[PATCH] examples/vm_power: fix format-truncation warning

[PATCH] examples/vm_power: fix format-truncation warning

[Kevin Traynor]

Without libbsd-devel strlcpy is defined as rte_strlcpy and a warning is
raised for format-truncation. Observed with gcc 15.2.1.

In function ‘rte_strlcpy’,
    inlined from ‘add_host_channels’ at
../examples/vm_power_manager/channel_manager.c:600:3:
../lib/eal/include/rte_string_fns.h:63:24:
warning: ‘%s’ directive output may be truncated writing up to
4095 bytes into a region of size 108 [-Wformat-truncation=]
63 |         return (size_t)snprintf(dst, size, "%s", src);
   |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Check for truncation of socket_path[4096] into channel_path[108] to
remove warning.

Cc: stable@dpdk.org

Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
---
 examples/vm_power_manager/channel_manager.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/examples/vm_power_manager/channel_manager.c b/examples/vm_power_manager/channel_manager.c
index 7d7efdd05a..b69449c61d 100644
--- a/examples/vm_power_manager/channel_manager.c
+++ b/examples/vm_power_manager/channel_manager.c
@@ -561,4 +561,5 @@ add_host_channels(void)
 	struct core_info *ci;
 	struct channel_info *chan_infos[RTE_MAX_LCORE];
+	size_t channel_path_size;
 	int i;
 
@@ -598,6 +599,13 @@ add_host_channels(void)
 		}
 		chan_infos[i] = chan_info;
-		strlcpy(chan_info->channel_path, socket_path,
-				sizeof(chan_info->channel_path));
+		channel_path_size = sizeof(chan_info->channel_path);
+		if (strlcpy(chan_info->channel_path, socket_path,
+			      channel_path_size) >= channel_path_size) {
+			RTE_LOG(ERR, CHANNEL_MANAGER, "Socket path is too long "
+				"'%s' >= %zu\n", socket_path, channel_path_size);
+			rte_free(chan_info);
+			chan_infos[i] = NULL;
+			goto error;
+		}
 
 		if (setup_host_channel_info(&chan_info, i) < 0) {
-- 
2.53.0

Re: [PATCH] examples/vm_power: fix format-truncation warning

[Stephen Hemminger]

On Wed, 25 Feb 2026 17:36:32 +0000
Kevin Traynor <ktraynor@redhat.com> wrote:

> Without libbsd-devel strlcpy is defined as rte_strlcpy and a warning is
> raised for format-truncation. Observed with gcc 15.2.1.
> 
> In function ‘rte_strlcpy’,
>     inlined from ‘add_host_channels’ at
> ../examples/vm_power_manager/channel_manager.c:600:3:
> ../lib/eal/include/rte_string_fns.h:63:24:
> warning: ‘%s’ directive output may be truncated writing up to
> 4095 bytes into a region of size 108 [-Wformat-truncation=]
> 63 |         return (size_t)snprintf(dst, size, "%s", src);
>    |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Check for truncation of socket_path[4096] into channel_path[108] to
> remove warning.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

Since socket_path is a unix domain socket path.
It should be UNIX_PATH_MAX (108) not PATH_MAX (4096)

Re: [PATCH] examples/vm_power: fix format-truncation warning

[Kevin Traynor]

On 25/02/2026 18:32, Stephen Hemminger wrote:
> On Wed, 25 Feb 2026 17:36:32 +0000
> Kevin Traynor <ktraynor@redhat.com> wrote:
> 
>> Without libbsd-devel strlcpy is defined as rte_strlcpy and a warning is
>> raised for format-truncation. Observed with gcc 15.2.1.
>>
>> In function ‘rte_strlcpy’,
>>     inlined from ‘add_host_channels’ at
>> ../examples/vm_power_manager/channel_manager.c:600:3:
>> ../lib/eal/include/rte_string_fns.h:63:24:
>> warning: ‘%s’ directive output may be truncated writing up to
>> 4095 bytes into a region of size 108 [-Wformat-truncation=]
>> 63 |         return (size_t)snprintf(dst, size, "%s", src);
>>    |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> Check for truncation of socket_path[4096] into channel_path[108] to
>> remove warning.
>>
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
> 
> Since socket_path is a unix domain socket path.
> It should be UNIX_PATH_MAX (108) not PATH_MAX (4096)
> 

Yeah, I had adjusted all the socket_path/names in the file to
UNIX_PATH_MAX as an initial fix but it spewed a different truncation
warning as one of them gets a copy from dirent->d_name which is 256.

So considering it's just an optimization of example code and hasn't
really been developed over the last few years, I just fixed the warning
that showed up.

Re: [PATCH] examples/vm_power: fix format-truncation warning

[Thomas Monjalon]

25/02/2026 18:36, Kevin Traynor:
> Without libbsd-devel strlcpy is defined as rte_strlcpy and a warning is
> raised for format-truncation. Observed with gcc 15.2.1.
> 
> In function ‘rte_strlcpy’,
>     inlined from ‘add_host_channels’ at
> ../examples/vm_power_manager/channel_manager.c:600:3:
> ../lib/eal/include/rte_string_fns.h:63:24:
> warning: ‘%s’ directive output may be truncated writing up to
> 4095 bytes into a region of size 108 [-Wformat-truncation=]
> 63 |         return (size_t)snprintf(dst, size, "%s", src);
>    |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Check for truncation of socket_path[4096] into channel_path[108] to
> remove warning.
> 
> Cc: stable@dpdk.org
> 
> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>

Applied, thanks.

Re: [PATCH] examples/vm_power: fix format-truncation warning

[Thomas Monjalon]

26/02/2026 11:48, Kevin Traynor:
> On 25/02/2026 18:32, Stephen Hemminger wrote:
> > On Wed, 25 Feb 2026 17:36:32 +0000
> > Kevin Traynor <ktraynor@redhat.com> wrote:
> > 
> >> Without libbsd-devel strlcpy is defined as rte_strlcpy and a warning is
> >> raised for format-truncation. Observed with gcc 15.2.1.
> >>
> >> In function ‘rte_strlcpy’,
> >>     inlined from ‘add_host_channels’ at
> >> ../examples/vm_power_manager/channel_manager.c:600:3:
> >> ../lib/eal/include/rte_string_fns.h:63:24:
> >> warning: ‘%s’ directive output may be truncated writing up to
> >> 4095 bytes into a region of size 108 [-Wformat-truncation=]
> >> 63 |         return (size_t)snprintf(dst, size, "%s", src);
> >>    |                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> >>
> >> Check for truncation of socket_path[4096] into channel_path[108] to
> >> remove warning.
> >>
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
> > 
> > Since socket_path is a unix domain socket path.
> > It should be UNIX_PATH_MAX (108) not PATH_MAX (4096)
> > 
> 
> Yeah, I had adjusted all the socket_path/names in the file to
> UNIX_PATH_MAX as an initial fix but it spewed a different truncation
> warning as one of them gets a copy from dirent->d_name which is 256.
> 
> So considering it's just an optimization of example code and hasn't
> really been developed over the last few years, I just fixed the warning
> that showed up.

Yes I suspect this example to have many other problems.
The whole example should be reconsidered.

Applied, thanks.