tree-wide: be more careful with the type of array sizes

Previously we were a bit sloppy with the index and size types of arrays,
we'd regularly use unsigned. While I don't think this ever resulted in
real issues I think we should be more careful there and follow a
stricter regime: unless there's a strong reason not to use size_t for
array sizes and indexes, size_t it should be. Any allocations we do
ultimately will use size_t anyway, and converting forth and back between
unsigned and size_t will always be a source of problems.

Note that on 32bit machines "unsigned" and "size_t" are equivalent, and
on 64bit machines our arrays shouldn't grow that large anyway, and if
they do we have a problem, however that kind of overly large allocation
we have protections for usually, but for overflows we do not have that
so much, hence let's add it.

So yeah, it's a story of the current code being already "good enough",
but I think some extra type hygiene is better.

This patch tries to be comprehensive, but it probably isn't and I missed
a few cases. But I guess we can cover that later as we notice it. Among
smaller fixes, this changes:

1. strv_length()' return type becomes size_t

2. the unit file changes array size becomes size_t

3. DNS answer and query array sizes become size_t

Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=76745

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libsystemd/sd-login/sd-login.c b/src/libsystemd/sd-login/sd-login.c
index 855f040c74..3f73dadc2e 100644
--- a/src/libsystemd/sd-login/sd-login.c
+++ b/src/libsystemd/sd-login/sd-login.c
@@ -402,7 +402,7 @@ static int uid_get_array(uid_t uid, const char *variable, char ***array) {
                 return -ENOMEM;
 
         strv_uniq(a);
-        r = strv_length(a);
+        r = (int) strv_length(a);
 
         if (array)
                 *array = a;
@@ -726,7 +726,7 @@ _public_ int sd_seat_get_sessions(const char *seat, char ***sessions, uid_t **ui
                 }
         }
 
-        r = strv_length(a);
+        r = (int) strv_length(a);
 
         if (sessions)
                 *sessions = TAKE_PTR(a);