Commit 9901b9389e

mlugg <mlugg@mlugg.co.uk>
2025-09-11 14:42:51
std: fix 32-bit build and some unsafe casts
1 parent 7601b39
Changed files (4)
lib
lib/std/debug/Dwarf/Unwind.zig
@@ -433,7 +433,7 @@ pub const FrameDescriptionEntry = struct {
             .lsb_z => {
                 // There is augmentation data, but it's irrelevant to us -- it
                 // only contains the LSDA pointer, which we don't care about.
-                const aug_data_len = try r.takeLeb128(u64);
+                const aug_data_len = try r.takeLeb128(usize);
                 _ = try r.discardAll(aug_data_len);
             },
         }
@@ -463,17 +463,20 @@ pub fn prepareLookup(unwind: *Unwind, gpa: Allocator, addr_size_bytes: u8, endia
         switch (try EntryHeader.read(&r, entry_offset, section.id, endian)) {
             .cie => |cie_info| {
                 // Ignore CIEs for now; we'll parse them when we read a corresponding FDE
-                try r.discardAll(cie_info.bytes_len);
+                try r.discardAll(cast(usize, cie_info.bytes_len) orelse return error.EndOfStream);
                 continue;
             },
             .fde => |fde_info| {
-                var cie_r: Reader = .fixed(section.bytes[fde_info.cie_offset..]);
+                if (fde_info.cie_offset > section.bytes.len) return error.EndOfStream;
+                var cie_r: Reader = .fixed(section.bytes[@intCast(fde_info.cie_offset)..]);
                 const cie_info = switch (try EntryHeader.read(&cie_r, fde_info.cie_offset, section.id, endian)) {
                     .cie => |cie_info| cie_info,
                     .fde, .terminator => return bad(), // this is meant to be a CIE
                 };
-                const cie: CommonInformationEntry = try .parse(try cie_r.take(cie_info.bytes_len), section.id, addr_size_bytes);
-                const fde: FrameDescriptionEntry = try .parse(section.vaddr + r.seek, try r.take(fde_info.bytes_len), cie, endian);
+                const cie_bytes_len = cast(usize, cie_info.bytes_len) orelse return error.EndOfStream;
+                const fde_bytes_len = cast(usize, fde_info.bytes_len) orelse return error.EndOfStream;
+                const cie: CommonInformationEntry = try .parse(try cie_r.take(cie_bytes_len), section.id, addr_size_bytes);
+                const fde: FrameDescriptionEntry = try .parse(section.vaddr + r.seek, try r.take(fde_bytes_len), cie, endian);
                 try fde_list.append(gpa, .{
                     .pc_begin = fde.pc_begin,
                     .fde_offset = entry_offset,
@@ -537,27 +540,29 @@ pub fn lookupPc(unwind: *const Unwind, pc: u64, addr_size_bytes: u8, endian: End
 pub fn getFde(unwind: *const Unwind, fde_offset: u64, addr_size_bytes: u8, endian: Endian) !struct { Format, CommonInformationEntry, FrameDescriptionEntry } {
     const section = unwind.frame_section;
 
-    var fde_reader: Reader = .fixed(section.bytes[fde_offset..]);
+    if (fde_offset > section.bytes.len) return error.EndOfStream;
+    var fde_reader: Reader = .fixed(section.bytes[@intCast(fde_offset)..]);
     const fde_info = switch (try EntryHeader.read(&fde_reader, fde_offset, section.id, endian)) {
         .fde => |info| info,
         .cie, .terminator => return bad(), // This is meant to be an FDE
     };
 
     const cie_offset = fde_info.cie_offset;
-    var cie_reader: Reader = .fixed(section.bytes[cie_offset..]);
+    if (cie_offset > section.bytes.len) return error.EndOfStream;
+    var cie_reader: Reader = .fixed(section.bytes[@intCast(cie_offset)..]);
     const cie_info = switch (try EntryHeader.read(&cie_reader, cie_offset, section.id, endian)) {
         .cie => |info| info,
         .fde, .terminator => return bad(), // This is meant to be a CIE
     };
 
