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Merge pull request #10693 from owncloud/thumbnails_fix_fs_race

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fix: use a tmp file and rename to prevent a possible race condition
This commit is contained in:
Juan Pablo Villafañez
2024-12-03 18:26:17 +01:00
committed by GitHub
parent 6a3eac3765 f3d91f8c69
commit b4f2faa1d6
2 changed files with 30 additions and 4 deletions
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8
changelog/unreleased/thumbnail-create-and-rename.md Normal file
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@@ -0,0 +1,8 @@
Bugfix: Fix possible race condition when a thumbnails is stored in the FS
A race condition could cause the thumbnail service to return a thumbnail
with 0 bytes or with partial content. In order to fix this, the service will
create a temporary file with the contents and then rename that file to its
final location.
https://github.com/owncloud/ocis/pull/10693

26
services/thumbnails/pkg/thumbnail/storage/filesystem.go
View File

@@ -62,14 +62,32 @@ func (s FileSystem) Put(key string, img []byte) error {
}
if _, err := os.Stat(imgPath); os.IsNotExist(err) {
f, err := os.Create(imgPath)
f, err := os.CreateTemp(dir, "tmpthumb")
if err != nil {
return errors.Wrapf(err, "could not create file \"%s\"", key)
return errors.Wrapf(err, "could not create temporary file for \"%s\"", key)
}
defer f.Close()
if _, err = f.Write(img); err != nil {
return errors.Wrapf(err, "could not write to file \"%s\"", key)
// if there was a problem writing, remove the temporary file
if _, writeErr := f.Write(img); writeErr != nil {
if remErr := os.Remove(f.Name()); remErr != nil {
return errors.Wrapf(remErr, "could not cleanup temporary file for \"%s\"", key)
}
return errors.Wrapf(writeErr, "could not write to temporary file for \"%s\"", key)
}
// if there wasn't a problem, ensure the data is written into disk
if synErr := f.Sync(); synErr != nil {
return errors.Wrapf(synErr, "could not sync temporary file data into the disk for \"%s\"", key)
}
// rename the temporary file to the final file
if renErr := os.Rename(f.Name(), imgPath); renErr != nil {
// if we couldn't rename, remove the temporary file
if remErr := os.Remove(f.Name()); remErr != nil {
return errors.Wrapf(remErr, "rename failed and could not cleanup temporary file for \"%s\"", key)
}
return errors.Wrapf(renErr, "could not rename temporary file to \"%s\"", key)
}
}