I followed the repo (https://github.com/360EntSecGroup-Skylar/excelize) tutorial to open a file:
f, err := excelize.OpenFile("./Book1.xlsx")
if err != nil {
fmt.Println(err)
return
}enter code here
But i couldn't find a tutorial about closing, something like:
defer f.Close()
Is there a way to do that?
You don't have to close it.
Just open it, and save it if you need to.
myFile, err := excelize.OpenFile("./Book1.xlsx")
if err != nil {
fmt.Println(err)
return
}
Then, do what you want.
Finally, just save it with the origin path :
err = myFile.Save()
if err != nil {
fmt.Println(err)
}
Or, an other path :
err := myFile.SaveAs("./myFolder/Book2.xlsx")
if err != nil {
fmt.Println(err)
}
Related
I need to zip/unzip folder that contains symlinks in a way that the structure will be saved and symlinks will be written as symlinks.
Is there a way doing this using Golang package "archive/zip"? or any other alternative way?
I tried to use this code, but 'io.Copy()' copies the target file content and we "lose" the symlink.
archive, err := os.Create("archive.zip")
if err != nil {
panic(err)
}
defer archive.Close()
zipWriter := zip.NewWriter(archive)
localPath := "../testdata/sym"
file, err := os.Open(localPath)
defer file.Close()
if err != nil {
panic(err)
}
w1 , err:= zipWriter.Create("w1")
if _, err = io.Copy(w1, file); err !=nil{
panic(err)
}
zipWriter.Close()
I used this PR : https://github.com/mholt/archiver/pull/92
and wrote symlink's target to writer.
I tested it on Linux and Windows.
archive, err := os.Create("archive.zip")
if err != nil {
panic(err)
}
defer archive.Close()
zipWriter := zip.NewWriter(archive)
defer zipWriter.Close()
localPath := "../testdata/sym"
symlinksTarget = "../a/b.in"
file, err := os.Open(localPath)
defer file.Close()
if err != nil {
panic(err)
}
info, err := os.Lstat(file.Name())
if err != nil {
panic(err)
}
header, err := zip.FileInfoHeader(info)
if err != nil {
panic(err)
}
header.Method = zip.Deflate
writer, err := zipWriter.CreateHeader(header)
if err != nil {
panic(err)
}
// Write symlink's target to writer - file's body for symlinks is the symlink target.
_, err = writer.Write([]byte(filepath.ToSlash(symlinksTarget)))
if err != nil {
panic(err)
}
I have the following function I'v tried to simplify to just adding a single file to a .zip archive.
Whatever I try, the resulting .zip file has no files listed in it. The size of the archive is correct. But when I try to extract all (windows), the archive is empty.
go version go1.10.1 windows/amd64
func Zip(src string, dst string) error {
destinationFile, err := os.Create(dst)
if err != nil {
return err
}
myZip := zip.NewWriter(destinationFile)
file := `C:\MA\testing\cldeploy-local.json`
zipFile, err := myZip.Create(file)
fsFile, err := os.Open(file)
if err != nil {
return err
}
_, err = io.Copy(zipFile, fsFile)
if err != nil {
return err
}
return nil
if err != nil {
return err
}
err = myZip.Close()
if err != nil {
return err
}
return nil
}
When I extract the file an error message appears: The compressed (zipped) Folder ... is invalid.
As answered by #JimB: file needs to be added as relative path
only forward slashes. can not start with slash
func Zip(src string, dst string) error {
destinationFile, err := os.Create(dst)
if err != nil {
return err
}
myZip := zip.NewWriter(destinationFile)
file := `C:\MA\testing\cldeploy-local.json`
// file needs to be added as relative path
// only forward slashes. can not start with slash
relPath := strings.TrimPrefix(file, filepath.Dir(src))
relPath = strings.Replace(relPath, `\`, `/`, -1)
relPath = strings.TrimLeft(relPath, `/`)
zipFile, err := myZip.Create(relPath)
fsFile, err := os.Open(file)
if err != nil {
return err
}
_, err = io.Copy(zipFile, fsFile)
if err != nil {
return err
}
return nil
if err != nil {
return err
}
err = myZip.Close()
if err != nil {
return err
}
return nil
}
I faced same issue.
