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link/wasm: fix writing past the end of debug info buffer

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The function `writeDbgInfoNopsBuffered` was based on the function
`pwriteDbgInfoNops`, originally written by me, and then modified to
write to a memory buffer instead of an open file. When writing to a
file, any extra bytes beyond the end of the file extend the size of
the file, and the function body of `pwriteDbgInfoNops` takes advantage
of this when `next_padding_bytes` causes the write to go beyond the
end of the file. However, when writing to a memory buffer, the
underlying array list must be expanded if the write would cause the
buffer to expand.
This commit is contained in:
Andrew Kelley 2022-06-10 17:55:17 -07:00
parent 3c3bc5af29
commit 6bf529dc38
1 changed files with 28 additions and 26 deletions
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54
src/link/Dwarf.zig
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@ -352,6 +352,7 @@ pub const DeclState = struct {
const fields = ty.structFields();
for (fields.keys()) |field_name, field_index| {
const field = fields.get(field_name).?;
if (!field.ty.hasRuntimeBits()) continue;
// DW.AT.member
try dbg_info_buffer.ensureUnusedCapacity(field_name.len + 2);
dbg_info_buffer.appendAssumeCapacity(@enumToInt(AbbrevKind.struct_member));
@ -1037,6 +1038,7 @@ pub fn commitDeclState(
}
}
log.debug("updateDeclDebugInfoAllocation for '{s}'", .{decl.name});
try self.updateDeclDebugInfoAllocation(file, atom, @intCast(u32, dbg_info_buffer.items.len));
while (decl_state.abbrev_relocs.popOrNull()) |reloc| {
@ -1098,6 +1100,7 @@ pub fn commitDeclState(
}
}
log.debug("writeDeclDebugInfo for '{s}", .{decl.name});
try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
}
@ -1141,7 +1144,10 @@ fn updateDeclDebugInfoAllocation(self: *Dwarf, file: *File, atom: *Atom, len: u3
},
.wasm => {
const wasm_file = file.cast(File.Wasm).?;
writeDbgInfoNopsBuffered(wasm_file.debug_info.items, atom.off, 0, &.{0}, atom.len, false);
const segment_index = try wasm_file.getDebugInfoIndex();
const segment = &wasm_file.segments.items[segment_index];
const offset = segment.offset + atom.off;
try writeDbgInfoNopsToArrayList(gpa, &wasm_file.debug_info, offset, 0, &.{0}, atom.len, false);
},
else => unreachable,
}
@ -1283,8 +1289,12 @@ fn writeDeclDebugInfo(self: *Dwarf, file: *File, atom: *Atom, dbg_info_buf: []co
debug_info.items.len = needed_size;
}
const offset = segment.offset + atom.off;
writeDbgInfoNopsBuffered(
debug_info.items,
log.debug(" writeDbgInfoNopsToArrayList debug_info_len={d} offset={d} content_len={d} next_padding_size={d}", .{
debug_info.items.len, offset, dbg_info_buf.len, next_padding_size,
});
try writeDbgInfoNopsToArrayList(
gpa,
debug_info,
offset,
prev_padding_size,
dbg_info_buf,
@ -1678,7 +1688,7 @@ pub fn writeDbgInfoHeader(self: *Dwarf, file: *File, module: *Module, low_pc: u6
},
.wasm => {
const wasm_file = file.cast(File.Wasm).?;
writeDbgInfoNopsBuffered(wasm_file.debug_info.items, 0, 0, di_buf.items, jmp_amt, false);
try writeDbgInfoNopsToArrayList(self.allocator, &wasm_file.debug_info, 0, 0, di_buf.items, jmp_amt, false);
},
else => unreachable,
}
@ -1884,35 +1894,25 @@ fn pwriteDbgInfoNops(
try file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
}
fn writeDbgInfoNopsBuffered(
buf: []u8,
fn writeDbgInfoNopsToArrayList(
gpa: Allocator,
buffer: *std.ArrayListUnmanaged(u8),
offset: u32,
prev_padding_size: usize,
content: []const u8,
next_padding_size: usize,
trailing_zero: bool,
) void {
assert(buf.len >= content.len + prev_padding_size + next_padding_size + @boolToInt(trailing_zero));
const tracy = trace(@src());
defer tracy.end();
{
var padding_left = prev_padding_size;
while (padding_left > 0) : (padding_left -= 1) {
buf[offset - padding_left] = @enumToInt(AbbrevKind.pad1);
}
}
mem.copy(u8, buf[offset..], content);
{
var padding_left = next_padding_size;
while (padding_left > 0) : (padding_left -= 1) {
buf[offset + content.len + padding_left] = @enumToInt(AbbrevKind.pad1);
}
}
) Allocator.Error!void {
try buffer.resize(gpa, @maximum(
buffer.items.len,
offset + content.len + next_padding_size + 1,
));
mem.set(u8, buffer.items[offset - prev_padding_size .. offset], @enumToInt(AbbrevKind.pad1));
mem.copy(u8, buffer.items[offset..], content);
mem.set(u8, buffer.items[offset + content.len ..][0..next_padding_size], @enumToInt(AbbrevKind.pad1));
if (trailing_zero) {
buf[offset + content.len + next_padding_size] = 0;
buffer.items[offset + content.len + next_padding_size] = 0;
}
}
@ -2249,7 +2249,9 @@ pub fn flushModule(self: *Dwarf, file: *File, module: *Module) !void {
try addDbgInfoErrorSet(arena, module, error_ty, self.target, &dbg_info_buffer);
try self.managed_atoms.append(gpa, atom);
log.debug("updateDeclDebugInfoAllocation in flushModule", .{});
try self.updateDeclDebugInfoAllocation(file, atom, @intCast(u32, dbg_info_buffer.items.len));
log.debug("writeDeclDebugInfo in flushModule", .{});
try self.writeDeclDebugInfo(file, atom, dbg_info_buffer.items);
const file_pos = blk: {