     const cie: CommonInformationEntry = try .parse(
-        try cie_reader.take(cie_info.bytes_len),
+        try cie_reader.take(cast(usize, cie_info.bytes_len) orelse return error.EndOfStream),
         section.id,
         addr_size_bytes,
     );
     const fde: FrameDescriptionEntry = try .parse(
         section.vaddr + fde_offset + fde_reader.seek,
-        try fde_reader.take(fde_info.bytes_len),
+        try fde_reader.take(cast(usize, fde_info.bytes_len) orelse return error.EndOfStream),
         cie,
         endian,
     );
@@ -566,9 +571,8 @@ pub fn getFde(unwind: *const Unwind, fde_offset: u64, addr_size_bytes: u8, endia
 }
 
 const EhPointerContext = struct {
-    // The address of the pointer field itself
+    /// The address of the pointer field itself
     pc_rel_base: u64,
-
     // These relative addressing modes are only used in specific cases, and
     // might not be available / required in all parsing contexts
     data_rel_base: ?u64 = null,
@@ -604,7 +608,7 @@ fn readEhPointerAbs(r: *Reader, enc_ty: EH.PE.Type, addr_size_bytes: u8, endian:
 fn readEhPointer(r: *Reader, enc: EH.PE, addr_size_bytes: u8, ctx: EhPointerContext, endian: Endian) !u64 {
     const offset = try readEhPointerAbs(r, enc.type, addr_size_bytes, endian);
     if (enc.indirect) return bad(); // GCC extension; not supported
-    const base = switch (enc.rel) {
+    const base: u64 = switch (enc.rel) {
         .abs, .aligned => 0,
         .pcrel => ctx.pc_rel_base,
         .textrel => ctx.text_rel_base orelse return bad(),
@@ -613,7 +617,10 @@ fn readEhPointer(r: *Reader, enc: EH.PE, addr_size_bytes: u8, ctx: EhPointerCont
         _ => return bad(),
     };
     return switch (offset) {
-        .signed => |s| @intCast(try std.math.add(i64, s, @as(i64, @intCast(base)))),
+        .signed => |s| if (s >= 0)
+            try std.math.add(u64, base, @intCast(s))
+        else
+            try std.math.sub(u64, base, @intCast(-s)),
         // absptr can actually contain signed values in some cases (aarch64 MachO)
         .unsigned => |u| u +% base,
     };
lib/std/debug/SelfInfo/ElfModule.zig
@@ -200,7 +200,7 @@ fn loadUnwindInfo(module: *const ElfModule, gpa: Allocator, di: *DebugInfo) Erro
             error.EndOfStream, error.Overflow => return error.InvalidDebugInfo,
             error.UnsupportedAddrSize => return error.UnsupportedDebugInfo,
         };
-        buf[0] = .initEhFrameHdr(header, section_vaddr, @ptrFromInt(module.load_offset + header.eh_frame_vaddr));
+        buf[0] = .initEhFrameHdr(header, section_vaddr, @ptrFromInt(@as(usize, @intCast(module.load_offset + header.eh_frame_vaddr))));
         break :unwinds buf[0..1];
     } else unwinds: {
         // There is no `.eh_frame_hdr` section. There may still be an `.eh_frame` or `.debug_frame`
@@ -208,20 +208,19 @@ fn loadUnwindInfo(module: *const ElfModule, gpa: Allocator, di: *DebugInfo) Erro
         try module.loadElf(gpa, di);
         const opt_debug_frame = &di.loaded_elf.?.debug_frame;
         const opt_eh_frame = &di.loaded_elf.?.eh_frame;
+        var i: usize = 0;
         // If both are present, we can't just pick one -- the info could be split between them.
         // `.debug_frame` is likely to be the more complete section, so we'll prioritize that one.
         if (opt_debug_frame.*) |*debug_frame| {
-            buf[0] = .initSection(.debug_frame, debug_frame.vaddr, debug_frame.bytes);
-            if (opt_eh_frame.*) |*eh_frame| {
-                buf[1] = .initSection(.eh_frame, eh_frame.vaddr, eh_frame.bytes);
-                break :unwinds buf[0..2];
-            }
-            break :unwinds buf[0..1];
-        } else if (opt_eh_frame.*) |*eh_frame| {
-            buf[0] = .initSection(.eh_frame, eh_frame.vaddr, eh_frame.bytes);
-            break :unwinds buf[0..1];
+            buf[i] = .initSection(.debug_frame, debug_frame.vaddr, debug_frame.bytes);
+            i += 1;
+        }
+        if (opt_eh_frame.*) |*eh_frame| {
+            buf[i] = .initSection(.eh_frame, eh_frame.vaddr, eh_frame.bytes);
+            i += 1;
         }
-        return error.MissingDebugInfo;
+        if (i == 0) return error.MissingDebugInfo;
+        break :unwinds buf[0..i];
     };
     errdefer for (unwinds) |*u| u.deinit(gpa);
     for (unwinds) |*u| try prepareUnwindLookup(u, gpa);
lib/std/debug/ElfFile.zig
@@ -19,7 +19,7 @@ strtab: ?[]const u8,
 symtab: ?SymtabSection,
 
