[PATCH 09/10] reftable/blocksource: adjust `read_block()` to return `ssize_t`
- From
Patrick Steinhardt <ps@pks.im>
- Date
- Jan 16, 2025, 10:08 UTC
- Message-ID
- <20250116-b4-pks-reftable-sign-compare-v1-9-bd30e2ee96e7@pks.im>
- In-Reply-To
- <20250116-b4-pks-reftable-sign-compare-v1-0-bd30e2ee96e7@pks.im>
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> --- reftable/blocksource.c | 8 ++++---- reftable/reader.c | 30 +++++++++++++++++------------- reftable/reader.h | 6 +++--- reftable/reftable-blocksource.h | 11 +++++++---- 4 files changed, 31 insertions(+), 24 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); diff --git a/reftable/reader.c b/reftable/reader.c index 9df8a5ecb1..3f2e4b2800 100644 --- a/reftable/reader.c +++ b/reftable/reader.c @@ -20,11 +20,11 @@ uint64_t block_source_size(struct reftable_block_source *source) return source->ops->size(source->arg); } -int block_source_read_block(struct reftable_block_source *source, - struct reftable_block *dest, uint64_t off, - uint32_t size) +ssize_t block_source_read_block(struct reftable_block_source *source, + struct reftable_block *dest, uint64_t off, + uint32_t size) { - int result = source->ops->read_block(source->arg, dest, off, size); + ssize_t result = source->ops->read_block(source->arg, dest, off, size); dest->source = *source; return result; } @@ -57,14 +57,17 @@ static int reader_get_block(struct reftable_reader *r, struct reftable_block *dest, uint64_t off, uint32_t sz) { + ssize_t bytes_read; if (off >= r->size) return 0; - - if (off + sz > r->size) { + if (off + sz > r->size) sz = r->size - off; - } - return block_source_read_block(&r->source, dest, off, sz); + bytes_read = block_source_read_block(&r->source, dest, off, sz); + if (bytes_read < 0) + return (int)bytes_read; + + return 0; } enum reftable_hash reftable_reader_hash_id(struct reftable_reader *r) @@ -601,6 +604,7 @@ int reftable_reader_new(struct reftable_reader **out, struct reftable_reader *r; uint64_t file_size = block_source_size(source); uint32_t read_size; + ssize_t bytes_read; int err; REFTABLE_CALLOC_ARRAY(r, 1); @@ -619,8 +623,8 @@ int reftable_reader_new(struct reftable_reader **out, goto done; } - err = block_source_read_block(source, &header, 0, read_size); - if (err != read_size) { + bytes_read = block_source_read_block(source, &header, 0, read_size); + if (bytes_read < 0 || (size_t)bytes_read != read_size) { err = REFTABLE_IO_ERROR; goto done; } @@ -645,9 +649,9 @@ int reftable_reader_new(struct reftable_reader **out, r->hash_id = 0; r->refcount = 1; - err = block_source_read_block(source, &footer, r->size, - footer_size(r->version)); - if (err != footer_size(r->version)) { + bytes_read = block_source_read_block(source, &footer, r->size, + footer_size(r->version)); + if (bytes_read < 0 || (size_t)bytes_read != footer_size(r->version)) { err = REFTABLE_IO_ERROR; goto done; } diff --git a/reftable/reader.h b/reftable/reader.h index d2b48a4849..bb72108a6f 100644 --- a/reftable/reader.h +++ b/reftable/reader.h @@ -16,9 +16,9 @@ license that can be found in the LICENSE file or at uint64_t block_source_size(struct reftable_block_source *source); -int block_source_read_block(struct reftable_block_source *source, - struct reftable_block *dest, uint64_t off, - uint32_t size); +ssize_t block_source_read_block(struct reftable_block_source *source, + struct reftable_block *dest, uint64_t off, + uint32_t size); void block_source_close(struct reftable_block_source *source); /* metadata for a block type */ diff --git a/reftable/reftable-blocksource.h b/reftable/reftable-blocksource.h index f06ad52e0a..6b326aa5ea 100644 --- a/reftable/reftable-blocksource.h +++ b/reftable/reftable-blocksource.h @@ -31,10 +31,13 @@ struct reftable_block_source_vtable { /* returns the size of a block source */ uint64_t (*size)(void *source); - /* reads a segment from the block source. It is an error to read - beyond the end of the block */ - int (*read_block)(void *source, struct reftable_block *dest, - uint64_t off, uint32_t size); + /* + * Reads a segment from the block source. It is an error to read beyond + * the end of the block. + */ + ssize_t (*read_block)(void *source, struct reftable_block *dest, + uint64_t off, uint32_t size); + /* mark the block as read; may return the data back to malloc */ void (*return_block)(void *source, struct reftable_block *blockp);
-- 2.48.0.257.gd3603152ad.dirty