fs/squashfs: new filesystem
authorJoao Marcos Costa <joaomarcos.costa@bootlin.com>
Thu, 30 Jul 2020 13:33:47 +0000 (15:33 +0200)
committerTom Rini <trini@konsulko.com>
Sat, 8 Aug 2020 02:31:32 +0000 (22:31 -0400)
Add support for SquashFS filesystem. Right now, it does not support
compression but support for zlib will be added in a follow-up commit.

Signed-off-by: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
16 files changed:
MAINTAINERS
common/spl/Kconfig
fs/Kconfig
fs/Makefile
fs/fs.c
fs/squashfs/Kconfig [new file with mode: 0644]
fs/squashfs/Makefile [new file with mode: 0644]
fs/squashfs/sqfs.c [new file with mode: 0644]
fs/squashfs/sqfs_decompressor.c [new file with mode: 0644]
fs/squashfs/sqfs_decompressor.h [new file with mode: 0644]
fs/squashfs/sqfs_dir.c [new file with mode: 0644]
fs/squashfs/sqfs_filesystem.h [new file with mode: 0644]
fs/squashfs/sqfs_inode.c [new file with mode: 0644]
fs/squashfs/sqfs_utils.h [new file with mode: 0644]
include/fs.h
include/squashfs.h [new file with mode: 0644]

index 889a73f..c2501e8 100644 (file)
@@ -969,6 +969,12 @@ S: Maintained
 F:     drivers/spmi/
 F:     include/spmi/
 
+SQUASHFS
+M:     Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+S:     Maintained
+F:     fs/squashfs/
+F:     include/sqfs.h
+
 TARGET_BCMNS3
 M:     Bharat Gooty <bharat.gooty@broadcom.com>
 M:     Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
index 10605f1..af8255a 100644 (file)
@@ -577,6 +577,15 @@ config SPL_FS_EXT4
          filesystem from within SPL. Support for the underlying block
          device (e.g. MMC or USB) must be enabled separately.
 
+config SPL_FS_SQUASHFS
+       bool "Support SquashFS filesystems"
+       select FS_SQUASHFS
+       help
+         Enable support for SquashFS filesystems with SPL. This permits
+         U-Boot (or Linux in Falcon mode) to be loaded from a SquashFS
+         filesystem from within SPL. Support for the underlying block
+         device (e.g. MMC or USB) must be enabled separately.
+
 config SPL_FS_FAT
        bool "Support FAT filesystems"
        select FS_FAT
index 1cb9831..620af7f 100644 (file)
@@ -22,4 +22,6 @@ source "fs/cramfs/Kconfig"
 
 source "fs/yaffs2/Kconfig"
 
+source "fs/squashfs/Kconfig"
+
 endmenu
index 42e669c..937cbcf 100644 (file)
@@ -9,6 +9,7 @@ obj-$(CONFIG_FS_LOADER) += fs.o
 obj-$(CONFIG_SPL_FS_FAT) += fat/
 obj-$(CONFIG_SPL_FS_EXT4) += ext4/
 obj-$(CONFIG_SPL_FS_CBFS) += cbfs/
+obj-$(CONFIG_SPL_FS_SQUASHFS) += squashfs/
 else
 obj-y                          += fs.o
 
@@ -23,5 +24,6 @@ obj-$(CONFIG_SANDBOX) += sandbox/
 obj-$(CONFIG_CMD_UBIFS) += ubifs/
 obj-$(CONFIG_YAFFS2) += yaffs2/
 obj-$(CONFIG_CMD_ZFS) += zfs/
+obj-$(CONFIG_FS_SQUASHFS) += squashfs/
 endif
 obj-y += fs_internal.o
diff --git a/fs/fs.c b/fs/fs.c
index edd8adc..5b31a36 100644 (file)
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -22,6 +22,7 @@
 #include <div64.h>
 #include <linux/math64.h>
 #include <efi_loader.h>
+#include <squashfs.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -276,6 +277,20 @@ static struct fstype_info fstypes[] = {
                .mkdir = fs_mkdir_unsupported,
                .ln = fs_ln_unsupported,
        },
+#endif
+#if IS_ENABLED(CONFIG_FS_SQUASHFS)
+       {
+               .fstype = FS_TYPE_SQUASHFS,
+               .name = "squashfs",
+               .probe = sqfs_probe,
+               .opendir = sqfs_opendir,
+               .readdir = sqfs_readdir,
+               .ls = fs_ls_generic,
+               .read = sqfs_read,
+               .size = sqfs_size,
+               .close = sqfs_close,
+               .closedir = sqfs_closedir,
+       },
 #endif
        {
                .fstype = FS_TYPE_ANY,
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
new file mode 100644 (file)
index 0000000..b9772e5
--- /dev/null
@@ -0,0 +1,10 @@
+config FS_SQUASHFS
+       bool "Enable SquashFS filesystem support"
+       help
+         This provides support for reading images from SquashFS filesystem.
+         Squashfs is a compressed read-only filesystem for Linux.
+         It uses zlib, lz4, lzo, or xz compression to compress files, inodes
+         and directories. Squashfs is intended for general read-only
+         filesystem use, for archival use (i.e. in cases where a .tar.gz file
+         may be used), and in constrained block device/memory systems (e.g.
+         embedded systems) where low overhead is needed.
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
new file mode 100644 (file)
index 0000000..ba66ee8
--- /dev/null
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+
+obj-$(CONFIG_$(SPL_)FS_SQUASHFS) = sqfs.o \
+                               sqfs_inode.o \
+                               sqfs_dir.o \
+                               sqfs_decompressor.o
diff --git a/fs/squashfs/sqfs.c b/fs/squashfs/sqfs.c
new file mode 100644 (file)
index 0000000..340e5eb
--- /dev/null
@@ -0,0 +1,1538 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ *
+ * sqfs.c: SquashFS filesystem implementation
+ */
+
+#include <asm/unaligned.h>
+#include <errno.h>
+#include <fs.h>
+#include <linux/types.h>
+#include <linux/byteorder/little_endian.h>
+#include <linux/byteorder/generic.h>
+#include <memalign.h>
+#include <stdlib.h>
+#include <string.h>
+#include <squashfs.h>
+#include <part.h>
+
+#include "sqfs_decompressor.h"
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+struct squashfs_ctxt {
+       struct disk_partition cur_part_info;
+       struct blk_desc *cur_dev;
+       struct squashfs_super_block *sblk;
+};
+
+static struct squashfs_ctxt ctxt;
+
+static int sqfs_disk_read(__u32 block, __u32 nr_blocks, void *buf)
+{
+       ulong ret;
+
+       if (!ctxt.cur_dev)
+               return -1;
+
+       ret = blk_dread(ctxt.cur_dev, ctxt.cur_part_info.start + block,
+                       nr_blocks, buf);
+
+       if (ret != nr_blocks)
+               return -1;
+
+       return ret;
+}
+
+static int sqfs_read_sblk(struct squashfs_super_block **sblk)
+{
+       *sblk = malloc_cache_aligned(ctxt.cur_dev->blksz);
+       if (!*sblk)
+               return -ENOMEM;
+
+       if (sqfs_disk_read(0, 1, *sblk) != 1) {
+               free(*sblk);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static int sqfs_count_tokens(const char *filename)
+{
+       int token_count = 1, l;
+
+       for (l = 1; l < strlen(filename); l++) {
+               if (filename[l] == '/')
+                       token_count++;
+       }
+
+       /* Ignore trailing '/' in path */
+       if (filename[strlen(filename) - 1] == '/')
+               token_count--;
+
+       if (!token_count)
+               token_count = 1;
+
+       return token_count;
+}
+
+/*
+ * Calculates how many blocks are needed for the buffer used in sqfs_disk_read.
+ * The memory section (e.g. inode table) start offset and its end (i.e. the next
+ * table start) must be specified. It also calculates the offset from which to
+ * start reading the buffer.
