Added conversion to/from little-endian on disk

Required to support big-endian processors, with the most notable being the PowerPC architecture. On little-endian architectures, these conversions can be optimized out and have no code impact. Initial patch provided by gmouchard
Added conversion to/from little endian on disk
2025-11-01 16:14:13 +01:00 · 2018-02-15 16:33:03 -06:00 · 2018-02-04 11:51:23 -06:00
15 changed files with 240 additions and 309 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +0,0 @@
-# Compilation output
-*.o
-*.d
-*.a
-
-# Testing things
-blocks/
-lfs
-test.c
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,23 +1,20 @@
-env:
-    - CFLAGS=-Werror
-
 script:
    # make sure example can at least compile
    - sed -n '/``` c/,/```/{/```/d; p;}' README.md > test.c &&
-      make all size CFLAGS+="
+      CFLAGS='
        -Duser_provided_block_device_read=NULL
        -Duser_provided_block_device_prog=NULL
        -Duser_provided_block_device_erase=NULL
        -Duser_provided_block_device_sync=NULL
-        -include stdio.h"
+        -include stdio.h -Werror' make all size

    # run tests
    - make test QUIET=1

    # run tests with a few different configurations
-    - make test QUIET=1 CFLAGS+="-DLFS_READ_SIZE=1      -DLFS_PROG_SIZE=1"
-    - make test QUIET=1 CFLAGS+="-DLFS_READ_SIZE=512    -DLFS_PROG_SIZE=512"
-    - make test QUIET=1 CFLAGS+="-DLFS_BLOCK_COUNT=1023 -DLFS_LOOKAHEAD=2048"
+    - CFLAGS="-DLFS_READ_SIZE=1   -DLFS_PROG_SIZE=1"       make test QUIET=1
+    - CFLAGS="-DLFS_READ_SIZE=512 -DLFS_PROG_SIZE=512"     make test QUIET=1
+    - CFLAGS="-DLFS_BLOCK_COUNT=1023 -DLFS_LOOKAHEAD=2048" make test QUIET=1

    # self-host with littlefs-fuse for fuzz test
    - make -C littlefs-fuse
@@ -48,60 +45,3 @@ before_script:
    - sudo chmod a+rw /dev/loop0
    - dd if=/dev/zero bs=512 count=2048 of=disk
    - losetup /dev/loop0 disk
-
-deploy:
-    # Let before_deploy take over
-    provider: script
-    script: 'true'
-    on:
-        branch: master
-
-before_deploy:
-    - cd $TRAVIS_BUILD_DIR
-    # Update tag for version defined in lfs.h
-    - LFS_VERSION=$(grep -ox '#define LFS_VERSION .*' lfs.h | cut -d ' ' -f3)
-    - LFS_VERSION_MAJOR=$((0xffff & ($LFS_VERSION >> 16)))
-    - LFS_VERSION_MINOR=$((0xffff & ($LFS_VERSION >>  0)))
-    - LFS_VERSION="v$LFS_VERSION_MAJOR.$LFS_VERSION_MINOR"
-    - echo "littlefs version $LFS_VERSION"
-    - |
-      curl -u $GEKY_BOT -X POST \
-        https://api.github.com/repos/$TRAVIS_REPO_SLUG/git/refs \
-        -d "{
-          \"ref\": \"refs/tags/$LFS_VERSION\",
-          \"sha\": \"$TRAVIS_COMMIT\"
-        }"
-    - |
-      curl -f -u $GEKY_BOT -X PATCH \
-        https://api.github.com/repos/$TRAVIS_REPO_SLUG/git/refs/tags/$LFS_VERSION \
-        -d "{
-          \"sha\": \"$TRAVIS_COMMIT\"
-        }"
-    # Create release notes from commits
-    - LFS_PREV_VERSION="v$LFS_VERSION_MAJOR.$(($LFS_VERSION_MINOR-1))"
-    - |
-      if [ $(git tag -l "$LFS_PREV_VERSION") ]
-      then
-        curl -u $GEKY_BOT -X POST \
-            https://api.github.com/repos/$TRAVIS_REPO_SLUG/releases \
-            -d "{
-                \"tag_name\": \"$LFS_VERSION\",
-                \"name\": \"$LFS_VERSION\"
-            }"
-        RELEASE=$(
-            curl -f https://api.github.com/repos/$TRAVIS_REPO_SLUG/releases/tags/$LFS_VERSION
-        )
-        CHANGES=$(
-            git log --oneline $LFS_PREV_VERSION.. --grep='^Merge' --invert-grep
-        )
-        curl -f -u $GEKY_BOT -X PATCH \
-            https://api.github.com/repos/$TRAVIS_REPO_SLUG/releases/$(
-                jq -r '.id' <<< "$RELEASE"
-            ) \
-            -d "$(
-                jq -s '{
-                    "body": ((.[0] // "" | sub("(?<=\n)#+ Changes.*"; ""; "mi"))
-                        + "### Changes\n\n" + .[1])
-                }' <(jq '.body' <<< "$RELEASE") <(jq -sR '.' <<< "$CHANGES")
-            )"
-      fi
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -27,17 +27,16 @@ cheap, and can be very granular. For NOR flash specifically, byte-level
 programs are quite common. Erasing, however, requires an expensive operation
 that forces the state of large blocks of memory to reset in a destructive
 reaction that gives flash its name. The [Wikipedia entry](https://en.wikipedia.org/wiki/Flash_memory)
-has more information if you are interested in how this works.
+has more information if you are interesting in how this works.

 This leaves us with an interesting set of limitations that can be simplified
 to three strong requirements:

 1. **Power-loss resilient** - This is the main goal of the littlefs and the
-   focus of this project.
-
-   Embedded systems are usually designed without a shutdown routine and a
-   notable lack of user interface for recovery, so filesystems targeting
-   embedded systems must be prepared to lose power at any given time.
+   focus of this project. Embedded systems are usually designed without a
+   shutdown routine and a notable lack of user interface for recovery, so
+   filesystems targeting embedded systems must be prepared to lose power an
+   any given time.

   Despite this state of things, there are very few embedded filesystems that
   handle power loss in a reasonable manner, and most can become corrupted if
@@ -53,8 +52,7 @@ to three strong requirements:
   which stores a file allocation table (FAT) at a specific offset from the
   beginning of disk. Every block allocation will update this table, and after
   100,000 updates, the block will likely go bad, rendering the filesystem
-   unusable even if there are many more erase cycles available on the storage
-   as a whole.
+   unusable even if there are many more erase cycles available on the storage.

 3. **Bounded RAM/ROM** - Even with the design difficulties presented by the
   previous two limitations, we have already seen several flash filesystems
@@ -74,7 +72,7 @@ to three strong requirements:

 ## Existing designs?

-There are of course, many different existing filesystem. Here is a very rough
+There are of course, many different existing filesystem. Heres a very rough
 summary of the general ideas behind some of them.

 Most of the existing filesystems fall into the one big category of filesystem
@@ -82,21 +80,21 @@ designed in the early days of spinny magnet disks. While there is a vast amount
 of interesting technology and ideas in this area, the nature of spinny magnet
 disks encourage properties, such as grouping writes near each other, that don't
 make as much sense on recent storage types. For instance, on flash, write
-locality is not important and can actually increase wear.
+locality is not important and can actually increase wear destructively.

 One of the most popular designs for flash filesystems is called the
 [logging filesystem](https://en.wikipedia.org/wiki/Log-structured_file_system).
 The flash filesystems [jffs](https://en.wikipedia.org/wiki/JFFS)
-and [yaffs](https://en.wikipedia.org/wiki/YAFFS) are good examples. In a
-logging filesystem, data is not stored in a data structure on disk, but instead
+and [yaffs](https://en.wikipedia.org/wiki/YAFFS) are good examples. In
+logging filesystem, data is not store in a data structure on disk, but instead
 the changes to the files are stored on disk. This has several neat advantages,
-such as the fact that the data is written in a cyclic log format and naturally
+such as the fact that the data is written in a cyclic log format naturally
 wear levels as a side effect. And, with a bit of error detection, the entire
 filesystem can easily be designed to be resilient to power loss. The
-journaling component of most modern day filesystems is actually a reduced
+journalling component of most modern day filesystems is actually a reduced
 form of a logging filesystem. However, logging filesystems have a difficulty
 scaling as the size of storage increases. And most filesystems compensate by
-caching large parts of the filesystem in RAM, a strategy that is inappropriate
+caching large parts of the filesystem in RAM, a strategy that is unavailable
 for embedded systems.

