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, 1 insertions, 1 deletions

diff --git a/src/test/test-install.c b/src/test/test-install.c
index a5328c9230..ab83a6aa0b 100644
--- a/src/test/test-install.c
+++ b/src/test/test-install.c
@@ -31,7 +31,7 @@ int main(int argc, char* argv[]) {
         const char *const files[] = { "avahi-daemon.service", NULL };
         const char *const files2[] = { "/home/lennart/test.service", NULL };
         UnitFileChange *changes = NULL;
-        unsigned n_changes = 0;
+        size_t n_changes = 0;
         UnitFileState state = 0;
 
         log_set_max_level(LOG_DEBUG);