reftable/block: create public interface for reading blocks
While users of the reftable library wouldn't generally require access to individual blocks in a reftable table, there are valid usecases where one may require low-level access to them. One such upcoming usecase in the Git codebase is to implement consistency checks for the reftable library where we want to verify each block individually. Create a public interface for reading blocks. The interface isn't yet complete and lacks e.g. a way to read individual records from a block. Such missing functionality will be backfilled in subsequent commits. Note that this change also requires us to expose `reftable_buf`, which is used by the `reftable_block_first_key()` function. Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Patrick Steinhardt committed
Apr 7, 2025 at 15:16 UTC
655e18d6b4f845090b0ba4761105b32726893ecb
4 files changed
+78
-54
reftable/basics.h
-7
index 96a2f0d382..d8888c1262 100644
--- a/reftable/basics.h
+++ b/reftable/basics.h
@@ -18,13 +18,6 @@
#define REFTABLE_UNUSED __attribute__((__unused__))
-struct reftable_buf {
- size_t alloc;
- size_t len;
- char *buf;
-};
-#define REFTABLE_BUF_INIT { 0 }
-
/*
* Initialize the buffer such that it is ready for use. This is equivalent to
* using REFTABLE_BUF_INIT for stack-allocated variables.
reftable/block.h
+1
-47
index 422e2f872c..4f7f29028c 100644
--- a/reftable/block.h
+++ b/reftable/block.h
@@ -11,6 +11,7 @@
#include "basics.h"
#include "record.h"
+#include "reftable-block.h"
#include "reftable-blocksource.h"
/*
@@ -62,53 +63,6 @@ int block_writer_finish(struct block_writer *w);
/* clears out internally allocated block_writer members. */
void block_writer_release(struct block_writer *bw);
-/*
- * A block part of a reftable. Contains records as well as some metadata
- * describing them.
- */
-struct reftable_block {
- /* offset of the block header; nonzero for the first block in a
- * reftable. */
- uint32_t header_off;
-
- /* the memory block */
- struct reftable_block_data block_data;
- uint32_t hash_size;
-
- /* Uncompressed data for log entries. */
- struct z_stream_s *zstream;
- unsigned char *uncompressed_data;
- size_t uncompressed_cap;
-
- /*
- * Restart point data. Restart points are located after the block's
- * record data.
- */
- uint16_t restart_count;
- uint32_t restart_off;
-
- /* size of the data in the file. For log blocks, this is the compressed
- * size. */
- uint32_t full_block_size;
- uint8_t block_type;
-};
-
-/*
- * Initialize a reftable block from the given block source.
- */
-int reftable_block_init(struct reftable_block *b,
- struct reftable_block_source *source,
- uint32_t offset, uint32_t header_size,
- uint32_t table_block_size, uint32_t hash_size);
-
-void reftable_block_release(struct reftable_block *b);
-
-/* Returns the block type (eg. 'r' for refs) */
-uint8_t reftable_block_type(const struct reftable_block *b);
-
-/* Decodes the first key in the block */
-int reftable_block_first_key(const struct reftable_block *b, struct reftable_buf *key);
-
/* Iterate over entries in a block */
struct block_iter {
/* offset within the block of the next entry to read. */
reftable/reftable-basics.h
+8
index ed7c7c9ac2..6d73f19c85 100644
--- a/reftable/reftable-basics.h
+++ b/reftable/reftable-basics.h
@@ -11,6 +11,14 @@
#include <stddef.h>
+/* A buffer that contains arbitrary byte slices. */
+struct reftable_buf {
+ size_t alloc;
+ size_t len;
+ char *buf;
+};
+#define REFTABLE_BUF_INIT { 0 }
+
/*
* Hash functions understood by the reftable library. Note that the values are
* arbitrary and somewhat random such that we can easily detect cases where the
reftable/reftable-block.h
+69
new file mode 100644
index 0000000000..13bd68be8c
--- /dev/null
+++ b/reftable/reftable-block.h
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file or at
+ * https://developers.google.com/open-source/licenses/bsd
+ */
+
+#ifndef REFTABLE_BLOCK_H
+#define REFTABLE_BLOCK_H
+
+#include <stdint.h>
+
+#include "reftable-basics.h"
+#include "reftable-blocksource.h"
+
+struct z_stream_s;
+
+/*
+ * A block part of a reftable. Contains records as well as some metadata
+ * describing them.
+ */
+struct reftable_block {
+ /*
+ * Offset of the block header; nonzero for the first block in a
+ * reftable.
+ */
+ uint32_t header_off;
+
+ /* The memory block. */
+ struct reftable_block_data block_data;
+ uint32_t hash_size;
+
+ /* Uncompressed data for log entries. */
+ struct z_stream_s *zstream;
+ unsigned char *uncompressed_data;
+ size_t uncompressed_cap;
+
+ /*
+ * Restart point data. Restart points are located after the block's
+ * record data.
+ */
+ uint16_t restart_count;
+ uint32_t restart_off;
+
+ /*
+ * Size of the data in the file. For log blocks, this is the compressed
+ * size.
+ */
+ uint32_t full_block_size;
+ uint8_t block_type;
+};
+
+/* Initialize a reftable block from the given block source. */
+int reftable_block_init(struct reftable_block *b,
+ struct reftable_block_source *source,
+ uint32_t offset, uint32_t header_size,
+ uint32_t table_block_size, uint32_t hash_size);
+
+/* Release resources allocated by the block. */
+void reftable_block_release(struct reftable_block *b);
+
+/* Returns the block type (eg. 'r' for refs). */
+uint8_t reftable_block_type(const struct reftable_block *b);
+
+/* Decodes the first key in the block. */
+int reftable_block_first_key(const struct reftable_block *b, struct reftable_buf *key);
+
+#endif /* REFTABLE_BLOCK_H */