Update Docker image and macOS instructions

Dockerfile

@@ -1,15 +1,17 @@
-FROM debian:bookworm
-
-# Install requirments
-RUN apt update && apt install -y wget parted gzip pigz xz-utils udev e2fsprogs && apt clean
-
-# Setup Env
-ENV LANG=C.UTF-8
-ENV TERM=xterm-256color
-ENV DEBIAN_FRONTEND=noninteractive
-WORKDIR /workdir
-
-# Copy pishrink in
-COPY pishrink.sh /usr/local/bin/pishrink
-RUN chmod +x /usr/local/bin/pishrink
-ENTRYPOINT [ "/usr/local/bin/pishrink" ]
+FROM debian:stable-slim
+
+# 1) Install PiShrink prereqs
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends \
+      e2fsprogs dosfstools parted xz-utils squashfs-tools kpartx ca-certificates curl \
+ && rm -rf /var/lib/apt/lists/*
+
+# 2) Copy in PiShrink & our wrapper
+COPY pishrink.sh shrink-wrapper.sh /usr/local/bin/
+
+# 3) Fix the shebang on pishrink, rename for tidiness, and chmod both
+RUN mv /usr/local/bin/pishrink.sh /usr/local/bin/pishrink \
+ && mv /usr/local/bin/shrink-wrapper.sh /usr/local/bin/shrink-wrapper \
+ && chmod +x /usr/local/bin/pishrink /usr/local/bin/shrink-wrapper
+
+# — no ENTRYPOINT or CMD —

README.md

@@ -1,11 +1,14 @@
+# PiShrink
 
-# PiShrink #
+PiShrink is a bash script that automatically shrink a pi image that will then
+resize to the max size of the SD card on boot. This will make putting the
+image back onto the SD card faster and the shrunk images will compress better.
 
-PiShrink is a bash script that automatically shrink a pi image that will then resize to the max size of the SD card on boot. This will make putting the image back onto the SD card faster and the shrunk images will compress better.
-In addition the shrunk image can be compressed with gzip and xz to create an even smaller image. Parallel compression of the image
-using multiple cores is supported.
+In addition the shrunk image can be compressed with gzip and xz to create an
+even smaller image. Parallel compression of the image using multiple cores is
+supported.
 
-## Usage ##
+## Usage
 
 ```text
 Usage: pishrink.sh [-adhnrsvzZ] imagefile.img [newimagefile.img]
@@ -20,7 +23,9 @@ Usage: pishrink.sh [-adhnrsvzZ] imagefile.img [newimagefile.img]
   -d         Write debug messages in a debug log file
 ```
 
-If you specify the `newimagefile.img` parameter, the script will make a copy of `imagefile.img` and work off that. You will need enough space to make a full copy of the image to use that option.
+If you specify the `newimagefile.img` parameter, the script will make a copy
+of `imagefile.img` and work off that. You will need enough space to make a
+full copy of the image to use that option.
 
 * `-s` prevents automatic filesystem expansion on the images next boot
 * `-v` enables more verbose output
@@ -31,24 +36,31 @@ If you specify the `newimagefile.img` parameter, the script will make a copy of
 * `-a` will use option -f9 for pigz and option -T0 for xz and compress in parallel.
 * `-d` will create a logfile `pishrink.log` which may help for problem analysis.
 
-Default options for compressors can be overwritten by defining PISHRINK_GZIP or PSHRINK_XZ environment variables for gzip and xz.
+Default options for compressors can be overwritten by defining PISHRINK_GZIP
+or PSHRINK_XZ environment variables for gzip and xz.
 
-## Prerequisites ##
+## Prerequisites
 
-If you are running PiShrink in VirtualBox you will likely encounter an error if you
-attempt to use VirtualBox's "Shared Folder" feature. You can copy the image you wish to
-shrink on to the VM from a Shared Folder, but shrinking directly from the Shared Folder
-is know to cause issues.
+If you are running PiShrink in VirtualBox you will likely encounter an error
+if you attempt to use VirtualBox's "Shared Folder" feature. You can copy the
+image you wish to shrink on to the VM from a Shared Folder, but shrinking
+directly from the Shared Folder is know to cause issues.
 
-If using Ubuntu, you will likely see an error about `e2fsck` being out of date and `metadata_csum`. The simplest fix for this is to use Ubuntu 16.10 and up, as it will save you a lot of hassle in the long run.
+If using Ubuntu, you will likely see an error about `e2fsck` being out of date
+and `metadata_csum`. The simplest fix for this is to use Ubuntu 16.10 and up,
+as it will save you a lot of hassle in the long run.
 
-PiShrink will shrink the last partition of your image. If that partition is not ext2, ext3, or ext4 it will not be able to shrink your image.
-If the last partition is not the root filesystem partition, auto resizing will not run on boot.
-If you want to use auto resizing on a distro using Systemd, you should ensure you [Enabled /etc/rc.local Compatibility](https://www.linuxbabe.com/linux-server/how-to-enable-etcrc-local-with-systemd).
+PiShrink will shrink the last partition of your image. If that partition is
+not ext2, ext3, or ext4 it will not be able to shrink your image. If the last
+partition is not the root filesystem partition, auto resizing will not run on
+boot.
 
-## Installation ##
+If you want to use auto resizing on a distro using Systemd, you should ensure you have
+[enabled /etc/rc.local Compatibility](https://www.linuxbabe.com/linux-server/how-to-enable-etcrc-local-with-systemd).
 
