Add implementation for TempFile with wild card prefix

Signed-off-by: Illya Chekrygin <illya.chekrygin@gmail.com>

go.mod

@@ -1,3 +1,8 @@
 module github.com/spf13/afero
 
-require golang.org/x/text v0.3.0
+require (
+	github.com/pkg/sftp v1.10.1
+	golang.org/x/text v0.3.0
+)
+
+go 1.13

go.sum

@@ -1,2 +1,20 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/kr/fs v0.1.0 h1:Jskdu9ieNAYnjxsi0LbQp1ulIKZV1LAFgK1tWhpZgl8=
+github.com/kr/fs v0.1.0/go.mod h1:FFnZGqtBN9Gxj7eW1uZ42v5BccTP0vu6NEaFoC2HwRg=
+github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
+github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/sftp v1.10.1 h1:VasscCm72135zRysgrJDKsntdmPN+OuU3+nnHYA9wyc=
+github.com/pkg/sftp v1.10.1/go.mod h1:lYOWFsE0bwd1+KfKJaKeuokY15vzFx25BLbzYYoAxZI=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20190820162420-60c769a6c586 h1:7KByu05hhLed2MO29w7p1XfZvZ13m8mub3shuVftRs0=
+golang.org/x/crypto v0.0.0-20190820162420-60c769a6c586/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=

ioutil.go

@@ -22,6 +22,7 @@ import (
 	"path/filepath"
 	"sort"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 )
@@ -147,7 +148,7 @@ func reseed() uint32 {
 	return uint32(time.Now().UnixNano() + int64(os.Getpid()))
 }
 
-func nextSuffix() string {
+func nextRandom() string {
 	randmu.Lock()
 	r := rand
 	if r == 0 {
@@ -159,27 +160,36 @@ func nextSuffix() string {
 	return strconv.Itoa(int(1e9 + r%1e9))[1:]
 }
 
-// TempFile creates a new temporary file in the directory dir
-// with a name beginning with prefix, opens the file for reading
-// and writing, and returns the resulting *File.
+// TempFile creates a new temporary file in the directory dir,
+// opens the file for reading and writing, and returns the resulting *os.File.
+// The filename is generated by taking pattern and adding a random
+// string to the end. If pattern includes a "*", the random string
+// replaces the last "*".
 // If dir is the empty string, TempFile uses the default directory
 // for temporary files (see os.TempDir).
 // Multiple programs calling TempFile simultaneously
-// will not choose the same file.  The caller can use f.Name()
-// to find the pathname of the file.  It is the caller's responsibility
+// will not choose the same file. The caller can use f.Name()
+// to find the pathname of the file. It is the caller's responsibility
 // to remove the file when no longer needed.
-func (a Afero) TempFile(dir, prefix string) (f File, err error) {
-	return TempFile(a.Fs, dir, prefix)
+func (a Afero) TempFile(dir, pattern string) (f File, err error) {
+	return TempFile(a.Fs, dir, pattern)
 }
 
-func TempFile(fs Fs, dir, prefix string) (f File, err error) {
+func TempFile(fs Fs, dir, pattern string) (f File, err error) {
 	if dir == "" {
 		dir = os.TempDir()
 	}
 
+	var prefix, suffix string
+	if pos := strings.LastIndex(pattern, "*"); pos != -1 {
+		prefix, suffix = pattern[:pos], pattern[pos+1:]
+	} else {
+		prefix = pattern
+	}
+
 	nconflict := 0
 	for i := 0; i < 10000; i++ {
-		name := filepath.Join(dir, prefix+nextSuffix())
+		name := filepath.Join(dir, prefix+nextRandom()+suffix)
 		f, err = fs.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_EXCL, 0600)
 		if os.IsExist(err) {
 			if nconflict++; nconflict > 10 {
@@ -211,7 +221,7 @@ func TempDir(fs Fs, dir, prefix string) (name string, err error) {
 
 	nconflict := 0
 	for i := 0; i < 10000; i++ {
-		try := filepath.Join(dir, prefix+nextSuffix())
+		try := filepath.Join(dir, prefix+nextRandom())
 		err = fs.Mkdir(try, 0700)
 		if os.IsExist(err) {
 			if nconflict++; nconflict > 10 {

ioutil_test.go

@@ -15,7 +15,11 @@
 
 package afero
 
-import "testing"
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+)
 
 func checkSizePath(t *testing.T, path string, size int64) {
 	dir, err := testFS.Stat(path)
@@ -110,3 +114,63 @@ func TestReadDir(t *testing.T) {
 		t.Fatalf("ReadDir %s: i-am-a-dir directory not found", dirname)
 	}
 }
+
+func TestTempFile(t *testing.T) {
+	type args struct {
+		dir     string
+		pattern string
+	}
+	tests := map[string]struct {
+		args args
+		want func(*testing.T, string)
+	}{
+		"foo": { // simple file name
+			args: args{
+				dir:     "",
+				pattern: "foo",
+			},
+			want: func(t *testing.T, base string) {
+				if !strings.HasPrefix(base, "foo") || len(base) <= len("foo") {
+					t.Errorf("TempFile() file = %s, invalid file name", base)
+				}
+			},
+		},
+		"foo.bar": { // file name w/ ext
+			args: args{
+				dir:     "",
+				pattern: "foo.bar",
+			},
+			want: func(t *testing.T, base string) {
+				if !strings.HasPrefix(base, "foo.bar") || len(base) <= len("foo.bar") {
+					t.Errorf("TempFile() file = %v, invalid file name", base)
+				}
+			},
+		},
+		"foo-*.bar": { // file name with wild card
+			args: args{
+				dir:     "",
+				pattern: "foo-*.bar",
+			},
+			want: func(t *testing.T, base string) {
+				if !(strings.HasPrefix(base, "foo-") || strings.HasPrefix(base, "bar")) ||
+					len(base) <= len("foo-*.bar") {
+					t.Errorf("TempFile() file = %v, invalid file name", base)
+				}
+			},
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			file, err := TempFile(NewMemMapFs(), tt.args.dir, tt.args.pattern)
+			if err != nil {
+				t.Errorf("TempFile() error = %v, none expected", err)
+				return
+			}
+			if file == nil {
+				t.Errorf("TempFile() file = %v, should not be nil", file)
+				return
+			}
+			tt.want(t, filepath.Base(file.Name()))
+		})
+	}
+}