Dwarf: Added stroffsetsptr support (#12270)

* Added support for stroffsetsptr class in Dwarf stdlib

* Proper initializion of debug_str_offsets in DwarfInfo

* Added missing null initializer to DwarfInfo in Macho

* Added missing is_64 field to getAttrString in DwarfInfo

* Fixed formatting

* Added missing is_64 param to getAttrString

* Added required cast to usize

* Adding missing .debug_str_offsets initialization

* getAttrString now uses the str_offsets_base attr

2 files changed, 35 insertions, 4 deletions

diff --git a/lib/std/debug.zig b/lib/std/debug.zig
index 33b8a98d7f..3ce9f3c1d3 100644
--- a/lib/std/debug.zig
+++ b/lib/std/debug.zig
@@ -846,6 +846,7 @@ fn readCoffDebugInfo(allocator: mem.Allocator, coff_file: File) !ModuleDebugInfo
                 .debug_info = debug_info_data orelse return error.MissingDebugInfo,
                 .debug_abbrev = debug_abbrev_data orelse return error.MissingDebugInfo,
                 .debug_str = debug_str_data orelse return error.MissingDebugInfo,
+                .debug_str_offsets = null,
                 .debug_line = debug_line_data orelse return error.MissingDebugInfo,
                 .debug_line_str = debug_line_str_data,
                 .debug_ranges = debug_ranges_data,
@@ -912,6 +913,7 @@ pub fn readElfDebugInfo(allocator: mem.Allocator, elf_file: File) !ModuleDebugIn
         var opt_debug_info: ?[]const u8 = null;
         var opt_debug_abbrev: ?[]const u8 = null;
         var opt_debug_str: ?[]const u8 = null;
+        var opt_debug_str_offsets: ?[]const u8 = null;
         var opt_debug_line: ?[]const u8 = null;
         var opt_debug_line_str: ?[]const u8 = null;
         var opt_debug_ranges: ?[]const u8 = null;
@@ -926,6 +928,8 @@ pub fn readElfDebugInfo(allocator: mem.Allocator, elf_file: File) !ModuleDebugIn
                 opt_debug_abbrev = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
             } else if (mem.eql(u8, name, ".debug_str")) {
                 opt_debug_str = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
+            } else if (mem.eql(u8, name, ".debug_str_offsets")) {
+                opt_debug_str_offsets = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
             } else if (mem.eql(u8, name, ".debug_line")) {
                 opt_debug_line = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
             } else if (mem.eql(u8, name, ".debug_line_str")) {
@@ -940,6 +944,7 @@ pub fn readElfDebugInfo(allocator: mem.Allocator, elf_file: File) !ModuleDebugIn
             .debug_info = opt_debug_info orelse return error.MissingDebugInfo,
             .debug_abbrev = opt_debug_abbrev orelse return error.MissingDebugInfo,
             .debug_str = opt_debug_str orelse return error.MissingDebugInfo,
+            .debug_str_offsets = opt_debug_str_offsets,
             .debug_line = opt_debug_line orelse return error.MissingDebugInfo,
             .debug_line_str = opt_debug_line_str,
             .debug_ranges = opt_debug_ranges,
@@ -1515,6 +1520,7 @@ pub const ModuleDebugInfo = switch (native_os) {
                 .debug_info = try chopSlice(mapped_mem, debug_info.offset, debug_info.size),
                 .debug_abbrev = try chopSlice(mapped_mem, debug_abbrev.offset, debug_abbrev.size),
                 .debug_str = try chopSlice(mapped_mem, debug_str.offset, debug_str.size),
+                .debug_str_offsets = null,
                 .debug_line = try chopSlice(mapped_mem, debug_line.offset, debug_line.size),
                 .debug_line_str = if (opt_debug_line_str) |debug_line_str|
                     try chopSlice(mapped_mem, debug_line_str.offset, debug_line_str.size)
@@ -1578,6 +1584,7 @@ pub const ModuleDebugInfo = switch (native_os) {
                         .compile_unit_name = compile_unit.die.getAttrString(
                             o_file_di,
                             DW.AT.name,
+                            compile_unit.is_64,
                         ) catch |err| switch (err) {
                             error.MissingDebugInfo, error.InvalidDebugInfo => "???",
                         },
@@ -1698,7 +1705,7 @@ fn getSymbolFromDwarf(allocator: mem.Allocator, address: u64, di: *DW.DwarfInfo)
     if (nosuspend di.findCompileUnit(address)) |compile_unit| {
         return SymbolInfo{
             .symbol_name = nosuspend di.getSymbolName(address) orelse "???",
-            .compile_unit_name = compile_unit.die.getAttrString(di, DW.AT.name) catch |err| switch (err) {
+            .compile_unit_name = compile_unit.die.getAttrString(di, DW.AT.name, compile_unit.is_64) catch |err| switch (err) {
                 error.MissingDebugInfo, error.InvalidDebugInfo => "???",
             },
             .line_info = nosuspend di.getLineNumberInfo(allocator, compile_unit.*, address) catch |err| switch (err) {
diff --git a/lib/std/dwarf.zig b/lib/std/dwarf.zig
index d61d198c7e..40dfc8cebb 100644
--- a/lib/std/dwarf.zig
+++ b/lib/std/dwarf.zig
@@ -214,6 +214,7 @@ const FormValue = union(enum) {
     RefAddr: u64,
     String: []const u8,
     StrPtr: u64,
+    StrOffset: u64,
     LineStrPtr: u64,
 };
 
