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//! Read and decode blobs
use crate::block::{HeaderBlock, PrimitiveBlock};
use crate::error::{new_blob_error, new_error, new_protobuf_error, BlobError, ErrorKind, Result};
use crate::proto::fileformat;
use byteorder::ReadBytesExt;
use protobuf::Message;
use std::fs::File;
use std::io::{BufReader, Read, Seek, SeekFrom};
use std::path::Path;
use flate2::read::ZlibDecoder;
/// Maximum allowed [`BlobHeader`] size in bytes.
pub static MAX_BLOB_HEADER_SIZE: u64 = 64 * 1024;
/// Maximum allowed uncompressed [`Blob`] content size in bytes.
pub static MAX_BLOB_MESSAGE_SIZE: u64 = 32 * 1024 * 1024;
/// The content type of a blob.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum BlobType<'a> {
/// Blob contains a [`HeaderBlock`].
OsmHeader,
/// Blob contains a [`PrimitiveBlock`].
OsmData,
/// An unknown blob type with the given string identifier.
/// Parsers should ignore unknown blobs they do not expect.
Unknown(&'a str),
}
impl<'a> BlobType<'a> {
pub const fn as_str(&self) -> &'a str {
match self {
Self::OsmHeader => "OSMHeader",
Self::OsmData => "OSMData",
Self::Unknown(x) => x,
}
}
}
//TODO rename variants to fit proto files
/// The decoded content of a blob (analogous to [`BlobType`]).
#[derive(Clone, Debug)]
pub enum BlobDecode<'a> {
/// Blob contains a [`HeaderBlock`].
OsmHeader(Box<HeaderBlock>),
/// Blob contains a [`PrimitiveBlock`].
OsmData(PrimitiveBlock),
/// An unknown blob type with the given string identifier.
/// Parsers should ignore unknown blobs they do not expect.
Unknown(&'a str),
}
/// The offset of a blob in bytes from stream start.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct ByteOffset(pub u64);
/// A blob.
///
/// A PBF file consists of a sequence of blobs. This type supports decoding the content of a blob
/// to different types of blocks that are usually more interesting to the user.
#[derive(Clone, Debug)]
pub struct Blob {
header: fileformat::BlobHeader,
blob: fileformat::Blob,
offset: Option<ByteOffset>,
}
impl Blob {
fn new(
header: fileformat::BlobHeader,
blob: fileformat::Blob,
offset: Option<ByteOffset>,
) -> Blob {
Blob {
header,
blob,
offset,
}
}
/// Decodes the Blob and tries to obtain the inner content (usually a [`HeaderBlock`] or a
/// [`PrimitiveBlock`]). This operation might involve an expensive decompression step.
pub fn decode(&self) -> Result<BlobDecode> {
match self.get_type() {
BlobType::OsmHeader => {
let block = Box::new(self.to_headerblock()?);
Ok(BlobDecode::OsmHeader(block))
}
BlobType::OsmData => {
let block = self.to_primitiveblock()?;
Ok(BlobDecode::OsmData(block))
}
BlobType::Unknown(x) => Ok(BlobDecode::Unknown(x)),
}
}
/// Returns the type of a blob without decoding its content.
pub fn get_type(&self) -> BlobType {
match self.header.type_() {
x if x == BlobType::OsmHeader.as_str() => BlobType::OsmHeader,
x if x == BlobType::OsmData.as_str() => BlobType::OsmData,
x => BlobType::Unknown(x),
}
}
/// Returns the byte offset of the blob from the start of its source stream.
/// This might be [`None`] if the source stream does not implement [`Seek`].
pub fn offset(&self) -> Option<ByteOffset> {
self.offset
}
/// Tries to decode the blob to a [`HeaderBlock`]. This operation might involve an expensive
/// decompression step.
pub fn to_headerblock(&self) -> Result<HeaderBlock> {
decode_blob(&self.blob).map(HeaderBlock::new)
}
/// Tries to decode the blob to a [`PrimitiveBlock`]. This operation might involve an expensive
/// decompression step.
pub fn to_primitiveblock(&self) -> Result<PrimitiveBlock> {
decode_blob(&self.blob).map(PrimitiveBlock::new)
}
}
/// A blob header.
///
/// Just contains information about the size and type of the following [`Blob`].
#[derive(Clone, Debug)]
pub struct BlobHeader {
header: fileformat::BlobHeader,
}
impl BlobHeader {
fn new(header: fileformat::BlobHeader) -> Self {
BlobHeader { header }
}
/// Returns the type of the following blob.
pub fn blob_type(&self) -> BlobType {
match self.header.type_() {
"OSMHeader" => BlobType::OsmHeader,
"OSMData" => BlobType::OsmData,
x => BlobType::Unknown(x),
}
}
/// Returns the size of the following blob in bytes.
pub fn get_blob_size(&self) -> i32 {
self.header.datasize()
}
}
/// A reader for PBF files that allows iterating over [`Blob`]s.
