Adding upstream version 1.16.10.upstream/1.16.10upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

6 files changed, 1404 insertions, 0 deletions

diff --git a/src/encoding/csv/example_test.go b/src/encoding/csv/example_test.go
new file mode 100644
index 0000000..dc227d4
--- /dev/null
+++ b/src/encoding/csv/example_test.go
@@ -0,0 +1,131 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package csv_test
+
+import (
+	"encoding/csv"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+)
+
+func ExampleReader() {
+	in := `first_name,last_name,username
+"Rob","Pike",rob
+Ken,Thompson,ken
+"Robert","Griesemer","gri"
+`
+	r := csv.NewReader(strings.NewReader(in))
+
+	for {
+		record, err := r.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			log.Fatal(err)
+		}
+
+		fmt.Println(record)
+	}
+	// Output:
+	// [first_name last_name username]
+	// [Rob Pike rob]
+	// [Ken Thompson ken]
+	// [Robert Griesemer gri]
+}
+
+// This example shows how csv.Reader can be configured to handle other
+// types of CSV files.
+func ExampleReader_options() {
+	in := `first_name;last_name;username
+"Rob";"Pike";rob
+# lines beginning with a # character are ignored
+Ken;Thompson;ken
+"Robert";"Griesemer";"gri"
+`
+	r := csv.NewReader(strings.NewReader(in))
+	r.Comma = ';'
+	r.Comment = '#'
+
+	records, err := r.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Print(records)
+	// Output:
+	// [[first_name last_name username] [Rob Pike rob] [Ken Thompson ken] [Robert Griesemer gri]]
+}
+
+func ExampleReader_ReadAll() {
+	in := `first_name,last_name,username
+"Rob","Pike",rob
+Ken,Thompson,ken
+"Robert","Griesemer","gri"
+`
+	r := csv.NewReader(strings.NewReader(in))
+
+	records, err := r.ReadAll()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Print(records)
+	// Output:
+	// [[first_name last_name username] [Rob Pike rob] [Ken Thompson ken] [Robert Griesemer gri]]
+}
+
+func ExampleWriter() {
+	records := [][]string{
+		{"first_name", "last_name", "username"},
+		{"Rob", "Pike", "rob"},
+		{"Ken", "Thompson", "ken"},
+		{"Robert", "Griesemer", "gri"},
+	}
+
+	w := csv.NewWriter(os.Stdout)
+
+	for _, record := range records {
+		if err := w.Write(record); err != nil {
+			log.Fatalln("error writing record to csv:", err)
+		}
+	}
+
+	// Write any buffered data to the underlying writer (standard output).
+	w.Flush()
+
+	if err := w.Error(); err != nil {
+		log.Fatal(err)
+	}
+	// Output:
+	// first_name,last_name,username
+	// Rob,Pike,rob
+	// Ken,Thompson,ken
+	// Robert,Griesemer,gri
+}
+
+func ExampleWriter_WriteAll() {
+	records := [][]string{
+		{"first_name", "last_name", "username"},
+		{"Rob", "Pike", "rob"},
+		{"Ken", "Thompson", "ken"},
+		{"Robert", "Griesemer", "gri"},
+	}
+
+	w := csv.NewWriter(os.Stdout)
+	w.WriteAll(records) // calls Flush internally
+
+	if err := w.Error(); err != nil {
+		log.Fatalln("error writing csv:", err)
+	}
+	// Output:
+	// first_name,last_name,username
+	// Rob,Pike,rob
+	// Ken,Thompson,ken
+	// Robert,Griesemer,gri
+}
diff --git a/src/encoding/csv/fuzz.go b/src/encoding/csv/fuzz.go
new file mode 100644
index 0000000..8be21d5
--- /dev/null
+++ b/src/encoding/csv/fuzz.go
@@ -0,0 +1,70 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build gofuzz
+
+package csv
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+)
+
+func Fuzz(data []byte) int {
+	score := 0
+	buf := new(bytes.Buffer)
+
+	for _, tt := range []Reader{
+		{},
+		{Comma: ';'},
+		{Comma: '\t'},
+		{LazyQuotes: true},
+		{TrimLeadingSpace: true},
+		{Comment: '#'},
+		{Comment: ';'},
+	} {
+		r := NewReader(bytes.NewReader(data))
+		r.Comma = tt.Comma
+		r.Comment = tt.Comment
+		r.LazyQuotes = tt.LazyQuotes
+		r.TrimLeadingSpace = tt.TrimLeadingSpace
+
+		records, err := r.ReadAll()
+		if err != nil {
+			continue
+		}
+		score = 1
+
+		buf.Reset()
+		w := NewWriter(buf)
+		w.Comma = tt.Comma
+		err = w.WriteAll(records)
+		if err != nil {
+			fmt.Printf("writer  = %#v\n", w)
+			fmt.Printf("records = %v\n", records)
+			panic(err)
+		}
+
+		r = NewReader(buf)
+		r.Comma = tt.Comma
+		r.Comment = tt.Comment
+		r.LazyQuotes = tt.LazyQuotes
+		r.TrimLeadingSpace = tt.TrimLeadingSpace
+		result, err := r.ReadAll()
+		if err != nil {
+			fmt.Printf("reader  = %#v\n", r)
+			fmt.Printf("records = %v\n", records)
+			panic(err)
+		}
+
+		if !reflect.DeepEqual(records, result) {
+			fmt.Println("records = \n", records)
+			fmt.Println("result  = \n", records)
+			panic("not equal")
+		}
+	}
+
+	return score
+}
diff --git a/src/encoding/csv/reader.go b/src/encoding/csv/reader.go
new file mode 100644
index 0000000..c40aa50
--- /dev/null
+++ b/src/encoding/csv/reader.go
@@ -0,0 +1,401 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package csv reads and writes comma-separated values (CSV) files.
+// There are many kinds of CSV files; this package supports the format
+// described in RFC 4180.
+//
+// A csv file contains zero or more records of one or more fields per record.
+// Each record is separated by the newline character. The final record may
+// optionally be followed by a newline character.
+//
+//	field1,field2,field3
+//
+// White space is considered part of a field.
