Files
stoatchat/crates/services/autumn/src/exif.rs
2025-08-15 02:07:26 +01:00

162 lines
6.4 KiB
Rust

use std::io::{Cursor, Read};
use exif::Reader;
use image::{ImageFormat, ImageReader};
use revolt_database::Metadata;
use revolt_result::{create_error, Result, ToRevoltError};
use tempfile::NamedTempFile;
use tokio::process::Command;
/// Strip EXIF data from given file and produce new file and metadata
pub async fn strip_metadata(
file: NamedTempFile,
buf: Vec<u8>,
metadata: Metadata,
mime: &str,
) -> Result<(Vec<u8>, Metadata)> {
match &metadata {
Metadata::Image { width, height } => match mime {
// // little_exif does not appear to parse JPEGs correctly? had 2/2 files fail
// "image/jpeg" | "image/png" => {
// // use little_exif to strip metadata except for orientation and colour profile
// // PNGs must also be re-encoded to mitigate CVE-2023-21036
// let metadata = revolt_little_exif::metadata::Metadata::new_from_path_with_filetype(
// file.path(),
// match mime {
// "image/jpeg" => revolt_little_exif::filetype::FileExtension::JPEG,
// "image/png" => revolt_little_exif::filetype::FileExtension::PNG {
// as_zTXt_chunk: true,
// },
// _ => unreachable!(),
// },
// )
// .unwrap();
// dbg!(metadata.data());
// todo!()
// }
// Apply orientation manually & strip all other EXIF data
"image/jpeg" | "image/png" | "image/avif" | "image/tiff" => {
// Create a reader
let mut cursor = Cursor::new(buf);
// Decode the image
let image = ImageReader::new(&mut cursor)
.with_guessed_format()
.to_internal_error()?
.decode()
.to_internal_error()?;
// Reset read position
cursor.set_position(0);
// Extract orientation data
let exif_reader = Reader::new();
let rotation = match exif_reader.read_from_container(&mut cursor) {
Ok(exif) => match exif.get_field(exif::Tag::Orientation, exif::In::PRIMARY) {
Some(orientation) => orientation.value.get_uint(0).unwrap_or_default(),
_ => 0,
},
_ => 0,
};
// Create a buffer to write to
let mut bytes: Vec<u8> = Vec::new();
let mut writer = Cursor::new(&mut bytes);
// Apply the EXIF rotation
// See https://jdhao.github.io/2019/07/31/image_rotation_exif_info/
match &rotation {
2 => image.fliph(),
3 => image.rotate180(),
4 => image.rotate180().fliph(),
5 => image.rotate90().fliph(),
6 => image.rotate90(),
7 => image.rotate270().fliph(),
8 => image.rotate270(),
_ => image,
}
.write_to(
&mut writer,
match mime {
"image/jpeg" => ImageFormat::Jpeg,
"image/png" => ImageFormat::Png,
"image/avif" => ImageFormat::Avif,
"image/tiff" => ImageFormat::Tiff,
_ => todo!(),
},
).to_internal_error()?;
// Calculate dimensions after rotation.
let (width, height) = match &rotation {
2 | 4 | 5 | 7 => (*height, *width),
_ => (*width, *height),
};
Ok((bytes, Metadata::Image { width, height }))
}
// JXLs store EXIF data but we don't have the ability to write them
"image/jxl" => Ok((buf, metadata)),
// All other images that cannot store EXIF data
_ => Ok((buf, metadata)),
},
// Use ffmpeg to copy video stream and probe new metadata
Metadata::Video { .. } => match mime {
// Strip EXIF data by copying video stream
"video/mp4" | "video/webm" | "video/quicktime" => {
// Pick the correct file format for ffmpeg
let ext = match mime {
"video/mp4" => "mp4",
"video/webm" => "webm",
"video/quicktime" => "mov",
_ => unreachable!(),
};
// Temporary output file
let mut out_file = NamedTempFile::new().to_internal_error()?;
// Process the file with ffmpeg
Command::new("ffmpeg")
.args([
// Overwrite the temporary file
"-y",
// Read original uploaded file
"-i",
file.path().to_str().ok_or(create_error!(InternalError))?,
// Strip any metadata
"-map_metadata",
"-1",
// Copy video / audio data to new file
"-c:v",
"copy",
"-c:a",
"copy",
// Select correct file format
"-f",
ext,
// Save to new temporary file
out_file
.path()
.to_str()
.ok_or(create_error!(InternalError))?,
])
.output()
.await
.to_internal_error()?;
// Probe the file again
let metadata = crate::metadata::generate_metadata(&out_file, mime);
// Read the file from disk
let mut buf = Vec::<u8>::new();
out_file.read_to_end(&mut buf).to_internal_error()?;
Ok((buf, metadata))
}
// Assume all other video formats cannot store EXIF data
_ => Ok((buf, metadata)),
},
// all other file types don't store EXIF data
_ => Ok((buf, metadata)),
}
}