The errorInternalThrowSys*() functions were marked as returning during coverage testing even when they had no possibility to return, i.e. the error parameter was set to constant true. This meant the compiler would treat the functions as returning even when they would not.
Instead create completely separate functions for coverage to use for THROW_ON_SYS_ERROR*() that can return and leave the regular functions marked __noreturn__.
The branch coverage exclusion rules were overly broad and included functions that ended in a capital letter, which disabled all coverage for the statement. Improve matching so that all characters in the name must be upper-case for a match.
Some macros with internal branches accepted parameters that might contain conditionals. This made it impossible to tell which branches belonged to which, and in any case an overzealous exclusion rule was ignoring all branches in such cases. Add the DEBUG_COVERAGE flag to build a modified version of the macros without any internal branches to be used for coverage testing. In most cases, the branches were optimizations (like checking logWill()) that improve production performance but are not needed for testing. In other cases, a parameter needed to be added to the underlying function to handle the branch during coverage testing.
Also tweak the coverage rules so that macros without conditionals are automatically excluded from branch coverage as long as they are not themselves a parameter.
Finally, update tests and code where missing coverage was exposed by these changes. Some code was updated to remove existing coverage exclusions when it was a simple change.
Some functions (e.g. getpwnam()/getgrnam()) will return an error but not set errno. In this case there's no use in appending strerror(), which will be "Success". This is confusing since an error has just been reported.
At least in the examples above, an error with no errno set just means "missing" and our current error message already conveys that.
There was a lot of extra boilerplate involved in setting up pipes so that is now automated.
In some cases testing with multiple children is useful so allow that as well.
The prior behavior was to throw an exception but this was not very helpful when something unexpected happened. Better to at least emit the error message even if the error code is not very helpful.
Improve on 7794ab50 by including the build flag files directly into the Makefile as dependencies (even though they are not includes). This simplifies some of the rsync logic and allows make to do what it does best.
Also split build flag files into test, harness, and build to reduce rebuilds. Test flags are used to build test.c, harness flags are used to build the rest of the files in the test harness, and build flags are used for the files that are not directly involved in testing.
Low-level functions only include stack trace in test builds while higher-level functions ship with stack trace built-in. Stack traces include all parameters passed to the function but production builds only create the parameter list when the log level is set high enough, i.e. debug or trace depending on the function.