Zipfile created, but empty if you open it with Windows Explorer. But if you open it with 7-zip filename looks like
Actual:
C:\Users\user\AppData\Local\Temp\products_list_432735630.zip\C:\Users\user\AppData\Local\Temp
Expected
C:\Users\user\AppData\Local\Temp\products_list_432735630.zip\
So if zip file and CSV file in one folder you must use relative path.
For Example
relativeFilename := filepath.Base(csvFile.Name())
zippedFile, err := zipper.Create(relativeFilename)
I wonder if possible to copy running .exe file to another folder. I am trying to do this using usual copy approach in Go like that.
func copy(src, dst string) error {
in, err := os.Open(src)
if err != nil {
return err
}
defer in.Close()
out, err := os.Create(dst)
if err != nil {
return err
}
defer out.Close()
_, err = io.Copy(out, in)
if err != nil {
return err
}
return out.Close()
}
...
copyErr := copy(os.Args[0], "D:"+"\\"+"whs.exe")
if copyErr != nil {
log.Panicf("copy -> %v", copyErr)
}
The file copied with the same size but I can't open it correctly. I have only a fast cmd flash. After several milliseconds, cmd is closing and I can't see even any errors.
I was trying to write errors to log file but it's empty.
f, err := os.OpenFile("debug.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0777)
if err != nil {
log.Panicf("setLogOutput -> %v", err)
}
defer f.Close()
log.SetOutput(f)
If I open not copied .exe file everything works correctly.
I've reduced my program to only one main method. The result was the same.
func main() {
log.Println("Starting...")
copyErr := copy(os.Args[0], "F:"+"\\"+"whs.exe")
if copyErr != nil {
log.Panicf("copy -> %v", copyErr)
}
os.Stdin.Read([]byte{0})
}
I have found an error.
The process cannot access the file because it is being used by another process.
I was trying to copy the .exe file to its own path.
func copy(src, dst string) error {
if _, err := os.Stat(dst); os.IsNotExist(err) {
in, err := os.Open(src)
if err != nil {
return err
}
defer in.Close()
out, err := os.Create(dst)
if err != nil {
return err
}
defer out.Close()
_, err = io.Copy(out, in)
if err != nil {
return err
}
}
return nil
}
I'm trying to download a remote file over ssh
The following approach works fine on shell
ssh hostname "tar cz /opt/local/folder" > folder.tar.gz
However the same approach on golang giving some difference in output artifact size. For example the same folders with pure shell produce artifact gz file 179B and same with go script 178B.
I assume that something has been missed from io.Reader or session got closed earlier. Kindly ask you guys to help.
Here is the example of my script:
func executeCmd(cmd, hostname string, config *ssh.ClientConfig, path string) error {
conn, _ := ssh.Dial("tcp", hostname+":22", config)
session, err := conn.NewSession()
if err != nil {
panic("Failed to create session: " + err.Error())
}
r, _ := session.StdoutPipe()
scanner := bufio.NewScanner(r)
go func() {
defer session.Close()
name := fmt.Sprintf("%s/backup_folder_%v.tar.gz", path, time.Now().Unix())
file, err := os.OpenFile(name, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
panic(err)
}
defer file.Close()
for scanner.Scan() {
fmt.Println(scanner.Bytes())
if err := scanner.Err(); err != nil {
fmt.Println(err)
}
if _, err = file.Write(scanner.Bytes()); err != nil {
log.Fatal(err)
}
}
}()
if err := session.Run(cmd); err != nil {
fmt.Println(err.Error())
panic("Failed to run: " + err.Error())
}
return nil
}
Thanks!
bufio.Scanner is for newline delimited text. According to the documentation, the scanner will remove the newline characters, stripping any 10s out of your binary file.
You don't need a goroutine to do the copy, because you can use session.Start to start the process asynchronously.
