feat: initial pest grammar & code

Cargo.toml

@@ -20,7 +20,7 @@ lazy_static = { version = "1.4.0", default-features = false }
 log = { version = "0.4.19", default-features = false, features = ["max_level_trace", "release_max_level_info"] }
 nix = { version = "0.26.2", default-features = false, features = ["fs"] }
 pest = { version = "2.7.10", default-features = false, features = ["std", "memchr"], optional = true }
-pest_derive = { version = "2.7.10", default-features = false, features = ["std"], optional = true}
+pest_derive = { version = "2.7.10", default-features = false, features = ["std", "grammar-extras"], optional = true}
 rand = { version = "0.8.5", default-features = false, features = ["std", "std_rng"] }
 regex = { version = "1.9.1", default-features = false, features = ["std", "perf"] }
 serde = { version = "1.0.193", default-features = false, features = ["std", "derive"] }

src/strace/parser/peg.pest

@@ -1,13 +1,32 @@
 // "382944      0.000054 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f52a332e000"
 
-syscall_line = { SOI ~ pid ~ " "+ ~ timestamp ~ " " ~ name ~ arguments ~ " = " ~ ret ~ EOI }
+syscall_line = { SOI ~ pid ~ " "+ ~ rel_ts ~ " " ~ name ~ arguments ~ " = " ~ ret_val ~ EOI }
 
 pid = { ASCII_DIGIT+ }
 
-timestamp = { ASCII_DIGIT+ ~ "." ~ ASCII_DIGIT+ }
+rel_ts = { ASCII_DIGIT+ ~ "." ~ ASCII_DIGIT+ }
 
-name = { (ASCII_ALPHA_LOWER ~ ASCII_DIGIT ~ "_")+ }
+name = { (ASCII_ALPHA_LOWER | ASCII_DIGIT | "_")+ }
 
-arguments = { "(" ~ ANY* ~ ")" }
+arguments = { 
+	"(" ~ 
+	(
+		(argument ~ (", " ~ argument)+)
+		|
+		argument?
+	) ~
+	")"
+}
 
-ret = { ANY+ }
+argument = { expression_int }
+
+ret_val = { expression_int_literal }
+
+
+expression_int = { #or = expression_int_or | #lit = expression_int_literal | #named = expression_named_constant }
+expression_int_literal = { #hex = literal_int_hex | #int = literal_int }
+expression_int_or = { expression_named_constant ~ ("|" ~ expression_int)+ }
+expression_named_constant = { (ASCII_ALPHA_UPPER | ASCII_DIGIT | "_")+ }
+
+literal_int_hex = { "0x" ~ ASCII_HEX_DIGIT+ }
+literal_int = { "-"? ~ ASCII_DIGIT+ }

src/strace/parser/peg.rs

@@ -1,8 +1,9 @@
 //! PEG based strace output parser
 
+use pest::iterators::Pair;
 use pest::Parser as _;
 
-use crate::strace::Syscall;
+use crate::strace::{IntegerExpression, Syscall, SyscallArg};
 
 use super::ParseResult;
 
@@ -11,7 +12,103 @@ use super::ParseResult;
 struct PegParser;
 
 pub fn parse_line(line: &str, unfinished_syscalls: &[Syscall]) -> anyhow::Result<ParseResult> {
-    let res = PegParser::parse(Rule::syscall_line, line);
-    dbg!(&res);
-    todo!();
+    let pair = match PegParser::parse(Rule::syscall_line, line) {
+        Err(_) => return Ok(ParseResult::IgnoredLine),
+        Ok(mut p) => p.next().unwrap(),
+    };
+    dbg!(&pair);
+    Ok(ParseResult::Syscall(pair.into()))
+}
+
+fn pair_descend(pair: Pair<'_, Rule>, levels: usize) -> Option<Pair<'_, Rule>> {
+    let mut pair = pair;
+    let mut levels = levels;
+    while levels > 0 {
+        if let Some(below_pair) = pair.into_inner().next() {
+            pair = below_pair;
+        } else {
+            return None;
+        }
+        levels -= 1;
+    }
+    Some(pair)
+}
+
+fn int_literal_pair_val<T>(pair: Pair<Rule>) -> Option<T>
+where
+    T: From<i128>,
+{
+    let val: Option<i128> = match pair.as_node_tag() {
+        Some("hex") => pair
+            .as_str()
+            .strip_prefix("0x")
+            .and_then(|s| i128::from_str_radix(s, 16).ok()),
+        Some("int") => pair.as_str().parse().ok(),
+        _ => unreachable!(),
+    };
+    val.map(|v| v.into())
+}
+
+impl From<Pair<'_, Rule>> for IntegerExpression {
+    fn from(pair: Pair<Rule>) -> Self {
+        match pair.as_node_tag() {
+            Some("lit") => {
+                let lit_pair = pair_descend(pair, 1).unwrap();
+                IntegerExpression::Literal(int_literal_pair_val(lit_pair).unwrap())
+            }
+            Some("named") => IntegerExpression::NamedConst(pair.as_str().to_owned()),
+            Some("or") => {
+                let mut children = pair.into_inner();
+                let mut or_elems = Vec::with_capacity(children.len());
+                or_elems.push(IntegerExpression::NamedConst(
+                    children.next().unwrap().as_str().to_owned(),
+                ));
+                or_elems.extend(
+                    children
+                        .map(|c| pair_descend(c, 1).unwrap().into())
+                        .flat_map(|e| {
+                            // Flatten or child expressions
+                            if let IntegerExpression::BinaryOr(es) = e {
+                                es.into_iter()
+                            } else {
+                                vec![e].into_iter()
+                            }
+                        }),
+                );
+                IntegerExpression::BinaryOr(or_elems)
+            }
+            _ => unreachable!("{pair:?}"),
+        }
+    }
+}
+
+impl From<Pair<'_, Rule>> for Syscall {
+    fn from(pair: Pair<Rule>) -> Self {
+        let mut subpairs = pair.into_inner();
+        // Note if the grammar is correct, we should *never* panic below
+        let pid = subpairs.next().unwrap().as_str().parse().unwrap();
+        let rel_ts = subpairs.next().unwrap().as_str().parse().unwrap();
+        let name = subpairs.next().unwrap().as_str().to_owned();
+        let args = subpairs
+            .next()
+            .unwrap()
+            .into_inner()
+            .map(|p| {
+                let pair = pair_descend(p, 2).unwrap();
+                SyscallArg::Integer {
+                    value: pair.into(),
+                    metadata: None,
+                }
+            })
+            .collect();
+        let ret_val_pair = pair_descend(subpairs.next().unwrap(), 2).unwrap();
+        let ret_val = int_literal_pair_val(ret_val_pair).unwrap();
+        Syscall {
+            pid,
+            rel_ts,
+            name,
+            args,
+            ret_val,
+        }
+    }
 }