cpp!{{
#include <stdlib.h>
#include <errno.h>
}}
fn as_cstr_ptr(str: &str) -> Result<*const u8> {
let c_string: *const u8 = CString::new(str)?.as_bytes_with_nul().as_ptr();
Ok(c_string)
}
pub fn set_env_variable(name: &str, value: &str, overwrite: i32) -> Result<i32> {
let c_name_ptr = as_cstr_ptr(name)?;
let c_value_ptr = as_cstr_ptr(value)?;
let ret_val: i32 = cpp!(
unsafe [
c_name_ptr as "const char *",
c_value_ptr as "const char *",
overwrite as "int"
] -> i32 as "int"
{
return setenv(c_name_ptr, c_value_ptr, overwrite) != 0 ? errno : 0;
}
);
match ret_val {
0 => Ok(0),
code => Err(StdlibError::from(code)),
}
}
I have the above code snippet, where I am simply trying to call C++'s setenv method. For each of the argument passed to the macro, I see the assertion failure messages (from cpp_macros-0.5.5/src/lib.rs) of the following format.
"size_of for argument `{}` does not match between c++ and rust"
"align_of for argument `{}` does not match between c++ and rust"
Can some light be please shown on:
- when/why these assertions fail?
- how to fix them?
- what is the impact of the size and alignment mismatch?
I have the above code snippet, where I am simply trying to call C++'s setenv method. For each of the argument passed to the macro, I see the assertion failure messages (from cpp_macros-0.5.5/src/lib.rs) of the following format.
Can some light be please shown on: