[PATCH v1 1/1] trace2: NULL is not allowed for va_list

[PATCH v1 1/1] trace2: NULL is not allowed for va_list

[tboegi]

From: Torsten Bögershausen <tboegi@web.de>

Some compilers don't allow NULL to be passed for a va_list.
Use va_list instead.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---
 trace2.c                | 15 +++++++++++----
 trace2.h                |  4 ++--
 trace2/tr2_tgt_event.c  |  2 +-
 trace2/tr2_tgt_normal.c |  2 +-
 trace2/tr2_tgt_perf.c   |  2 +-
 5 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/trace2.c b/trace2.c
index ccccd4ef09..8bbad56887 100644
--- a/trace2.c
+++ b/trace2.c
@@ -548,10 +548,14 @@ void trace2_region_enter_printf_va_fl(const char *file, int line,
 }

 void trace2_region_enter_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo)
+			    const char *label, const struct repository *repo, ...)
 {
+	va_list ap;
+	va_start(ap, repo);
 	trace2_region_enter_printf_va_fl(file, line, category, label, repo,
-					 NULL, NULL);
+					 NULL, ap);
+	va_end(ap);
+
 }

 void trace2_region_enter_printf_fl(const char *file, int line,
@@ -621,10 +625,13 @@ void trace2_region_leave_printf_va_fl(const char *file, int line,
 }

 void trace2_region_leave_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo)
+			    const char *label, const struct repository *repo, ...)
 {
+	va_list ap;
+	va_start(ap, repo);
 	trace2_region_leave_printf_va_fl(file, line, category, label, repo,
-					 NULL, NULL);
+					 NULL, ap);
+	va_end(ap);
 }

 void trace2_region_leave_printf_fl(const char *file, int line,
diff --git a/trace2.h b/trace2.h
index ae5020d0e6..b330a54a89 100644
--- a/trace2.h
+++ b/trace2.h
@@ -238,7 +238,7 @@ void trace2_def_repo_fl(const char *file, int line, struct repository *repo);
  * on this thread.
  */
 void trace2_region_enter_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo);
+			    const char *label, const struct repository *repo, ...);

 #define trace2_region_enter(category, label, repo) \
 	trace2_region_enter_fl(__FILE__, __LINE__, (category), (label), (repo))
@@ -278,7 +278,7 @@ void trace2_region_enter_printf(const char *category, const char *label,
  * in this nesting level.
  */
 void trace2_region_leave_fl(const char *file, int line, const char *category,
-			    const char *label, const struct repository *repo);
+			    const char *label, const struct repository *repo, ...);

 #define trace2_region_leave(category, label, repo) \
 	trace2_region_leave_fl(__FILE__, __LINE__, (category), (label), (repo))
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 107cb5317d..1cf4f62441 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -190,7 +190,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
 static void maybe_add_string_va(struct json_writer *jw, const char *field_name,
 				const char *fmt, va_list ap)
 {
-	if (fmt && *fmt && ap) {
+	if (fmt && *fmt) {
 		va_list copy_ap;
 		struct strbuf buf = STRBUF_INIT;

diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index 547183d5b6..1a07d70abd 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -126,7 +126,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
 static void maybe_append_string_va(struct strbuf *buf, const char *fmt,
 				   va_list ap)
 {
-	if (fmt && *fmt && ap) {
+	if (fmt && *fmt) {
 		va_list copy_ap;

 		va_copy(copy_ap, ap);
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index f0746fcf86..2a866d701b 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -211,7 +211,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
 static void maybe_append_string_va(struct strbuf *buf, const char *fmt,
 				   va_list ap)
 {
-	if (fmt && *fmt && ap) {
+	if (fmt && *fmt) {
 		va_list copy_ap;

 		va_copy(copy_ap, ap);
--
2.21.0.135.g6e0cc67761

Re: [PATCH v1 1/1] trace2: NULL is not allowed for va_list

[Junio C Hamano]

tboegi@web.de writes:

> From: Torsten Bögershausen <tboegi@web.de>
>
> Some compilers don't allow NULL to be passed for a va_list.
> Use va_list instead.

Wow (I seem to be keep saying this today).

