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-rw-r--r--reftable/block.c437
-rw-r--r--reftable/block.h127
-rw-r--r--reftable/block_test.c120
3 files changed, 684 insertions, 0 deletions
diff --git a/reftable/block.c b/reftable/block.c
new file mode 100644
index 0000000000..855e3f5c94
--- /dev/null
+++ b/reftable/block.c
@@ -0,0 +1,437 @@
+/*
+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
+*/
+
+#include "block.h"
+
+#include "blocksource.h"
+#include "constants.h"
+#include "record.h"
+#include "reftable-error.h"
+#include "system.h"
+#include <zlib.h>
+
+int header_size(int version)
+{
+ switch (version) {
+ case 1:
+ return 24;
+ case 2:
+ return 28;
+ }
+ abort();
+}
+
+int footer_size(int version)
+{
+ switch (version) {
+ case 1:
+ return 68;
+ case 2:
+ return 72;
+ }
+ abort();
+}
+
+static int block_writer_register_restart(struct block_writer *w, int n,
+ int is_restart, struct strbuf *key)
+{
+ int rlen = w->restart_len;
+ if (rlen >= MAX_RESTARTS) {
+ is_restart = 0;
+ }
+
+ if (is_restart) {
+ rlen++;
+ }
+ if (2 + 3 * rlen + n > w->block_size - w->next)
+ return -1;
+ if (is_restart) {
+ if (w->restart_len == w->restart_cap) {
+ w->restart_cap = w->restart_cap * 2 + 1;
+ w->restarts = reftable_realloc(
+ w->restarts, sizeof(uint32_t) * w->restart_cap);
+ }
+
+ w->restarts[w->restart_len++] = w->next;
+ }
+
+ w->next += n;
+
+ strbuf_reset(&w->last_key);
+ strbuf_addbuf(&w->last_key, key);
+ w->entries++;
+ return 0;
+}
+
+void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf,
+ uint32_t block_size, uint32_t header_off, int hash_size)
+{
+ bw->buf = buf;
+ bw->hash_size = hash_size;
+ bw->block_size = block_size;
+ bw->header_off = header_off;
+ bw->buf[header_off] = typ;
+ bw->next = header_off + 4;
+ bw->restart_interval = 16;
+ bw->entries = 0;
+ bw->restart_len = 0;
+ bw->last_key.len = 0;
+}
+
+uint8_t block_writer_type(struct block_writer *bw)
+{
+ return bw->buf[bw->header_off];
+}
+
+/* adds the reftable_record to the block. Returns -1 if it does not fit, 0 on
+ success */
+int block_writer_add(struct block_writer *w, struct reftable_record *rec)
+{
+ struct strbuf empty = STRBUF_INIT;
+ struct strbuf last =
+ w->entries % w->restart_interval == 0 ? empty : w->last_key;
+ struct string_view out = {
+ .buf = w->buf + w->next,
+ .len = w->block_size - w->next,
+ };
+
+ struct string_view start = out;
+
+ int is_restart = 0;
+ struct strbuf key = STRBUF_INIT;
+ int n = 0;
+
+ reftable_record_key(rec, &key);
+ n = reftable_encode_key(&is_restart, out, last, key,
+ reftable_record_val_type(rec));
+ if (n < 0)
+ goto done;
+ string_view_consume(&out, n);
+
+ n = reftable_record_encode(rec, out, w->hash_size);
+ if (n < 0)
+ goto done;
+ string_view_consume(&out, n);
+
+ if (block_writer_register_restart(w, start.len - out.len, is_restart,
+ &key) < 0)
+ goto done;
+
+ strbuf_release(&key);
+ return 0;
+
+done:
+ strbuf_release(&key);
+ return -1;
+}
+
+int block_writer_finish(struct block_writer *w)
+{
+ int i;
+ for (i = 0; i < w->restart_len; i++) {
+ put_be24(w->buf + w->next, w->restarts[i]);
+ w->next += 3;
+ }
+
+ put_be16(w->buf + w->next, w->restart_len);
+ w->next += 2;
+ put_be24(w->buf + 1 + w->header_off, w->next);