-### Linux Instructions ###
+## Installation
+
+### Linux Instructions
 
 If you are on Debian/Ubuntu you can install all the packages you would need by running: `sudo apt update && sudo apt install -y wget parted gzip pigz xz-utils udev e2fsprogs`
 
@@ -60,7 +72,7 @@ chmod +x pishrink.sh
 sudo mv pishrink.sh /usr/local/bin
 ```
 
-### Windows Instructions ###
+### Windows Instructions
 
 PiShrink can be ran on Windows using [Windows Subsystem for Linux](https://learn.microsoft.com/en-us/windows/wsl/about) (WSL 2).
 
@@ -69,56 +81,70 @@ PiShrink can be ran on Windows using [Windows Subsystem for Linux](https://learn
 3. Run `sudo apt update && sudo apt install -y wget parted gzip pigz xz-utils udev e2fsprogs`
 4. Go to the Linux Instructions section above, do that and you're good to go! Your C:\ drive is mounted at /mnt/c/
 
-### MacOS Instructions ###
+### MacOS Instructions
 
 > [!NOTE]
 > These instructions were sourced from the community and should work on Intel and M1 Macs.
 
 1. [Installer Docker](https://docs.docker.com/docker-for-mac/install/).
+
 2. Clone this repo and cd into the pishrink directory:
+
    ```bash
    git clone https://github.com/Drewsif/PiShrink && cd PiShrink
    ```
-4. Build the container by running:
+
+3. Build the container by running:
+
    ```bash
    docker build -t pishrink .
    ```
-6. Create an alias to run PiShrink:
+
+4. Create an alias to run PiShrink:
+
    ```bash
-   echo "alias pishrink='docker run -it --rm --privileged=true -v $(pwd):/workdir pishrink'" >> ~/.bashrc && source ~/.bashrc
+   echo 'alias pishrink='"'"'bash -c '\''docker run --rm --privileged \
+   -v "$(dirname "$1")":/workdir \
+   -v pishrink-data:/data \
+   pishrink shrink-wrapper "$(basename "$1")"'\'' --'"'" >> ~/.zshrc \
+   && source ~/.zshrc
    ```
 
 You can now run the `pishrink` command as normal to shrink your images.
 
 > [!WARNING]  
 > You MUST change directory into the images folder for this command to work. The command mounts your current working directory into the container so absolute file paths will not work. Relative paths should work just fine as long as they are below your current directory.
 
-## Example ##
+## Example
 
 ```bash
-[user@localhost PiShrink]$ sudo pishrink.sh pi.img
-e2fsck 1.42.9 (28-Dec-2013)
-Pass 1: Checking inodes, blocks, and sizes
-Pass 2: Checking directory structure
-Pass 3: Checking directory connectivity
-Pass 4: Checking reference counts
-Pass 5: Checking group summary information
-/dev/loop1: 88262/1929536 files (0.2% non-contiguous), 842728/7717632 blocks
-resize2fs 1.42.9 (28-Dec-2013)
-resize2fs 1.42.9 (28-Dec-2013)
-Resizing the filesystem on /dev/loop1 to 773603 (4k) blocks.
-Begin pass 2 (max = 100387)
+$ pishrink ./Pi4.img
+PiShrink v24.10.23 - https://github.com/Drewsif/PiShrink
+
+pishrink: Gathering data
+pishrink: An existing /etc/rc.local was not found, autoexpand may fail...
+grep: /tmp/tmp.giNzGcvdz6/etc/rc.local: No such file or directory
+Creating new /etc/rc.local
+pishrink: Checking filesystem
+rootfs: 84324/1805104 files (0.2% non-contiguous), 726932/7426560 blocks
+resize2fs 1.47.0 (5-Feb-2023)
+pishrink: Shrinking filesystem
+resize2fs 1.47.0 (5-Feb-2023)
+Resizing the filesystem on /dev/loop0 to 808844 (4k) blocks.
+Begin pass 2 (max = 197810)
 Relocating blocks             XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-Begin pass 3 (max = 236)
+Begin pass 3 (max = 227)
 Scanning inode table          XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-Begin pass 4 (max = 7348)
-Updating inode references     XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
-The filesystem on /dev/loop1 is now 773603 blocks long.
+The filesystem on /dev/loop0 is now 808844 (4k) blocks long.
 
-Shrunk pi.img from 30G to 3.1G
+pishrink: Zeroing any free space left
+pishrink: Zeroed 701M
+pishrink: Shrinking partition
+pishrink: Truncating image
+pishrink: Shrunk /data/Pi4.img from 29G to 3.6G
 ```
 
-## Contributing ##
+## Contributing
 
 If you find a bug please create an issue for it. If you would like a new feature added, you can create an issue for it but I can't promise that I will get to it.
 

shrink-wrapper.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -e
+
+IMG="$1"
+SRC_DIR="/workdir"
+TMP_DIR="/data"
+
+if [[ -z "$IMG" ]]; then
+  echo "Usage: pishrink <image-file>" >&2
+  exit 1
+fi
+
+# 1) Copy the host image into the VM’s native volume
+mkdir -p "$TMP_DIR"
+cp "$SRC_DIR/$IMG" "$TMP_DIR/$IMG"
+
+# 2) Shrink it in-place inside the VM filesystem
+pishrink "$TMP_DIR/$IMG"
+
+# 3) Copy the result back to the shared folder
+cp "$TMP_DIR/$IMG" "$SRC_DIR/${IMG%.img}-shrunk.img"