+ */
+static int sqfs_calc_n_blks(__le64 start, __le64 end, u64 *offset)
+{
+       u64 start_, table_size;
+
+       table_size = le64_to_cpu(end) - le64_to_cpu(start);
+       start_ = le64_to_cpu(start) / ctxt.cur_dev->blksz;
+       *offset = le64_to_cpu(start) - (start_ * ctxt.cur_dev->blksz);
+
+       return DIV_ROUND_UP(table_size + *offset, ctxt.cur_dev->blksz);
+}
+
+/*
+ * Retrieves fragment block entry and returns true if the fragment block is
+ * compressed
+ */
+static int sqfs_frag_lookup(u32 inode_fragment_index,
+                           struct squashfs_fragment_block_entry *e)
+{
+       u64 start, n_blks, src_len, table_offset, start_block;
+       unsigned char *metadata_buffer, *metadata, *table;
+       struct squashfs_fragment_block_entry *entries;
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       unsigned long dest_len;
+       int block, offset, ret;
+       u16 header, comp_type;
+
+       comp_type = get_unaligned_le16(&sblk->compression);
+
+       if (inode_fragment_index >= get_unaligned_le32(&sblk->fragments))
+               return -EINVAL;
+
+       start = get_unaligned_le64(&sblk->fragment_table_start) /
+               ctxt.cur_dev->blksz;
+       n_blks = sqfs_calc_n_blks(sblk->fragment_table_start,
+                                 sblk->export_table_start,
+                                 &table_offset);
+
+       /* Allocate a proper sized buffer to store the fragment index table */
+       table = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+       if (!table)
+               return -ENOMEM;
+
+       if (sqfs_disk_read(start, n_blks, table) < 0) {
+               free(table);
+               return -EINVAL;
+       }
+
+       block = SQFS_FRAGMENT_INDEX(inode_fragment_index);
+       offset = SQFS_FRAGMENT_INDEX_OFFSET(inode_fragment_index);
+
+       /*
+        * Get the start offset of the metadata block that contains the right
+        * fragment block entry
+        */
+       start_block = get_unaligned_le64(table + table_offset + block *
+                                        sizeof(u64));
+
+       start = start_block / ctxt.cur_dev->blksz;
+       n_blks = sqfs_calc_n_blks(cpu_to_le64(start_block),
+                                 sblk->fragment_table_start, &table_offset);
+
+       metadata_buffer = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+       if (!metadata_buffer) {
+               ret = -ENOMEM;
+               goto free_table;
+       }
+
+       if (sqfs_disk_read(start, n_blks, metadata_buffer) < 0) {
+               ret = -EINVAL;
+               goto free_buffer;
+       }
+
+       /* Every metadata block starts with a 16-bit header */
+       header = get_unaligned_le16(metadata_buffer + table_offset);
+       metadata = metadata_buffer + table_offset + SQFS_HEADER_SIZE;
+
+       entries = malloc(SQFS_METADATA_BLOCK_SIZE);
+       if (!entries) {
+               ret = -ENOMEM;
+               goto free_buffer;
+       }
+
+       if (SQFS_COMPRESSED_METADATA(header)) {
+               src_len = SQFS_METADATA_SIZE(header);
+               dest_len = SQFS_METADATA_BLOCK_SIZE;
+               ret = sqfs_decompress(comp_type, entries, &dest_len, metadata,
+                                     src_len);
+               if (ret) {
+                       ret = -EINVAL;
+                       goto free_entries;
+               }
+       } else {
+               memcpy(entries, metadata, SQFS_METADATA_SIZE(header));
+       }
+
+       *e = entries[offset];
+       ret = SQFS_COMPRESSED_BLOCK(e->size);
+
+free_entries:
+       free(entries);
+free_buffer:
+       free(metadata_buffer);
+free_table:
+       free(table);
+
+       return ret;
+}
+
+/*
+ * The entry name is a flexible array member, and we don't know its size before
+ * actually reading the entry. So we need a first copy to retrieve this size so
+ * we can finally copy the whole struct.
+ */
+static int sqfs_read_entry(struct squashfs_directory_entry **dest, void *src)
+{
+       struct squashfs_directory_entry *tmp;
+       u16 sz;
+
+       tmp = src;
+       sz = get_unaligned_le16(src + sizeof(*tmp) - sizeof(u16));
+       /*
+        * 'src' points to the begin of a directory entry, and 'sz' gets its
+        * 'name_size' member's value. name_size is actually the string
+        * length - 1, so adding 2 compensates this difference and adds space
+        * for the trailling null byte.
+        */
+       *dest = malloc(sizeof(*tmp) + sz + 2);
+       if (!*dest)
+               return -ENOMEM;
+
+       memcpy(*dest, src, sizeof(*tmp) + sz + 1);
+       (*dest)->name[sz + 1] = '\0';
+
+       return 0;
+}
+
+static int sqfs_get_tokens_length(char **tokens, int count)
+{
+       int length = 0, i;
+
+       /*
+        * 1 is added to the result of strlen to consider the slash separator
+        * between the tokens.
+        */
+       for (i = 0; i < count; i++)
+               length += strlen(tokens[i]) + 1;
+
+       return length;
+}
+
+/* Takes a token list and returns a single string with '/' as separator. */
+static char *sqfs_concat_tokens(char **token_list, int token_count)
+{
+       char *result;
+       int i, length = 0, offset = 0;
+
+       length = sqfs_get_tokens_length(token_list, token_count);
+
+       result = malloc(length + 1);
+       result[length] = '\0';
+
+       for (i = 0; i < token_count; i++) {
+               strcpy(result + offset, token_list[i]);
+               offset += strlen(token_list[i]);
+               result[offset++] = '/';
+       }
+
+       return result;
+}
+
+/*
+ * Differently from sqfs_concat_tokens, sqfs_join writes the result into a
+ * previously allocated string, and returns the number of bytes written.
+ */
+static int sqfs_join(char **strings, char *dest, int start, int end,
+                    char separator)
+{
+       int i, offset = 0;
+
+       for (i = start; i < end; i++) {
+               strcpy(dest + offset, strings[i]);
+               offset += strlen(strings[i]);
+               if (i < end - 1)
+                       dest[offset++] = separator;
+       }
+
+       return offset;
+}
+
+/*
+ * Fills the given token list using its size (count) and a source string (str)
+ */
+static int sqfs_tokenize(char **tokens, int count, const char *str)
+{
+       char *aux, *strc;
+       int i, j;
+
+       strc = strdup(str);
+       if (!strc)
+               return -ENOMEM;
+
+       if (!strcmp(strc, "/")) {
+               tokens[0] = strdup(strc);
+               if (!tokens[0]) {
+                       free(strc);
+                       return -ENOMEM;
+               }
+       } else {
+               for (j = 0; j < count; j++) {
+                       aux = strtok(!j ? strc : NULL, "/");
+                       tokens[j] = strdup(aux);
+                       if (!tokens[j]) {
+                               for (i = 0; i < j; i++)
+                                       free(tokens[i]);
+                               free(strc);
+                               return -ENOMEM;
+                       }
+               }
+       }
+
+       free(strc);
+
+       return 0;
+}
+
+/*
+ * Remove last 'updir + 1' tokens from the base path tokens list. This leaves us
+ * with a token list containing only the tokens needed to form the resolved
+ * path, and returns the decremented size of the token list.
+ */
+static int sqfs_clean_base_path(char **base, int count, int updir)
+{
+       int i;
+
+       for (i = count - updir - 1; i < count; i++)
+               free(base[i]);
+
+       return count - updir - 1;
+}
+
+/*
+ * Given the base ("current dir.") path and the relative one, generate the
+ * absolute path.
+ */
+static char *sqfs_get_abs_path(const char *base, const char *rel)
+{
+       char **base_tokens, **rel_tokens, *resolved = NULL;
+       int ret, bc, rc, i, updir = 0, resolved_size = 0, offset = 0;
+
+       /* Memory allocation for the token lists */
+       bc = sqfs_count_tokens(base);
+       rc = sqfs_count_tokens(rel);
+       if (bc < 1 || rc < 1)
+               return NULL;
+
+       base_tokens = malloc(bc * sizeof(char *));
+       if (!base_tokens)
+               return NULL;
+
+       rel_tokens = malloc(rc * sizeof(char *));
+       if (!rel_tokens)
+               goto free_b_tokens;
+
+       /* Fill token lists */
+       ret = sqfs_tokenize(base_tokens, bc, base);
+       if (ret)
+               goto free_r_tokens;
+
+       sqfs_tokenize(rel_tokens, rc, rel);
+       if (ret)
+               goto free_r_tokens;
+
+       /* count '..' occurrences in target path */
+       for (i = 0; i < rc; i++) {
+               if (!strcmp(rel_tokens[i], ".."))
+                       updir++;
+       }
+
+       /* Remove the last token and the '..' occurrences */
+       bc = sqfs_clean_base_path(base_tokens, bc, updir);
+       if (bc < 0)
+               goto free_r_tokens;
+
+       /* Calculate resolved path size */
+       if (!bc)
+               resolved_size++;
+
+       resolved_size += sqfs_get_tokens_length(base_tokens, bc) +
+               sqfs_get_tokens_length(rel_tokens, rc);
+
+       resolved = malloc(resolved_size + 1);
+       if (!resolved)
+               goto free_r_tokens_loop;
+
+       /* Set resolved path */
+       memset(resolved, '\0', resolved_size + 1);
+       offset += sqfs_join(base_tokens, resolved + offset, 0, bc, '/');
+       resolved[offset++] = '/';
+       offset += sqfs_join(rel_tokens, resolved + offset, updir, rc, '/');
+
+free_r_tokens_loop:
+       for (i = 0; i < rc; i++)
+               free(rel_tokens[i]);
+       for (i = 0; i < bc; i++)
+               free(base_tokens[i]);
+free_r_tokens:
+       free(rel_tokens);
+free_b_tokens:
+       free(base_tokens);
+
+       return resolved;
+}
+
+static char *sqfs_resolve_symlink(struct squashfs_symlink_inode *sym,
+                                 const char *base_path)
+{
+       char *resolved, *target;
+       u32 sz;
+
+       sz = get_unaligned_le32(&sym->symlink_size);
+       target = malloc(sz + 1);
+       if (!target)
+               return NULL;
+
+       /*
+        * There is no trailling null byte in the symlink's target path, so a
+        * copy is made and a '\0' is added at its end.
+        */
+       target[sz] = '\0';
+       /* Get target name (relative path) */
+       strncpy(target, sym->symlink, sz);
+
+       /* Relative -> absolute path conversion */
+       resolved = sqfs_get_abs_path(base_path, target);
+
+       free(target);
+
+       return resolved;
+}
+
+/*
+ * m_list contains each metadata block's position, and m_count is the number of
+ * elements of m_list. Those metadata blocks come from the compressed directory
+ * table.