@@ -284,11 +285,15 @@ const Die = struct {
         };
     }
 
-    pub fn getAttrString(self: *const Die, di: *DwarfInfo, id: u64) ![]const u8 {
+    pub fn getAttrString(self: *const Die, di: *DwarfInfo, id: u64, is_64: bool) ![]const u8 {
         const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
         return switch (form_value.*) {
             FormValue.String => |value| value,
             FormValue.StrPtr => |offset| di.getString(offset),
+            FormValue.StrOffset => |index| blk: {
+                const base_offset = self.getAttrSecOffset(AT.str_offsets_base) catch 0;
+                break :blk di.getLineString(try di.getStringOffset(base_offset + index, is_64));
+            },
             FormValue.LineStrPtr => |offset| di.getLineString(offset),
             else => error.InvalidDebugInfo,
         };
@@ -522,6 +527,10 @@ fn parseFormValue(allocator: mem.Allocator, in_stream: anytype, form_id: u64, en
 
         FORM.string => FormValue{ .String = try in_stream.readUntilDelimiterAlloc(allocator, 0, math.maxInt(usize)) },
         FORM.strp => FormValue{ .StrPtr = try readAddress(in_stream, endian, is_64) },
+        FORM.strx1 => return FormValue{ .StrOffset = @intCast(u64, try in_stream.readInt(u8, endian)) },
+        FORM.strx2 => return FormValue{ .StrOffset = @intCast(u64, try in_stream.readInt(u16, endian)) },
+        FORM.strx3 => return FormValue{ .StrOffset = @intCast(u64, try in_stream.readInt(u24, endian)) },
+        FORM.strx4 => return FormValue{ .StrOffset = @intCast(u64, try in_stream.readInt(u32, endian)) },
         FORM.line_strp => FormValue{ .LineStrPtr = try readAddress(in_stream, endian, is_64) },
         FORM.indirect => {
             const child_form_id = try nosuspend leb.readULEB128(u64, in_stream);
@@ -554,6 +563,7 @@ pub const DwarfInfo = struct {
     debug_info: []const u8,
     debug_abbrev: []const u8,
     debug_str: []const u8,
+    debug_str_offsets: ?[]const u8,
     debug_line: []const u8,
     debug_line_str: ?[]const u8,
     debug_ranges: ?[]const u8,
@@ -652,7 +662,7 @@ pub const DwarfInfo = struct {
                             // Prevent endless loops
                             while (depth > 0) : (depth -= 1) {
                                 if (this_die_obj.getAttr(AT.name)) |_| {
-                                    const name = try this_die_obj.getAttrString(di, AT.name);
+                                    const name = try this_die_obj.getAttrString(di, AT.name, is_64);
                                     break :x try allocator.dupe(u8, name);
                                 } else if (this_die_obj.getAttr(AT.abstract_origin)) |_| {
                                     // Follow the DIE it points to and repeat
@@ -956,7 +966,7 @@ pub const DwarfInfo = struct {
         const in = &stream.reader();
         const seekable = &stream.seekableStream();
 
-        const compile_unit_cwd = try compile_unit.die.getAttrString(di, AT.comp_dir);
+        const compile_unit_cwd = try compile_unit.die.getAttrString(di, AT.comp_dir, compile_unit.is_64);
         const line_info_offset = try compile_unit.die.getAttrSecOffset(AT.stmt_list);
 
         try seekable.seekTo(line_info_offset);
@@ -1144,6 +1154,20 @@ pub const DwarfInfo = struct {
         return error.InvalidDebugInfo;
     }
 
+    fn getStringOffset(di: *DwarfInfo, offset: u64, is_64: bool) !u64 {
+        if (di.debug_str_offsets) |debug_str_offsets| {
+            if (offset >= debug_str_offsets.len) {
+                return error.InvalidDebugInfo;
+            }
+            const offset_casted = @intCast(usize, offset);
+            if (is_64) {
+                return std.mem.readIntSlice(u64, debug_str_offsets[offset_casted .. offset_casted + 8], di.endian);
+            }
+            return @intCast(u64, std.mem.readIntSlice(u32, debug_str_offsets[offset_casted .. offset_casted + 4], di.endian));
+        }
+        return error.InvalidDebugInfo;
+    }
+
     fn getLineString(di: *DwarfInfo, offset: u64) ![]const u8 {
         const debug_line_str = di.debug_line_str orelse return error.InvalidDebugInfo;
         if (offset > debug_line_str.len)