 Another interesting filesystem design technique is that of [copy-on-write (COW)](https://en.wikipedia.org/wiki/Copy-on-write).
@@ -109,14 +107,14 @@ where the COW data structures are synchronized.
 ## Metadata pairs

 The core piece of technology that provides the backbone for the littlefs is
-the concept of metadata pairs. The key idea here is that any metadata that
+the concept of metadata pairs. The key idea here, is that any metadata that
 needs to be updated atomically is stored on a pair of blocks tagged with
 a revision count and checksum. Every update alternates between these two
 pairs, so that at any time there is always a backup containing the previous
 state of the metadata.

 Consider a small example where each metadata pair has a revision count,
-a number as data, and the XOR of the block as a quick checksum. If
+a number as data, and the xor of the block as a quick checksum. If
 we update the data to a value of 9, and then to a value of 5, here is
 what the pair of blocks may look like after each update:
 ```
@@ -132,7 +130,7 @@ what the pair of blocks may look like after each update:
 After each update, we can find the most up to date value of data by looking
 at the revision count.

-Now consider what the blocks may look like if we suddenly lose power while
+Now consider what the blocks may look like if we suddenly loss power while
 changing the value of data to 5:
 ```
  block 1   block 2        block 1   block 2        block 1   block 2
@@ -151,7 +149,7 @@ check our checksum we notice that block 1 was corrupted. So we fall back to
 block 2 and use the value 9.

 Using this concept, the littlefs is able to update metadata blocks atomically.
-There are a few other tweaks, such as using a 32 bit CRC and using sequence
+There are a few other tweaks, such as using a 32 bit crc and using sequence
 arithmetic to handle revision count overflow, but the basic concept
 is the same. These metadata pairs define the backbone of the littlefs, and the
 rest of the filesystem is built on top of these atomic updates.
@@ -163,7 +161,7 @@ requires two blocks for each block of data. I'm sure users would be very
 unhappy if their storage was suddenly cut in half! Instead of storing
 everything in these metadata blocks, the littlefs uses a COW data structure
 for files which is in turn pointed to by a metadata block. When
-we update a file, we create copies of any blocks that are modified until
+we update a file, we create a copies of any blocks that are modified until
 the metadata blocks are updated with the new copy. Once the metadata block
 points to the new copy, we deallocate the old blocks that are no longer in use.

@@ -186,7 +184,7 @@ Here is what updating a one-block file may look like:
            update data in file        update metadata pair
 ```

-It doesn't matter if we lose power while writing new data to block 5,
+It doesn't matter if we lose power while writing block 5 with the new data,
 since the old data remains unmodified in block 4. This example also
 highlights how the atomic updates of the metadata blocks provide a
 synchronization barrier for the rest of the littlefs.
@@ -208,7 +206,7 @@ files in filesystems. Of these, the littlefs uses a rather unique [COW](https://
 data structure that allows the filesystem to reuse unmodified parts of the
 file without additional metadata pairs.

-First lets consider storing files in a simple linked-list. What happens when we
+First lets consider storing files in a simple linked-list. What happens when
 append a block? We have to change the last block in the linked-list to point
 to this new block, which means we have to copy out the last block, and change
 the second-to-last block, and then the third-to-last, and so on until we've
@@ -242,8 +240,8 @@ Exhibit B: A backwards linked-list
 ```

 However, a backwards linked-list does come with a rather glaring problem.
-Iterating over a file _in order_ has a runtime cost of O(n^2). Gah! A quadratic
-runtime to just _read_ a file? That's awful. Keep in mind reading files is
+Iterating over a file _in order_ has a runtime of O(n^2). Gah! A quadratic
+runtime to just _read_ a file? That's awful. Keep in mind reading files are
 usually the most common filesystem operation.

 To avoid this problem, the littlefs uses a multilayered linked-list. For
@@ -268,7 +266,7 @@ Exhibit C: A backwards CTZ skip-list
 ```

 The additional pointers allow us to navigate the data-structure on disk
-much more efficiently than in a singly linked-list.
+much more efficiently than in a single linked-list.

 Taking exhibit C for example, here is the path from data block 5 to data
 block 1. You can see how data block 3 was completely skipped:
@@ -291,15 +289,15 @@ The path to data block 0 is even more quick, requiring only two jumps:

 We can find the runtime complexity by looking at the path to any block from
 the block containing the most pointers. Every step along the path divides
-the search space for the block in half. This gives us a runtime of O(log n).
+the search space for the block in half. This gives us a runtime of O(logn).
 To get to the block with the most pointers, we can perform the same steps
-backwards, which puts the runtime at O(2 log n) = O(log n). The interesting
+backwards, which puts the runtime at O(2logn) = O(logn). The interesting
 part about this data structure is that this optimal path occurs naturally
 if we greedily choose the pointer that covers the most distance without passing
 our target block.

 So now we have a representation of files that can be appended trivially with
-a runtime of O(1), and can be read with a worst case runtime of O(n log n).
+a runtime of O(1), and can be read with a worst case runtime of O(nlogn).
 Given that the the runtime is also divided by the amount of data we can store
 in a block, this is pretty reasonable.

@@ -364,7 +362,7 @@ N = file size in bytes

 And this works quite well, but is not trivial to calculate. This equation
 requires O(n) to compute, which brings the entire runtime of reading a file
-to O(n^2 log n). Fortunately, the additional O(n) does not need to touch disk,
+to O(n^2logn). Fortunately, the additional O(n) does not need to touch disk,
 so it is not completely unreasonable. But if we could solve this equation into
 a form that is easily computable, we can avoid a big slowdown.

@@ -381,11 +379,11 @@ unintuitive property:
 ![mindblown](https://latex.codecogs.com/svg.latex?%5Csum_i%5En%5Cleft%28%5Ctext%7Bctz%7D%28i%29&plus;1%5Cright%29%20%3D%202n-%5Ctext%7Bpopcount%7D%28n%29)

 where:  
-ctz(x) = the number of trailing bits that are 0 in x  
-popcount(x) = the number of bits that are 1 in x  
+ctz(i) = the number of trailing bits that are 0 in i  
+popcount(i) = the number of bits that are 1 in i  

 It's a bit bewildering that these two seemingly unrelated bitwise instructions
-are related by this property. But if we start to dissect this equation we can
+are related by this property. But if we start to disect this equation we can
 see that it does hold. As n approaches infinity, we do end up with an average
 overhead of 2 pointers as we find earlier. And popcount seems to handle the
 error from this average as it accumulates in the CTZ skip-list.
@@ -412,7 +410,8 @@ a bit to avoid integer overflow:
 ![formulaforoff](https://latex.codecogs.com/svg.latex?%5Cmathit%7Boff%7D%20%3D%20N%20-%20%5Cleft%28B-2%5Cfrac%7Bw%7D%7B8%7D%5Cright%29n%20-%20%5Cfrac%7Bw%7D%7B8%7D%5Ctext%7Bpopcount%7D%28n%29)

 The solution involves quite a bit of math, but computers are very good at math.
-Now we can solve for both the block index and offset from the file size in O(1).
+We can now solve for the block index + offset while only needed to store the
+file size in O(1).

 Here is what it might look like to update a file stored with a CTZ skip-list:
 ```
@@ -501,17 +500,16 @@ scanned to find the most recent free list, but once the list was found the
 state of all free blocks becomes known.

