nanocoap_vfs: add nanocoap_vfs_get()

sys/Makefile.dep

@@ -682,6 +682,11 @@ ifneq (,$(filter nanocoap_cache,$(USEMODULE)))
   USEMODULE += hashes
 endif
 
+ifneq (,$(filter nanocoap_vfs,$(USEMODULE)))
+  USEMODULE += nanocoap_sock
+  USEMODULE += vfs
+endif
+
 ifneq (,$(filter nanocoap_%,$(USEMODULE)))
   USEMODULE += nanocoap
 endif

sys/include/net/nanocoap_vfs.h

@@ -0,0 +1,58 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+/**
+ * @ingroup     net_nanosock
+ * @brief       VFS NanoCoAP helper functions
+ *
+ * @{
+ *
+ * @file
+ * @brief       VFS NanoCoAP helper functions
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ */
+#ifndef NET_NANOCOAP_VFS_H
+#define NET_NANOCOAP_VFS_H
+
+#include "net/nanocoap_sock.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief   Downloads the resource behind @p url via blockwise
+ *          GET and stores it in the file @p dst.
+ *
+ * @param[in]   url     URL to the resource
+ * @param[in]   dst     Path to the destination file
+ *
+ * @returns     0 on success
+ * @returns     <0 on error
+ */
+int nanocoap_vfs_get_url(const char *url, const char *dst);
+
+/**
+ * @brief   Downloads the resource behind @p path via blockwise
+ *          GET and stores it in the file @p dst.
+ *
+ * @param[in]   sock    Connection to the server
+ * @param[in]   path    Remote query path to the resource
+ * @param[in]   dst     Local path to the destination file
+ *
+ * @returns     0 on success
+ * @returns     <0 on error
+ */
+int nanocoap_vfs_get(nanocoap_sock_t *sock, const char *path, const char *dst);
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* NET_NANOCOAP_VFS_H */
+/** @} */

sys/net/application_layer/nanocoap/vfs.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2022 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.
+ */
+
+/**
+ * @ingroup     net_nanocoap
+ * @{
+ *
+ * @file
+ * @brief       Nanocoap VFS helpers
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ *
+ * @}
+ */
+
+#include <fcntl.h>
+#include "net/nanocoap_sock.h"
+#include "net/sock/util.h"
+#include "vfs.h"
+
+#define ENABLE_DEBUG 0
+#include "debug.h"
+
+static int _2file(void *arg, size_t offset, uint8_t *buf, size_t len, int more)
+{
+    (void)more;
+    int *fd = arg;
+
+    vfs_lseek(*fd, offset, SEEK_SET);
+    return vfs_write(*fd, buf, len);
+}
+
+static int _prepare_file(const char *dst, char *dst_tmp, size_t len)
+{
+    /* download to temp file, rename it later */
+    if (snprintf(dst_tmp, len, "%s.t", dst) > (int)len) {
+        return -ENOBUFS;
+    }
+
+    return vfs_open(dst_tmp, O_CREAT | O_WRONLY | O_TRUNC, 0644);
+}
+
+static int _finalize_file(int fd, int res, const char *dst, const char *dst_tmp)
+{
+    vfs_close(fd);
+
+    /* move file to it's final location */
+    if (res >= 0) {
+        DEBUG("nanocoap: moving %s to %s\n", dst_tmp, dst);
+        vfs_unlink(dst);
+        res = vfs_rename(dst_tmp, dst);
+    }
+
+    vfs_unlink(dst_tmp);
+
+    return res;
+}
+
+int nanocoap_vfs_get(nanocoap_sock_t *sock, const char *path, const char *dst)
+{
+    int fd, res;
+    char dst_tmp[CONFIG_SOCK_URLPATH_MAXLEN];
+
+    DEBUG("nanocoap: downloading %s to %s\n", path, dst_tmp);
+
+    fd = _prepare_file(dst, dst_tmp, sizeof(dst_tmp));
+    if (fd < 0) {
+        return fd;
+    }
+    res = nanocoap_sock_get_blockwise(sock, path, CONFIG_NANOCOAP_BLOCKSIZE_DEFAULT,
+                                      _2file, &fd);
+    return _finalize_file(fd, res, dst, dst_tmp);
+}
+
+int nanocoap_vfs_get_url(const char *url, const char *dst)
+{
+    int fd, res;
+    char dst_tmp[CONFIG_SOCK_URLPATH_MAXLEN];
+
+    DEBUG("nanocoap: downloading %s to %s\n", url, dst_tmp);
+
+    fd = _prepare_file(dst, dst_tmp, sizeof(dst_tmp));
+    if (fd < 0) {
+        return fd;
+    }
+    res = nanocoap_get_blockwise_url(url, CONFIG_NANOCOAP_BLOCKSIZE_DEFAULT,
+                                     _2file, &fd);
+    return _finalize_file(fd, res, dst, dst_tmp);
+}