# [PATCH v2 1/1] trace2: NULL is not allowed for va_list 2 messages from 2019-03-19 to 2019-03-19. Participants: tboegi@web.de, Jeff Hostetler. Thread: https://gitlist.dev/t/50779 ## tboegi@web.de, 2019-03-19 17:13 Subject: [PATCH v2 1/1] trace2: NULL is not allowed for va_list Message-ID: <20190319171347.7677-1-tboegi@web.de> URL: https://gitlist.dev/e/20190319171347.7677-1-tboegi%40web.de In-Reply-To: <20190316104616.27085-1-tboegi@web.de> ``` From: Torsten Bögershausen Some compilers don't allow NULL to be passed for a va_list, and e.g. "gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516" errors out like this: trace2/tr2_tgt_event.c:193:18: error: invalid operands to binary && (have ‘int’ and ‘va_list {aka __va_list}’) if (fmt && *fmt && ap) { ^^ I couldn't find any hints that va_list and pointers can be mixed, and no hints that they can't either. Morten Welinder comments: "C99, Section 7.15, simply says that va_list "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... The portable solution is to use "va_list" everywhere in the callchain. As a consequence, both trace2_region_enter_fl() and trace2_region_leave_fl() now take a variable argument list. Signed-off-by: Torsten Bögershausen --- 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 ``` ## Jeff Hostetler, 2019-03-19 18:03 Subject: Re: [PATCH v2 1/1] trace2: NULL is not allowed for va_list Message-ID: <1899eb63-c986-6c18-d09e-9b1584f471d0@jeffhostetler.com> URL: https://gitlist.dev/e/1899eb63-c986-6c18-d09e-9b1584f471d0%40jeffhostetler.com In-Reply-To: <20190319171347.7677-1-tboegi@web.de> ``` On 3/19/2019 1:13 PM, tboegi@web.de wrote: > From: Torsten Bögershausen > > Some compilers don't allow NULL to be passed for a va_list, > and e.g. "gcc (Raspbian 6.3.0-18+rpi1+deb9u1) 6.3.0 20170516" > errors out like this: > trace2/tr2_tgt_event.c:193:18: > error: invalid operands to binary && > (have ‘int’ and ‘va_list {aka __va_list}’) > if (fmt && *fmt && ap) { > ^^ > I couldn't find any hints that va_list and pointers can be mixed, > and no hints that they can't either. Morten Welinder comments: > > "C99, Section 7.15, simply says that va_list "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... > > The portable solution is to use "va_list" everywhere in the callchain. > As a consequence, both trace2_region_enter_fl() and trace2_region_leave_fl() > now take a variable argument list. > > Signed-off-by: Torsten Bögershausen Looks good. Thanks for tracking this down. Jeff Signed-off-by: Jeff Hostetler ```