basic/xattr-util: do not cast ssize_t to int

gcc warns about unitialized memory access because it notices that ssize_t which
is < 0 could be cast to positive int value. We know that this can't really
happen because only -1 can be returned, but OTOH, in principle a large
*positive* value cannot be cast properly. This is unlikely too, since xattrs
cannot be too large, but it seems cleaner to just use a size_t to return the
value and avoid the cast altoghter. This makes the code simpler and gcc is
happy too.

The following warning goes away:
[113/1502] Compiling C object 'src/basic/basic@sta/xattr-util.c.o'.
In file included from ../src/basic/alloc-util.h:28:0,
                 from ../src/basic/xattr-util.c:30:
../src/basic/xattr-util.c: In function ‘fd_getcrtime_at’:
../src/basic/macro.h:207:60: warning: ‘b’ may be used uninitialized in this function [-Wmaybe-uninitialized]
                 UNIQ_T(A,aq) < UNIQ_T(B,bq) ? UNIQ_T(A,aq) : UNIQ_T(B,bq); \
                                                            ^
../src/basic/xattr-util.c:155:19: note: ‘b’ was declared here
         usec_t a, b;
                   ^

1 files changed, 7 insertions, 1 deletions

diff --git a/src/basic/xattr-util.h b/src/basic/xattr-util.h
index 63ac72f72..e593c210f 100644
--- a/src/basic/xattr-util.h
+++ b/src/basic/xattr-util.h
@@ -30,7 +30,13 @@ int getxattr_malloc(const char *path, const char *name, char **value, bool allow
 int fgetxattr_malloc(int fd, const char *name, char **value);
 
 #if 0 /// UNNEEDED by elogind
-ssize_t fgetxattrat_fake(int dirfd, const char *filename, const char *attribute, void *value, size_t size, int flags);
+int fgetxattrat_fake(
+                int dirfd,
+                const char *filename,
+                const char *attribute,
+                void *value, size_t size,
+                int flags,
+                size_t *ret_size);
 
 int fd_setcrtime(int fd, usec_t usec);