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AnderG
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Jul 19, 2024
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,110 @@ | ||
| package main | ||
|
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||
| import ( | ||
| "encoding/json" | ||
| "errors" | ||
| "fmt" | ||
| "io" | ||
| "os" | ||
|
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| "github.com/docker/go-plugins-helpers/volume" | ||
| ) | ||
|
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| type ActiveMount struct { | ||
| UsageCount int | ||
| } | ||
|
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| func (d *DockerOnTop) Activate(request *volume.MountRequest, activemountsdir lockedFile) (bool, error) { | ||
| var activeMount ActiveMount | ||
| var result bool | ||
|
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| _, readDirErr := activemountsdir.ReadDir(1) // Check if there are any files inside activemounts dir | ||
| if readDirErr == nil { | ||
| // There is something no need to mount the filesystem again | ||
| result = false | ||
| } else if errors.Is(readDirErr, io.EOF) { | ||
| // The directory is empty, mount the filesystem | ||
| result = true | ||
| } else { | ||
| log.Errorf("Failed to list the activemounts directory: %v", readDirErr) | ||
| return false, fmt.Errorf("failed to list activemounts/ %v", readDirErr) | ||
| } | ||
|
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| activemountFilePath := d.activemountsdir(request.Name) + request.ID | ||
| file, err := os.Open(activemountFilePath) | ||
|
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| if err == nil { | ||
| // The file can exist from a previous mount when doing a docker cp on an already mounted container, no need to mount the filesystem again | ||
| payload, _ := io.ReadAll(file) | ||
| json.Unmarshal(payload, &activeMount) | ||
| file.Close() | ||
| } else if os.IsNotExist(err) { | ||
| // Default case, we need to create a new active mount, the filesystem needs to be mounted | ||
| activeMount = ActiveMount{UsageCount: 0} | ||
| } else { | ||
| log.Errorf("Active mount file %s exists but cannot be read.", activemountFilePath) | ||
| return false, fmt.Errorf("active mount file %s exists but cannot be read", activemountFilePath) | ||
| } | ||
|
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| activeMount.UsageCount++ | ||
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| payload, _ := json.Marshal(activeMount) | ||
| err = os.WriteFile(activemountFilePath, payload, 0o666) | ||
| if err != nil { | ||
| log.Errorf("Active mount file %s cannot be written.", activemountFilePath) | ||
| return false, fmt.Errorf("active mount file %s cannot be written", activemountFilePath) | ||
| } | ||
|
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| return result, nil | ||
| } | ||
|
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| func (d *DockerOnTop) Deactivate(request *volume.UnmountRequest, activemountsdir lockedFile) (bool, error) { | ||
|
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| dirEntries, readDirErr := activemountsdir.ReadDir(2) // Check if there is any _other_ container using the volume | ||
| if errors.Is(readDirErr, io.EOF) { | ||
| // If directory is empty, unmount overlay and clean up | ||
| log.Errorf("There are no active mount files and one was expected. Unmounting.") | ||
| return true, fmt.Errorf("there are no active mount files and one was expected. Unmounting") | ||
| } else if readDirErr != nil { | ||
| log.Errorf("Failed to list the activemounts directory: %v", readDirErr) | ||
| return false, fmt.Errorf("failed to list activemounts/ %v", readDirErr) | ||
| } | ||
|
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| var activeMount ActiveMount | ||
| activemountFilePath := d.activemountsdir(request.Name) + request.ID | ||
|
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| otherVolumesPresent := len(dirEntries) > 1 || dirEntries[0].Name() != request.ID | ||
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| file, err := os.Open(activemountFilePath) | ||
|
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| if err == nil { | ||
| payload, _ := io.ReadAll(file) | ||
| json.Unmarshal(payload, &activeMount) | ||
| file.Close() | ||
| } else if os.IsNotExist(err) { | ||
| log.Errorf("The active mount file %s was expected but is not there", activemountFilePath) | ||
| return !otherVolumesPresent, fmt.Errorf("the active mount file %s was expected but is not there", activemountFilePath) | ||
| } else { | ||
| log.Errorf("The active mount file %s could not be opened", activemountFilePath) | ||
| return false, fmt.Errorf("the active mount file %s could not be opened", activemountFilePath) | ||
| } | ||
|
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| activeMount.UsageCount-- | ||
|
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| if activeMount.UsageCount == 0 { | ||
| err := os.Remove(activemountFilePath) | ||
| if err != nil { | ||
| log.Errorf("The active mount file %s could not be deleted", activemountFilePath) | ||
| return false, fmt.Errorf("the active mount file %s could not be deleted", activemountFilePath) | ||
| } | ||
| return !otherVolumesPresent, nil | ||
| } else { | ||
| payload, _ := json.Marshal(activeMount) | ||
| err = os.WriteFile(activemountFilePath, payload, 0o666) | ||
| if err != nil { | ||
| log.Errorf("The active mount file %s could not be updated", activemountFilePath) | ||
| return false, fmt.Errorf("the active mount file %s could not be updated", activemountFilePath) | ||
| } | ||
| return false, nil | ||
| } | ||
| } |
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