feat: ADD EXIF striping #3

Dockerfile

@@ -2,6 +2,11 @@ FROM docker.io/ubuntu:24.04
 
 WORKDIR /app
 
+# exiftool: strips EXIF/GPS metadata from published images (see build.sh)
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends libimage-exiftool-perl \
+ && rm -rf /var/lib/apt/lists/*
+
 # Copy project files
 COPY build.sh /app/
 COPY templates /app/templates

README.md

@@ -12,7 +12,8 @@ Simple SSG to create dynamic gallery one-pagers in your shell! Shell+Gallery
 ## Features
 
 **Available**:
-- Simple use without dependencies
+- Simple use, single dependency (exiftool)
+- Removes EXIF/GPS metadata from published images by default
 - no Javascript
 - Lightbox of image with anchor
 - Order of images via filename
@@ -21,7 +22,6 @@ Simple SSG to create dynamic gallery one-pagers in your shell! Shell+Gallery
 
 **Ideas**:
 - check file formats
-- remove exif data
 - conf file for options
 - anonymize file names
 - sections via file names
@@ -30,6 +30,17 @@ Simple SSG to create dynamic gallery one-pagers in your shell! Shell+Gallery
 
 ---
 
+## Requirements
+
+- `bash` and GNU coreutils
+- [`exiftool`](https://exiftool.org/) - `apt install libimage-exiftool-perl` (Debian/Ubuntu) or `brew install exiftool` (macOS)
+
+Docker/Podman users need nothing on the host, exiftool is baked into the image.
+
+Building with `--keep-exif` / `STRIP_EXIF=0` does not require exiftool.
+
+---
+
 ## Usage
 
 ### Docker / Podman
@@ -59,6 +70,22 @@ docker run -v $(pwd)/images:/app/images -v $(pwd)/output:/app/output localhost/s
 
 The generated gallery will be in `./output/index.html`
 
+### Metadata removal
+
+EXIF, GPS, IPTC and XMP metadata is stripped from every image by default. Only the copies
+in `./output/` are processed, your originals in `./images/` are never modified.
+
+To publish images with their metadata intact:
+
+```bash
+./build.sh --keep-exif
+# or
+STRIP_EXIF=0 ./build.sh
+
+# container
+podman run -e STRIP_EXIF=0 -v $(pwd)/images:/app/images -v $(pwd)/output:/app/output git.uphillsecurity.com/cf7/shellery:latest
+```
+
 ---
 
 ## Notes

build.sh

@@ -10,6 +10,29 @@ OUTPUT_DIR="output"
 TEMPLATES_DIR="templates"
 ASSETS_DIR="assets"
 
+# Image metadata (EXIF/GPS/IPTC/XMP) is stripped by default.
+# Opt out with STRIP_EXIF=0 or --keep-exif.
+STRIP_EXIF="${STRIP_EXIF:-1}"
+
+for arg in "$@"; do
+    case "$arg" in
+        --keep-exif) STRIP_EXIF=0 ;;
+        -h|--help)
+            echo "usage: ./build.sh [--keep-exif]"
+            echo "  --keep-exif   do not strip image metadata (env: STRIP_EXIF=0)"
+            exit 0 ;;
+        *) echo "unknown option: $arg" >&2; exit 1 ;;
+    esac
+done
+
+# Fail before writing any output if the default cannot be honoured
+if [[ "$STRIP_EXIF" == "1" ]] && ! command -v exiftool >/dev/null 2>&1; then
+    echo "error: exiftool is required to strip image metadata." >&2
+    echo "  install: apt install libimage-exiftool-perl   (or: brew install exiftool)" >&2
+    echo "  bypass:  STRIP_EXIF=0 ./build.sh   or   ./build.sh --keep-exif" >&2
+    exit 1
+fi
+
 # Create output directory
 mkdir -p "$OUTPUT_DIR"
 
@@ -57,7 +80,18 @@ done
 # Copy assets
 cp -r "$ASSETS_DIR"/* "$OUTPUT_DIR/"
 
-# Copy images
+# Copy images, then strip metadata from the copies (originals are never touched)
 cp -r "$IMAGES_DIR" "$OUTPUT_DIR/"
 
+if [[ "$STRIP_EXIF" == "1" ]]; then
+    if compgen -G "$OUTPUT_DIR/$IMAGES_DIR/*" > /dev/null; then
+        if ! exiftool -all= -overwrite_original -q -q "$OUTPUT_DIR/$IMAGES_DIR"; then
+            echo "error: exiftool failed; output images may still contain metadata" >&2
+            exit 1
+        fi
+    fi
+else
+    echo "warning: EXIF stripping disabled, image metadata will be published as-is" >&2
+fi
+
 echo "Gallery generated successfully in $OUTPUT_DIR/index.html"