Decoder/inspector example

Author: kornelski

rmp/examples/inspect.rs

@@ -0,0 +1,135 @@
+use std::fmt;
+use std::io::{self, Read};
+use rmp::{decode::*, Marker};
+
+fn main() {
+    let path = std::env::args_os().nth(1).expect("Specify path to a file with msgpack content");
+    let data = std::fs::read(&path).expect(&path.to_string_lossy());
+
+    dump(&mut Indent { i: 0, start: true }, &mut data.as_slice()).unwrap();
+}
+
+fn dump(indent: &mut Indent, rd: &mut &[u8]) -> Result<(), Box<dyn std::error::Error>> {
+    match read_marker(rd).map_err(ValueReadError::from)? {
+        Marker::FixPos(n) => print!("U0({n})"),
+        Marker::FixNeg(n) => print!("I0({n})"),
+        Marker::Null => print!("Null"),
+        Marker::True => print!("True"),
+        Marker::False => print!("False"),
+        Marker::U8 => print!("U8({})", rd.read_data_u8()?),
+        Marker::U16 => print!("U16({})", rd.read_data_u16()?),
+        Marker::U32 => print!("U32({})", rd.read_data_u32()?),
+        Marker::U64 => print!("U64({})", rd.read_data_u64()?),
+        Marker::I8 => print!("I8({})", rd.read_data_i8()?),
+        Marker::I16 => print!("I16({})", rd.read_data_i16()?),
+        Marker::I32 => print!("I32({})", rd.read_data_i32()?),
+        Marker::I64 => print!("I64({})", rd.read_data_i64()?),
+        Marker::F32 => print!("F32({})", rd.read_data_f32()?),
+        Marker::F64 => print!("F64({})", rd.read_data_f64()?),
+        Marker::FixStr(len) => print!("Str0(\"{}\")", read_str_data(len.into(), rd)?),
+        Marker::Str8 => print!("Str8(\"{}\")", read_str_data(rd.read_data_u8()?.into(), rd)?),
+        Marker::Str16 => print!("Str16(\"{}\")", read_str_data(rd.read_data_u16()?.into(), rd)?),
+        Marker::Str32 => print!("Str32(\"{}\")", read_str_data(rd.read_data_u32()?.into(), rd)?),
+        Marker::Bin8 => print!("Bin8({})", HexDump(&read_bin_data(rd.read_data_u8()?.into(), rd)?)),
+        Marker::Bin16 => print!("Bin16({})", HexDump(&read_bin_data(rd.read_data_u16()?.into(), rd)?)),
+        Marker::Bin32 => print!("Bin32({})", HexDump(&read_bin_data(rd.read_data_u32()?.into(), rd)?)),
+        Marker::FixArray(len) => dump_array(indent, 0, len.into(), rd)?,
+        Marker::Array16 => dump_array(indent, 16, rd.read_data_u16()?.into(), rd)?,
+        Marker::Array32 => dump_array(indent, 32, rd.read_data_u32()?.into(), rd)?,
+        Marker::FixMap(len) => dump_map(indent, 0, len.into(), rd)?,
+        Marker::Map16 => dump_map(indent, 16, rd.read_data_u16()?.into(), rd)?,
+        Marker::Map32 => dump_map(indent, 32, rd.read_data_u32()?.into(), rd)?,
+        Marker::FixExt1 => todo!(),
+        Marker::FixExt2 => todo!(),
+        Marker::FixExt4 => todo!(),
+        Marker::FixExt8 => todo!(),
+        Marker::FixExt16 => todo!(),
+        Marker::Ext8 => todo!(),
+        Marker::Ext16 => todo!(),
+        Marker::Ext32 => todo!(),
+        Marker::Reserved => todo!(),
+    }
+    Ok(())
+}
+
+fn dump_map(indent: &mut Indent, ty: u8, len: u32, rd: &mut &[u8]) -> Result<(), Box<dyn std::error::Error>> {
+    indent.print(format_args!("Map{ty}{{"));
+    let multiline = len > 1;
+    if multiline { indent.ln(); } else { print!(" ") }
+    indent.ind();
+    for i in 0..len {
+        indent.print(""); dump(indent, rd)?; print!(": ");  dump(indent, rd)?;
+        if multiline {  print!(","); indent.ln(); } else if i+1 != len { print!(", ") }
+    }
+    indent.out();
+    indent.print(format_args!("}}"));
+    Ok(())
+}
+
+fn dump_array(indent: &mut Indent, ty: u8, len: u32, rd: &mut &[u8]) -> Result<(), Box<dyn std::error::Error>> {
+    indent.print(format_args!("Array{ty}["));
+    let multiline = len > 1;
+    if multiline { indent.ln(); } else { print!(" ") }
+    indent.ind();
+    for i in 0..len {
+        indent.print(""); dump(indent, rd)?;
+        if multiline {  print!(","); indent.ln(); } else if i+1 != len { print!(", ") }
+    }
+    indent.out();
+    indent.print("]");
+    Ok(())
+}
+
+fn read_str_data<R: Read>(len: u32, rd: &mut R) -> Result<String, io::Error> {
+    Ok(String::from_utf8_lossy(&read_bin_data(len, rd)?).into_owned())
+}
+
+fn read_bin_data<R: Read>(len: u32, rd: &mut R) -> Result<Vec<u8>, io::Error> {
+    let mut buf = Vec::with_capacity(len.min(1<<16) as usize);
+    let bytes_read = rd.take(len as u64).read_to_end(&mut buf)?;
+    if bytes_read != len as usize {
+        return Err(io::ErrorKind::UnexpectedEof.into());
+    }
+    Ok(buf)
+}
+
+struct Indent { i: u16, start: bool }
+impl Indent {
+    fn print(&mut self, args: impl fmt::Display) {
+        print!("{:w$}{args}", "", w = if self.start { (self.i as usize) * 2 } else { 0 });
+        self.start = false;
+    }
+
+    pub fn ind(&mut self) {
+        self.i += 1;
+    }
+
+    pub fn ln(&mut self) {
+        println!();
+        self.start = true;
+    }
+
+    pub fn out(&mut self) {
+        self.i -= 1;
+    }
+}
+
+struct HexDump<'a>(&'a [u8]);
+impl fmt::Display for HexDump<'_> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let truncate = self.0.len() > 50;
+        if truncate {
+            f.write_fmt(format_args!("{}B ", self.0.len()))?;
+        }
+
+        for &b in &self.0[0.. (if truncate { 50 } else { self.0.len() })] {
+            f.write_fmt(format_args!("{b:02x}"))?;
+        }
+
+        if truncate {
+            f.write_str("…")?;
+        }
+        Ok(())
+    }
+}
+