Commit c1a30bd0d8
Changed files (7)
lib
std
debug
lib/std/debug/Dwarf/ElfModule.zig
@@ -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();
lib/std/debug/SelfInfo/ElfModule.zig
@@ -7,10 +7,12 @@ gnu_eh_frame: ?[]const u8,
pub const LookupCache = void;
pub const DebugInfo = struct {
- loaded_elf: ?Dwarf.ElfModule,
+ loaded_elf: ?ElfFile,
+ scanned_dwarf: bool,
unwind: [2]?Dwarf.Unwind,
pub const init: DebugInfo = .{
.loaded_elf = null,
+ .scanned_dwarf = false,
.unwind = @splat(null),
};
pub fn deinit(di: *DebugInfo, gpa: Allocator) void {
@@ -92,55 +94,92 @@ pub fn lookup(cache: *LookupCache, gpa: Allocator, address: usize) Error!ElfModu
};
return error.MissingDebugInfo;
}
-fn loadDwarf(module: *const ElfModule, gpa: Allocator, di: *DebugInfo) Error!void {
+fn loadElf(module: *const ElfModule, gpa: Allocator, di: *DebugInfo) Error!void {
+ std.debug.assert(di.loaded_elf == null);
+ std.debug.assert(!di.scanned_dwarf);
+
const load_result = if (module.name.len > 0) res: {
- break :res Dwarf.ElfModule.load(gpa, .{
- .root_dir = .cwd(),
- .sub_path = module.name,
- }, module.build_id, null, null, null);
+ var file = std.fs.cwd().openFile(module.name, .{}) catch return error.MissingDebugInfo;
+ defer file.close();
+ break :res ElfFile.load(gpa, file, module.build_id, &.native(module.name));
} else res: {
const path = std.fs.selfExePathAlloc(gpa) catch |err| switch (err) {
error.OutOfMemory => |e| return e,
else => return error.ReadFailed,
};
defer gpa.free(path);
- break :res Dwarf.ElfModule.load(gpa, .{
- .root_dir = .cwd(),
- .sub_path = path,
- }, module.build_id, null, null, null);
+ var file = std.fs.cwd().openFile(path, .{}) catch return error.MissingDebugInfo;
+ defer file.close();
+ break :res ElfFile.load(gpa, file, module.build_id, &.native(path));
};
di.loaded_elf = load_result catch |err| switch (err) {
- error.FileNotFound => return error.MissingDebugInfo,
-
error.OutOfMemory,
- error.InvalidDebugInfo,
- error.MissingDebugInfo,
error.Unexpected,
=> |e| return e,
- error.InvalidElfEndian,
+ error.Overflow,
+ error.TruncatedElfFile,
+ error.InvalidCompressedSection,
error.InvalidElfMagic,
error.InvalidElfVersion,
- error.InvalidUtf8,
- error.InvalidWtf8,
- error.EndOfStream,
- error.Overflow,
- error.UnimplementedDwarfForeignEndian, // this should be impossible as we're looking at the debug info for this process
+ error.InvalidElfClass,
+ error.InvalidElfEndian,
=> return error.InvalidDebugInfo,
- else => return error.ReadFailed,
+ error.SystemResources,
+ error.MemoryMappingNotSupported,
+ error.AccessDenied,
+ error.LockedMemoryLimitExceeded,
+ error.ProcessFdQuotaExceeded,
+ error.SystemFdQuotaExceeded,
+ => return error.ReadFailed,
};
+
+ const matches_native =
+ di.loaded_elf.?.endian == native_endian and
+ di.loaded_elf.?.is_64 == (@sizeOf(usize) == 8);
+
+ if (!matches_native) {
+ di.loaded_elf.?.deinit(gpa);
+ di.loaded_elf = null;
+ return error.InvalidDebugInfo;
+ }
}
pub fn getSymbolAtAddress(module: *const ElfModule, gpa: Allocator, di: *DebugInfo, address: usize) Error!std.debug.Symbol {
- if (di.loaded_elf == null) try module.loadDwarf(gpa, di);
+ if (di.loaded_elf == null) try module.loadElf(gpa, di);
const vaddr = address - module.load_offset;
- return di.loaded_elf.?.dwarf.getSymbol(gpa, native_endian, vaddr) catch |err| switch (err) {