+ */
+static int sqfs_search_dir(struct squashfs_dir_stream *dirs, char **token_list,
+                          int token_count, u32 *m_list, int m_count)
+{
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       char *path, *target, **sym_tokens, *res, *rem;
+       int j, ret, new_inode_number, offset;
+       struct squashfs_symlink_inode *sym;
+       struct squashfs_ldir_inode *ldir;
+       struct squashfs_dir_inode *dir;
+       struct fs_dir_stream *dirsp;
+       struct fs_dirent *dent;
+       unsigned char *table;
+
+       dirsp = (struct fs_dir_stream *)dirs;
+
+       /* Start by root inode */
+       table = sqfs_find_inode(dirs->inode_table, le32_to_cpu(sblk->inodes),
+                               sblk->inodes, sblk->block_size);
+
+       /* root is a regular directory, not an extended one */
+       dir = (struct squashfs_dir_inode *)table;
+
+       /* get directory offset in directory table */
+       offset = sqfs_dir_offset(table, m_list, m_count);
+       dirs->table = &dirs->dir_table[offset];
+
+       /* Setup directory header */
+       dirs->dir_header = malloc(SQFS_DIR_HEADER_SIZE);
+       if (!dirs->dir_header)
+               return -ENOMEM;
+
+       memcpy(dirs->dir_header, dirs->table, SQFS_DIR_HEADER_SIZE);
+
+       /* Initialize squashfs_dir_stream members */
+       dirs->table += SQFS_DIR_HEADER_SIZE;
+       dirs->size = get_unaligned_le16(&dir->file_size) - SQFS_DIR_HEADER_SIZE;
+       dirs->entry_count = dirs->dir_header->count + 1;
+
+       /* No path given -> root directory */
+       if (!strcmp(token_list[0], "/")) {
+               dirs->table = &dirs->dir_table[offset];
+               memcpy(&dirs->i_dir, dir, sizeof(*dir));
+               return 0;
+       }
+
+       for (j = 0; j < token_count; j++) {
+               if (!sqfs_is_dir(get_unaligned_le16(&dir->inode_type))) {
+                       printf("** Cannot find directory. **\n");
+                       return -EINVAL;
+               }
+
+               while (!sqfs_readdir(dirsp, &dent)) {
+                       ret = strcmp(dent->name, token_list[j]);
+                       if (!ret)
+                               break;
+                       free(dirs->entry);
+               }
+
+               if (ret) {
+                       printf("** Cannot find directory. **\n");
+                       return -EINVAL;
+               }
+
+               /* Redefine inode as the found token */
+               new_inode_number = dirs->entry->inode_offset +
+                       dirs->dir_header->inode_number;
+
+               /* Get reference to inode in the inode table */
+               table = sqfs_find_inode(dirs->inode_table, new_inode_number,
+                                       sblk->inodes, sblk->block_size);
+               dir = (struct squashfs_dir_inode *)table;
+
+               /* Check for symbolic link and inode type sanity */
+               if (get_unaligned_le16(&dir->inode_type) == SQFS_SYMLINK_TYPE) {
+                       sym = (struct squashfs_symlink_inode *)table;
+                       /* Get first j + 1 tokens */
+                       path = sqfs_concat_tokens(token_list, j + 1);
+                       /* Resolve for these tokens */
+                       target = sqfs_resolve_symlink(sym, path);
+                       /* Join remaining tokens */
+                       rem = sqfs_concat_tokens(token_list + j + 1, token_count -
+                                                j - 1);
+                       /* Concatenate remaining tokens and symlink's target */
+                       res = malloc(strlen(rem) + strlen(target) + 1);
+                       strcpy(res, target);
+                       res[strlen(target)] = '/';
+                       strcpy(res + strlen(target) + 1, rem);
+                       token_count = sqfs_count_tokens(res);
+
+                       if (token_count < 0)
+                               return -EINVAL;
+
+                       sym_tokens = malloc(token_count * sizeof(char *));
+                       if (!sym_tokens)
+                               return -EINVAL;
+
+                       /* Fill tokens list */
+                       ret = sqfs_tokenize(sym_tokens, token_count, res);
+                       if (ret)
+                               return -EINVAL;
+                       free(dirs->entry);
+
+                       ret = sqfs_search_dir(dirs, sym_tokens, token_count,
+                                             m_list, m_count);
+                       return ret;
+               } else if (!sqfs_is_dir(get_unaligned_le16(&dir->inode_type))) {
+                       printf("** Cannot find directory. **\n");
+                       free(dirs->entry);
+                       return -EINVAL;
+               }
+
+               /* Check if it is an extended dir. */
+               if (get_unaligned_le16(&dir->inode_type) == SQFS_LDIR_TYPE)
+                       ldir = (struct squashfs_ldir_inode *)table;
+
+               /* Get dir. offset into the directory table */
+               offset = sqfs_dir_offset(table, m_list, m_count);
+               dirs->table = &dirs->dir_table[offset];
+
+               /* Copy directory header */
+               memcpy(dirs->dir_header, &dirs->dir_table[offset],
+                      SQFS_DIR_HEADER_SIZE);
+
+               /* Check for empty directory */
+               if (sqfs_is_empty_dir(table)) {
+                       printf("Empty directory.\n");
+                       free(dirs->entry);
+                       return SQFS_EMPTY_DIR;
+               }
+
+               dirs->table += SQFS_DIR_HEADER_SIZE;
+               dirs->size = get_unaligned_le16(&dir->file_size);
+               dirs->entry_count = dirs->dir_header->count + 1;
+               dirs->size -= SQFS_DIR_HEADER_SIZE;
+               free(dirs->entry);
+       }
+
+       offset = sqfs_dir_offset(table, m_list, m_count);
+       dirs->table = &dirs->dir_table[offset];
+
+       if (get_unaligned_le16(&dir->inode_type) == SQFS_DIR_TYPE)
+               memcpy(&dirs->i_dir, dir, sizeof(*dir));
+       else
+               memcpy(&dirs->i_ldir, ldir, sizeof(*ldir));
+
+       return 0;
+}
+
+/*
+ * Inode and directory tables are stored as a series of metadata blocks, and
+ * given the compressed size of this table, we can calculate how much metadata
+ * blocks are needed to store the result of the decompression, since a
+ * decompressed metadata block should have a size of 8KiB.
+ */
+static int sqfs_count_metablks(void *table, u32 offset, int table_size)
+{
+       int count = 0, cur_size = 0, ret;
+       u32 data_size;
+       bool comp;
+
+       do {
+               ret = sqfs_read_metablock(table, offset + cur_size, &comp,
+                                         &data_size);
+               if (ret)
+                       return -EINVAL;
+               cur_size += data_size + SQFS_HEADER_SIZE;
+               count++;
+       } while (cur_size < table_size);
+
+       return count;
+}
+
+/*
+ * Storing the metadata blocks header's positions will be useful while looking
+ * for an entry in the directory table, using the reference (index and offset)
+ * given by its inode.
+ */
+static int sqfs_get_metablk_pos(u32 *pos_list, void *table, u32 offset,
+                               int metablks_count)
+{
+       u32 data_size, cur_size = 0;
+       int j, ret = 0;
+       bool comp;
+
+       if (!metablks_count)
+               return -EINVAL;
+
+       for (j = 0; j < metablks_count; j++) {
+               ret = sqfs_read_metablock(table, offset + cur_size, &comp,
+                                         &data_size);
+               if (ret)
+                       return -EINVAL;
+
+               cur_size += data_size + SQFS_HEADER_SIZE;
+               pos_list[j] = cur_size;
+       }
+
+       return ret;
+}
+
+static int sqfs_read_inode_table(unsigned char **inode_table)
+{
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       u64 start, n_blks, table_offset, table_size;
+       int j, ret = 0, metablks_count, comp_type;
+       unsigned char *src_table, *itb;
+       u32 src_len, dest_offset = 0;
+       unsigned long dest_len;
+       bool compressed;
+
+       comp_type = get_unaligned_le16(&sblk->compression);
+       table_size = get_unaligned_le64(&sblk->directory_table_start) -
+               get_unaligned_le64(&sblk->inode_table_start);
+       start = get_unaligned_le64(&sblk->inode_table_start) /
+               ctxt.cur_dev->blksz;
+       n_blks = sqfs_calc_n_blks(sblk->inode_table_start,
+                                 sblk->directory_table_start, &table_offset);
+
+       /* Allocate a proper sized buffer (itb) to store the inode table */
+       itb = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+       if (!itb)
+               return -ENOMEM;
+
+       if (sqfs_disk_read(start, n_blks, itb) < 0) {
+               ret = -EINVAL;
+               goto free_itb;
+       }
+
+       /* Parse inode table (metadata block) header */
+       ret = sqfs_read_metablock(itb, table_offset, &compressed, &src_len);
+       if (ret) {
+               ret = -EINVAL;
+               goto free_itb;
+       }
+
+       /* Calculate size to store the whole decompressed table */
+       metablks_count = sqfs_count_metablks(itb, table_offset, table_size);
+       if (metablks_count < 1) {
+               ret = -EINVAL;
+               goto free_itb;
+       }
+
+       *inode_table = malloc(metablks_count * SQFS_METADATA_BLOCK_SIZE);
+       if (!*inode_table) {
+               ret = -ENOMEM;
+               goto free_itb;
+       }
+
+       src_table = itb + table_offset + SQFS_HEADER_SIZE;
+
+       /* Extract compressed Inode table */
+       for (j = 0; j < metablks_count; j++) {
+               sqfs_read_metablock(itb, table_offset, &compressed, &src_len);
+               if (compressed) {
+                       dest_len = SQFS_METADATA_BLOCK_SIZE;
+                       ret = sqfs_decompress(comp_type, *inode_table +
+                                             dest_offset, &dest_len,
+                                             src_table, src_len);
+                       if (ret) {
+                               free(*inode_table);
+                               goto free_itb;
+                       }
+
+               } else {
+                       memcpy(*inode_table + (j * SQFS_METADATA_BLOCK_SIZE),
+                              src_table, src_len);
+               }
+
+               /*
+                * Offsets to the decompression destination, to the metadata
+                * buffer 'itb' and to the decompression source, respectively.
