reftable/blocksource: adjust `read_block()` to return `ssize_t`

The `block_source_read_block()` function and its implementations return
an integer as a result that reflects either the number of bytes read, or
an error. As such its return type, a signed integer, isn't wrong, but it
doesn't give the reader a good hint what it actually returns.

Refactor the function to return an `ssize_t` instead, which is typical
for functions similar to read(3p) and should thus give readers a better
signal what they can expect as a result.

Adjust callers to better handle the returned value to avoid warnings
with -Wsign-compare. One of these callers is `reader_get_block()`, whose
return value is only ever used by its callers to figure out whether or
not the read was successful. So instead of bubbling up the `ssize_t`
there, too, we adapt it to only indicate success or errors.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/reftable/blocksource.c b/reftable/blocksource.c
index 52e0915a67..bba4a45b98 100644
--- a/reftable/blocksource.c
+++ b/reftable/blocksource.c
@@ -24,8 +24,8 @@ static void reftable_buf_close(void *b UNUSED)
 {
 }
 
-static int reftable_buf_read_block(void *v, struct reftable_block *dest,
-				   uint64_t off, uint32_t size)
+static ssize_t reftable_buf_read_block(void *v, struct reftable_block *dest,
+				       uint64_t off, uint32_t size)
 {
 	struct reftable_buf *b = v;
 	assert(off + size <= b->len);
@@ -78,8 +78,8 @@ static void file_close(void *v)
 	reftable_free(b);
 }
 
-static int file_read_block(void *v, struct reftable_block *dest, uint64_t off,
-			   uint32_t size)
+static ssize_t file_read_block(void *v, struct reftable_block *dest, uint64_t off,
+			       uint32_t size)
 {
 	struct file_block_source *b = v;
 	assert(off + size <= b->size);