ext2: add support to various inode sizes

the script used for generating test inputs:

    declare -A sizes=(
	[1024,1024]=$((130048 + 1024))
	[2048,512]=$((  45056 + 2048))
	[4096,128]=$((  53248 + 4096))
    )

    adjust_size()
    {
	local f=$1
	local bsize=$2
	local isize=$3

	truncate --size=${sizes[$bsize,$isize]} $f
    }

    makeimg()
    {
	local bsize=$1
	local isize=$2

	local f=tests/files/bsize-${bsize}-isize-${isize}.ext2
	dd if=/dev/zero of=$f bs=${bsize} count=128
	mkfs.ext2 -I ${isize} -b ${bsize} $f
	sudo mount $f __tmp__
	echo hello | sudo dd if=/dev/stdin of=__tmp__/source
	(cd __tmp__/; sudo ln -s source target)
	sudo umount __tmp__
	adjust_size $f $bsize $isize
    }

    mkdir -p __tmp__
    makeimg 1024 1024
    makeimg 2048 512
    makeimg 4096 128
    rmdir __tmp__

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

hachoir/parser/file_system/ext2.py

@@ -201,10 +201,13 @@ class Inode(FieldSet):
         7: "Reserved group descriptors",
         8: "EXT3 journal"
     }
-    static_size = (68 + 15 * 4) * 8
 
     def __init__(self, parent, name, index):
         FieldSet.__init__(self, parent, name, None)
+        inode_size = self["/superblock/inode_size"].value
+        if inode_size == 0:
+            inode_size = 128
+        self._size = inode_size * 8
         self.uniq_id = 1 + index
 
     def createDescription(self):
@@ -751,7 +754,10 @@ def validate(self):
             return "Invalid magic number"
         if not (0 <= self["superblock/log_block_size"].value <= 2):
             return "Invalid (log) block size"
-        if self["superblock/inode_size"].value not in (0, 128):
+        blocksize = (1 << 10) << self["superblock/log_block_size"].value
+        acceptable_inode_sizes = (s for s in [0, 128, 256, 512, 1024, 2048, 4096]
+                                  if s <= blocksize)
+        if self["superblock/inode_size"].value not in acceptable_inode_sizes:
             return "Unsupported inode size"
         return True
 

tests/test_parser.py

@@ -348,6 +348,16 @@ def test_ext2_variety_inode_types(self):
         self.checkDesc(parser, "/group[0]/inode_table/inode[12]",
                        "Inode 13: Symbolic link (-> XYZ), size=3 bytes, mode=lrwxrwxrwx")
 
+    def test_ext2_various_inode_sizes(self):
+        for bsize, isize in [(1024, 1024), (2048, 512), (4096, 128)]:
+            fname = "bsize-%d-isize-%d.ext2" % (bsize, isize)
+            parser = self.parse(fname)
+            self.checkValue(parser, "/superblock/inode_size", isize)
+            self.checkValue(parser, "/group[0]/inode_table/inode[11]/size", 6)
+            self.checkDesc(parser, "/group[0]/inode_table/inode[12]",
+                           "Inode 13: Symbolic link (-> source), size=6 bytes, mode=lrwxrwxrwx")
+            self.checkValue(parser, "/group[0]/inode[11]block[0]", b"hello\n" + b'\0' * (bsize - 6))
+
     def test_bmp2(self):
         parser = self.parse("article01.bmp")
         self.checkDisplay(parser, "/header/red_mask", '0x00ff0000')