- error.InvalidDebugInfo, error.MissingDebugInfo, error.OutOfMemory => |e| return e,
- error.ReadFailed,
- error.EndOfStream,
- error.Overflow,
- error.StreamTooLong,
- => return error.InvalidDebugInfo,
+ if (di.loaded_elf.?.dwarf) |*dwarf| {
+ if (!di.scanned_dwarf) {
+ dwarf.open(gpa, native_endian) catch |err| switch (err) {
+ error.InvalidDebugInfo,
+ error.MissingDebugInfo,
+ error.OutOfMemory,
+ => |e| return e,
+ error.EndOfStream,
+ error.Overflow,
+ error.ReadFailed,
+ error.StreamTooLong,
+ => return error.InvalidDebugInfo,
+ };
+ di.scanned_dwarf = true;
+ }
+ return dwarf.getSymbol(gpa, native_endian, vaddr) catch |err| switch (err) {
+ error.InvalidDebugInfo,
+ error.MissingDebugInfo,
+ error.OutOfMemory,
+ => |e| return e,
+ error.ReadFailed,
+ error.EndOfStream,
+ error.Overflow,
+ error.StreamTooLong,
+ => return error.InvalidDebugInfo,
+ };
+ }
+ // When there's no DWARF available, fall back to searching the symtab.
+ return di.loaded_elf.?.searchSymtab(gpa, vaddr) catch |err| switch (err) {
+ error.NoSymtab, error.NoStrtab => return error.MissingDebugInfo,
+ error.BadSymtab => return error.InvalidDebugInfo,
+ error.OutOfMemory => |e| return e,
};
}
fn prepareUnwindLookup(unwind: *Dwarf.Unwind, gpa: Allocator) Error!void {
@@ -166,7 +205,7 @@ fn loadUnwindInfo(module: *const ElfModule, gpa: Allocator, di: *DebugInfo) Erro
} else unwinds: {
// There is no `.eh_frame_hdr` section. There may still be an `.eh_frame` or `.debug_frame`
// section, but we'll have to load the binary to get at it.
- try module.loadDwarf(gpa, di);
+ try module.loadElf(gpa, di);
const opt_debug_frame = &di.loaded_elf.?.debug_frame;
const opt_eh_frame = &di.loaded_elf.?.eh_frame;
// If both are present, we can't just pick one -- the info could be split between them.
@@ -232,6 +271,7 @@ const ElfModule = @This();
const std = @import("../../std.zig");
const Allocator = std.mem.Allocator;
const Dwarf = std.debug.Dwarf;
+const ElfFile = std.debug.ElfFile;
const elf = std.elf;
const mem = std.mem;
const Error = std.debug.SelfInfo.Error;
lib/std/debug/Dwarf.zig
@@ -30,7 +30,6 @@ pub const expression = @import("Dwarf/expression.zig");
pub const abi = @import("Dwarf/abi.zig");
pub const call_frame = @import("Dwarf/call_frame.zig");
pub const Unwind = @import("Dwarf/Unwind.zig");
-pub const ElfModule = @import("Dwarf/ElfModule.zig");
/// Useful to temporarily enable while working on this file.
const debug_debug_mode = false;
lib/std/debug/ElfFile.zig
@@ -0,0 +1,536 @@
+//! A helper type for loading an ELF file and collecting its DWARF debug information, unwind
+//! information, and symbol table.
+
+is_64: bool,
+endian: Endian,
+
+/// This is `null` iff any of the required DWARF sections were missing. `ElfFile.load` does *not*
+/// call `Dwarf.open`, `Dwarf.scanAllFunctions`, etc; that is the caller's responsibility.
+dwarf: ?Dwarf,
+
+/// If non-`null`, describes the `.eh_frame` section, which can be used with `Dwarf.Unwind`.
+eh_frame: ?UnwindSection,
+/// If non-`null`, describes the `.debug_frame` section, which can be used with `Dwarf.Unwind`.
+debug_frame: ?UnwindSection,
+
+/// If non-`null`, this is the contents of the `.strtab` section.
+strtab: ?[]const u8,
+/// If non-`null`, describes the `.symtab` section.
+symtab: ?SymtabSection,
+
+/// Binary search table lazily populated by `searchSymtab`.
