| //! All binary files generated by measureme have a simple file header that |
| //! consists of a 4 byte file magic string and a 4 byte little-endian version |
| //! number. |
| use std::convert::TryInto; |
| use std::error::Error; |
| use std::path::Path; |
| |
| pub const CURRENT_FILE_FORMAT_VERSION: u32 = 9; |
| |
| pub const FILE_MAGIC_TOP_LEVEL: &[u8; 4] = b"MMPD"; |
| pub const FILE_MAGIC_EVENT_STREAM: &[u8; 4] = b"MMES"; |
| pub const FILE_MAGIC_STRINGTABLE_DATA: &[u8; 4] = b"MMSD"; |
| pub const FILE_MAGIC_STRINGTABLE_INDEX: &[u8; 4] = b"MMSI"; |
| |
| pub const FILE_EXTENSION: &str = "mm_profdata"; |
| |
| /// The size of the file header in bytes. Note that functions in this module |
| /// rely on this size to be `8`. |
| pub const FILE_HEADER_SIZE: usize = 8; |
| |
| pub fn write_file_header( |
| s: &mut dyn std::io::Write, |
| file_magic: &[u8; 4], |
| ) -> Result<(), Box<dyn Error + Send + Sync>> { |
| // The implementation here relies on FILE_HEADER_SIZE to have the value 8. |
| // Let's make sure this assumption cannot be violated without being noticed. |
| assert_eq!(FILE_HEADER_SIZE, 8); |
| |
| s.write_all(file_magic).map_err(Box::new)?; |
| s.write_all(&CURRENT_FILE_FORMAT_VERSION.to_le_bytes()) |
| .map_err(Box::new)?; |
| |
| Ok(()) |
| } |
| |
| #[must_use] |
| pub fn verify_file_header( |
| bytes: &[u8], |
| expected_magic: &[u8; 4], |
| diagnostic_file_path: Option<&Path>, |
| stream_tag: &str, |
| ) -> Result<(), Box<dyn Error + Send + Sync>> { |
| // The implementation here relies on FILE_HEADER_SIZE to have the value 8. |
| // Let's make sure this assumption cannot be violated without being noticed. |
| assert_eq!(FILE_HEADER_SIZE, 8); |
| |
| let diagnostic_file_path = diagnostic_file_path.unwrap_or(Path::new("<in-memory>")); |
| |
| if bytes.len() < FILE_HEADER_SIZE { |
| let msg = format!( |
| "Error reading {} stream in file `{}`: Expected file to contain at least `{:?}` bytes but found `{:?}` bytes", |
| stream_tag, |
| diagnostic_file_path.display(), |
| FILE_HEADER_SIZE, |
| bytes.len() |
| ); |
| |
| return Err(From::from(msg)); |
| } |
| |
| let actual_magic = &bytes[0..4]; |
| |
| if actual_magic != expected_magic { |
| let msg = format!( |
| "Error reading {} stream in file `{}`: Expected file magic `{:?}` but found `{:?}`", |
| stream_tag, |
| diagnostic_file_path.display(), |
| expected_magic, |
| actual_magic |
| ); |
| |
| return Err(From::from(msg)); |
| } |
| |
| let file_format_version = u32::from_le_bytes(bytes[4..8].try_into().unwrap()); |
| |
| if file_format_version != CURRENT_FILE_FORMAT_VERSION { |
| let msg = format!( |
| "Error reading {} stream in file `{}`: Expected file format version {} but found `{}`", |
| stream_tag, |
| diagnostic_file_path.display(), |
| CURRENT_FILE_FORMAT_VERSION, |
| file_format_version |
| ); |
| |
| return Err(From::from(msg)); |
| } |
| |
| Ok(()) |
| } |
| |
| pub fn strip_file_header(data: &[u8]) -> &[u8] { |
| &data[FILE_HEADER_SIZE..] |
| } |
| |
| #[cfg(test)] |
| mod tests { |
| use super::*; |
| use crate::{PageTag, SerializationSinkBuilder}; |
| |
| #[test] |
| fn roundtrip() { |
| let data_sink = SerializationSinkBuilder::new_in_memory().new_sink(PageTag::Events); |
| |
| write_file_header(&mut data_sink.as_std_write(), FILE_MAGIC_EVENT_STREAM).unwrap(); |
| |
| let data = data_sink.into_bytes(); |
| |
| verify_file_header(&data, FILE_MAGIC_EVENT_STREAM, None, "test").unwrap(); |
| } |
| |
| #[test] |
| fn invalid_magic() { |
| let data_sink = SerializationSinkBuilder::new_in_memory().new_sink(PageTag::Events); |
| write_file_header(&mut data_sink.as_std_write(), FILE_MAGIC_STRINGTABLE_DATA).unwrap(); |
| let mut data = data_sink.into_bytes(); |
| |
| // Invalidate the filemagic |
| data[2] = 0; |
| assert!(verify_file_header(&data, FILE_MAGIC_STRINGTABLE_DATA, None, "test").is_err()); |
| } |
| |
| #[test] |
| fn other_version() { |
| let data_sink = SerializationSinkBuilder::new_in_memory().new_sink(PageTag::Events); |
| |
| write_file_header(&mut data_sink.as_std_write(), FILE_MAGIC_STRINGTABLE_INDEX).unwrap(); |
| |
| let mut data = data_sink.into_bytes(); |
| |
| // Change version |
| data[4] = 0xFF; |
| data[5] = 0xFF; |
| data[6] = 0xFF; |
| data[7] = 0xFF; |
| assert!(verify_file_header(&data, FILE_MAGIC_STRINGTABLE_INDEX, None, "test").is_err()); |
| } |
| |
| #[test] |
| fn empty_file() { |
| let data: [u8; 0] = []; |
| |
| assert!(verify_file_header(&data, FILE_MAGIC_STRINGTABLE_DATA, None, "test").is_err()); |
| } |
| } |