJECT_NAME_SIZE)
{
om.name_offset = noffset;
noffset += len + 2;
}
else
om.name_offset = -1;
}
static if (LOG)
{
printf("\tnoffset = x%x\n", noffset);
}
/************* Determine module offsets ******************/
uint moffset = 8 + ElfLibHeader.sizeof + 4;
foreach (os; objsymbols)
{
moffset += 4 + os.name.length + 1;
}
uint hoffset = moffset;
static if (LOG)
{
printf("\tmoffset = x%x\n", moffset);
}
moffset += moffset & 1;
if (noffset)
moffset += ElfLibHeader.sizeof + noffset;
foreach (om; objmodules)
{
moffset += moffset & 1;
om.offset = moffset;
moffset += ElfLibHeader.sizeof + om.length;
}
libbuf.reserve(moffset);
/************* Write the library ******************/
libbuf.write("!<arch>\n".ptr, 8);
ElfObjModule om;
om.name_offset = -1;
om.base = null;
om.length = cast(uint)(hoffset - (8 + ElfLibHeader.sizeof));
om.offset = 8;
om.name = "";
.time(&om.file_time);
om.user_id = 0;
om.group_id = 0;
om.file_mode = 0;
ElfLibHeader h;
ElfOmToHeader(&h, &om);
libbuf.write(&h, h.sizeof);
char[4] buf;
Port.writelongBE(cast(uint)objsymbols.dim, buf.ptr);
libbuf.write(buf.ptr, 4);
foreach (os; objsymbols)
{
Port.writelongBE(os.om.offset, buf.ptr);
libbuf.write(buf.ptr, 4);
}
foreach (os; objsymbols)
{
libbuf.writestring(os.name);
libbuf.writeByte(0);
}
static if (LOG)
{
printf("\tlibbuf.moffset = x%x\n", libbuf.offset);
}
/* Write out the string section
*/
if (noffset)
{
if (libbuf.offset & 1)
libbuf.writeByte('\n');
// header
memset(&h, ' ', ElfLibHeader.sizeof);
h.object_name[0] = '/';
h.object_name[1] = '/';
size_t len = sprintf(h.file_size.ptr, "%u", noffset);
assert(len < 10);
h.file_size[len] = ' ';
h.trailer[0] = '`';
h.trailer[1] = '\n';
libbuf.write(&h, h.sizeof);
foreach (om2; objmodules)
{
if (om2.name_offset >= 0)
{
libbuf.writestring(om2.name);
libbuf.writeByte('/');
libbuf.writeByte('\n');
}
}
}
/* Write out each of the object modules
*/
foreach (om2; objmodules)
{
if (libbuf.offset & 1)
libbuf.writeByte('\n'); // module alignment
assert(libbuf.offset == om2.offset);
ElfOmToHeader(&h, om2);
libbuf.write(&h, h.sizeof); // module header
libbuf.write(om2.base, om2.length); // module contents
}
static if (LOG)
{
printf("moffset = x%x, libbuf.offset = x%x\n", moffset, libbuf.offset);
}
assert(libbuf.offset == moffset);
}
}
extern (C++) Library LibElf_factory()
{
return new LibElf();
}
/*****************************************************************************/
/*****************************************************************************/
struct ElfObjModule
{
ubyte* base; // where are we holding it in memory
uint length; // in bytes
uint offset; // offset from start of library
const(char)[] name; // module name (file name) with terminating 0
int name_offset; // if not -1, offset into string table of name
time_t file_time; // file time
uint user_id;
uint group_id;
uint file_mode;
int scan; // 1 means scan for symbols
}
enum ELF_OBJECT_NAME_SIZE = 16;
struct ElfLibHeader
{
char[ELF_OBJECT_NAME_SIZE] object_name;
char[12] file_time;
char[6] user_id;
char[6] group_id;
char[8] file_mode; // in octal
char[10] file_size;
char[2] trailer;
}
extern (C++) void ElfOmToHeader(ElfLibHeader* h, ElfObjModule* om)
{
char* buffer = cast(char*)h;
// user_id and group_id are padded on 6 characters in Header struct.
// Squashing to 0 if more than 999999.
if (om.user_id > 999999)
om.user_id = 0;
if (om.group_id > 999999)
om.group_id = 0;
size_t len;
if (om.name_offset == -1)
{
// "name/ 1423563789 5000 5000 100640 3068 `\n"
// |^^^^^^^^^^^^^^^|^^^^^^^^^^^|^^^^^|^^^^^|^^^^^^^|^^^^^^^^^|^^
// name file_time u_id gr_id fmode fsize trailer
len = snprintf(buffer, ElfLibHeader.sizeof, "%-16s%-12llu%-6u%-6u%-8o%-10u`", om.name.ptr, cast(long)om.file_time, om.user_id, om.group_id, om.file_mode, om.length);
// adding '/' after the name field
const(size_t) name_length = om.name.length;
assert(name_length < ELF_OBJECT_NAME_SIZE);
buffer[name_length] = '/';
}
else
{
// "/162007 1423563789 5000 5000 100640 3068 `\n"
// |^^^^^^^^^^^^^^^|^^^^^^^^^^^|^^^^^|^^^^^|^^^^^^^|^^^^^^^^^|^^
// name_offset file_time u_id gr_id fmode fsize trailer
len = snprintf(buffer, ElfLibHeader.sizeof, "/%-15d%-12llu%-6u%-6u%-8o%-10u`", om.name_offset, cast(long)om.file_time, om.user_id, om.group_id, om.file_mode, om.length);
}
assert(ElfLibHeader.sizeof > 0 && len == ElfLibHeader.sizeof - 1);
// replace trailing \0 with \n
buffer[len] = '\n';
}