[PATCH 04/10] reftable/basics: adjust `common_prefix_size()` to return `size_t`

[Patrick Steinhardt <ps@xxxxxx>]

The `common_prefix_size()` function computes the length of the common
prefix between two buffers. As such its return value will always be an
unsigned integer, as the length cannot be negative. Regardless of that,
the function returns a signed integer, which is nonsensical and causes a
couple of -Wsign-compare warnings all over the place.

Adjust the function to return a `size_t` instead.

Signed-off-by: Patrick Steinhardt <ps@xxxxxx>
---
 reftable/basics.c                | 8 +++-----
 reftable/basics.h                | 2 +-
 reftable/record.c                | 4 ++--
 reftable/writer.c                | 5 ++---
 t/unit-tests/t-reftable-basics.c | 2 +-
 5 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/reftable/basics.c b/reftable/basics.c
index fe2b83ff83..10b234ea55 100644
--- a/reftable/basics.c
+++ b/reftable/basics.c
@@ -263,14 +263,12 @@ int names_equal(const char **a, const char **b)
 	return a[i] == b[i];
 }
 
-int common_prefix_size(struct reftable_buf *a, struct reftable_buf *b)
+size_t common_prefix_size(struct reftable_buf *a, struct reftable_buf *b)
 {
-	int p = 0;
-	for (; p < a->len && p < b->len; p++) {
+	size_t p = 0;
+	for (; p < a->len && p < b->len; p++)
 		if (a->buf[p] != b->buf[p])
 			break;
-	}
-
 	return p;
 }
 
diff --git a/reftable/basics.h b/reftable/basics.h
index 4bf71b0954..9ff81a68f8 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -169,7 +169,7 @@ static inline void *reftable_alloc_grow(void *p, size_t nelem, size_t elsize,
 #endif
 
 /* Find the longest shared prefix size of `a` and `b` */
-int common_prefix_size(struct reftable_buf *a, struct reftable_buf *b);
+size_t common_prefix_size(struct reftable_buf *a, struct reftable_buf *b);
 
 int hash_size(enum reftable_hash id);
 
diff --git a/reftable/record.c b/reftable/record.c
index 4e6541c307..69c09ec163 100644
--- a/reftable/record.c
+++ b/reftable/record.c
@@ -135,9 +135,9 @@ int reftable_encode_key(int *restart, struct string_view dest,
 			uint8_t extra)
 {
 	struct string_view start = dest;
-	int prefix_len = common_prefix_size(&prev_key, &key);
+	size_t prefix_len = common_prefix_size(&prev_key, &key);
 	uint64_t suffix_len = key.len - prefix_len;
-	int n = put_var_int(&dest, (uint64_t)prefix_len);
+	int n = put_var_int(&dest, prefix_len);
 	if (n < 0)
 		return -1;
 	string_view_consume(&dest, n);
diff --git a/reftable/writer.c b/reftable/writer.c
index 740c98038e..4e6ca2e368 100644
--- a/reftable/writer.c
+++ b/reftable/writer.c
@@ -585,10 +585,9 @@ static void update_common(void *void_arg, void *key)
 	struct common_prefix_arg *arg = void_arg;
 	struct obj_index_tree_node *entry = key;
 	if (arg->last) {
-		int n = common_prefix_size(&entry->hash, arg->last);
-		if (n > arg->max) {
+		size_t n = common_prefix_size(&entry->hash, arg->last);
+		if (n > arg->max)
 			arg->max = n;
-		}
 	}
 	arg->last = &entry->hash;
 }
diff --git a/t/unit-tests/t-reftable-basics.c b/t/unit-tests/t-reftable-basics.c
index 1d640b280f..9ba7eb05ad 100644
--- a/t/unit-tests/t-reftable-basics.c
+++ b/t/unit-tests/t-reftable-basics.c
@@ -120,7 +120,7 @@ int cmd_main(int argc UNUSED, const char *argv[] UNUSED)
 		for (size_t i = 0; i < ARRAY_SIZE(cases); i++) {
 			check(!reftable_buf_addstr(&a, cases[i].a));
 			check(!reftable_buf_addstr(&b, cases[i].b));
-			check_int(common_prefix_size(&a, &b), ==, cases[i].want);
+			check_uint(common_prefix_size(&a, &b), ==, cases[i].want);
 			reftable_buf_reset(&a);
 			reftable_buf_reset(&b);
 		}

-- 
2.48.0.257.gd3603152ad.dirty