[PATCH v3] tools/xenpmd: Fix gcc10 snprintf warning

Bertrand Marquis posted 1 patch 2 weeks ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/xen tags/patchew/14ac4900dcf4fb9b45ce4f5e3d60de7f7e3602ab.1602753323.git.bertrand.marquis@arm.com
Maintainers: Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>
tools/xenpmd/xenpmd.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

[PATCH v3] tools/xenpmd: Fix gcc10 snprintf warning

Posted by Bertrand Marquis 2 weeks ago
Add a check for snprintf return code and ignore the entry if we get an
error. This should in fact never happen and is more a trick to make gcc
happy and prevent compilation errors.

This is solving the following gcc warning when compiling for arm32 host
platforms with optimization activated:
xenpmd.c:92:37: error: '%s' directive output may be truncated writing
between 4 and 2147483645 bytes into a region of size 271
[-Werror=format-truncation=]

This is also solving the following Debian bug:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=970802

Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
---
 tools/xenpmd/xenpmd.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/tools/xenpmd/xenpmd.c b/tools/xenpmd/xenpmd.c
index 35fd1c931a..12b82cf43e 100644
--- a/tools/xenpmd/xenpmd.c
+++ b/tools/xenpmd/xenpmd.c
@@ -102,6 +102,7 @@ FILE *get_next_battery_file(DIR *battery_dir,
     FILE *file = 0;
     struct dirent *dir_entries;
     char file_name[284];
+    int ret;
     
     do 
     {
@@ -111,11 +112,15 @@ FILE *get_next_battery_file(DIR *battery_dir,
         if ( strlen(dir_entries->d_name) < 4 )
             continue;
         if ( battery_info_type == BIF ) 
-            snprintf(file_name, sizeof(file_name), BATTERY_INFO_FILE_PATH,
+            ret = snprintf(file_name, sizeof(file_name), BATTERY_INFO_FILE_PATH,
                      dir_entries->d_name);
         else 
-            snprintf(file_name, sizeof(file_name), BATTERY_STATE_FILE_PATH,
+            ret = snprintf(file_name, sizeof(file_name), BATTERY_STATE_FILE_PATH,
                      dir_entries->d_name);
+        /* This should not happen but is needed to pass gcc checks */
+        if (ret < 0)
+            continue;
+        file_name[sizeof(file_name) - 1] = '\0';
         file = fopen(file_name, "r");
     } while ( !file );
 
-- 
2.17.1


Re: [PATCH v3] tools/xenpmd: Fix gcc10 snprintf warning

Posted by Wei Liu 2 weeks ago
On Thu, Oct 15, 2020 at 10:16:09AM +0100, Bertrand Marquis wrote:
> Add a check for snprintf return code and ignore the entry if we get an
> error. This should in fact never happen and is more a trick to make gcc
> happy and prevent compilation errors.
> 
> This is solving the following gcc warning when compiling for arm32 host
> platforms with optimization activated:
> xenpmd.c:92:37: error: '%s' directive output may be truncated writing
> between 4 and 2147483645 bytes into a region of size 271
> [-Werror=format-truncation=]
> 
> This is also solving the following Debian bug:
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=970802
> 
> Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>

Acked-by: Wei Liu <wl@xen.org>

Re: [PATCH v3] tools/xenpmd: Fix gcc10 snprintf warning

Posted by Bertrand Marquis 2 weeks ago

> On 16 Oct 2020, at 14:28, Wei Liu <wl@xen.org> wrote:
> 
> On Thu, Oct 15, 2020 at 10:16:09AM +0100, Bertrand Marquis wrote:
>> Add a check for snprintf return code and ignore the entry if we get an
>> error. This should in fact never happen and is more a trick to make gcc
>> happy and prevent compilation errors.
>> 
>> This is solving the following gcc warning when compiling for arm32 host
>> platforms with optimization activated:
>> xenpmd.c:92:37: error: '%s' directive output may be truncated writing
>> between 4 and 2147483645 bytes into a region of size 271
>> [-Werror=format-truncation=]
>> 
>> This is also solving the following Debian bug:
>> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=970802
>> 
>> Signed-off-by: Bertrand Marquis <bertrand.marquis@arm.com>
> 
> Acked-by: Wei Liu <wl@xen.org>

Thanks :-)

Bertrand