1 files changed, 159 insertions, 0 deletions
diff --git a/include/abuf.h b/include/abuf.h
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+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Handles a buffer that can be allocated and freed
+ *
+ * Copyright 2021 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __ABUF_H
+#define __ABUF_H
+
+#include <linux/types.h>
+
+/**
+ * struct abuf - buffer that can be allocated and freed
+ *
+ * This is useful for a block of data which may be allocated with malloc(), or
+ * not, so that it needs to be freed correctly when finished with.
+ *
+ * For now it has a very simple purpose.
+ *
+ * Using memset() to zero all fields is guaranteed to be equivalent to
+ * abuf_init().
+ *
+ * @data: Pointer to data
+ * @size: Size of data in bytes
+ * @alloced: true if allocated with malloc(), so must be freed after use
+ */
+struct abuf {
+	void *data;
+	size_t size;
+	bool alloced;
+};
+
+static inline void *abuf_data(const struct abuf *abuf)
+{
+	return abuf->data;
+}
+
+static inline size_t abuf_size(const struct abuf *abuf)
+{
+	return abuf->size;
+}
+
+/**
+ * abuf_set() - set the (unallocated) data in a buffer
+ *
+ * This simply makes the abuf point to the supplied data, which must be live
+ * for the lifetime of the abuf. It is not alloced.
+ *
+ * Any existing data in the abuf is freed and the alloced member is set to
+ * false.
+ *
+ * @abuf: abuf to adjust
+ * @data: New contents of abuf
+ * @size: New size of abuf
+ */
+void abuf_set(struct abuf *abuf, void *data, size_t size);
+
+/**
+ * abuf_map_sysmem() - calls map_sysmem() to set up an abuf
+ *
+ * This is equivalent to abuf_set(abuf, map_sysmem(addr, size), size)
+ *
+ * Any existing data in the abuf is freed and the alloced member is set to
+ * false.
+ *
+ * @abuf: abuf to adjust
+ * @addr: Address to set the abuf to
+ * @size: New size of abuf
+ */
+void abuf_map_sysmem(struct abuf *abuf, ulong addr, size_t size);
+
+/**
+ * abuf_realloc() - Change the size of a buffer
+ *
+ * This uses realloc() to change the size of the buffer, with the same semantics
+ * as that function. If the abuf is not currently alloced, then it will alloc
+ * it if the size needs to increase (i.e. set the alloced member to true)
+ *
+ * @abuf: abuf to adjust
+ * @new_size: new size in bytes.
+ *	if 0, the abuf is freed
+ *	if greater than the current size, the abuf is extended and the new
+ *	   space is not inited. The alloced member is set to true
+ *	if less than the current size, the abuf is contracted and the data at
+ *	   the end is lost. If @new_size is 0, this sets the alloced member to
+ *	   false
+ * Return: true if OK, false if out of memory
+ */
+bool abuf_realloc(struct abuf *abuf, size_t new_size);
+
+/**
+ * abuf_uninit_move() - Return the allocated contents and uninit the abuf
+ *
+ * This returns the abuf data to the caller, allocating it if necessary, so that
+ * the caller receives data that it can be sure will hang around. The caller is
+ * responsible for freeing the data.
+ *
+ * If the abuf has allocated data, it is returned. If the abuf has data but it
+ * is not allocated, then it is first allocated, then returned.
+ *
+ * If the abuf size is 0, this returns NULL
+ *
+ * The abuf is uninited as part of this, except if the allocation fails, in
+ * which NULL is returned and the abuf remains untouched.
+ *
+ * The abuf must be inited before this can be called.
+ *
+ * @abuf: abuf to uninit
+ * @sizep: if non-NULL, returns the size of the returned data
+ * Return: data contents, allocated with malloc(), or NULL if the data could not
+ *	be allocated, or the data size is 0
+ */
+void *abuf_uninit_move(struct abuf *abuf, size_t *sizep);
+
+/**
+ * abuf_init_move() - Make abuf take over the management of an allocated region
+ *
+ * After this, @data must not be used. All access must be via the abuf.
+ *
+ * @abuf: abuf to init
+ * @data: Existing allocated buffer to place in the abuf
+ * @size: Size of allocated buffer
+ */
+void abuf_init_move(struct abuf *abuf, void *data, size_t size);
+
+/**
+ * abuf_init_set() - Set up a new abuf
+ *
+ * Inits a new abuf and sets up its (unallocated) data
+ *
+ * @abuf: abuf to set up
+ * @data: New contents of abuf
+ * @size: New size of abuf
+ */
+void abuf_init_set(struct abuf *abuf, void *data, size_t size);
+
+/**
+ * abuf_uninit() - Free any memory used by an abuf
+ *
+ * The buffer must be inited before this can be called.
+ *
+ * @abuf: abuf to uninit
+ */
+void abuf_uninit(struct abuf *abuf);
+
+/**
+ * abuf_init() - Set up a new abuf
+ *
+ * This initially has no data and alloced is set to false. This is equivalent to
+ * setting all fields to 0, e.g. with memset(), so callers can do that instead
+ * if desired.
+ *
+ * @abuf: abuf to set up
+ */
+void abuf_init(struct abuf *abuf);
+
+#endif