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coff: improve default COFF/PE object parser

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We now do not allocate memory for headers and other metadata unless
requested by the caller. Instead, we read-in the entire contents
of the image into memory and operate on pointers and casts wherever
possible. I have a left a TODO to hook up Windows' memory-mapped API
here in-place of standard `readToEndAlloc` which should be more memory
proof on memory constrained hosts.

This commit also supplements our `std.coff` with a lot missing basic
extern structs required to make our COFF linker.
This commit is contained in:
Jakub Konka 2022-08-22 19:48:14 +02:00
parent 9043e665a5
commit c84e5ee878
3 changed files with 1025 additions and 286 deletions
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1242
lib/std/coff.zig
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File diff suppressed because it is too large Load Diff

40
lib/std/debug.zig
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@ -816,11 +816,11 @@ pub fn openSelfDebugInfo(allocator: mem.Allocator) anyerror!DebugInfo {
/// TODO it's weird to take ownership even on error, rework this code.
fn readCoffDebugInfo(allocator: mem.Allocator, coff_file: File) !ModuleDebugInfo {
nosuspend {
errdefer coff_file.close();
defer coff_file.close();
const coff_obj = try allocator.create(coff.Coff);
errdefer allocator.destroy(coff_obj);
coff_obj.* = coff.Coff.init(allocator, coff_file);
coff_obj.* = .{ .allocator = allocator };
var di = ModuleDebugInfo{
.base_address = undefined,
@ -828,18 +828,21 @@ fn readCoffDebugInfo(allocator: mem.Allocator, coff_file: File) !ModuleDebugInfo
.debug_data = undefined,
};
try di.coff.loadHeader();
try di.coff.loadSections();
if (di.coff.getSection(".debug_info")) |sec| {
// TODO convert to Windows' memory-mapped file API
const file_len = math.cast(usize, try coff_file.getEndPos()) orelse math.maxInt(usize);
const data = try coff_file.readToEndAlloc(allocator, file_len);
try di.coff.parse(data);
if (di.coff.getSectionByName(".debug_info")) |sec| {
// This coff file has embedded DWARF debug info
_ = sec;
// TODO: free the section data slices
const debug_info_data = di.coff.getSectionData(".debug_info", allocator) catch null;
const debug_abbrev_data = di.coff.getSectionData(".debug_abbrev", allocator) catch null;
const debug_str_data = di.coff.getSectionData(".debug_str", allocator) catch null;
const debug_line_data = di.coff.getSectionData(".debug_line", allocator) catch null;
const debug_line_str_data = di.coff.getSectionData(".debug_line_str", allocator) catch null;
const debug_ranges_data = di.coff.getSectionData(".debug_ranges", allocator) catch null;
const debug_info_data = di.coff.getSectionDataAlloc(".debug_info", allocator) catch null;
const debug_abbrev_data = di.coff.getSectionDataAlloc(".debug_abbrev", allocator) catch null;
const debug_str_data = di.coff.getSectionDataAlloc(".debug_str", allocator) catch null;
const debug_line_data = di.coff.getSectionDataAlloc(".debug_line", allocator) catch null;
const debug_line_str_data = di.coff.getSectionDataAlloc(".debug_line_str", allocator) catch null;
const debug_ranges_data = di.coff.getSectionDataAlloc(".debug_ranges", allocator) catch null;
var dwarf = DW.DwarfInfo{
.endian = native_endian,
@ -1628,7 +1631,7 @@ pub const ModuleDebugInfo = switch (native_os) {
switch (self.debug_data) {
.dwarf => |*dwarf| {
const dwarf_address = relocated_address + self.coff.pe_header.image_base;
const dwarf_address = relocated_address + self.coff.getImageBase();
return getSymbolFromDwarf(allocator, dwarf_address, dwarf);
},
.pdb => {
@ -1636,13 +1639,14 @@ pub const ModuleDebugInfo = switch (native_os) {
},
}
var coff_section: *coff.Section = undefined;
var coff_section: *align(1) const coff.SectionHeader = undefined;
const mod_index = for (self.debug_data.pdb.sect_contribs) |sect_contrib| {
if (sect_contrib.Section > self.coff.sections.items.len) continue;
const sections = self.coff.getSectionHeaders();
if (sect_contrib.Section > sections.len) continue;
// Remember that SectionContribEntry.Section is 1-based.
coff_section = &self.coff.sections.items[sect_contrib.Section - 1];
coff_section = &sections[sect_contrib.Section - 1];
const vaddr_start = coff_section.header.virtual_address + sect_contrib.Offset;
const vaddr_start = coff_section.virtual_address + sect_contrib.Offset;
const vaddr_end = vaddr_start + sect_contrib.Size;
if (relocated_address >= vaddr_start and relocated_address < vaddr_end) {
break sect_contrib.ModuleIndex;
@ -1658,11 +1662,11 @@ pub const ModuleDebugInfo = switch (native_os) {
const symbol_name = self.debug_data.pdb.getSymbolName(
module,
relocated_address - coff_section.header.virtual_address,
relocated_address - coff_section.virtual_address,
) orelse "???";
const opt_line_info = try self.debug_data.pdb.getLineNumberInfo(
module,
relocated_address - coff_section.header.virtual_address,
relocated_address - coff_section.virtual_address,
);
return SymbolInfo{

