/* sfs.c - Amiga Smart FileSystem.  */
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 2005,2006,2007,2008,2009  Free Software Foundation, Inc.
 *
 *  GRUB is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *(at your option) any later version.
 *
 *  GRUB 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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with GRUB.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <grub/err.h>
#include <grub/file.h>
#include <grub/mm.h>
#include <grub/misc.h>
#include <grub/disk.h>
#include <grub/types.h>
#include <grub/fshelp.h>
#include <r_types.h>
/* The common header for a block.  */
R_PACKED(
	struct grub_sfs_bheader {
		grub_uint8_t magic[4];
		grub_uint32_t chksum;
		grub_uint32_t ipointtomyself;
	});

/* The sfs rootblock.  */
R_PACKED(
	struct grub_sfs_rblock {
		struct grub_sfs_bheader header;
		grub_uint32_t version;
		grub_uint8_t unused1[36];
		grub_uint32_t blocksize;
		grub_uint8_t unused2[40];
		grub_uint8_t unused3[8];
		grub_uint32_t rootobject;
		grub_uint32_t btree;
	});

/* A SFS object container.  */
R_PACKED(
	struct grub_sfs_obj {
		grub_uint8_t unused1[4];
		grub_uint32_t nodeid;
		grub_uint8_t unused2[4];
		union {
			R_PACKED (
				struct
				{
					grub_uint32_t first_block;
					grub_uint32_t size;
				})
			file;
			R_PACKED (
				struct
				{
					grub_uint32_t hashtable;
					grub_uint32_t dir_objc;
				})
			dir;
		} file_dir;
		grub_uint8_t unused3[4];
		grub_uint8_t type;
		grub_uint8_t filename[1];
		grub_uint8_t comment[1];
	});

#define GRUB_SFS_TYPE_DELETED 32
#define GRUB_SFS_TYPE_SYMLINK 64
#define GRUB_SFS_TYPE_DIR 128

/* A SFS object container.  */
R_PACKED(
	struct grub_sfs_objc {
		struct grub_sfs_bheader header;
		grub_uint32_t parent;
		grub_uint32_t next;
		grub_uint32_t prev;
		/* The amount of objects depends on the blocksize.  */
		struct grub_sfs_obj objects[1];
	});

R_PACKED(
	struct grub_sfs_btree_node {
		grub_uint32_t key;
		grub_uint32_t data;
	});

R_PACKED(
	struct grub_sfs_btree_extent {
		grub_uint32_t key;
		grub_uint32_t next;
		grub_uint32_t prev;
		grub_uint16_t size;
	});

R_PACKED(
	struct grub_sfs_btree {
		struct grub_sfs_bheader header;
		grub_uint16_t nodes;
		grub_uint8_t leaf;
		grub_uint8_t nodesize;
		/* Normally this can be kind of node, but just extents are
		supported.  */
		struct grub_sfs_btree_node node[1];
	});

struct grub_fshelp_node {
	struct grub_sfs_data *data;
	int block;
	int size;
};

/* Information about a "mounted" sfs filesystem.  */
struct grub_sfs_data {
	struct grub_sfs_rblock rblock;
	struct grub_fshelp_node diropen;
	grub_disk_t disk;

	/* Blocksize in sectors.  */
	unsigned int blocksize;

	/* Label of the filesystem.  */
	char *label;
};

/* Lookup the extent starting with BLOCK in the filesystem described
by DATA.  Return the extent size in SIZE and the following extent
in NEXTEXT.  */
static grub_err_t
grub_sfs_read_extent(struct grub_sfs_data *data, unsigned int block, int *size, int *nextext) {
	char *treeblock;
	struct grub_sfs_btree *tree;
	int i;
	int next;

	if (!block) {
		return 0;
	}

	treeblock = grub_malloc (data->blocksize);
	if (!treeblock) {
		return grub_error (GRUB_ERR_OUT_OF_MEMORY, "Failed to allocate memory for treeblock");
	}

	next = grub_be_to_cpu32 (data->rblock.btree);
	tree = (struct grub_sfs_btree *)treeblock;