+
+ if (block_writer_type(w) == BLOCK_TYPE_LOG) {
+ int block_header_skip = 4 + w->header_off;
+ uLongf src_len = w->next - block_header_skip;
+ uLongf dest_cap = src_len * 1.001 + 12;
+
+ uint8_t *compressed = reftable_malloc(dest_cap);
+ while (1) {
+ uLongf out_dest_len = dest_cap;
+ int zresult = compress2(compressed, &out_dest_len,
+ w->buf + block_header_skip,
+ src_len, 9);
+ if (zresult == Z_BUF_ERROR && dest_cap < LONG_MAX) {
+ dest_cap *= 2;
+ compressed =
+ reftable_realloc(compressed, dest_cap);
+ if (compressed)
+ continue;
+ }
+
+ if (Z_OK != zresult) {
+ reftable_free(compressed);
+ return REFTABLE_ZLIB_ERROR;
+ }
+
+ memcpy(w->buf + block_header_skip, compressed,
+ out_dest_len);
+ w->next = out_dest_len + block_header_skip;
+ reftable_free(compressed);
+ break;
+ }
+ }
+ return w->next;
+}
+
+uint8_t block_reader_type(struct block_reader *r)
+{
+ return r->block.data[r->header_off];
+}
+
+int block_reader_init(struct block_reader *br, struct reftable_block *block,
+ uint32_t header_off, uint32_t table_block_size,
+ int hash_size)
+{
+ uint32_t full_block_size = table_block_size;
+ uint8_t typ = block->data[header_off];
+ uint32_t sz = get_be24(block->data + header_off + 1);
+
+ uint16_t restart_count = 0;
+ uint32_t restart_start = 0;
+ uint8_t *restart_bytes = NULL;
+
+ if (!reftable_is_block_type(typ))
+ return REFTABLE_FORMAT_ERROR;
+
+ if (typ == BLOCK_TYPE_LOG) {
+ int block_header_skip = 4 + header_off;
+ uLongf dst_len = sz - block_header_skip; /* total size of dest
+ buffer. */
+ uLongf src_len = block->len - block_header_skip;
+ /* Log blocks specify the *uncompressed* size in their header.
+ */
+ uint8_t *uncompressed = reftable_malloc(sz);
+
+ /* Copy over the block header verbatim. It's not compressed. */
+ memcpy(uncompressed, block->data, block_header_skip);
+
+ /* Uncompress */
+ if (Z_OK !=
+ uncompress2(uncompressed + block_header_skip, &dst_len,
+ block->data + block_header_skip, &src_len)) {
+ reftable_free(uncompressed);
+ return REFTABLE_ZLIB_ERROR;
+ }
+
+ if (dst_len + block_header_skip != sz)
+ return REFTABLE_FORMAT_ERROR;
+
+ /* We're done with the input data. */
+ reftable_block_done(block);
+ block->data = uncompressed;
+ block->len = sz;
+ block->source = malloc_block_source();
+ full_block_size = src_len + block_header_skip;
+ } else if (full_block_size == 0) {
+ full_block_size = sz;
+ } else if (sz < full_block_size && sz < block->len &&
+ block->data[sz] != 0) {
+ /* If the block is smaller than the full block size, it is
+ padded (data followed by '\0') or the next block is
+ unaligned. */
+ full_block_size = sz;
+ }
+
+ restart_count = get_be16(block->data + sz - 2);
+ restart_start = sz - 2 - 3 * restart_count;
+ restart_bytes = block->data + restart_start;
+
+ /* transfer ownership. */
+ br->block = *block;
+ block->data = NULL;
+ block->len = 0;
+
+ br->hash_size = hash_size;
+ br->block_len = restart_start;
+ br->full_block_size = full_block_size;
+ br->header_off = header_off;
+ br->restart_count = restart_count;
+ br->restart_bytes = restart_bytes;
+
+ return 0;
+}
+
+static uint32_t block_reader_restart_offset(struct block_reader *br, int i)
+{
+ return get_be24(br->restart_bytes + 3 * i);
+}
+
