main.go: remove file if on Flatten(..) failure

When a Flatten() fails, the main program used to leave an incomplete
file (usually zero-length). Now it will clean itself up on failure.
This commit is contained in:
Motiejus Jakštys 2021-08-25 08:49:30 +03:00
parent 6f40bc91be
commit 4568429a69
2 changed files with 60 additions and 16 deletions

16
main.go
View File

@ -53,15 +53,15 @@ type command struct {
Stdout io.Writer
}
func (c *command) execute(infile string, outfile string) (err error) {
func (c *command) execute(infile string, outfile string) (_err error) {
rd, err := os.Open(infile)
if err != nil {
return err
}
defer func() {
err1 := rd.Close()
if err == nil {
err = err1
err := rd.Close()
if _err == nil {
_err = err
}
}()
@ -74,9 +74,11 @@ func (c *command) execute(infile string, outfile string) (err error) {
return fmt.Errorf("create: %w", err)
}
defer func() {
err1 := outf.Close()
if err == nil {
err = err1
err := outf.Close()
if _err != nil {
os.Remove(outfile)
} else {
_err = err
}
}()
out = outf

View File

@ -2,8 +2,10 @@ package main
import (
"bytes"
"errors"
"io"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"testing"
@ -13,11 +15,13 @@ func TestExecute(t *testing.T) {
var _foo = []byte("foo foo")
tests := []struct {
name string
fixture func(*testing.T, string)
infile string
outfile string
wantErr string
name string
fixture func(*testing.T, string)
flattener func(io.ReadSeeker, io.Writer) error
infile string
outfile string
wantErr string
assertion func(*testing.T, string)
}{
{
name: "ok passthrough via stdout",
@ -41,6 +45,31 @@ func TestExecute(t *testing.T) {
},
outfile: "t20-out.txt",
},
{
name: "bad flattener should remove the file",
infile: "t30-in.txt",
fixture: func(t *testing.T, dir string) {
fname := filepath.Join(dir, "t30-in.txt")
if err := ioutil.WriteFile(fname, _foo, 0644); err != nil {
t.Fatalf("unexpected error: %v", err)
}
},
flattener: flattenBad,
outfile: "t30-out.txt",
wantErr: "some error",
assertion: func(t *testing.T, dir string) {
d, err := os.ReadDir(dir)
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
if len(d) != 1 {
t.Fatalf("expected 1 entry, got %d", len(d))
}
if d[0].Name() != "t30-in.txt" {
t.Fatalf("expected to find only t30-in.txt, got %s", d[0].Name())
}
},
},
{
name: "infile does not exist",
infile: "t3-does-not-exist.txt",
@ -57,7 +86,10 @@ func TestExecute(t *testing.T) {
t.Run(tt.name, func(t *testing.T) {
dir := t.TempDir()
var stdout bytes.Buffer
c := &command{Stdout: &stdout}
if tt.flattener == nil {
tt.flattener = flattenPassthrough
}
if tt.fixture != nil {
tt.fixture(t, dir)
}
@ -65,9 +97,14 @@ func TestExecute(t *testing.T) {
tt.outfile = filepath.Join(dir, tt.outfile)
}
inf := filepath.Join(dir, tt.infile)
c.flattener = flattenPassthrough
c := &command{Stdout: &stdout, flattener: tt.flattener}
err := c.execute(inf, tt.outfile)
if tt.assertion != nil {
tt.assertion(t, dir)
}
if tt.wantErr != "" {
if err == nil {
t.Fatal("expected error, got nil")
@ -78,10 +115,10 @@ func TestExecute(t *testing.T) {
}
return
}
var out []byte
if err != nil {
t.Fatalf("unexpected error: %v", err)
}
var out []byte
if tt.outfile == "-" {
out = stdout.Bytes()
} else {
@ -91,8 +128,9 @@ func TestExecute(t *testing.T) {
}
}
if !bytes.Equal([]byte("foo foo"), out) {
t.Errorf("out != foo foo: %s", string(out))
t.Errorf("out != foo foo: %q", string(out))
}
})
}
}
@ -101,3 +139,7 @@ func flattenPassthrough(r io.ReadSeeker, w io.Writer) error {
_, err := io.Copy(w, r)
return err
}
func flattenBad(_ io.ReadSeeker, _ io.Writer) error {
return errors.New("some error")
}