	/* Handle this level in the btree.  */
	do {
		grub_disk_read (data->disk, next, 0, data->blocksize, treeblock);
		if (grub_errno) {
			grub_free (treeblock);
			return grub_errno;
		}

		for (i = grub_be_to_cpu16 (tree->nodes) - 1; i >= 0; i--) {

#define EXTNODE(tree, index) \
	((struct grub_sfs_btree_node *) (((char *)&(tree)->node[0]) + (index) *(tree)->nodesize))

			/* Follow the tree down to the leaf level.  */
			if ((grub_be_to_cpu32 (EXTNODE (tree, i)->key) <= block) && !tree->leaf) {
				next = grub_be_to_cpu32 (EXTNODE (tree, i)->data);
				break;
			}

			/* If the leaf level is reached, just find the correct extent.  */
			if (grub_be_to_cpu32 (EXTNODE (tree, i)->key) == block && tree->leaf) {
				struct grub_sfs_btree_extent *extent;
				extent = (struct grub_sfs_btree_extent *)EXTNODE (tree, i);

				/* We found a correct leaf.  */
				*size = grub_be_to_cpu16 (extent->size);
				*nextext = grub_be_to_cpu32 (extent->next);

				grub_free (treeblock);
				return 0;
			}

#undef EXTNODE
		}
	} while (!tree->leaf);

	grub_free (treeblock);

	return grub_error (GRUB_ERR_FILE_READ_ERROR, "SFS extent not found");
}

static grub_disk_addr_t
grub_sfs_read_block(grub_fshelp_node_t node, grub_disk_addr_t fileblock) {
	int blk = node->block;
	int size = 0;
	int next = 0;

	while (blk) {
		grub_err_t err;

		/* In case of the first block we don't have to lookup the
		extent, the minimum size is always 1.  */
		if (fileblock == 0) {
			return blk;
		}

		err = grub_sfs_read_extent (node->data, blk, &size, &next);
		if (err) {
			return 0;
		}

		if (fileblock < (unsigned int)size) {
			return fileblock + blk;
		}

		fileblock -= size;

		blk = next;
	}

	grub_error (GRUB_ERR_FILE_READ_ERROR,
		"reading a SFS block outside the extent");

	return 0;
}

/* Read LEN bytes from the file described by DATA starting with byte
POS.  Return the amount of read bytes in READ.  */
static grub_ssize_t
grub_sfs_read_file(grub_fshelp_node_t node,
	void (*read_hook) (grub_disk_addr_t sector,
		unsigned offset,
		unsigned length,
		void *closure),
	void *closure,
	int flags,
	int pos,
	grub_size_t len,
	char *buf) {
	return grub_fshelp_read_file (node->data->disk, node, read_hook, closure, flags, pos, len, buf, grub_sfs_read_block, node->size, 0);
}

static struct grub_sfs_data *
grub_sfs_mount(grub_disk_t disk) {
	struct grub_sfs_data *data;
	struct grub_sfs_objc *rootobjc;
	char *rootobjc_data = 0;
	unsigned int blk;

	data = grub_malloc (sizeof (*data));
	if (!data) {
		return 0;
	}

	/* Read the rootblock.  */
	grub_disk_read (disk, 0, 0, sizeof (struct grub_sfs_rblock), &data->rblock);
	if (grub_errno) {
		goto fail;
	}

	/* Make sure this is a sfs filesystem.  */
	if (strncmp ((char *) (data->rblock.header.magic), "SFS", 4)) {
		grub_error (GRUB_ERR_BAD_FS, "not a SFS filesystem");
		goto fail;
	}

	data->blocksize = grub_be_to_cpu32 (data->rblock.blocksize);
	rootobjc_data = grub_malloc (data->blocksize);
	if (!rootobjc_data) {
		goto fail;
	}

