diff options
Diffstat (limited to 'lib/std/debug/Dwarf/ElfModule.zig')
| -rw-r--r-- | lib/std/debug/Dwarf/ElfModule.zig | 376 |
1 files changed, 0 insertions, 376 deletions
diff --git a/lib/std/debug/Dwarf/ElfModule.zig b/lib/std/debug/Dwarf/ElfModule.zig deleted file mode 100644 index 4d425b1718..0000000000 --- a/lib/std/debug/Dwarf/ElfModule.zig +++ /dev/null @@ -1,376 +0,0 @@ -//! A thin wrapper around `Dwarf` which handles loading debug information from an ELF file. Load the -//! info with `load`, then directly access the `dwarf` field before finally `deinit`ing. - -dwarf: Dwarf, - -/// If we encounter a `.eh_frame` section while loading the ELF module, it is stored here and may be -/// used with `Dwarf.Unwind` for call stack unwinding. -eh_frame: ?UnwindSection, -/// If we encounter a `.debug_frame` section while loading the ELF module, it is stored here and may -/// be used with `Dwarf.Unwind` for call stack unwinding. -debug_frame: ?UnwindSection, - -/// The memory-mapped ELF file, which is referenced by `dwarf`. This field is here only so that -/// this memory can be unmapped by `ElfModule.deinit`. -mapped_file: []align(std.heap.page_size_min) const u8, -/// Sometimes, debug info is stored separately to the main ELF file. In that case, `mapped_file` -/// is the mapped ELF binary, and `mapped_debug_file` is the mapped debug info file. Both must -/// be unmapped by `ElfModule.deinit`. -mapped_debug_file: ?[]align(std.heap.page_size_min) const u8, - -pub const UnwindSection = struct { - vaddr: u64, - bytes: []const u8, - owned: bool, -}; - -pub fn deinit(em: *ElfModule, gpa: Allocator) void { - em.dwarf.deinit(gpa); - std.posix.munmap(em.mapped_file); - if (em.mapped_debug_file) |m| std.posix.munmap(m); - if (em.eh_frame) |s| if (s.owned) gpa.free(s.bytes); - if (em.debug_frame) |s| if (s.owned) gpa.free(s.bytes); -} - -pub const LoadError = error{ - InvalidDebugInfo, - MissingDebugInfo, - InvalidElfMagic, - InvalidElfVersion, - InvalidElfEndian, - /// TODO: implement this and then remove this error code - UnimplementedDwarfForeignEndian, - /// The debug info may be valid but this implementation uses memory - /// mapping which limits things to usize. If the target debug info is - /// 64-bit and host is 32-bit, there may be debug info that is not - /// supportable using this method. - Overflow, - - PermissionDenied, - LockedMemoryLimitExceeded, - MemoryMappingNotSupported, -} || Allocator.Error || std.fs.File.OpenError || Dwarf.OpenError; - -/// Reads debug info from an ELF file given its path. -/// -/// If the required sections aren't present but a reference to external debug -/// info is, then this this function will recurse to attempt to load the debug -/// sections from an external file. -pub fn load( - gpa: Allocator, - elf_file_path: Path, - build_id: ?[]const u8, - expected_crc: ?u32, - parent_sections: ?*Dwarf.SectionArray, - parent_mapped_mem: ?[]align(std.heap.page_size_min) const u8, -) LoadError!ElfModule { - const mapped_mem: []align(std.heap.page_size_min) const u8 = mapped: { - const elf_file = try elf_file_path.root_dir.handle.openFile(elf_file_path.sub_path, .{}); - defer elf_file.close(); - - const file_len = std.math.cast( - usize, - elf_file.getEndPos() catch return Dwarf.bad(), - ) orelse return error.Overflow; - - break :mapped std.posix.mmap( - null, - file_len, - std.posix.PROT.READ, - .