[PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[Zhongze Liu]

GCC 7.1.1 complains that several buffers passed to snprintf() in xenpmd
and tools/ocmal/xc are too small to hold the largest possible resulting string.

enlarge the size of these buffers to fix the warnings.

Signed-off-by: Zhongze Liu <blackskygg@gmail.com>
---
CC: David Scott <dave@recoil.org>
CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>

Changed since v1:
  * Changed the word "error" to "warning" in title and description
  * Enlarge the buffer instead of replacing snprintf() with asprintf()
---
 tools/ocaml/libs/xc/xenctrl_stubs.c | 2 +-
 tools/xenpmd/xenpmd.c               | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/ocaml/libs/xc/xenctrl_stubs.c b/tools/ocaml/libs/xc/xenctrl_stubs.c
index 5e455519d4..f1b28db53a 100644
--- a/tools/ocaml/libs/xc/xenctrl_stubs.c
+++ b/tools/ocaml/libs/xc/xenctrl_stubs.c
@@ -54,7 +54,7 @@
 
 static void Noreturn failwith_xc(xc_interface *xch)
 {
-	char error_str[256];
+	char error_str[1028];
 	if (xch) {
 		const xc_error *error = xc_get_last_error(xch);
 		if (error->code == XC_ERROR_NONE)
diff --git a/tools/xenpmd/xenpmd.c b/tools/xenpmd/xenpmd.c
index b3a31062aa..df96f2683f 100644
--- a/tools/xenpmd/xenpmd.c
+++ b/tools/xenpmd/xenpmd.c
@@ -100,7 +100,7 @@ FILE *get_next_battery_file(DIR *battery_dir,
 {
     FILE *file = 0;
     struct dirent *dir_entries;
-    char file_name[32];
+    char file_name[512];
     
     do 
     {
@@ -110,10 +110,10 @@ FILE *get_next_battery_file(DIR *battery_dir,
         if ( strlen(dir_entries->d_name) < 4 )
             continue;
         if ( battery_info_type == BIF ) 
-            snprintf(file_name, 32, BATTERY_INFO_FILE_PATH,
+	    snprintf(file_name, sizeof(file_name), BATTERY_INFO_FILE_PATH,
                      dir_entries->d_name);
         else 
-            snprintf(file_name, 32, BATTERY_STATE_FILE_PATH,
+            snprintf(file_name, sizeof(file_name), BATTERY_STATE_FILE_PATH,
                      dir_entries->d_name);
         file = fopen(file_name, "r");
     } while ( !file );
-- 
2.13.1


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Re: [PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[Wei Liu]

On Tue, Jun 13, 2017 at 01:51:17AM +0800, Zhongze Liu wrote:
> GCC 7.1.1 complains that several buffers passed to snprintf() in xenpmd
> and tools/ocmal/xc are too small to hold the largest possible resulting string.
> 
> enlarge the size of these buffers to fix the warnings.
> 
> Signed-off-by: Zhongze Liu <blackskygg@gmail.com>

Acked-by: Wei Liu <wei.liu2@citrix.com>

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Re: [PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[Ian Jackson]

Zhongze Liu writes ("[PATCH v2] tools: fix several "format-truncation" warnings with GCC 7"):
> GCC 7.1.1 complains that several buffers passed to snprintf() in
> xenpmd and tools/ocmal/xc are too small to hold the largest possible
> resulting string.
> 
> enlarge the size of these buffers to fix the warnings.

This is probably a reasonable approach.  But, I can't see where you
got the new maximum sizes.  Forgive me if I missed a mail, but I think
at least the commit message should explain how each of the new sizes
is calculated.

Thanks,
Ian.

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Re: [PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[Wei Liu]

On Tue, Jun 13, 2017 at 11:19:58AM +0100, Ian Jackson wrote:
> Zhongze Liu writes ("[PATCH v2] tools: fix several "format-truncation" warnings with GCC 7"):
> > GCC 7.1.1 complains that several buffers passed to snprintf() in
> > xenpmd and tools/ocmal/xc are too small to hold the largest possible
> > resulting string.
> > 
> > enlarge the size of these buffers to fix the warnings.
> 
> This is probably a reasonable approach.  But, I can't see where you
> got the new maximum sizes.  Forgive me if I missed a mail, but I think
> at least the commit message should explain how each of the new sizes
> is calculated.

Zhongze, please summarise what we discussed on IRC, especially the part
we figured out the various buffer sizes, in the commit message.

Ideally you should include the exact error messages in the commit
message, too.

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Re: [PATCH v2] tools: fix several "format-truncation" warnings with GCC 7

[Zhongze Liu]

Hi Wei & Ian,

2017-06-13 18:52 GMT+08:00 Wei Liu <wei.liu2@citrix.com>:
> On Tue, Jun 13, 2017 at 11:19:58AM +0100, Ian Jackson wrote:
>> Zhongze Liu writes ("[PATCH v2] tools: fix several "format-truncation" warnings with GCC 7"):
>> > GCC 7.1.1 complains that several buffers passed to snprintf() in
>> > xenpmd and tools/ocmal/xc are too small to hold the largest possible
>> > resulting string.
>> >
>> > enlarge the size of these buffers to fix the warnings.
>>
>> This is probably a reasonable approach.  But, I can't see where you
>> got the new maximum sizes.  Forgive me if I missed a mail, but I think
>> at least the commit message should explain how each of the new sizes
>> is calculated.

OK, I'll add that.

>
> Zhongze, please summarise what we discussed on IRC, especially the part
> we figured out the various buffer sizes, in the commit message.
>
> Ideally you should include the exact error messages in the commit
> message, too.

Will do.

Cheers,

Zhongze Liu

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