 However, this approach had several issues:
-
 - There was a lot of nuanced logic for adding blocks to the free list without
  modifying the blocks, since the blocks remain active until the metadata is
  updated.
- The free list had to support both additions and removals in FIFO order while
+- The free list had to support both additions and removals in fifo order while
  minimizing block erases.
 - The free list had to handle the case where the file system completely ran
  out of blocks and may no longer be able to add blocks to the free list.
 - If we used a revision count to track the most recently updated free list,
  metadata blocks that were left unmodified were ticking time bombs that would
-  cause the system to go haywire if the revision count overflowed.
+  cause the system to go haywire if the revision count overflowed
 - Every single metadata block wasted space to store these free list references.

 Actually, to simplify, this approach had one massive glaring issue: complexity.
@@ -541,7 +539,7 @@ would have an abhorrent runtime.
 So the littlefs compromises. It doesn't store a bitmap the size of the storage,
 but it does store a little bit-vector that contains a fixed set lookahead
 for block allocations. During a block allocation, the lookahead vector is
-checked for any free blocks. If there are none, the lookahead region jumps
+checked for any free blocks, if there are none, the lookahead region jumps
 forward and the entire filesystem is scanned for free blocks.

 Here's what it might look like to allocate 4 blocks on a decently busy
@@ -624,7 +622,7 @@ So, as a solution, the littlefs adopted a sort of threaded tree. Each
 directory not only contains pointers to all of its children, but also a
 pointer to the next directory. These pointers create a linked-list that
 is threaded through all of the directories in the filesystem. Since we
-only use this linked list to check for existence, the order doesn't actually
+only use this linked list to check for existance, the order doesn't actually
 matter. As an added plus, we can repurpose the pointer for the individual
 directory linked-lists and avoid using any additional space.

@@ -775,7 +773,7 @@ deorphan step that simply iterates through every directory in the linked-list
 and checks it against every directory entry in the filesystem to see if it
 has a parent. The deorphan step occurs on the first block allocation after
 boot, so orphans should never cause the littlefs to run out of storage
-prematurely. Note that the deorphan step never needs to run in a read-only
+prematurely. Note that the deorphan step never needs to run in a readonly
 filesystem.

 ## The move problem
@@ -885,7 +883,7 @@ a power loss will occur during filesystem activity. We still need to handle
 the condition, but runtime during a power loss takes a back seat to the runtime
 during normal operations.

-So what littlefs does is inelegantly simple. When littlefs moves a file, it
+So what littlefs does is unelegantly simple. When littlefs moves a file, it
 marks the file as "moving". This is stored as a single bit in the directory
 entry and doesn't take up much space. Then littlefs moves the directory,
 finishing with the complete remove of the "moving" directory entry.
@@ -981,7 +979,7 @@ if it exists elsewhere in the filesystem.
 So now that we have all of the pieces of a filesystem, we can look at a more
 subtle attribute of embedded storage: The wear down of flash blocks.

-The first concern for the littlefs, is that perfectly valid blocks can suddenly
+The first concern for the littlefs, is that prefectly valid blocks can suddenly
 become unusable. As a nice side-effect of using a COW data-structure for files,
 we can simply move on to a different block when a file write fails. All
 modifications to files are performed in copies, so we will only replace the
@@ -1153,7 +1151,7 @@ develops errors and needs to be moved.

 ## Wear leveling

-The second concern for the littlefs is that blocks in the filesystem may wear
+The second concern for the littlefs, is that blocks in the filesystem may wear
 unevenly. In this situation, a filesystem may meet an early demise where
 there are no more non-corrupted blocks that aren't in use. It's common to
 have files that were written once and left unmodified, wasting the potential
@@ -1173,7 +1171,7 @@ of wear leveling:

 In littlefs's case, it's possible to use the revision count on metadata pairs
 to approximate the wear of a metadata block. And combined with the COW nature
-of files, littlefs could provide your usual implementation of dynamic wear
+of files, littlefs could provide your usually implementation of dynamic wear
 leveling.

 However, the littlefs does not. This is for a few reasons. Most notably, even
@@ -1212,9 +1210,9 @@ So, to summarize:
   metadata block is active
 4. Directory blocks contain either references to other directories or files
 5. Files are represented by copy-on-write CTZ skip-lists which support O(1)
-   append and O(n log n) reading
+   append and O(nlogn) reading
 6. Blocks are allocated by scanning the filesystem for used blocks in a
-   fixed-size lookahead region that is stored in a bit-vector
+   fixed-size lookahead region is that stored in a bit-vector
 7. To facilitate scanning the filesystem, all directories are part of a
   linked-list that is threaded through the entire filesystem
 8. If a block develops an error, the littlefs allocates a new block, and
--- a/12
+++ b/12
@@ -14,15 +14,15 @@ TEST := $(patsubst tests/%.sh,%,$(wildcard tests/test_*))
 SHELL = /bin/bash -o pipefail

 ifdef DEBUG
-override CFLAGS += -O0 -g3
+CFLAGS += -O0 -g3
 else
-override CFLAGS += -Os
+CFLAGS += -Os
 endif
 ifdef WORD
-override CFLAGS += -m$(WORD)
+CFLAGS += -m$(WORD)
 endif
-override CFLAGS += -I.
-override CFLAGS += -std=c99 -Wall -pedantic
+CFLAGS += -I.
+CFLAGS += -std=c99 -Wall -pedantic


 all: $(TARGET)
@@ -37,7 +37,7 @@ test: test_format test_dirs test_files test_seek test_truncate test_parallel \
 	test_alloc test_paths test_orphan test_move test_corrupt
 test_%: tests/test_%.sh
 ifdef QUIET
-	@./$< | sed -n '/^[-=]/p'
+	./$< | sed -n '/^[-=]/p'
 else
 	./$<
 endif
--- a/README.md
+++ b/README.md
@@ -16,7 +16,7 @@ of memory. Recursion is avoided and dynamic memory is limited to configurable
 buffers that can be provided statically.

 **Power-loss resilient** - The littlefs is designed for systems that may have
-random power failures. The littlefs has strong copy-on-write guarantees and
+random power failures. The littlefs has strong copy-on-write guaruntees and
 storage on disk is always kept in a valid state.

 **Wear leveling** - Since the most common form of embedded storage is erodible
@@ -88,7 +88,7 @@ int main(void) {
 ## Usage

 Detailed documentation (or at least as much detail as is currently available)
-can be found in the comments in [lfs.h](lfs.h).
+can be cound in the comments in [lfs.h](lfs.h).

 As you may have noticed, littlefs takes in a configuration structure that
 defines how the filesystem operates. The configuration struct provides the
@@ -101,12 +101,12 @@ to the user to allocate, allowing multiple filesystems to be in use
 simultaneously. With the `lfs_t` and configuration struct, a user can
 format a block device or mount the filesystem.

-Once mounted, the littlefs provides a full set of POSIX-like file and
+Once mounted, the littlefs provides a full set of posix-like file and
 directory functions, with the deviation that the allocation of filesystem
 structures must be provided by the user.

-All POSIX operations, such as remove and rename, are atomic, even in event
-of power-loss. Additionally, no file updates are actually committed to the
+All posix operations, such as remove and rename, are atomic, even in event
+of power-loss. Additionally, no file updates are actually commited to the
 filesystem until sync or close is called on the file.

 ## Other notes
@@ -116,7 +116,7 @@ can be either one of those found in the `enum lfs_error` in [lfs.h](lfs.h),
 or an error returned by the user's block device operations.

 It should also be noted that the current implementation of littlefs doesn't
-really do anything to ensure that the data written to disk is machine portable.
+really do anything to insure that the data written to disk is machine portable.
 This is fine as long as all of the involved machines share endianness
 (little-endian) and don't have strange padding requirements.

@@ -131,9 +131,9 @@ with all the nitty-gritty details. Can be useful for developing tooling.

