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macho: deduplicate symbol table relocation codepath

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This commit is contained in:
Jakub Konka 2020-12-21 18:31:26 +01:00
parent a1b3606f0e
commit de5421a0a6
1 changed files with 11 additions and 31 deletions
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42
src/link/MachO.zig
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@ -1940,10 +1940,7 @@ fn writeOffsetTableEntry(self: *MachO, index: usize) !void {
try self.base.file.?.pwriteAll(&code, off);
}
fn writeLocalSymbol(self: *MachO, index: usize) !void {
const tracy = trace(@src());
defer tracy.end();
fn relocateSymbolTable(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;
@ -1972,7 +1969,13 @@ fn writeLocalSymbol(self: *MachO, index: usize) !void {
symtab.nsyms = @intCast(u32, nsyms);
self.cmd_table_dirty = true;
}
}
fn writeLocalSymbol(self: *MachO, index: usize) !void {
const tracy = trace(@src());
defer tracy.end();
try self.relocateSymbolTable();
const symtab = &self.load_commands.items[self.symtab_cmd_index.?].Symtab;
const off = symtab.symoff + @sizeOf(macho.nlist_64) * index;
log.debug("writing local symbol {} at 0x{x}", .{ index, off });
try self.base.file.?.pwriteAll(mem.asBytes(&self.local_symbols.items[index]), off);
@ -1982,45 +1985,22 @@ fn writeAllGlobalAndUndefSymbols(self: *MachO) !void {
const tracy = trace(@src());
defer tracy.end();
try self.relocateSymbolTable();
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 nundefs = self.undef_symbols.items.len;
const nsyms = nlocals + nglobals + nundefs;
if (symtab.nsyms < nsyms) {
const linkedit_segment = self.load_commands.items[self.linkedit_segment_cmd_index.?].Segment;
const needed_size = nsyms * @sizeOf(macho.nlist_64);
if (needed_size > self.allocatedSize(&linkedit_segment, symtab.symoff)) {
// Move the entire symbol table to a new location
const new_symoff = self.findFreeSpace(&linkedit_segment, needed_size, @alignOf(macho.nlist_64));
const existing_size = symtab.nsyms * @sizeOf(macho.nlist_64);
log.debug("relocating symbol table from 0x{x}-0x{x} to 0x{x}-0x{x}", .{
symtab.symoff,
symtab.symoff + existing_size,
new_symoff,
new_symoff + existing_size,
});
const amt = try self.base.file.?.copyRangeAll(symtab.symoff, self.base.file.?, new_symoff, existing_size);
if (amt != existing_size) return error.InputOutput;
symtab.symoff = @intCast(u32, new_symoff);
}
symtab.nsyms = @intCast(u32, nsyms);
self.cmd_table_dirty = true;
}
const locals_off = symtab.symoff;
const locals_size = self.local_symbols.items.len * @sizeOf(macho.nlist_64);
const locals_size = nlocals * @sizeOf(macho.nlist_64);
const globals_off = locals_off + locals_size;
const globals_size = self.global_symbols.items.len * @sizeOf(macho.nlist_64);
const globals_size = nglobals * @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);
const undefs_size = nundefs * @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);