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

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

[Cyril Hrubis]

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
message on a short read() while developing tests.

Reported-by: Andrea Cervesato <andrea.cervesato@suse.com>
Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 lib/safe_macros.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lib/safe_macros.c b/lib/safe_macros.c
index 109268587..b224a5861 100644
--- a/lib/safe_macros.c
+++ b/lib/safe_macros.c
@@ -293,7 +293,7 @@ ssize_t safe_read(const char *file, const int lineno, void (*cleanup_fn) (void),
 
 	rval = read(fildes, buf, nbyte);
 
-	if (rval == -1 || (len_strict && (size_t)rval != nbyte)) {
+	if (rval == -1) {
 		tst_brkm_(file, lineno, TBROK | TERRNO, cleanup_fn,
 			"read(%d,%p,%zu) failed, returned %zd", fildes, buf,
 			nbyte, rval);
@@ -301,6 +301,10 @@ ssize_t safe_read(const char *file, const int lineno, void (*cleanup_fn) (void),
 		tst_brkm_(file, lineno, TBROK | TERRNO, cleanup_fn,
 			"Invalid read(%d,%p,%zu) return value %zd", fildes,
 			buf, nbyte, rval);
+	} else if (len_strict && (size_t)rval != nbyte) {
+		tst_brkm_(file, lineno, TBROK, cleanup_fn,
+			  "Short read(%d,%p,%zu) returned only %zd",
+			  fildes, buf, nbyte, rval);
 	}
 
 	return rval;
-- 
2.45.2


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

[Petr Vorel]

Hi Cyril, Andrea
> 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>

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);

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Re: [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

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

[Petr Vorel]

Hi Cyril,

> 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;
>                 }

Reviewed-by: Petr Vorel <pvorel@suse.cz>

Please merge it directly (ideally with link to this discussion on lore).

Kind regards,
Petr

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

[Cyril Hrubis]

Hi!
> Reviewed-by: Petr Vorel <pvorel@suse.cz>
> 
> Please merge it directly (ideally with link to this discussion on lore).

Done, thanks.

-- 
Cyril Hrubis
chrubis@suse.cz

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