sys/riotboot: add helper functions for riotboot VFS

sys/auto_init/auto_init.c

@@ -327,6 +327,11 @@ extern void auto_init_sock_dns(void);
 AUTO_INIT(auto_init_sock_dns,
           AUTO_INIT_PRIO_MOD_DOCK_DNS);
 #endif
+#if IS_USED(MODULE_RIOTBOOT_VFS) && !IS_USED(RIOTBOOT)
+extern void riotboot_vfs_cancel(void);
+AUTO_INIT(riotboot_vfs_cancel,
+          AUTO_INIT_PRIO_RIOTBOOT_VFS);
+#endif
 
 void auto_init(void)
 {

sys/auto_init/include/auto_init_priorities.h

@@ -354,6 +354,14 @@ extern "C" {
 #define AUTO_INIT_PRIO_MOD_DOCK_DNS                     1550
 #endif
 
+/**
+ * @brief   Remove RIOTBOOT canary after successful boot
+ *          This must always be the last step
+ */
+#ifndef AUTO_INIT_PRIO_RIOTBOOT_VFS
+#define AUTO_INIT_PRIO_RIOTBOOT_VFS                     9999
+#endif
+
 #ifdef __cplusplus
 }
 #endif

sys/include/riotboot/vfs.h

@@ -0,0 +1,91 @@
+/*
+ * 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_riotboot_vfs VFS Image loader
+ * @ingroup     sys
+ * @{
+ *
+ * @file
+ * @brief       riotboot as a VFS based bootloader
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ *
+ * @}
+ */
+
+#ifndef RIOTBOOT_VFS_H
+#define RIOTBOOT_VFS_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <string.h>
+
+#include "vfs_util.h"
+#include "vfs_default.h"
+
+/**
+ * @brief   File that contains the path to the new image
+ *
+ *          If this file is present, riotboot will attempt to load it
+ *          as the new firmware.
+ */
+#ifndef RIOTBOOT_VFS_UPDATE_FILE
+#define RIOTBOOT_VFS_UPDATE_FILE VFS_DEFAULT_DATA "/do_update"
+#endif
+
+/**
+ * @brief   File that contains the previous firmware
+ *
+ *          Riotboot will make a backup of the current firmware to
+ *          restore the old image if the new one fails to boot.
+ */
+#ifndef RIOTBOOT_VFS_BACKUP_FILE
+#define RIOTBOOT_VFS_BACKUP_FILE VFS_DEFAULT_DATA "/old_image.bin"
+#endif
+
+/**
+ * @brief   Mark the image behind @p file as the one that should be flashed
+ *          the next time riotboot runs.
+ *
+ *          This only creates the @ref RIOTBOOT_VFS_UPDATE_FILE, it will not perform a reboot.
+ *
+ * @param[in] file  Path to the firmware image
+ *
+ * @return 0 on success
+ *        <0 on error
+ */
+static inline int riotboot_vfs_schedule(const char *file)
+{
+    return vfs_file_from_buffer(RIOTBOOT_VFS_UPDATE_FILE, file, strlen(file));
+}
+
+/**
+ * @brief   Unschedule a pending firmware update
+ *
+ *          This removes the flag file created by @ref riotboot_vfs_schedule
+ */
+void riotboot_vfs_cancel(void);
+
+/**
+ * @brief   Dump the current firmware image to a file
+ *
+ * @param[in] file  Path where the firmware image should be written to
+ *
+ * @return 0 on success
+ *        <0 on error
+ */
+int riotboot_vfs_dump_rom(const char *file);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* RIOTBOOT_VFS_H */

sys/riotboot/vfs.c

@@ -0,0 +1,69 @@
+/*
+ * 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.
+ */
+
+/**
+ * @ingroup     sys_riotboot_vfs
+ * @{
+ *
+ * @file
+ * @brief       VFS Bootloader helpers
+ *
+ * @author      Benjamin Valentin <benjamin.valentin@ml-pa.com>
+ *
+ * @}
+ */
+
+#include <string.h>
+
+#include "architecture.h"
+#include "vfs_util.h"
+#include "periph/flashpage.h"
+#include "riotboot/vfs.h"
+
+/* try to guess the end of the firmware */
+static const void *_first_free_chunk(const void *start)
+{
+    const uword_t *cur = start;
+    const uword_t *end = flashpage_addr(FLASHPAGE_NUMOF);
+    uword_t empty;
+    unsigned const chunk_size = 256;
+    memset(&empty, FLASHPAGE_ERASE_STATE, sizeof(empty));
+
+    /* try to find the first unused page */
+    while (cur < end) {
+        if (cur[0] == empty && cur[1] == empty &&
+            cur[2] == empty && cur[3] == empty) {
+            break;
+        }
+        cur += chunk_size;
+    }
+
+    return cur;
+}
+
+int riotboot_vfs_dump_rom(const char *file)
+{
+    const void *start, *end;
+
+    if (IS_ACTIVE(RIOTBOOT)) {
+        start = (void *)(uintptr_t)SLOT0_OFFSET;
+        end   = _first_free_chunk(start);
+    } else {
+        start = (void *)cpu_get_image_baseaddr();
+        end   = flashpage_addr(flashpage_first_free());
+    }
+
+    return vfs_file_from_buffer(file, start, end - start);
+}
+
+void riotboot_vfs_cancel(void)
+{
+#ifdef MODULE_VFS
+    vfs_unlink(RIOTBOOT_VFS_UPDATE_FILE);
+#endif
+}