 ## Testing

-The littlefs comes with a test suite designed to run on a PC using the
+The littlefs comes with a test suite designed to run on a pc using the
 [emulated block device](emubd/lfs_emubd.h) found in the emubd directory.
-The tests assume a Linux environment and can be started with make:
+The tests assume a linux environment and can be started with make:

 ``` bash
 make test
@@ -148,7 +148,7 @@ littlefs is available in Mbed OS as the [LittleFileSystem](https://os.mbed.com/d
 class.

 [littlefs-fuse](https://github.com/geky/littlefs-fuse) - A [FUSE](https://github.com/libfuse/libfuse)
-wrapper for littlefs. The project allows you to mount littlefs directly on a
+wrapper for littlefs. The project allows you to mount littlefs directly in a
 Linux machine. Can be useful for debugging littlefs if you have an SD card
 handy.

--- a/SPEC.md
+++ b/SPEC.md
@@ -46,7 +46,7 @@ Here's the layout of metadata blocks on disk:
 | 0x04   | 32 bits       | dir size       |
 | 0x08   | 64 bits       | tail pointer   |
 | 0x10   | size-16 bytes | dir entries    |
-| 0x00+s | 32 bits       | CRC            |
+| 0x00+s | 32 bits       | crc            |

 **Revision count** - Incremented every update, only the uncorrupted
 metadata-block with the most recent revision count contains the valid metadata.
@@ -75,7 +75,7 @@ Here's an example of a simple directory stored on disk:
 (32 bits) revision count = 10                    (0x0000000a)
 (32 bits) dir size       = 154 bytes, end of dir (0x0000009a)
 (64 bits) tail pointer   = 37, 36                (0x00000025, 0x00000024)
-(32 bits) CRC            = 0xc86e3106
+(32 bits) crc            = 0xc86e3106

 00000000: 0a 00 00 00 9a 00 00 00 25 00 00 00 24 00 00 00  ........%...$...
 00000010: 22 08 00 03 05 00 00 00 04 00 00 00 74 65 61 22  "...........tea"
@@ -138,12 +138,12 @@ not include the entry type size, attributes, or name. The full size in bytes
 of the entry is 4 + entry length + attribute length + name length.

 **Attribute length** - Length of system-specific attributes in bytes. Since
-attributes are system specific, there is not much guarantee on the values in
+attributes are system specific, there is not much garuntee on the values in
 this section, and systems are expected to work even when it is empty. See the
 [attributes](#entry-attributes) section for more details.

-**Name length** - Length of the entry name. Entry names are stored as UTF8,
-although most systems will probably only support ASCII. Entry names can not
+**Name length** - Length of the entry name. Entry names are stored as utf8,
+although most systems will probably only support ascii. Entry names can not
 contain '/' and can not be '.' or '..' as these are a part of the syntax of
 filesystem paths.

@@ -222,7 +222,7 @@ Here's an example of a complete superblock:
 (32 bits) block count      = 1024 blocks          (0x00000400)
 (32 bits) version          = 1.1                  (0x00010001)
 (8 bytes) magic string     = littlefs
-(32 bits) CRC              = 0xc50b74fa
+(32 bits) crc              = 0xc50b74fa

 00000000: 03 00 00 00 34 00 00 00 03 00 00 00 02 00 00 00  ....4...........
 00000010: 2e 14 00 08 03 00 00 00 02 00 00 00 00 02 00 00  ................
--- a/emubd/lfs_emubd.c
+++ b/emubd/lfs_emubd.c
@@ -190,13 +190,13 @@ int lfs_emubd_erase(const struct lfs_config *cfg, lfs_block_t block) {
    }

    if (!err && S_ISREG(st.st_mode) && (S_IWUSR & st.st_mode)) {
-        err = unlink(emu->path);
+        int err = unlink(emu->path);
        if (err) {
            return -errno;
        }
    }

-    if (err || (S_ISREG(st.st_mode) && (S_IWUSR & st.st_mode))) {
+    if (errno == ENOENT || (S_ISREG(st.st_mode) && (S_IWUSR & st.st_mode))) {
        FILE *f = fopen(emu->path, "w");
        if (!f) {
            return -errno;
--- a/lfs.c
+++ b/lfs.c
@@ -278,7 +278,7 @@ static int lfs_alloc_lookahead(void *p, lfs_block_t block) {
                % (lfs_soff_t)(lfs->cfg->block_count))
            + lfs->cfg->block_count) % lfs->cfg->block_count;

-    if (off < lfs->free.size) {
+    if (off < lfs->cfg->lookahead) {
        lfs->free.buffer[off / 32] |= 1U << (off % 32);
    }

@@ -287,7 +287,18 @@ static int lfs_alloc_lookahead(void *p, lfs_block_t block) {

 static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
    while (true) {
-        while (lfs->free.off != lfs->free.size) {
+        while (true) {
+            // check if we have looked at all blocks since last ack
+            if (lfs->free.begin + lfs->free.off == lfs->free.end) {
+                LFS_WARN("No more free space %d", lfs->free.end);
+                return LFS_ERR_NOSPC;
+            }
+
+            if (lfs->free.off >= lfs_min(
+                    lfs->cfg->lookahead, lfs->cfg->block_count)) {
+                break;
+            }
+
            lfs_block_t off = lfs->free.off;
            lfs->free.off += 1;

@@ -298,15 +309,7 @@ static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
            }
        }

-        // check if we have looked at all blocks since last ack
-        if (lfs->free.off == lfs->free.ack - lfs->free.begin) {
-            LFS_WARN("No more free space %d", lfs->free.off + lfs->free.begin);
-            return LFS_ERR_NOSPC;
-        }
-
-        lfs->free.begin += lfs->free.size;
-        lfs->free.size = lfs_min(lfs->cfg->lookahead,
-                lfs->free.ack - lfs->free.begin);
+        lfs->free.begin += lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
        lfs->free.off = 0;

        // find mask of free blocks from tree
@@ -319,7 +322,49 @@ static int lfs_alloc(lfs_t *lfs, lfs_block_t *block) {
 }

 static void lfs_alloc_ack(lfs_t *lfs) {
-    lfs->free.ack = lfs->free.off-1 + lfs->free.begin + lfs->cfg->block_count;
+    lfs->free.end = lfs->free.begin + lfs->free.off + lfs->cfg->block_count;
+}
+
+
+/// Endian swapping functions ///
+static void lfs_dir_fromle32(struct lfs_disk_dir *d) {
+    d->rev     = lfs_fromle32(d->rev);
+    d->size    = lfs_fromle32(d->size);
+    d->tail[0] = lfs_fromle32(d->tail[0]);
+    d->tail[1] = lfs_fromle32(d->tail[1]);
+}
+
+static void lfs_dir_tole32(struct lfs_disk_dir *d) {
+    d->rev     = lfs_tole32(d->rev);
+    d->size    = lfs_tole32(d->size);
+    d->tail[0] = lfs_tole32(d->tail[0]);
+    d->tail[1] = lfs_tole32(d->tail[1]);
+}
+
+static void lfs_entry_fromle32(struct lfs_disk_entry *d) {
+    d->u.dir[0] = lfs_fromle32(d->u.dir[0]);
+    d->u.dir[1] = lfs_fromle32(d->u.dir[1]);
+}
+
+static void lfs_entry_tole32(struct lfs_disk_entry *d) {
+    d->u.dir[0] = lfs_tole32(d->u.dir[0]);
+    d->u.dir[1] = lfs_tole32(d->u.dir[1]);
+}
+
+static void lfs_superblock_fromle32(struct lfs_disk_superblock *d) {
+    d->root[0]     = lfs_fromle32(d->root[0]);
+    d->root[1]     = lfs_fromle32(d->root[1]);
+    d->block_size  = lfs_fromle32(d->block_size);
+    d->block_count = lfs_fromle32(d->block_count);
+    d->version     = lfs_fromle32(d->version);
+}
+
+static void lfs_superblock_tole32(struct lfs_disk_superblock *d) {
+    d->root[0]     = lfs_tole32(d->root[0]);
+    d->root[1]     = lfs_tole32(d->root[1]);
