buildah/pkg/util/util.go

82 lines
2.3 KiB
Go

package util
import (
"io/ioutil"
"os"
"path/filepath"
"strings"
"github.com/pkg/errors"
)
// Mirrors path to a tmpfile if path points to a
// file descriptor instead of actual file on filesystem
// reason: operations with file descriptors are can lead
// to edge cases where content on FD is not in a consumable
// state after first consumption.
// returns path as string and bool to confirm if temp file
// was created and needs to be cleaned up.
func MirrorToTempFileIfPathIsDescriptor(file string) (string, bool) {
// one use-case is discussed here
// https://github.com/containers/buildah/issues/3070
if !strings.HasPrefix(file, "/dev/fd") {
return file, false
}
b, err := ioutil.ReadFile(file)
if err != nil {
// if anything goes wrong return original path
return file, false
}
tmpfile, err := ioutil.TempFile(os.TempDir(), "buildah-temp-file")
if err != nil {
return file, false
}
if _, err := tmpfile.Write(b); err != nil {
// if anything goes wrong return original path
return file, false
}
return tmpfile.Name(), true
}
// DiscoverContainerfile tries to find a Containerfile or a Dockerfile within the provided `path`.
func DiscoverContainerfile(path string) (foundCtrFile string, err error) {
// Test for existence of the file
target, err := os.Stat(path)
if err != nil {
return "", errors.Wrap(err, "discovering Containerfile")
}
switch mode := target.Mode(); {
case mode.IsDir():
// If the path is a real directory, we assume a Containerfile or a Dockerfile within it
ctrfile := filepath.Join(path, "Containerfile")
// Test for existence of the Containerfile file
file, err := os.Stat(ctrfile)
if err != nil {
// See if we have a Dockerfile within it
ctrfile = filepath.Join(path, "Dockerfile")
// Test for existence of the Dockerfile file
file, err = os.Stat(ctrfile)
if err != nil {
return "", errors.Wrap(err, "cannot find Containerfile or Dockerfile in context directory")
}
}
// The file exists, now verify the correct mode
if mode := file.Mode(); mode.IsRegular() {
foundCtrFile = ctrfile
} else {
return "", errors.Errorf("assumed Containerfile %q is not a file", ctrfile)
}
case mode.IsRegular():
// If the context dir is a file, we assume this as Containerfile
foundCtrFile = path
}
return foundCtrFile, nil
}