pkg/tinyvcdiff: add VFS driver

pkg/tinyvcdiff/Kconfig

@@ -36,4 +36,11 @@ config TINYVCDIFF_MTD_WRITE_SIZE
 
 endif # MODULE_TINYVCDIFF_MTD
 
+config MODULE_TINYVCDIFF_VFS
+    bool "VFS Backend"
+    depends on MODULE_VFS
+    default y
+    help
+        Use a VFS file as VCDIFF target or source.
+
 endif # PACKAGE_TINYVCDIFF

pkg/tinyvcdiff/Makefile.dep

@@ -1,3 +1,7 @@
 ifneq (,$(filter mtd,$(USEMODULE)))
   USEMODULE += tinyvcdiff_mtd
 endif
+
+ifneq (,$(filter vfs,$(USEMODULE)))
+  USEMODULE += tinyvcdiff_vfs
+endif

pkg/tinyvcdiff/Makefile.include

@@ -13,3 +13,7 @@ INCLUDES += -I$(RIOTPKG)/tinyvcdiff/include
 ifneq (,$(filter tinyvcdiff_mtd,$(USEMODULE)))
   DIRS += $(RIOTPKG)/tinyvcdiff/contrib/tinyvcdiff_mtd
 endif
+
+ifneq (,$(filter tinyvcdiff_vfs,$(USEMODULE)))
+  DIRS += $(RIOTPKG)/tinyvcdiff/contrib/tinyvcdiff_vfs
+endif

pkg/tinyvcdiff/contrib/tinyvcdiff_vfs/Makefile

@@ -0,0 +1,3 @@
+MODULE = tinyvcdiff_vfs
+
+include $(RIOTBASE)/Makefile.base

pkg/tinyvcdiff/contrib/tinyvcdiff_vfs/vfs.c

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2022 Juergen Fitschen
+ *
+ * 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.
+ */
+
+#include "vcdiff_vfs.h"
+#include <unistd.h>
+#include "errno.h"
+
+static int _read (void *dev, uint8_t *dest, size_t offset, size_t len)
+{
+    int rc;
+    vcdiff_vfs_t *vfs = dev;
+
+    /* seek to the given offset */
+    rc = vfs_lseek(vfs->fd, offset, SEEK_SET);
+    if (rc < 0) {
+        return rc;
+    } else if ((size_t) rc != offset) {
+        return -EFAULT;
+    }
+
+    /* read from file into the buffer */
+    rc = vfs_read(vfs->fd, dest, len);
+    if (rc < 0) {
+        return rc;
+    } else if ((size_t) rc != len) {
+        return -EFAULT;
+    }
+
+    return 0;
+}
+
+static int _write (void *dev, uint8_t *src, size_t offset, size_t len)
+{
+    int rc;
+    vcdiff_vfs_t *vfs = dev;
+
+    /* make sure to stay in the set file size bounds */
+    if (offset + len > vfs->max_size) {
+        return -EFBIG;
+    }
+
+    /* seek to the given offset */
+    rc = vfs_lseek(vfs->fd, offset, SEEK_SET);
+    if (rc < 0) {
+        return rc;
+    } else if ((size_t) rc != offset) {
+        return -EFAULT;
+    }
+
+    /* write all bytes to the file */
+    rc = vfs_write(vfs->fd, src, len);
+    if (rc < 0) {
+        return rc;
+    } else if ((size_t) rc != len) {
+        return -EFAULT;
+    }
+
+    return 0;
+}
+
+const vcdiff_driver_t vcdiff_vfs_driver = {
+    .read = _read,
+    .write = _write
+};

pkg/tinyvcdiff/include/vcdiff_vfs.h

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2022 Juergen Fitschen
+ *
+ * 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.
+ */
+
+/**
+ * @{
+ *
+ * @file
+ * @ingroup  pkg_tinyvcdiff
+ *
+ * @author  Juergen Fitschen <me@jue.yt>
+ */
+
+#ifndef VCDIFF_VFS_H
+#define VCDIFF_VFS_H
+
+#include "vcdiff.h"
+#include "vfs.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @brief Driver for accessing VFS-based file access
+ */
+extern const vcdiff_driver_t vcdiff_vfs_driver;
+
+/**
+ * @brief Context for the underlying file
+ */
+typedef struct {
+    int fd;          /**< File descriptor of the VFS file */
+    size_t max_size; /**< Maxmimum file size for vcdiff target files */
+} vcdiff_vfs_t;
+
+/**
+ * @brief Initializes vcdiff_vfs_t with maximum allowed file size
+ */
+#define VCDIFF_VFS_INIT_MAX_SIZE(FD, SIZE) { .fd = FD, .max_size = SIZE }
+
+/**
+ * @brief Initializes vcdiff_vfs_t
+ */
+#define VCDIFF_VFS_INIT(FD) VCDIFF_VFS_INIT_MAX_SIZE(FD, SIZE_MAX)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* VCDIFF_VFS_H */
+/** @} */