The ftruncate() function is declared with the warn_unused_result
attribute, which generates a warning when compiling libv4lconvert:
[60/340] Compiling C object lib/libv4lconvert/libv4lconvert.so.0.0.0.p/control_libv4lcontrol.c.o
../lib/libv4lconvert/control/libv4lcontrol.c: In function ‘v4lcontrol_create’:
../lib/libv4lconvert/control/libv4lcontrol.c:728:17: warning: ignoring return value of ‘ftruncate’ declared with attribute ‘warn_unused_result’ [-Wunused-result]
728 | ftruncate(shm_fd, V4LCONTROL_SHM_SIZE);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fix it by checking the return value and falling back to malloc-ed memory
for controls, as done when mmap() fails.
While at it, fix a typo in a comment, and drop an unneeded "error" word
from an error message.
Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
---
lib/libv4lconvert/control/libv4lcontrol.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)
diff --git a/lib/libv4lconvert/control/libv4lcontrol.c b/lib/libv4lconvert/control/libv4lcontrol.c
index 7296de1d0fcb..676719372bb7 100644
--- a/lib/libv4lconvert/control/libv4lcontrol.c
+++ b/lib/libv4lconvert/control/libv4lcontrol.c
@@ -725,16 +725,21 @@ struct v4lcontrol_data *v4lcontrol_create(int fd, void *dev_ops_priv,
if (shm_fd >= 0) {
/* Set the shared memory size */
- ftruncate(shm_fd, V4LCONTROL_SHM_SIZE);
+ int ret = ftruncate(shm_fd, V4LCONTROL_SHM_SIZE);
+ if (ret) {
+ perror("libv4lcontrol: shm ftruncate failed");
+ close(shm_fd);
+ } else {
+ /* Retrieve a pointer to the shm object */
+ data->shm_values = mmap(NULL, V4LCONTROL_SHM_SIZE,
+ PROT_READ | PROT_WRITE,
+ MAP_SHARED, shm_fd, 0);
+ close(shm_fd);
- /* Retreive a pointer to the shm object */
- data->shm_values = mmap(NULL, V4LCONTROL_SHM_SIZE, (PROT_READ | PROT_WRITE),
- MAP_SHARED, shm_fd, 0);
- close(shm_fd);
-
- if (data->shm_values == MAP_FAILED) {
- perror("libv4lcontrol: error shm mmap failed");
- data->shm_values = NULL;
+ if (data->shm_values == MAP_FAILED) {
+ perror("libv4lcontrol: shm mmap failed");
+ data->shm_values = NULL;
+ }
}
} else
perror("libv4lcontrol: error creating shm segment failed");
--
Regards,
Laurent Pinchart