+symbol_search_table: ?[]u64,
+
+/// The memory-mapped ELF file, which is referenced by `dwarf`. This field is here only so that
+/// this memory can be unmapped by `ElfFile.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 `ElfFile.deinit`.
+mapped_debug_file: ?[]align(std.heap.page_size_min) const u8,
+
+arena: std.heap.ArenaAllocator.State,
+
+pub const UnwindSection = struct {
+ vaddr: u64,
+ bytes: []const u8,
+};
+pub const SymtabSection = struct {
+ entry_size: u64,
+ bytes: []const u8,
+};
+
+pub const DebugInfoSearchPaths = struct {
+ /// The location of a debuginfod client directory, which acts as a search path for build IDs. If
+ /// given, we can load from this directory opportunistically, but make no effort to populate it.
+ /// To avoid allocation when building the search paths, this is given as two components which
+ /// will be concatenated.
+ debuginfod_client: ?[2][]const u8,
+ /// All "global debug directories" on the system. These are used as search paths for both debug
+ /// links and build IDs. On typical systems this is just "/usr/lib/debug".
+ global_debug: []const []const u8,
+ /// The path to the dirname of the ELF file, which acts as a search path for debug links.
+ exe_dir: ?[]const u8,
+
+ pub const none: DebugInfoSearchPaths = .{
+ .debuginfod_client = null,
+ .global_debug = &.{},
+ .exe_dir = null,
+ };
+
+ pub fn native(exe_path: []const u8) DebugInfoSearchPaths {
+ return .{
+ .debuginfod_client = p: {
+ if (std.posix.getenv("DEBUGINFOD_CACHE_PATH")) |p| {
+ break :p .{ p, "" };
+ }
+ if (std.posix.getenv("XDG_CACHE_HOME")) |cache_path| {
+ break :p .{ cache_path, "/debuginfod_client" };
+ }
+ if (std.posix.getenv("HOME")) |home_path| {
+ break :p .{ home_path, "/.cache/debuginfod_client" };
+ }
+ break :p null;
+ },
+ .global_debug = &.{
+ "/usr/lib/debug",
+ },
+ .exe_dir = std.fs.path.dirname(exe_path) orelse ".",
+ };
+ }
+};
+
+pub fn deinit(ef: *ElfFile, gpa: Allocator) void {
+ if (ef.dwarf) |*dwarf| dwarf.deinit(gpa);
+ if (ef.symbol_search_table) |t| gpa.free(t);
+ var arena = ef.arena.promote(gpa);
+ arena.deinit();
+
+ std.posix.munmap(ef.mapped_file);
+ if (ef.mapped_debug_file) |m| std.posix.munmap(m);
+
+ ef.* = undefined;
+}
+
+pub const LoadError = error{
+ OutOfMemory,
+ Overflow,
+ TruncatedElfFile,
+ InvalidCompressedSection,
+ InvalidElfMagic,
+ InvalidElfVersion,
+ InvalidElfClass,
+ InvalidElfEndian,
+ // The remaining errors all occur when attemping to stat or mmap a file.
+ SystemResources,
+ MemoryMappingNotSupported,
+ AccessDenied,
+ LockedMemoryLimitExceeded,
+ ProcessFdQuotaExceeded,
+ SystemFdQuotaExceeded,
+ Unexpected,
+};
+
+pub fn load(
+ gpa: Allocator,
+ elf_file: std.fs.File,
+ opt_build_id: ?[]const u8,
+ di_search_paths: *const DebugInfoSearchPaths,
+) LoadError!ElfFile {
+ var arena_instance: std.heap.ArenaAllocator = .init(gpa);
+ errdefer arena_instance.deinit();
+ const arena = arena_instance.allocator();
+
+ var result = loadInner(arena, elf_file, null) catch |err| switch (err) {
+ error.CrcMismatch => unreachable, // we passed crc as null
+ else => |e| return e,
+ };
+ errdefer std.posix.munmap(result.mapped_mem);
+
+ // `loadInner` did most of the work, but we might need to load an external debug info file
+
+ const di_mapped_mem: ?[]align(std.heap.page_size_min) const u8 = load_di: {
+ if (result.sections.get(.debug_info) != null and
+ result.sections.get(.debug_abbrev) != null and
+ result.sections.get(.debug_str) != null and
+ result.sections.get(.debug_line) != null)
+ {
+ // The info is already loaded from this file alone!
