hi Zorro
在 2021/1/30 12:58, Zorro Lang 写道:
On Thu, Jan 28, 2021 at 02:50:10PM +0800, Sun Ke wrote:
when run make, show:
swapon.c:135:3: warning: 'p' may be used uninitialized in this function
[-Wmaybe-uninitialized]
memcpy(p, buf, BUF_SIZE);
^~~~~~~~~~~~~~~~~~~~~~~~
fix it.
If you don't have a situation to prove this's a real bug, I guess the gcc might
think the 'p' can be used uninitialized at here when verb is TEST_MWRITE_BEFORE_AND_MWRITE_AFTER:
case TEST_MWRITE_BEFORE_AND_MWRITE_AFTER:
memcpy(p, buf, BUF_SIZE);
break;
But from the code logic, if verb is TEST_MWRITE_BEFORE_AND_MWRITE_AFTER, the 'p'
will be initialized by:
switch (verb) {
case TEST_MWRITE_BEFORE_AND_MWRITE_AFTER:
case TEST_MWRITE_BEFORE:
p = mmap(NULL, BUF_SIZE, PROT_WRITE | PROT_READ, MAP_SHARED,
So I think this's a fake uninitialized warning (Maybe I'm wrong. But if I'm right,
better to specify that in commit log).
Yes, you are right.
Sorry, I did not analyse the code logic carefully.
Anyway, I personally don't object to initialize a pointer to NULL at beginning,
and make a build warning disappear. Leave the decision to maintainer :)
I will improve the commit.
Thanks,
Zorro
Thanks,
Sun Ke
Signed-off-by: Sun Ke <sunke32@xxxxxxxxxx>
---
src/swapon.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/swapon.c b/src/swapon.c
index afaed405..fe8949a3 100644
--- a/src/swapon.c
+++ b/src/swapon.c
@@ -41,7 +41,7 @@ int main(int argc, char **argv)
.sa_handler = handle_signal,
};
enum verbs verb = TEST_SWAPON;
- void *p;
+ void *p = NULL;
ssize_t sz;
int fd = -1;
int ret, c;
--
2.13.6
.
