all: use new io.SeekFoo constants instead of os.SEEK_FOO

Automated change.

Fixes #15269

Change-Id: I8deb2ac0101d3f7c390467ceb0a1561b72edbb2f
Reviewed-on: https://go-review.googlesource.com/21962
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/archive/tar/reader.go b/src/archive/tar/reader.go
index c8cb69a..741fe01 100644
--- a/src/archive/tar/reader.go
+++ b/src/archive/tar/reader.go
@@ -13,7 +13,6 @@
 	"io"
 	"io/ioutil"
 	"math"
-	"os"
 	"strconv"
 	"strings"
 	"time"
@@ -523,10 +522,10 @@
 		// io.Seeker, but calling Seek always returns an error and performs
 		// no action. Thus, we try an innocent seek to the current position
 		// to see if Seek is really supported.
-		pos1, err := sr.Seek(0, os.SEEK_CUR)
+		pos1, err := sr.Seek(0, io.SeekCurrent)
 		if err == nil {
 			// Seek seems supported, so perform the real Seek.
-			pos2, err := sr.Seek(dataSkip-1, os.SEEK_CUR)
+			pos2, err := sr.Seek(dataSkip-1, io.SeekCurrent)
 			if err != nil {
 				tr.err = err
 				return tr.err
diff --git a/src/archive/zip/reader.go b/src/archive/zip/reader.go
index d741d10..f6c3ead 100644
--- a/src/archive/zip/reader.go
+++ b/src/archive/zip/reader.go
@@ -87,7 +87,7 @@
 	z.File = make([]*File, 0, end.directoryRecords)
 	z.Comment = end.comment
 	rs := io.NewSectionReader(r, 0, size)
-	if _, err = rs.Seek(int64(end.directoryOffset), os.SEEK_SET); err != nil {
+	if _, err = rs.Seek(int64(end.directoryOffset), io.SeekStart); err != nil {
 		return err
 	}
 	buf := bufio.NewReader(rs)
diff --git a/src/bytes/reader_test.go b/src/bytes/reader_test.go
index add985d..9341cd5 100644
--- a/src/bytes/reader_test.go
+++ b/src/bytes/reader_test.go
@@ -9,7 +9,6 @@
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"sync"
 	"testing"
 )
@@ -24,15 +23,15 @@
 		wantpos int64
 		seekerr string
 	}{
-		{seek: os.SEEK_SET, off: 0, n: 20, want: "0123456789"},
-		{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
-		{seek: os.SEEK_SET, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
-		{seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
-		{seek: os.SEEK_SET, n: 5, want: "01234"},
-		{seek: os.SEEK_CUR, n: 5, want: "56789"},
-		{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
+		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
+		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
+		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
+		{seek: io.SeekStart, off: -1, seekerr: "bytes.Reader.Seek: negative position"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33},
+		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1},
+		{seek: io.SeekStart, n: 5, want: "01234"},
+		{seek: io.SeekCurrent, n: 5, want: "56789"},
+		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
 	}
 
