I'm trying to create a directory in Go with very specific permissions.
I need drwxrwxr-x but I don't know how to do it with os.Mkdir().
I've tried os.ModeDir, os.ModePerm and os.ModeSticky
I'm on linux and I do not care if the solution will work in windows. it can, but it doesn't have to.
My issue is that I'm trying to create a directory that is later used within the program itself (the program creates the directory and it uses it to write files to).
To quote https://stackoverflow.com/a/59963154/1079543:
all programs run with a umask setting...the set of permissions that the system will automatically remove from file and directory creation requests.
Setting the umask to 0 when you start the program produces the result you're looking for:
//go:build unix
package main
import (
"log"
"os"
"golang.org/x/sys/unix"
)
func main() {
unix.Umask(0)
if err := os.Mkdir("dirname", 0775); err != nil {
log.Fatalf("failed to create directory: %v", err)
}
}
//go:build unix should be true "if GOOS is a Unix or Unix-like system" per: https://pkg.go.dev/cmd/go#hdr-Build_constraints
The old way to do this was with syscall.Umask(0). This package is now deprecated per: https://go.googlesource.com/proposal/+/refs/heads/master/design/freeze-syscall.md
Related
Using Go - lang, according to the documentation, the os.Rename should be able to rename either a file or directory on any operating system.
On Linux it works as it should, pass either a file or directory into it and the file or directory are moved.
On windows i recieve an 'Access is denied' Error when trying to pass a folder.
It works 100% for files.
example:
source = c:\sourcefolder
destination = c:\destinationfolder
source contains:
C:\sourcefolder\file1.xml
C:\sourcefolder\file2.xml
C:\sourcefolder\foldername1
C:\sourcefolder\foldername1\file3.xml
C:\sourcefolder\foldername2
C:\sourcefolder\foldername2\file4.xml
both file1.xml and file2.xml will successfully copy to c:\destination.
But the folders and files within the folders crash out with access denied
The script is pretty simple:
source := "C:\\sourcefolder"
destination := "C:\\destinationfolder"
pathSeperator := "\\"
files, err := ioutil.ReadDir(source)
if err != nil {
fmt.Println("Move command execution error: ", err)
}
for _, f := range files {
fmt.Println(f.Name())
fmt.Println(f.Mode())
err := os.Rename(source+pathSeperator+f.Name(), destination+pathSeperator+f.Name())
if err != nil {
fmt.Println("Move command execution error: ", err)
panic(err)
}
}
Having searched stackoverflow and golang's resources, i found the issue listed in 2016 that reported this fault and according to the issue it was fixed, but i am unable to get this to work. Nowhere else that i can find lists this issue go golang.
checking the f.Mode for access, i get drwxrwxrwx and have complete access to all the files and directories.
Any help with this would be great, racking my mind. Thank you.
Quoted from comment. solved my issue.
Found the cause of the fault to be, if a windows explorer window is
open and has ANY visibility of the folders being moved (i.e. in the
tree on the left or right-pane) then access is denied as it can not
move the folders. If i minimize all the tree's so that the
source\destination folders are not visible and select a different sub
folder in windows explorer then the os.Rename works as it should,
moving all content from A to B really quick (as per linux)
I had the same issue with copying files within the same folder. The following solution works just fine (without closing or minimizing windows):
// read original file
origFile, _:= os.ReadFile(filePath)
// create new file with a different name
newFile, _ := os.Create(filePath + ".new")
// print data from original file to new file.
fmt.Fprintf(newFile, "%s", string(origFile))
I run the following code workingDir, _ := os.Getwd()
in server.go file which is under the root project and get the root path,
Now I need to move the server.go file to the following structure
myapp
src
server.go
and I want to ge the path of go/src/myapp
currently after I move the server.go under myapp->src>server.go I got path of go/src/myapp/src/server.go and I want to get the previews path ,
How should I do it in go automatically? or should I put ../ explicit in get path ?
os.Getwd() does not return your source file path. It returns program current working directory (Usually the directory that you executed your program).
Example:
Assume I have a main.go in /Users/Arman/go/src/github.com/rmaan/project/main.go that just outputs os.Getwd()
$ cd /Users/Arman/go/src/github.com/rmaan/project/
$ go run main.go
/Users/Arman/go/src/github.com/rmaan/project <nil>
If I change to other directory and execute there, result will change.
$ cd /Users/Arman/
$ go run ./go/src/github.com/rmaan/project/main.go
/Users/Arman <nil>
IMO you should explicitly pass the path you want to your program instead of trying to infer it from context (As it may change specially in production environment). Here is an example with flag package.
package main
import (
"fmt"
"flag"
)
func main() {
var myPath string
flag.StringVar(&myPath, "my-path", "/", "Provide project path as an absolute path")
flag.Parse()
fmt.Printf("provided path was %s\n", myPath)
}
then execute your program as follows:
$ cd /Users/Arman/go/src/github.com/rmaan/project/
$ go run main.go --my-path /Users/Arman/go/src/github.com/rmaan/project/
provided path was /Users/Arman/go/src/github.com/rmaan/project/
$ # or more easily
$ go run main.go --my-path `pwd`
provided path was /Users/Arman/go/src/github.com/rmaan/project/
If your project is a git repository you can also use the git rev-parse command with the --show-toplevel:
cmdOut, err := exec.Command("git", "rev-parse", "--show-toplevel").Output()
if err != nil {
assert.Fail(t, fmt.Sprintf(`Error on getting the go-kit base path: %s - %s`, err.Error(), string(cmdOut)))
return
}
fmt.Println(strings.TrimSpace(string(cmdOut)))
It'll print out the git project home path wherever in the sub path you are
I'm trying to read from a file in my project's directory.