+void block_reader_start(struct block_reader *br, struct block_iter *it)
+{
+ it->br = br;
+ strbuf_reset(&it->last_key);
+ it->next_off = br->header_off + 4;
+}
+
+struct restart_find_args {
+ int error;
+ struct strbuf key;
+ struct block_reader *r;
+};
+
+static int restart_key_less(size_t idx, void *args)
+{
+ struct restart_find_args *a = args;
+ uint32_t off = block_reader_restart_offset(a->r, idx);
+ struct string_view in = {
+ .buf = a->r->block.data + off,
+ .len = a->r->block_len - off,
+ };
+
+ /* the restart key is verbatim in the block, so this could avoid the
+ alloc for decoding the key */
+ struct strbuf rkey = STRBUF_INIT;
+ struct strbuf last_key = STRBUF_INIT;
+ uint8_t unused_extra;
+ int n = reftable_decode_key(&rkey, &unused_extra, last_key, in);
+ int result;
+ if (n < 0) {
+ a->error = 1;
+ return -1;
+ }
+
+ result = strbuf_cmp(&a->key, &rkey);
+ strbuf_release(&rkey);
+ return result;
+}
+
+void block_iter_copy_from(struct block_iter *dest, struct block_iter *src)
+{
+ dest->br = src->br;
+ dest->next_off = src->next_off;
+ strbuf_reset(&dest->last_key);
+ strbuf_addbuf(&dest->last_key, &src->last_key);
+}
+
+int block_iter_next(struct block_iter *it, struct reftable_record *rec)
+{
+ struct string_view in = {
+ .buf = it->br->block.data + it->next_off,
+ .len = it->br->block_len - it->next_off,
+ };
+ struct string_view start = in;
+ struct strbuf key = STRBUF_INIT;
+ uint8_t extra = 0;
+ int n = 0;
+
+ if (it->next_off >= it->br->block_len)
+ return 1;
+
+ n = reftable_decode_key(&key, &extra, it->last_key, in);
+ if (n < 0)
+ return -1;
+
+ string_view_consume(&in, n);
+ n = reftable_record_decode(rec, key, extra, in, it->br->hash_size);
+ if (n < 0)
+ return -1;
+ string_view_consume(&in, n);
+
+ strbuf_reset(&it->last_key);
+ strbuf_addbuf(&it->last_key, &key);
+ it->next_off += start.len - in.len;
+ strbuf_release(&key);
+ return 0;
+}
+
+int block_reader_first_key(struct block_reader *br, struct strbuf *key)
+{
+ struct strbuf empty = STRBUF_INIT;
+ int off = br->header_off + 4;
+ struct string_view in = {
+ .buf = br->block.data + off,
+ .len = br->block_len - off,
+ };
+
+ uint8_t extra = 0;
+ int n = reftable_decode_key(key, &extra, empty, in);
+ if (n < 0)
+ return n;
+
+ return 0;
+}
+
+int block_iter_seek(struct block_iter *it, struct strbuf *want)
+{
+ return block_reader_seek(it->br, it, want);
+}
+
+void block_iter_close(struct block_iter *it)
+{
+ strbuf_release(&it->last_key);
+}
+
+int block_reader_seek(struct block_reader *br, struct block_iter *it,
+ struct strbuf *want)
+{
+ struct restart_find_args args = {
+ .key = *want,
+ .r = br,
+ };
+ struct reftable_record rec = reftable_new_record(block_reader_type(br));
+ struct strbuf key = STRBUF_INIT;
+ int err = 0;
+ struct block_iter next = {
+ .last_key = STRBUF_INIT,
+ };
+
+ int i = binsearch(br->restart_count, &restart_key_less, &args);
+ if (args.error) {
+ err = REFTABLE_FORMAT_ERROR;
+ goto done;
+ }
+
+ it->br = br;
+ if (i > 0) {
+ i--;
+ it->next_off = block_reader_restart_offset(br, i);
+ } else {
+ it->next_off = br->header_off + 4;
+ }
+
+ /* We're looking for the last entry less/equal than the wanted key, so
+ we have to go one entry too far and then back up.
