sheetjs/packages/otorp/src/otorp.ts
2022-01-31 06:41:23 -05:00

118 lines
3.9 KiB
TypeScript

/*! otorp (C) 2013-present SheetJS -- http://sheetjs.com */
import { u8indexOf, u8str, u8_to_dataview } from "../../../modules/src/util";
import { parse_macho } from "./macho";
import { Descriptor, parse_FileDescriptor, write_FileDescriptor } from './descriptor';
interface OtorpEntry {
name: string;
proto: string;
}
export { OtorpEntry };
/** Find and stringify all relevant protobuf defs */
function otorp(buf: Uint8Array, builtins = false): OtorpEntry[] {
var res = proto_offsets(buf);
var registry: {[key: string]: Descriptor} = {};
var names: Set<string> = new Set();
var out: OtorpEntry[] = [];
res.forEach((r, i) => {
if(!builtins && r[1].startsWith("google/protobuf/")) return;
var b = buf.slice(r[0], i < res.length - 1 ? res[i+1][0] : buf.length);
var pb = parse_FileDescriptorProto(b/*, r[1]*/);
names.add(r[1]);
registry[r[1]] = pb;
});
names.forEach(name => {
/* ensure partial ordering by dependencies */
names.delete(name);
var pb = registry[name];
var doit = (pb.dependency||[]).every((d: string) => !names.has(d));
if(!doit) { names.add(name); return; }
var dups = res.filter(r => r[1] == name);
if(dups.length == 1) return out.push({ name, proto: write_FileDescriptor(pb) });
/* in a fat binary, compare the defs for x86_64/aarch64 */
var pbs = dups.map(r => {
var i = res.indexOf(r);
var b = buf.slice(r[0], i < res.length - 1 ? res[i+1][0] : buf.length);
var pb = parse_FileDescriptorProto(b/*, r[1]*/);
return write_FileDescriptor(pb);
});
for(var l = 1; l < pbs.length; ++l) if(pbs[l] != pbs[0]) throw new Error(`Conflicting definitions for ${name} at offsets 0x${dups[0][0].toString(16)} and 0x${dups[l][0].toString(16)}`);
return out.push({ name, proto: pbs[0] });
});
return out;
}
export default otorp;
/** Determine if an address is being referenced */
var is_referenced = (buf: Uint8Array, pos: number): boolean => {
var dv = u8_to_dataview(buf);
/* Search for LEA reference (x86) */
for(var leaddr = 0; leaddr > -1 && leaddr < pos; leaddr = u8indexOf(buf, 0x8D, leaddr + 1))
if(dv.getUint32(leaddr + 2, true) == pos - leaddr - 6) return true;
/* Search for absolute reference to address */
try {
var headers = parse_macho(buf);
for(var i = 0; i < headers.length; ++i) {
if(pos < headers[i].offset || pos > headers[i].offset + headers[i].size) continue;
var b = headers[i].data;
var p = pos - headers[i].offset;
var ref = new Uint8Array([0,0,0,0,0,0,0,0]);
var dv = u8_to_dataview(ref);
dv.setInt32(0, p, true);
if(u8indexOf(b, ref, 0) > 0) return true;
ref[4] = 0x01;
if(u8indexOf(b, ref, 0) > 0) return true;
}
} catch(e) {}
return false;
};
type OffsetList = Array<[number, string, number, number]>;
/** Generate a list of potential starting points */
var proto_offsets = (buf: Uint8Array): OffsetList => {
var meta = parse_macho(buf);
var out: OffsetList = [];
var off = 0;
/* note: this loop only works for names < 128 chars */
search: while((off = u8indexOf(buf, ".proto", off + 1)) > -1) {
var pos = off;
off += 6;
while(off - pos < 256 && buf[pos] != off - pos - 1) {
if(buf[pos] > 0x7F || buf[pos] < 0x20) continue search;
--pos;
}
if(off - pos > 250) continue;
var name = u8str(buf.slice(pos + 1, off));
if(buf[--pos] != 0x0A) continue;
if(!is_referenced(buf, pos)) { console.error(`Reference to ${name} not found`); continue; }
var bin = meta.find(m => m.offset <= pos && m.offset + m.size >= pos);
out.push([pos, name, bin?.type || -1, bin?.subtype || -1]);
}
return out;
};
/** Parse a descriptor that starts with the first byte of the supplied buffer */
var parse_FileDescriptorProto = (buf: Uint8Array): Descriptor => {
var l = buf.length;
while(l > 0) try {
var b = buf.slice(0,l);
var o = parse_FileDescriptor(b);
return o;
} catch(e) {
var m = e.message.match(/at offset (\d+)/);
if(m && parseInt(m[1], 10) < buf.length) l = parseInt(m[1], 10) - 1;
else --l;
}
throw new RangeError("no protobuf message in range");
};