29
src/link/Coff.zig
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@ -204,15 +204,18 @@ pub fn openPath(allocator: Allocator, sub_path: []const u8, options: link.Option
index += 2;
// Characteristics
var characteristics: u16 = std.coff.IMAGE_FILE_DEBUG_STRIPPED | std.coff.IMAGE_FILE_RELOCS_STRIPPED; // TODO Remove debug info stripped flag when necessary
var characteristics: std.coff.CoffHeaderFlags = .{
.DEBUG_STRIPPED = 1, // TODO remove debug info stripped flag when necessary
.RELOCS_STRIPPED = 1,
};
if (options.output_mode == .Exe) {
characteristics |= std.coff.IMAGE_FILE_EXECUTABLE_IMAGE;
characteristics.EXECUTABLE_IMAGE = 1;
}
switch (self.ptr_width) {
.p32 => characteristics |= std.coff.IMAGE_FILE_32BIT_MACHINE,
.p64 => characteristics |= std.coff.IMAGE_FILE_LARGE_ADDRESS_AWARE,
.p32 => characteristics.@"32BIT_MACHINE" = 1,
.p64 => characteristics.LARGE_ADDRESS_AWARE = 1,
}
mem.writeIntLittle(u16, hdr_data[index..][0..2], characteristics);
mem.writeIntLittle(u16, hdr_data[index..][0..2], @bitCast(u16, characteristics));
index += 2;
assert(index == 20);
@ -352,7 +355,10 @@ pub fn openPath(allocator: Allocator, sub_path: []const u8, options: link.Option
mem.set(u8, hdr_data[index..][0..12], 0);
index += 12;
// Section flags
mem.writeIntLittle(u32, hdr_data[index..][0..4], std.coff.IMAGE_SCN_CNT_INITIALIZED_DATA | std.coff.IMAGE_SCN_MEM_READ);
mem.writeIntLittle(u32, hdr_data[index..][0..4], @bitCast(u32, std.coff.SectionHeaderFlags{
.CNT_INITIALIZED_DATA = 1,
.MEM_READ = 1,
}));
index += 4;
// Then, the .text section
hdr_data[index..][0..8].* = ".text\x00\x00\x00".*;
@ -378,11 +384,12 @@ pub fn openPath(allocator: Allocator, sub_path: []const u8, options: link.Option
mem.set(u8, hdr_data[index..][0..12], 0);
index += 12;
// Section flags
mem.writeIntLittle(
u32,
hdr_data[index..][0..4],
std.coff.IMAGE_SCN_CNT_CODE | std.coff.IMAGE_SCN_MEM_EXECUTE | std.coff.IMAGE_SCN_MEM_READ | std.coff.IMAGE_SCN_MEM_WRITE,
);
mem.writeIntLittle(u32, hdr_data[index..][0..4], @bitCast(u32, std.coff.SectionHeaderFlags{
.CNT_CODE = 1,
.MEM_EXECUTE = 1,
.MEM_READ = 1,
.MEM_WRITE = 1,
}));
index += 4;
assert(index == optional_header_size + section_table_size);