Import all system definitions of errno including their string representations, then layer our error definitions on top of that

README.md

@@ -62,13 +62,14 @@ Any function which uses the `PREPARE_ERROR` macro should have a return type of `
 
 The library uses integer values to specify error codes inside of its context. These integer return codes are defined in `akerror.h` in the form of `AKERR_xxxxx` where `xxxxx` is the name of the error code in question. See `akerror.h` for a list of defined errors and their descriptions. 
 
-You can define additional error types by defining additional `AKERR_xxxxx` values. Error values up to 127 are reserved by the library, so begin your error values at 128. Define a human-friendly name for the error with the `error_name_for_status` method:
+You can define additional error types by defining additional `AKERR_xxxxx` values. Error values up to 255 are reserved by the library (`AKERR_xxxxx` begins where `errno` stops), so please begin your error values at 256. When you add additional error codes, you need to define `-DAKERR_MAX_ERR_VALUE=n` to the compiler, where `n` is the maximum error code you have defined. If you define custom error codes, `AKERR_MAX_ERR_VALUE` must be >= 256 or the compiler will throw an error.
+
+Define a human-friendly name for the error with the `error_name_for_status` method somewhere in your code's initialization before the error may be used:
 
 ```c
 error_name_for_status(129, "Some Error Code Description")
 ```
 
-When you add additional error codes, you need to define `-DAKERR_MAX_ERR_VALUE=n` to the compiler, where `n` is the maximum error code you have defined.
 
 # Installation
 
@@ -78,6 +79,14 @@ cmake --build build
 cmake --install build
 ```
 
+## Templating and autogenerated code
+
+The build process relies upon `scripts/generrno.sh` which performs the following:
+
+1. Executes `errno --list` and gathers up the output
+1. Templates `include/akerror.tmpl.h` into `include/akerror.h` to set the `AKERR_LAST_ERRNO_VALUE` equal to the highest integer defined by `errno`
+2. Generates `src/errno.c` which contains a function called by `akerr_init` which initializes all of the status names for the previously defined values of `errno`.
+
 ## Dependencies
 
 This library depends upon `stdlib`. If you don't want to link against stdlib, you must modify the library code to include headers and link against a library that provides the following:
@@ -172,7 +181,7 @@ ATTEMPT {
 
 `PROCESS(errctx) { ... }` is the block within which you will handle any errors that were caught inside of the `ATTEMPT` block. See "Handling Errors" below.
 
-`FINISH(errctx, true)` terminates the attempt operation. The `FINISH` macro takes two arguments: the name of the akerr_ErrorContext, and a boolean regarding whether or not to pass unhandled errors up to the calling function. Unless you are inside of your `main()` method, this should be true. Inside of your `main()` method, call `FINISH_NORETURN(errctx)` instead.
+`FINISH(errctx, true)` terminates the attempt operation. The `FINISH` macro takes two arguments: the name of the akerr_ErrorContext, and a boolean regarding whether or not to pass unhandled errors up to the calling function. Unless you are inside of your `main()` method, this should be true. Inside of your `main()` method, call `FINISH_NORExbTURN(errctx)` instead.
 
 
 # Capturing errors