	/* Read the root object container.  */
	grub_disk_read (disk, grub_be_to_cpu32 (data->rblock.rootobject), 0, data->blocksize, rootobjc_data);
	if (grub_errno) {
		goto fail;
	}

	rootobjc = (struct grub_sfs_objc *)rootobjc_data;

	blk = grub_be_to_cpu32 (rootobjc->objects[0].file_dir.dir.dir_objc);
	data->diropen.size = 0;
	data->diropen.block = blk;
	data->diropen.data = data;
	data->disk = disk;
	data->label = grub_strdup ((char *) (rootobjc->objects[0].filename));

	return data;

fail:
	if (grub_errno == GRUB_ERR_OUT_OF_RANGE) {
		grub_error (GRUB_ERR_BAD_FS, "not an SFS filesystem");
	}

	grub_free (data);
	grub_free (rootobjc_data);
	return 0;
}

static char *
grub_sfs_read_symlink(grub_fshelp_node_t node) {
	struct grub_sfs_data *data = node->data;
	char *symlink;
	char *block;

	block = grub_malloc (data->blocksize);
	if (!block) {
		return 0;
	}

	grub_disk_read (data->disk, node->block, 0, data->blocksize, block);
	if (grub_errno) {
		grub_free (block);
		return 0;
	}

	/* This is just a wild guess, but it always worked for me.  How the
	SLNK block looks like is not documented in the SFS docs.  */
	symlink = grub_strdup (&block[24]);
	grub_free (block);
	if (!symlink) {
		return 0;
	}

	return symlink;
}

static int
grub_sfs_create_node(const char *name, int block, int size, int type, struct grub_sfs_data *data, int(*hook)(const char *filename, enum grub_fshelp_filetype filetype, grub_fshelp_node_t node, void *closure), void *closure) {
	struct grub_fshelp_node *node;

	node = grub_malloc (sizeof (*node));
	if (!node) {
		return 1;
	}

	node->data = data;
	node->size = size;
	node->block = block;

	return hook (name, type, node, closure);
}

static int
grub_sfs_iterate_dir(grub_fshelp_node_t dir,
	int (*hook) (const char *filename,
		enum grub_fshelp_filetype filetype,
		grub_fshelp_node_t node,
		void *closure),
	void *closure) {
	struct grub_sfs_data *data = dir->data;
	char *objc_data;
	struct grub_sfs_objc *objc;
	unsigned int next = dir->block;
	int pos;

	objc_data = grub_malloc (data->blocksize);
	if (!objc_data) {
		goto fail;
	}

	/* The Object container can consist of multiple blocks, iterate over
	every block.  */
	while (next) {
		grub_disk_read (data->disk, next, 0, data->blocksize, objc_data);
		if (grub_errno) {
			goto fail;
		}

		objc = (struct grub_sfs_objc *)objc_data;

		pos = (char *)&objc->objects[0] - (char *)objc;

		/* Iterate over all entries in this block.  */
		while (pos + sizeof (struct grub_sfs_obj) < data->blocksize) {
			struct grub_sfs_obj *obj;
			obj = (struct grub_sfs_obj *) ((char *)objc + pos);
			char *filename = (char *) (obj->filename);
			int len;
			enum grub_fshelp_filetype type;
			unsigned int block;

			/* The filename and comment dynamically increase the size of
			the object.  */
			len = grub_strlen (filename);
			len += grub_strlen (filename + len + 1);

			pos += sizeof (*obj) + len;
			/* Round up to a multiple of two bytes.  */
			pos = ((pos + 1) >> 1) << 1;

			if (grub_strlen (filename) == 0) {
				continue;
			}

			/* First check if the file was not deleted.  */
			if (obj->type & GRUB_SFS_TYPE_DELETED) {
				continue;
			} else if (obj->type & GRUB_SFS_TYPE_SYMLINK) {
				type = GRUB_FSHELP_SYMLINK;
			} else if (obj->type & GRUB_SFS_TYPE_DIR) {
				type = GRUB_FSHELP_DIR;
			} else {
				type = GRUB_FSHELP_REG;
			}

			if (type == GRUB_FSHELP_DIR) {
				block = grub_be_to_cpu32 (obj->file_dir.dir.dir_objc);
			} else {
				block = grub_be_to_cpu32 (obj->file_dir.file.first_block);
			}

