src/cmd/ld/pe.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
addpesection
chksectoff
chksectseg
peinit
pewrite
strput
initdynimport
addimports
scmp
initdynexport
addexports
dope
strtbladd
newPEDWARFSection
addsym
addsymtable
setpersrc
addpersrc
asmbpe
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// PE (Portable Executable) file writing
// http://www.microsoft.com/whdc/system/platform/firmware/PECOFF.mspx

#include "l.h"
#include "../ld/lib.h"
#include "../ld/pe.h"
#include "../ld/dwarf.h"

// DOS stub that prints out
// "This program cannot be run in DOS mode."
static char dosstub[] =
{
        0x4d, 0x5a, 0x90, 0x00, 0x03, 0x00, 0x04, 0x00,
        0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0x00, 0x00,
        0x8b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00,
        0x0e, 0x1f, 0xba, 0x0e, 0x00, 0xb4, 0x09, 0xcd,
        0x21, 0xb8, 0x01, 0x4c, 0xcd, 0x21, 0x54, 0x68,
        0x69, 0x73, 0x20, 0x70, 0x72, 0x6f, 0x67, 0x72,
        0x61, 0x6d, 0x20, 0x63, 0x61, 0x6e, 0x6e, 0x6f,
        0x74, 0x20, 0x62, 0x65, 0x20, 0x72, 0x75, 0x6e,
        0x20, 0x69, 0x6e, 0x20, 0x44, 0x4f, 0x53, 0x20,
        0x6d, 0x6f, 0x64, 0x65, 0x2e, 0x0d, 0x0d, 0x0a,
        0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

static LSym *rsrcsym;

static char* strtbl;
static int strtblnextoff;
static int strtblsize;

int32 PESECTHEADR;
int32 PEFILEHEADR;

static int pe64;
static int nsect;
static int nextsectoff;
static int nextfileoff;
static int textsect;
static int datasect;

static IMAGE_FILE_HEADER fh;
static IMAGE_OPTIONAL_HEADER oh;
static PE64_IMAGE_OPTIONAL_HEADER oh64;
static IMAGE_SECTION_HEADER sh[16];
static IMAGE_DATA_DIRECTORY* dd;

#define set(n, v)       (pe64 ? (oh64.n = v) : (oh.n = v))
#define put(v)          (pe64 ? vputl(v) : lputl(v))

typedef struct Imp Imp;
struct Imp {
        LSym* s;
        uvlong off;
        Imp* next;
};

typedef struct Dll Dll;
struct Dll {
        char* name;
        uvlong nameoff;
        uvlong thunkoff;
        Imp* ms;
        Dll* next;
};

static Dll* dr;

static LSym *dexport[1024];
static int nexport;

typedef struct COFFSym COFFSym;
struct COFFSym
{
        LSym* sym;
        int strtbloff;
        int sect;
        vlong value;
};

static COFFSym* coffsym;
static int ncoffsym;

static IMAGE_SECTION_HEADER*
addpesection(char *name, int sectsize, int filesize)
{
        IMAGE_SECTION_HEADER *h;

        if(nsect == 16) {
                diag("too many sections");
                errorexit();
        }
        h = &sh[nsect++];
        strncpy((char*)h->Name, name, sizeof(h->Name));
        h->VirtualSize = sectsize;
        h->VirtualAddress = nextsectoff;
        nextsectoff = rnd(nextsectoff+sectsize, PESECTALIGN);
        h->PointerToRawData = nextfileoff;
        if(filesize > 0) {
                h->SizeOfRawData = rnd(filesize, PEFILEALIGN);
                nextfileoff += h->SizeOfRawData;
        }
        return h;
}

static void
chksectoff(IMAGE_SECTION_HEADER *h, vlong off)
{
        if(off != h->PointerToRawData) {
                diag("%s.PointerToRawData = %#llux, want %#llux", (char *)h->Name, (vlong)h->PointerToRawData, off);
                errorexit();
        }
}

static void
chksectseg(IMAGE_SECTION_HEADER *h, Segment *s)
{
        if(s->vaddr-PEBASE != h->VirtualAddress) {
                diag("%s.VirtualAddress = %#llux, want %#llux", (char *)h->Name, (vlong)h->VirtualAddress, (vlong)(s->vaddr-PEBASE));
                errorexit();
        }
        if(s->fileoff != h->PointerToRawData) {
                diag("%s.PointerToRawData = %#llux, want %#llux", (char *)h->Name, (vlong)h->PointerToRawData, (vlong)(s->fileoff));
                errorexit();
        }
}

void
peinit(void)
{
        int32 l;

        switch(thechar) {
        // 64-bit architectures
        case '6':
                pe64 = 1;
                l = sizeof(oh64);
                dd = oh64.DataDirectory;
                break;
        // 32-bit architectures
        default:
                l = sizeof(oh);
                dd = oh.DataDirectory;
                break;
        }
        
        PEFILEHEADR = rnd(sizeof(dosstub)+sizeof(fh)+l+sizeof(sh), PEFILEALIGN);
        PESECTHEADR = rnd(PEFILEHEADR, PESECTALIGN);
        nextsectoff = PESECTHEADR;
        nextfileoff = PEFILEHEADR;

        // some mingw libs depend on this symbol, for example, FindPESectionByName
        xdefine("__image_base__", SDATA, PEBASE);
        xdefine("_image_base__", SDATA, PEBASE);
}

static void
pewrite(void)
{
        cseek(0);
        cwrite(dosstub, sizeof dosstub);
        strnput("PE", 4);
        // TODO: This code should not assume that the
        // memory representation is little-endian or
        // that the structs are packed identically to
        // their file representation.
        cwrite(&fh, sizeof fh);
        if(pe64)
                cwrite(&oh64, sizeof oh64);
        else
                cwrite(&oh, sizeof oh);
        cwrite(sh, nsect * sizeof sh[0]);
}

static void
strput(char *s)
{
        int n;

        for(n=0; *s; n++)
                cput(*s++);
        cput('\0');
        n++;
        // string must be padded to even size
        if(n%2)
                cput('\0');
}

static Dll* 
initdynimport(void)
{
        Imp *m;
        Dll *d;
        LSym *s, *dynamic;

        dr = nil;
        m = nil;
        for(s = ctxt->allsym; s != S; s = s->allsym) {
                if(!s->reachable || s->type != SDYNIMPORT)
                        continue;
                for(d = dr; d != nil; d = d->next) {
                        if(strcmp(d->name,s->dynimplib) == 0) {
                                m = mal(sizeof *m);
                                break;
                        }
                }
                if(d == nil) {
                        d = mal(sizeof *d);
                        d->name = s->dynimplib;
                        d->next = dr;
                        dr = d;
                        m = mal(sizeof *m);
                }
                m->s = s;
                m->next = d->ms;
                d->ms = m;
        }
        
        dynamic = linklookup(ctxt, ".windynamic", 0);
        dynamic->reachable = 1;
        dynamic->type = SWINDOWS;
        for(d = dr; d != nil; d = d->next) {
                for(m = d->ms; m != nil; m = m->next) {
                        m->s->type = SWINDOWS | SSUB;
                        m->s->sub = dynamic->sub;
                        dynamic->sub = m->s;
                        m->s->value = dynamic->size;
                        dynamic->size += PtrSize;
                }
                dynamic->size += PtrSize;
        }
                
        return dr;
}

static void
addimports(IMAGE_SECTION_HEADER *datsect)
{
        IMAGE_SECTION_HEADER *isect;
        uvlong n, oftbase, ftbase;
        vlong startoff, endoff;
        Imp *m;
        Dll *d;
        LSym* dynamic;
        
        startoff = cpos();
        dynamic = linklookup(ctxt, ".windynamic", 0);