+ break :load_di null;
+ }
+
+ // We're missing some debug info---let's try and load it from a separate file.
+
+ build_id: {
+ const build_id = opt_build_id orelse break :build_id;
+ if (build_id.len < 3) break :build_id;
+
+ for (di_search_paths.global_debug) |global_debug| {
+ if (try loadSeparateDebugFile(arena, &result, null, "{s}/.build-id/{x}/{x}.debug", .{
+ global_debug,
+ build_id[0..1],
+ build_id[1..],
+ })) |mapped| break :load_di mapped;
+ }
+
+ if (di_search_paths.debuginfod_client) |components| {
+ if (try loadSeparateDebugFile(arena, &result, null, "{s}{s}/{x}/debuginfo", .{
+ components[0],
+ components[1],
+ build_id,
+ })) |mapped| break :load_di mapped;
+ }
+ }
+
+ debug_link: {
+ const section = result.sections.get(.gnu_debuglink) orelse break :debug_link;
+ const debug_filename = std.mem.sliceTo(section.bytes, 0);
+ const crc_offset = std.mem.alignForward(usize, debug_filename.len + 1, 4);
+ if (section.bytes.len < crc_offset + 4) break :debug_link;
+ const debug_crc = std.mem.readInt(u32, section.bytes[crc_offset..][0..4], result.endian);
+
+ const exe_dir = di_search_paths.exe_dir orelse break :debug_link;
+
+ if (try loadSeparateDebugFile(arena, &result, debug_crc, "{s}/{s}", .{
+ exe_dir,
+ debug_filename,
+ })) |mapped| break :load_di mapped;
+ if (try loadSeparateDebugFile(arena, &result, debug_crc, "{s}/.debug/{s}", .{
+ exe_dir,
+ debug_filename,
+ })) |mapped| break :load_di mapped;
+ for (di_search_paths.global_debug) |global_debug| {
+ // This looks like a bug; it isn't. They really do embed the absolute path to the
+ // exe's dirname, *under* the global debug path.
+ if (try loadSeparateDebugFile(arena, &result, debug_crc, "{s}/{s}/{s}", .{
+ global_debug,
+ exe_dir,
+ debug_filename,
+ })) |mapped| break :load_di mapped;
+ }
+ }
+
+ break :load_di null;
+ };
+ errdefer comptime unreachable;
+
+ return .{
+ .is_64 = result.is_64,
+ .endian = result.endian,
+ .dwarf = dwarf: {
+ if (result.sections.get(.debug_info) == null or
+ result.sections.get(.debug_abbrev) == null or
+ result.sections.get(.debug_str) == null or
+ result.sections.get(.debug_line) == null)
+ {
+ break :dwarf null; // debug info not present
+ }
+ var sections: Dwarf.SectionArray = @splat(null);
+ inline for (@typeInfo(Dwarf.Section.Id).@"enum".fields) |f| {
+ if (result.sections.get(@field(Section.Id, f.name))) |s| {
+ sections[f.value] = .{ .data = s.bytes, .owned = false };
+ }
+ }
+ break :dwarf .{ .sections = sections };
+ },
+ .eh_frame = if (result.sections.get(.eh_frame)) |s| .{
+ .vaddr = s.header.sh_addr,
+ .bytes = s.bytes,
+ } else null,
+ .debug_frame = if (result.sections.get(.debug_frame)) |s| .{
+ .vaddr = s.header.sh_addr,
+ .bytes = s.bytes,
+ } else null,
+ .strtab = if (result.sections.get(.strtab)) |s| s.bytes else null,
+ .symtab = if (result.sections.get(.symtab)) |s| .{
+ .entry_size = s.header.sh_entsize,
+ .bytes = s.bytes,
+ } else null,
+ .symbol_search_table = null,
+ .mapped_file = result.mapped_mem,
+ .mapped_debug_file = di_mapped_mem,
+ .arena = arena_instance.state,
+ };
+}
+
+pub fn searchSymtab(ef: *ElfFile, gpa: Allocator, vaddr: u64) error{
+ NoSymtab,
+ NoStrtab,
+ BadSymtab,
+ OutOfMemory,
+}!std.debug.Symbol {
+ const symtab = ef.symtab orelse return error.NoSymtab;
