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stage2 macho: make file structure compatible with codesign tool

master
Jakub Konka 2020-11-22 12:33:39 +01:00
parent e7db372864
commit 59fe3d447d
1 changed files with 114 additions and 140 deletions
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254
src/link/MachO.zig
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@ -125,6 +125,9 @@ got_section_index: ?u16 = null,
entry_addr: ?u64 = null,
// TODO move this into each Segment aggregator
linkedit_segment_next_offset: ?u32 = null,
/// Table of all local symbols
/// Internally references string table for names (which are optional).
local_symbols: std.ArrayListUnmanaged(macho.nlist_64) = .{},
@ -330,35 +333,14 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
const tracy = trace(@src());
defer tracy.end();
// Unfortunately these have to be buffered and done at the end because MachO does not allow
// mixing local, global and undefined symbols within a symbol table.
try self.writeAllGlobalSymbols();
try self.writeAllUndefSymbols();
try self.writeStringTable();
switch (self.base.options.output_mode) {
.Exe => {
// Write export trie.
try self.writeExportTrie();
if (self.entry_addr) |addr| {
// Update LC_MAIN with entry offset.
const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const main_cmd = &self.load_commands.items[self.main_cmd_index.?].EntryPoint;
main_cmd.entryoff = addr - text_segment.vmaddr;
}
{
// Update dynamic symbol table.
const nlocals = @intCast(u32, self.local_symbols.items.len);
const nglobals = @intCast(u32, self.global_symbols.items.len);
const nundefs = @intCast(u32, self.undef_symbols.items.len);
const dysymtab = &self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
dysymtab.nlocalsym = nlocals;
dysymtab.iextdefsym = nlocals;
dysymtab.nextdefsym = nglobals;
dysymtab.iundefsym = nlocals + nglobals;
dysymtab.nundefsym = nundefs;
}
if (self.dylinker_cmd_dirty) {
// Write path to dyld loader.
var off: usize = @sizeOf(macho.mach_header_64);
@ -385,32 +367,22 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
try self.base.file.?.pwriteAll(mem.spanZ(LIB_SYSTEM_PATH), off);
self.libsystem_cmd_dirty = false;
}
try self.writeExportTrie();
try self.writeSymbolTable();
try self.writeStringTable();
// Preallocate space for the code signature.
// We need to do this at this stage so that we have the load commands with proper values
// written out to the file.
// The most important here is to have the correct vm and filesize of the __LINKEDIT segment
// where the code signature goes into.
try self.writeCodeSignaturePadding();
},
.Obj => {},
.Lib => return error.TODOImplementWritingLibFiles,
}
{
// Update symbol table.
const nlocals = @intCast(u32, self.local_symbols.items.len);
const nglobals = @intCast(u32, self.global_symbols.items.len);
const nundefs = @intCast(u32, self.undef_symbols.items.len);
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
symtab.nsyms = nlocals + nglobals + nundefs;
}
// TODO rework how we preallocate space for the entire __LINKEDIT segment instead of
// doing dynamic updates like this.
if (self.code_signature_cmd_index) |i| {
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const code_sig = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
linkedit.filesize = code_sig.dataoff + code_sig.datasize - linkedit.fileoff;
} else {
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
linkedit.filesize = symtab.stroff + symtab.strsize - linkedit.fileoff;
}
if (self.cmd_table_dirty) {
try self.writeCmdHeaders();
try self.writeMachOHeader();
@ -1003,8 +975,6 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
symbol.n_type = macho.N_SECT;
symbol.n_sect = @intCast(u8, self.text_section_index.?) + 1;
symbol.n_desc = 0;
// TODO this write could be avoided if no fields of the symbol were changed.