+                */
+               dest_offset += dest_len;
+               table_offset += src_len + SQFS_HEADER_SIZE;
+               src_table += src_len + SQFS_HEADER_SIZE;
+       }
+
+free_itb:
+       free(itb);
+
+       return ret;
+}
+
+static int sqfs_read_directory_table(unsigned char **dir_table, u32 **pos_list)
+{
+       u64 start, n_blks, table_offset, table_size;
+       int j, ret = 0, metablks_count = -1, comp_type;
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       unsigned char *src_table, *dtb;
+       u32 src_len, dest_offset = 0;
+       unsigned long dest_len;
+       bool compressed;
+
+       comp_type = get_unaligned_le16(&sblk->compression);
+
+       /* DIRECTORY TABLE */
+       table_size = get_unaligned_le64(&sblk->fragment_table_start) -
+               get_unaligned_le64(&sblk->directory_table_start);
+       start = get_unaligned_le64(&sblk->directory_table_start) /
+               ctxt.cur_dev->blksz;
+       n_blks = sqfs_calc_n_blks(sblk->directory_table_start,
+                                 sblk->fragment_table_start, &table_offset);
+
+       /* Allocate a proper sized buffer (dtb) to store the directory table */
+       dtb = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+       if (!dtb)
+               return -ENOMEM;
+
+       if (sqfs_disk_read(start, n_blks, dtb) < 0)
+               goto free_dtb;
+
+       /* Parse directory table (metadata block) header */
+       ret = sqfs_read_metablock(dtb, table_offset, &compressed, &src_len);
+       if (ret)
+               goto free_dtb;
+
+       /* Calculate total size to store the whole decompressed table */
+       metablks_count = sqfs_count_metablks(dtb, table_offset, table_size);
+       if (metablks_count < 1)
+               goto free_dtb;
+
+       *dir_table = malloc(metablks_count * SQFS_METADATA_BLOCK_SIZE);
+       if (!*dir_table)
+               goto free_dtb;
+
+       *pos_list = malloc(metablks_count * sizeof(u32));
+       if (!*pos_list) {
+               free(*dir_table);
+               goto free_dtb;
+       }
+
+       ret = sqfs_get_metablk_pos(*pos_list, dtb, table_offset,
+                                  metablks_count);
+       if (ret) {
+               metablks_count = -1;
+               free(*dir_table);
+               free(*pos_list);
+               goto free_dtb;
+       }
+
+       src_table = dtb + table_offset + SQFS_HEADER_SIZE;
+
+       /* Extract compressed Directory table */
+       dest_offset = 0;
+       for (j = 0; j < metablks_count; j++) {
+               sqfs_read_metablock(dtb, table_offset, &compressed, &src_len);
+               if (compressed) {
+                       dest_len = SQFS_METADATA_BLOCK_SIZE;
+                       ret = sqfs_decompress(comp_type, *dir_table +
+                                             (j * SQFS_METADATA_BLOCK_SIZE),
+                                             &dest_len, src_table, src_len);
+                       if (ret) {
+                               metablks_count = -1;
+                               free(*dir_table);
+                               goto free_dtb;
+                       }
+
+                       if (dest_len < SQFS_METADATA_BLOCK_SIZE) {
+                               dest_offset += dest_len;
+                               break;
+                       }
+               } else {
+                       memcpy(*dir_table + (j * SQFS_METADATA_BLOCK_SIZE),
+                              src_table, src_len);
+               }
+
+               /*
+                * Offsets to the decompression destination, to the metadata
+                * buffer 'dtb' and to the decompression source, respectively.
+                */
+               dest_offset += dest_len;
+               table_offset += src_len + SQFS_HEADER_SIZE;
+               src_table += src_len + SQFS_HEADER_SIZE;
+       }
+
+free_dtb:
+       free(dtb);
+
+       return metablks_count;
+}
+
+int sqfs_opendir(const char *filename, struct fs_dir_stream **dirsp)
+{
+       unsigned char *inode_table = NULL, *dir_table = NULL;
+       int j, token_count, ret = 0, metablks_count;
+       struct squashfs_dir_stream *dirs;
+       char **token_list, *path;
+       u32 *pos_list = NULL;
+
+       dirs = malloc(sizeof(*dirs));
+       if (!dirs)
+               return -EINVAL;
+
+       ret = sqfs_read_inode_table(&inode_table);
+       if (ret)
+               return -EINVAL;
+
+       metablks_count = sqfs_read_directory_table(&dir_table, &pos_list);
+       if (metablks_count < 1)
+               return -EINVAL;
+
+       /* Tokenize filename */
+       token_count = sqfs_count_tokens(filename);
+       if (token_count < 0)
+               return -EINVAL;
+
+       path = strdup(filename);
+       if (!path)
+               return -ENOMEM;
+
+       token_list = malloc(token_count * sizeof(char *));
+       if (!token_list) {
+               ret = -EINVAL;
+               goto free_path;
+       }
+
+       /* Fill tokens list */
+       ret = sqfs_tokenize(token_list, token_count, path);
+       if (ret)
+               goto free_tokens;
+       /*
+        * ldir's (extended directory) size is greater than dir, so it works as
+        * a general solution for the malloc size, since 'i' is a union.
+        */
+       dirs->inode_table = inode_table;
+       dirs->dir_table = dir_table;
+       ret = sqfs_search_dir(dirs, token_list, token_count, pos_list,
+                             metablks_count);
+       if (ret)
+               goto free_tokens;
+
+       if (le16_to_cpu(dirs->i_dir.inode_type) == SQFS_DIR_TYPE)
+               dirs->size = le16_to_cpu(dirs->i_dir.file_size);
+       else
+               dirs->size = le32_to_cpu(dirs->i_ldir.file_size);
+
+       /* Setup directory header */
+       memcpy(dirs->dir_header, dirs->table, SQFS_DIR_HEADER_SIZE);
+       dirs->entry_count = dirs->dir_header->count + 1;
+       dirs->size -= SQFS_DIR_HEADER_SIZE;
+
+       /* Setup entry */
+       dirs->entry = NULL;
+       dirs->table += SQFS_DIR_HEADER_SIZE;
+
+       *dirsp = (struct fs_dir_stream *)dirs;
+
+free_tokens:
+       for (j = 0; j < token_count; j++)
+               free(token_list[j]);
+       free(token_list);
+       free(pos_list);
+free_path:
+       free(path);
+
+       return ret;
+}
+
+int sqfs_readdir(struct fs_dir_stream *fs_dirs, struct fs_dirent **dentp)
+{
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       struct squashfs_dir_stream *dirs;
+       struct squashfs_lreg_inode *lreg;
+       struct squashfs_base_inode *base;
+       struct squashfs_reg_inode *reg;
+       int i_number, offset = 0, ret;
+       struct fs_dirent *dent;
+       unsigned char *ipos;
+
+       dirs = (struct squashfs_dir_stream *)fs_dirs;
+       if (!dirs->size) {
+               *dentp = NULL;
+               return -SQFS_STOP_READDIR;
+       }
+
+       dent = &dirs->dentp;
+
+       if (!dirs->entry_count) {
+               if (dirs->size > SQFS_DIR_HEADER_SIZE) {
+                       dirs->size -= SQFS_DIR_HEADER_SIZE;
+               } else {
+                       *dentp = NULL;
+                       dirs->size = 0;
+                       return -SQFS_STOP_READDIR;
+               }
+
+               if (dirs->size > SQFS_EMPTY_FILE_SIZE) {
+                       /* Read follow-up (emitted) dir. header */
+                       memcpy(dirs->dir_header, dirs->table,
+                              SQFS_DIR_HEADER_SIZE);
+                       dirs->entry_count = dirs->dir_header->count + 1;
+                       ret = sqfs_read_entry(&dirs->entry, dirs->table +
+                                             SQFS_DIR_HEADER_SIZE);
+                       if (ret)
+                               return -SQFS_STOP_READDIR;
+
+                       dirs->table += SQFS_DIR_HEADER_SIZE;
+               }
+       } else {
+               ret = sqfs_read_entry(&dirs->entry, dirs->table);
+               if (ret)
+                       return -SQFS_STOP_READDIR;
+       }
+
+       i_number = dirs->dir_header->inode_number + dirs->entry->inode_offset;
+       ipos = sqfs_find_inode(dirs->inode_table, i_number, sblk->inodes,
+                              sblk->block_size);
+
+       base = (struct squashfs_base_inode *)ipos;
+
+       /* Set entry type and size */
+       switch (dirs->entry->type) {
+       case SQFS_DIR_TYPE:
+       case SQFS_LDIR_TYPE:
+               dent->type = FS_DT_DIR;
+               break;
+       case SQFS_REG_TYPE:
+       case SQFS_LREG_TYPE:
+               /*
+                * Entries do not differentiate extended from regular types, so
+                * it needs to be verified manually.
