LM_ReadMemoryEx in rust returns bool type instead of number of bytes about libmem

[rdbo]

It doesn't. It returns an Option<T>, where T is the type you're trying to read.
libmem C binding:

        pub(super) fn LM_ReadMemoryEx(
            pproc: *const lm_process_t,
            src: lm_address_t,
            dst: *mut lm_byte_t,
            size: lm_size_t,
        ) -> lm_size_t;

Rust API:

pub fn LM_ReadMemoryEx<T>(pproc: &lm_process_t, src: lm_address_t) -> Option<T> 

The size of the read would be the size of T.

If it fails, it returns None instead of Some(val)

[rdbo]

@shay11111111111111111111
If you're talking about the actual Windows function, yes, it does return a boolean. But, the last parameter of ReadProcessMemory is a pointer to a variable that will store the size of the read operation:

BOOL ReadProcessMemory(
  [in]  HANDLE  hProcess,
  [in]  LPCVOID lpBaseAddress,
  [out] LPVOID  lpBuffer,
  [in]  SIZE_T  nSize,
  [out] SIZE_T  *lpNumberOfBytesRead
);