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#include "lib9.h"
#include <a.out.h>
#include <dynld.h>
static ulong
get2(uchar *b)
{
return (b[0] << 8) | b[1];
}
static ulong
get4(uchar *b)
{
return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
}
static ulong
lgetbe(ulong l)
{
union {
ulong l;
uchar c[4];
} u;
u.l = l;
return get4(u.c);
}
Dynsym*
dynfindsym(char *s, Dynsym *tab, int ntab)
{
int n, n2, d;
Dynsym *t, *m;
t = tab;
n = ntab;
while(n > 0){
n2 = n>>1;
m = t+n2;
d = strcmp(s, m->name);
if(d < 0){
n = n2;
continue;
}
if(d > 0){
t = m+1;
n -= n2+1;
continue;
}
return m;
}
return nil;
}
void*
dynimport(Dynobj *o, char *name, ulong sig)
{
Dynsym *t;
t = dynfindsym(name, o->export, o->nexport);
if(t == nil || sig != 0 && t->sig != 0 && t->sig != sig)
return nil;
return (void*)t->addr;
}
int
dyntabsize(Dynsym *t)
{
int n;
for(n = 0; t->name != nil; t++)
n++;
return n;
}
void
dynobjfree(Dynobj *o)
{
if(o != nil){
free(o->base);
free(o->import);
free(o);
}
}
void
dynfreeimport(Dynobj *o)
{
free(o->import);
o->import = nil;
o->nimport = 0;
}
static char Ereloc[] = "error reading object file";
Dynobj*
dynloadgen(void *file, long (*rd)(void*,void*,long), vlong (*sk)(void*,vlong,int), void (*werr)(char*), Dynsym *tab, int ntab, ulong maxsize)
{
int i, m, n, ni, nr, relsize;
ulong syms, entry, sig, p, a;
uchar *base;
Exec e;
Dynsym *t;
Dynobj *l;
char *s, *err, buf[64];
uchar *reldata, *rp, *ep;
vlong off;
err = Ereloc; /* default */
off = (*sk)(file, 0, 1);
l = mallocz(sizeof(Dynobj), 1);
if(l == nil){
err = "can't allocate Dynobj";
goto Error;
}
if((*rd)(file, &e, sizeof(Exec)) != sizeof(Exec))
goto Error;
if(lgetbe(e.magic) != dynmagic()){
err = "not dynamic object file or wrong platform";
goto Error;
}
l->text = lgetbe(e.text);
l->data = lgetbe(e.data);
l->bss = lgetbe(e.bss);
syms = lgetbe(e.syms)+lgetbe(e.spsz)+lgetbe(e.pcsz);
entry = lgetbe(e.entry);
l->size = l->text + l->data + l->bss;
if(entry < 0 || entry >= l->size || entry & 3){
err = "invalid export table pointer (entry point)";
goto Error;
}
if(maxsize && l->size >= maxsize){
snprint(buf, sizeof(buf), "%lud: object too big", l->size);
err = buf;
goto Error;
}
l->base = base = malloc(l->size);
if(base == nil){
err = "out of memory: loading object file";
goto Error;
}
l->export = (Dynsym*)(base+entry);
if((*rd)(file, base, l->text+l->data) != l->text+l->data)
goto Error;
memset(base+l->text+l->data, 0, l->bss);
if((*sk)(file, syms, 1) < 0)
goto Error;
if((*rd)(file, buf, 4) != 4)
goto Error;
relsize = get4((uchar*)buf); /* always contains at least an import count (might be zero) */
if(relsize < 4)
goto Error;
reldata = malloc(relsize);
if(reldata == nil){
err = "out of memory: relocation data";
goto Error;
}
if((*rd)(file, reldata, relsize) != relsize)
goto Error;
rp = reldata;
ep = reldata+relsize;
ni = get4(rp);
rp += 4;
if(ni < 0 || ni > 8000)
goto Error; /* implausible size */
l->nimport = ni;
l->import = malloc(ni*sizeof(Dynsym*));
if(l->import == nil){
err = "out of memory: symbol table";
goto Error;
}
for(i = 0; i < ni; i++){
if(rp+5 > ep)
goto Error;
sig = get4(rp);
rp += 4;
s = (char*)rp;
while(*rp++)
if(rp >= ep)
goto Error;
t = dynfindsym(s, tab, ntab);
if(t == nil){
snprint(buf, sizeof(buf), "undefined symbol: %s", s);
err = buf;
goto Error;
}
if(sig != 0 && t->sig != 0 && t->sig != sig){
snprint(buf, sizeof(buf), "signature mismatch: %s (%lux != %lux)", s, sig, t->sig);
err = buf;
goto Error;
}
l->import[i] = t;
}
a = 0;
if(rp+4 > ep)
goto Error;
nr = get4(rp);
rp += 4;
for(i = 0; i < nr; i++){
if(rp >= ep)
goto Error;
m = *rp++;
n = m>>6;
if(rp+(1<<n) > ep)
goto Error;
switch(n){
case 0:
p = *rp++;
break;
case 1:
p = get2(rp);
rp += 2;
break;
case 2:
p = get4(rp);
rp += 4;
break;
default:
goto Error;
}
a += p;
err = dynreloc(base, a, m&0xf, l->import, ni);
if(err != nil){
snprint(buf, sizeof(buf), "dynamic object: %s", err);
err = buf;
goto Error;
}
}
free(reldata);
/* could check relocated export table here */
l->nexport = dyntabsize(l->export);
segflush(base, l->text);
return l;
Error:
if(off >= 0)
(*sk)(file, off, 0); /* restore original file offset */
(*werr)(err);
dynobjfree(l);
return nil;
}
int
dynloadable(void* file, long (*rd)(void*,void*,long), vlong (*sk)(void*,vlong,int))
{
long magic;
if((*rd)(file, &magic, sizeof(magic)) != sizeof(magic)){
(*sk)(file, -(signed int)sizeof(magic), 1);
return 0;
}
(*sk)(file, -(signed int)sizeof(magic), 1);
return lgetbe(magic) == dynmagic();
}
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