[PATCH v2] tools/perf: Fix malloc call for new -Walloc-size

[PATCH v2] tools/perf: Fix malloc call for new -Walloc-size

[Yanteng Si]

From: Sun Haiyong <sunhaiyong@loongson.cn>

GCC 14 introduces a new -Walloc-size included in -Wextra which errors out
like:
```
builtin-top.c: In function ‘prompt_integer’:
builtin-top.c:360:21: error: allocation of insufficient size ‘0’ for
type ‘char’ with size ‘1’ [-Werror=alloc-size]
  360 |         char *buf = malloc(0), *p;
      |                     ^~~~~~

```

So, just set it to NULL, silence this error.

Signed-off-by: Sun Haiyong <sunhaiyong@loongson.cn>
Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
---
v2:

* Refer to Namhyung's comment and set it to NULL.

 tools/perf/builtin-top.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index ea8c7eca5eee..3960c4d15eff 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -357,7 +357,7 @@ static void perf_top__print_sym_table(struct perf_top *top)
 
 static void prompt_integer(int *target, const char *msg)
 {
-	char *buf = malloc(0), *p;
+	char *buf = NULL, *p;
 	size_t dummy = 0;
 	int tmp;
 
-- 
2.31.4

Re: [PATCH v2] tools/perf: Fix malloc call for new -Walloc-size

[Arnaldo Carvalho de Melo]

Em Mon, Dec 04, 2023 at 04:20:55PM +0800, Yanteng Si escreveu:
> From: Sun Haiyong <sunhaiyong@loongson.cn>
> 
> GCC 14 introduces a new -Walloc-size included in -Wextra which errors out
> like:
> ```
> builtin-top.c: In function ‘prompt_integer’:
> builtin-top.c:360:21: error: allocation of insufficient size ‘0’ for
> type ‘char’ with size ‘1’ [-Werror=alloc-size]
>   360 |         char *buf = malloc(0), *p;
>       |                     ^~~~~~
> 
> ```
> 
> So, just set it to NULL, silence this error.

Thanks, applied to perf-tools.

Changed the subject to:

  perf top: Remove needless malloc(0) call that triggers -Walloc-size

And the last line of the log to:

  Just set it to NULL, getline() will do the allocation.

- Arnaldo

 
> Signed-off-by: Sun Haiyong <sunhaiyong@loongson.cn>
> Signed-off-by: Yanteng Si <siyanteng@loongson.cn>
> ---
> v2:
> 
> * Refer to Namhyung's comment and set it to NULL.
> 
>  tools/perf/builtin-top.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
> index ea8c7eca5eee..3960c4d15eff 100644
> --- a/tools/perf/builtin-top.c
> +++ b/tools/perf/builtin-top.c
> @@ -357,7 +357,7 @@ static void perf_top__print_sym_table(struct perf_top *top)
>  
>  static void prompt_integer(int *target, const char *msg)
>  {
> -	char *buf = malloc(0), *p;
> +	char *buf = NULL, *p;
>  	size_t dummy = 0;
>  	int tmp;
>  
> -- 
> 2.31.4
> 

-- 

- Arnaldo