 	for i, tt := range tests {
@@ -63,7 +62,7 @@
 
 func TestReadAfterBigSeek(t *testing.T) {
 	r := NewReader([]byte("0123456789"))
-	if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
 		t.Fatal(err)
 	}
 	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {
diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index c28a964..8fbf23f 100644
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -269,7 +269,7 @@
 	switch f.Class {
 	case ELFCLASS32:
 		hdr := new(Header32)
-		sr.Seek(0, os.SEEK_SET)
+		sr.Seek(0, io.SeekStart)
 		if err := binary.Read(sr, f.ByteOrder, hdr); err != nil {
 			return nil, err
 		}
@@ -288,7 +288,7 @@
 		shstrndx = int(hdr.Shstrndx)
 	case ELFCLASS64:
 		hdr := new(Header64)
-		sr.Seek(0, os.SEEK_SET)
+		sr.Seek(0, io.SeekStart)
 		if err := binary.Read(sr, f.ByteOrder, hdr); err != nil {
 			return nil, err
 		}
@@ -315,7 +315,7 @@
 	f.Progs = make([]*Prog, phnum)
 	for i := 0; i < phnum; i++ {
 		off := phoff + int64(i)*int64(phentsize)
-		sr.Seek(off, os.SEEK_SET)
+		sr.Seek(off, io.SeekStart)
 		p := new(Prog)
 		switch f.Class {
 		case ELFCLASS32:
@@ -359,7 +359,7 @@
 	names := make([]uint32, shnum)
 	for i := 0; i < shnum; i++ {
 		off := shoff + int64(i)*int64(shentsize)
-		sr.Seek(off, os.SEEK_SET)
+		sr.Seek(off, io.SeekStart)
 		s := new(Section)
 		switch f.Class {
 		case ELFCLASS32:
diff --git a/src/debug/pe/file.go b/src/debug/pe/file.go
index 1acc368..c68ff1b 100644
--- a/src/debug/pe/file.go
+++ b/src/debug/pe/file.go
@@ -150,7 +150,7 @@
 	} else {
 		base = int64(0)
 	}
-	sr.Seek(base, os.SEEK_SET)
+	sr.Seek(base, io.SeekStart)
 	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
 		return nil, err
 	}
@@ -161,7 +161,7 @@
 	var ss []byte
 	if f.FileHeader.NumberOfSymbols > 0 {
 		// Get COFF string table, which is located at the end of the COFF symbol table.
-		sr.Seek(int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols), os.SEEK_SET)
+		sr.Seek(int64(f.FileHeader.PointerToSymbolTable+COFFSymbolSize*f.FileHeader.NumberOfSymbols), io.SeekStart)
 		var l uint32
 		if err := binary.Read(sr, binary.LittleEndian, &l); err != nil {
 			return nil, err
@@ -172,7 +172,7 @@
 		}
 
 		// Process COFF symbol table.
-		sr.Seek(int64(f.FileHeader.PointerToSymbolTable), os.SEEK_SET)
+		sr.Seek(int64(f.FileHeader.PointerToSymbolTable), io.SeekStart)
 		aux := uint8(0)
 		for i := 0; i < int(f.FileHeader.NumberOfSymbols); i++ {
 			cs := new(COFFSymbol)
@@ -203,7 +203,7 @@
 	}
 
