@@ -2451,6 +2451,7 @@ xdiff-objs: $(XDIFF_OBJS)
REFTABLE_OBJS += reftable/basics.o
REFTABLE_OBJS += reftable/error.o
+REFTABLE_OBJS += reftable/blocksource.o
REFTABLE_OBJS += reftable/publicbasics.o
REFTABLE_TEST_OBJS += reftable/test_framework.o
new file mode 100644
@@ -0,0 +1,148 @@
+/*
+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 "system.h"
+
+#include "basics.h"
+#include "blocksource.h"
+#include "reftable-blocksource.h"
+#include "reftable-error.h"
+
+static void strbuf_return_block(void *b, struct reftable_block *dest)
+{
+ memset(dest->data, 0xff, dest->len);
+ reftable_free(dest->data);
+}
+
+static void strbuf_close(void *b)
+{
+}
+
+static int strbuf_read_block(void *v, struct reftable_block *dest, uint64_t off,
+ uint32_t size)
+{
+ struct strbuf *b = v;
+ assert(off + size <= b->len);
+ dest->data = reftable_calloc(size);
+ memcpy(dest->data, b->buf + off, size);
+ dest->len = size;
+ return size;
+}
+
+static uint64_t strbuf_size(void *b)
+{
+ return ((struct strbuf *)b)->len;
+}
+
+static struct reftable_block_source_vtable strbuf_vtable = {
+ .size = &strbuf_size,
+ .read_block = &strbuf_read_block,
+ .return_block = &strbuf_return_block,
+ .close = &strbuf_close,
+};
+
+void block_source_from_strbuf(struct reftable_block_source *bs,
+ struct strbuf *buf)
+{
+ assert(!bs->ops);
+ bs->ops = &strbuf_vtable;
+ bs->arg = buf;
+}
+
+static void malloc_return_block(void *b, struct reftable_block *dest)
+{
+ memset(dest->data, 0xff, dest->len);
+ reftable_free(dest->data);
+}
+
+static struct reftable_block_source_vtable malloc_vtable = {
+ .return_block = &malloc_return_block,
+};
+
+static struct reftable_block_source malloc_block_source_instance = {
+ .ops = &malloc_vtable,
+};
+
+struct reftable_block_source malloc_block_source(void)
+{
+ return malloc_block_source_instance;
+}
+
+struct file_block_source {
+ int fd;
+ uint64_t size;
+};
+
+static uint64_t file_size(void *b)
+{
+ return ((struct file_block_source *)b)->size;
+}
+
+static void file_return_block(void *b, struct reftable_block *dest)
+{
+ memset(dest->data, 0xff, dest->len);
+ reftable_free(dest->data);
+}
+
+static void file_close(void *b)
+{
+ int fd = ((struct file_block_source *)b)->fd;
+ if (fd > 0) {
+ close(fd);
+ ((struct file_block_source *)b)->fd = 0;
+ }
+
+ reftable_free(b);
+}
+
+static int 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);
+ dest->data = reftable_malloc(size);
+ if (pread(b->fd, dest->data, size, off) != size)
+ return -1;
+ dest->len = size;
+ return size;
+}
+
+static struct reftable_block_source_vtable file_vtable = {
+ .size = &file_size,
+ .read_block = &file_read_block,
+ .return_block = &file_return_block,
+ .close = &file_close,
+};
+
+int reftable_block_source_from_file(struct reftable_block_source *bs,
+ const char *name)
+{
+ struct stat st = { 0 };
+ int err = 0;
+ int fd = open(name, O_RDONLY);
+ struct file_block_source *p = NULL;
+ if (fd < 0) {
+ if (errno == ENOENT) {
+ return REFTABLE_NOT_EXIST_ERROR;
+ }
+ return -1;
+ }
+
+ err = fstat(fd, &st);
+ if (err < 0)
+ return -1;
+
+ p = reftable_calloc(sizeof(struct file_block_source));
+ p->size = st.st_size;
+ p->fd = fd;
+
+ assert(!bs->ops);
+ bs->ops = &file_vtable;
+ bs->arg = p;
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,22 @@
+/*
+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 BLOCKSOURCE_H
+#define BLOCKSOURCE_H
+
+#include "system.h"
+
+struct reftable_block_source;
+
+/* Create an in-memory block source for reading reftables */
+void block_source_from_strbuf(struct reftable_block_source *bs,
+ struct strbuf *buf);
+
+struct reftable_block_source malloc_block_source(void);
+
+#endif
new file mode 100644
@@ -0,0 +1,49 @@
+/*
+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_BLOCKSOURCE_H
+#define REFTABLE_BLOCKSOURCE_H
+
+#include <stdint.h>
+
+/* block_source is a generic wrapper for a seekable readable file.
+ */
+struct reftable_block_source {
+ struct reftable_block_source_vtable *ops;
+ void *arg;
+};
+
+/* a contiguous segment of bytes. It keeps track of its generating block_source
+ * so it can return itself into the pool. */
+struct reftable_block {
+ uint8_t *data;
+ int len;
+ struct reftable_block_source source;
+};
+
+/* block_source_vtable are the operations that make up block_source */
+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);
+ /* mark the block as read; may return the data back to malloc */
+ void (*return_block)(void *source, struct reftable_block *blockp);
+
+ /* release all resources associated with the block source */
+ void (*close)(void *source);
+};
+
+/* opens a file on the file system as a block_source */
+int reftable_block_source_from_file(struct reftable_block_source *block_src,
+ const char *name);
+
+#endif