Cachalot

An error-handling library for C program.

Cachalot is more like a protocol rather than a library.

Here is the philosophy behind cachalot:

1. simple: only 8 APIs.
2. safe: if something wrong happens inside cachalot, the caller program will not be affected.

Here is the protocol behind cachalot:

1. If an error happens somewhere in the caller program, the caller program should call CACHALOT_CAUSE (and CACHALOT_MSG) to insert the error into cachalot and then return err to the upper calling function.
2. Depending on the context, the upper calling function should call CACHALOT_TRACE, CACHALOT_WRAP or CACHALOT_MSG and then return err to the upper calling function.
3. Finally, main function receive the error and call CACHALOT_STRINGLIZE to generate the error stack string, print or logging, and exit.