Improved error message when buffer exceeds #52

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased] - 2021-??-??
 ### Changed
 - Small code improvement for writing field separators
+- Improved error message when buffer exceeds (because of invalid CSV data) [\#52](https://github.com/osiegmar/FastCSV/issues/52)
 
 ## [2.0.0] - 2021-01-01
 ### Added

config/checkstyle/checkstyle.xml

@@ -65,7 +65,7 @@
     -->
 
     <module name="LineLength">
-        <property name="max" value="100"/>
+        <property name="max" value="120"/>
         <property name="ignorePattern" value="^package.*|^import.*|a href|href|http://|https://|ftp://"/>
     </module>
 

src/main/java/de/siegmar/fastcsv/reader/CsvReader.java

@@ -187,7 +187,12 @@ private void fetch() {
             try {
                 fetchedRow = fetchRow();
             } catch (final IOException e) {
-                throw new UncheckedIOException(e);
+                if (fetchedRow != null) {
+                    throw new UncheckedIOException("IOException when reading record that started in line "
+                        + (fetchedRow.getOriginalLineNumber() + 1), e);
+                } else {
+                    throw new UncheckedIOException("IOException when reading first record", e);
+                }
             }
             fetched = true;
         }

src/main/java/de/siegmar/fastcsv/reader/RowReader.java

@@ -297,8 +297,9 @@ private static char[] extendAndRelocate(final char[] buf, final int begin)
 
             final int newBufferSize = buf.length * 2;
             if (newBufferSize > MAX_BUFFER_SIZE) {
-                throw new IOException("Maximum buffer size "
-                    + MAX_BUFFER_SIZE + " is not enough to read data");
+                throw new IOException("Maximum buffer size " + MAX_BUFFER_SIZE + " is not enough "
+                    + "to read data of a single field. Typically, this happens if quotation "
+                    + "started but did not end within this buffer's maximum boundary.");
             }
             final char[] newBuf = new char[newBufferSize];
             System.arraycopy(buf, begin, newBuf, 0, buf.length - begin);

src/test/java/blackbox/reader/CsvReaderTest.java

@@ -1,16 +1,14 @@
 package blackbox.reader;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.io.ByteArrayInputStream;
+import java.io.CharArrayReader;
 import java.io.IOException;
-import java.io.InputStreamReader;
 import java.io.StringReader;
 import java.io.UncheckedIOException;
 import java.util.Arrays;
@@ -258,19 +256,41 @@ public void toStringWithoutHeader() {
 
     @Test
     public void bufferExceed() {
-        final byte[] buf = new byte[8 * 1024 * 1024];
-        Arrays.fill(buf, (byte) 'a');
-        buf[buf.length - 1] = (byte) ',';
+        final char[] buf = new char[8 * 1024 * 1024];
+        Arrays.fill(buf, 'X');
+        buf[buf.length - 1] = ',';
 
-        crb.build(new InputStreamReader(new ByteArrayInputStream(buf), UTF_8))
-            .iterator().next();
+        crb.build(new CharArrayReader(buf)).iterator().next();
 
-        buf[buf.length - 1] = (byte) 'a';
+        buf[buf.length - 1] = (byte) 'X';
         final UncheckedIOException exception = assertThrows(UncheckedIOException.class, () ->
-            crb.build(new InputStreamReader(new ByteArrayInputStream(buf), UTF_8))
-                .iterator().next());
-        assertEquals("java.io.IOException: Maximum buffer size 8388608 is not enough to read data",
-            exception.getMessage());
+            crb.build(new CharArrayReader(buf)).iterator().next());
+        assertEquals("IOException when reading first record", exception.getMessage());
+
+        assertEquals("Maximum buffer size 8388608 is not enough to read data of a single field. "
+                + "Typically, this happens if quotation started but did not end within this buffer's "
+                + "maximum boundary.",
+            exception.getCause().getMessage());
+    }
+
+    @Test
+    public void bufferExceedSubsequentRecord() {
+        final char[] buf = new char[8 * 1024 * 1024];
+        Arrays.fill(buf, 'X');
+        final String s = "a,b,c\n\"";
+        System.arraycopy(s.toCharArray(), 0, buf, 0, s.length());
+
+        final CloseableIterator<CsvRow> iterator = crb.build(new CharArrayReader(buf)).iterator();
+
+        iterator.next();
+
+        final UncheckedIOException exception = assertThrows(UncheckedIOException.class, iterator::next);
+        assertEquals("IOException when reading record that started in line 2", exception.getMessage());
+
+        assertEquals("Maximum buffer size 8388608 is not enough to read data of a single field. "
+                + "Typically, this happens if quotation started but did not end within this buffer's "
+                + "maximum boundary.",
+            exception.getCause().getMessage());
     }
 
     // API
@@ -342,7 +362,7 @@ public void unreadable() {
         final UncheckedIOException e = assertThrows(UncheckedIOException.class, () ->
             crb.build(new UnreadableReader()).iterator().next());
 
-        assertEquals("java.io.IOException: Cannot read", e.getMessage());
+        assertEquals("IOException when reading first record", e.getMessage());
     }
 
     // test helpers