reftable/block: adapt header and footer size to return a size_t

The functions `header_size()` and `footer_size()` return a positive
integer representing the size of the header and footer, respectively,
dependent on the version of the reftable format. Similar to the
preceding commit, these functions return a signed integer though, which
is nonsensical given that there is no way for these functions to return
negative.

Adapt the functions to return a `size_t` instead to fix a couple of sign
comparison warnings.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

reftable/block.c

@@ -15,7 +15,7 @@ license that can be found in the LICENSE file or at
 #include "system.h"
 #include <zlib.h>
 
-int header_size(int version)
+size_t header_size(int version)
 {
 	switch (version) {
 	case 1:
@@ -26,7 +26,7 @@ int header_size(int version)
 	abort();
 }
 
-int footer_size(int version)
+size_t footer_size(int version)
 {
 	switch (version) {
 	case 1:

reftable/block.h

@@ -137,10 +137,10 @@ void block_iter_reset(struct block_iter *it);
 void block_iter_close(struct block_iter *it);
 
 /* size of file header, depending on format version */
-int header_size(int version);
+size_t header_size(int version);
 
 /* size of file footer, depending on format version */
-int footer_size(int version);
+size_t footer_size(int version);
 
 /* returns a block to its source. */
 void reftable_block_done(struct reftable_block *ret);

t/unit-tests/t-reftable-readwrite.c

@@ -643,7 +643,7 @@ static void t_write_empty_table(void)
 	check_int(err, ==, REFTABLE_EMPTY_TABLE_ERROR);
 	reftable_writer_free(w);
 
-	check_int(buf.len, ==, header_size(1) + footer_size(1));
+	check_uint(buf.len, ==, header_size(1) + footer_size(1));
 
 	block_source_from_buf(&source, &buf);