+//
+// Carriage returns before newline characters are silently removed.
+//
+// Blank lines are ignored. A line with only whitespace characters (excluding
+// the ending newline character) is not considered a blank line.
+//
+// Fields which start and stop with the quote character " are called
+// quoted-fields. The beginning and ending quote are not part of the
+// field.
+//
+// The source:
+//
+//	normal string,"quoted-field"
+//
+// results in the fields
+//
+//	{`normal string`, `quoted-field`}
+//
+// Within a quoted-field a quote character followed by a second quote
+// character is considered a single quote.
+//
+//	"the ""word"" is true","a ""quoted-field"""
+//
+// results in
+//
+//	{`the "word" is true`, `a "quoted-field"`}
+//
+// Newlines and commas may be included in a quoted-field
+//
+//	"Multi-line
+//	field","comma is ,"
+//
+// results in
+//
+//	{`Multi-line
+//	field`, `comma is ,`}
+package csv
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"unicode"
+	"unicode/utf8"
+)
+
+// A ParseError is returned for parsing errors.
+// Line numbers are 1-indexed and columns are 0-indexed.
+type ParseError struct {
+	StartLine int   // Line where the record starts
+	Line      int   // Line where the error occurred
+	Column    int   // Column (rune index) where the error occurred
+	Err       error // The actual error
+}
+
+func (e *ParseError) Error() string {
+	if e.Err == ErrFieldCount {
+		return fmt.Sprintf("record on line %d: %v", e.Line, e.Err)
+	}
+	if e.StartLine != e.Line {
+		return fmt.Sprintf("record on line %d; parse error on line %d, column %d: %v", e.StartLine, e.Line, e.Column, e.Err)
+	}
+	return fmt.Sprintf("parse error on line %d, column %d: %v", e.Line, e.Column, e.Err)
+}
+
+func (e *ParseError) Unwrap() error { return e.Err }
+
+// These are the errors that can be returned in ParseError.Err.
+var (
+	ErrTrailingComma = errors.New("extra delimiter at end of line") // Deprecated: No longer used.
+	ErrBareQuote     = errors.New("bare \" in non-quoted-field")
+	ErrQuote         = errors.New("extraneous or missing \" in quoted-field")
+	ErrFieldCount    = errors.New("wrong number of fields")
+)
+
+var errInvalidDelim = errors.New("csv: invalid field or comment delimiter")
+
+func validDelim(r rune) bool {
+	return r != 0 && r != '"' && r != '\r' && r != '\n' && utf8.ValidRune(r) && r != utf8.RuneError
+}
+
+// A Reader reads records from a CSV-encoded file.
+//
+// As returned by NewReader, a Reader expects input conforming to RFC 4180.
+// The exported fields can be changed to customize the details before the
+// first call to Read or ReadAll.
+//
+// The Reader converts all \r\n sequences in its input to plain \n,
+// including in multiline field values, so that the returned data does
+// not depend on which line-ending convention an input file uses.
+type Reader struct {
+	// Comma is the field delimiter.
+	// It is set to comma (',') by NewReader.
+	// Comma must be a valid rune and must not be \r, \n,
+	// or the Unicode replacement character (0xFFFD).
+	Comma rune
+
+	// Comment, if not 0, is the comment character. Lines beginning with the
+	// Comment character without preceding whitespace are ignored.
+	// With leading whitespace the Comment character becomes part of the
+	// field, even if TrimLeadingSpace is true.
+	// Comment must be a valid rune and must not be \r, \n,
+	// or the Unicode replacement character (0xFFFD).
+	// It must also not be equal to Comma.
+	Comment rune
+
+	// FieldsPerRecord is the number of expected fields per record.
+	// If FieldsPerRecord is positive, Read requires each record to
+	// have the given number of fields. If FieldsPerRecord is 0, Read sets it to
+	// the number of fields in the first record, so that future records must
+	// have the same field count. If FieldsPerRecord is negative, no check is
+	// made and records may have a variable number of fields.
+	FieldsPerRecord int
+
+	// If LazyQuotes is true, a quote may appear in an unquoted field and a
+	// non-doubled quote may appear in a quoted field.
+	LazyQuotes bool
+
+	// If TrimLeadingSpace is true, leading white space in a field is ignored.
+	// This is done even if the field delimiter, Comma, is white space.
+	TrimLeadingSpace bool
+
+	// ReuseRecord controls whether calls to Read may return a slice sharing
+	// the backing array of the previous call's returned slice for performance.
+	// By default, each call to Read returns newly allocated memory owned by the caller.
+	ReuseRecord bool
+
+	TrailingComma bool // Deprecated: No longer used.
+
+	r *bufio.Reader
+
+	// numLine is the current line being read in the CSV file.
+	numLine int
+
+	// rawBuffer is a line buffer only used by the readLine method.
+	rawBuffer []byte
+
+	// recordBuffer holds the unescaped fields, one after another.
+	// The fields can be accessed by using the indexes in fieldIndexes.
+	// E.g., For the row `a,"b","c""d",e`, recordBuffer will contain `abc"de`
+	// and fieldIndexes will contain the indexes [1, 2, 5, 6].
+	recordBuffer []byte
+
+	// fieldIndexes is an index of fields inside recordBuffer.
+	// The i'th field ends at offset fieldIndexes[i] in recordBuffer.
+	fieldIndexes []int
+
+	// lastRecord is a record cache and only used when ReuseRecord == true.
+	lastRecord []string
+}
+
+// NewReader returns a new Reader that reads from r.
+func NewReader(r io.Reader) *Reader {
+	return &Reader{
+		Comma: ',',
+		r:     bufio.NewReader(r),
+	}
+}
+
+// Read reads one record (a slice of fields) from r.
+// If the record has an unexpected number of fields,
+// Read returns the record along with the error ErrFieldCount.
+// Except for that case, Read always returns either a non-nil
+// record or a non-nil error, but not both.
+// If there is no data left to be read, Read returns nil, io.EOF.
+// If ReuseRecord is true, the returned slice may be shared
+// between multiple calls to Read.