try self.writeSymbol(decl.link.macho.local_sym_index);
} else {
const decl_name = mem.spanZ(decl.name);
const name_str_index = try self.makeString(decl_name);
@ -1020,8 +990,6 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
.n_value = addr,
};
self.offset_table.items[decl.link.macho.offset_table_index] = addr;
try self.writeSymbol(decl.link.macho.local_sym_index);
try self.writeOffsetTableEntry(decl.link.macho.offset_table_index);
}
@ -1241,7 +1209,9 @@ pub fn populateMissingMetadata(self: *MachO) !void {
data_segment.nsects += 1;
const file_size = @sizeOf(u64) * self.base.options.symbol_count_hint;
const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
// TODO looking for free space should be done *within* a segment it belongs to
// const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
const off = @intCast(u32, data_segment.fileoff);
log.debug("found __got section free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
@ -1263,7 +1233,6 @@ pub fn populateMissingMetadata(self: *MachO) !void {
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
data_segment.vmsize = segment_size;
data_segment.filesize = segment_size;
data_segment.fileoff = off;
self.cmd_table_dirty = true;
}
if (self.linkedit_segment_cmd_index == null) {
@ -1271,6 +1240,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
const data_segment = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
const maxprot = macho.VM_PROT_READ | macho.VM_PROT_WRITE | macho.VM_PROT_EXECUTE;
const initprot = macho.VM_PROT_READ;
const off = data_segment.fileoff + data_segment.filesize;
try self.load_commands.append(self.base.allocator, .{
.Segment = .{
.cmd = macho.LC_SEGMENT_64,
@ -1278,7 +1248,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
.segname = makeStaticString("__LINKEDIT"),
.vmaddr = data_segment.vmaddr + data_segment.vmsize,
.vmsize = 0,
.fileoff = 0,
.fileoff = off,
.filesize = 0,
.maxprot = maxprot,
.initprot = initprot,
@ -1286,6 +1256,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
.flags = 0,
},
});
self.linkedit_segment_next_offset = @intCast(u32, off);
self.cmd_table_dirty = true;
}
if (self.dyld_info_cmd_index == null) {
@ -1438,62 +1409,6 @@ pub fn populateMissingMetadata(self: *MachO) !void {
},
});
}
{
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const dyld_info = &self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfo;
if (dyld_info.export_off == 0) {
const nsyms = self.base.options.symbol_count_hint;
const file_size = @sizeOf(u64) * nsyms;
const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
log.debug("found export trie free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
dyld_info.export_off = off;
dyld_info.export_size = @intCast(u32, file_size);
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
linkedit.vmsize += segment_size;
linkedit.fileoff = off;
}
}
{
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
if (symtab.symoff == 0) {
const nsyms = self.base.options.symbol_count_hint;
const file_size = @sizeOf(macho.nlist_64) * nsyms;
const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
log.debug("found symbol table free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
symtab.symoff = off;
symtab.nsyms = @intCast(u32, nsyms);
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
linkedit.vmsize += segment_size;
}
if (symtab.stroff == 0) {
try self.string_table.append(self.base.allocator, 0);
const file_size = @intCast(u32, self.string_table.items.len);
const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
log.debug("found string table free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
symtab.stroff = off;
symtab.strsize = file_size;
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
linkedit.vmsize += segment_size;
}
}
{
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const code_sig = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
if (code_sig.dataoff == 0) {
const file_size = 0x1000; // TODO what is a good guesstimate for initial code signature?