{ .TYPE = .SHARED }, - elf_file.handle, - 0, - ) catch |err| switch (err) { - error.MappingAlreadyExists => unreachable, - else => |e| return e, - }; - }; - errdefer std.posix.munmap(mapped_mem); - - if (expected_crc) |crc| if (crc != std.hash.crc.Crc32.hash(mapped_mem)) return error.InvalidDebugInfo; - - const hdr: *const elf.Ehdr = @ptrCast(&mapped_mem[0]); - if (!mem.eql(u8, hdr.e_ident[0..4], elf.MAGIC)) return error.InvalidElfMagic; - if (hdr.e_ident[elf.EI_VERSION] != 1) return error.InvalidElfVersion; - - const endian: std.builtin.Endian = switch (hdr.e_ident[elf.EI_DATA]) { - elf.ELFDATA2LSB => .little, - elf.ELFDATA2MSB => .big, - else => return error.InvalidElfEndian, - }; - if (endian != native_endian) return error.UnimplementedDwarfForeignEndian; - - const shoff = hdr.e_shoff; - const str_section_off = std.math.cast( - usize, - shoff + @as(u64, hdr.e_shentsize) * @as(u64, hdr.e_shstrndx), - ) orelse return error.Overflow; - const str_shdr: *const elf.Shdr = @ptrCast(@alignCast(mapped_mem[str_section_off..])); - const header_strings = mapped_mem[str_shdr.sh_offset..][0..str_shdr.sh_size]; - const shdrs = @as( - [*]const elf.Shdr, - @ptrCast(@alignCast(&mapped_mem[shoff])), - )[0..hdr.e_shnum]; - - var sections: Dwarf.SectionArray = @splat(null); - // Combine section list. This takes ownership over any owned sections from the parent scope. - if (parent_sections) |ps| { - for (ps, §ions) |*parent, *section_elem| { - if (parent.*) |*p| { - section_elem.* = p.*; - p.owned = false; - } - } - } - errdefer for (sections) |opt_section| if (opt_section) |s| if (s.owned) gpa.free(s.data); - - var eh_frame_section: ?UnwindSection = null; - errdefer if (eh_frame_section) |s| if (s.owned) gpa.free(s.bytes); - - var debug_frame_section: ?UnwindSection = null; - errdefer if (debug_frame_section) |s| if (s.owned) gpa.free(s.bytes); - - var separate_debug_filename: ?[]const u8 = null; - var separate_debug_crc: ?u32 = null; - - for (shdrs) |*shdr| { - if (shdr.sh_type == elf.SHT_NULL or shdr.sh_type == elf.SHT_NOBITS) continue; - const name = mem.sliceTo(header_strings[shdr.sh_name..], 0); - - if (mem.eql(u8, name, ".gnu_debuglink")) { - if (mapped_mem.len < shdr.sh_offset + shdr.sh_size) return error.InvalidDebugInfo; - const gnu_debuglink = mapped_mem[@intCast(shdr.sh_offset)..][0..@intCast(shdr.sh_size)]; - const debug_filename = mem.sliceTo(@as([*:0]const u8, @ptrCast(gnu_debuglink.ptr)), 0); - 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, endian); - separate_debug_filename = debug_filename; - continue; - } - - const section_id: union(enum) { - dwarf: Dwarf.Section.Id, - eh_frame, - debug_frame, - } = s: { - inline for (@typeInfo(Dwarf.Section.Id).@"enum".fields) |s| { - if (mem.eql(u8, "." ++ s.name, name)) { - break :s .{ .dwarf = @enumFromInt(s.value) }; - } - } - if (mem.eql(u8, ".eh_frame", name)) break :s .eh_frame; - if (mem.eql(u8, ".debug_frame", name)) break :s .debug_frame; - continue; - }; - - switch (section_id) { - .dwarf => |i| if (sections[@intFromEnum(i)] != null) continue, - .eh_frame => if (eh_frame_section != null) continue, - .debug_frame => if (debug_frame_section != null) continue, - } - - if (mapped_mem.len < shdr.sh_offset + shdr.sh_size) return error.InvalidDebugInfo; - const raw_section_bytes = mapped_mem[@intCast(shdr.sh_offset)..][0..