[PATCH v2] Ensure mktime sets errno on error (bug 23789)

[Joseph Myers]

On Sun, 28 Oct 2018, Albert ARIBAUD (3ADEV) wrote:

> +#define TEST_FUNCTION do_test ()
> +#include "../test-skeleton.c"

New tests should use <support/test-driver.c>, not the old test-skeleton.

> +  if (result == -1 && errno == 0)
> +    return result;

It is never OK for a library function to set errno to 0 (return with errno 
set to 0 when it wasn't 0 on entry); if there is no error you can restore 
the value that was set on entry to mktime, or set errno to some spurious 
other value despite the lack of an error (maybe not a good idea in this 
case, because it prevents callers from distinguishing error and non-error 
-1), but not set it to 0 if it wasn't 0 on entry to the library function.  
(See ISO C: "The value of errno in the initial thread is zero at program 
startup (the initial value of errno in other threads is an indeterminate 
value), but is never set to zero by any library function.".)

> +    __set_errno(errno_from_tzset);

Missing space before '(', here and elsewhere in this patch.

-- 
Joseph S. Myers
joseph@codesourcery.com