You probably don't need to use bufio either. You should be using io.Copy to copy the file, which has an internal buffer already on top of any buffering already done in the ssh client itself. If an additional buffer is needed for performance, wrap the session output in a bufio.Reader
Finally, you return an error value, so use it rather than panic'ing on regular error conditions.
conn, err := ssh.Dial("tcp", hostname+":22", config)
if err != nil {
return err
}
session, err := conn.NewSession()
if err != nil {
return err
}
defer session.Close()
r, err := session.StdoutPipe()
if err != nil {
return err
}
name := fmt.Sprintf("%s/backup_folder_%v.tar.gz", path, time.Now().Unix())
file, err := os.OpenFile(name, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
return err
}
defer file.Close()
if err := session.Start(cmd); err != nil {
return err
}
n, err := io.Copy(file, r)
if err != nil {
return err
}
if err := session.Wait(); err != nil {
return err
}
return nil
You can try doing something like this:
r, _ := session.StdoutPipe()
reader := bufio.NewReader(r)
go func() {
defer session.Close()
// open file etc
// 10 is the number of bytes you'd like to copy in one write operation
p := make([]byte, 10)
for {
n, err := reader.Read(p)
if err == io.EOF {
break
}
if err != nil {
log.Fatal("err", err)
}
if _, err = file.Write(p[:n]); err != nil {
log.Fatal(err)
}
}
}()
Make sure your goroutines are synchronized properly so output is completeky written to the file.
This code tries to tar some texts into a tar file and untar it.
The code for tar works but seems like I am doing something wrong
because untar the same file does not work.
When I untar the file that I manually tar.gz with OS GUI, it works but
not in this code.
http://play.golang.org/p/diTOojUuBX
func main() {
mpath := "a.tar.gz"
// defer os.Remove(mpath)
f, err := overwrite(mpath)
defer f.Close()
if err != nil {
panic(err)
}
gw := gzip.NewWriter(f)
defer gw.Close()
if err != nil {
panic(err)
}
tw := tar.NewWriter(gw)
for _, file := range files {
hdr := &tar.Header{
Name: file.Name,
Mode: 0600,
Size: int64(len(file.Body)),
}
if err := tw.WriteHeader(hdr); err != nil {
panic(err)
}
if _, err := tw.Write([]byte(file.Body)); err != nil {
panic(err)
}
}
// Make sure to check the error on Close.
if err := tw.Close(); err != nil {
panic(err)
}
fr, err := read(mpath)
defer fr.Close()
if err != nil {
panic(err)
}
gr, err := gzip.NewReader(fr)
defer gr.Close()
if err != nil {
panic(err)
}
tr := tar.NewReader(gr)
for {
hdr, err := tr.Next()
if err == io.EOF {
// end of tar archive
break
}
if err != nil {
panic(err)
}
path := hdr.Name
switch hdr.Typeflag {
case tar.TypeDir:
if err := os.MkdirAll(path, os.FileMode(hdr.Mode)); err != nil {
panic(err)
}
case tar.TypeReg:
ow, err := overwrite(path)
defer ow.Close()
if err != nil {
panic(err)
}
if _, err := io.Copy(ow, tr); err != nil {
panic(err)
}
default:
fmt.Printf("Can't: %c, %s\n", hdr.Typeflag, path)
}
}
}
It looks to me like there are two problems.
You are using defer to close your tar writer and gzip writer, however defers only execute when the current scope ends. Since you are running this all in one function your file handles will still be open when you attempt to read to untar and that may cause issues (perhaps file has not flushed fully for example).
You are not setting the Typeflag in the header when you create the tarball. While GNU tar may deal with this, assuming Typeflag '0', Go may not. According to the docs http://www.gnu.org/software/tar/manual/html_node/Standard.html the Typeflag for a regular file is byte '0'. This may mean you need to set the Typeflag on a per resource in your code (directories, files, links, etc).
I rewrote you code like the following, and it is working for me now. (note: storing everything as REGTYPE)
http://play.golang.org/p/3B7F_axr-i
EDIT
Ah-ha, I know the problem with #2 now. The Go library for tar uses FileInfoHeader in order to determine parts of the header, like Typeflag. Since your files are not really files on the system it cannot fill out the appropriate Typeflag.
GNU tar obviously knows how to deal with this, or perhaps tries its best to figure it out and is successful in this case.