+func (r *Reader) Read() (record []string, err error) {
+	if r.ReuseRecord {
+		record, err = r.readRecord(r.lastRecord)
+		r.lastRecord = record
+	} else {
+		record, err = r.readRecord(nil)
+	}
+	return record, err
+}
+
+// ReadAll reads all the remaining records from r.
+// Each record is a slice of fields.
+// A successful call returns err == nil, not err == io.EOF. Because ReadAll is
+// defined to read until EOF, it does not treat end of file as an error to be
+// reported.
+func (r *Reader) ReadAll() (records [][]string, err error) {
+	for {
+		record, err := r.readRecord(nil)
+		if err == io.EOF {
+			return records, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+		records = append(records, record)
+	}
+}
+
+// readLine reads the next line (with the trailing endline).
+// If EOF is hit without a trailing endline, it will be omitted.
+// If some bytes were read, then the error is never io.EOF.
+// The result is only valid until the next call to readLine.
+func (r *Reader) readLine() ([]byte, error) {
+	line, err := r.r.ReadSlice('\n')
+	if err == bufio.ErrBufferFull {
+		r.rawBuffer = append(r.rawBuffer[:0], line...)
+		for err == bufio.ErrBufferFull {
+			line, err = r.r.ReadSlice('\n')
+			r.rawBuffer = append(r.rawBuffer, line...)
+		}
+		line = r.rawBuffer
+	}
+	if len(line) > 0 && err == io.EOF {
+		err = nil
+		// For backwards compatibility, drop trailing \r before EOF.
+		if line[len(line)-1] == '\r' {
+			line = line[:len(line)-1]
+		}
+	}
+	r.numLine++
+	// Normalize \r\n to \n on all input lines.
+	if n := len(line); n >= 2 && line[n-2] == '\r' && line[n-1] == '\n' {
+		line[n-2] = '\n'
+		line = line[:n-1]
+	}
+	return line, err
+}
+
+// lengthNL reports the number of bytes for the trailing \n.
+func lengthNL(b []byte) int {
+	if len(b) > 0 && b[len(b)-1] == '\n' {
+		return 1
+	}
+	return 0
+}
+
+// nextRune returns the next rune in b or utf8.RuneError.
+func nextRune(b []byte) rune {
+	r, _ := utf8.DecodeRune(b)
+	return r
+}
+
+func (r *Reader) readRecord(dst []string) ([]string, error) {
+	if r.Comma == r.Comment || !validDelim(r.Comma) || (r.Comment != 0 && !validDelim(r.Comment)) {
+		return nil, errInvalidDelim
+	}
+
+	// Read line (automatically skipping past empty lines and any comments).
+	var line, fullLine []byte
+	var errRead error
+	for errRead == nil {
+		line, errRead = r.readLine()
+		if r.Comment != 0 && nextRune(line) == r.Comment {
+			line = nil
+			continue // Skip comment lines
+		}
+		if errRead == nil && len(line) == lengthNL(line) {
+			line = nil
+			continue // Skip empty lines
+		}
+		fullLine = line
+		break
+	}
+	if errRead == io.EOF {
+		return nil, errRead
+	}
+
+	// Parse each field in the record.
+	var err error
+	const quoteLen = len(`"`)
+	commaLen := utf8.RuneLen(r.Comma)
+	recLine := r.numLine // Starting line for record
+	r.recordBuffer = r.recordBuffer[:0]
+	r.fieldIndexes = r.fieldIndexes[:0]
+parseField:
+	for {
+		if r.TrimLeadingSpace {
+			line = bytes.TrimLeftFunc(line, unicode.IsSpace)
+		}
+		if len(line) == 0 || line[0] != '"' {
+			// Non-quoted string field
+			i := bytes.IndexRune(line, r.Comma)
+			field := line
+			if i >= 0 {
+				field = field[:i]
+			} else {
+				field = field[:len(field)-lengthNL(field)]
+			}
+			// Check to make sure a quote does not appear in field.
+			if !r.LazyQuotes {
+				if j := bytes.IndexByte(field, '"'); j >= 0 {
+					col := utf8.RuneCount(fullLine[:len(fullLine)-len(line[j:])])
+					err = &ParseError{StartLine: recLine, Line: r.numLine, Column: col, Err: ErrBareQuote}
+					break parseField
+				}
+			}
+			r.recordBuffer = append(r.recordBuffer, field...)
+			r.fieldIndexes = append(r.fieldIndexes, len(r.recordBuffer))
+			if i >= 0 {
+				line = line[i+commaLen:]
+				continue parseField
+			}
+			break parseField
+		} else {
+			// Quoted string field
+			line = line[quoteLen:]
+			for {
+				i := bytes.IndexByte(line, '"')
+				if i >= 0 {
+					// Hit next quote.
+					r.recordBuffer = append(r.recordBuffer, line[:i]...)
+					line = line[i+quoteLen:]
+					switch rn := nextRune(line); {
+					case rn == '"':
+						// `""` sequence (append quote).
+						r.recordBuffer = append(r.recordBuffer, '"')
+						line = line[quoteLen:]
+					case rn == r.Comma:
+						// `",` sequence (end of field).
+						line = line[commaLen:]
+						r.fieldIndexes = append(r.fieldIndexes, len(r.recordBuffer))
+						continue parseField
+					case lengthNL(line) == len(line):
+						// `"\n` sequence (end of line).
+						r.fieldIndexes = append(r.fieldIndexes, len(r.recordBuffer))
+						break parseField
+					case r.LazyQuotes:
+						// `"` sequence (bare quote).
+						r.recordBuffer = append(r.recordBuffer, '"')
+					default:
+						// `"*` sequence (invalid non-escaped quote).
+						col := utf8.RuneCount(fullLine[:len(fullLine)-len(line)-quoteLen])
+						err = &ParseError{StartLine: recLine, Line: r.numLine, Column: col, Err: ErrQuote}
+						break parseField
+					}
+				} else if len(line) > 0 {
+					// Hit end of line (copy all data so far).
+					r.recordBuffer = append(r.recordBuffer, line...)
+					if errRead != nil {
+						break parseField
+					}
+					line, errRead = r.readLine()
+					if errRead == io.EOF {
+						errRead = nil
+					}
+					fullLine = line
+				} else {
+					// Abrupt end of file (EOF or error).
