libfstools: add rootdisk overlay volume support

Uses either ext4 or f2fs, depending on the overlay volume size

Signed-off-by: Felix Fietkau <nbd@nbd.name>

2 files changed, 284 insertions, 0 deletions

diff --git a/libfstools/rootdisk.c b/libfstools/rootdisk.c
new file mode 100644
index 0000000..98c749d
--- /dev/null
+++ b/libfstools/rootdisk.c
@@ -0,0 +1,283 @@
+/*
+ * Copyright (C) 2016 Felix Fietkau <nbd@nbd.name>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License version 2.1
+ * as published by the Free Software Foundation
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define F2FS_MINSIZE	(100 * 1024 * 1024)
+#define _FILE_OFFSET_BITS 64
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <sys/mount.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "libfstools.h"
+#include "volume.h"
+
+#include <linux/loop.h>
+
+#define ROOTDEV_OVERLAY_ALIGN	(64ULL * 1024ULL)
+
+struct squashfs_super_block {
+	uint32_t s_magic;
+	uint32_t pad0[9];
+	uint64_t bytes_used;
+};
+
+struct rootdev_volume {
+	struct volume v;
+	uint64_t offset;
+	char loop_name[32];
+};
+
+static const char *rootdev;
+static struct driver rootdisk_driver;
+
+static char *get_blockdev(dev_t dev)
+{
+	const char *dirname = "/dev";
+	DIR *dir = opendir(dirname);
+	struct dirent *d;
+	struct stat st;
+	static char buf[256];
+	char *ret = NULL;
+
+	if (!dir)
+		return ret;
+
+	while ((d = readdir(dir)) != NULL) {
+		snprintf(buf, sizeof(buf), "%s/%s", dirname, d->d_name);
+
+		if (lstat(buf, &st) != 0)
+			continue;
+
+		if (!S_ISBLK(st.st_mode))
+			continue;
+
+		if (st.st_rdev != dev)
+			continue;
+
+		ret = buf;
+		break;
+	}
+
+	closedir(dir);
+	return ret;
+}
+
+static char *get_rootdev(const char *dir)
+{
+	struct stat st;
+
+	if (stat(dir, &st))
+		return NULL;
+
+	return get_blockdev(S_ISBLK(st.st_mode) ? st.st_rdev : st.st_dev);
+}
+
+static int get_squashfs(struct squashfs_super_block *sb)
+{
+	FILE *f;
+	int len;
+
+	f = fopen(rootdev, "r");
+	if (!f)
+		return -1;
+
+	len = fread(sb, sizeof(*sb), 1, f);
+	fclose(f);
+
+	if (len != 1)
+		return -1;
+
+	return 0;
+}
+
+static bool rootdisk_use_f2fs(struct rootdev_volume *p)
+{
+	uint64_t size = 0;
+	bool ret = false;
+	int fd;
+
+	fd = open(rootdev, O_RDONLY);
+	if (ioctl(fd, BLKGETSIZE64, &size) == 0)
+		ret = size - p->offset > F2FS_MINSIZE;
+	close(fd);
+
+	return ret;
+}
+
+static struct volume *rootdisk_volume_find(char *name)
+{
+	struct squashfs_super_block sb;
+	struct rootdev_volume *p;
+
+	if (strcmp(name, "rootfs_data") != 0)
+		return NULL;
+
+	if (!rootdev)
+		rootdev = get_rootdev("/");
+	if (!rootdev)
+		rootdev = get_rootdev("/rom");
+	if (!rootdev)
+		return NULL;
+
+	if (strstr(rootdev, "mtdblock") ||
+	    strstr(rootdev, "ubiblock"))
+		return NULL;
+
+	if (get_squashfs(&sb))
+		return NULL;
+
+	if (memcmp(&sb.s_magic, "hsqs", sizeof(sb.s_magic)) != 0)
+		return NULL;
+
+	p = calloc(1, sizeof(*p));
+	p->v.drv = &rootdisk_driver;
