Re: [PATCH 01/10] scripts/basic/bin2c: Complete error handling in main()

[Masahiro Yamada]

2016-10-28 17:31 GMT+09:00 SF Markus Elfring :
> From: Markus Elfring 
> Date: Thu, 27 Oct 2016 16:15:04 +0200
>
> Return values were not checked from five calls of the function "printf".
>
> This issue was detected also by using the Coccinelle software.
>
>
> * Add a bit of exception handling there.
>
> * Optimise this function implementation a bit.
>
>   - Replace two output calls with the functions "fputs" and "puts".
>
>   - Use the preincrement operator for the variable "total".
>
> Signed-off-by: Markus Elfring 
> ---
>  scripts/basic/bin2c.c | 26 --
>  1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/basic/bin2c.c b/scripts/basic/bin2c.c
> index c3d7eef..c6c8860 100644
> --- a/scripts/basic/bin2c.c
> +++ b/scripts/basic/bin2c.c
> @@ -8,29 +8,35 @@
>   */
>
>  #include 
> +#include 
>
>  int main(int argc, char *argv[])
>  {
> int ch, total = 0;
>
> if (argc > 1)
> -   printf("const char %s[] %s=\n",
> -   argv[1], argc > 2 ? argv[2] : "");
> +   if (printf("const char %s[] %s=\n",
> +  argv[1], argc > 2 ? argv[2] : "") < 16)
> +   return errno;
>
> do {
> -   printf("\t\"");
> +   if (fputs("\t\"", stdout) < 0)
> +   return errno;
> +
> while ((ch = getchar()) != EOF) {
> -   total++;
> -   printf("\\x%02x", ch);
> -   if (total % 16 == 0)
> +   if (printf("\\x%02x", ch) < 4)
> +   return errno;
> +   if (++total % 16 == 0)
> break;
> }
> -   printf("\"\n");
> +
> +   if (puts("\"") < 0)
> +   return errno;


Is replacing printf("\"\n") with puts("\"") optimization?


Frankly, the result of this patch
seems extremely unreadable code.


-- 
Best Regards
Masahiro Yamada

Re: [PATCH 01/10] scripts/basic/bin2c: Complete error handling in main()

[Masahiro Yamada]

2016-10-28 17:31 GMT+09:00 SF Markus Elfring :
> From: Markus Elfring 
> Date: Thu, 27 Oct 2016 16:15:04 +0200
>
> Return values were not checked from five calls of the function "printf".
>
> This issue was detected also by using the Coccinelle software.
>
>
> * Add a bit of exception handling there.
>
> * Optimise this function implementation a bit.
>
>   - Replace two output calls with the functions "fputs" and "puts".
>
>   - Use the preincrement operator for the variable "total".
>
> Signed-off-by: Markus Elfring 
> ---
>  scripts/basic/bin2c.c | 26 --
>  1 file changed, 16 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/basic/bin2c.c b/scripts/basic/bin2c.c
> index c3d7eef..c6c8860 100644
> --- a/scripts/basic/bin2c.c
> +++ b/scripts/basic/bin2c.c
> @@ -8,29 +8,35 @@
>   */
>
>  #include 
> +#include 
>
>  int main(int argc, char *argv[])
>  {
> int ch, total = 0;
>
> if (argc > 1)
> -   printf("const char %s[] %s=\n",
> -   argv[1], argc > 2 ? argv[2] : "");
> +   if (printf("const char %s[] %s=\n",
> +  argv[1], argc > 2 ? argv[2] : "") < 16)
> +   return errno;
>
> do {
> -   printf("\t\"");
> +   if (fputs("\t\"", stdout) < 0)
> +   return errno;
> +
> while ((ch = getchar()) != EOF) {
> -   total++;
> -   printf("\\x%02x", ch);
> -   if (total % 16 == 0)
> +   if (printf("\\x%02x", ch) < 4)
> +   return errno;
> +   if (++total % 16 == 0)
> break;
> }
> -   printf("\"\n");
> +
> +   if (puts("\"") < 0)
> +   return errno;


Is replacing printf("\"\n") with puts("\"") optimization?


Frankly, the result of this patch
seems extremely unreadable code.


-- 
Best Regards
Masahiro Yamada

Re: [PATCH 01/10] scripts/basic/bin2c: Complete error handling in main()

[Jim Davis]

On Fri, Oct 28, 2016 at 1:31 AM, SF Markus Elfring
 wrote:
> From: Markus Elfring 
> Date: Thu, 27 Oct 2016 16:15:04 +0200
>
> Return values were not checked from five calls of the function "printf".
>
> This issue was detected also by using the Coccinelle software.
>
>
> * Add a bit of exception handling there.
>
> * Optimise this function implementation a bit.

The most interesting thing about this patch was trying to figure out
how to actually get bin2c to run at all.  Making a defconfig kernel
didn't run it.  Making a kernel with the latest Ubuntu 16.10 config
file didn't run it.  Setting CONFIG_IKCONFIG runs it (once), for the
folks who want to use scripts/extract-ikconfig.  After that, if you
dig about in the makefiles, it looks like you have to turn on the
Tomoyo LSM -- which doesn't seem to be a common occurrence -- or else
set CONFIG_KEXEC_FILE to generate the 'purgatory' thing it uses.
Again, not the most frequent of events, as far as I can tell.

Given how uncommon running bin2c seems to be, "optimizing" it may not
be a useful project.

-- 
Jim

Re: [PATCH 01/10] scripts/basic/bin2c: Complete error handling in main()

[Jim Davis]

On Fri, Oct 28, 2016 at 1:31 AM, SF Markus Elfring
 wrote:
> From: Markus Elfring 
> Date: Thu, 27 Oct 2016 16:15:04 +0200
>
> Return values were not checked from five calls of the function "printf".
>
> This issue was detected also by using the Coccinelle software.
>
>
> * Add a bit of exception handling there.
>
> * Optimise this function implementation a bit.

The most interesting thing about this patch was trying to figure out
how to actually get bin2c to run at all.  Making a defconfig kernel
didn't run it.  Making a kernel with the latest Ubuntu 16.10 config
file didn't run it.  Setting CONFIG_IKCONFIG runs it (once), for the
folks who want to use scripts/extract-ikconfig.  After that, if you
dig about in the makefiles, it looks like you have to turn on the
Tomoyo LSM -- which doesn't seem to be a common occurrence -- or else
set CONFIG_KEXEC_FILE to generate the 'purgatory' thing it uses.
Again, not the most frequent of events, as far as I can tell.

Given how uncommon running bin2c seems to be, "optimizing" it may not
be a useful project.

-- 
Jim