fix for off by one error in file

src/file.rs

@@ -43,11 +43,7 @@ impl<'a, T> Debug for FieldRef<'a, T> {
 
 impl<'a, T> FieldRef<'a, T> {
     fn position_in_source(&self) -> u64 {
-        let record_position = self
-            .file
-            .header
-            .record_position(self.record_index.0)
-            .unwrap() as u64;
+        let record_position = self.file.record_position(self.record_index.0).unwrap() as u64;
         let position_in_record = self.file.fields_info[..self.field_index.0]
             .iter()
             .map(|i| i.field_length as u64)
@@ -195,7 +191,7 @@ impl<'a, T> RecordRef<'a, T> {
     }
 
     fn position_in_source(&self) -> u64 {
-        self.file.header.record_position(self.index.0).unwrap() as u64
+        self.file.record_position(self.index.0).unwrap() as u64
     }
 }
 
@@ -358,6 +354,7 @@ impl<'a, T> FileRecordIterator<'a, T> {
 pub struct File<T> {
     pub(crate) inner: T,
     pub(crate) header: Header,
+    pub(crate) record_length: u16,
     pub(crate) fields_info: Vec<FieldInfo>,
     pub(crate) encoding: DynEncoding,
     /// Non-Memo field length is stored on a u8,
@@ -388,6 +385,17 @@ impl<T> File<T> {
     pub fn set_options(&mut self, options: ReadingOptions) {
         self.options = options;
     }
+
+    pub(crate) fn record_position(&self, index: usize) -> Option<usize> {
+        if index >= self.header.num_records as usize {
+            None
+        } else {
+            let offset = self.header.offset_to_first_record as usize
+                + (index * (self.record_length as usize + DELETION_FLAG_SIZE))
+                + DELETION_FLAG_SIZE;
+            Some(offset)
+        }
+    }
 }
 
 impl<T: Read + Seek> File<T> {
@@ -430,10 +438,14 @@ impl<T: Read + Seek> File<T> {
             let field_error = FieldIOError::new(UnsupportedCodePage(header.code_page_mark), None);
             Error::new(field_error, 0)
         })?;
+
+        let record_length = fields_info.iter().map(|x| x.length() as u16).sum();
+
         Ok(Self {
             inner: source,
             // memo_reader: None,
             header,
+            record_length,
             fields_info,
             encoding,
             field_data_buffer: [0u8; 255],
@@ -470,9 +482,16 @@ impl<T: Write + Seek> File<T> {
     pub fn create_new(mut dst: T, table_info: TableInfo) -> Result<Self, Error> {
         write_header_parts(&mut dst, &table_info.header, &table_info.fields_info)?;
 
+        let record_length = table_info
+            .fields_info
+            .iter()
+            .map(|x| x.field_length as u16)
+            .sum();
+
         Ok(Self {
             inner: dst,
             header: table_info.header,
+            record_length: record_length,
             fields_info: table_info.fields_info,
             encoding: table_info.encoding,
             field_data_buffer: [0u8; 255],
@@ -501,8 +520,7 @@ impl<T: Write + Seek> File<T> {
         );
 
         let end_of_last_record = self.header.offset_to_first_record as u64
-            + self.num_records() as u64
-                * (DELETION_FLAG_SIZE as u64 + self.header.size_of_record as u64);
+            + self.num_records() as u64 * (DELETION_FLAG_SIZE as u64 + self.record_length as u64);
         self.inner
             .seek(SeekFrom::Start(end_of_last_record))
             .map_err(|error| Error::io_error(error, self.num_records()))?;

src/header.rs

@@ -4,7 +4,6 @@ use crate::encoding::DynEncoding;
 use std::io::{Read, Write};
 
 use crate::field::types::Date;
-use crate::field::DELETION_FLAG_SIZE;
 use crate::memo::MemoFileType;
 
 // Used this as source: https://blog.codetitans.pl/post/dbf-and-language-code-page/
@@ -407,17 +406,6 @@ impl Header {
         dest.write_u8(0)?;
         Ok(())
     }
-
-    pub(crate) fn record_position(&self, index: usize) -> Option<usize> {
-        if index >= self.num_records as usize {
-            None
-        } else {
-            let offset = self.offset_to_first_record as usize
-                + (index * (self.size_of_record as usize + DELETION_FLAG_SIZE))
-                + DELETION_FLAG_SIZE;
-            Some(offset)
-        }
-    }
 }
 
 #[cfg(test)]

src/reading.rs

@@ -152,6 +152,7 @@ impl<T: Read + Seek, E: Encoding + 'static> ReaderBuilder<T, E> {
             source: file.inner,
             memo_reader,
             header: file.header,
+            record_length: file.record_length,
             fields_info: file.fields_info,
             encoding: self
                 .encoding
@@ -171,6 +172,7 @@ pub struct Reader<T: Read + Seek> {
     memo_reader: Option<MemoReader<T>>,
     header: Header,
     fields_info: Vec<FieldInfo>,
+    record_length: u16,
     encoding: DynEncoding,
     options: ReadingOptions,
 }
@@ -208,6 +210,7 @@ impl<T: Read + Seek> Reader<T> {
             source: file.inner,
             memo_reader: None,
             header: file.header,
+            record_length: file.record_length,
             fields_info: file.fields_info,
             encoding: file.encoding,
             options: ReadingOptions::default(),
@@ -243,16 +246,12 @@ impl<T: Read + Seek> Reader<T> {
 
     /// Creates an iterator of records of the type you want
     pub fn iter_records_as<R: ReadableRecord>(&mut self) -> RecordIterator<T, R> {
-        let record_size: usize = self
-            .fields_info
-            .iter()
-            .map(|i| i.field_length as usize)
-            .sum();
+        let record_length = self.record_length as usize;
         RecordIterator {
             reader: self,
             record_type: std::marker::PhantomData,
             current_record: 0,
-            record_data_buffer: std::io::Cursor::new(vec![0u8; record_size]),
+            record_data_buffer: std::io::Cursor::new(vec![0u8; record_length]),
             field_data_buffer: [0u8; 255],
         }
     }
@@ -289,8 +288,8 @@ impl<T: Read + Seek> Reader<T> {
 
     /// Seek to the start of the record at `index`
     pub fn seek(&mut self, index: usize) -> Result<(), Error> {
-        let offset = self.header.offset_to_first_record as usize
-            + (index * self.header.size_of_record as usize);
+        let offset =
+            self.header.offset_to_first_record as usize + (index * self.record_length as usize);
         self.source
             .seek(SeekFrom::Start(offset as u64))
             .map_err(|err| Error::io_error(err, 0))?;