sys/vfs_util: add VFS helper functions

sys/include/vfs_util.h

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2021 ML!PA Consulting GmbH
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @defgroup    sys_vfs_util    VFS helper functions
+ * @ingroup     sys_vfs
+ * @{
+ *
+ * @file
+ * @brief       VFS helper functions
+ *
+ * @author      Benjamin Valentin <[email protected]>
+ */
+
+#ifndef VFS_UTIL_H
+#define VFS_UTIL_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Writes the content of a buffer to a file
+ *          If the file already exists, it will be overwritten.
+ *
+ * @param[in]  file     Destination file path
+ * @param[in]  buf      Source buffer
+ * @param[in]  len      Buffer size
+ *
+ * @return  0 on success
+ * @return  negative error
+ */
+int vfs_file_from_buffer(const char *file, const void *buf, size_t len);
+
+/**
+ * @brief   Reads the content of a file to a buffer
+ *
+ * @param[in]  file     Source file path
+ * @param[out] buf      Destination buffer
+ * @param[in]  len      Buffer size
+ *
+ * @return  number of bytes read on success
+ * @return  negative error
+ */
+int vfs_file_to_buffer(const char* file, void* buf, size_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* VFS_UTIL_H */
+/** @} */

sys/vfs_util/Makefile

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+include $(RIOTBASE)/Makefile.base

sys/vfs_util/vfs_util.c

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+/*
+ * Copyright (C) 2021 Benjamin Valentin
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     sys_vfs_util
+ * @{
+ * @file
+ * @brief   VFS layer helper functions
+ * @author  Benjamin Valentin <[email protected]>
+ * @}
+ */
+
+#include <fcntl.h>
+#include <string.h>
+
+#include "vfs.h"
+#include "vfs_util.h"
+
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
+int vfs_file_from_buffer(const char *file, const void *buf, size_t len)
+{
+    int res, fd = vfs_open(file, O_CREAT | O_TRUNC | O_WRONLY, 0644);
+
+    if (fd < 0) {
+        DEBUG("can't open %s for writing\n", file);
+        return fd;
+    }
+
+    res = vfs_write(fd, buf, len);
+    vfs_close(fd);
+
+    if (res) {
+        return res;
+    }
+
+    return 0;
+}
+
+int vfs_file_to_buffer(const char* file, void* buf, size_t len)
+{
+    int res, fd = vfs_open(file, O_RDONLY, 0);
+
+    if (fd < 0) {
+        DEBUG("can't open %s for reading\n", file);
+        return fd;
+    }
+
+    res = vfs_read(fd, buf, len);
+    vfs_close(fd);
+
+    if (res > 0 && res < (int)len) {
+        memset((char *)buf + res, 0, len - res);
+    }
+
+    return res;
+}