+    d->block_size  = lfs_tole32(d->block_size);
+    d->block_count = lfs_tole32(d->block_count);
+    d->version     = lfs_tole32(d->version);
 }


@@ -364,6 +409,7 @@ static int lfs_dir_alloc(lfs_t *lfs, lfs_dir_t *dir) {
    // rather than clobbering one of the blocks we just pretend
    // the revision may be valid
    int err = lfs_bd_read(lfs, dir->pair[0], 0, &dir->d.rev, 4);
+    dir->d.rev = lfs_fromle32(dir->d.rev);
    if (err) {
        return err;
    }
@@ -389,6 +435,7 @@ static int lfs_dir_fetch(lfs_t *lfs,
    for (int i = 0; i < 2; i++) {
        struct lfs_disk_dir test;
        int err = lfs_bd_read(lfs, tpair[i], 0, &test, sizeof(test));
+        lfs_dir_fromle32(&test);
        if (err) {
            return err;
        }
@@ -403,7 +450,9 @@ static int lfs_dir_fetch(lfs_t *lfs,
        }

        uint32_t crc = 0xffffffff;
+        lfs_dir_tole32(&test);
        lfs_crc(&crc, &test, sizeof(test));
+        lfs_dir_fromle32(&test);
        err = lfs_bd_crc(lfs, tpair[i], sizeof(test),
                (0x7fffffff & test.size) - sizeof(test), &crc);
        if (err) {
@@ -463,8 +512,10 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
            }

            uint32_t crc = 0xffffffff;
+            lfs_dir_tole32(&dir->d);
            lfs_crc(&crc, &dir->d, sizeof(dir->d));
            err = lfs_bd_prog(lfs, dir->pair[0], 0, &dir->d, sizeof(dir->d));
+            lfs_dir_fromle32(&dir->d);
            if (err) {
                if (err == LFS_ERR_CORRUPT) {
                    goto relocate;
@@ -478,7 +529,7 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
            while (newoff < (0x7fffffff & dir->d.size)-4) {
                if (i < count && regions[i].oldoff == oldoff) {
                    lfs_crc(&crc, regions[i].newdata, regions[i].newlen);
-                    err = lfs_bd_prog(lfs, dir->pair[0],
+                    int err = lfs_bd_prog(lfs, dir->pair[0],
                            newoff, regions[i].newdata, regions[i].newlen);
                    if (err) {
                        if (err == LFS_ERR_CORRUPT) {
@@ -492,7 +543,7 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
                    i += 1;
                } else {
                    uint8_t data;
-                    err = lfs_bd_read(lfs, oldpair[1], oldoff, &data, 1);
+                    int err = lfs_bd_read(lfs, oldpair[1], oldoff, &data, 1);
                    if (err) {
                        return err;
                    }
@@ -511,7 +562,9 @@ static int lfs_dir_commit(lfs_t *lfs, lfs_dir_t *dir,
                }
            }

+            crc = lfs_tole32(crc);
            err = lfs_bd_prog(lfs, dir->pair[0], newoff, &crc, 4);
+            crc = lfs_fromle32(crc);
            if (err) {
                if (err == LFS_ERR_CORRUPT) {
                    goto relocate;
@@ -584,11 +637,14 @@ relocate:
 }

 static int lfs_dir_update(lfs_t *lfs, lfs_dir_t *dir,
-        const lfs_entry_t *entry, const void *data) {
-    return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+        lfs_entry_t *entry, const void *data) {
+    lfs_entry_tole32(&entry->d);
+    int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
            {entry->off, sizeof(entry->d), &entry->d, sizeof(entry->d)},
            {entry->off+sizeof(entry->d), entry->d.nlen, data, entry->d.nlen}
        }, data ? 2 : 1);
+    lfs_entry_fromle32(&entry->d);
+    return err;
 }

 static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
@@ -597,10 +653,14 @@ static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
    while (true) {
        if (dir->d.size + lfs_entry_size(entry) <= lfs->cfg->block_size) {
            entry->off = dir->d.size - 4;
-            return lfs_dir_commit(lfs, dir, (struct lfs_region[]){
+
+            lfs_entry_tole32(&entry->d);
+            int err = lfs_dir_commit(lfs, dir, (struct lfs_region[]){
                    {entry->off, 0, &entry->d, sizeof(entry->d)},
                    {entry->off, 0, data, entry->d.nlen}
                }, 2);
+            lfs_entry_fromle32(&entry->d);
+            return err;
        }

        // we need to allocate a new dir block
@@ -614,10 +674,12 @@ static int lfs_dir_append(lfs_t *lfs, lfs_dir_t *dir,
            newdir.d.tail[0] = dir->d.tail[0];
            newdir.d.tail[1] = dir->d.tail[1];
            entry->off = newdir.d.size - 4;
+            lfs_entry_tole32(&entry->d);
            err = lfs_dir_commit(lfs, &newdir, (struct lfs_region[]){
                    {entry->off, 0, &entry->d, sizeof(entry->d)},
                    {entry->off, 0, data, entry->d.nlen}
                }, 2);
+            lfs_entry_fromle32(&entry->d);
            if (err) {
                return err;
            }
@@ -703,6 +765,7 @@ static int lfs_dir_next(lfs_t *lfs, lfs_dir_t *dir, lfs_entry_t *entry) {

    int err = lfs_bd_read(lfs, dir->pair[0], dir->off,
            &entry->d, sizeof(entry->d));
+    lfs_entry_fromle32(&entry->d);
    if (err) {
        return err;
    }
@@ -1002,7 +1065,7 @@ int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
            return LFS_ERR_INVAL;
        }

-        err = lfs_dir_fetch(lfs, dir, dir->d.tail);
+        int err = lfs_dir_fetch(lfs, dir, dir->d.tail);
        if (err) {
            return err;
        }
@@ -1013,7 +1076,6 @@ int lfs_dir_seek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
 }

 lfs_soff_t lfs_dir_tell(lfs_t *lfs, lfs_dir_t *dir) {
-    (void)lfs;
    return dir->pos;
 }

@@ -1065,6 +1127,7 @@ static int lfs_ctz_find(lfs_t *lfs,
                lfs_ctz(current));

        int err = lfs_cache_read(lfs, rcache, pcache, head, 4*skip, &head, 4);
+        head = lfs_fromle32(head);
        if (err) {
            return err;
        }
@@ -1114,7 +1177,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
            if (size != lfs->cfg->block_size) {
                for (lfs_off_t i = 0; i < size; i++) {
                    uint8_t data;
-                    err = lfs_cache_read(lfs, rcache, NULL,
+                    int err = lfs_cache_read(lfs, rcache, NULL,
                            head, i, &data, 1);
                    if (err) {
                        return err;
@@ -1140,8 +1203,10 @@ static int lfs_ctz_extend(lfs_t *lfs,
            lfs_size_t skips = lfs_ctz(index) + 1;

            for (lfs_off_t i = 0; i < skips; i++) {
-                err = lfs_cache_prog(lfs, pcache, rcache,
+                head = lfs_tole32(head);
+                int err = lfs_cache_prog(lfs, pcache, rcache,
                        nblock, 4*i, &head, 4);
+                head = lfs_fromle32(head);
                if (err) {
                    if (err == LFS_ERR_CORRUPT) {
                        goto relocate;
@@ -1152,6 +1217,7 @@ static int lfs_ctz_extend(lfs_t *lfs,
                if (i != skips-1) {
                    err = lfs_cache_read(lfs, rcache, NULL,
                            head, 4*i, &head, 4);
+                    head = lfs_fromle32(head);
                    if (err) {
                        return err;
                    }
@@ -1196,6 +1262,8 @@ static int lfs_ctz_traverse(lfs_t *lfs,
        lfs_block_t heads[2];