My problem is, that depending on the caller, the path changes. The caller changes, because I want to unit test this code and the caller is not Main.go anymore.
This is what my project structure looks like:
The code where I try to access specialChars.txt from looks like this:
func RemoveSpecialChars(word string) string {
file, err := ioutil.ReadFile("wordlists/specialChars.txt")
[...]
}
This code works for the start from Main.go but not for the start from CleanupUtil_test.go. To get it working from the test I would need file, err := ioutil.ReadFile("../wordlists/specialChars.txt")
I found answers like this one: https://stackoverflow.com/a/32163888/2837489
_, filename, _, ok := runtime.Caller(0) which is obviously also dependent on the caller.
Is it possible to get the projects root path independent of the calling function?
Or is my code design wrong? Should I pass the file path into the function?
Starting from Go 1.16, you can use the embed package. This allows you to embed the files in the running go program. It comes with the caveat that the referenced directory needs to exist at or below the embedding file. In your case, the structure would look as follows:
-- main.go
-- cleanup
-- wordlist
\- specialChars.txt
CleanupUtil.go
CleanupUtil_test.go
You can reference the file using a go directive
// CleanupUtil.go
package cleanup
import (
"embed"
)
//go:embed wordlists/specialChars.txt
var content embed.FS
func RemoveSpecialChars(word string) string {
file, err := content.ReadFile("wordlists/specialChars.txt")
[...]
}
This program will run successfully regardless of where the program is executed. You should be able to reference this code in both your main.go file and your CleanupUtil_test.go file.
Pass in the filepath as a parameter to the function (as indicated in your last question).
More details:
The relative path "wordlists/specialChars.txt" is in fact not dependent on where the source file is located (such as Main.go or CleanupUtil_test.go), but where you execute it from. So you could run your tests from your root directory and then it would actually work. In short, the current working directory is relevant.
Still, I'd recommend specifying the path, because that makes your function more reusable and universal.
Maybe you don't even need to put this information into a file, but can simply have a string containing those chars. In this case you could also check if https://golang.org/pkg/regexp/#Regexp.ReplaceAll already covers your use case.
I have a project with next structure:
|_main.go
|_config
|_config.go
|_config_test.go
|_config.json
I'm having next code line in config.go:
file, _ := os.Open("config/config.json")
When I'm executing method contained this code line from main.go all is working. But when I'm trying to execute this method from config_test.go it produces error:
open config/config.json: no such file or directory
As I understood it is a working directory issue because I'm launching same code with relative path from different directories. How can I fix this problem without using full path in config.go?
Relative paths are always resolved basis your current directory. Hence it's better to avoid relative paths.
Use command line flags or a configuration management tool (better approach) like Viper
Also according to The Twelve-Factor App your config files should be outside your project.
Eg usage with Viper:
import "github.com/spf13/viper"
func init() {
viper.SetConfigName("config")
// Config files are stored here; multiple locations can be added
viper.AddConfigPath("$HOME/configs")
errViper := viper.ReadInConfig()
if errViper != nil {
panic(errViper)
}
// Get values from config.json
val := viper.GetString("some_key")
// Use the value
}
My current directory structure looks like the following:
App
- Template
- foo.go
- foo.tmpl
- Model
- bar.go
- Another
- Directory
- baz.go
The file foo.go uses ParseFiles to read in the template file during init.
import "text/template"
var qTemplate *template.Template
func init() {
qTemplate = template.Must(template.New("temp").ParseFiles("foo.tmpl"))
}
...
Unit tests for foo.go work as expected. However, I am now trying to run unit tests for bar.go and baz.go which both import foo.go and I get a panic on trying to open foo.tmpl.
/App/Model$ go test
panic: open foo.tmpl: no such file or directory
/App/Another/Directory$ go test
panic: open foo.tmpl: no such file or directory
I've tried specifying the template name as a relative directory ("./foo.tmpl"), a full directory ("~/go/src/github.com/App/Template/foo.tmpl"), an App relative directory ("/App/Template/foo.tmpl"), and others but nothing seems to work for both cases. The unit tests fail for either bar.go or baz.go (or both).
Where should my template file be placed and how should I call ParseFiles so that it can always find the template file regardless of which directory I call go test from?
Helpful tip:
Use os.Getwd() and filepath.Join() to find the absolute path of a relative file path.
Example
// File: showPath.go
package main
import (
"fmt"
"path/filepath"
"os"
)
func main(){
cwd, _ := os.Getwd()
fmt.Println( filepath.Join( cwd, "./template/index.gtpl" ) )
}
First off, I recommend that the template folder only contain templates for presentation and not go files.
Next, to make life easier, only run files from the root project directory. This will help make the path to an file consistent throughout go files nested within sub directories. Relative file paths start from where the current working directory, which is where the program was called from.
Example to show the change in current working directory
user#user:~/go/src/test$ go run showPath.go
/home/user/go/src/test/template/index.gtpl
user#user:~/go/src/test$ cd newFolder/
user#user:~/go/src/test/newFolder$ go run ../showPath.go
/home/user/go/src/test/newFolder/template/index.gtpl
As for test files, you can run individual test files by supplying the file name.
go test foo/foo_test.go
Lastly, use a base path and the path/filepath package to form file paths.
Example:
var (
basePath = "./public"
templatePath = filepath.Join(basePath, "template")
indexFile = filepath.Join(templatePath, "index.gtpl")
)