			if (grub_sfs_create_node (filename, block, grub_be_to_cpu32 (obj->file_dir.file.size), type, data, hook, closure)) {
				grub_free (objc_data);
				return 1;
			}
		}

		next = grub_be_to_cpu32 (objc->next);
	}

fail:
	grub_free (objc_data);
	return 0;
}

/* Open a file named NAME and initialize FILE.  */
static grub_err_t
grub_sfs_open(struct grub_file *file, const char *name) {
	struct grub_sfs_data *data;
	struct grub_fshelp_node *fdiro = 0;

	data = grub_sfs_mount (file->device->disk);
	if (!data) {
		goto fail;
	}

	grub_fshelp_find_file (name, &data->diropen, &fdiro, grub_sfs_iterate_dir, 0, grub_sfs_read_symlink, GRUB_FSHELP_REG);
	if (grub_errno) {
		goto fail;
	}

	file->size = fdiro->size;
	data->diropen = *fdiro;
	grub_free (fdiro);

	file->data = data;
	file->offset = 0;

	return 0;

fail:
	if (data && fdiro != &data->diropen) {
		grub_free (fdiro);
	}
	if (data) {
		grub_free (data->label);
	}
	grub_free (data);

	return grub_errno;
}

static grub_err_t
grub_sfs_close(grub_file_t file) {
	grub_free (file->data);

	return GRUB_ERR_NONE;
}

/* Read LEN bytes data from FILE into BUF.  */
static grub_ssize_t
grub_sfs_read(grub_file_t file, char *buf, grub_size_t len) {
	struct grub_sfs_data *data = (struct grub_sfs_data *)file->data;

	int size = grub_sfs_read_file (&data->diropen, file->read_hook, file->closure, file->flags, file->offset, len, buf);

	return size;
}

struct grub_sfs_dir_closure {
	int (*hook) (const char *filename,
		const struct grub_dirhook_info *info,
		void *closure);
	void *closure;
};

static int
iterate(const char *filename,
	enum grub_fshelp_filetype filetype,
	grub_fshelp_node_t node,
	void *closure) {
	struct grub_sfs_dir_closure *c = closure;
	struct grub_dirhook_info info;
	grub_memset (&info, 0, sizeof (info));
	info.dir = ((filetype & GRUB_FSHELP_TYPE_MASK) == GRUB_FSHELP_DIR);
	grub_free (node);
	return c->hook? c->hook (filename, &info, c->closure): 0;
}

static grub_err_t
grub_sfs_dir(grub_device_t device, const char *path, int(*hook)(const char *filename, const struct grub_dirhook_info *info, void *closure), void *closure) {
	struct grub_sfs_data *data = 0;
	struct grub_fshelp_node *fdiro = 0;
	struct grub_sfs_dir_closure c;

	data = grub_sfs_mount (device->disk);
	if (!data) {
		goto fail;
	}

	grub_fshelp_find_file (path, &data->diropen, &fdiro, grub_sfs_iterate_dir, 0, grub_sfs_read_symlink, GRUB_FSHELP_DIR);
	if (grub_errno) {
		goto fail;
	}

	c.hook = hook;
	c.closure = closure;
	grub_sfs_iterate_dir (fdiro, iterate, &c);

fail:
	if (data && fdiro != &data->diropen) {
		grub_free (fdiro);
	}
	if (data) {
		grub_free (data->label);
	}
	grub_free (data);

	return grub_errno;
}

static grub_err_t
grub_sfs_label(grub_device_t device, char **label) {
	struct grub_sfs_data *data;
	grub_disk_t disk = device->disk;

	data = grub_sfs_mount (disk);
	if (data) {
		*label = data->label;
	}

	grub_free (data);

	return grub_errno;
}

struct grub_fs grub_sfs_fs = {
	.name = "sfs",
	.dir = grub_sfs_dir,
	.open = grub_sfs_open,
	.read = grub_sfs_read,
	.close = grub_sfs_close,
	.label = grub_sfs_label,
	.next = 0
};