+ const strtab = ef.strtab orelse return error.NoStrtab;
+
+ if (symtab.bytes.len % symtab.entry_size != 0) return error.BadSymtab;
+
+ const swap_endian = ef.endian != @import("builtin").cpu.arch.endian();
+
+ switch (ef.is_64) {
+ inline true, false => |is_64| {
+ const Sym = if (is_64) elf.Elf64_Sym else elf.Elf32_Sym;
+ if (symtab.entry_size != @sizeOf(Sym)) return error.BadSymtab;
+ const symbols: []align(1) const Sym = @ptrCast(symtab.bytes);
+ if (ef.symbol_search_table == null) {
+ ef.symbol_search_table = try buildSymbolSearchTable(gpa, ef.endian, Sym, symbols);
+ }
+ const search_table = ef.symbol_search_table.?;
+ const SearchContext = struct {
+ swap_endian: bool,
+ target: u64,
+ symbols: []align(1) const Sym,
+ fn predicate(ctx: @This(), sym_index: u64) bool {
+ // We need to return `true` for the first N items, then `false` for the rest --
+ // the index we'll get out is the first `false` one. So, we'll return `true` iff
+ // the target address is after the *end* of this symbol. This synchronizes with
+ // the logic in `buildSymbolSearchTable` which sorts by *end* address.
+ var sym = ctx.symbols[sym_index];
+ if (ctx.swap_endian) std.mem.byteSwapAllFields(Sym, &sym);
+ const sym_end = sym.st_value + sym.st_size;
+ return ctx.target >= sym_end;
+ }
+ };
+ const sym_index_index = std.sort.partitionPoint(u64, search_table, @as(SearchContext, .{
+ .swap_endian = swap_endian,
+ .target = vaddr,
+ .symbols = symbols,
+ }), SearchContext.predicate);
+ if (sym_index_index == search_table.len) return .unknown;
+ var sym = symbols[search_table[sym_index_index]];
+ if (swap_endian) std.mem.byteSwapAllFields(Sym, &sym);
+ if (vaddr < sym.st_value or vaddr >= sym.st_value + sym.st_size) return .unknown;
+ return .{
+ .name = std.mem.sliceTo(strtab[sym.st_name..], 0),
+ .compile_unit_name = null,
+ .source_location = null,
+ };
+ },
+ }
+}
+
+fn buildSymbolSearchTable(gpa: Allocator, endian: Endian, comptime Sym: type, symbols: []align(1) const Sym) error{
+ OutOfMemory,
+ BadSymtab,
+}![]u64 {
+ var result: std.ArrayList(u64) = .empty;
+ defer result.deinit(gpa);
+
+ const swap_endian = endian != @import("builtin").cpu.arch.endian();
+
+ for (symbols, 0..) |sym_orig, sym_index| {
+ var sym = sym_orig;
+ if (swap_endian) std.mem.byteSwapAllFields(Sym, &sym);
+ if (sym.st_name == 0) continue;
+ if (sym.st_shndx == elf.SHN_UNDEF) continue;
+ try result.append(gpa, sym_index);
+ }
+
+ const SortContext = struct {
+ swap_endian: bool,
+ symbols: []align(1) const Sym,
+ fn lessThan(ctx: @This(), lhs_sym_index: u64, rhs_sym_index: u64) bool {
+ // We sort by *end* address, not start address. This matches up with logic in `searchSymtab`.
+ var lhs_sym = ctx.symbols[lhs_sym_index];
+ var rhs_sym = ctx.symbols[rhs_sym_index];
+ if (ctx.swap_endian) {
+ std.mem.byteSwapAllFields(Sym, &lhs_sym);
+ std.mem.byteSwapAllFields(Sym, &rhs_sym);
+ }
+ const lhs_val = lhs_sym.st_value + lhs_sym.st_size;
+ const rhs_val = rhs_sym.st_value + rhs_sym.st_size;
+ return lhs_val < rhs_val;
+ }
+ };
+ std.mem.sort(u64, result.items, @as(SortContext, .{
+ .swap_endian = swap_endian,
+ .symbols = symbols,
+ }), SortContext.lessThan);
+
+ return result.toOwnedSlice(gpa);
+}
+
+/// Only used locally, during `load`.
