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ipc_templating: Avoid depending on order of evaluation (#83)

f(x, x++) is unspecified behaviour in C++. An implementation could
evaluate arguments from left to right or from right to left.

`T(r.Buffers[a_index], r.BufferSizes[a_index++])` might
access the wrong buffer if `a_index++` is evaluated before the first
argument.

Fixes -Wsequence-point warnings
This commit is contained in:
Léo Lam 2018-05-05 20:41:08 +02:00 committed by SciresM
parent 30b9873ab3
commit cf50bad36c

View file

@ -184,11 +184,17 @@ T GetValueFromIpcParsedCommand(IpcParsedCommand& r, IpcCommand& out_c, u8 *point
const size_t old_c_size_offset = cur_c_size_offset;
const size_t old_pointer_buffer_offset = pointer_buffer_offset;
if constexpr (is_specialization_of<T, InBuffer>::value) {
return T(r.Buffers[a_index], r.BufferSizes[a_index++]);
const T& value{r.Buffers[a_index], r.BufferSizes[a_index]};
++a_index;
return value;
} else if constexpr (is_specialization_of<T, OutBuffer>::value) {
return T(r.Buffers[b_index], r.BufferSizes[b_index++]);
const T& value{r.Buffers[b_index], r.BufferSizes[b_index]};
++b_index;
return value;
} else if constexpr (is_specialization_of<T, InPointer>::value) {
return T(r.Statics[x_index], r.StaticSizes[x_index++]);
const T& value{r.Statics[x_index], r.StaticSizes[x_index]};
++x_index;
return value;
} else if constexpr (std::is_base_of<OutPointerWithServerSizeBase, T>::value) {
T t = T(pointer_buffer + old_pointer_buffer_offset);
ipcAddSendStatic(&out_c, pointer_buffer + old_pointer_buffer_offset, t.num_elements * sizeof(*t.pointer), c_index++);