>
> Signed-off-by: Torsten Bögershausen <tboegi@web.de>
> ---
>  trace2.c                | 15 +++++++++++----
>  trace2.h                |  4 ++--
>  trace2/tr2_tgt_event.c  |  2 +-
>  trace2/tr2_tgt_normal.c |  2 +-
>  trace2/tr2_tgt_perf.c   |  2 +-
>  5 files changed, 16 insertions(+), 9 deletions(-)
>
> diff --git a/trace2.c b/trace2.c
> index ccccd4ef09..8bbad56887 100644
> --- a/trace2.c
> +++ b/trace2.c
> @@ -548,10 +548,14 @@ void trace2_region_enter_printf_va_fl(const char *file, int line,
>  }
>
>  void trace2_region_enter_fl(const char *file, int line, const char *category,
> -			    const char *label, const struct repository *repo)
> +			    const char *label, const struct repository *repo, ...)
>  {
> +	va_list ap;
> +	va_start(ap, repo);
>  	trace2_region_enter_printf_va_fl(file, line, category, label, repo,
> -					 NULL, NULL);
> +					 NULL, ap);
> +	va_end(ap);
> +
>  }
>
>  void trace2_region_enter_printf_fl(const char *file, int line,
> @@ -621,10 +625,13 @@ void trace2_region_leave_printf_va_fl(const char *file, int line,
>  }
>
>  void trace2_region_leave_fl(const char *file, int line, const char *category,
> -			    const char *label, const struct repository *repo)
> +			    const char *label, const struct repository *repo, ...)
>  {
> +	va_list ap;
> +	va_start(ap, repo);
>  	trace2_region_leave_printf_va_fl(file, line, category, label, repo,
> -					 NULL, NULL);
> +					 NULL, ap);
> +	va_end(ap);
>  }
>
>  void trace2_region_leave_printf_fl(const char *file, int line,
> diff --git a/trace2.h b/trace2.h
> index ae5020d0e6..b330a54a89 100644
> --- a/trace2.h
> +++ b/trace2.h
> @@ -238,7 +238,7 @@ void trace2_def_repo_fl(const char *file, int line, struct repository *repo);
>   * on this thread.
>   */
>  void trace2_region_enter_fl(const char *file, int line, const char *category,
> -			    const char *label, const struct repository *repo);
> +			    const char *label, const struct repository *repo, ...);
>
>  #define trace2_region_enter(category, label, repo) \
>  	trace2_region_enter_fl(__FILE__, __LINE__, (category), (label), (repo))
> @@ -278,7 +278,7 @@ void trace2_region_enter_printf(const char *category, const char *label,
>   * in this nesting level.
>   */
>  void trace2_region_leave_fl(const char *file, int line, const char *category,
> -			    const char *label, const struct repository *repo);
> +			    const char *label, const struct repository *repo, ...);
>
>  #define trace2_region_leave(category, label, repo) \
>  	trace2_region_leave_fl(__FILE__, __LINE__, (category), (label), (repo))
> diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
> index 107cb5317d..1cf4f62441 100644
> --- a/trace2/tr2_tgt_event.c
> +++ b/trace2/tr2_tgt_event.c
> @@ -190,7 +190,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
>  static void maybe_add_string_va(struct json_writer *jw, const char *field_name,
>  				const char *fmt, va_list ap)
>  {
> -	if (fmt && *fmt && ap) {
> +	if (fmt && *fmt) {
>  		va_list copy_ap;
>  		struct strbuf buf = STRBUF_INIT;
>
> diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
> index 547183d5b6..1a07d70abd 100644
> --- a/trace2/tr2_tgt_normal.c
> +++ b/trace2/tr2_tgt_normal.c
> @@ -126,7 +126,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
>  static void maybe_append_string_va(struct strbuf *buf, const char *fmt,
>  				   va_list ap)
>  {
> -	if (fmt && *fmt && ap) {
> +	if (fmt && *fmt) {
>  		va_list copy_ap;
>
>  		va_copy(copy_ap, ap);
> diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
> index f0746fcf86..2a866d701b 100644
> --- a/trace2/tr2_tgt_perf.c
> +++ b/trace2/tr2_tgt_perf.c
> @@ -211,7 +211,7 @@ static void fn_atexit(uint64_t us_elapsed_absolute, int code)
>  static void maybe_append_string_va(struct strbuf *buf, const char *fmt,
>  				   va_list ap)
>  {
> -	if (fmt && *fmt && ap) {
> +	if (fmt && *fmt) {
>  		va_list copy_ap;
>
>  		va_copy(copy_ap, ap);
> --
> 2.21.0.135.g6e0cc67761

Re: [PATCH v1 1/1] trace2: NULL is not allowed for va_list

[Jeff Hostetler]

On 3/16/2019 6:47 AM, tboegi@web.de wrote:
> From: Torsten Bögershausen <tboegi@web.de>
> 
> Some compilers don't allow NULL to be passed for a va_list.
> Use va_list instead.
> 
> Signed-off-by: Torsten Bögershausen <tboegi@web.de>

Thanks for the fixup.

For future reference, can you elaborate on which compiler
and/or platform has the problem ?

Jeff

Re: [PATCH v1 1/1] trace2: NULL is not allowed for va_list

[Torsten Bögershausen]

On Mon, Mar 18, 2019 at 08:35:26AM -0400, Jeff Hostetler wrote:
>
>
> On 3/16/2019 6:47 AM, tboegi@web.de wrote:
> > From: Torsten Bögershausen <tboegi@web.de>
> >
> > Some compilers don't allow NULL to be passed for a va_list.
> > Use va_list instead.
> >
> > Signed-off-by: Torsten Bögershausen <tboegi@web.de>
>
> Thanks for the fixup.
>
> For future reference, can you elaborate on which compiler
> and/or platform has the problem ?
>
> Jeff

It is on a Raspberry PI:
gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516

trace2/tr2_tgt_event.c:193:18: error: invalid operands to binary && (have ‘int’ and ‘va_list {aka __va_list}’)
  if (fmt && *fmt && ap) {
        ~~~~~~~~~~~ ^~

(And I couldn't find any hints that va_list and pointers can be mixed,
 and no hints that they can't either)

Re: [PATCH v1 1/1] trace2: NULL is not allowed for va_list

[Morten Welinder]

> And I couldn't find any hints that va_list and pointers can be mixed,
> and no hints that they can't either

C99, Section 7.15, simply says that it "is an object type suitable for
holding information needed by the macros va_start, va_end, and
va_copy".

So clearly not guaranteed to be mixable with pointers.  And not
prohibited from being mixable either, for that matter.
And, nit-pickingly, NULL might be a valid value representing some
sequence of arguments if the two are mixable.

M.