        int count = 2 - (index & 1);
        err = lfs_cache_read(lfs, rcache, pcache, head, 0, &heads, count*4);
+        heads[0] = lfs_fromle32(heads[0]);
+        heads[1] = lfs_fromle32(heads[1]);
        if (err) {
            return err;
        }
@@ -1448,7 +1516,7 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
            !lfs_pairisnull(file->pair)) {
        // update dir entry
        lfs_dir_t cwd;
-        err = lfs_dir_fetch(lfs, &cwd, file->pair);
+        int err = lfs_dir_fetch(lfs, &cwd, file->pair);
        if (err) {
            return err;
        }
@@ -1456,11 +1524,16 @@ int lfs_file_sync(lfs_t *lfs, lfs_file_t *file) {
        lfs_entry_t entry = {.off = file->poff};
        err = lfs_bd_read(lfs, cwd.pair[0], entry.off,
                &entry.d, sizeof(entry.d));
+        lfs_entry_fromle32(&entry.d);
        if (err) {
            return err;
        }

-        assert(entry.d.type == LFS_TYPE_REG);
+        if (entry.d.type != LFS_TYPE_REG) {
+            // sanity check valid entry
+            return LFS_ERR_INVAL;
+        }
+
        entry.d.u.file.head = file->head;
        entry.d.u.file.size = file->size;

@@ -1481,7 +1554,7 @@ lfs_ssize_t lfs_file_read(lfs_t *lfs, lfs_file_t *file,
    lfs_size_t nsize = size;

    if ((file->flags & 3) == LFS_O_WRONLY) {
-        return LFS_ERR_BADF;
+        return LFS_ERR_INVAL;
    }

    if (file->flags & LFS_F_WRITING) {
@@ -1537,7 +1610,7 @@ lfs_ssize_t lfs_file_write(lfs_t *lfs, lfs_file_t *file,
    lfs_size_t nsize = size;

    if ((file->flags & 3) == LFS_O_RDONLY) {
-        return LFS_ERR_BADF;
+        return LFS_ERR_INVAL;
    }

    if (file->flags & LFS_F_READING) {
@@ -1660,11 +1733,10 @@ lfs_soff_t lfs_file_seek(lfs_t *lfs, lfs_file_t *file,

 int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
    if ((file->flags & 3) == LFS_O_RDONLY) {
-        return LFS_ERR_BADF;
+        return LFS_ERR_INVAL;
    }

-    lfs_off_t oldsize = lfs_file_size(lfs, file);
-    if (size < oldsize) {
+    if (size < lfs_file_size(lfs, file)) {
        // need to flush since directly changing metadata
        int err = lfs_file_flush(lfs, file);
        if (err) {
@@ -1681,13 +1753,13 @@ int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {

        file->size = size;
        file->flags |= LFS_F_DIRTY;
-    } else if (size > oldsize) {
+    } else if (size > lfs_file_size(lfs, file)) {
        lfs_off_t pos = file->pos;

        // flush+seek if not already at end
-        if (file->pos != oldsize) {
+        if (file->pos != lfs_file_size(lfs, file)) {
            int err = lfs_file_seek(lfs, file, 0, SEEK_END);
-            if (err < 0) {
+            if (err) {
                return err;
            }
        }
@@ -1711,7 +1783,6 @@ int lfs_file_truncate(lfs_t *lfs, lfs_file_t *file, lfs_off_t size) {
 }

 lfs_soff_t lfs_file_tell(lfs_t *lfs, lfs_file_t *file) {
-    (void)lfs;
    return file->pos;
 }

@@ -1725,7 +1796,6 @@ int lfs_file_rewind(lfs_t *lfs, lfs_file_t *file) {
 }

 lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
-    (void)lfs;
    if (file->flags & LFS_F_WRITING) {
        return lfs_max(file->pos, file->size);
    } else {
@@ -1734,7 +1804,7 @@ lfs_soff_t lfs_file_size(lfs_t *lfs, lfs_file_t *file) {
 }


-/// General fs operations ///
+/// General fs oprations ///
 int lfs_stat(lfs_t *lfs, const char *path, struct lfs_info *info) {
    // check for root, can only be something like '/././../.'
    if (strspn(path, "/.") == strlen(path)) {
@@ -1798,7 +1868,7 @@ int lfs_remove(lfs_t *lfs, const char *path) {
        // must be empty before removal, checking size
        // without masking top bit checks for any case where
        // dir is not empty
-        err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
+        int err = lfs_dir_fetch(lfs, &dir, entry.d.u.dir);
        if (err) {
            return err;
        } else if (dir.d.size != sizeof(dir.d)+4) {
@@ -1823,7 +1893,7 @@ int lfs_remove(lfs_t *lfs, const char *path) {
        cwd.d.tail[0] = dir.d.tail[0];
        cwd.d.tail[1] = dir.d.tail[1];

-        err = lfs_dir_commit(lfs, &cwd, NULL, 0);
+        int err = lfs_dir_commit(lfs, &cwd, NULL, 0);
        if (err) {
            return err;
        }
@@ -1872,7 +1942,7 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {

    // must have same type
    if (prevexists && preventry.d.type != oldentry.d.type) {
-        return LFS_ERR_ISDIR;
+        return LFS_ERR_INVAL;
    }

    lfs_dir_t dir;
@@ -1880,11 +1950,11 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
        // must be empty before removal, checking size
        // without masking top bit checks for any case where
        // dir is not empty
-        err = lfs_dir_fetch(lfs, &dir, preventry.d.u.dir);
+        int err = lfs_dir_fetch(lfs, &dir, preventry.d.u.dir);
        if (err) {
            return err;
        } else if (dir.d.size != sizeof(dir.d)+4) {
-            return LFS_ERR_NOTEMPTY;
+            return LFS_ERR_INVAL;
        }
    }

@@ -1907,12 +1977,12 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
    newentry.d.nlen = strlen(newpath);

    if (prevexists) {
-        err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
+        int err = lfs_dir_update(lfs, &newcwd, &newentry, newpath);
        if (err) {
            return err;
        }
    } else {
-        err = lfs_dir_append(lfs, &newcwd, &newentry, newpath);
+        int err = lfs_dir_append(lfs, &newcwd, &newentry, newpath);
        if (err) {
            return err;
        }
@@ -1940,7 +2010,7 @@ int lfs_rename(lfs_t *lfs, const char *oldpath, const char *newpath) {
        newcwd.d.tail[0] = dir.d.tail[0];
        newcwd.d.tail[1] = dir.d.tail[1];

-        err = lfs_dir_commit(lfs, &newcwd, NULL, 0);
+        int err = lfs_dir_commit(lfs, &newcwd, NULL, 0);
        if (err) {
            return err;
        }
@@ -2032,11 +2102,11 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
    // create free lookahead
    memset(lfs->free.buffer, 0, lfs->cfg->lookahead/8);
    lfs->free.begin = 0;
-    lfs->free.size = lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
    lfs->free.off = 0;
-    lfs_alloc_ack(lfs);
+    lfs->free.end = lfs->free.begin + lfs->free.off + lfs->cfg->block_count;

    // create superblock dir
+    lfs_alloc_ack(lfs);
    lfs_dir_t superdir;
    err = lfs_dir_alloc(lfs, &superdir);
    if (err) {
@@ -2064,7 +2134,7 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
        .d.type = LFS_TYPE_SUPERBLOCK,
        .d.elen = sizeof(superblock.d) - sizeof(superblock.d.magic) - 4,
        .d.nlen = sizeof(superblock.d.magic),
-        .d.version = LFS_DISK_VERSION,
+        .d.version = 0x00010001,
        .d.magic = {"littlefs"},
        .d.block_size  = lfs->cfg->block_size,
        .d.block_count = lfs->cfg->block_count,
@@ -2075,9 +2145,10 @@ int lfs_format(lfs_t *lfs, const struct lfs_config *cfg) {
    superdir.d.size = sizeof(superdir.d) + sizeof(superblock.d) + 4;

    // write both pairs to be safe
+    lfs_superblock_tole32(&superblock.d);
    bool valid = false;
    for (int i = 0; i < 2; i++) {