        // skip import descriptor table (will write it later)
        n = 0;
        for(d = dr; d != nil; d = d->next)
                n++;
        cseek(startoff + sizeof(IMAGE_IMPORT_DESCRIPTOR) * (n + 1));

        // write dll names
        for(d = dr; d != nil; d = d->next) {
                d->nameoff = cpos() - startoff;
                strput(d->name);
        }

        // write function names
        for(d = dr; d != nil; d = d->next) {
                for(m = d->ms; m != nil; m = m->next) {
                        m->off = nextsectoff + cpos() - startoff;
                        wputl(0); // hint
                        strput(m->s->extname);
                }
        }
        
        // write OriginalFirstThunks
        oftbase = cpos() - startoff;
        n = cpos();
        for(d = dr; d != nil; d = d->next) {
                d->thunkoff = cpos() - n;
                for(m = d->ms; m != nil; m = m->next)
                        put(m->off);
                put(0);
        }

        // add pe section and pad it at the end
        n = cpos() - startoff;
        isect = addpesection(".idata", n, n);
        isect->Characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA|
                IMAGE_SCN_MEM_READ|IMAGE_SCN_MEM_WRITE;
        chksectoff(isect, startoff);
        strnput("", isect->SizeOfRawData - n);
        endoff = cpos();

        // write FirstThunks (allocated in .data section)
        ftbase = dynamic->value - datsect->VirtualAddress - PEBASE;
        cseek(datsect->PointerToRawData + ftbase);
        for(d = dr; d != nil; d = d->next) {
                for(m = d->ms; m != nil; m = m->next)
                        put(m->off);
                put(0);
        }
        
        // finally write import descriptor table
        cseek(startoff);
        for(d = dr; d != nil; d = d->next) {
                lputl(isect->VirtualAddress + oftbase + d->thunkoff);
                lputl(0);
                lputl(0);
                lputl(isect->VirtualAddress + d->nameoff);
                lputl(datsect->VirtualAddress + ftbase + d->thunkoff);
        }
        lputl(0); //end
        lputl(0);
        lputl(0);
        lputl(0);
        lputl(0);
        
        // update data directory
        dd[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress = isect->VirtualAddress;
        dd[IMAGE_DIRECTORY_ENTRY_IMPORT].Size = isect->VirtualSize;
        dd[IMAGE_DIRECTORY_ENTRY_IAT].VirtualAddress = dynamic->value - PEBASE;
        dd[IMAGE_DIRECTORY_ENTRY_IAT].Size = dynamic->size;

        cseek(endoff);
}

static int
scmp(const void *p1, const void *p2)
{
        LSym *s1, *s2;

        s1 = *(LSym**)p1;
        s2 = *(LSym**)p2;
        return strcmp(s1->extname, s2->extname);
}

static void
initdynexport(void)
{
        LSym *s;
        
        nexport = 0;
        for(s = ctxt->allsym; s != S; s = s->allsym) {
                if(!s->reachable || !(s->cgoexport & CgoExportDynamic))
                        continue;
                if(nexport+1 > sizeof(dexport)/sizeof(dexport[0])) {
                        diag("pe dynexport table is full");
                        errorexit();
                }
                
                dexport[nexport] = s;
                nexport++;
        }
        
        qsort(dexport, nexport, sizeof dexport[0], scmp);
}

void
addexports(void)
{
        IMAGE_SECTION_HEADER *sect;
        IMAGE_EXPORT_DIRECTORY e;
        int size, i, va, va_name, va_addr, va_na, v;

        size = sizeof e + 10*nexport + strlen(outfile) + 1;
        for(i=0; i<nexport; i++)
                size += strlen(dexport[i]->extname) + 1;
        
        if (nexport == 0)
                return;
                