+					if !r.LazyQuotes && errRead == nil {
+						col := utf8.RuneCount(fullLine)
+						err = &ParseError{StartLine: recLine, Line: r.numLine, Column: col, Err: ErrQuote}
+						break parseField
+					}
+					r.fieldIndexes = append(r.fieldIndexes, len(r.recordBuffer))
+					break parseField
+				}
+			}
+		}
+	}
+	if err == nil {
+		err = errRead
+	}
+
+	// Create a single string and create slices out of it.
+	// This pins the memory of the fields together, but allocates once.
+	str := string(r.recordBuffer) // Convert to string once to batch allocations
+	dst = dst[:0]
+	if cap(dst) < len(r.fieldIndexes) {
+		dst = make([]string, len(r.fieldIndexes))
+	}
+	dst = dst[:len(r.fieldIndexes)]
+	var preIdx int
+	for i, idx := range r.fieldIndexes {
+		dst[i] = str[preIdx:idx]
+		preIdx = idx
+	}
+
+	// Check or update the expected fields per record.
+	if r.FieldsPerRecord > 0 {
+		if len(dst) != r.FieldsPerRecord && err == nil {
+			err = &ParseError{StartLine: recLine, Line: recLine, Err: ErrFieldCount}
+		}
+	} else if r.FieldsPerRecord == 0 {
+		r.FieldsPerRecord = len(dst)
+	}
+	return dst, err
+}
diff --git a/src/encoding/csv/reader_test.go b/src/encoding/csv/reader_test.go
new file mode 100644
index 0000000..5121791
--- /dev/null
+++ b/src/encoding/csv/reader_test.go
@@ -0,0 +1,509 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package csv
+
+import (
+	"io"
+	"reflect"
+	"strings"
+	"testing"
+	"unicode/utf8"
+)
+
+func TestRead(t *testing.T) {
+	tests := []struct {
+		Name   string
+		Input  string
+		Output [][]string
+		Error  error
+
+		// These fields are copied into the Reader
+		Comma              rune
+		Comment            rune
+		UseFieldsPerRecord bool // false (default) means FieldsPerRecord is -1
+		FieldsPerRecord    int
+		LazyQuotes         bool
+		TrimLeadingSpace   bool
+		ReuseRecord        bool
+	}{{
+		Name:   "Simple",
+		Input:  "a,b,c\n",
+		Output: [][]string{{"a", "b", "c"}},
+	}, {
+		Name:   "CRLF",
+		Input:  "a,b\r\nc,d\r\n",
+		Output: [][]string{{"a", "b"}, {"c", "d"}},
+	}, {
+		Name:   "BareCR",
+		Input:  "a,b\rc,d\r\n",
+		Output: [][]string{{"a", "b\rc", "d"}},
+	}, {
+		Name: "RFC4180test",
+		Input: `#field1,field2,field3
+"aaa","bb
+b","ccc"
+"a,a","b""bb","ccc"
+zzz,yyy,xxx
+`,
+		Output: [][]string{
+			{"#field1", "field2", "field3"},
+			{"aaa", "bb\nb", "ccc"},
+			{"a,a", `b"bb`, "ccc"},
+			{"zzz", "yyy", "xxx"},
+		},
+		UseFieldsPerRecord: true,
+		FieldsPerRecord:    0,
+	}, {
+		Name:   "NoEOLTest",
+		Input:  "a,b,c",
+		Output: [][]string{{"a", "b", "c"}},
+	}, {
+		Name:   "Semicolon",
+		Input:  "a;b;c\n",
+		Output: [][]string{{"a", "b", "c"}},
+		Comma:  ';',
+	}, {
+		Name: "MultiLine",
+		Input: `"two
+line","one line","three
+line
+field"`,
+		Output: [][]string{{"two\nline", "one line", "three\nline\nfield"}},
+	}, {
+		Name:  "BlankLine",
+		Input: "a,b,c\n\nd,e,f\n\n",
+		Output: [][]string{
+			{"a", "b", "c"},
+			{"d", "e", "f"},
+		},
+	}, {
+		Name:  "BlankLineFieldCount",
+		Input: "a,b,c\n\nd,e,f\n\n",
+		Output: [][]string{
+			{"a", "b", "c"},
+			{"d", "e", "f"},
+		},
+		UseFieldsPerRecord: true,
+		FieldsPerRecord:    0,
+	}, {
+		Name:             "TrimSpace",
+		Input:            " a,  b,   c\n",
+		Output:           [][]string{{"a", "b", "c"}},
+		TrimLeadingSpace: true,
+	}, {
+		Name:   "LeadingSpace",
+		Input:  " a,  b,   c\n",
+		Output: [][]string{{" a", "  b", "   c"}},
+	}, {
+		Name:    "Comment",
+		Input:   "#1,2,3\na,b,c\n#comment",
+		Output:  [][]string{{"a", "b", "c"}},
+		Comment: '#',
+	}, {
+		Name:   "NoComment",
+		Input:  "#1,2,3\na,b,c",
+		Output: [][]string{{"#1", "2", "3"}, {"a", "b", "c"}},
+	}, {
+		Name:       "LazyQuotes",
+		Input:      `a "word","1"2",a","b`,
+		Output:     [][]string{{`a "word"`, `1"2`, `a"`, `b`}},
+		LazyQuotes: true,
+	}, {
+		Name:       "BareQuotes",
+		Input:      `a "word","1"2",a"`,
+		Output:     [][]string{{`a "word"`, `1"2`, `a"`}},
+		LazyQuotes: true,
+	}, {
+		Name:       "BareDoubleQuotes",
+		Input:      `a""b,c`,
+		Output:     [][]string{{`a""b`, `c`}},
+		LazyQuotes: true,
+	}, {
+		Name:  "BadDoubleQuotes",
+		Input: `a""b,c`,
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 1, Err: ErrBareQuote},
+	}, {
+		Name:             "TrimQuote",
+		Input:            ` "a"," b",c`,
+		Output:           [][]string{{"a", " b", "c"}},
+		TrimLeadingSpace: true,
+	}, {
+		Name:  "BadBareQuote",
+		Input: `a "word","b"`,
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 2, Err: ErrBareQuote},
+	}, {
+		Name:  "BadTrailingQuote",