@intCast(shdr.sh_size)]; - - const section_bytes: []const u8, const section_owned: bool = section: { - if ((shdr.sh_flags & elf.SHF_COMPRESSED) == 0) { - break :section .{ raw_section_bytes, false }; - } - var section_reader: Reader = .fixed(raw_section_bytes); - const chdr = section_reader.takeStruct(elf.Chdr, endian) catch continue; - if (chdr.ch_type != .ZLIB) continue; - - var decompress: std.compress.flate.Decompress = .init(§ion_reader, .zlib, &.{}); - var decompressed_section: ArrayList(u8) = .empty; - defer decompressed_section.deinit(gpa); - decompress.reader.appendRemainingUnlimited(gpa, &decompressed_section) catch { - Dwarf.invalidDebugInfoDetected(); - continue; - }; - if (chdr.ch_size != decompressed_section.items.len) { - Dwarf.invalidDebugInfoDetected(); - continue; - } - break :section .{ try decompressed_section.toOwnedSlice(gpa), true }; - }; - switch (section_id) { - .dwarf => |id| sections[@intFromEnum(id)] = .{ - .data = section_bytes, - .owned = section_owned, - }, - .eh_frame => eh_frame_section = .{ - .vaddr = shdr.sh_addr, - .bytes = section_bytes, - .owned = section_owned, - }, - .debug_frame => debug_frame_section = .{ - .vaddr = shdr.sh_addr, - .bytes = section_bytes, - .owned = section_owned, - }, - } - } - - const missing_debug_info = - sections[@intFromEnum(Dwarf.Section.Id.debug_info)] == null or - sections[@intFromEnum(Dwarf.Section.Id.debug_abbrev)] == null or - sections[@intFromEnum(Dwarf.Section.Id.debug_str)] == null or - sections[@intFromEnum(Dwarf.Section.Id.debug_line)] == null; - - // Attempt to load debug info from an external file - // See: https://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html - if (missing_debug_info) { - // Only allow one level of debug info nesting - if (parent_mapped_mem) |_| { - 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 - debuginfod: { - const id = build_id orelse break :debuginfod; - switch (builtin.os.tag) { - .wasi, .windows => break :debuginfod, - else => {}, - } - const id_dir_path: []u8 = p: { - if (std.posix.getenv("DEBUGINFOD_CACHE_PATH")) |path| { - break :p try std.fmt.allocPrint(gpa, "{s}/{x}", .{ path, id }); - } - if (std.posix.getenv("XDG_CACHE_HOME")) |cache_path| { - if (cache_path.len > 0) { - break :p try std.fmt.allocPrint(gpa, "{s}/debuginfod_client/{x}", .{ cache_path, id }); - } - } - if (std.posix.getenv("HOME")) |home_path| { - break :p try std.fmt.allocPrint(gpa, "{s}/.cache/debuginfod_client/{x}", .{ home_path, id }); - } - break :debuginfod; - }; - defer gpa.free(id_dir_path); - if (!std.fs.path.isAbsolute(id_dir_path)) break :debuginfod; - - var id_dir = std.fs.openDirAbsolute(id_dir_path, .{}) catch break :debuginfod; - defer id_dir.close(); - - return load(gpa, .{ - .root_dir = .{ .path = id_dir_path, .handle = id_dir }, - .sub_path = "debuginfo", - }, null, separate_debug_crc, §ions, mapped_mem) catch break :debuginfod; - } - - const global_debug_directories = [_][]const u8{ - "/usr/lib/debug", - }; - - // <global debug directory>/.build-id/<2-character id prefix>/<id remainder>.debug - if (build_id) |id| blk: { - if (id.len < 3) break :blk; - - // Either md5 (16 bytes) or sha1 (20 bytes) are used here in practice - const extension = ".debug"; - var id_prefix_buf: [2]u8 = undefined; - var filename_buf: [38 + extension.len]u8 = undefined; - - _ = std.fmt.bufPrint(&id_prefix_buf, "{x}", .