+const Section = struct {
+ header: elf.Elf64_Shdr,
+ bytes: []const u8,
+ const Id = enum {
+ // DWARF sections: see `Dwarf.Section.Id`.
+ debug_info,
+ debug_abbrev,
+ debug_str,
+ debug_str_offsets,
+ debug_line,
+ debug_line_str,
+ debug_ranges,
+ debug_loclists,
+ debug_rnglists,
+ debug_addr,
+ debug_names,
+ // Then anything else we're interested in.
+ gnu_debuglink,
+ eh_frame,
+ debug_frame,
+ symtab,
+ strtab,
+ };
+ const Array = std.enums.EnumArray(Section.Id, ?Section);
+};
+
+fn loadSeparateDebugFile(arena: Allocator, main_loaded: *LoadInnerResult, opt_crc: ?u32, comptime fmt: []const u8, args: anytype) Allocator.Error!?[]align(std.heap.page_size_min) const u8 {
+ const path = try std.fmt.allocPrint(arena, fmt, args);
+ const elf_file = std.fs.cwd().openFile(path, .{}) catch return null;
+ defer elf_file.close();
+
+ const result = loadInner(arena, elf_file, opt_crc) catch |err| switch (err) {
+ error.OutOfMemory => |e| return e,
+ error.CrcMismatch => return null,
+ else => return null,
+ };
+ errdefer comptime unreachable;
+
+ const have_debug_sections = inline for (@as([]const []const u8, &.{
+ "debug_info",
+ "debug_abbrev",
+ "debug_str",
+ "debug_line",
+ })) |name| {
+ const s = @field(Section.Id, name);
+ if (main_loaded.sections.get(s) == null and result.sections.get(s) != null) {
+ break false;
+ }
+ } else true;
+
+ if (result.is_64 != main_loaded.is_64 or
+ result.endian != main_loaded.endian or
+ !have_debug_sections)
+ {
+ std.posix.munmap(result.mapped_mem);
+ return null;
+ }
+
+ inline for (@typeInfo(Dwarf.Section.Id).@"enum".fields) |f| {
+ const id = @field(Section.Id, f.name);
+ if (main_loaded.sections.get(id) == null) {
+ main_loaded.sections.set(id, result.sections.get(id));
+ }
+ }
+
+ return result.mapped_mem;
+}
+
+const LoadInnerResult = struct {
+ is_64: bool,
+ endian: Endian,
+ sections: Section.Array,
+ mapped_mem: []align(std.heap.page_size_min) const u8,
+};
+fn loadInner(
+ arena: Allocator,
+ elf_file: std.fs.File,
+ opt_crc: ?u32,
+) (LoadError || error{CrcMismatch})!LoadInnerResult {
+ const mapped_mem: []align(std.heap.page_size_min) const u8 = mapped: {
+ const file_len = std.math.cast(
+ usize,
+ elf_file.getEndPos() catch |err| switch (err) {
+ error.PermissionDenied => unreachable, // not asking for PROT_EXEC
+ else => |e| return e,
+ },
+ ) 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, // not using FIXED_NOREPLACE
+ error.PermissionDenied => unreachable, // not asking for PROT_EXEC
+ else => |e| return e,
+ };
+ };
+
+ if (opt_crc) |crc| {
+ if (std.hash.crc.Crc32.hash(mapped_mem) != crc) {
+ return error.CrcMismatch;
+ }
+ }
+ errdefer std.posix.munmap(mapped_mem);
+
+ var fr: std.Io.Reader = .fixed(mapped_mem);
+
+ const header = elf.Header.read(&fr) catch |err| switch (err) {
+ error.ReadFailed => unreachable,
+ error.EndOfStream => return error.TruncatedElfFile,
+
+ error.InvalidElfMagic,
+ error.InvalidElfVersion,
+ error.InvalidElfClass,
+ error.InvalidElfEndian,
+ => |e| return e,
+ };
+ const endian = header.endian;
+
+ const shstrtab_shdr_off = try std.math.add(
+ u64,
+ header.shoff,
+ try std.math.mul(u64, header.shstrndx, header.shentsize),
+ );
+ fr.seek = std.math.cast(usize, shstrtab_shdr_off) orelse return error.Overflow;
+ const shstrtab: []const u8 = if (header.is_64) shstrtab: {
+ const shdr = fr.takeStruct(elf.Elf64_Shdr, endian) catch return error.TruncatedElfFile;
+ if (shdr.sh_offset + shdr.sh_size > mapped_mem.len) return error.TruncatedElfFile;