+		Input: `"a word",b"`,
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 10, Err: ErrBareQuote},
+	}, {
+		Name:  "ExtraneousQuote",
+		Input: `"a "word","b"`,
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 3, Err: ErrQuote},
+	}, {
+		Name:               "BadFieldCount",
+		Input:              "a,b,c\nd,e",
+		Error:              &ParseError{StartLine: 2, Line: 2, Err: ErrFieldCount},
+		UseFieldsPerRecord: true,
+		FieldsPerRecord:    0,
+	}, {
+		Name:               "BadFieldCount1",
+		Input:              `a,b,c`,
+		Error:              &ParseError{StartLine: 1, Line: 1, Err: ErrFieldCount},
+		UseFieldsPerRecord: true,
+		FieldsPerRecord:    2,
+	}, {
+		Name:   "FieldCount",
+		Input:  "a,b,c\nd,e",
+		Output: [][]string{{"a", "b", "c"}, {"d", "e"}},
+	}, {
+		Name:   "TrailingCommaEOF",
+		Input:  "a,b,c,",
+		Output: [][]string{{"a", "b", "c", ""}},
+	}, {
+		Name:   "TrailingCommaEOL",
+		Input:  "a,b,c,\n",
+		Output: [][]string{{"a", "b", "c", ""}},
+	}, {
+		Name:             "TrailingCommaSpaceEOF",
+		Input:            "a,b,c, ",
+		Output:           [][]string{{"a", "b", "c", ""}},
+		TrimLeadingSpace: true,
+	}, {
+		Name:             "TrailingCommaSpaceEOL",
+		Input:            "a,b,c, \n",
+		Output:           [][]string{{"a", "b", "c", ""}},
+		TrimLeadingSpace: true,
+	}, {
+		Name:             "TrailingCommaLine3",
+		Input:            "a,b,c\nd,e,f\ng,hi,",
+		Output:           [][]string{{"a", "b", "c"}, {"d", "e", "f"}, {"g", "hi", ""}},
+		TrimLeadingSpace: true,
+	}, {
+		Name:   "NotTrailingComma3",
+		Input:  "a,b,c, \n",
+		Output: [][]string{{"a", "b", "c", " "}},
+	}, {
+		Name: "CommaFieldTest",
+		Input: `x,y,z,w
+x,y,z,
+x,y,,
+x,,,
+,,,
+"x","y","z","w"
+"x","y","z",""
+"x","y","",""
+"x","","",""
+"","","",""
+`,
+		Output: [][]string{
+			{"x", "y", "z", "w"},
+			{"x", "y", "z", ""},
+			{"x", "y", "", ""},
+			{"x", "", "", ""},
+			{"", "", "", ""},
+			{"x", "y", "z", "w"},
+			{"x", "y", "z", ""},
+			{"x", "y", "", ""},
+			{"x", "", "", ""},
+			{"", "", "", ""},
+		},
+	}, {
+		Name:  "TrailingCommaIneffective1",
+		Input: "a,b,\nc,d,e",
+		Output: [][]string{
+			{"a", "b", ""},
+			{"c", "d", "e"},
+		},
+		TrimLeadingSpace: true,
+	}, {
+		Name:  "ReadAllReuseRecord",
+		Input: "a,b\nc,d",
+		Output: [][]string{
+			{"a", "b"},
+			{"c", "d"},
+		},
+		ReuseRecord: true,
+	}, {
+		Name:  "StartLine1", // Issue 19019
+		Input: "a,\"b\nc\"d,e",
+		Error: &ParseError{StartLine: 1, Line: 2, Column: 1, Err: ErrQuote},
+	}, {
+		Name:  "StartLine2",
+		Input: "a,b\n\"d\n\n,e",
+		Error: &ParseError{StartLine: 2, Line: 5, Column: 0, Err: ErrQuote},
+	}, {
+		Name:  "CRLFInQuotedField", // Issue 21201
+		Input: "A,\"Hello\r\nHi\",B\r\n",
+		Output: [][]string{
+			{"A", "Hello\nHi", "B"},
+		},
+	}, {
+		Name:   "BinaryBlobField", // Issue 19410
+		Input:  "x09\x41\xb4\x1c,aktau",
+		Output: [][]string{{"x09A\xb4\x1c", "aktau"}},
+	}, {
+		Name:   "TrailingCR",
+		Input:  "field1,field2\r",
+		Output: [][]string{{"field1", "field2"}},
+	}, {
+		Name:   "QuotedTrailingCR",
+		Input:  "\"field\"\r",
+		Output: [][]string{{"field"}},
+	}, {
+		Name:  "QuotedTrailingCRCR",
+		Input: "\"field\"\r\r",
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 6, Err: ErrQuote},
+	}, {
+		Name:   "FieldCR",
+		Input:  "field\rfield\r",
+		Output: [][]string{{"field\rfield"}},
+	}, {
+		Name:   "FieldCRCR",
+		Input:  "field\r\rfield\r\r",
+		Output: [][]string{{"field\r\rfield\r"}},
+	}, {
+		Name:   "FieldCRCRLF",
+		Input:  "field\r\r\nfield\r\r\n",
+		Output: [][]string{{"field\r"}, {"field\r"}},
+	}, {
+		Name:   "FieldCRCRLFCR",
+		Input:  "field\r\r\n\rfield\r\r\n\r",
+		Output: [][]string{{"field\r"}, {"\rfield\r"}},
+	}, {
+		Name:   "FieldCRCRLFCRCR",
+		Input:  "field\r\r\n\r\rfield\r\r\n\r\r",
+		Output: [][]string{{"field\r"}, {"\r\rfield\r"}, {"\r"}},
+	}, {
+		Name:  "MultiFieldCRCRLFCRCR",
+		Input: "field1,field2\r\r\n\r\rfield1,field2\r\r\n\r\r,",
+		Output: [][]string{
+			{"field1", "field2\r"},
+			{"\r\rfield1", "field2\r"},
+			{"\r\r", ""},
+		},
+	}, {
+		Name:             "NonASCIICommaAndComment",
+		Input:            "a£b,c£ \td,e\n€ comment\n",
+		Output:           [][]string{{"a", "b,c", "d,e"}},
+		TrimLeadingSpace: true,
+		Comma:            '£',
+		Comment:          '€',
+	}, {
+		Name:    "NonASCIICommaAndCommentWithQuotes",
+		Input:   "a€\"  b,\"€ c\nλ comment\n",
+		Output:  [][]string{{"a", "  b,", " c"}},
+		Comma:   '€',
+		Comment: 'λ',
+	}, {
+		// λ and θ start with the same byte.