+                */
+               if (get_unaligned_le16(&base->inode_type) == SQFS_LREG_TYPE) {
+                       lreg = (struct squashfs_lreg_inode *)ipos;
+                       dent->size = get_unaligned_le64(&lreg->file_size);
+               } else {
+                       reg = (struct squashfs_reg_inode *)ipos;
+                       dent->size = get_unaligned_le32(&reg->file_size);
+               }
+
+               dent->type = FS_DT_REG;
+               break;
+       case SQFS_BLKDEV_TYPE:
+       case SQFS_CHRDEV_TYPE:
+       case SQFS_LBLKDEV_TYPE:
+       case SQFS_LCHRDEV_TYPE:
+       case SQFS_FIFO_TYPE:
+       case SQFS_SOCKET_TYPE:
+       case SQFS_LFIFO_TYPE:
+       case SQFS_LSOCKET_TYPE:
+               dent->type = SQFS_MISC_ENTRY_TYPE;
+               break;
+       case SQFS_SYMLINK_TYPE:
+       case SQFS_LSYMLINK_TYPE:
+               dent->type = FS_DT_LNK;
+               break;
+       default:
+               return -SQFS_STOP_READDIR;
+       }
+
+       /* Set entry name */
+       strncpy(dent->name, dirs->entry->name, dirs->entry->name_size + 1);
+       dent->name[dirs->entry->name_size + 1] = '\0';
+
+       offset = dirs->entry->name_size + 1 + SQFS_ENTRY_BASE_LENGTH;
+       dirs->entry_count--;
+
+       /* Decrement size to be read */
+       if (dirs->size > offset)
+               dirs->size -= offset;
+       else
+               dirs->size = 0;
+
+       /* Keep a reference to the current entry before incrementing it */
+       dirs->table += offset;
+
+       *dentp = dent;
+
+       return 0;
+}
+
+int sqfs_probe(struct blk_desc *fs_dev_desc, struct disk_partition *fs_partition)
+{
+       struct squashfs_super_block *sblk;
+       int ret;
+
+       ctxt.cur_dev = fs_dev_desc;
+       ctxt.cur_part_info = *fs_partition;
+
+       ret = sqfs_read_sblk(&sblk);
+       if (ret)
+               return ret;
+
+       /* Make sure it has a valid SquashFS magic number*/
+       if (get_unaligned_le32(&sblk->s_magic) != SQFS_MAGIC_NUMBER) {
+               printf("Bad magic number for SquashFS image.\n");
+               ctxt.cur_dev = NULL;
+               return -EINVAL;
+       }
+
+       ctxt.sblk = sblk;
+
+       return 0;
+}
+
+static char *sqfs_basename(char *path)
+{
+       char *fname;
+
+       fname = path + strlen(path) - 1;
+       while (fname >= path) {
+               if (*fname == '/') {
+                       fname++;
+                       break;
+               }
+
+               fname--;
+       }
+
+       return fname;
+}
+
+static char *sqfs_dirname(char *path)
+{
+       char *fname;
+
+       fname = sqfs_basename(path);
+       --fname;
+       *fname = '\0';
+
+       return path;
+}
+
+/*
+ * Takes a path to file and splits it in two parts: the filename itself and the
+ * directory's path, e.g.:
+ * path: /path/to/file.txt
+ * file: file.txt
+ * dir: /path/to
+ */
+static int sqfs_split_path(char **file, char **dir, const char *path)
+{
+       char *dirc, *basec, *bname, *dname, *tmp_path;
+       int ret = 0;
+
+       /* check for first slash in path*/
+       if (path[0] == '/') {
+               tmp_path = strdup(path);
+               if (!tmp_path)
+                       return -ENOMEM;
+       } else {
+               tmp_path = malloc(strlen(path) + 2);
+               if (!tmp_path)
+                       return -ENOMEM;
+               tmp_path[0] = '/';
+               strcpy(tmp_path + 1, path);
+       }
+
+       /* String duplicates */
+       dirc = strdup(tmp_path);
+       if (!dirc) {
+               ret = -ENOMEM;
+               goto free_tmp;
+       }
+
+       basec = strdup(tmp_path);
+       if (!basec) {
+               ret = -ENOMEM;
+               goto free_dirc;
+       }
+
+       dname = sqfs_dirname(dirc);
+       bname = sqfs_basename(basec);
+
+       *file = strdup(bname);
+
+       if (!*file) {
+               ret = -ENOMEM;
+               goto free_basec;
+       }
+
+       if (*dname == '\0') {
+               *dir = malloc(2);
+               if (!*dir) {
+                       ret = -ENOMEM;
+                       goto free_basec;
+               }
+
+               (*dir)[0] = '/';
+               (*dir)[1] = '\0';
+       } else {
+               *dir = strdup(dname);
+               if (!*dir) {
+                       ret = -ENOMEM;
+                       goto free_basec;
+               }
+       }
+
+free_basec:
+       free(basec);
+free_dirc:
+       free(dirc);
+free_tmp:
+       free(tmp_path);
+
+       return ret;
+}
+
+static int sqfs_get_regfile_info(struct squashfs_reg_inode *reg,
+                                struct squashfs_file_info *finfo,
+                                struct squashfs_fragment_block_entry *fentry,
+                                __le32 blksz)
+{
+       int datablk_count = 0, ret;
+
+       finfo->size = get_unaligned_le32(&reg->file_size);
+       finfo->offset = get_unaligned_le32(&reg->offset);
+       finfo->start = get_unaligned_le32(&reg->start_block);
+       finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&reg->fragment));
+
+       if (finfo->frag) {
+               datablk_count = finfo->size / le32_to_cpu(blksz);
+               ret = sqfs_frag_lookup(get_unaligned_le32(&reg->fragment),
+                                      fentry);
+               if (ret < 0)
+                       return -EINVAL;
+               finfo->comp = true;
+       } else {
+               datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));
+       }
+
+       finfo->blk_sizes = malloc(datablk_count * sizeof(u32));
+       if (!finfo->blk_sizes)
+               return -ENOMEM;
+
+       return datablk_count;
+}
+
+static int sqfs_get_lregfile_info(struct squashfs_lreg_inode *lreg,
+                                 struct squashfs_file_info *finfo,
+                                 struct squashfs_fragment_block_entry *fentry,
+                                __le32 blksz)
+{
+       int datablk_count = 0, ret;
+
+       finfo->size = get_unaligned_le64(&lreg->file_size);
+       finfo->offset = get_unaligned_le32(&lreg->offset);
+       finfo->start = get_unaligned_le64(&lreg->start_block);
+       finfo->frag = SQFS_IS_FRAGMENTED(get_unaligned_le32(&lreg->fragment));
+
+       if (finfo->frag) {
+               datablk_count = finfo->size / le32_to_cpu(blksz);
+               ret = sqfs_frag_lookup(get_unaligned_le32(&lreg->fragment),
+                                      fentry);
+               if (ret < 0)
+                       return -EINVAL;
+               finfo->comp = true;
+       } else {
+               datablk_count = DIV_ROUND_UP(finfo->size, le32_to_cpu(blksz));
+       }
+
+       finfo->blk_sizes = malloc(datablk_count * sizeof(u32));
+       if (!finfo->blk_sizes)
+               return -ENOMEM;
+
+       return datablk_count;
+}
+
+int sqfs_read(const char *filename, void *buf, loff_t offset, loff_t len,
+             loff_t *actread)
+{
+       char *dir, *fragment_block, *datablock = NULL, *data_buffer = NULL;
+       char *fragment, *file, *resolved, *data;
+       u64 start, n_blks, table_size, data_offset, table_offset;
+       int ret, j, i_number, comp_type, datablk_count = 0;
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       struct squashfs_fragment_block_entry frag_entry;
+       struct squashfs_file_info finfo = {0};
+       struct squashfs_symlink_inode *symlink;
+       struct fs_dir_stream *dirsp = NULL;
+       struct squashfs_dir_stream *dirs;
+       struct squashfs_lreg_inode *lreg;
+       struct squashfs_base_inode *base;
+       struct squashfs_reg_inode *reg;
+       unsigned long dest_len;
+       struct fs_dirent *dent;
+       unsigned char *ipos;
+
+       *actread = 0;
+
+       comp_type = get_unaligned_le16(&sblk->compression);
+
+       /*
+        * sqfs_opendir will uncompress inode and directory tables, and will
+        * return a pointer to the directory that contains the requested file.
+        */
+       sqfs_split_path(&file, &dir, filename);
+       ret = sqfs_opendir(dir, &dirsp);
+       if (ret) {
+               sqfs_closedir(dirsp);
+               goto free_paths;
+       }
+
+       dirs = (struct squashfs_dir_stream *)dirsp;
+
+       /* For now, only regular files are able to be loaded */
+       while (!sqfs_readdir(dirsp, &dent)) {
+               ret = strcmp(dent->name, file);
+               if (!ret)
+                       break;
+
+               free(dirs->entry);
+       }
+
+       if (ret) {
+               printf("File not found.\n");
+               *actread = 0;
+               sqfs_closedir(dirsp);
+               ret = -ENOENT;
+               goto free_paths;
+       }
+
+       i_number = dirs->dir_header->inode_number + dirs->entry->inode_offset;
+       ipos = sqfs_find_inode(dirs->inode_table, i_number, sblk->inodes,
+                              sblk->block_size);
+
+       base = (struct squashfs_base_inode *)ipos;
+       switch (get_unaligned_le16(&base->inode_type)) {
+       case SQFS_REG_TYPE:
+               reg = (struct squashfs_reg_inode *)ipos;
+               datablk_count = sqfs_get_regfile_info(reg, &finfo, &frag_entry,
+                                                     sblk->block_size);
+               if (datablk_count < 0) {
+                       ret = -EINVAL;
+                       goto free_paths;
+               }
+
+               memcpy(finfo.blk_sizes, ipos + sizeof(*reg),
+                      datablk_count * sizeof(u32));
+               break;
+       case SQFS_LREG_TYPE:
+               lreg = (struct squashfs_lreg_inode *)ipos;
+               datablk_count = sqfs_get_lregfile_info(lreg, &finfo,
+                                                      &frag_entry,
+                                                      sblk->block_size);
+               if (datablk_count < 0) {
+                       ret = -EINVAL;
+                       goto free_paths;
+               }
+
+               memcpy(finfo.blk_sizes, ipos + sizeof(*lreg),
+                      datablk_count * sizeof(u32));
+               break;
+       case SQFS_SYMLINK_TYPE:
+       case SQFS_LSYMLINK_TYPE:
+               symlink = (struct squashfs_symlink_inode *)ipos;
+               resolved = sqfs_resolve_symlink(symlink, filename);
+               ret = sqfs_read(resolved, buf, offset, len, actread);
+               free(resolved);
+               goto free_paths;
+       case SQFS_BLKDEV_TYPE:
+       case SQFS_CHRDEV_TYPE:
+       case SQFS_LBLKDEV_TYPE:
+       case SQFS_LCHRDEV_TYPE:
+       case SQFS_FIFO_TYPE:
+       case SQFS_SOCKET_TYPE:
+       case SQFS_LFIFO_TYPE:
+       case SQFS_LSOCKET_TYPE:
+       default:
+               printf("Unsupported entry type\n");
+               ret = -EINVAL;
+               goto free_paths;
+       }
+
+       /* If the user specifies a length, check its sanity */
+       if (len) {
+               if (len > finfo.size) {
+                       ret = -EINVAL;
+                       goto free_paths;
+               }
+
+               finfo.size = len;
+       }
+
+       if (datablk_count) {
+               data_offset = finfo.start;
+               datablock = malloc(get_unaligned_le32(&sblk->block_size));
+               if (!datablock) {
+                       ret = -ENOMEM;
+                       goto free_paths;
+               }
+       }
+
+       for (j = 0; j < datablk_count; j++) {
+               start = data_offset / ctxt.cur_dev->blksz;
+               table_size = SQFS_BLOCK_SIZE(finfo.blk_sizes[j]);
+               table_offset = data_offset - (start * ctxt.cur_dev->blksz);
+               n_blks = DIV_ROUND_UP(table_size + table_offset,
+                                     ctxt.cur_dev->blksz);
+
+               data_buffer = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+
+               if (!data_buffer) {
+                       ret = -ENOMEM;
+                       goto free_datablk;
+               }
+
+               ret = sqfs_disk_read(start, n_blks, data_buffer);
+               if (ret < 0) {
+                       /*
+                        * Possible causes: too many data blocks or too large
+                        * SquashFS block size. Tip: re-compile the SquashFS
+                        * image with mksquashfs's -b <block_size> option.