+ break :shstrtab mapped_mem[@intCast(shdr.sh_offset)..][0..@intCast(shdr.sh_size)];
+ } else shstrtab: {
+ const shdr = fr.takeStruct(elf.Elf32_Shdr, endian) catch return error.TruncatedElfFile;
+ if (shdr.sh_offset + shdr.sh_size > mapped_mem.len) return error.TruncatedElfFile;
+ break :shstrtab mapped_mem[@intCast(shdr.sh_offset)..][0..@intCast(shdr.sh_size)];
+ };
+
+ var sections: Section.Array = .initFill(null);
+
+ var it = header.iterateSectionHeadersBuffer(mapped_mem);
+ while (it.next() catch return error.TruncatedElfFile) |shdr| {
+ if (shdr.sh_type == elf.SHT_NULL or shdr.sh_type == elf.SHT_NOBITS) continue;
+ if (shdr.sh_name > shstrtab.len) return error.TruncatedElfFile;
+ const name = std.mem.sliceTo(shstrtab[@intCast(shdr.sh_name)..], 0);
+
+ const section_id: Section.Id = inline for (@typeInfo(Section.Id).@"enum".fields) |s| {
+ if (std.mem.eql(u8, "." ++ s.name, name)) {
+ break @enumFromInt(s.value);
+ }
+ } else continue;
+
+ if (sections.get(section_id) != null) continue;
+
+ if (shdr.sh_offset + shdr.sh_size > mapped_mem.len) return error.TruncatedElfFile;
+ const raw_section_bytes = mapped_mem[@intCast(shdr.sh_offset)..][0..@intCast(shdr.sh_size)];
+ const section_bytes: []const u8 = bytes: {
+ if ((shdr.sh_flags & elf.SHF_COMPRESSED) == 0) break :bytes raw_section_bytes;
+
+ var section_reader: std.Io.Reader = .fixed(raw_section_bytes);
+ const ch_type: elf.COMPRESS, const ch_size: u64 = if (header.is_64) ch: {
+ const chdr = section_reader.takeStruct(elf.Elf64_Chdr, endian) catch return error.InvalidCompressedSection;
+ break :ch .{ chdr.ch_type, chdr.ch_size };
+ } else ch: {
+ const chdr = section_reader.takeStruct(elf.Elf32_Chdr, endian) catch return error.InvalidCompressedSection;
+ break :ch .{ chdr.ch_type, chdr.ch_size };
+ };
+ if (ch_type != .ZLIB) {
+ // The compression algorithm is unsupported, but don't make that a hard error; the
+ // file might still be valid, and we might still be okay without this section.
+ continue;
+ }
+
+ const buf = try arena.alloc(u8, ch_size);
+ var fw: std.Io.Writer = .fixed(buf);
+ var decompress: std.compress.flate.Decompress = .init(§ion_reader, .zlib, &.{});
+ const n = decompress.reader.streamRemaining(&fw) catch |err| switch (err) {
+ // If a write failed, then `buf` filled up, so `ch_size` was incorrect
+ error.WriteFailed => return error.InvalidCompressedSection,
+ // If a read failed, flate expected the section to have more data
+ error.ReadFailed => return error.InvalidCompressedSection,
+ };
+ // It's also an error if the data is shorter than expected.
+ if (n != buf.len) return error.InvalidCompressedSection;
+ break :bytes buf;
+ };
+ sections.set(section_id, .{ .header = shdr, .bytes = section_bytes });
+ }
+
+ return .{
+ .is_64 = header.is_64,
+ .endian = endian,
+ .sections = sections,
+ .mapped_mem = mapped_mem,
+ };
+}
+
+const std = @import("std");
+const Endian = std.builtin.Endian;
+const Dwarf = std.debug.Dwarf;
+const ElfFile = @This();
+const Allocator = std.mem.Allocator;
+const elf = std.elf;
lib/std/debug/Info.zig
@@ -9,7 +9,7 @@
const std = @import("../std.zig");
const Allocator = std.mem.Allocator;
const Path = std.Build.Cache.Path;
-const Dwarf = std.debug.Dwarf;
+const ElfFile = std.debug.ElfFile;
const assert = std.debug.assert;
const Coverage = std.debug.Coverage;
const SourceLocation = std.debug.Coverage.SourceLocation;
@@ -17,28 +17,35 @@ const SourceLocation = std.debug.Coverage.SourceLocation;
const Info = @This();
/// Sorted by key, ascending.
