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Merge pull request #20997 from xxxbxxx/debuglink

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std.debug.Dwarf: improve loading debug symbol from separate files
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Andrew Kelley 2024-08-08 11:06:14 -07:00 committed by GitHub
commit 8031251c33
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2 changed files with 81 additions and 21 deletions
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87
lib/std/debug/Dwarf.zig
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@ -239,7 +239,7 @@ pub const Die = struct {
return switch (form_value.*) {
.addr => |value| value,
.addrx => |index| di.readDebugAddr(compile_unit, index),
else => error.InvalidDebugInfo,
else => bad(),
};
}
@ -252,7 +252,7 @@ pub const Die = struct {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return switch (form_value.*) {
.Const => |value| value.asUnsignedLe(),
else => error.InvalidDebugInfo,
else => bad(),
};
}
@ -260,7 +260,7 @@ pub const Die = struct {
const form_value = self.getAttr(id) orelse return error.MissingDebugInfo;
return switch (form_value.*) {
.ref => |value| value,
else => error.InvalidDebugInfo,
else => bad(),
};
}
@ -2159,7 +2159,7 @@ pub const ElfModule = struct {
if (mem.eql(u8, name, ".gnu_debuglink")) {
const gnu_debuglink = try chopSlice(mapped_mem, shdr.sh_offset, shdr.sh_size);
const debug_filename = mem.sliceTo(@as([*:0]const u8, @ptrCast(gnu_debuglink.ptr)), 0);
const crc_offset = mem.alignForward(usize, @intFromPtr(&debug_filename[debug_filename.len]) + 1, 4) - @intFromPtr(gnu_debuglink.ptr);
const crc_offset = mem.alignForward(usize, debug_filename.len + 1, 4);
const crc_bytes = gnu_debuglink[crc_offset..][0..4];
separate_debug_crc = mem.readInt(u32, crc_bytes, native_endian);
separate_debug_filename = debug_filename;
@ -2215,6 +2215,46 @@ pub const ElfModule = struct {
return error.MissingDebugInfo;
}
// $XDG_CACHE_HOME/debuginfod_client/<buildid>/debuginfo
// This only opportunisticly tries to load from the debuginfod cache, but doesn't try to populate it.
// One can manually run `debuginfod-find debuginfo PATH` to download the symbols
if (build_id) |id| blk: {
var debuginfod_dir: std.fs.Dir = switch (builtin.os.tag) {
.wasi, .windows => break :blk,
else => dir: {
if (std.posix.getenv("DEBUGINFOD_CACHE_PATH")) |path| {
break :dir std.fs.openDirAbsolute(path, .{}) catch break :blk;
}
if (std.posix.getenv("XDG_CACHE_HOME")) |cache_path| {
const path = std.fs.path.join(gpa, &[_][]const u8{ cache_path, "debuginfod_client" }) catch break :blk;
defer gpa.free(path);
break :dir std.fs.openDirAbsolute(path, .{}) catch break :blk;
}
if (std.posix.getenv("HOME")) |home_path| {
const path = std.fs.path.join(gpa, &[_][]const u8{ home_path, ".cache", "debuginfod_client" }) catch break :blk;
defer gpa.free(path);
break :dir std.fs.openDirAbsolute(path, .{}) catch break :blk;
}
break :blk;
},
};
defer debuginfod_dir.close();
const filename = std.fmt.allocPrint(
gpa,
"{s}/debuginfo",
.{std.fmt.fmtSliceHexLower(id)},
) catch break :blk;
defer gpa.free(filename);
const path: Path = .{
.root_dir = .{ .path = null, .handle = debuginfod_dir },
.sub_path = filename,
};
return loadPath(gpa, path, null, separate_debug_crc, &sections, mapped_mem) catch break :blk;
}
const global_debug_directories = [_][]const u8{
"/usr/lib/debug",
};
@ -2253,25 +2293,30 @@ pub const ElfModule = struct {
if (elf_filename != null and mem.eql(u8, elf_filename.?, separate_filename))
return error.MissingDebugInfo;
// <cwd>/<gnu_debuglink>
if (loadPath(
gpa,
.{
.root_dir = std.Build.Cache.Directory.cwd(),
.sub_path = separate_filename,
},
null,
separate_debug_crc,
&sections,
mapped_mem,
)) |debug_info| {
return debug_info;
} else |_| {}
exe_dir: {
var exe_dir_buf: [std.fs.max_path_bytes]u8 = undefined;
const exe_dir_path = std.fs.selfExeDirPath(&exe_dir_buf) catch break :exe_dir;
var exe_dir = std.fs.openDirAbsolute(exe_dir_path, .{}) catch break :exe_dir;
defer exe_dir.close();
// <cwd>/.debug/<gnu_debuglink>
{
// <exe_dir>/<gnu_debuglink>
if (loadPath(
gpa,
.{
.root_dir = .{ .path = null, .handle = exe_dir },
.sub_path = separate_filename,
},
null,
separate_debug_crc,
&sections,
mapped_mem,
)) |debug_info| {
return debug_info;
} else |_| {}
// <exe_dir>/.debug/<gnu_debuglink>
const path: Path = .{
.root_dir = std.Build.Cache.Directory.cwd(),
.root_dir = .{ .path = null, .handle = exe_dir },
.sub_path = try std.fs.path.join(gpa, &.{ ".debug", separate_filename }),
};
defer gpa.free(path.sub_path);

15
test/standalone/stack_iterator/build.zig
View File

@ -93,6 +93,21 @@ pub fn build(b: *std.Build) void {
const run_cmd = b.addRunArtifact(exe);
test_step.dependOn(&run_cmd.step);
// Separate debug info ELF file
if (target.result.ofmt == .elf) {
const filename = b.fmt("{s}_stripped", .{exe.out_filename});
const stripped_exe = b.addObjCopy(exe.getEmittedBin(), .{
.basename = filename, // set the name for the debuglink
.compress_debug = true,
.strip = .debug,
.extract_to_separate_file = true,
});
const run_stripped = std.Build.Step.Run.create(b, b.fmt("run {s}", .{filename}));
run_stripped.addFileArg(stripped_exe.getOutput());
test_step.dependOn(&run_stripped.step);
}
}
// Unwinding without libc/posix