+                        */
+                       printf("Error: too many data blocks to be read.\n");
+                       goto free_buffer;
+               }
+
+               data = data_buffer + table_offset;
+
+               /* Load the data */
+               if (SQFS_COMPRESSED_BLOCK(finfo.blk_sizes[j])) {
+                       dest_len = get_unaligned_le32(&sblk->block_size);
+                       ret = sqfs_decompress(comp_type, datablock, &dest_len,
+                                             data, table_size);
+                       if (ret)
+                               goto free_buffer;
+
+                       memcpy(buf + offset + *actread, datablock, dest_len);
+                       *actread += dest_len;
+               } else {
+                       memcpy(buf + offset + *actread, data, table_size);
+                       *actread += table_size;
+               }
+
+               data_offset += table_size;
+       }
+
+       free(finfo.blk_sizes);
+
+       /*
+        * There is no need to continue if the file is not fragmented.
+        */
+       if (!finfo.frag) {
+               ret = 0;
+               goto free_buffer;
+       }
+
+       start = frag_entry.start / ctxt.cur_dev->blksz;
+       table_size = SQFS_BLOCK_SIZE(frag_entry.size);
+       table_offset = frag_entry.start - (start * ctxt.cur_dev->blksz);
+       n_blks = DIV_ROUND_UP(table_size + table_offset, ctxt.cur_dev->blksz);
+
+       fragment = malloc_cache_aligned(n_blks * ctxt.cur_dev->blksz);
+
+       if (!fragment) {
+               ret = -ENOMEM;
+               goto free_buffer;
+       }
+
+       ret = sqfs_disk_read(start, n_blks, fragment);
+       if (ret < 0)
+               goto free_fragment;
+
+       /* File compressed and fragmented */
+       if (finfo.frag && finfo.comp) {
+               dest_len = get_unaligned_le32(&sblk->block_size);
+               fragment_block = malloc(dest_len);
+               if (!fragment_block) {
+                       ret = -ENOMEM;
+                       goto free_fragment;
+               }
+
+               ret = sqfs_decompress(comp_type, fragment_block, &dest_len,
+                                     (void *)fragment  + table_offset,
+                                     frag_entry.size);
+               if (ret) {
+                       free(fragment_block);
+                       goto free_fragment;
+               }
+
+               for (j = offset + *actread; j < finfo.size; j++) {
+                       memcpy(buf + j, &fragment_block[finfo.offset + j], 1);
+                       (*actread)++;
+               }
+
+               free(fragment_block);
+
+       } else if (finfo.frag && !finfo.comp) {
+               fragment_block = (void *)fragment + table_offset;
+
+               for (j = offset + *actread; j < finfo.size; j++) {
+                       memcpy(buf + j, &fragment_block[finfo.offset + j], 1);
+                       (*actread)++;
+               }
+       }
+
+free_fragment:
+       free(fragment);
+free_buffer:
+       if (datablk_count)
+               free(data_buffer);
+free_datablk:
+       if (datablk_count)
+               free(datablock);
+free_paths:
+       free(file);
+       free(dir);
+
+       return ret;
+}
+
+int sqfs_size(const char *filename, loff_t *size)
+{
+       struct squashfs_super_block *sblk = ctxt.sblk;
+       struct squashfs_symlink_inode *symlink;
+       struct fs_dir_stream *dirsp = NULL;
+       struct squashfs_base_inode *base;
+       struct squashfs_dir_stream *dirs;
+       struct squashfs_lreg_inode *lreg;
+       struct squashfs_reg_inode *reg;
+       char *dir, *file, *resolved;
+       struct fs_dirent *dent;
+       unsigned char *ipos;
+       int ret, i_number;
+
+       sqfs_split_path(&file, &dir, filename);
+       /*
+        * sqfs_opendir will uncompress inode and directory tables, and will
+        * return a pointer to the directory that contains the requested file.
+        */
+       ret = sqfs_opendir(dir, &dirsp);
+       if (ret) {
+               sqfs_closedir(dirsp);
+               ret = -EINVAL;
+               goto free_strings;
+       }
+
+       dirs = (struct squashfs_dir_stream *)dirsp;
+
+       while (!sqfs_readdir(dirsp, &dent)) {
+               ret = strcmp(dent->name, file);
+               if (!ret)
+                       break;
+               free(dirs->entry);
+       }
+
+       if (ret) {
+               printf("File not found.\n");
+               *size = 0;
+               ret = -EINVAL;
+               goto free_strings;
+       }
+
+       i_number = dirs->dir_header->inode_number + dirs->entry->inode_offset;
+       ipos = sqfs_find_inode(dirs->inode_table, i_number, sblk->inodes,
+                              sblk->block_size);
+       free(dirs->entry);
+
+       base = (struct squashfs_base_inode *)ipos;
+       switch (get_unaligned_le16(&base->inode_type)) {
+       case SQFS_REG_TYPE:
+               reg = (struct squashfs_reg_inode *)ipos;
+               *size = get_unaligned_le32(&reg->file_size);
+               break;
+       case SQFS_LREG_TYPE:
+               lreg = (struct squashfs_lreg_inode *)ipos;
+               *size = get_unaligned_le64(&lreg->file_size);
+               break;
+       case SQFS_SYMLINK_TYPE:
+       case SQFS_LSYMLINK_TYPE:
+               symlink = (struct squashfs_symlink_inode *)ipos;
+               resolved = sqfs_resolve_symlink(symlink, filename);
+               ret = sqfs_size(resolved, size);
+               free(resolved);
+               break;
+       case SQFS_BLKDEV_TYPE:
+       case SQFS_CHRDEV_TYPE:
+       case SQFS_LBLKDEV_TYPE:
+       case SQFS_LCHRDEV_TYPE:
+       case SQFS_FIFO_TYPE:
+       case SQFS_SOCKET_TYPE:
+       case SQFS_LFIFO_TYPE:
+       case SQFS_LSOCKET_TYPE:
+       default:
+               printf("Unable to recover entry's size.\n");
+               *size = 0;
+               ret = -EINVAL;
+               break;
+       }
+
+free_strings:
+       free(dir);
+       free(file);
+
+       sqfs_closedir(dirsp);
+
+       return ret;
+}
+
+void sqfs_close(void)
+{
+       free(ctxt.sblk);
+       ctxt.cur_dev = NULL;
+}
+
+void sqfs_closedir(struct fs_dir_stream *dirs)
+{
+       struct squashfs_dir_stream *sqfs_dirs;
+
+       sqfs_dirs = (struct squashfs_dir_stream *)dirs;
+       free(sqfs_dirs->inode_table);
+       free(sqfs_dirs->dir_table);
+       free(sqfs_dirs->dir_header);
+}
diff --git a/fs/squashfs/sqfs_decompressor.c b/fs/squashfs/sqfs_decompressor.c
new file mode 100644 (file)
index 0000000..a899a57
--- /dev/null
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "sqfs_decompressor.h"
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+int sqfs_decompress(u16 comp_type, void *dest, unsigned long *dest_len,
+                   void *source, u32 lenp)
+{
+       int ret = 0;
+
+       switch (comp_type) {
+       default:
+               printf("Error: unknown compression type.\n");
+               return -EINVAL;
+       }
+
+       return ret;
+}
diff --git a/fs/squashfs/sqfs_decompressor.h b/fs/squashfs/sqfs_decompressor.h
new file mode 100644 (file)
index 0000000..378965d
--- /dev/null
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#ifndef SQFS_DECOMPRESSOR_H
+#define SQFS_DECOMPRESSOR_H
+
+#include <stdint.h>
+
+#define SQFS_COMP_ZLIB 1
+#define SQFS_COMP_LZMA 2
+#define SQFS_COMP_LZO 3
+#define SQFS_COMP_XZ 4
+#define SQFS_COMP_LZ4 5
+#define SQFS_COMP_ZSTD 6
+
+/* LZMA does not support any compression options */
+
+struct squashfs_gzip_opts {
+       u32 compression_level;
+       u16 window_size;
+       u16 strategies;
+};
+
+struct squashfs_xz_opts {
+       u32 dictionary_size;
+       u32 executable_filters;
+};
+
+struct squashfs_lz4_opts {
+       u32 version;
+       u32 flags;
+};
+
+struct squashfs_zstd_opts {
+       u32 compression_level;
+};
+
+struct squashfs_lzo_opts {
+       u32 algorithm;
+       u32 level;
+};
+
+union squashfs_compression_opts {
+       struct squashfs_gzip_opts *gzip;
+       struct squashfs_xz_opts *xz;
+       struct squashfs_lz4_opts *lz4;
+       struct squashfs_zstd_opts *zstd;
+       struct squashfs_lzo_opts *lzo;
+};
+
+int sqfs_decompress(u16 comp_type, void *dest, unsigned long *dest_len,
+                   void *source, u32 lenp);
+
+#endif /* SQFS_DECOMPRESSOR_H */
diff --git a/fs/squashfs/sqfs_dir.c b/fs/squashfs/sqfs_dir.c
new file mode 100644 (file)
index 0000000..5f7660a
--- /dev/null
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/byteorder/little_endian.h>
+#include <linux/byteorder/generic.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+bool sqfs_is_dir(u16 type)
+{
+       return type == SQFS_DIR_TYPE || type == SQFS_LDIR_TYPE;
+}
+
+/*
+ * Receives a pointer (void *) to a position in the inode table containing the
+ * directory's inode. Returns directory inode offset into the directory table.
