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, 3 insertions, 4 deletions

diff --git a/src/resolve/resolved-mdns.c b/src/resolve/resolved-mdns.c
index aa6daf2971..e27b0f4b70 100644
--- a/src/resolve/resolved-mdns.c
+++ b/src/resolve/resolved-mdns.c
@@ -133,7 +133,7 @@ static int mdns_packet_extract_matching_rrs(DnsPacket *p, DnsResourceKey *key, D
         assert(ret_rrs);
         assert_return(DNS_PACKET_NSCOUNT(p) > 0, -EINVAL);
 
-        for (unsigned i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
+        for (size_t i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
                 r = dns_resource_key_match_rr(key, p->answer->items[i].rr, NULL);
                 if (r < 0)
                         return r;
@@ -148,7 +148,7 @@ static int mdns_packet_extract_matching_rrs(DnsPacket *p, DnsResourceKey *key, D
         if (!list)
                 return -ENOMEM;
 
-        for (unsigned i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
+        for (size_t i = DNS_PACKET_ANCOUNT(p); i < (DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)); i++) {
                 r = dns_resource_key_match_rr(key, p->answer->items[i].rr, NULL);
                 if (r < 0)
                         return r;
@@ -166,8 +166,7 @@ static int mdns_packet_extract_matching_rrs(DnsPacket *p, DnsResourceKey *key, D
 static int mdns_do_tiebreak(DnsResourceKey *key, DnsAnswer *answer, DnsPacket *p) {
         _cleanup_free_ DnsResourceRecord **our = NULL, **remote = NULL;
         DnsResourceRecord *rr;
-        unsigned i = 0;
-        unsigned size;
+        size_t i = 0, size;
         int r;
 
         size = dns_answer_size(answer);