From: Han-Wen Nienhuys <hanwen@xxxxxxxxxx> This supports reading a single reftable file. The commit introduces an abstract iterator type, which captures the usecases both of reading individual refs, and iterating over a segment of the ref namespace. Signed-off-by: Han-Wen Nienhuys <hanwen@xxxxxxxxxx> --- Makefile | 3 + reftable/iter.c | 242 ++++++++++++ reftable/iter.h | 75 ++++ reftable/reader.c | 733 +++++++++++++++++++++++++++++++++++ reftable/reader.h | 75 ++++ reftable/reftable-iterator.h | 37 ++ reftable/reftable-reader.h | 89 +++++ 7 files changed, 1254 insertions(+) create mode 100644 reftable/iter.c create mode 100644 reftable/iter.h create mode 100644 reftable/reader.c create mode 100644 reftable/reader.h create mode 100644 reftable/reftable-iterator.h create mode 100644 reftable/reftable-reader.h diff --git a/Makefile b/Makefile index 3e33a409f0..51dbcb1b9c 100644 --- a/Makefile +++ b/Makefile @@ -2393,8 +2393,11 @@ REFTABLE_OBJS += reftable/basics.o REFTABLE_OBJS += reftable/error.o REFTABLE_OBJS += reftable/block.o REFTABLE_OBJS += reftable/blocksource.o +REFTABLE_OBJS += reftable/iter.o REFTABLE_OBJS += reftable/publicbasics.o +REFTABLE_OBJS += reftable/reader.o REFTABLE_OBJS += reftable/record.o +REFTABLE_OBJS += reftable/reftable.o REFTABLE_OBJS += reftable/tree.o REFTABLE_OBJS += reftable/writer.o REFTABLE_OBJS += reftable/zlib-compat.o diff --git a/reftable/iter.c b/reftable/iter.c new file mode 100644 index 0000000000..63d87b758c --- /dev/null +++ b/reftable/iter.c @@ -0,0 +1,242 @@ +/* +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 "iter.h" + +#include "system.h" + +#include "block.h" +#include "constants.h" +#include "reader.h" +#include "reftable-error.h" + +int iterator_is_null(struct reftable_iterator *it) +{ + return it->ops == NULL; +} + +static int empty_iterator_next(void *arg, struct reftable_record *rec) +{ + return 1; +} + +static void empty_iterator_close(void *arg) +{ +} + +static struct reftable_iterator_vtable empty_vtable = { + .next = &empty_iterator_next, + .close = &empty_iterator_close, +}; + +void iterator_set_empty(struct reftable_iterator *it) +{ + assert(it->ops == NULL); + it->iter_arg = NULL; + it->ops = &empty_vtable; +} + +int iterator_next(struct reftable_iterator *it, struct reftable_record *rec) +{ + return it->ops->next(it->iter_arg, rec); +} + +void reftable_iterator_destroy(struct reftable_iterator *it) +{ + if (it->ops == NULL) { + return; + } + it->ops->close(it->iter_arg); + it->ops = NULL; + FREE_AND_NULL(it->iter_arg); +} + +int reftable_iterator_next_ref(struct reftable_iterator *it, + struct reftable_ref_record *ref) +{ + struct reftable_record rec = { NULL }; + reftable_record_from_ref(&rec, ref); + return iterator_next(it, &rec); +} + +int reftable_iterator_next_log(struct reftable_iterator *it, + struct reftable_log_record *log) +{ + struct reftable_record rec = { NULL }; + reftable_record_from_log(&rec, log); + return iterator_next(it, &rec); +} + +static void filtering_ref_iterator_close(void *iter_arg) +{ + struct filtering_ref_iterator *fri = + (struct filtering_ref_iterator *)iter_arg; + strbuf_release(&fri->oid); + reftable_iterator_destroy(&fri->it); +} + +static int filtering_ref_iterator_next(void *iter_arg, + struct reftable_record *rec) +{ + struct filtering_ref_iterator *fri = + (struct filtering_ref_iterator *)iter_arg; + struct reftable_ref_record *ref = + (struct reftable_ref_record *)rec->data; + int err = 0; + while (1) { + err = reftable_iterator_next_ref(&fri->it, ref); + if (err != 0) { + break; + } + + if (fri->double_check) { + struct reftable_iterator it = { NULL }; + + err = reftable_table_seek_ref(&fri->tab, &it, + ref->refname); + if (err == 0) { + err = reftable_iterator_next_ref(&it, ref); + } + + reftable_iterator_destroy(&it); + + if (err < 0) { + break; + } + + if (err > 0) { + continue; + } + } + + if ((ref->target_value != NULL && + !memcmp(fri->oid.buf, ref->target_value, fri->oid.len)) || + (ref->value != NULL && + !memcmp(fri->oid.buf, ref->value, fri->oid.len))) { + return 0; + } + } + + reftable_ref_record_release(ref); + return err; +} + +static struct reftable_iterator_vtable filtering_ref_iterator_vtable = { + .next = &filtering_ref_iterator_next, + .close = &filtering_ref_iterator_close, +}; + +void iterator_from_filtering_ref_iterator(struct reftable_iterator *it, + struct filtering_ref_iterator *fri) +{ + assert(it->ops == NULL); + it->iter_arg = fri; + it->ops = &filtering_ref_iterator_vtable; +} + +static void indexed_table_ref_iter_close(void *p) +{ + struct indexed_table_ref_iter *it = (struct indexed_table_ref_iter *)p; + block_iter_close(&it->cur); + reftable_block_done(&it->block_reader.block); + strbuf_release(&it->oid); +} + +static int indexed_table_ref_iter_next_block(struct indexed_table_ref_iter *it) +{ + uint64_t off; + int err = 0; + if (it->offset_idx == it->offset_len) { + it->is_finished = 1; + return 1; + } + + reftable_block_done(&it->block_reader.block); + + off = it->offsets[it->offset_idx++]; + err = reader_init_block_reader(it->r, &it->block_reader, off, + BLOCK_TYPE_REF); + if (err < 0) { + return err; + } + if (err > 0) { + /* indexed block does not exist. */ + return REFTABLE_FORMAT_ERROR; + } + block_reader_start(&it->block_reader, &it->cur); + return 0; +} + +static int indexed_table_ref_iter_next(void *p, struct reftable_record *rec) +{ + struct indexed_table_ref_iter *it = (struct indexed_table_ref_iter *)p; + struct reftable_ref_record *ref = + (struct reftable_ref_record *)rec->data; + + while (1) { + int err = block_iter_next(&it->cur, rec); + if (err < 0) { + return err; + } + + if (err > 0) { + err = indexed_table_ref_iter_next_block(it); + if (err < 0) { + return err; + } + + if (it->is_finished) { + return 1; + } + continue; + } + + if (!memcmp(it->oid.buf, ref->target_value, it->oid.len) || + !memcmp(it->oid.buf, ref->value, it->oid.len)) { + return 0; + } + } +} + +int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest, + struct reftable_reader *r, uint8_t *oid, + int oid_len, uint64_t *offsets, int offset_len) +{ + struct indexed_table_ref_iter empty = INDEXED_TABLE_REF_ITER_INIT; + struct indexed_table_ref_iter *itr = + reftable_calloc(sizeof(struct indexed_table_ref_iter)); + int err = 0; + + *itr = empty; + itr->r = r; + strbuf_add(&itr->oid, oid, oid_len); + + itr->offsets = offsets; + itr->offset_len = offset_len; + + err = indexed_table_ref_iter_next_block(itr); + if (err < 0) { + reftable_free(itr); + } else { + *dest = itr; + } + return err; +} + +static struct reftable_iterator_vtable indexed_table_ref_iter_vtable = { + .next = &indexed_table_ref_iter_next, + .close = &indexed_table_ref_iter_close, +}; + +void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it, + struct indexed_table_ref_iter *itr) +{ + assert(it->ops == NULL); + it->iter_arg = itr; + it->ops = &indexed_table_ref_iter_vtable; +} diff --git a/reftable/iter.h b/reftable/iter.h new file mode 100644 index 0000000000..258bc107af --- /dev/null +++ b/reftable/iter.h @@ -0,0 +1,75 @@ +/* +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 ITER_H +#define ITER_H + +#include "system.h" +#include "block.h" +#include "record.h" + +#include "reftable-iterator.h" +#include "reftable-generic.h" + +struct reftable_iterator_vtable { + int (*next)(void *iter_arg, struct reftable_record *rec); + void (*close)(void *iter_arg); +}; + +void iterator_set_empty(struct reftable_iterator *it); +int iterator_next(struct reftable_iterator *it, struct reftable_record *rec); + +/* Returns true for a zeroed out iterator, such as the one returned from + iterator_destroy. */ +int iterator_is_null(struct reftable_iterator *it); + +/* iterator that produces only ref records that point to `oid` */ +struct filtering_ref_iterator { + int double_check; + struct reftable_table tab; + struct strbuf oid; + struct reftable_iterator it; +}; +#define FILTERING_REF_ITERATOR_INIT \ + { \ + .oid = STRBUF_INIT \ + } + +void iterator_from_filtering_ref_iterator(struct reftable_iterator *, + struct filtering_ref_iterator *); + +/* iterator that produces only ref records that point to `oid`, + but using the object index. + */ +struct indexed_table_ref_iter { + struct reftable_reader *r; + struct strbuf oid; + + /* mutable */ + uint64_t *offsets; + + /* Points to the next offset to read. */ + int offset_idx; + int offset_len; + struct block_reader block_reader; + struct block_iter cur; + int is_finished; +}; + +#define INDEXED_TABLE_REF_ITER_INIT \ + { \ + .cur = { .last_key = STRBUF_INIT }, .oid = STRBUF_INIT, \ + } + +void iterator_from_indexed_table_ref_iter(struct reftable_iterator *it, + struct indexed_table_ref_iter *itr); +int new_indexed_table_ref_iter(struct indexed_table_ref_iter **dest, + struct reftable_reader *r, uint8_t *oid, + int oid_len, uint64_t *offsets, int offset_len); + +#endif diff --git a/reftable/reader.c b/reftable/reader.c new file mode 100644 index 0000000000..a5b7b1d4fe --- /dev/null +++ b/reftable/reader.c @@ -0,0 +1,733 @@ +/* +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 "reader.h" + +#include "system.h" +#include "block.h" +#include "constants.h" +#include "iter.h" +#include "record.h" +#include "reftable-error.h" +#include "tree.h" + +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) +{ + int result = source->ops->read_block(source->arg, dest, off, size); + dest->source = *source; + return result; +} + +void block_source_close(struct reftable_block_source *source) +{ + if (source->ops == NULL) { + return; + } + + source->ops->close(source->arg); + source->ops = NULL; +} + +static struct reftable_reader_offsets * +reader_offsets_for(struct reftable_reader *r, uint8_t typ) +{ + switch (typ) { + case BLOCK_TYPE_REF: + return &r->ref_offsets; + case BLOCK_TYPE_LOG: + return &r->log_offsets; + case BLOCK_TYPE_OBJ: + return &r->obj_offsets; + } + abort(); +} + +static int reader_get_block(struct reftable_reader *r, + struct reftable_block *dest, uint64_t off, + uint32_t sz) +{ + if (off >= r->size) + return 0; + + if (off + sz > r->size) { + sz = r->size - off; + } + + return block_source_read_block(&r->source, dest, off, sz); +} + +uint32_t reftable_reader_hash_id(struct reftable_reader *r) +{ + return r->hash_id; +} + +const char *reader_name(struct reftable_reader *r) +{ + return r->name; +} + +static int parse_footer(struct reftable_reader *r, uint8_t *footer, + uint8_t *header) +{ + uint8_t *f = footer; + uint8_t first_block_typ; + int err = 0; + uint32_t computed_crc; + uint32_t file_crc; + + if (memcmp(f, "REFT", 4)) { + err = REFTABLE_FORMAT_ERROR; + goto done; + } + f += 4; + + if (memcmp(footer, header, header_size(r->version))) { + err = REFTABLE_FORMAT_ERROR; + goto done; + } + + f++; + r->block_size = get_be24(f); + + f += 3; + r->min_update_index = get_be64(f); + f += 8; + r->max_update_index = get_be64(f); + f += 8; + + if (r->version == 1) { + r->hash_id = SHA1_ID; + } else { + r->hash_id = get_be32(f); + switch (r->hash_id) { + case SHA1_ID: + break; + case SHA256_ID: + break; + default: + err = REFTABLE_FORMAT_ERROR; + goto done; + } + f += 4; + } + + r->ref_offsets.index_offset = get_be64(f); + f += 8; + + r->obj_offsets.offset = get_be64(f); + f += 8; + + r->object_id_len = r->obj_offsets.offset & ((1 << 5) - 1); + r->obj_offsets.offset >>= 5; + + r->obj_offsets.index_offset = get_be64(f); + f += 8; + r->log_offsets.offset = get_be64(f); + f += 8; + r->log_offsets.index_offset = get_be64(f); + f += 8; + + computed_crc = crc32(0, footer, f - footer); + file_crc = get_be32(f); + f += 4; + if (computed_crc != file_crc) { + err = REFTABLE_FORMAT_ERROR; + goto done; + } + + first_block_typ = header[header_size(r->version)]; + r->ref_offsets.is_present = (first_block_typ == BLOCK_TYPE_REF); + r->ref_offsets.offset = 0; + r->log_offsets.is_present = (first_block_typ == BLOCK_TYPE_LOG || + r->log_offsets.offset > 0); + r->obj_offsets.is_present = r->obj_offsets.offset > 0; + err = 0; +done: + return err; +} + +int init_reader(struct reftable_reader *r, struct reftable_block_source *source, + const char *name) +{ + struct reftable_block footer = { NULL }; + struct reftable_block header = { NULL }; + int err = 0; + + memset(r, 0, sizeof(struct reftable_reader)); + + /* Need +1 to read type of first block. */ + err = block_source_read_block(source, &header, 0, header_size(2) + 1); + if (err != header_size(2) + 1) { + err = REFTABLE_IO_ERROR; + goto done; + } + + if (memcmp(header.data, "REFT", 4)) { + err = REFTABLE_FORMAT_ERROR; + goto done; + } + r->version = header.data[4]; + if (r->version != 1 && r->version != 2) { + err = REFTABLE_FORMAT_ERROR; + goto done; + } + + r->size = block_source_size(source) - footer_size(r->version); + r->source = *source; + r->name = xstrdup(name); + r->hash_id = 0; + + err = block_source_read_block(source, &footer, r->size, + footer_size(r->version)); + if (err != footer_size(r->version)) { + err = REFTABLE_IO_ERROR; + goto done; + } + + err = parse_footer(r, footer.data, header.data); +done: + reftable_block_done(&footer); + reftable_block_done(&header); + return err; +} + +struct table_iter { + struct reftable_reader *r; + uint8_t typ; + uint64_t block_off; + struct block_iter bi; + int is_finished; +}; +#define TABLE_ITER_INIT \ + { \ + .bi = {.last_key = STRBUF_INIT } \ + } + +static void table_iter_copy_from(struct table_iter *dest, + struct table_iter *src) +{ + dest->r = src->r; + dest->typ = src->typ; + dest->block_off = src->block_off; + dest->is_finished = src->is_finished; + block_iter_copy_from(&dest->bi, &src->bi); +} + +static int table_iter_next_in_block(struct table_iter *ti, + struct reftable_record *rec) +{ + int res = block_iter_next(&ti->bi, rec); + if (res == 0 && reftable_record_type(rec) == BLOCK_TYPE_REF) { + ((struct reftable_ref_record *)rec->data)->update_index += + ti->r->min_update_index; + } + + return res; +} + +static void table_iter_block_done(struct table_iter *ti) +{ + if (ti->bi.br == NULL) { + return; + } + reftable_block_done(&ti->bi.br->block); + FREE_AND_NULL(ti->bi.br); + + ti->bi.last_key.len = 0; + ti->bi.next_off = 0; +} + +static int32_t extract_block_size(uint8_t *data, uint8_t *typ, uint64_t off, + int version) +{ + int32_t result = 0; + + if (off == 0) { + data += header_size(version); + } + + *typ = data[0]; + if (reftable_is_block_type(*typ)) { + result = get_be24(data + 1); + } + return result; +} + +int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br, + uint64_t next_off, uint8_t want_typ) +{ + int32_t guess_block_size = r->block_size ? r->block_size : + DEFAULT_BLOCK_SIZE; + struct reftable_block block = { NULL }; + uint8_t block_typ = 0; + int err = 0; + uint32_t header_off = next_off ? 0 : header_size(r->version); + int32_t block_size = 0; + + if (next_off >= r->size) + return 1; + + err = reader_get_block(r, &block, next_off, guess_block_size); + if (err < 0) + return err; + + block_size = extract_block_size(block.data, &block_typ, next_off, + r->version); + if (block_size < 0) + return block_size; + + if (want_typ != BLOCK_TYPE_ANY && block_typ != want_typ) { + reftable_block_done(&block); + return 1; + } + + if (block_size > guess_block_size) { + reftable_block_done(&block); + err = reader_get_block(r, &block, next_off, block_size); + if (err < 0) { + return err; + } + } + + return block_reader_init(br, &block, header_off, r->block_size, + hash_size(r->hash_id)); +} + +static int table_iter_next_block(struct table_iter *dest, + struct table_iter *src) +{ + uint64_t next_block_off = src->block_off + src->bi.br->full_block_size; + struct block_reader br = { 0 }; + int err = 0; + + dest->r = src->r; + dest->typ = src->typ; + dest->block_off = next_block_off; + + err = reader_init_block_reader(src->r, &br, next_block_off, src->typ); + if (err > 0) { + dest->is_finished = 1; + return 1; + } + if (err != 0) + return err; + else { + struct