Add IO abstraction framework

This is intended primarily for use as a storage abstraction.
It allows operations such as image-loading to be implemented
in a platform-independent fashion.  Each platform registers
a set of IO drivers during initialisation.  The platform must
also provide a function that will return a device and a specifier
that can be used to access specified content.

Clients of the API will primarily use device and entity handles.
The term "entity" is deliberately vague, to allow for different
representations of content accessed using different types of
specifier, but will often be interpreted as a "file" where the
specifier will normally be its path.

This commit builds, but is intended to be paired with a sample
implementation of "load_image" using a semi-hosting driver on FVP.

Change-Id: Id3b52f1c0eb9ce76b44b99fc6b6460803668cc86

2 files changed, 130 insertions, 0 deletions

diff --git a/include/io_storage.h b/include/io_storage.h
new file mode 100644
index 0000000..71f5d26
--- /dev/null
+++ b/include/io_storage.h
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __IO_H__
+#define __IO_H__
+
+#include <stdint.h>
+#include <stdio.h>	/* For ssize_t */
+
+
+/* Device type which can be used to enable policy decisions about which device
+ * to access */
+typedef enum {
+	IO_TYPE_INVALID,
+	IO_TYPE_SEMIHOSTING,
+	IO_TYPE_BLOCK,
+	IO_TYPE_MAX
+} io_type;
+
+
+/* Modes used when seeking data on a supported device */
+typedef enum {
+	IO_SEEK_INVALID,
+	IO_SEEK_SET,
+	IO_SEEK_END,
+	IO_SEEK_CUR,
+	IO_SEEK_MAX
+} io_seek_mode;
+
+
+/* Connector type, providing a means of identifying a device to open */
+struct io_dev_connector;
+
+/* Device handle, providing a client with access to a specific device */
+typedef struct io_dev_info *io_dev_handle;
+
+/* IO handle, providing a client with access to a specific source of data from
+ * a device */
+typedef struct io_entity *io_handle;
+
+
+/* File specification - used to refer to data on a device supporting file-like
+ * entities */
+typedef struct {
+	const char *path;
+	unsigned int mode;
+} io_file_spec;
+
+
+/* Block specification - used to refer to data on a device supporting
+ * block-like entities */
+typedef struct {
+	unsigned long offset;
+	size_t length;
+} io_block_spec;
+
+
+/* Access modes used when accessing data on a device */
+#define IO_MODE_INVALID (0)
+#define IO_MODE_RO	(1 << 0)
+#define IO_MODE_RW	(1 << 1)
+
+
+/* Return codes reported by 'io_*' APIs */
+#define IO_SUCCESS		(0)
+#define IO_FAIL			(-1)
+#define IO_NOT_SUPPORTED	(-2)
+#define IO_RESOURCES_EXHAUSTED	(-3)
+
+
+/* Open a connection to a device */
+int io_dev_open(struct io_dev_connector *dev_con, void *dev_spec,
+		io_dev_handle *dev_handle);
+
+
+/* Initialise a device explicitly - to permit lazy initialisation or
+ * re-initialisation */
+int io_dev_init(io_dev_handle dev_handle, const void *init_params);
+
+/* TODO: Consider whether an explicit "shutdown" API should be included */
+
+/* Close a connection to a device */
+int io_dev_close(io_dev_handle dev_handle);
+
+
+/* Synchronous operations */
+int io_open(io_dev_handle dev_handle, const void *spec, io_handle *handle);
+
+int io_seek(io_handle handle, io_seek_mode mode, ssize_t offset);
+
+int io_size(io_handle handle, size_t *length);
+
+int io_read(io_handle handle, void *buffer, size_t length, size_t *length_read);
+
+int io_write(io_handle handle, const void *buffer, size_t length,
+		size_t *length_written);
+
+int io_close(io_handle handle);
+
+
+#endif /* __IO_H__ */
diff --git a/include/stdlib/string.h b/include/stdlib/string.h
index 221de03..00a5dcd 100644
--- a/include/stdlib/string.h
+++ b/include/stdlib/string.h
@@ -56,7 +56,9 @@ void	*memmove(void *, const void *, size_t);
 void	*memset(void *, int, size_t);
 
 char	*strchr(const char *, int) __pure;
+int	 strcmp(const char *, const char *) __pure;
 size_t	 strlen(const char *) __pure;
+int	 strncmp(const char *, const char *, size_t) __pure;
 
 __END_DECLS