+ */
+ while (1) {
+ block_iter_copy_from(&next, it);
+ err = block_iter_next(&next, &rec);
+ if (err < 0)
+ goto done;
+
+ reftable_record_key(&rec, &key);
+ if (err > 0 || strbuf_cmp(&key, want) >= 0) {
+ err = 0;
+ goto done;
+ }
+
+ block_iter_copy_from(it, &next);
+ }
+
+done:
+ strbuf_release(&key);
+ strbuf_release(&next.last_key);
+ reftable_record_destroy(&rec);
+
+ return err;
+}
+
+void block_writer_release(struct block_writer *bw)
+{
+ FREE_AND_NULL(bw->restarts);
+ strbuf_release(&bw->last_key);
+ /* the block is not owned. */
+}
+
+void reftable_block_done(struct reftable_block *blockp)
+{
+ struct reftable_block_source source = blockp->source;
+ if (blockp && source.ops)
+ source.ops->return_block(source.arg, blockp);
+ blockp->data = NULL;
+ blockp->len = 0;
+ blockp->source.ops = NULL;
+ blockp->source.arg = NULL;
+}
diff --git a/reftable/block.h b/reftable/block.h
new file mode 100644
index 0000000000..e207706a64
--- /dev/null
+++ b/reftable/block.h
@@ -0,0 +1,127 @@
+/*
+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 BLOCK_H
+#define BLOCK_H
+
+#include "basics.h"
+#include "record.h"
+#include "reftable-blocksource.h"
+
+/*
+ * Writes reftable blocks. The block_writer is reused across blocks to minimize
+ * allocation overhead.
+ */
+struct block_writer {
+ uint8_t *buf;
+ uint32_t block_size;
+
+ /* Offset ofof the global header. Nonzero in the first block only. */
+ uint32_t header_off;
+
+ /* How often to restart keys. */
+ int restart_interval;
+ int hash_size;
+
+ /* Offset of next uint8_t to write. */
+ uint32_t next;
+ uint32_t *restarts;
+ uint32_t restart_len;
+ uint32_t restart_cap;
+
+ struct strbuf last_key;
+ int entries;
+};
+
+/*
+ * initializes the blockwriter to write `typ` entries, using `buf` as temporary
+ * storage. `buf` is not owned by the block_writer. */
+void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf,
+ uint32_t block_size, uint32_t header_off, int hash_size);
+
+/* returns the block type (eg. 'r' for ref records. */
+uint8_t block_writer_type(struct block_writer *bw);
+
+/* appends the record, or -1 if it doesn't fit. */
+int block_writer_add(struct block_writer *w, struct reftable_record *rec);
+
+/* appends the key restarts, and compress the block if necessary. */
+int block_writer_finish(struct block_writer *w);
+
+/* clears out internally allocated block_writer members. */
+void block_writer_release(struct block_writer *bw);
+
+/* Read a block. */
+struct block_reader {
+ /* offset of the block header; nonzero for the first block in a
+ * reftable. */
+ uint32_t header_off;
+
+ /* the memory block */
+ struct reftable_block block;
+ int hash_size;
+
+ /* size of the data, excluding restart data. */
+ uint32_t block_len;
+ uint8_t *restart_bytes;
+ uint16_t restart_count;
+
+ /* size of the data in the file. For log blocks, this is the compressed
+ * size. */
+ uint32_t full_block_size;
+};
+
+/* Iterate over entries in a block */
+struct block_iter {
+ /* offset within the block of the next entry to read. */
+ uint32_t next_off;
+ struct block_reader *br;
+
+ /* key for last entry we read. */
+ struct strbuf last_key;
+};
+
+/* initializes a block reader. */
+int block_reader_init(struct block_reader *br, struct reftable_block *bl,
+ uint32_t header_off, uint32_t table_block_size,
+ int hash_size);
+
+/* Position `it` at start of the block */
+void block_reader_start(struct block_reader *br, struct block_iter *it);
+
+/* Position `it` to the `want` key in the block */
+int block_reader_seek(struct block_reader *br, struct block_iter *it,
+ struct strbuf *want);
+
+/* Returns the block type (eg. 'r' for refs) */
+uint8_t block_reader_type(struct block_reader *r);
+
