Managing redundant typedefs from multiple vendors

Question

What are some of the best ways to manage redundant typedefs used for platform independence from multiple middleware (operating systems, protocol stacks) vendors in the C programming language.

e.g.:
target.h

/* inclusion lock etc */
typedef char CHAR;
typedef unsigned char BYTE;
typedef unsigned short int WORD;
/* ... more of the same ... */

OS_types.h

/* inclusion lock etc */
typedef char CHAR;
typedef unsigned char BYTE;
typedef unsigned short int WORD;
/* ... more of the same ... */

At some point the compiler recognizes that it has two redundant typedef symbols and bails out with an error because this is simply not allowed by definition in C.

Answer 1

One possible way to do this without modifying the vendor's header would be to use the preprocessor with some header wrappers, e.g.

mytypes.h

#define BYTE VENDOR1_BYTE
#include <vendor1/types.h>
#undef BYTE

#define BYTE VENDOR2_BYTE
#include <vendor2/types.h>
#undef BYTE

typedef unsigned char BYTE;

This would result in the vendor's code generating different typedefs but hopefully mapped to the same actual type (unsigned char in the example). If the vendors are using different underlying types for the same type names then the method will likely not work.