-        err = lfs_dir_commit(lfs, &superdir, (struct lfs_region[]){
+        int err = lfs_dir_commit(lfs, &superdir, (struct lfs_region[]){
                {sizeof(superdir.d), sizeof(superblock.d),
                 &superblock.d, sizeof(superblock.d)}
            }, 1);
@@ -2109,10 +2180,9 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
    }

    // setup free lookahead
-    lfs->free.begin = 0;
-    lfs->free.size = 0;
-    lfs->free.off = 0;
-    lfs_alloc_ack(lfs);
+    lfs->free.begin = -lfs_min(lfs->cfg->lookahead, lfs->cfg->block_count);
+    lfs->free.off = -lfs->free.begin;
+    lfs->free.end = lfs->free.begin + lfs->free.off + lfs->cfg->block_count;

    // load superblock
    lfs_dir_t dir;
@@ -2123,8 +2193,9 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
    }

    if (!err) {
-        err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
+        int err = lfs_bd_read(lfs, dir.pair[0], sizeof(dir.d),
                &superblock.d, sizeof(superblock.d));
+        lfs_superblock_fromle32(&superblock.d);
        if (err) {
            return err;
        }
@@ -2138,11 +2209,10 @@ int lfs_mount(lfs_t *lfs, const struct lfs_config *cfg) {
        return LFS_ERR_CORRUPT;
    }

-    uint16_t major_version = (0xffff & (superblock.d.version >> 16));
-    uint16_t minor_version = (0xffff & (superblock.d.version >>  0));
-    if ((major_version != LFS_DISK_VERSION_MAJOR ||
-         minor_version > LFS_DISK_VERSION_MINOR)) {
-        LFS_ERROR("Invalid version %d.%d", major_version, minor_version);
+    if (superblock.d.version > (0x00010001 | 0x0000ffff)) {
+        LFS_ERROR("Invalid version %d.%d",
+                0xffff & (superblock.d.version >> 16),
+                0xffff & (superblock.d.version >> 0));
        return LFS_ERR_INVAL;
    }

@@ -2180,15 +2250,16 @@ int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {

        // iterate over contents
        while (dir.off + sizeof(entry.d) <= (0x7fffffff & dir.d.size)-4) {
-            err = lfs_bd_read(lfs, dir.pair[0], dir.off,
+            int err = lfs_bd_read(lfs, dir.pair[0], dir.off,
                    &entry.d, sizeof(entry.d));
+            lfs_entry_fromle32(&entry.d);
            if (err) {
                return err;
            }

            dir.off += lfs_entry_size(&entry);
            if ((0x70 & entry.d.type) == (0x70 & LFS_TYPE_REG)) {
-                err = lfs_ctz_traverse(lfs, &lfs->rcache, NULL,
+                int err = lfs_ctz_traverse(lfs, &lfs->rcache, NULL,
                        entry.d.u.file.head, entry.d.u.file.size, cb, data);
                if (err) {
                    return err;
@@ -2222,7 +2293,7 @@ int lfs_traverse(lfs_t *lfs, int (*cb)(void*, lfs_block_t), void *data) {
            }
        }
    }
-    
+
    return 0;
 }

@@ -2242,7 +2313,7 @@ static int lfs_pred(lfs_t *lfs, const lfs_block_t dir[2], lfs_dir_t *pdir) {
            return true;
        }

-        err = lfs_dir_fetch(lfs, pdir, pdir->d.tail);
+        int err = lfs_dir_fetch(lfs, pdir, pdir->d.tail);
        if (err) {
            return err;
        }
@@ -2256,7 +2327,7 @@ static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
    if (lfs_pairisnull(lfs->root)) {
        return 0;
    }
-    
+
    parent->d.tail[0] = 0;
    parent->d.tail[1] = 1;

@@ -2268,7 +2339,7 @@ static int lfs_parent(lfs_t *lfs, const lfs_block_t dir[2],
        }

        while (true) {
-            err = lfs_dir_next(lfs, parent, entry);
+            int err = lfs_dir_next(lfs, parent, entry);
            if (err && err != LFS_ERR_NOENT) {
                return err;
            }
@@ -2302,13 +2373,13 @@ static int lfs_moved(lfs_t *lfs, const void *e) {
    // iterate over all directory directory entries
    lfs_entry_t entry;
    while (!lfs_pairisnull(cwd.d.tail)) {
-        err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
+        int err = lfs_dir_fetch(lfs, &cwd, cwd.d.tail);
        if (err) {
            return err;
        }

        while (true) {
-            err = lfs_dir_next(lfs, &cwd, &entry);
+            int err = lfs_dir_next(lfs, &cwd, &entry);
            if (err && err != LFS_ERR_NOENT) {
                return err;
            }
@@ -2317,7 +2388,7 @@ static int lfs_moved(lfs_t *lfs, const void *e) {
                break;
            }

-            if (!(0x80 & entry.d.type) && 
+            if (!(0x80 & entry.d.type) &&
                 memcmp(&entry.d.u, e, sizeof(entry.d.u)) == 0) {
                return true;
            }
@@ -2439,7 +2510,7 @@ int lfs_deorphan(lfs_t *lfs) {
        // check entries for moves
        lfs_entry_t entry;
        while (true) {
-            err = lfs_dir_next(lfs, &cwd, &entry);
+            int err = lfs_dir_next(lfs, &cwd, &entry);
            if (err && err != LFS_ERR_NOENT) {
                return err;
            }
@@ -2458,7 +2529,7 @@ int lfs_deorphan(lfs_t *lfs) {
                if (moved) {
                    LFS_DEBUG("Found move %d %d",
                            entry.d.u.dir[0], entry.d.u.dir[1]);
-                    err = lfs_dir_remove(lfs, &cwd, &entry);
+                    int err = lfs_dir_remove(lfs, &cwd, &entry);
                    if (err) {
                        return err;
                    }
@@ -2466,7 +2537,7 @@ int lfs_deorphan(lfs_t *lfs) {
                    LFS_DEBUG("Found partial move %d %d",
                            entry.d.u.dir[0], entry.d.u.dir[1]);
                    entry.d.type &= ~0x80;
-                    err = lfs_dir_update(lfs, &cwd, &entry, NULL);
+                    int err = lfs_dir_update(lfs, &cwd, &entry, NULL);
                    if (err) {
                        return err;
                    }
--- a/lfs.h
+++ b/lfs.h
@@ -22,23 +22,6 @@
 #include <stdbool.h>


-/// Version info ///
-
-// Software library version
-// Major (top-nibble), incremented on backwards incompatible changes
-// Minor (bottom-nibble), incremented on feature additions
-#define LFS_VERSION 0x00010002
-#define LFS_VERSION_MAJOR (0xffff & (LFS_VERSION >> 16))
-#define LFS_VERSION_MINOR (0xffff & (LFS_VERSION >>  0))
-
-// Version of On-disk data structures
-// Major (top-nibble), incremented on backwards incompatible changes
-// Minor (bottom-nibble), incremented on feature additions
-#define LFS_DISK_VERSION 0x00010001
-#define LFS_DISK_VERSION_MAJOR (0xffff & (LFS_DISK_VERSION >> 16))
-#define LFS_DISK_VERSION_MINOR (0xffff & (LFS_DISK_VERSION >>  0))
-
-
 /// Definitions ///

 // Type definitions
@@ -66,7 +49,6 @@ enum lfs_error {
    LFS_ERR_NOTDIR   = -20,  // Entry is not a dir
    LFS_ERR_ISDIR    = -21,  // Entry is a dir
    LFS_ERR_NOTEMPTY = -39,  // Dir is not empty
-    LFS_ERR_BADF     = -9,   // Bad file number
    LFS_ERR_INVAL    = -22,  // Invalid parameter
    LFS_ERR_NOSPC    = -28,  // No space left on device
    LFS_ERR_NOMEM    = -12,  // No more memory available
@@ -260,9 +242,8 @@ typedef struct lfs_superblock {

 typedef struct lfs_free {
    lfs_block_t begin;
-    lfs_block_t size;
+    lfs_block_t end;
    lfs_block_t off;
-    lfs_block_t ack;
    uint32_t *buffer;
 } lfs_free_t;

--- a/lfs_util.h
