Improve creation of error messages

src/Tools/psxcdgen_ex/src/encoder/psx.rs

@@ -2,7 +2,7 @@ use super::{*, SectorWriter, {CDDesc, Error}};
 use super::super::types::{helper::{DirectoryRecordMember, PathTableMember}, layout::Layout, *};
 use builder::SubModeBuilder;
 use cdtypes::types::{cdstring::{AString, DString}, date::*, dir_record::*, helper::{round_bytes_mode2_form1, sector_count_mode2_form1}, path_table::*, pvd as cd_pvd, lsb_msb::*, sector::Mode2Form1};
-use tool_helper::{BufferedInputFile, open_input_file_buffered};
+use tool_helper::{BufferedInputFile, construct_from_error_if as format_if_error, open_input_file_buffered};
 use std::io::{Read, Seek, SeekFrom};
 
 const ROOT_DIR_NAME:&'static str     = "\x00";
@@ -159,8 +159,8 @@ fn process_system_area(system_area: &SystemArea, sec_writer: &mut dyn SectorWrit
         return Err(Error::from_text(format!("System Area required to start at sector 0 of Track - found LBA: {}", system_area_lba)));
     }
 
-    if let Some(license_file) = &system_area.license_file_path {
+    if let Some(license_path) = &system_area.license_file_path {
-        let license_file = open_input_file_buffered(license_file)?;
+        let license_file = format_if_error!(open_input_file_buffered(license_path), "Loading license file from {} failed with: {error_text}", license_path.to_string_lossy())?;
         write_license_file(sec_writer, license_file)    
     }
     

src/Tools/tool_helper/src/lib.rs

@@ -7,6 +7,20 @@ pub type BufferedInputFile = BufReader<std::fs::File>;
 pub type Output            = Box<dyn Write>;
 pub type Input             = Box<dyn Read>;
 
+#[macro_export]
+macro_rules! construct_from_error_if {
+    ($result:expr, $format_text:literal) => {
+        tool_helper::callback_if_error($result, |error_text| {
+            format!($format_text, error_text=error_text)
+        })
+    };
+    ($result:expr, $format_text:literal, $($arg:expr)*) => {
+        tool_helper::callback_if_error($result, |error_text| {
+            format!($format_text, $($arg),*, error_text=error_text)
+        })
+    };
+}
+
 pub trait ErrorString {
     fn to_string(self) -> String;
 }
@@ -101,6 +115,30 @@ impl<T: ErrorString> std::convert::From<T> for Error {
     }
 }
 
+pub fn prefix_if_error<T>(prefix: &str, result: Result<T, Error>) -> Result<T, Error> {
+    match result {
+        Ok(value)      => Ok(value),
+        Err(mut error) => {
+            let mut new_text = String::from(prefix);
+
+            new_text.push_str(error.text.as_str());
+            error.text = new_text;
+            Err(error)
+        },
+    }
+}
+
+pub fn callback_if_error<F: Fn(String) -> String, T>(result: Result<T, Error>, callback: F) -> Result<T, Error> {
+    match result {
+        Ok(value)      => Ok(value),
+        Err(mut error) => {
+            error.text = callback(error.text);
+
+            Err(error)
+        }
+    }
+}
+
 pub fn open_output_file(output_path: &PathBuf) -> Result<BufWriter<std::fs::File>, Error> {
     Ok(std::io::BufWriter::new(std::fs::File::create(output_path)?))
 }