block_reader *brp = + reftable_malloc(sizeof(struct block_reader)); + *brp = br; + + dest->is_finished = 0; + block_reader_start(brp, &dest->bi); + } + return 0; +} + +static int table_iter_next(struct table_iter *ti, struct reftable_record *rec) +{ + if (reftable_record_type(rec) != ti->typ) + return REFTABLE_API_ERROR; + + while (1) { + struct table_iter next = TABLE_ITER_INIT; + int err = 0; + if (ti->is_finished) { + return 1; + } + + err = table_iter_next_in_block(ti, rec); + if (err <= 0) { + return err; + } + + err = table_iter_next_block(&next, ti); + if (err != 0) { + ti->is_finished = 1; + } + table_iter_block_done(ti); + if (err != 0) { + return err; + } + table_iter_copy_from(ti, &next); + block_iter_close(&next.bi); + } +} + +static int table_iter_next_void(void *ti, struct reftable_record *rec) +{ + return table_iter_next((struct table_iter *)ti, rec); +} + +static void table_iter_close(void *p) +{ + struct table_iter *ti = (struct table_iter *)p; + table_iter_block_done(ti); + block_iter_close(&ti->bi); +} + +static struct reftable_iterator_vtable table_iter_vtable = { + .next = &table_iter_next_void, + .close = &table_iter_close, +}; + +static void iterator_from_table_iter(struct reftable_iterator *it, + struct table_iter *ti) +{ + assert(it->ops == NULL); + it->iter_arg = ti; + it->ops = &table_iter_vtable; +} + +static int reader_table_iter_at(struct reftable_reader *r, + struct table_iter *ti, uint64_t off, + uint8_t typ) +{ + struct block_reader br = { 0 }; + struct block_reader *brp = NULL; + + int err = reader_init_block_reader(r, &br, off, typ); + if (err != 0) + return err; + + brp = reftable_malloc(sizeof(struct block_reader)); + *brp = br; + ti->r = r; + ti->typ = block_reader_type(brp); + ti->block_off = off; + block_reader_start(brp, &ti->bi); + return 0; +} + +static int reader_start(struct reftable_reader *r, struct table_iter *ti, + uint8_t typ, int index) +{ + struct reftable_reader_offsets *offs = reader_offsets_for(r, typ); + uint64_t off = offs->offset; + if (index) { + off = offs->index_offset; + if (off == 0) { + return 1; + } + typ = BLOCK_TYPE_INDEX; + } + + return reader_table_iter_at(r, ti, off, typ); +} + +static int reader_seek_linear(struct reftable_reader *r, struct table_iter *ti, + struct reftable_record *want) +{ + struct reftable_record rec = + reftable_new_record(reftable_record_type(want)); + struct strbuf want_key = STRBUF_INIT; + struct strbuf got_key = STRBUF_INIT; + struct table_iter next = TABLE_ITER_INIT; + int err = -1; + + reftable_record_key(want, &want_key); + + while (1) { + err = table_iter_next_block(&next, ti); + if (err < 0) + goto done; + + if (err > 0) { + break; + } + + err = block_reader_first_key(next.bi.br, &got_key); + if (err < 0) + goto done; + + if (strbuf_cmp(&got_key, &want_key) > 0) { + table_iter_block_done(&next); + break; + } + + table_iter_block_done(ti); + table_iter_copy_from(ti, &next); + } + + err = block_iter_seek(&ti->bi, &want_key); + if (err < 0) + goto done; + err = 0; + +done: + block_iter_close(&next.bi); + reftable_record_destroy(&rec); + strbuf_release(&want_key); + strbuf_release(&got_key); + return err; +} + +static int reader_seek_indexed(struct reftable_reader *r, + struct reftable_iterator *it, + struct reftable_record *rec) +{ + struct reftable_index_record want_index = { .last_key = STRBUF_INIT }; + struct reftable_record want_index_rec = { NULL }; + struct reftable_index_record index_result = { .last_key = STRBUF_INIT }; + struct reftable_record index_result_rec = { NULL }; + struct table_iter index_iter = TABLE_ITER_INIT; + struct table_iter next = TABLE_ITER_INIT; + int err = 0; + + reftable_record_key(rec, &want_index.last_key); + reftable_record_from_index(&want_index_rec, &want_index); + reftable_record_from_index(&index_result_rec, &index_result); + + err = reader_start(r, &index_iter, reftable_record_type(rec), 1); + if (err < 0) + goto done; + + err = reader_seek_linear(r, &index_iter, &want_index_rec); + while (1) { + err = table_iter_next(&index_iter, &index_result_rec); + table_iter_block_done(&index_iter); + if (err != 0) + goto done; + + err = reader_table_iter_at(r, &next, index_result.offset, 0); + if (err != 0) + goto done; + + err = block_iter_seek(&next.bi, &want_index.last_key); + if (err < 0) + goto done; + + if (next.typ == reftable_record_type(rec)) { + err = 0; + break; + } + + if (next.typ != BLOCK_TYPE_INDEX) { + err = REFTABLE_FORMAT_ERROR; + break; + } + + table_iter_copy_from(&index_iter, &next); + } + + if (err == 0) { + struct table_iter empty = TABLE_ITER_INIT; + struct table_iter *malloced = + reftable_calloc(sizeof(struct table_iter)); + *malloced = empty; + table_iter_copy_from(malloced, &next); + iterator_from_table_iter(it, malloced); + } +done: + block_iter_close(&next.bi); + table_iter_close(&index_iter); + reftable_record_release(&want_index_rec); + reftable_record_release(&index_result_rec); + return err; +} + +static int reader_seek_internal(struct reftable_reader *r, + struct reftable_iterator *it, + struct reftable_record *rec) +{ + struct reftable_reader_offsets *offs = + reader_offsets_for(r, reftable_record_type(rec)); + uint64_t idx = offs->index_offset; + struct table_iter ti = TABLE_ITER_INIT; + int err = 0; + if (idx > 0) + return reader_seek_indexed(r, it, rec); + + err = reader_start(r, &ti, reftable_record_type(rec), 0); + if (err < 0) + return err; + err = reader_seek_linear(r, &ti, rec); + if (err < 0) + return err; + else { + struct table_iter *p = + reftable_malloc(sizeof(struct table_iter)); + *p = ti; + iterator_from_table_iter(it, p); + } + + return 0; +} + +int reader_seek(struct reftable_reader *r, struct reftable_iterator *it, + struct reftable_record *rec) +{ + uint8_t typ = reftable_record_type(rec); + + struct reftable_reader_offsets *offs = reader_offsets_for(r, typ); + if (!offs->is_present) { + iterator_set_empty(it); + return 0; + } + + return reader_seek_internal(r, it, rec); +} + +int reftable_reader_seek_ref(struct reftable_reader *r, + struct reftable_iterator *it, const char *name) +{ + struct reftable_ref_record ref = { + .refname = (char *)name, + }; + struct reftable_record rec = { NULL }; + reftable_record_from_ref(&rec, &ref); + return reader_seek(r, it, &rec); +} + +int reftable_reader_seek_log_at(struct reftable_reader *r, + struct reftable_iterator *it, const char *name, + uint64_t update_index) +{ + struct reftable_log_record log = { + .refname = (char *)name, + .update_index = update_index, + }; + struct reftable_record rec = { NULL }; + reftable_record_from_log(&rec, &log); + return reader_seek(r, it, &rec); +} + +int reftable_reader_seek_log(struct reftable_reader *r, + struct reftable_iterator *it, const char *name) +{ + uint64_t max = ~((uint64_t)0); + return reftable_reader_seek_log_at(r, it, name, max); +} + +void reader_close(struct reftable_reader *r) +{ + block_source_close(&r->source); + FREE_AND_NULL(r->name); +} + +int reftable_new_reader(struct reftable_reader **p, + struct reftable_block_source *src, char const *name) +{ + struct reftable_reader *rd = + reftable_calloc(sizeof(struct reftable_reader)); + int err = init_reader(rd, src, name); + if (err == 0) { + *p = rd; + } else { + block_source_close(src); + reftable_free(rd); + } + return err; +} + +void reftable_reader_free(struct reftable_reader *r) +{ + reader_close(r); + reftable_free(r); +} + +static int reftable_reader_refs_for_indexed(struct reftable_reader *r, + struct reftable_iterator *it, + uint8_t *oid) +{ + struct reftable_obj_record want = { + .hash_prefix = oid, + .hash_prefix_len = r->object_id_len, + }; + struct reftable_record want_rec = { NULL }; + struct reftable_iterator oit = { NULL }; + struct reftable_obj_record got = { NULL }; + struct reftable_record got_rec = { NULL }; + int err = 0; + struct indexed_table_ref_iter *itr = NULL; + + /* Look through the reverse index. */ + reftable_record_from_obj(&want_rec, &want); + err = reader_seek(r, &oit, &want_rec); + if (err != 0) + goto done; + + /* read out the reftable_obj_record */ + reftable_record_from_obj(&got_rec, &got); + err = iterator_next(&oit, &got_rec); + if (err < 0) + goto done; + + if (err > 0 || + memcmp(want.hash_prefix, got.hash_prefix, r->object_id_len)) { + /* didn't find it; return empty iterator */ + iterator_set_empty(it); + err = 0; + goto done; + } + + err = new_indexed_table_ref_iter(&itr, r, oid, hash_size(r->hash_id), + got.offsets, got.offset_len); + if (err < 0) + goto done; + got.offsets = NULL; + iterator_from_indexed_table_ref_iter(it, itr); + +done: + reftable_iterator_destroy(&oit); + reftable_record_release(&got_rec); + return err; +} + +static int reftable_reader_refs_for_unindexed(struct reftable_reader *r, + struct reftable_iterator *it, + uint8_t *oid) +{ + struct table_iter ti_empty = TABLE_ITER_INIT; + struct table_iter *ti = reftable_calloc(sizeof(struct table_iter)); + struct filtering_ref_iterator *filter = NULL; + struct filtering_ref_iterator empty = FILTERING_REF_ITERATOR_INIT; + int oid_len = hash_size(r->hash_id); + int err; + + *ti = ti_empty; + err = reader_start(r, ti, BLOCK_TYPE_REF, 0); + if (err < 0) { + reftable_free(ti); + return err; + } + + filter = reftable_malloc(sizeof(struct filtering_ref_iterator)); + *filter = empty; + + strbuf_add(&filter->oid, oid, oid_len); + reftable_table_from_reader(&filter->tab, r); + filter->double_check = 0; + iterator_from_table_iter(&filter->it, ti); + + iterator_from_filtering_ref_iterator(it, filter); + return 0; +} + +int reftable_reader_refs_for(struct reftable_reader *r, + struct reftable_iterator *it, uint8_t *oid) +{ + if (r->obj_offsets.is_present) + return reftable_reader_refs_for_indexed(r, it, oid); + return reftable_reader_refs_for_unindexed(r, it, oid); +} + +uint64_t reftable_reader_max_update_index(struct reftable_reader *r) +{ + return r->max_update_index; +} + +uint64_t reftable_reader_min_update_index(struct reftable_reader *r) +{ + return r->min_update_index; +} diff --git a/reftable/reader.h b/reftable/reader.h new file mode 100644 index 0000000000..6d4927e1c5 --- /dev/null +++ b/reftable/reader.h @@ -0,0 +1,75 @@ +/* +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 READER_H +#define READER_H + +#include "block.h" +#include "record.h" +#include "reftable-iterator.h" +#include "reftable-reader.h" + +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); +void block_source_close(struct reftable_block_source *source); + +/* metadata for a block type */ +struct reftable_reader_offsets { + int is_present; + uint64_t offset; + uint64_t index_offset; +}; + +/* The state for reading a reftable file. */ +struct reftable_reader { + /* for convience, associate a name with the instance. */ + char *name; + struct reftable_block_source source; + + /* Size of the file, excluding the footer. */ + uint64_t size; + + /* 'sha1' for SHA1, 's256' for SHA-256 */ + uint32_t hash_id; + + uint32_t block_size; + uint64_t min_update_index; + uint64_t max_update_index; + /* Length of the OID keys in the 'o' section */ + int object_id_len; + int version; + + struct reftable_reader_offsets ref_offsets; + struct reftable_reader_offsets obj_offsets; + struct reftable_reader_offsets log_offsets; +}; + +int init_reader(struct reftable_reader *r, struct reftable_block_source *source, + const char *name); +int reader_seek(struct reftable_reader *r, struct reftable_iterator *it, + struct reftable_record *rec); +void reader_close(struct reftable_reader *r); +const char *reader_name(struct reftable_reader *r); + +/* initialize a block reader to read from `r` */ +int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br, + uint64_t next_off, uint8_t want_typ); + +/* generic interface to reftables */ +struct reftable_table_vtable { + int (*seek_record)(void *tab, struct reftable_iterator *it, + struct reftable_record *); + uint32_t (*hash_id)(void *tab); + uint64_t (*min_update_index)(void *tab); + uint64_t (*max_update_index)(void *tab); +}; + +#endif diff --git a/reftable/reftable-iterator.h b/reftable/reftable-iterator.h new file mode 100644 index 0000000000..a3d6be7ae0 --- /dev/null +++ b/reftable/reftable-iterator.h @@ -0,0 +1,37 @@ +/* +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_ITERATOR_H +#define REFTABLE_ITERATOR_H + +#include "reftable-record.h" + +/* iterator is the generic interface for walking over data stored in a + reftable. +*/ +struct reftable_iterator { + struct reftable_iterator_vtable *ops; + void *iter_arg; +}; + +/* reads the next reftable_ref_record. Returns < 0 for error, 0 for OK and > 0: + end of iteration. +*/ +int reftable_iterator_next_ref(struct reftable_iterator *it, + struct reftable_ref_record *ref); + +/* reads the next reftable_log_record. Returns < 0 for error, 0 for OK and > 0: + end of iteration. +*/ +int reftable_iterator_next_log(struct reftable_iterator *it, + struct reftable_log_record *log); + +/* releases resources associated with an iterator. */ +void reftable_iterator_destroy(struct reftable_iterator *it); + +#endif diff --git a/reftable/reftable-reader.h b/reftable/reftable-reader.h new file mode 100644 index 0000000000..827957a8fb --- /dev/null +++ b/reftable/reftable-reader.h @@ -0,0 +1,89 @@ +/* +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_READER_H +#define REFTABLE_READER_H + +#include "reftable-iterator.h" +#include "reftable-blocksource.h" + +/* + Reading single tables + + The follow routines are for reading single files. For an application-level + interface, skip ahead to struct reftable_merged_table and struct + reftable_stack. +*/ + +/* The reader struct is a handle to an open reftable file. */ +struct reftable_reader; + +/* reftable_new_reader opens a reftable for reading. If successful, returns 0 + * code and sets pp. The name is used for creating a stack. Typically, it is the + * basename of the file. The block source `src` is owned by the reader, and is + * closed on calling reftable_reader_destroy(). + */ +int reftable_new_reader(struct reftable_reader **pp, + struct reftable_block_source *src, const char *name); + +/* reftable_reader_seek_ref returns an iterator where 'name' would be inserted + in the table. To seek to the start of the table, use name = "". + + example: + + struct reftable_reader *r = NULL; + int err = reftable_new_reader(&r, &src, "filename"); + if (err < 0) { ... } + struct reftable_iterator it = {0}; + err = reftable_reader_seek_ref(r, &it, "refs/heads/master"); + if (err < 0) { ... } + struct reftable_ref_record ref = {0}; + while (1) { + err = reftable_iterator_next_ref(&it, &ref); + if (err > 0) { + break; + } + if (err < 0) { + ..error handling.. + } + ..found.. + } + reftable_iterator_destroy(&it); + reftable_ref_record_release(&ref); + */ +int reftable_reader_seek_ref(struct reftable_reader *r, + struct reftable_iterator *it, const char *name); + +/* returns the hash ID used in this table. */ +uint32_t reftable_reader_hash_id(struct reftable_reader *r); + +/* seek to logs for the given name, older than update_index. To seek to the + start of the table, use name = "". + */ +int reftable_reader_seek_log_at(struct reftable_reader *r, + struct reftable_iterator *it, const char *name, + uint64_t update_index); + +/* seek to newest log entry for given name. */ +int reftable_reader_seek_log(struct reftable_reader *r, + struct reftable_iterator *it, const char *name); + +/* closes and deallocates a reader. */ +void reftable_reader_free(struct reftable_reader *); + +/* return an iterator for the refs pointing to `oid`. */ +int reftable_reader_refs_for(struct reftable_reader *r, + struct reftable_iterator *it, uint8_t *oid); + +/* return the max_update_index for a table */ +uint64_t reftable_reader_max_update_index(struct reftable_reader *r); + +/* return the min_update_index for a table */ +uint64_t reftable_reader_min_update_index(struct reftable_reader *r); + +#endif -- gitgitgadget
