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| -rw-r--r-- | README.md | 15 |
1 files changed, 15 insertions, 0 deletions
@@ -13,3 +13,18 @@ For example: $ ./strerror 1 1: Operation not permitted [EPERM] ``` + +# hacking +The file `errlist` contains a list of symbolic constants (AKA C macros) that +can be expected to be found in `<errno.h>` on POSIX systems. Constants are +listed one per line. A one-line AWK command transforms this into the bulk +of `strerror.h`, along with some `printf` calls in `Makefile`. + +To add more errors (for instance, GNU or Linux specific stuff that doesn't +exist in POSIX), just add them, one per line, to `errlist` and re-run `make`. +Every constant (and I mean every, even standard C constants like `ERANGE` and +`EDOM`) is only included in the list if it is defined, so there are no +portability concerns with adding macros that don't exist. + +There is a problem with adding constants that expand to identical values, +though, so don't do that. |