+ * m_list contains each metadata block's position, and m_count is the number of
+ * elements of m_list. Those metadata blocks come from the compressed directory
+ * table.
+ */
+int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count)
+{
+       struct squashfs_base_inode *base = dir_i;
+       struct squashfs_ldir_inode *ldir;
+       struct squashfs_dir_inode *dir;
+       u32 start_block;
+       u16 offset;
+       int j;
+
+       switch (get_unaligned_le16(&base->inode_type)) {
+       case SQFS_DIR_TYPE:
+               dir = (struct squashfs_dir_inode *)base;
+               start_block = get_unaligned_le32(&dir->start_block);
+               offset = get_unaligned_le16(&dir->offset);
+               break;
+       case SQFS_LDIR_TYPE:
+               ldir = (struct squashfs_ldir_inode *)base;
+               start_block = get_unaligned_le32(&ldir->start_block);
+               offset = get_unaligned_le16(&ldir->offset);
+               break;
+       default:
+               printf("Error: this is not a directory.\n");
+               return -EINVAL;
+       }
+
+       for (j = 0; j < m_count; j++) {
+               if (m_list[j] == start_block)
+                       return (++j * SQFS_METADATA_BLOCK_SIZE) + offset;
+       }
+
+       if (start_block == 0)
+               return offset;
+
+       printf("Error: invalid inode reference to directory table.\n");
+
+       return -EINVAL;
+}
+
+bool sqfs_is_empty_dir(void *dir_i)
+{
+       struct squashfs_base_inode *base = dir_i;
+       struct squashfs_ldir_inode *ldir;
+       struct squashfs_dir_inode *dir;
+       u32 file_size;
+
+       switch (get_unaligned_le16(&base->inode_type)) {
+       case SQFS_DIR_TYPE:
+               dir = (struct squashfs_dir_inode *)base;
+               file_size = get_unaligned_le16(&dir->file_size);
+               break;
+       case SQFS_LDIR_TYPE:
+               ldir = (struct squashfs_ldir_inode *)base;
+               file_size = get_unaligned_le16(&ldir->file_size);
+               break;
+       default:
+               printf("Error: this is not a directory.\n");
+               return false;
+       }
+
+       return file_size == SQFS_EMPTY_FILE_SIZE;
+}
diff --git a/fs/squashfs/sqfs_filesystem.h b/fs/squashfs/sqfs_filesystem.h
new file mode 100644 (file)
index 0000000..d63e3a4
--- /dev/null
@@ -0,0 +1,300 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#ifndef SQFS_FILESYSTEM_H
+#define SQFS_FILESYSTEM_H
+
+#include <asm/unaligned.h>
+#include <stdint.h>
+#include <fs.h>
+
+#define SQFS_UNCOMPRESSED_DATA 0x0002
+#define SQFS_MAGIC_NUMBER 0x73717368
+/* The three first members of squashfs_dir_index make a total of 12 bytes */
+#define SQFS_DIR_INDEX_BASE_LENGTH 12
+/* size of metadata (inode and directory) blocks */
+#define SQFS_METADATA_BLOCK_SIZE 8192
+/* Max. number of fragment entries in a metadata block is 512 */
+#define SQFS_MAX_ENTRIES 512
+/* Metadata blocks start by a 2-byte length header */
+#define SQFS_HEADER_SIZE 2
+#define SQFS_LREG_INODE_MIN_SIZE 56
+#define SQFS_DIR_HEADER_SIZE 12
+#define SQFS_MISC_ENTRY_TYPE -1
+#define SQFS_EMPTY_FILE_SIZE 3
+#define SQFS_STOP_READDIR 1
+#define SQFS_EMPTY_DIR -1
+/*
+ * A directory entry object has a fixed length of 8 bytes, corresponding to its
+ * first four members, plus the size of the entry name, which is equal to
+ * 'entry_name' + 1 bytes.
+ */
+#define SQFS_ENTRY_BASE_LENGTH 8
+/* Inode types */
+#define SQFS_DIR_TYPE 1
+#define SQFS_REG_TYPE 2
+#define SQFS_SYMLINK_TYPE 3
+#define SQFS_BLKDEV_TYPE 4
+#define SQFS_CHRDEV_TYPE 5
+#define SQFS_FIFO_TYPE 6
+#define SQFS_SOCKET_TYPE 7
+#define SQFS_LDIR_TYPE 8
+#define SQFS_LREG_TYPE 9
+#define SQFS_LSYMLINK_TYPE 10
+#define SQFS_LBLKDEV_TYPE 11
+#define SQFS_LCHRDEV_TYPE 12
+#define SQFS_LFIFO_TYPE 13
+#define SQFS_LSOCKET_TYPE 14
+
+struct squashfs_super_block {
+       __le32 s_magic;
+       __le32 inodes;
+       __le32 mkfs_time;
+       __le32 block_size;
+       __le32 fragments;
+       __le16 compression;
+       __le16 block_log;
+       __le16 flags;
+       __le16 no_ids;
+       __le16 s_major;
+       __le16 s_minor;
+       __le64 root_inode;
+       __le64 bytes_used;
+       __le64 id_table_start;
+       __le64 xattr_id_table_start;
+       __le64 inode_table_start;
+       __le64 directory_table_start;
+       __le64 fragment_table_start;
+       __le64 export_table_start;
+};
+
+struct squashfs_directory_index {
+       u32 index;
+       u32 start;
+       u32 size;
+       char name[0];
+};
+
+struct squashfs_base_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+};
+
+struct squashfs_ipc_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+};
+
+struct squashfs_lipc_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+       __le32 xattr;
+};
+
+struct squashfs_dev_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+       __le32 rdev;
+};
+
+struct squashfs_ldev_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+       __le32 rdev;
+       __le32 xattr;
+};
+
+struct squashfs_symlink_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+       __le32 symlink_size;
+       char symlink[0];
+};
+
+struct squashfs_reg_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 start_block;
+       __le32 fragment;
+       __le32 offset;
+       __le32 file_size;
+       __le32 block_list[0];
+};
+
+struct squashfs_lreg_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le64 start_block;
+       __le64 file_size;
+       __le64 sparse;
+       __le32 nlink;
+       __le32 fragment;
+       __le32 offset;
+       __le32 xattr;
+       __le32 block_list[0];
+};
+
+struct squashfs_dir_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 start_block;
+       __le32 nlink;
+       __le16 file_size;
+       __le16 offset;
+       __le32 parent_inode;
+};
+
+struct squashfs_ldir_inode {
+       __le16 inode_type;
+       __le16 mode;
+       __le16 uid;
+       __le16 guid;
+       __le32 mtime;
+       __le32 inode_number;
+       __le32 nlink;
+       __le32 file_size;
+       __le32 start_block;
+       __le32 parent_inode;
+       __le16 i_count;
+       __le16 offset;
+       __le32 xattr;
+       struct squashfs_directory_index index[0];
+};
+
+union squashfs_inode {
+       struct squashfs_base_inode *base;
+       struct squashfs_dev_inode *dev;
+       struct squashfs_ldev_inode *ldev;
+       struct squashfs_symlink_inode *symlink;
+       struct squashfs_reg_inode *reg;
+       struct squashfs_lreg_inode *lreg;
+       struct squashfs_dir_inode *dir;
+       struct squashfs_ldir_inode *ldir;
+       struct squashfs_ipc_inode *ipc;
+       struct squashfs_lipc_inode *lipc;
+};
+
+struct squashfs_directory_entry {
+       u16 offset;
+       u16 inode_offset;
+       u16 type;
+       u16 name_size;
+       char name[0];
+};
+
+struct squashfs_directory_header {
+       u32 count;
+       u32 start;
+       u32 inode_number;
+};
+
+struct squashfs_fragment_block_entry {
+       u64 start;
+       u32 size;
+       u32 _unused;
+};
+
+struct squashfs_dir_stream {
+       struct fs_dir_stream fs_dirs;
+       struct fs_dirent dentp;
+       /*
+        * 'size' is the uncompressed size of the entire listing, including
+        * headers. 'entry_count' is the number of entries following a
+        * specific header. Both variables are decremented in sqfs_readdir() so
+        * the function knows when the end of the directory is reached.
+        */
+       size_t size;
+       int entry_count;
+       /* SquashFS structures */
+       struct squashfs_directory_header *dir_header;
+       struct squashfs_directory_entry *entry;
+       /*
+        * 'table' points to a position into the directory table. Both 'table'
+        * and 'inode' are defined for the first time in sqfs_opendir().
+        * 'table's value changes in sqfs_readdir().
+        */
+       unsigned char *table;
+       union squashfs_inode i;
+       struct squashfs_dir_inode i_dir;
+       struct squashfs_ldir_inode i_ldir;
+       /*
+        * References to the tables' beginnings. They are assigned in
+        * sqfs_opendir() and freed in sqfs_closedir().
