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macho: parse symbol and string tables

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This commit is contained in:
Jakub Konka 2020-12-11 18:24:07 +01:00
parent f5a0b9315b
commit b099fdff93
1 changed files with 41 additions and 2 deletions
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43
src/link/MachO.zig
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@ -801,6 +801,16 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
mem.copy(u8, dylib_cmd.data, mem.spanZ(LIB_SYSTEM_PATH));
try self.load_commands.append(self.base.allocator, .{ .Dylib = dylib_cmd });
if (self.symtab_cmd_index == null or self.dysymtab_cmd_index == null) {
std.log.err("Incomplete Mach-O binary: no LC_SYMTAB or LC_DYSYMTAB load command found!", .{});
std.log.err("Without the symbol table, it is not possible to patch up the binary for cross-compilation.", .{});
return error.NoSymbolTable;
}
// Parse symbol and string tables.
try self.parseSymbolTable();
try self.parseStringTable();
// Parse dyld info
try self.parseBindingInfo();
try self.parseLazyBindingInfo();
@ -2038,8 +2048,6 @@ fn parseFromFile(self: *MachO, file: fs.File) !void {
self.load_commands.appendAssumeCapacity(cmd);
}
self.header = header;
// TODO Should we parse memory mapped segments here or as needed?
}
fn parseAndCmpName(name: []const u8, needle: []const u8) bool {
@ -2047,6 +2055,37 @@ fn parseAndCmpName(name: []const u8, needle: []const u8) bool {
return mem.eql(u8, name[0..len], needle);
}
fn parseSymbolTable(self: *MachO) !void {
const symtab = self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const dysymtab = self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
var buffer = try self.base.allocator.alloc(macho.nlist_64, symtab.nsyms);
defer self.base.allocator.free(buffer);
const nread = try self.base.file.?.preadAll(@ptrCast([*]u8, buffer)[0 .. symtab.nsyms * @sizeOf(macho.nlist_64)], symtab.symoff);
assert(@divExact(nread, @sizeOf(macho.nlist_64)) == buffer.len);
try self.local_symbols.ensureCapacity(self.base.allocator, dysymtab.nlocalsym);
try self.global_symbols.ensureCapacity(self.base.allocator, dysymtab.nextdefsym);
try self.undef_symbols.ensureCapacity(self.base.allocator, dysymtab.nundefsym);
self.local_symbols.appendSliceAssumeCapacity(buffer[dysymtab.ilocalsym .. dysymtab.ilocalsym + dysymtab.nlocalsym]);
self.global_symbols.appendSliceAssumeCapacity(buffer[dysymtab.iextdefsym .. dysymtab.iextdefsym + dysymtab.nextdefsym]);
self.undef_symbols.appendSliceAssumeCapacity(buffer[dysymtab.iundefsym .. dysymtab.iundefsym + dysymtab.nundefsym]);
}
fn parseStringTable(self: *MachO) !void {
const symtab = self.load_commands.items[self.symtab_cmd_index.?].Symtab;
var buffer = try self.base.allocator.alloc(u8, symtab.strsize);
defer self.base.allocator.free(buffer);
const nread = try self.base.file.?.preadAll(buffer, symtab.stroff);
assert(nread == buffer.len);
try self.string_table.ensureCapacity(self.base.allocator, symtab.strsize);
self.string_table.appendSliceAssumeCapacity(buffer);
}
fn parseBindingInfo(self: *MachO) !void {
const dyld_info = self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfoOnly;
var buffer = try self.base.allocator.alloc(u8, dyld_info.bind_size);