-address_map: std.AutoArrayHashMapUnmanaged(u64, Dwarf.ElfModule),
+address_map: std.AutoArrayHashMapUnmanaged(u64, ElfFile),
/// Externally managed, outlives this `Info` instance.
coverage: *Coverage,
-pub const LoadError = Dwarf.ElfModule.LoadError;
+pub const LoadError = std.fs.File.OpenError || ElfFile.LoadError || std.debug.Dwarf.ScanError || error{MissingDebugInfo};
pub fn load(gpa: Allocator, path: Path, coverage: *Coverage) LoadError!Info {
- var elf_module = try Dwarf.ElfModule.load(gpa, path, null, null, null, null);
- // This is correct because `Dwarf.ElfModule` currently only supports native-endian ELF files.
- const endian = @import("builtin").target.cpu.arch.endian();
- try elf_module.dwarf.populateRanges(gpa, endian);
+ var file = try path.root_dir.handle.openFile(path.sub_path, .{});
+ defer file.close();
+
+ var elf_file: ElfFile = try .load(gpa, file, null, &.none);
+ errdefer elf_file.deinit(gpa);
+
+ if (elf_file.dwarf == null) return error.MissingDebugInfo;
+ try elf_file.dwarf.?.open(gpa, elf_file.endian);
+ try elf_file.dwarf.?.populateRanges(gpa, elf_file.endian);
+
var info: Info = .{
.address_map = .{},
.coverage = coverage,
};
- try info.address_map.put(gpa, 0, elf_module);
+ try info.address_map.put(gpa, 0, elf_file);
+ errdefer comptime unreachable; // elf_file is owned by the map now
return info;
}
pub fn deinit(info: *Info, gpa: Allocator) void {
- for (info.address_map.values()) |*elf_module| {
- elf_module.dwarf.deinit(gpa);
+ for (info.address_map.values()) |*elf_file| {
+ elf_file.dwarf.?.deinit(gpa);
}
info.address_map.deinit(gpa);
info.* = undefined;
@@ -58,8 +65,6 @@ pub fn resolveAddresses(
) ResolveAddressesError!void {
assert(sorted_pc_addrs.len == output.len);
if (info.address_map.entries.len != 1) @panic("TODO");
- const elf_module = &info.address_map.values()[0];
- // This is correct because `Dwarf.ElfModule` currently only supports native-endian ELF files.
- const endian = @import("builtin").target.cpu.arch.endian();
- return info.coverage.resolveAddressesDwarf(gpa, endian, sorted_pc_addrs, output, &elf_module.dwarf);
+ const elf_file = &info.address_map.values()[0];
+ return info.coverage.resolveAddressesDwarf(gpa, elf_file.endian, sorted_pc_addrs, output, &elf_file.dwarf.?);
}
lib/std/debug/SelfInfo.zig
@@ -78,6 +78,7 @@ pub fn getSymbolAtAddress(self: *SelfInfo, gpa: Allocator, address: usize) Error
pub fn getModuleNameForAddress(self: *SelfInfo, gpa: Allocator, address: usize) Error![]const u8 {
comptime assert(target_supported);
const module: Module = try .lookup(&self.lookup_cache, gpa, address);
+ if (module.name.len == 0) return error.MissingDebugInfo;
return module.name;
}
lib/std/debug.zig
@@ -18,6 +18,7 @@ const root = @import("root");
pub const Dwarf = @import("debug/Dwarf.zig");
pub const Pdb = @import("debug/Pdb.zig");
+pub const ElfFile = @import("debug/ElfFile.zig");
pub const SelfInfo = @import("debug/SelfInfo.zig");
pub const Info = @import("debug/Info.zig");
pub const Coverage = @import("debug/Coverage.zig");