+		// This tests that the parser doesn't confuse such characters.
+		Name:    "NonASCIICommaConfusion",
+		Input:   "\"abθcd\"λefθgh",
+		Output:  [][]string{{"abθcd", "efθgh"}},
+		Comma:   'λ',
+		Comment: '€',
+	}, {
+		Name:    "NonASCIICommentConfusion",
+		Input:   "λ\nλ\nθ\nλ\n",
+		Output:  [][]string{{"λ"}, {"λ"}, {"λ"}},
+		Comment: 'θ',
+	}, {
+		Name:   "QuotedFieldMultipleLF",
+		Input:  "\"\n\n\n\n\"",
+		Output: [][]string{{"\n\n\n\n"}},
+	}, {
+		Name:  "MultipleCRLF",
+		Input: "\r\n\r\n\r\n\r\n",
+	}, {
+		// The implementation may read each line in several chunks if it doesn't fit entirely
+		// in the read buffer, so we should test the code to handle that condition.
+		Name:    "HugeLines",
+		Input:   strings.Repeat("#ignore\n", 10000) + strings.Repeat("@", 5000) + "," + strings.Repeat("*", 5000),
+		Output:  [][]string{{strings.Repeat("@", 5000), strings.Repeat("*", 5000)}},
+		Comment: '#',
+	}, {
+		Name:  "QuoteWithTrailingCRLF",
+		Input: "\"foo\"bar\"\r\n",
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 4, Err: ErrQuote},
+	}, {
+		Name:       "LazyQuoteWithTrailingCRLF",
+		Input:      "\"foo\"bar\"\r\n",
+		Output:     [][]string{{`foo"bar`}},
+		LazyQuotes: true,
+	}, {
+		Name:   "DoubleQuoteWithTrailingCRLF",
+		Input:  "\"foo\"\"bar\"\r\n",
+		Output: [][]string{{`foo"bar`}},
+	}, {
+		Name:   "EvenQuotes",
+		Input:  `""""""""`,
+		Output: [][]string{{`"""`}},
+	}, {
+		Name:  "OddQuotes",
+		Input: `"""""""`,
+		Error: &ParseError{StartLine: 1, Line: 1, Column: 7, Err: ErrQuote},
+	}, {
+		Name:       "LazyOddQuotes",
+		Input:      `"""""""`,
+		Output:     [][]string{{`"""`}},
+		LazyQuotes: true,
+	}, {
+		Name:  "BadComma1",
+		Comma: '\n',
+		Error: errInvalidDelim,
+	}, {
+		Name:  "BadComma2",
+		Comma: '\r',
+		Error: errInvalidDelim,
+	}, {
+		Name:  "BadComma3",
+		Comma: '"',
+		Error: errInvalidDelim,
+	}, {
+		Name:  "BadComma4",
+		Comma: utf8.RuneError,
+		Error: errInvalidDelim,
+	}, {
+		Name:    "BadComment1",
+		Comment: '\n',
+		Error:   errInvalidDelim,
+	}, {
+		Name:    "BadComment2",
+		Comment: '\r',
+		Error:   errInvalidDelim,
+	}, {
+		Name:    "BadComment3",
+		Comment: utf8.RuneError,
+		Error:   errInvalidDelim,
+	}, {
+		Name:    "BadCommaComment",
+		Comma:   'X',
+		Comment: 'X',
+		Error:   errInvalidDelim,
+	}}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			r := NewReader(strings.NewReader(tt.Input))
+
+			if tt.Comma != 0 {
+				r.Comma = tt.Comma
+			}
+			r.Comment = tt.Comment
+			if tt.UseFieldsPerRecord {
+				r.FieldsPerRecord = tt.FieldsPerRecord
+			} else {
+				r.FieldsPerRecord = -1
+			}
+			r.LazyQuotes = tt.LazyQuotes
+			r.TrimLeadingSpace = tt.TrimLeadingSpace
+			r.ReuseRecord = tt.ReuseRecord
+
+			out, err := r.ReadAll()
+			if !reflect.DeepEqual(err, tt.Error) {
+				t.Errorf("ReadAll() error:\ngot  %v\nwant %v", err, tt.Error)
+			} else if !reflect.DeepEqual(out, tt.Output) {
+				t.Errorf("ReadAll() output:\ngot  %q\nwant %q", out, tt.Output)
+			}
+		})
+	}
+}
+
+// nTimes is an io.Reader which yields the string s n times.
+type nTimes struct {
+	s   string
+	n   int
+	off int
+}
+
+func (r *nTimes) Read(p []byte) (n int, err error) {
+	for {
+		if r.n <= 0 || r.s == "" {
+			return n, io.EOF
+		}
+		n0 := copy(p, r.s[r.off:])
+		p = p[n0:]
+		n += n0
+		r.off += n0
+		if r.off == len(r.s) {
+			r.off = 0
+			r.n--
+		}
+		if len(p) == 0 {
+			return
+		}
+	}
+}
+
+// benchmarkRead measures reading the provided CSV rows data.
+// initReader, if non-nil, modifies the Reader before it's used.