{id[0..1]}) catch unreachable; - const filename = std.fmt.bufPrint(&filename_buf, "{x}" ++ extension, .{id[1..]}) catch break :blk; - - for (global_debug_directories) |global_directory| { - const path: Path = .{ - .root_dir = .cwd(), - .sub_path = try std.fs.path.join(gpa, &.{ - global_directory, ".build-id", &id_prefix_buf, filename, - }), - }; - defer gpa.free(path.sub_path); - - return load(gpa, path, null, separate_debug_crc, §ions, mapped_mem) catch continue; - } - } - - // use the path from .gnu_debuglink, in the same search order as gdb - separate: { - const separate_filename = separate_debug_filename orelse break :separate; - if (mem.eql(u8, std.fs.path.basename(elf_file_path.sub_path), separate_filename)) - return error.MissingDebugInfo; - - exe_dir: { - const exe_dir_path = try std.fs.path.resolve(gpa, &.{ - elf_file_path.root_dir.path orelse ".", - std.fs.path.dirname(elf_file_path.sub_path) orelse ".", - }); - defer gpa.free(exe_dir_path); - var exe_dir = std.fs.openDirAbsolute(exe_dir_path, .{}) catch break :exe_dir; - defer exe_dir.close(); - - // <exe_dir>/<gnu_debuglink> - if (load( - gpa, - .{ - .root_dir = .{ .path = exe_dir_path, .handle = exe_dir }, - .sub_path = separate_filename, - }, - null, - separate_debug_crc, - §ions, - mapped_mem, - )) |em| { - return em; - } else |_| {} - - // <exe_dir>/.debug/<gnu_debuglink> - const path: Path = .{ - .root_dir = .{ .path = exe_dir_path, .handle = exe_dir }, - .sub_path = try std.fs.path.join(gpa, &.{ ".debug", separate_filename }), - }; - defer gpa.free(path.sub_path); - - if (load(gpa, path, null, separate_debug_crc, §ions, mapped_mem)) |em| { - return em; - } else |_| {} - } - - var cwd_buf: [std.fs.max_path_bytes]u8 = undefined; - const cwd_path = std.posix.realpath(".", &cwd_buf) catch break :separate; - - // <global debug directory>/<absolute folder of current binary>/<gnu_debuglink> - for (global_debug_directories) |global_directory| { - const path: Path = .{ - .root_dir = .cwd(), - .sub_path = try std.fs.path.join(gpa, &.{ global_directory, cwd_path, separate_filename }), - }; - defer gpa.free(path.sub_path); - if (load(gpa, path, null, separate_debug_crc, §ions, mapped_mem)) |em| { - return em; - } else |_| {} - } - } - - return error.MissingDebugInfo; - } - - var dwarf: Dwarf = .{ .sections = sections }; - try dwarf.open(gpa, endian); - return .{ - .dwarf = dwarf, - .eh_frame = eh_frame_section, - .debug_frame = debug_frame_section, - .mapped_file = parent_mapped_mem orelse mapped_mem, - .mapped_debug_file = if (parent_mapped_mem != null) mapped_mem else null, - }; -} - -const std = @import("../../std.zig"); -const Allocator = std.mem.Allocator; -const ArrayList = std.ArrayList; -const Dwarf = std.debug.Dwarf; -const Path = std.Build.Cache.Path; -const Reader = std.Io.Reader; -const mem = std.mem; -const elf = std.elf; - -const builtin = @import("builtin"); -const native_endian = builtin.cpu.arch.endian(); - -const ElfModule = @This(); |