[PATCH 4/5] trace: handle the empty string in a sensible way

[PATCH 4/5] trace: handle the empty string in a sensible way

[Kris Van Hees]

The trace("") action would dump a series of 0x00 bytes (strsize of
them) rather than printing an empty string.  While that is the legacy
behaviour, it does not really make any sense to do so.  The trace
action is described as printing data as a string if possible, and a
block of 0-bytes can certainly be printed as an empty string.

Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
---
 libdtrace/dt_consume.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libdtrace/dt_consume.c b/libdtrace/dt_consume.c
index edfe5bbae..2dce69d6d 100644
--- a/libdtrace/dt_consume.c
+++ b/libdtrace/dt_consume.c
@@ -991,7 +991,7 @@ dt_print_bytes(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
 		    c[i] == '\b' || c[i] == '\a')
 			continue;
 
-		if (c[i] == '\0' && i > 0) {
+		if (c[i] == '\0') {
 			/*
 			 * This looks like it might be a string.  Before we
 			 * assume that it is indeed a string, check the
-- 
2.45.2

Re: [DTrace-devel] [PATCH 4/5] trace: handle the empty string in a sensible way

[Eugene Loh]

I agree, but does this change any test results?  If not, should there be 
a test added?

On 8/13/25 11:57, Kris Van Hees via DTrace-devel wrote:
> The trace("") action would dump a series of 0x00 bytes (strsize of
> them) rather than printing an empty string.  While that is the legacy
> behaviour, it does not really make any sense to do so.  The trace
> action is described as printing data as a string if possible, and a
> block of 0-bytes can certainly be printed as an empty string.
>
> Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
> ---
>   libdtrace/dt_consume.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libdtrace/dt_consume.c b/libdtrace/dt_consume.c
> index edfe5bbae..2dce69d6d 100644
> --- a/libdtrace/dt_consume.c
> +++ b/libdtrace/dt_consume.c
> @@ -991,7 +991,7 @@ dt_print_bytes(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
>   		    c[i] == '\b' || c[i] == '\a')
>   			continue;
>   
> -		if (c[i] == '\0' && i > 0) {
> +		if (c[i] == '\0') {
>   			/*
>   			 * This looks like it might be a string.  Before we
>   			 * assume that it is indeed a string, check the

Re: [DTrace-devel] [PATCH 4/5] trace: handle the empty string in a sensible way

[Kris Van Hees]

On Thu, Aug 14, 2025 at 12:18:42PM -0400, Eugene Loh wrote:
> I agree, but does this change any test results?  If not, should there be a
> test added?

Hm, it did at some point in my testing (which is why I added this patch), but
now I do not have that same effect, so I think that perhaps another change I
was making interfered.  So, I will add a test and post v2.

> On 8/13/25 11:57, Kris Van Hees via DTrace-devel wrote:
> > The trace("") action would dump a series of 0x00 bytes (strsize of
> > them) rather than printing an empty string.  While that is the legacy
> > behaviour, it does not really make any sense to do so.  The trace
> > action is described as printing data as a string if possible, and a
> > block of 0-bytes can certainly be printed as an empty string.
> > 
> > Signed-off-by: Kris Van Hees <kris.van.hees@oracle.com>
> > ---
> >   libdtrace/dt_consume.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/libdtrace/dt_consume.c b/libdtrace/dt_consume.c
> > index edfe5bbae..2dce69d6d 100644
> > --- a/libdtrace/dt_consume.c
> > +++ b/libdtrace/dt_consume.c
> > @@ -991,7 +991,7 @@ dt_print_bytes(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
> >   		    c[i] == '\b' || c[i] == '\a')
> >   			continue;
> > -		if (c[i] == '\0' && i > 0) {
> > +		if (c[i] == '\0') {
> >   			/*
> >   			 * This looks like it might be a string.  Before we
> >   			 * assume that it is indeed a string, check the