Added file_utils to print not-found path in error (#349)

stwo_cairo_prover/crates/prover/src/input/vm_import/mod.rs

@@ -9,6 +9,7 @@ use cairo_vm::stdlib::collections::HashMap;
 use cairo_vm::types::builtin_name::BuiltinName;
 use cairo_vm::vm::trace::trace_entry::RelocatedTraceEntry;
 use json::PrivateInput;
+use stwo_cairo_utils::file_utils::{open_file, read_to_string, IoErrorWithPath};
 use thiserror::Error;
 use tracing::{span, Level};
 
@@ -22,7 +23,7 @@ use crate::input::memory::MemoryBuilder;
 #[derive(Debug, Error)]
 pub enum VmImportError {
     #[error("IO error: {0}")]
-    Io(#[from] std::io::Error),
+    Io(#[from] IoErrorWithPath),
     #[error("JSON error: {0}")]
     Json(#[from] serde_json::Error),
     #[error("No memory segments")]
@@ -37,10 +38,10 @@ pub fn adapt_vm_output(
     dev_mode: bool,
 ) -> Result<ProverInput, VmImportError> {
     let _span = span!(Level::INFO, "adapt_vm_output").entered();
-    let public_input_string = std::fs::read_to_string(public_input_json)?;
+    let public_input_string = read_to_string(public_input_json)?;
     let public_input: PublicInput<'_> = serde_json::from_str(&public_input_string)?;
-    let private_input: PrivateInput =
-        serde_json::from_str(&std::fs::read_to_string(private_input_json)?)?;
+
+    let private_input: PrivateInput = serde_json::from_reader(&open_file(private_input_json)?)?;
 
     let end_addr = public_input
         .memory_segments
@@ -59,8 +60,8 @@ pub fn adapt_vm_output(
         .unwrap()
         .join(&private_input.trace_path);
 
-    let mut memory_file = std::io::BufReader::new(std::fs::File::open(memory_path)?);
-    let mut trace_file = std::io::BufReader::new(std::fs::File::open(trace_path)?);
+    let mut memory_file = std::io::BufReader::new(open_file(memory_path.as_path())?);
+    let mut trace_file = std::io::BufReader::new(open_file(trace_path.as_path())?);
 
     let public_memory_addresses = public_input
         .public_memory

stwo_cairo_prover/crates/utils/Cargo.toml

@@ -11,3 +11,4 @@ log.workspace = true
 thiserror.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true
+serde.workspace = true

stwo_cairo_prover/crates/utils/src/file_utils.rs

@@ -0,0 +1,36 @@
+use std::fs::File;
+use std::io;
+use std::path::{Path, PathBuf};
+
+/// An extension error to the io:Error, additionally specifying the not-found path.
+#[derive(std::fmt::Debug)]
+pub struct IoErrorWithPath {
+    source: io::Error,
+    path: PathBuf,
+}
+impl std::error::Error for IoErrorWithPath {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        Some(&self.source)
+    }
+}
+impl std::fmt::Display for IoErrorWithPath {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        writeln!(f, "{}: {}", self.source, self.path.display())
+    }
+}
+
+/// A wrapper to `File::open`, which, in case of failure, also logs the not-found path.
+pub fn open_file(path: &Path) -> Result<File, IoErrorWithPath> {
+    File::open(path).map_err(|e| IoErrorWithPath {
+        source: e,
+        path: path.to_path_buf(),
+    })
+}
+
+/// A wrapper to `std::fs::read_to_string`, which, in case of failure, also logs the not-found path.
+pub fn read_to_string(path: &Path) -> Result<String, IoErrorWithPath> {
+    std::fs::read_to_string(path).map_err(|e| IoErrorWithPath {
+        source: e,
+        path: path.to_path_buf(),
+    })
+}

stwo_cairo_prover/crates/utils/src/lib.rs

@@ -1,3 +1,4 @@
 pub mod binary_utils;
+pub mod file_utils;
 pub mod logging_utils;
 pub mod vm_utils;