[LTP] [PATCH] safe_macros: Fix confusing safe_read() failure output

[Cyril Hrubis]

Hi!
> > In the case that we read() less bytes than expected in the strict mode
> > we used the same tst_brk() as for the case when read() fails. However
> > for short reads the errno is in an udefined state and we possibly end up
> > with confusing TBROK message. Andrea reported EACESS ernno in the TBROK
> nit: s/ernno/errno/
> 
> > message on a short read() while developing tests.
> 
> Good catch!
> 
> Reviewed-by: Petr Vorel <pvorel@suse.cz>

Pushed, thanks.

> FYI safe_write() also has TERRNO in len_strict.
> 
> Kind regards,
> Petr
> 
> +++ lib/safe_macros.c
> @@ -554,7 +554,7 @@ ssize_t safe_write(const char *file, const int lineno, void (cleanup_fn) (void),
>  
>  		if (len_strict == SAFE_WRITE_ALL) {
>  			if ((size_t)rval != nbyte)
> -				tst_brkm_(file, lineno, TBROK | TERRNO,
> +				tst_brkm_(file, lineno, TBROK,
>  					cleanup_fn, "short write(%d,%p,%zu) "
>  					"return value %zd",
>  					fildes, buf, nbyte, rval);

I guess that we are missing check for invalid return value from write()
as well and return in the rval == -1 branch, we probably need to add:

diff --git a/lib/safe_macros.c b/lib/safe_macros.c
index b224a5861..3d3e7c693 100644
--- a/lib/safe_macros.c
+++ b/lib/safe_macros.c
@@ -551,6 +551,14 @@ ssize_t safe_write(const char *file, const int lineno, void (cleanup_fn) (void),
                        tst_brkm_(file, lineno, TBROK | TERRNO,
                                cleanup_fn, "write(%d,%p,%zu) failed",
                                fildes, buf, nbyte);
+                       return rval;
+               }
+
+               if (rval < 0) {
+                       tst_brkm_(file, lineno, TBROK, cleanup_fn,
+                                 "invalid write() return value %zi",
+                                 rval);
+                       return rval;
                }


-- 
Cyril Hrubis
chrubis@suse.cz