+func benchmarkRead(b *testing.B, initReader func(*Reader), rows string) {
+	b.ReportAllocs()
+	r := NewReader(&nTimes{s: rows, n: b.N})
+	if initReader != nil {
+		initReader(r)
+	}
+	for {
+		_, err := r.Read()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}
+
+const benchmarkCSVData = `x,y,z,w
+x,y,z,
+x,y,,
+x,,,
+,,,
+"x","y","z","w"
+"x","y","z",""
+"x","y","",""
+"x","","",""
+"","","",""
+`
+
+func BenchmarkRead(b *testing.B) {
+	benchmarkRead(b, nil, benchmarkCSVData)
+}
+
+func BenchmarkReadWithFieldsPerRecord(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.FieldsPerRecord = 4 }, benchmarkCSVData)
+}
+
+func BenchmarkReadWithoutFieldsPerRecord(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.FieldsPerRecord = -1 }, benchmarkCSVData)
+}
+
+func BenchmarkReadLargeFields(b *testing.B) {
+	benchmarkRead(b, nil, strings.Repeat(`xxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+xxxxxxxxxxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvv
+,,zzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+`, 3))
+}
+
+func BenchmarkReadReuseRecord(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.ReuseRecord = true }, benchmarkCSVData)
+}
+
+func BenchmarkReadReuseRecordWithFieldsPerRecord(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.ReuseRecord = true; r.FieldsPerRecord = 4 }, benchmarkCSVData)
+}
+
+func BenchmarkReadReuseRecordWithoutFieldsPerRecord(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.ReuseRecord = true; r.FieldsPerRecord = -1 }, benchmarkCSVData)
+}
+
+func BenchmarkReadReuseRecordLargeFields(b *testing.B) {
+	benchmarkRead(b, func(r *Reader) { r.ReuseRecord = true }, strings.Repeat(`xxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+xxxxxxxxxxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvv
+,,zzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx,yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy,zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz,wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww,vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
+`, 3))
+}
diff --git a/src/encoding/csv/writer.go b/src/encoding/csv/writer.go
new file mode 100644
index 0000000..ac64b4d
--- /dev/null
+++ b/src/encoding/csv/writer.go
@@ -0,0 +1,181 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package csv
+
+import (
+	"bufio"
+	"io"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+)
+
+// A Writer writes records using CSV encoding.
+//
+// As returned by NewWriter, a Writer writes records terminated by a
+// newline and uses ',' as the field delimiter. The exported fields can be
+// changed to customize the details before the first call to Write or WriteAll.
+//
+// Comma is the field delimiter.
+//
+// If UseCRLF is true, the Writer ends each output line with \r\n instead of \n.
+//
+// The writes of individual records are buffered.
+// After all data has been written, the client should call the
+// Flush method to guarantee all data has been forwarded to
+// the underlying io.Writer.  Any errors that occurred should
+// be checked by calling the Error method.
+type Writer struct {
+	Comma   rune // Field delimiter (set to ',' by NewWriter)
+	UseCRLF bool // True to use \r\n as the line terminator
+	w       *bufio.Writer
+}
+
+// NewWriter returns a new Writer that writes to w.
+func NewWriter(w io.Writer) *Writer {
+	return &Writer{
+		Comma: ',',
+		w:     bufio.NewWriter(w),
+	}
+}
+
+// Write writes a single CSV record to w along with any necessary quoting.
+// A record is a slice of strings with each string being one field.
+// Writes are buffered, so Flush must eventually be called to ensure
+// that the record is written to the underlying io.Writer.
+func (w *Writer) Write(record []string) error {
+	if !validDelim(w.Comma) {
+		return errInvalidDelim
+	}
+
+	for n, field := range record {
+		if n > 0 {
+			if _, err := w.w.WriteRune(w.Comma); err != nil {
+				return err
+			}
+		}
+
+		// If we don't have to have a quoted field then just
+		// write out the field and continue to the next field.
+		if !w.fieldNeedsQuotes(field) {
+			if _, err := w.w.WriteString(field); err != nil {
+				return err
+			}
+			continue
+		}
+
+		if err := w.w.WriteByte('"'); err != nil {
+			return err
+		}
+		for len(field) > 0 {
+			// Search for special characters.
+			i := strings.IndexAny(field, "\"\r\n")
+			if i < 0 {
+				i = len(field)
+			}
+
+			// Copy verbatim everything before the special character.
+			if _, err := w.w.WriteString(field[:i]); err != nil {
+				return err
+			}
+			field = field[i:]
+
+			// Encode the special character.
+			if len(field) > 0 {
+				var err error
+				switch field[0] {
+				case '"':
+					_, err = w.w.WriteString(`""`)
+				case '\r':
+					if !w.UseCRLF {
+						err = w.w.WriteByte('\r')
+					}
+				case '\n':
+					if w.UseCRLF {
+						_, err = w.w.WriteString("\r\n")
+					} else {
+						err = w.w.WriteByte('\n')
+					}
+				}
+				field = field[1:]
+				if err != nil {
+					return err
+				}
+			}
+		}
+		if err := w.w.WriteByte('"'); err != nil {
+			return err
+		}
+	}
+	var err error
+	if w.UseCRLF {
+		_, err = w.w.WriteString("\r\n")
+	} else {
+		err = w.w.WriteByte('\n')
+	}
+	return err
+}
+
+// Flush writes any buffered data to the underlying io.Writer.
+// To check if an error occurred during the Flush, call Error.
+func (w *Writer) Flush() {
+	w.w.Flush()
+}
+
+// Error reports any error that has occurred during a previous Write or Flush.
+func (w *Writer) Error() error {
+	_, err := w.w.Write(nil)
+	return err
+}
+
+// WriteAll writes multiple CSV records to w using Write and then calls Flush,
+// returning any error from the Flush.
+func (w *Writer) WriteAll(records [][]string) error {
+	for _, record := range records {
+		err := w.Write(record)
+		if err != nil {
+			return err
+		}
+	}
+	return w.w.Flush()
+}
+
+// fieldNeedsQuotes reports whether our field must be enclosed in quotes.
+// Fields with a Comma, fields with a quote or newline, and
+// fields which start with a space must be enclosed in quotes.
+// We used to quote empty strings, but we do not anymore (as of Go 1.4).
+// The two representations should be equivalent, but Postgres distinguishes
+// quoted vs non-quoted empty string during database imports, and it has
+// an option to force the quoted behavior for non-quoted CSV but it has
+// no option to force the non-quoted behavior for quoted CSV, making
+// CSV with quoted empty strings strictly less useful.