 /// Binary search table lazily populated by `searchSymtab`.
-symbol_search_table: ?[]u64,
+symbol_search_table: ?[]usize,
 
 /// 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`.
@@ -259,7 +259,7 @@ pub fn searchSymtab(ef: *ElfFile, gpa: Allocator, vaddr: u64) error{
                 swap_endian: bool,
                 target: u64,
                 symbols: []align(1) const Sym,
-                fn predicate(ctx: @This(), sym_index: u64) bool {
+                fn predicate(ctx: @This(), sym_index: usize) 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
@@ -270,7 +270,7 @@ pub fn searchSymtab(ef: *ElfFile, gpa: Allocator, vaddr: u64) error{
                     return ctx.target >= sym_end;
                 }
             };
-            const sym_index_index = std.sort.partitionPoint(u64, search_table, @as(SearchContext, .{
+            const sym_index_index = std.sort.partitionPoint(usize, search_table, @as(SearchContext, .{
                 .swap_endian = swap_endian,
                 .target = vaddr,
                 .symbols = symbols,
@@ -291,8 +291,8 @@ pub fn searchSymtab(ef: *ElfFile, gpa: Allocator, vaddr: u64) error{
 fn buildSymbolSearchTable(gpa: Allocator, endian: Endian, comptime Sym: type, symbols: []align(1) const Sym) error{
     OutOfMemory,
     BadSymtab,
-}![]u64 {
-    var result: std.ArrayList(u64) = .empty;
+}![]usize {
+    var result: std.ArrayList(usize) = .empty;
     defer result.deinit(gpa);
 
     const swap_endian = endian != @import("builtin").cpu.arch.endian();
@@ -308,7 +308,7 @@ fn buildSymbolSearchTable(gpa: Allocator, endian: Endian, comptime Sym: type, sy
     const SortContext = struct {
         swap_endian: bool,
         symbols: []align(1) const Sym,
-        fn lessThan(ctx: @This(), lhs_sym_index: u64, rhs_sym_index: u64) bool {
+        fn lessThan(ctx: @This(), lhs_sym_index: usize, rhs_sym_index: usize) 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];
@@ -321,7 +321,7 @@ fn buildSymbolSearchTable(gpa: Allocator, endian: Endian, comptime Sym: type, sy
             return lhs_val < rhs_val;
         }
     };
-    std.mem.sort(u64, result.items, @as(SortContext, .{
+    std.mem.sort(usize, result.items, @as(SortContext, .{
         .swap_endian = swap_endian,
         .symbols = symbols,
     }), SortContext.lessThan);
@@ -504,7 +504,7 @@ fn loadInner(
                 continue;
             }
 
-            const buf = try arena.alloc(u8, ch_size);
+            const buf = try arena.alloc(u8, std.math.cast(usize, ch_size) orelse return error.Overflow);
             var fw: std.Io.Writer = .fixed(buf);
             var decompress: std.compress.flate.Decompress = .init(&section_reader, .zlib, &.{});
             const n = decompress.reader.streamRemaining(&fw) catch |err| switch (err) {
lib/std/elf.zig
@@ -744,7 +744,8 @@ pub const SectionHeaderBufferIterator = struct {
 
         const size: u64 = if (it.elf_header.is_64) @sizeOf(Elf64_Shdr) else @sizeOf(Elf32_Shdr);
         const offset = it.elf_header.shoff + size * it.index;
-        var reader = std.Io.Reader.fixed(it.buf[offset..]);
+        if (offset > it.buf.len) return error.EndOfStream;
+        var reader = std.Io.Reader.fixed(it.buf[@intCast(offset)..]);
 
         return takeShdr(&reader, it.elf_header);
     }