 	// Read optional header.
-	sr.Seek(base, os.SEEK_SET)
+	sr.Seek(base, io.SeekStart)
 	if err := binary.Read(sr, binary.LittleEndian, &f.FileHeader); err != nil {
 		return nil, err
 	}
diff --git a/src/net/http/fs.go b/src/net/http/fs.go
index 5546d37..c7a58a6 100644
--- a/src/net/http/fs.go
+++ b/src/net/http/fs.go
@@ -121,11 +121,11 @@
 // Note that *os.File implements the io.ReadSeeker interface.
 func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker) {
 	sizeFunc := func() (int64, error) {
-		size, err := content.Seek(0, os.SEEK_END)
+		size, err := content.Seek(0, io.SeekEnd)
 		if err != nil {
 			return 0, errSeeker
 		}
-		_, err = content.Seek(0, os.SEEK_SET)
+		_, err = content.Seek(0, io.SeekStart)
 		if err != nil {
 			return 0, errSeeker
 		}
@@ -166,7 +166,7 @@
 			var buf [sniffLen]byte
 			n, _ := io.ReadFull(content, buf[:])
 			ctype = DetectContentType(buf[:n])
-			_, err := content.Seek(0, os.SEEK_SET) // rewind to output whole file
+			_, err := content.Seek(0, io.SeekStart) // rewind to output whole file
 			if err != nil {
 				Error(w, "seeker can't seek", StatusInternalServerError)
 				return
@@ -213,7 +213,7 @@
 			// A response to a request for a single range MUST NOT
 			// be sent using the multipart/byteranges media type."
 			ra := ranges[0]
-			if _, err := content.Seek(ra.start, os.SEEK_SET); err != nil {
+			if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
 				Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
 				return
 			}
@@ -236,7 +236,7 @@
 						pw.CloseWithError(err)
 						return
 					}
-					if _, err := content.Seek(ra.start, os.SEEK_SET); err != nil {
+					if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
 						pw.CloseWithError(err)
 						return
 					}
diff --git a/src/net/sendfile_dragonfly.go b/src/net/sendfile_dragonfly.go
index 17021c3..d4b825c 100644
--- a/src/net/sendfile_dragonfly.go
+++ b/src/net/sendfile_dragonfly.go
@@ -53,7 +53,7 @@
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
diff --git a/src/net/sendfile_freebsd.go b/src/net/sendfile_freebsd.go
index f7a8529..18cbb27 100644
--- a/src/net/sendfile_freebsd.go
+++ b/src/net/sendfile_freebsd.go
@@ -53,7 +53,7 @@
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
diff --git a/src/net/sendfile_solaris.go b/src/net/sendfile_solaris.go
index 20d2cdd..add70c3 100644
--- a/src/net/sendfile_solaris.go
+++ b/src/net/sendfile_solaris.go
@@ -57,7 +57,7 @@
 	// use the current position of the file -- if you pass it offset 0, it starts
 	// from offset 0. There's no way to tell it "start from current position", so
 	// we have to manage that explicitly.
-	pos, err := f.Seek(0, os.SEEK_CUR)
+	pos, err := f.Seek(0, io.SeekCurrent)
 	if err != nil {
 		return 0, err, false
 	}
diff --git a/src/os/exec/exec_test.go b/src/os/exec/exec_test.go
index 1f2fd12..ed2721b 100644
--- a/src/os/exec/exec_test.go
+++ b/src/os/exec/exec_test.go
@@ -479,7 +479,7 @@
 	if err != nil {
 		t.Fatalf("Write: %v", err)
 	}
-	_, err = tf.Seek(0, os.SEEK_SET)
+	_, err = tf.Seek(0, io.SeekStart)
 	if err != nil {
 		t.Fatalf("Seek: %v", err)
 	}
diff --git a/src/strings/reader_test.go b/src/strings/reader_test.go
index 7bca2e8..6e9d904 100644
--- a/src/strings/reader_test.go
+++ b/src/strings/reader_test.go
@@ -9,7 +9,6 @@
 	"fmt"
 	"io"
 	"io/ioutil"
-	"os"
 	"strings"
 	"sync"
 	"testing"
@@ -25,15 +24,15 @@
 		wantpos int64
 		seekerr string
 	}{
-		{seek: os.SEEK_SET, off: 0, n: 20, want: "0123456789"},
-		{seek: os.SEEK_SET, off: 1, n: 1, want: "1"},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 3, n: 2, want: "34"},
-		{seek: os.SEEK_SET, off: -1, seekerr: "strings.Reader.Seek: negative position"},
-		{seek: os.SEEK_SET, off: 1 << 33, wantpos: 1 << 33},
-		{seek: os.SEEK_CUR, off: 1, wantpos: 1<<33 + 1},
-		{seek: os.SEEK_SET, n: 5, want: "01234"},
-		{seek: os.SEEK_CUR, n: 5, want: "56789"},
-		{seek: os.SEEK_END, off: -1, n: 1, wantpos: 9, want: "9"},
+		{seek: io.SeekStart, off: 0, n: 20, want: "0123456789"},
+		{seek: io.SeekStart, off: 1, n: 1, want: "1"},
+		{seek: io.SeekCurrent, off: 1, wantpos: 3, n: 2, want: "34"},
+		{seek: io.SeekStart, off: -1, seekerr: "strings.Reader.Seek: negative position"},
+		{seek: io.SeekStart, off: 1 << 33, wantpos: 1 << 33},
+		{seek: io.SeekCurrent, off: 1, wantpos: 1<<33 + 1},
+		{seek: io.SeekStart, n: 5, want: "01234"},
+		{seek: io.SeekCurrent, n: 5, want: "56789"},
+		{seek: io.SeekEnd, off: -1, n: 1, wantpos: 9, want: "9"},
 	}
 
 	for i, tt := range tests {
@@ -64,7 +63,7 @@
 
 func TestReadAfterBigSeek(t *testing.T) {
 	r := strings.NewReader("0123456789")
-	if _, err := r.Seek(1<<31+5, os.SEEK_SET); err != nil {
+	if _, err := r.Seek(1<<31+5, io.SeekStart); err != nil {
 		t.Fatal(err)
 	}
 	if n, err := r.Read(make([]byte, 10)); n != 0 || err != io.EOF {