const off = @intCast(u32, self.findFreeSpace(file_size, self.page_size));
log.debug("found code signature free space 0x{x} to 0x{x}\n", .{ off, off + file_size });
code_sig.dataoff = off;
code_sig.datasize = file_size;
const segment_size = mem.alignForwardGeneric(u64, file_size, self.page_size);
linkedit.vmsize += segment_size;
}
}
if (self.dyld_stub_binder_index == null) {
self.dyld_stub_binder_index = @intCast(u16, self.undef_symbols.items.len);
const name = try self.makeString("dyld_stub_binder");
@ -1719,17 +1634,6 @@ fn findFreeSpace(self: *MachO, object_size: u64, min_alignment: u16) u64 {
return start;
}
fn writeSymbol(self: *MachO, index: usize) !void {
const tracy = trace(@src());
defer tracy.end();
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const sym = [1]macho.nlist_64{self.local_symbols.items[index]};
const off = symtab.symoff + @sizeOf(macho.nlist_64) * index;
log.debug("writing symbol {} at 0x{x}\n", .{ sym[0], off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(sym[0..1]), off);
}
fn writeOffsetTableEntry(self: *MachO, index: usize) !void {
const sect = &self.sections.items[self.got_section_index.?];
const endian = self.base.options.target.cpu.arch.endian();
@ -1740,30 +1644,72 @@ fn writeOffsetTableEntry(self: *MachO, index: usize) !void {
try self.base.file.?.pwriteAll(&buf, off);
}
fn writeAllGlobalSymbols(self: *MachO) !void {
fn writeSymbolTable(self: *MachO) !void {
// TODO workout how we can cache these so that we only overwrite symbols that were updated
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const off = symtab.symoff + self.local_symbols.items.len * @sizeOf(macho.nlist_64);
const file_size = self.global_symbols.items.len * @sizeOf(macho.nlist_64);
log.debug("writing global symbols from 0x{x} to 0x{x}\n", .{ off, file_size + off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.global_symbols.items), off);
const locals_off = self.linkedit_segment_next_offset.?;
const locals_size = self.local_symbols.items.len * @sizeOf(macho.nlist_64);
log.debug("writing local symbols from 0x{x} to 0x{x}\n", .{ locals_off, locals_size + locals_off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.local_symbols.items), locals_off);
const globals_off = locals_off + locals_size;
const globals_size = self.global_symbols.items.len * @sizeOf(macho.nlist_64);
log.debug("writing global symbols from 0x{x} to 0x{x}\n", .{ globals_off, globals_size + globals_off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.global_symbols.items), globals_off);
const undefs_off = globals_off + globals_size;
const undefs_size = self.undef_symbols.items.len * @sizeOf(macho.nlist_64);
log.debug("writing undef symbols from 0x{x} to 0x{x}\n", .{ undefs_off, undefs_size + undefs_off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.undef_symbols.items), undefs_off);
// Update symbol table.
const nlocals = @intCast(u32, self.local_symbols.items.len);
const nglobals = @intCast(u32, self.global_symbols.items.len);
const nundefs = @intCast(u32, self.undef_symbols.items.len);
symtab.symoff = self.linkedit_segment_next_offset.?;
symtab.nsyms = nlocals + nglobals + nundefs;
self.linkedit_segment_next_offset = symtab.symoff + symtab.nsyms * @sizeOf(macho.nlist_64);
// Update dynamic symbol table.
const dysymtab = &self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
dysymtab.nlocalsym = nlocals;
dysymtab.iextdefsym = nlocals;
dysymtab.nextdefsym = nglobals;
dysymtab.iundefsym = nlocals + nglobals;
dysymtab.nundefsym = nundefs;
// Advance size of __LINKEDIT segment
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
linkedit.filesize += symtab.nsyms * @sizeOf(macho.nlist_64);
if (linkedit.vmsize < linkedit.filesize) {
linkedit.vmsize = mem.alignForwardGeneric(u64, linkedit.filesize, self.page_size);
}
self.cmd_table_dirty = true;
}
fn writeAllUndefSymbols(self: *MachO) !void {
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const nlocals = self.local_symbols.items.len;
const nglobals = self.global_symbols.items.len;
const off = symtab.symoff + (nlocals + nglobals) * @sizeOf(macho.nlist_64);
const file_size = self.undef_symbols.items.len * @sizeOf(macho.nlist_64);
log.debug("writing undef symbols from 0x{x} to 0x{x}\n", .{ off, file_size + off });
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.undef_symbols.items), off);
fn writeCodeSignaturePadding(self: *MachO) !void {
const code_sig_cmd = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
const fileoff = self.linkedit_segment_next_offset.?;
const datasize: u32 = 0x1000; // TODO Calculate the expected size of the signature.
