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stage2 macho: preallocate empty code sig space

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This commit is contained in:
Jakub Konka 2020-11-19 18:52:48 +01:00
parent bbc4ee3f17
commit 403dc50ff7
1 changed files with 43 additions and 5 deletions
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48
src/link/MachO.zig
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@ -110,6 +110,8 @@ main_cmd_index: ?u16 = null,
version_min_cmd_index: ?u16 = null,
/// Source version
source_version_cmd_index: ?u16 = null,
/// Code signature
code_signature_cmd_index: ?u16 = null,
/// Table of all sections
sections: std.ArrayListUnmanaged(macho.section_64) = .{},
@ -401,6 +403,15 @@ pub fn flushModule(self: *MachO, comp: *Compilation) !void {
// TODO remove when we add our own codesigning mechanism
try self.writeStringTable();
try self.codeSign();
{
// TODO rework how we preallocate space for the entire __LINKEDIT segment instead of
// doing dynamic updates like this.
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;
}
if (self.cmd_table_dirty) {
try self.writeCmdHeaders();
@ -1413,6 +1424,17 @@ pub fn populateMissingMetadata(self: *MachO) !void {
},
});
}
if (self.code_signature_cmd_index == null) {
self.code_signature_cmd_index = @intCast(u16, self.load_commands.items.len);
try self.load_commands.append(self.base.allocator, .{
.LinkeditData = .{
.cmd = macho.LC_CODE_SIGNATURE,
.cmdsize = @sizeOf(macho.linkedit_data_command),
.dataoff = 0,
.datasize = 0,
},
});
}
{
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;
@ -1458,6 +1480,17 @@ pub fn populateMissingMetadata(self: *MachO) !void {
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;
}
}
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");
@ -1722,6 +1755,16 @@ fn writeAllUndefSymbols(self: *MachO) !void {
try self.base.file.?.pwriteAll(mem.sliceAsBytes(self.undef_symbols.items), off);
}
fn codeSign(self: *MachO) !void {
const code_sig_cmd = &self.load_commands.items[self.code_signature_cmd_index.?].LinkeditData;
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const off = mem.alignForwardGeneric(u32, symtab.stroff + symtab.strsize, @sizeOf(u64));
symtab.strsize = off - symtab.stroff;
code_sig_cmd.dataoff = off;
// TODO add actual code signing mechanism
try self.base.file.?.pwriteAll(&[_]u8{ 0 }, code_sig_cmd.dataoff + code_sig_cmd.datasize - 1);
}
fn writeExportTrie(self: *MachO) !void {
if (self.global_symbols.items.len == 0) return; // No exports, nothing to do.
@ -1763,11 +1806,6 @@ fn writeStringTable(self: *MachO) !void {
log.debug("writing string table from 0x{x} to 0x{x}\n", .{ symtab.stroff, symtab.stroff + symtab.strsize });
try self.base.file.?.pwriteAll(self.string_table.items, symtab.stroff);
// TODO rework how we preallocate space for the entire __LINKEDIT segment instead of
// doing dynamic updates like this.
const linkedit = &self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
linkedit.filesize = symtab.stroff + symtab.strsize - linkedit.fileoff;
}
fn writeCmdHeaders(self: *MachO) !void {