        sect = addpesection(".edata", size, size);
        sect->Characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA|IMAGE_SCN_MEM_READ;
        chksectoff(sect, cpos());
        va = sect->VirtualAddress;
        dd[IMAGE_DIRECTORY_ENTRY_EXPORT].VirtualAddress = va;
        dd[IMAGE_DIRECTORY_ENTRY_EXPORT].Size = sect->VirtualSize;

        va_name = va + sizeof e + nexport*4;
        va_addr = va + sizeof e;
        va_na = va + sizeof e + nexport*8;

        e.Characteristics = 0;
        e.MajorVersion = 0;
        e.MinorVersion = 0;
        e.NumberOfFunctions = nexport;
        e.NumberOfNames = nexport;
        e.Name = va + sizeof e + nexport*10; // Program names.
        e.Base = 1;
        e.AddressOfFunctions = va_addr;
        e.AddressOfNames = va_name;
        e.AddressOfNameOrdinals = va_na;
        // put IMAGE_EXPORT_DIRECTORY
        for (i=0; i<sizeof(e); i++)
                cput(((char*)&e)[i]);
        // put EXPORT Address Table
        for(i=0; i<nexport; i++)
                lputl(dexport[i]->value - PEBASE);              
        // put EXPORT Name Pointer Table
        v = e.Name + strlen(outfile)+1;
        for(i=0; i<nexport; i++) {
                lputl(v);
                v += strlen(dexport[i]->extname)+1;
        }
        // put EXPORT Ordinal Table
        for(i=0; i<nexport; i++)
                wputl(i);
        // put Names
        strnput(outfile, strlen(outfile)+1);
        for(i=0; i<nexport; i++)
                strnput(dexport[i]->extname, strlen(dexport[i]->extname)+1);
        strnput("", sect->SizeOfRawData - size);
}

void
dope(void)
{
        LSym *rel;

        /* relocation table */
        rel = linklookup(ctxt, ".rel", 0);
        rel->reachable = 1;
        rel->type = SELFROSECT;

        initdynimport();
        initdynexport();
}

static int
strtbladd(char *name)
{
        int newsize, thisoff;

        newsize = strtblnextoff + strlen(name) + 1;
        if(newsize > strtblsize) {
                strtblsize = 2 * (newsize + (1<<18));
                strtbl = realloc(strtbl, strtblsize);
        }
        thisoff = strtblnextoff+4; // first string starts at offset=4
        strcpy(&strtbl[strtblnextoff], name);
        strtblnextoff += strlen(name);
        strtbl[strtblnextoff] = 0;
        strtblnextoff++;
        return thisoff;
}

/*
 * For more than 8 characters section names, name contains a slash (/) that is 
 * followed by an ASCII representation of a decimal number that is an offset into 
 * the string table. 
 * reference: pecoff_v8.docx Page 24.
 * <http://www.microsoft.com/whdc/system/platform/firmware/PECOFFdwn.mspx>
 */
IMAGE_SECTION_HEADER*
newPEDWARFSection(char *name, vlong size)
{
        IMAGE_SECTION_HEADER *h;
        char s[8];
        int off;

        if(size == 0)
                return nil;

        off = strtbladd(name);
        sprint(s, "/%d\0", off);
        h = addpesection(s, size, size);
        h->Characteristics = IMAGE_SCN_MEM_READ|
                IMAGE_SCN_MEM_DISCARDABLE;

        return h;
}

static void
addsym(LSym *s, char *name, int type, vlong addr, vlong size, int ver, LSym *gotype)
{
        COFFSym *cs;
        USED(name);
        USED(addr);
        USED(size);
        USED(ver);
        USED(gotype);

        if(s == nil)
                return;

        if(s->sect == nil)
                return;

        switch(type) {
        default:
                return;
        case 'D':
        case 'B':
        case 'T':
                break;
        }

