Hi Michal,
On 31/5/24 09:28, Michal Privoznik wrote:
The unspoken premise of qemu_madvise() is that errno is set on
error. And it is mostly the case except for posix_madvise() which
is documented to return either zero (on success) or a positive
error number.
Watch out, Linux:
RETURN VALUE
On success, posix_madvise() returns 0. On failure,
it returns a positive error number.
but on Darwin:
RETURN VALUES
Upon successful completion, a value of 0 is returned.
Otherwise, a value of -1 is returned and errno is set
to indicate the error.
(Haven't checked other POSIX OSes).
So we likely need more #ifdef'ry here.
This means, we must set errno ourselves. And while
at it, make the function return a negative value on error, just
like other error paths do.
Signed-off-by: Michal Privoznik <mpriv...@redhat.com>
Reviewed-by: David Hildenbrand <da...@redhat.com>
---
util/osdep.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/util/osdep.c b/util/osdep.c
index e996c4744a..e42f4e8121 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -57,7 +57,12 @@ int qemu_madvise(void *addr, size_t len, int advice)
#if defined(CONFIG_MADVISE)
return madvise(addr, len, advice);
#elif defined(CONFIG_POSIX_MADVISE)
- return posix_madvise(addr, len, advice);
+ int rc = posix_madvise(addr, len, advice);
+ if (rc) {
+ errno = rc;
+ return -1;
+ }
+ return 0;
#else
errno = EINVAL;
return -1;
