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stage2: safety checks for slicing a null C pointer

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This commit is contained in:
Mitchell Hashimoto 2022-03-25 09:09:32 -07:00
parent d15bbebe2e
commit 01698528d1
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GPG Key ID: 523D5DC389D273BC
3 changed files with 25 additions and 0 deletions
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14
src/Sema.zig
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@ -19964,6 +19964,14 @@ fn analyzeSlice(
slice_ty = ptr_ptr_child_ty;
array_ty = ptr_ptr_child_ty;
elem_ty = ptr_ptr_child_ty.childType();
if (ptr_ptr_child_ty.ptrSize() == .C) {
if (try sema.resolveDefinedValue(block, ptr_src, ptr_or_slice)) |ptr_val| {
if (ptr_val.isNull()) {
return sema.fail(block, ptr_src, "slice of null pointer", .{});
}
}
}
},
.Slice => {
ptr_sentinel = ptr_ptr_child_ty.sentinel();
@ -20162,6 +20170,12 @@ fn analyzeSlice(
try sema.requireRuntimeBlock(block, src);
if (block.wantSafety()) {
// requirement: slicing C ptr is non-null
if (ptr_ptr_child_ty.isCPtr()) {
const is_non_null = try sema.analyzeIsNull(block, ptr_src, ptr, true);
try sema.addSafetyCheck(block, is_non_null, .unwrap_null);
}
// requirement: end <= len
const opt_len_inst = if (array_ty.zigTypeTag() == .Array)
try sema.addIntUnsigned(Type.usize, array_ty.arrayLenIncludingSentinel())

1
test/behavior/slice.zig
View File

@ -233,6 +233,7 @@ fn sliceFromLenToLen(a_slice: []u8, start: usize, end: usize) []u8 {
test "C pointer" {
if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest;
if (builtin.zig_backend == .stage2_c) return error.SkipZigTest;
var buf: [*c]const u8 = "kjdhfkjdhfdkjhfkfjhdfkjdhfkdjhfdkjhf";
var len: u32 = 10;

10
test/compile_errors/stage2/slice_of_null_pointer.zig Normal file
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@ -0,0 +1,10 @@
comptime {
var x: [*c]u8 = null;
var runtime_len: usize = 0;
var y = x[0..runtime_len];
_ = y;
}
// slice of null C pointer
//
// :4:14: error: slice of null pointer