1 files changed, 179 insertions, 0 deletions
diff --git a/reftable/blocksource.c b/reftable/blocksource.c
new file mode 100644
index 0000000000..573c81287f
--- /dev/null
+++ b/reftable/blocksource.c
@@ -0,0 +1,179 @@
+/*
+ * 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"
+
+void block_source_release_data(struct reftable_block_data *data)
+{
+	struct reftable_block_source source = data->source;
+	if (data && source.ops)
+		source.ops->release_data(source.arg, data);
+	data->data = NULL;
+	data->len = 0;
+	data->source.ops = NULL;
+	data->source.arg = NULL;
+}
+
+void block_source_close(struct reftable_block_source *source)
+{
+	if (!source->ops) {
+		return;
+	}
+
+	source->ops->close(source->arg);
+	source->ops = NULL;
+}
+
+ssize_t block_source_read_data(struct reftable_block_source *source,
+			       struct reftable_block_data *dest, uint64_t off,
+			       uint32_t size)
+{
+	ssize_t result = source->ops->read_data(source->arg, dest, off, size);
+	dest->source = *source;
+	return result;
+}
+
+uint64_t block_source_size(struct reftable_block_source *source)
+{
+	return source->ops->size(source->arg);
+}
+
+static void reftable_buf_release_data(void *b REFTABLE_UNUSED, struct reftable_block_data *dest)
+{
+	if (dest->len)
+		memset(dest->data, 0xff, dest->len);
+	reftable_free(dest->data);
+}
+
+static void reftable_buf_close(void *b REFTABLE_UNUSED)
+{
+}
+
+static ssize_t reftable_buf_read_data(void *v, struct reftable_block_data *dest,
+				      uint64_t off, uint32_t size)
+{
+	struct reftable_buf *b = v;
+	assert(off + size <= b->len);
+	REFTABLE_CALLOC_ARRAY(dest->data, size);
+	if (!dest->data)
+		return -1;
+	memcpy(dest->data, b->buf + off, size);
+	dest->len = size;
+	return size;
+}
+
+static uint64_t reftable_buf_size(void *b)
+{
+	return ((struct reftable_buf *)b)->len;
+}
+
+static struct reftable_block_source_vtable reftable_buf_vtable = {
+	.size = &reftable_buf_size,
+	.read_data = &reftable_buf_read_data,
+	.release_data = &reftable_buf_release_data,
+	.close = &reftable_buf_close,
+};
+
+void block_source_from_buf(struct reftable_block_source *bs,
+			   struct reftable_buf *buf)
+{
+	assert(!bs->ops);
+	bs->ops = &reftable_buf_vtable;
+	bs->arg = buf;
+}
+
+struct file_block_source {
+	uint64_t size;
+	unsigned char *data;
+};
+
+static uint64_t file_size(void *b)
+{
+	return ((struct file_block_source *)b)->size;
+}
+
+static void file_release_data(void *b REFTABLE_UNUSED, struct reftable_block_data *dest REFTABLE_UNUSED)
+{
+}
+
+static void file_close(void *v)
+{
+	struct file_block_source *b = v;
+	munmap(b->data, b->size);
+	reftable_free(b);
+}
+
+static ssize_t file_read_data(void *v, struct reftable_block_data *dest, uint64_t off,
+			      uint32_t size)
+{
+	struct file_block_source *b = v;
+	assert(off + size <= b->size);
+	dest->data = b->data + off;
+	dest->len = size;
+	return size;
+}
+
+static struct reftable_block_source_vtable file_vtable = {
+	.size = &file_size,
+	.read_data = &file_read_data,
+	.release_data = &file_release_data,
+	.close = &file_close,
+};
+
+int reftable_block_source_from_file(struct reftable_block_source *bs,
+				    const char *name)
+{
+	struct file_block_source *p = NULL;
+	struct stat st;
+	int fd, err;
+
+	fd = open(name, O_RDONLY);
+	if (fd < 0) {
+		if (errno == ENOENT)
+			return REFTABLE_NOT_EXIST_ERROR;
+		err = -1;
+		goto out;
+	}
+
+	if (fstat(fd, &st) < 0) {
+		err = REFTABLE_IO_ERROR;
+		goto out;
+	}
+
+	REFTABLE_CALLOC_ARRAY(p, 1);
+	if (!p) {
+		err = REFTABLE_OUT_OF_MEMORY_ERROR;
+		goto out;
+	}
+
+	p->size = st.st_size;
+	p->data = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	if (p->data == MAP_FAILED) {
+		err = REFTABLE_IO_ERROR;
+		p->data = NULL;
+		goto out;
+	}
+
+	assert(!bs->ops);
+	bs->ops = &file_vtable;
+	bs->arg = p;
+
+	err = 0;
+
+out:
+	if (fd >= 0)
+		close(fd);
+	if (err < 0)
+		reftable_free(p);
+	return err;
+}