+// Not quoting the empty string also makes this package match the behavior
+// of Microsoft Excel and Google Drive.
+// For Postgres, quote the data terminating string `\.`.
+func (w *Writer) fieldNeedsQuotes(field string) bool {
+	if field == "" {
+		return false
+	}
+
+	if field == `\.` {
+		return true
+	}
+
+	if w.Comma < utf8.RuneSelf {
+		for i := 0; i < len(field); i++ {
+			c := field[i]
+			if c == '\n' || c == '\r' || c == '"' || c == byte(w.Comma) {
+				return true
+			}
+		}
+	} else {
+		if strings.ContainsRune(field, w.Comma) || strings.ContainsAny(field, "\"\r\n") {
+			return true
+		}
+	}
+
+	r1, _ := utf8.DecodeRuneInString(field)
+	return unicode.IsSpace(r1)
+}
diff --git a/src/encoding/csv/writer_test.go b/src/encoding/csv/writer_test.go
new file mode 100644
index 0000000..ab28b0d
--- /dev/null
+++ b/src/encoding/csv/writer_test.go
@@ -0,0 +1,112 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package csv
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+)
+
+var writeTests = []struct {
+	Input   [][]string
+	Output  string
+	Error   error
+	UseCRLF bool
+	Comma   rune
+}{
+	{Input: [][]string{{"abc"}}, Output: "abc\n"},
+	{Input: [][]string{{"abc"}}, Output: "abc\r\n", UseCRLF: true},
+	{Input: [][]string{{`"abc"`}}, Output: `"""abc"""` + "\n"},
+	{Input: [][]string{{`a"b`}}, Output: `"a""b"` + "\n"},
+	{Input: [][]string{{`"a"b"`}}, Output: `"""a""b"""` + "\n"},
+	{Input: [][]string{{" abc"}}, Output: `" abc"` + "\n"},
+	{Input: [][]string{{"abc,def"}}, Output: `"abc,def"` + "\n"},
+	{Input: [][]string{{"abc", "def"}}, Output: "abc,def\n"},
+	{Input: [][]string{{"abc"}, {"def"}}, Output: "abc\ndef\n"},
+	{Input: [][]string{{"abc\ndef"}}, Output: "\"abc\ndef\"\n"},
+	{Input: [][]string{{"abc\ndef"}}, Output: "\"abc\r\ndef\"\r\n", UseCRLF: true},
+	{Input: [][]string{{"abc\rdef"}}, Output: "\"abcdef\"\r\n", UseCRLF: true},
+	{Input: [][]string{{"abc\rdef"}}, Output: "\"abc\rdef\"\n", UseCRLF: false},
+	{Input: [][]string{{""}}, Output: "\n"},
+	{Input: [][]string{{"", ""}}, Output: ",\n"},
+	{Input: [][]string{{"", "", ""}}, Output: ",,\n"},
+	{Input: [][]string{{"", "", "a"}}, Output: ",,a\n"},
+	{Input: [][]string{{"", "a", ""}}, Output: ",a,\n"},
+	{Input: [][]string{{"", "a", "a"}}, Output: ",a,a\n"},
+	{Input: [][]string{{"a", "", ""}}, Output: "a,,\n"},
+	{Input: [][]string{{"a", "", "a"}}, Output: "a,,a\n"},
+	{Input: [][]string{{"a", "a", ""}}, Output: "a,a,\n"},
+	{Input: [][]string{{"a", "a", "a"}}, Output: "a,a,a\n"},
+	{Input: [][]string{{`\.`}}, Output: "\"\\.\"\n"},
+	{Input: [][]string{{"x09\x41\xb4\x1c", "aktau"}}, Output: "x09\x41\xb4\x1c,aktau\n"},
+	{Input: [][]string{{",x09\x41\xb4\x1c", "aktau"}}, Output: "\",x09\x41\xb4\x1c\",aktau\n"},
+	{Input: [][]string{{"a", "a", ""}}, Output: "a|a|\n", Comma: '|'},
+	{Input: [][]string{{",", ",", ""}}, Output: ",|,|\n", Comma: '|'},
+	{Input: [][]string{{"foo"}}, Comma: '"', Error: errInvalidDelim},
+}
+
+func TestWrite(t *testing.T) {
+	for n, tt := range writeTests {
+		b := &bytes.Buffer{}
+		f := NewWriter(b)
+		f.UseCRLF = tt.UseCRLF
+		if tt.Comma != 0 {
+			f.Comma = tt.Comma
+		}
+		err := f.WriteAll(tt.Input)
+		if err != tt.Error {
+			t.Errorf("Unexpected error:\ngot  %v\nwant %v", err, tt.Error)
+		}
+		out := b.String()
+		if out != tt.Output {
+			t.Errorf("#%d: out=%q want %q", n, out, tt.Output)
+		}
+	}
+}
+
+type errorWriter struct{}
+
+func (e errorWriter) Write(b []byte) (int, error) {
+	return 0, errors.New("Test")
+}
+
+func TestError(t *testing.T) {
+	b := &bytes.Buffer{}
+	f := NewWriter(b)
+	f.Write([]string{"abc"})
+	f.Flush()
+	err := f.Error()
+
+	if err != nil {
+		t.Errorf("Unexpected error: %s\n", err)
+	}
+
+	f = NewWriter(errorWriter{})
+	f.Write([]string{"abc"})
+	f.Flush()
+	err = f.Error()
+
+	if err == nil {
+		t.Error("Error should not be nil")
+	}
+}
+
+var benchmarkWriteData = [][]string{
+	{"abc", "def", "12356", "1234567890987654311234432141542132"},
+	{"abc", "def", "12356", "1234567890987654311234432141542132"},
+	{"abc", "def", "12356", "1234567890987654311234432141542132"},
+}
+
+func BenchmarkWrite(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		w := NewWriter(&bytes.Buffer{})
+		err := w.WriteAll(benchmarkWriteData)
+		if err != nil {
+			b.Fatal(err)
+		}
+		w.Flush()
+	}
+}