+        */
+       unsigned char *inode_table;
+       unsigned char *dir_table;
+};
+
+struct squashfs_file_info {
+       /* File size in bytes (uncompressed) */
+       size_t size;
+       /* Reference to list of data blocks's sizes */
+       u32 *blk_sizes;
+       /* Offset into the fragment block */
+       u32 offset;
+       /* Offset in which the data blocks begin */
+       u64 start;
+       /* Is file fragmented? */
+       bool frag;
+       /* Compressed fragment */
+       bool comp;
+};
+
+void *sqfs_find_inode(void *inode_table, int inode_number, __le32 inode_count,
+                     __le32 block_size);
+
+int sqfs_dir_offset(void *dir_i, u32 *m_list, int m_count);
+
+int sqfs_read_metablock(unsigned char *file_mapping, int offset,
+                       bool *compressed, u32 *data_size);
+
+bool sqfs_is_empty_dir(void *dir_i);
+
+bool sqfs_is_dir(u16 type);
+
+#endif /* SQFS_FILESYSTEM_H */
diff --git a/fs/squashfs/sqfs_inode.c b/fs/squashfs/sqfs_inode.c
new file mode 100644 (file)
index 0000000..b037a9b
--- /dev/null
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#include <asm/unaligned.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "sqfs_decompressor.h"
+#include "sqfs_filesystem.h"
+#include "sqfs_utils.h"
+
+int sqfs_inode_size(struct squashfs_base_inode *inode, u32 blk_size)
+{
+       switch (get_unaligned_le16(&inode->inode_type)) {
+       case SQFS_DIR_TYPE:
+               return sizeof(struct squashfs_dir_inode);
+
+       case SQFS_REG_TYPE: {
+               struct squashfs_reg_inode *reg =
+                       (struct squashfs_reg_inode *)inode;
+               u32 fragment = get_unaligned_le32(&reg->fragment);
+               u32 file_size = get_unaligned_le32(&reg->file_size);
+               unsigned int blk_list_size;
+
+               if (SQFS_IS_FRAGMENTED(fragment))
+                       blk_list_size = file_size / blk_size;
+               else
+                       blk_list_size = DIV_ROUND_UP(file_size, blk_size);
+
+               return sizeof(*reg) + blk_list_size * sizeof(u32);
+       }
+
+       case SQFS_LDIR_TYPE: {
+               struct squashfs_ldir_inode *ldir =
+                       (struct squashfs_ldir_inode *)inode;
+               u16 i_count = get_unaligned_le16(&ldir->i_count);
+               unsigned int index_list_size = 0, l = 0;
+               struct squashfs_directory_index *di;
+               u32 sz;
+
+               if (i_count == 0)
+                       return sizeof(*ldir);
+
+               di = ldir->index;
+               while (l < i_count + 1) {
+                       sz = get_unaligned_le32(&di->size) + 1;
+                       index_list_size += sz;
+                       di = (void *)di + sizeof(*di) + sz;
+                       l++;
+               }
+
+               return sizeof(*ldir) + index_list_size +
+                       (i_count + 1) * SQFS_DIR_INDEX_BASE_LENGTH;
+       }
+
+       case SQFS_LREG_TYPE: {
+               struct squashfs_lreg_inode *lreg =
+                       (struct squashfs_lreg_inode *)inode;
+               u32 fragment = get_unaligned_le32(&lreg->fragment);
+               u64 file_size = get_unaligned_le64(&lreg->file_size);
+               unsigned int blk_list_size;
+
+               if (fragment == 0xFFFFFFFF)
+                       blk_list_size = DIV_ROUND_UP(file_size, blk_size);
+               else
+                       blk_list_size = file_size / blk_size;
+
+               return sizeof(*lreg) + blk_list_size * sizeof(u32);
+       }
+
+       case SQFS_SYMLINK_TYPE:
+       case SQFS_LSYMLINK_TYPE: {
+               struct squashfs_symlink_inode *symlink =
+                       (struct squashfs_symlink_inode *)inode;
+
+               return sizeof(*symlink) +
+                       get_unaligned_le32(&symlink->symlink_size);
+       }
+
+       case SQFS_BLKDEV_TYPE:
+       case SQFS_CHRDEV_TYPE:
+               return sizeof(struct squashfs_dev_inode);
+       case SQFS_LBLKDEV_TYPE:
+       case SQFS_LCHRDEV_TYPE:
+               return sizeof(struct squashfs_ldev_inode);
+       case SQFS_FIFO_TYPE:
+       case SQFS_SOCKET_TYPE:
+               return sizeof(struct squashfs_ipc_inode);
+       case SQFS_LFIFO_TYPE:
+       case SQFS_LSOCKET_TYPE:
+               return sizeof(struct squashfs_lipc_inode);
+       default:
+               printf("Error while searching inode: unknown type.\n");
+               return -EINVAL;
+       }
+}
+
+/*
+ * Given the uncompressed inode table, the inode to be found and the number of
+ * inodes in the table, return inode position in case of success.
+ */
+void *sqfs_find_inode(void *inode_table, int inode_number, __le32 inode_count,
+                     __le32 block_size)
+{
+       struct squashfs_base_inode *base;
+       unsigned int offset = 0, k;
+       int sz;
+
+       if (!inode_table) {
+               printf("%s: Invalid pointer to inode table.\n", __func__);
+               return NULL;
+       }
+
+       for (k = 0; k < le32_to_cpu(inode_count); k++) {
+               base = inode_table + offset;
+               if (get_unaligned_le32(&base->inode_number) == inode_number)
+                       return inode_table + offset;
+
+               sz = sqfs_inode_size(base, le32_to_cpu(block_size));
+               if (sz < 0)
+                       return NULL;
+
+               offset += sz;
+       }
+
+       printf("Inode not found.\n");
+
+       return NULL;
+}
+
+int sqfs_read_metablock(unsigned char *file_mapping, int offset,
+                       bool *compressed, u32 *data_size)
+{
+       unsigned char *data;
+       u16 header;
+
+       data = file_mapping + offset;
+       header = get_unaligned((u16 *)data);
+       *compressed = SQFS_COMPRESSED_METADATA(header);
+       *data_size = SQFS_METADATA_SIZE(header);
+
+       if (*data_size > SQFS_METADATA_BLOCK_SIZE) {
+               printf("Invalid metatada block size: %d bytes.\n", *data_size);
+               return -EINVAL;
+       }
+
+       return 0;
+}
diff --git a/fs/squashfs/sqfs_utils.h b/fs/squashfs/sqfs_utils.h
new file mode 100644 (file)
index 0000000..1260abe
--- /dev/null
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ */
+
+#ifndef SQFS_UTILS_H
+#define SQFS_UTILS_H
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <stdbool.h>
+
+#define SQFS_FRAGMENT_INDEX_OFFSET(A) ((A) % SQFS_MAX_ENTRIES)
+#define SQFS_FRAGMENT_INDEX(A) ((A) / SQFS_MAX_ENTRIES)
+#define SQFS_BLOCK_SIZE(A) ((A) & GENMASK(23, 0))
+#define SQFS_CHECK_FLAG(flag, bit) (((flag) >> (bit)) & 1)
+/* Useful for both fragment and data blocks */
+#define SQFS_COMPRESSED_BLOCK(A) (!((A) & BIT(24)))
+/* SQFS_COMPRESSED_DATA strictly used with super block's 'flags' member */
+#define SQFS_COMPRESSED_DATA(A) (!((A) & 0x0002))
+#define SQFS_IS_FRAGMENTED(A) ((A) != 0xFFFFFFFF)
+/*
+ * These two macros work as getters for a metada block header, retrieving the
+ * data size and if it is compressed/uncompressed
+ */
+#define SQFS_COMPRESSED_METADATA(A) (!((A) & BIT(15)))
+#define SQFS_METADATA_SIZE(A) ((A) & GENMASK(14, 0))
+
+struct squashfs_super_block_flags {
+       /* check: unused
+        * uncompressed_ids: not supported
+        */
+       bool uncompressed_inodes;
+       bool uncompressed_data;
+       bool check;
+       bool uncompressed_frags;
+       bool no_frags;
+       bool always_frags;
+       bool duplicates;
+       bool exportable;
+       bool uncompressed_xattrs;
+       bool no_xattrs;
+       bool compressor_options;
+       bool uncompressed_ids;
+};
+
+#endif /* SQFS_UTILS_H  */
index b08b1f4..0794b50 100644 (file)
@@ -15,6 +15,7 @@ struct cmd_tbl;
 #define FS_TYPE_SANDBOX        3
 #define FS_TYPE_UBIFS  4
 #define FS_TYPE_BTRFS  5
+#define FS_TYPE_SQUASHFS 6
 
 struct blk_desc;
 
diff --git a/include/squashfs.h b/include/squashfs.h
new file mode 100644 (file)
index 0000000..819cf8c
--- /dev/null
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2020 Bootlin
+ *
+ * Author: Joao Marcos Costa <joaomarcos.costa@bootlin.com>
+ *
+ * squashfs.h: SquashFS filesystem implementation.
+ */
+
+#ifndef _SQFS_H_
+#define _SQFS_H_
+
+struct disk_partition;
+
+int sqfs_opendir(const char *filename, struct fs_dir_stream **dirsp);
+int sqfs_readdir(struct fs_dir_stream *dirs, struct fs_dirent **dentp);
+int sqfs_probe(struct blk_desc *fs_dev_desc,
+              struct disk_partition *fs_partition);
+int sqfs_read(const char *filename, void *buf, loff_t offset,
+             loff_t len, loff_t *actread);
+int sqfs_size(const char *filename, loff_t *size);
+void sqfs_close(void);
+void sqfs_closedir(struct fs_dir_stream *dirs);
+
+#endif /* SQFS_H  */