+/* Decodes the first key in the block */
+int block_reader_first_key(struct block_reader *br, struct strbuf *key);
+
+void block_iter_copy_from(struct block_iter *dest, struct block_iter *src);
+
+/* return < 0 for error, 0 for OK, > 0 for EOF. */
+int block_iter_next(struct block_iter *it, struct reftable_record *rec);
+
+/* Seek to `want` with in the block pointed to by `it` */
+int block_iter_seek(struct block_iter *it, struct strbuf *want);
+
+/* deallocate memory for `it`. The block reader and its block is left intact. */
+void block_iter_close(struct block_iter *it);
+
+/* size of file header, depending on format version */
+int header_size(int version);
+
+/* size of file footer, depending on format version */
+int footer_size(int version);
+
+/* returns a block to its source. */
+void reftable_block_done(struct reftable_block *ret);
+
+#endif
diff --git a/reftable/block_test.c b/reftable/block_test.c
new file mode 100644
index 0000000000..4b3ea262dc
--- /dev/null
+++ b/reftable/block_test.c
@@ -0,0 +1,120 @@
+/*
+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
+*/
+
+#include "block.h"
+
+#include "system.h"
+#include "blocksource.h"
+#include "basics.h"
+#include "constants.h"
+#include "record.h"
+#include "test_framework.h"
+#include "reftable-tests.h"
+
+static void test_block_read_write(void)
+{
+ const int header_off = 21; /* random */
+ char *names[30];
+ const int N = ARRAY_SIZE(names);
+ const int block_size = 1024;
+ struct reftable_block block = { NULL };
+ struct block_writer bw = {
+ .last_key = STRBUF_INIT,
+ };
+ struct reftable_ref_record ref = { NULL };
+ struct reftable_record rec = { NULL };
+ int i = 0;
+ int n;
+ struct block_reader br = { 0 };
+ struct block_iter it = { .last_key = STRBUF_INIT };
+ int j = 0;
+ struct strbuf want = STRBUF_INIT;
+
+ block.data = reftable_calloc(block_size);
+ block.len = block_size;
+ block.source = malloc_block_source();
+ block_writer_init(&bw, BLOCK_TYPE_REF, block.data, block_size,
+ header_off, hash_size(GIT_SHA1_FORMAT_ID));
+ reftable_record_from_ref(&rec, &ref);
+
+ for (i = 0; i < N; i++) {
+ char name[100];
+ uint8_t hash[GIT_SHA1_RAWSZ];
+ snprintf(name, sizeof(name), "branch%02d", i);
+ memset(hash, i, sizeof(hash));
+
+ ref.refname = name;
+ ref.value_type = REFTABLE_REF_VAL1;
+ ref.value.val1 = hash;
+
+ names[i] = xstrdup(name);
+ n = block_writer_add(&bw, &rec);
+ ref.refname = NULL;
+ ref.value_type = REFTABLE_REF_DELETION;
+ EXPECT(n == 0);
+ }
+
+ n = block_writer_finish(&bw);
+ EXPECT(n > 0);
+
+ block_writer_release(&bw);
+
+ block_reader_init(&br, &block, header_off, block_size, GIT_SHA1_RAWSZ);
+
+ block_reader_start(&br, &it);
+
+ while (1) {
+ int r = block_iter_next(&it, &rec);
+ EXPECT(r >= 0);
+ if (r > 0) {
+ break;
+ }
+ EXPECT_STREQ(names[j], ref.refname);
+ j++;
+ }
+
+ reftable_record_release(&rec);
+ block_iter_close(&it);
+
+ for (i = 0; i < N; i++) {
+ struct block_iter it = { .last_key = STRBUF_INIT };
+ strbuf_reset(&want);
+ strbuf_addstr(&want, names[i]);
+
+ n = block_reader_seek(&br, &it, &want);
+ EXPECT(n == 0);
+
+ n = block_iter_next(&it, &rec);
+ EXPECT(n == 0);
+
+ EXPECT_STREQ(names[i], ref.refname);
+
+ want.len--;
+ n = block_reader_seek(&br, &it, &want);
+ EXPECT(n == 0);
+
+ n = block_iter_next(&it, &rec);
+ EXPECT(n == 0);
+ EXPECT_STREQ(names[10 * (i / 10)], ref.refname);
+
+ block_iter_close(&it);
+ }
+
+ reftable_record_release(&rec);
+ reftable_block_done(&br.block);
+ strbuf_release(&want);
+ for (i = 0; i < N; i++) {
+ reftable_free(names[i]);
+ }
+}
+
+int block_test_main(int argc, const char *argv[])
+{
+ RUN_TEST(test_block_read_write);
+ return 0;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-12 17:25:00 +0000