        if(coffsym) {
                cs = &coffsym[ncoffsym];
                cs->sym = s;
                if(strlen(s->name) > 8)
                        cs->strtbloff = strtbladd(s->name);
                if(s->value >= segdata.vaddr) {
                        cs->value = s->value - segdata.vaddr;
                        cs->sect = datasect;
                } else if(s->value >= segtext.vaddr) {
                        cs->value = s->value - segtext.vaddr;
                        cs->sect = textsect;
                } else {
                        cs->value = 0;
                        cs->sect = 0;
                        diag("addsym %#llx", addr);
                }
        }
        ncoffsym++;
}

static void
addsymtable(void)
{
        IMAGE_SECTION_HEADER *h;
        int i, size;
        COFFSym *s;

        if(!debug['s']) {
                genasmsym(addsym);
                coffsym = mal(ncoffsym * sizeof coffsym[0]);
                ncoffsym = 0;
                genasmsym(addsym);
        }

        size = strtblnextoff + 4 + 18*ncoffsym;
        h = addpesection(".symtab", size, size);
        h->Characteristics = IMAGE_SCN_MEM_READ|
                IMAGE_SCN_MEM_DISCARDABLE;
        chksectoff(h, cpos());
        fh.PointerToSymbolTable = cpos();
        fh.NumberOfSymbols = ncoffsym;
        
        // put COFF symbol table
        for (i=0; i<ncoffsym; i++) {
                s = &coffsym[i];
                if(s->strtbloff == 0)
                        strnput(s->sym->name, 8);
                else {
                        lputl(0);
                        lputl(s->strtbloff);
                }
                lputl(s->value);
                wputl(s->sect);
                wputl(0x0308);  // "array of structs"
                cput(2);        // storage class: external
                cput(0);        // no aux entries
        }

        // put COFF string table
        lputl(strtblnextoff + 4);
        for (i=0; i<strtblnextoff; i++)
                cput(strtbl[i]);
        strnput("", h->SizeOfRawData - size);
}

void
setpersrc(LSym *sym)
{
        if(rsrcsym != nil)
                diag("too many .rsrc sections");
        
        rsrcsym = sym;
}

void
addpersrc(void)
{
        IMAGE_SECTION_HEADER *h;
        uchar *p;
        uint32 val;
        Reloc *r;

        if(rsrcsym == nil)
                return;
        
        h = addpesection(".rsrc", rsrcsym->size, rsrcsym->size);
        h->Characteristics = IMAGE_SCN_MEM_READ|
                IMAGE_SCN_MEM_WRITE | IMAGE_SCN_CNT_INITIALIZED_DATA;
        chksectoff(h, cpos());
        // relocation
        for(r=rsrcsym->r; r<rsrcsym->r+rsrcsym->nr; r++) {
                p = rsrcsym->p + r->off;
                val = h->VirtualAddress + r->add;
                // 32-bit little-endian
                p[0] = val;
                p[1] = val>>8;
                p[2] = val>>16;
                p[3] = val>>24;
        }
        cwrite(rsrcsym->p, rsrcsym->size);
        strnput("", h->SizeOfRawData - rsrcsym->size);

        // update data directory
        dd[IMAGE_DIRECTORY_ENTRY_RESOURCE].VirtualAddress = h->VirtualAddress;
        dd[IMAGE_DIRECTORY_ENTRY_RESOURCE].Size = h->VirtualSize;
}

void
asmbpe(void)
{
        IMAGE_SECTION_HEADER *t, *d;

        switch(thechar) {
        default:
                diag("unknown PE architecture");
                errorexit();
        case '6':
                fh.Machine = IMAGE_FILE_MACHINE_AMD64;
                break;
        case '8':
                fh.Machine = IMAGE_FILE_MACHINE_I386;
                break;
        }

        t = addpesection(".text", segtext.len, segtext.len);
        t->Characteristics = IMAGE_SCN_CNT_CODE|
                IMAGE_SCN_CNT_INITIALIZED_DATA|
                IMAGE_SCN_MEM_EXECUTE|IMAGE_SCN_MEM_READ;
        chksectseg(t, &segtext);
        textsect = nsect;