#[derive(Clone, Debug)]
pub struct BlobReader<R: Read + Send> {
reader: R,
/// Current reader offset in bytes from the start of the stream.
offset: Option<ByteOffset>,
last_blob_ok: bool,
}
impl<R: Read + Send> BlobReader<R> {
/// Creates a new `BlobReader`.
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let f = std::fs::File::open("tests/test.osm.pbf")?;
/// let buf_reader = std::io::BufReader::new(f);
///
/// let reader = BlobReader::new(buf_reader);
///
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn new(reader: R) -> BlobReader<R> {
BlobReader {
reader,
offset: None,
last_blob_ok: true,
}
}
fn read_blob_header(&mut self) -> Option<Result<fileformat::BlobHeader>> {
let header_size: u64 = match self.reader.read_u32::<byteorder::BigEndian>() {
Ok(n) => {
self.offset = self.offset.map(|x| ByteOffset(x.0 + 4));
u64::from(n)
}
Err(e) => {
self.offset = None;
return match e.kind() {
::std::io::ErrorKind::UnexpectedEof => {
//TODO This also accepts corrupted files in the case of 1-3 available bytes
None
}
_ => {
self.last_blob_ok = false;
Some(Err(new_blob_error(BlobError::InvalidHeaderSize)))
}
};
}
};
if header_size >= MAX_BLOB_HEADER_SIZE {
self.last_blob_ok = false;
return Some(Err(new_blob_error(BlobError::HeaderTooBig {
size: header_size,
})));
}
let mut reader = self.reader.by_ref().take(header_size);
let header = match fileformat::BlobHeader::parse_from_reader(&mut reader) {
Ok(header) => header,
Err(e) => {
self.offset = None;
self.last_blob_ok = false;
return Some(Err(new_protobuf_error(e, "blob header")));
}
};
self.offset = self.offset.map(|x| ByteOffset(x.0 + header_size));
Some(Ok(header))
}
}
impl BlobReader<BufReader<File>> {
/// Tries to open the file at the given path and constructs a `BlobReader` from this.
/// If there are no errors, each blob will have a valid ([`Some`]) offset.
///
/// # Errors
/// Returns the same errors that `std::fs::File::open` returns.
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let reader = BlobReader::from_path("tests/test.osm.pbf")?;
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn from_path<P: AsRef<Path>>(path: P) -> Result<Self> {
let f = File::open(path)?;
let reader = BufReader::new(f);
Ok(BlobReader {
reader,
offset: Some(ByteOffset(0)),
last_blob_ok: true,
})
}
}
impl<R: Read + Send> Iterator for BlobReader<R> {
type Item = Result<Blob>;
fn next(&mut self) -> Option<Self::Item> {
// Stop iteration if there was an error.
if !self.last_blob_ok {
return None;
}
let prev_offset = self.offset;
let header = match self.read_blob_header() {
Some(Ok(header)) => header,
Some(Err(err)) => return Some(Err(err)),
None => return None,
};
let mut reader = self.reader.by_ref().take(header.datasize() as u64);
let blob = match fileformat::Blob::parse_from_reader(&mut reader) {
Ok(blob) => blob,
Err(e) => {
self.offset = None;
self.last_blob_ok = false;
return Some(Err(new_protobuf_error(e, "blob content")));
}
};
self.offset = self
.offset
.map(|x| ByteOffset(x.0 + header.datasize() as u64));
Some(Ok(Blob::new(header, blob, prev_offset)))
}
}
impl<R: Read + Seek + Send> BlobReader<R> {
/// Creates a new `BlobReader` from the given reader that is seekable and will be initialized
/// with a valid offset.
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let f = std::fs::File::open("tests/test.osm.pbf")?;
/// let buf_reader = std::io::BufReader::new(f);
///
/// let mut reader = BlobReader::new_seekable(buf_reader)?;
/// let first_blob = reader.next().unwrap()?;
///
/// assert_eq!(first_blob.offset(), Some(ByteOffset(0)));
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn new_seekable(mut reader: R) -> Result<BlobReader<R>> {
let pos = reader.stream_position()?;
Ok(BlobReader {
reader,
offset: Some(ByteOffset(pos)),
last_blob_ok: true,
})
}
/// Read and return the [`Blob`] at the given offset. If successful, the cursor of the stream is
/// positioned at the start of the next [`Blob`].