+	p->v.name = "rootfs_data";
+
+	p->offset = le64_to_cpu(sb.bytes_used);
+	p->offset = ((p->offset + (ROOTDEV_OVERLAY_ALIGN - 1)) &
+		     ~(ROOTDEV_OVERLAY_ALIGN - 1));
+
+	return &p->v;
+}
+
+static int rootdisk_volume_identify(struct volume *v)
+{
+	struct rootdev_volume *p = container_of(v, struct rootdev_volume, v);
+	int ret = FS_NONE;
+	uint32_t magic = 0;
+	FILE *f;
+
+	f = fopen(rootdev, "r");
+	if (!f)
+		return ret;
+
+	fseeko(f, p->offset + 0x400, SEEK_SET);
+	fread(&magic, sizeof(magic), 1, f);
+
+	if (magic == cpu_to_le32(0xF2F52010))
+		ret = FS_F2FS;
+
+	magic = 0;
+	fseeko(f, p->offset + 0x438, SEEK_SET);
+	fread(&magic, sizeof(magic), 1, f);
+	if ((le32_to_cpu(magic) & 0xffff) == 0xef53)
+		ret = FS_EXT4;
+
+	fclose(f);
+
+	return ret;
+}
+
+static int rootdisk_create_loop(struct rootdev_volume *p)
+{
+	struct loop_info64 info;
+	int ret = -1;
+	int fd = -1;
+	int i, ffd;
+
+	ffd = open(rootdev, O_RDWR);
+	if (ffd < 0)
+		return -1;
+
+	for (i = 0; i < 8; i++) {
+		snprintf(p->loop_name, sizeof(p->loop_name), "/dev/loop%d",
+			 i);
+
+		if (fd >= 0)
+			close(fd);
+
+		fd = open(p->loop_name, O_RDWR);
+		if (fd < 0)
+			continue;
+
+		if (ioctl(fd, LOOP_GET_STATUS64, &info) == 0) {
+			if (strcmp((char *) info.lo_file_name, rootdev) != 0)
+				continue;
+			if (info.lo_offset != p->offset)
+				continue;
+			ret = 0;
+			break;
+		}
+
+		if (errno != ENXIO)
+			continue;
+
+		if (ioctl(fd, LOOP_SET_FD, ffd) != 0)
+			continue;
+
+		memset(&info, 0, sizeof(info));
+		snprintf((char *) info.lo_file_name, sizeof(info.lo_file_name), "%s",
+			 rootdev);
+		info.lo_offset = p->offset;
+
+		if (ioctl(fd, LOOP_SET_STATUS64, &info) != 0) {
+			ioctl(fd, LOOP_CLR_FD, 0);
+			continue;
+		}
+
+		ret = 0;
+		break;
+	}
+
+	if (fd >= 0)
+		close(fd);
+
+	close(ffd);
+
+	if (ret)
+		p->loop_name[0] = 0;
+
+	return ret;
+}
+
+static int rootdisk_volume_init(struct volume *v)
+{
+	struct rootdev_volume *p = container_of(v, struct rootdev_volume, v);
+	char str[128];
+
+	if (!p->loop_name[0] && rootdisk_create_loop(p) != 0)
+		return -1;
+
+	v->type = BLOCKDEV;
+	v->blk = p->loop_name;
+
+	switch (rootdisk_volume_identify(v)) {
+	case FS_NONE:
+		ULOG_INFO("rootdisk overlay filesystem has not been formatted yet\n");
+		if (rootdisk_use_f2fs(p))
+			snprintf(str, sizeof(str), "mkfs.f2fs -l rootfs_data %s", v->blk);
+		else
+			snprintf(str, sizeof(str), "mkfs.ext4 %s", v->blk);
+		system(str);
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static struct driver rootdisk_driver = {
+	.name = "rootdisk",
+	.find = rootdisk_volume_find,
+	.init = rootdisk_volume_init,
+	.identify = rootdisk_volume_identify,
+};
+
+DRIVER(rootdisk_driver);
diff --git a/libfstools/volume.h b/libfstools/volume.h
index fdd97d1..912b711 100644
--- a/libfstools/volume.h
+++ b/libfstools/volume.h
@@ -47,6 +47,7 @@ enum {
 	NANDFLASH,
 	NORFLASH,
 	UBIVOLUME,
+	BLOCKDEV,
 };
 
 struct volume {