+++ b/lfs_util.h
@@ -49,6 +49,23 @@ static inline int lfs_scmp(uint32_t a, uint32_t b) {
    return (int)(unsigned)(a - b);
 }

+static inline uint32_t lfs_fromle32(uint32_t a) {
+#if defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    return a;
+#elif defined(__BYTE_ORDER__) && __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+    return __builtin_bswap32(a);
+#else
+    return (((uint8_t*)&a)[0] <<  0) |
+           (((uint8_t*)&a)[1] <<  8) |
+           (((uint8_t*)&a)[2] << 16) |
+           (((uint8_t*)&a)[3] << 24);
+#endif
+}
+
+static inline uint32_t lfs_tole32(uint32_t a) {
+    return lfs_fromle32(a);
+}
+
 // CRC-32 with polynomial = 0x04c11db7
 void lfs_crc(uint32_t *crc, const void *buffer, size_t size);

--- a/tests/template.fmt
+++ b/tests/template.fmt
@@ -7,11 +7,11 @@


 // test stuff
-static void test_log(const char *s, uintmax_t v) {{
+void test_log(const char *s, uintmax_t v) {{
    printf("%s: %jd\n", s, v);
 }}

-static void test_assert(const char *file, unsigned line,
+void test_assert(const char *file, unsigned line,
        const char *s, uintmax_t v, uintmax_t e) {{
    static const char *last[6] = {{0, 0}};
    if (v != e || !(last[0] == s || last[1] == s ||
@@ -37,8 +37,7 @@ static void test_assert(const char *file, unsigned line,


 // utility functions for traversals
-static int __attribute__((used)) test_count(void *p, lfs_block_t b) {{
-    (void)b;
+int test_count(void *p, lfs_block_t b) {{
    unsigned *u = (unsigned*)p;
    *u += 1;
    return 0;
@@ -59,7 +58,7 @@ lfs_size_t size;
 lfs_size_t wsize;
 lfs_size_t rsize;

-uintmax_t test;
+uintmax_t res;

 #ifndef LFS_READ_SIZE
 #define LFS_READ_SIZE 16
@@ -97,7 +96,7 @@ const struct lfs_config cfg = {{


 // Entry point
-int main(void) {{
+int main() {{
    lfs_emubd_create(&cfg, "blocks");

 {tests}
--- a/tests/test.py
+++ b/tests/test.py
@@ -14,26 +14,19 @@ def generate(test):
        match = re.match('(?: *\n)*( *)(.*)=>(.*);', line, re.DOTALL | re.MULTILINE)
        if match:
            tab, test, expect = match.groups()
-            lines.append(tab+'test = {test};'.format(test=test.strip()))
-            lines.append(tab+'test_assert("{name}", test, {expect});'.format(
+            lines.append(tab+'res = {test};'.format(test=test.strip()))
+            lines.append(tab+'test_assert("{name}", res, {expect});'.format(
                    name = re.match('\w*', test.strip()).group(),
                    expect = expect.strip()))
        else:
            lines.append(line)

-    # Create test file
    with open('test.c', 'w') as file:
        file.write(template.format(tests='\n'.join(lines)))

-    # Remove build artifacts to force rebuild
-    try:
-        os.remove('test.o')
-        os.remove('lfs')
-    except OSError:
-        pass
-
 def compile():
-    subprocess.check_call(['make', '--no-print-directory', '-s'])
+    os.environ['CFLAGS'] = os.environ.get('CFLAGS', '') + ' -Werror'
+    subprocess.check_call(['make', '--no-print-directory', '-s'], env=os.environ)

 def execute():
    subprocess.check_call(["./lfs"])
--- a/tests/test_alloc.sh
+++ b/tests/test_alloc.sh
@@ -266,40 +266,6 @@ tests/test.py << TEST
    lfs_mkdir(&lfs, "exhaustiondir2") => LFS_ERR_NOSPC;
 TEST

-echo "--- Split dir test ---"
-rm -rf blocks
-tests/test.py << TEST
-    lfs_format(&lfs, &cfg) => 0;
-TEST
-tests/test.py << TEST
-    lfs_mount(&lfs, &cfg) => 0;
-
-    // create one block whole for half a directory
-    lfs_file_open(&lfs, &file[0], "bump", LFS_O_WRONLY | LFS_O_CREAT) => 0;
-    lfs_file_write(&lfs, &file[0], (void*)"hi", 2) => 2;
-    lfs_file_close(&lfs, &file[0]) => 0;
-
-    lfs_file_open(&lfs, &file[0], "exhaustion", LFS_O_WRONLY | LFS_O_CREAT);
-    size = strlen("blahblahblahblah");
-    memcpy(buffer, "blahblahblahblah", size);
-    for (lfs_size_t i = 0;
-            i < (cfg.block_count-6)*(cfg.block_size-8);
-            i += size) {
-        lfs_file_write(&lfs, &file[0], buffer, size) => size;
-    }
-    lfs_file_close(&lfs, &file[0]) => 0;
-
-    // open whole
-    lfs_remove(&lfs, "bump") => 0;
-
-    lfs_mkdir(&lfs, "splitdir") => 0;
-    lfs_file_open(&lfs, &file[0], "splitdir/bump",
-            LFS_O_WRONLY | LFS_O_CREAT) => 0;
-    lfs_file_write(&lfs, &file[0], buffer, size) => LFS_ERR_NOSPC;
-    lfs_file_close(&lfs, &file[0]) => 0;
-
-    lfs_unmount(&lfs) => 0;
-TEST

 echo "--- Results ---"
 tests/stats.py
--- a/tests/test_dirs.sh
+++ b/tests/test_dirs.sh
@@ -220,7 +220,7 @@ tests/test.py << TEST
    lfs_mount(&lfs, &cfg) => 0;
    lfs_mkdir(&lfs, "warmpotato") => 0;
    lfs_mkdir(&lfs, "warmpotato/mushy") => 0;
-    lfs_rename(&lfs, "hotpotato", "warmpotato") => LFS_ERR_NOTEMPTY;
+    lfs_rename(&lfs, "hotpotato", "warmpotato") => LFS_ERR_INVAL;

    lfs_remove(&lfs, "warmpotato/mushy") => 0;
    lfs_rename(&lfs, "hotpotato", "warmpotato") => 0;
--- a/tests/test_truncate.sh
+++ b/tests/test_truncate.sh
@@ -13,12 +13,10 @@ TEST

 truncate_test() {
 STARTSIZES="$1"
-STARTSEEKS="$2"
-HOTSIZES="$3"
-COLDSIZES="$4"
+HOTSIZES="$2"
+COLDSIZES="$3"
 tests/test.py << TEST
    static const lfs_off_t startsizes[] = {$STARTSIZES};
-    static const lfs_off_t startseeks[] = {$STARTSEEKS};
    static const lfs_off_t hotsizes[]   = {$HOTSIZES};

    lfs_mount(&lfs, &cfg) => 0;
@@ -35,11 +33,6 @@ tests/test.py << TEST
        }
        lfs_file_size(&lfs, &file[0]) => startsizes[i];

-        if (startseeks[i] != startsizes[i]) {
-            lfs_file_seek(&lfs, &file[0],
-                    startseeks[i], LFS_SEEK_SET) => startseeks[i];
-        }
-
        lfs_file_truncate(&lfs, &file[0], hotsizes[i]) => 0;
        lfs_file_size(&lfs, &file[0]) => hotsizes[i];

@@ -114,21 +107,18 @@ TEST

 echo "--- Cold shrinking truncate ---"
 truncate_test \
-    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE"

 echo "--- Cold expanding truncate ---"
 truncate_test \
-    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE"

 echo "--- Warm shrinking truncate ---"
 truncate_test \
-    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
    "           0,            0,            0,            0,            0"
@@ -136,21 +126,6 @@ truncate_test \
 echo "--- Warm expanding truncate ---"
 truncate_test \
    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
-    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
-    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
-    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE"
-
-echo "--- Mid-file shrinking truncate ---"
-truncate_test \
-    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
-    "  $LARGESIZE,   $LARGESIZE,   $LARGESIZE,   $LARGESIZE,   $LARGESIZE" \
-    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
-    "           0,            0,            0,            0,            0"
-
-echo "--- Mid-file expanding truncate ---"
-truncate_test \
-    "           0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE, 2*$LARGESIZE" \
-    "           0,            0,   $SMALLSIZE,  $MEDIUMSIZE,   $LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE" \
    "2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE, 2*$LARGESIZE"