diff options
Diffstat (limited to 'tvix/nix-compat/src/nar/writer/wire.rs')
-rw-r--r-- | tvix/nix-compat/src/nar/writer/wire.rs | 110 |
1 files changed, 0 insertions, 110 deletions
diff --git a/tvix/nix-compat/src/nar/writer/wire.rs b/tvix/nix-compat/src/nar/writer/wire.rs deleted file mode 100644 index a6c19f0759c3..000000000000 --- a/tvix/nix-compat/src/nar/writer/wire.rs +++ /dev/null @@ -1,110 +0,0 @@ -//! NAR wire format, without I/O details, since those differ between -//! the synchronous and asynchronous implementations. -//! -//! The wire format is an S-expression format, encoded onto the wire -//! using simple encoding rules. -//! -//! # Encoding -//! -//! Lengths are represented as 64-bit unsigned integers in little-endian -//! format. Byte strings, including file contents and syntactic strings -//! part of the grammar, are prefixed by their 64-bit length, and padded -//! to 8-byte (64-bit) alignment with zero bytes. The zero-length string -//! is therefore encoded as eight zero bytes representing its length. -//! -//! # Grammar -//! -//! The NAR grammar is as follows: -//! ```plain -//! archive ::= "nix-archive-1" node -//! -//! node ::= "(" "type" "symlink" "target" string ")" -//! ||= "(" "type" "regular" ("executable" "")? "contents" string ")" -//! ||= "(" "type" "directory" entry* ")" -//! -//! entry ::= "entry" "(" "name" string "node" node ")" -//! ``` -//! -//! We rewrite it to pull together the purely syntactic elements into -//! unified tokens, producing an equivalent grammar that can be parsed -//! and serialized more elegantly: -//! ```plain -//! archive ::= TOK_NAR node -//! node ::= TOK_SYM string TOK_PAR -//! ||= (TOK_REG | TOK_EXE) string TOK_PAR -//! ||= TOK_DIR entry* TOK_PAR -//! -//! entry ::= TOK_ENT string TOK_NOD node TOK_PAR -//! -//! TOK_NAR ::= "nix-archive-1" "(" "type" -//! TOK_SYM ::= "symlink" "target" -//! TOK_REG ::= "regular" "contents" -//! TOK_EXE ::= "regular" "executable" "" -//! TOK_DIR ::= "directory" -//! TOK_ENT ::= "entry" "(" "name" -//! TOK_NOD ::= "node" "(" "type" -//! TOK_PAR ::= ")" -//! ``` -//! -//! # Restrictions -//! -//! NOTE: These restrictions are not (and cannot be) enforced by this module, -//! but must be enforced by its consumers, [super::reader] and [super::writer]. -//! -//! Directory entry names cannot have the reserved names `.` and `..`, nor contain -//! forward slashes. They must appear in strictly ascending lexicographic order -//! within a directory, and can be at most [MAX_NAME_LEN] bytes in length. -//! -//! Symlink targets can be at most [MAX_TARGET_LEN] bytes in length. -//! -//! Neither is permitted to be empty, or contain null bytes. - -// These values are the standard Linux length limits -/// Maximum length of a directory entry name -pub const MAX_NAME_LEN: usize = 255; -/// Maximum length of a symlink target -pub const MAX_TARGET_LEN: usize = 4095; - -#[cfg(test)] -fn token(xs: &[&str]) -> Vec<u8> { - let mut out = vec![]; - for x in xs { - let len = x.len() as u64; - out.extend_from_slice(&len.to_le_bytes()); - out.extend_from_slice(x.as_bytes()); - - let n = x.len() & 7; - if n != 0 { - const ZERO: [u8; 8] = [0; 8]; - out.extend_from_slice(&ZERO[n..]); - } - } - out -} - -pub const TOK_NAR: [u8; 56] = *b"\x0d\0\0\0\0\0\0\0nix-archive-1\0\0\0\x01\0\0\0\0\0\0\0(\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0type\0\0\0\0"; -pub const TOK_SYM: [u8; 32] = *b"\x07\0\0\0\0\0\0\0symlink\0\x06\0\0\0\0\0\0\0target\0\0"; -pub const TOK_REG: [u8; 32] = *b"\x07\0\0\0\0\0\0\0regular\0\x08\0\0\0\0\0\0\0contents"; -pub const TOK_EXE: [u8; 64] = *b"\x07\0\0\0\0\0\0\0regular\0\x0a\0\0\0\0\0\0\0executable\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x08\0\0\0\0\0\0\0contents"; -pub const TOK_DIR: [u8; 24] = *b"\x09\0\0\0\0\0\0\0directory\0\0\0\0\0\0\0"; -pub const TOK_ENT: [u8; 48] = *b"\x05\0\0\0\0\0\0\0entry\0\0\0\x01\0\0\0\0\0\0\0(\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0name\0\0\0\0"; -pub const TOK_NOD: [u8; 48] = *b"\x04\0\0\0\0\0\0\0node\0\0\0\0\x01\0\0\0\0\0\0\0(\0\0\0\0\0\0\0\x04\0\0\0\0\0\0\0type\0\0\0\0"; -pub const TOK_PAR: [u8; 16] = *b"\x01\0\0\0\0\0\0\0)\0\0\0\0\0\0\0"; - -#[test] -fn tokens() { - let cases: &[(&[u8], &[&str])] = &[ - (&TOK_NAR, &["nix-archive-1", "(", "type"]), - (&TOK_SYM, &["symlink", "target"]), - (&TOK_REG, &["regular", "contents"]), - (&TOK_EXE, &["regular", "executable", "", "contents"]), - (&TOK_DIR, &["directory"]), - (&TOK_ENT, &["entry", "(", "name"]), - (&TOK_NOD, &["node", "(", "type"]), - (&TOK_PAR, &[")"]), - ]; - - for &(tok, xs) in cases { - assert_eq!(tok, token(xs)); - } -} |