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let mut reader = BlobReader::from_path("tests/test.osm.pbf")?;
/// let first_blob = reader.next().unwrap()?;
/// let second_blob = reader.next().unwrap()?;
///
/// let offset = first_blob.offset().unwrap();
/// let first_blob_again = reader.blob_from_offset(offset)?;
/// assert_eq!(first_blob.offset(), first_blob_again.offset());
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn blob_from_offset(&mut self, pos: ByteOffset) -> Result<Blob> {
self.seek(pos)?;
self.next().unwrap_or_else(|| {
Err(new_error(ErrorKind::Io(::std::io::Error::new(
::std::io::ErrorKind::UnexpectedEof,
"no blob at this stream position",
))))
})
}
/// Seek to an offset in bytes from the start of the stream.
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let mut reader = BlobReader::from_path("tests/test.osm.pbf")?;
/// let first_blob = reader.next().unwrap()?;
/// let second_blob = reader.next().unwrap()?;
///
/// reader.seek(first_blob.offset().unwrap())?;
///
/// let first_blob_again = reader.next().unwrap()?;
/// assert_eq!(first_blob.offset(), first_blob_again.offset());
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn seek(&mut self, pos: ByteOffset) -> Result<()> {
match self.reader.seek(SeekFrom::Start(pos.0)) {
Ok(offset) => {
self.offset = Some(ByteOffset(offset));
Ok(())
}
Err(e) => {
self.offset = None;
Err(e.into())
}
}
}
/// Seek to an offset in bytes. (See `std::io::Seek`)
pub fn seek_raw(&mut self, pos: SeekFrom) -> Result<u64> {
match self.reader.seek(pos) {
Ok(offset) => {
self.offset = Some(ByteOffset(offset));
Ok(offset)
}
Err(e) => {
self.offset = None;
Err(e.into())
}
}
}
/// Read and return next [`BlobHeader`] but skip the following [`Blob`]. This allows really fast
/// iteration of the PBF structure if only the byte offset and [`BlobType`] are important.
/// On success, returns the [`BlobHeader`] and the byte offset of the header which can also be
/// used as an offset for reading the entire [`Blob`] (including header).
pub fn next_header_skip_blob(&mut self) -> Option<Result<(BlobHeader, Option<ByteOffset>)>> {
// Stop iteration if there was an error.
if !self.last_blob_ok {
return None;
}
let prev_offset = self.offset;
// read header
let header = match self.read_blob_header() {
Some(Ok(header)) => header,
Some(Err(err)) => return Some(Err(err)),
None => return None,
};
// skip blob (which also adjusts self.offset)
if let Err(err) = self.seek_raw(SeekFrom::Current(header.datasize() as i64)) {
self.last_blob_ok = false;
return Some(Err(err));
}
Some(Ok((BlobHeader::new(header), prev_offset)))
}
}
impl BlobReader<BufReader<File>> {
/// Creates a new `BlobReader` from the given path that is seekable and will be initialized
/// with a valid offset.
///
/// # Example
/// ```
/// use osmpbf::*;
///
/// # fn foo() -> Result<()> {
/// let mut reader = BlobReader::seekable_from_path("tests/test.osm.pbf")?;
/// let first_blob = reader.next().unwrap()?;
///
/// assert_eq!(first_blob.offset(), Some(ByteOffset(0)));
/// # Ok(())
/// # }
/// # foo().unwrap();
/// ```
pub fn seekable_from_path<P: AsRef<Path>>(path: P) -> Result<BlobReader<BufReader<File>>> {
let f = File::open(path.as_ref())?;
let buf_reader = BufReader::new(f);
Self::new_seekable(buf_reader)
}
}
pub(crate) fn decode_blob<T: Message>(blob: &fileformat::Blob) -> Result<T> {
if blob.has_raw() {
let size = blob.raw().len() as u64;
if size < MAX_BLOB_MESSAGE_SIZE {
T::parse_from_bytes(blob.raw()).map_err(|e| new_protobuf_error(e, "raw blob data"))
} else {
Err(new_blob_error(BlobError::MessageTooBig { size }))
}
} else if blob.has_zlib_data() {
let mut decoder = ZlibDecoder::new(blob.zlib_data()).take(MAX_BLOB_MESSAGE_SIZE);
T::parse_from_reader(&mut decoder).map_err(|e| new_protobuf_error(e, "blob zlib data"))
} else {
Err(new_blob_error(BlobError::Empty))
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_get_type() {
let pairs = [
("", BlobType::Unknown("")),
("abc", BlobType::Unknown("abc")),
("OSMHeader", BlobType::OsmHeader),
("OSMData", BlobType::OsmData),
];
for (string, blob_type) in &pairs {
let mut ff_header = fileformat::BlobHeader::new();
ff_header.set_type(string.to_string());
let ff_blob = fileformat::Blob::new();
let blob = Blob::new(ff_header, ff_blob, None);
assert_eq!(blob.get_type(), *blob_type);
}
}
}