        d = addpesection(".data", segdata.len, segdata.filelen);
        d->Characteristics = IMAGE_SCN_CNT_INITIALIZED_DATA|
                IMAGE_SCN_MEM_READ|IMAGE_SCN_MEM_WRITE;
        chksectseg(d, &segdata);
        datasect = nsect;

        if(!debug['s'])
                dwarfaddpeheaders();

        cseek(nextfileoff);
        addimports(d);
        addexports();
        addsymtable();
        addpersrc();

        fh.NumberOfSections = nsect;
        fh.TimeDateStamp = time(0);
        fh.Characteristics = IMAGE_FILE_RELOCS_STRIPPED|
                IMAGE_FILE_EXECUTABLE_IMAGE|IMAGE_FILE_DEBUG_STRIPPED;
        if (pe64) {
                fh.SizeOfOptionalHeader = sizeof(oh64);
                fh.Characteristics |= IMAGE_FILE_LARGE_ADDRESS_AWARE;
                set(Magic, 0x20b);      // PE32+
        } else {
                fh.SizeOfOptionalHeader = sizeof(oh);
                fh.Characteristics |= IMAGE_FILE_32BIT_MACHINE;
                set(Magic, 0x10b);      // PE32
                oh.BaseOfData = d->VirtualAddress;
        }
        set(MajorLinkerVersion, 3);
        set(MinorLinkerVersion, 0);
        set(SizeOfCode, t->SizeOfRawData);
        set(SizeOfInitializedData, d->SizeOfRawData);
        set(SizeOfUninitializedData, 0);
        set(AddressOfEntryPoint, entryvalue()-PEBASE);
        set(BaseOfCode, t->VirtualAddress);
        set(ImageBase, PEBASE);
        set(SectionAlignment, PESECTALIGN);
        set(FileAlignment, PEFILEALIGN);
        set(MajorOperatingSystemVersion, 4);
        set(MinorOperatingSystemVersion, 0);
        set(MajorImageVersion, 1);
        set(MinorImageVersion, 0);
        set(MajorSubsystemVersion, 4);
        set(MinorSubsystemVersion, 0);
        set(SizeOfImage, nextsectoff);
        set(SizeOfHeaders, PEFILEHEADR);
        if(strcmp(headstring, "windowsgui") == 0)
                set(Subsystem, IMAGE_SUBSYSTEM_WINDOWS_GUI);
        else
                set(Subsystem, IMAGE_SUBSYSTEM_WINDOWS_CUI);

        // Disable stack growth as we don't want Windows to
        // fiddle with the thread stack limits, which we set
        // ourselves to circumvent the stack checks in the
        // Windows exception dispatcher.
        // Commit size must be strictly less than reserve
        // size otherwise reserve will be rounded up to a
        // larger size, as verified with VMMap.

        // Go code would be OK with 64k stacks, but we need larger stacks for cgo.
        // That default stack reserve size affects only the main thread,
        // for other threads we specify stack size in runtime explicitly
        // (runtime knows whether cgo is enabled or not).
        // If you change stack reserve sizes here,
        // change STACKSIZE in runtime/cgo/gcc_windows_{386,amd64}.c as well.
        if(!iscgo) {
                set(SizeOfStackReserve, 0x00010000);
                set(SizeOfStackCommit, 0x0000ffff);
        } else {
                set(SizeOfStackReserve, pe64 ? 0x00200000 : 0x00100000);
                // account for 2 guard pages
                set(SizeOfStackCommit, (pe64 ? 0x00200000 : 0x00100000) - 0x2000);
        }
        set(SizeOfHeapReserve, 0x00100000);
        set(SizeOfHeapCommit, 0x00001000);
        set(NumberOfRvaAndSizes, 16);

        pewrite();
}
/* [<][>][^][v][top][bottom][index][help] */
root/src/cmd/ld/pe.c

DEFINITIONS