code_sig_cmd.dataoff = fileoff;
code_sig_cmd.datasize = datasize;
self.linkedit_segment_next_offset = fileoff + datasize;
// Advance size of __LINKEDIT segment
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
linkedit.filesize += datasize;
if (linkedit.vmsize < linkedit.filesize) {
linkedit.vmsize = mem.alignForwardGeneric(u64, linkedit.filesize, self.page_size);
}
log.debug("writing code signature padding from 0x{x} to 0x{x}\n", .{ fileoff, fileoff + datasize });
// Pad out the space. We need to do this to calculate valid hashes for everything in the file
// except for code signature data.
try self.base.file.?.pwriteAll(&[_]u8{0}, fileoff + datasize - 1);
}
fn writeCodeSignature(self: *MachO) !void {
const code_sig_cmd = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
// Pad out the space. We need to do this to calculate valid hashes for everything in the file
// except for code signature data.
try self.base.file.?.pwriteAll(&[_]u8{0}, code_sig_cmd.dataoff + code_sig_cmd.datasize - 1);
var code_sig = CodeSignature.init(self.base.allocator);
defer code_sig.deinit();
@ -1780,7 +1726,7 @@ fn writeCodeSignature(self: *MachO) !void {
}
fn writeExportTrie(self: *MachO) !void {
if (self.global_symbols.items.len == 0) return; // No exports, nothing to do.
assert(self.global_symbols.items.len > 0);
var trie: Trie = .{};
defer trie.deinit(self.base.allocator);
@ -1803,23 +1749,51 @@ fn writeExportTrie(self: *MachO) !void {
try trie.writeULEB128Mem(self.base.allocator, &buffer);
const dyld_info = &self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfo;
const export_size = @intCast(u32, mem.alignForward(buffer.items.len, @sizeOf(u64)));
dyld_info.export_off = self.linkedit_segment_next_offset.?;
dyld_info.export_size = export_size;
log.debug("writing export trie from 0x{x} to 0x{x}\n", .{ dyld_info.export_off, dyld_info.export_off + export_size });
if (export_size > buffer.items.len) {
// Pad out to align(8).
try self.base.file.?.pwriteAll(&[_]u8{ 0 }, dyld_info.export_off + export_size);
}
try self.base.file.?.pwriteAll(buffer.items, dyld_info.export_off);
self.linkedit_segment_next_offset = dyld_info.export_off + dyld_info.export_size;
// Advance size of __LINKEDIT segment
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
linkedit.filesize += dyld_info.export_size;
if (linkedit.vmsize < linkedit.filesize) {
linkedit.vmsize = mem.alignForwardGeneric(u64, linkedit.filesize, self.page_size);
}
self.cmd_table_dirty = true;
}
fn writeStringTable(self: *MachO) !void {
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const allocated_size = self.allocatedSize(symtab.stroff);
const needed_size = self.string_table.items.len;
if (needed_size > allocated_size) {
symtab.strsize = 0;
symtab.stroff = @intCast(u32, self.findFreeSpace(needed_size, 1));
}
symtab.strsize = @intCast(u32, needed_size);
symtab.stroff = self.linkedit_segment_next_offset.?;
symtab.strsize = @intCast(u32, mem.alignForward(needed_size, @sizeOf(u64)));
log.debug("writing string table from 0x{x} to 0x{x}\n", .{ symtab.stroff, symtab.stroff + symtab.strsize });
if (symtab.strsize > needed_size) {
// Pad out to align(8);
try self.base.file.?.pwriteAll(&[_]u8{ 0 }, symtab.stroff + symtab.strsize);
}
try self.base.file.?.pwriteAll(self.string_table.items, symtab.stroff);
self.linkedit_segment_next_offset = symtab.stroff + symtab.strsize;
// Advance size of __LINKEDIT segment
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
linkedit.filesize += symtab.strsize;
if (linkedit.vmsize < linkedit.filesize) {
linkedit.vmsize = mem.alignForwardGeneric(u64, linkedit.filesize, self.page_size);
}
self.cmd_table_dirty = true;
}
fn writeCmdHeaders(self: *MachO) !void {