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Improve comments and remove old redundant comments

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aneesh-n 2024-12-19 08:32:48 -07:00
parent 49f5db7534
commit 5a0f7bb4b2
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4 changed files with 31 additions and 29 deletions
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2
internal/fs/node_windows.go
View file

@ -340,8 +340,6 @@ func decryptFile(pathPointer *uint16) error {
// nodeFillGenericAttributes fills in the generic attributes for windows like File Attributes,
// Created time and Security Descriptors.
// It also checks if the volume supports extended attributes and stores the result in a map
// so that it does not have to be checked again for subsequent calls for paths in the same volume.
func nodeFillGenericAttributes(node *restic.Node, path string, stat *ExtendedFileInfo) (err error) {
isAds := restic.IsAds(path)
var attrs restic.WindowsAttributes

7
internal/restic/node.go
View file

@ -46,11 +46,10 @@ const (
TypeFileAttributes GenericAttributeType = "windows.file_attributes"
// TypeSecurityDescriptor is the GenericAttributeType used for storing security descriptors including owner, group, discretionary access control list (DACL), system access control list (SACL)) for windows files within the generic attributes map.
TypeSecurityDescriptor GenericAttributeType = "windows.security_descriptor"
// TypeHasADS is the GenericAttributeType used for to indicate that a file has Alternate Data Streams attached to it.
// The value will have a | separate list of the ADS attached to the file. Those files will have a generic attribute TypeIsADS.
// TypeHasADS is the GenericAttributeType used to indicate that a file has Alternate Data Streams attached to it.
// The value will have a array of the ADS attached to the file. Those files will have a generic attribute TypeIsADS.
TypeHasADS GenericAttributeType = "windows.has_ads"
// TypeIsADS is the GenericAttributeType used for to indicate that a file represents an Alternate Data Streams and is attached to (child of) a file in the value.
// The file in the value will be a file which has a generic attribute TypeHasADS.
// TypeIsADS is the GenericAttributeType with a boolean value used to indicate that the file represents an Alternate Data Stream.
TypeIsADS GenericAttributeType = "windows.is_ads"
// Generic Attributes for other OS types should be defined here.

8
internal/restic/node_windows.go
View file

@ -10,8 +10,6 @@ import (
"github.com/restic/restic/internal/debug"
)
const AdsSeparator = "|"
// WindowsAttributes are the genericAttributes for Windows OS
type WindowsAttributes struct {
// CreationTime is used for storing creation time for windows files.
@ -21,10 +19,10 @@ type WindowsAttributes struct {
// SecurityDescriptor is used for storing security descriptors which includes
// owner, group, discretionary access control list (DACL), system access control list (SACL)
SecurityDescriptor *[]byte `generic:"security_descriptor"`
// HasADS is used for storing if a file has an Alternate Data Stream attached to it.
// HasADS is used to indicate that a file has Alternate Data Streams attached to it.
// The value will have a array of the ADS attached to the file. Those files will have a generic attribute TypeIsADS.
HasADS *[]string `generic:"has_ads"`
// IsADS is used for storing if a file is an Alternate Data Stream and is attached to (child of) a file in the value.
// The file in the value will be a file which has a generic attribute TypeHasADS.
// IsADS is used to indicate that the file represents an Alternate Data Stream.
IsADS *bool `generic:"is_ads"`
}

43
internal/restorer/fileswriter_windows.go
View file

@ -12,17 +12,27 @@ import (
)
// createOrOpenFile opens the file and handles the readonly attribute and ads related logic during file creation.
// Readonly files - if an existing file is detected as readonly we clear the flag because otherwise we cannot
//
// Readonly files -
// If an existing file is detected as readonly we clear the flag because otherwise we cannot
// make changes to the file. The readonly attribute would be set again in the second pass when the attributes
// are set if the file version being restored has the readonly bit.
// ADS files need special handling - Each stream is treated as a separate file in restic. This method is called
// for the main file which has the streams and for each stream.
// If the ads stream calls this method first and the main file doesn't already exist, then creating the file
//
// ADS files need special handling -
// Each stream is treated as a separate file in restic. This function is called for the main file which has the
// streams and for each stream.
// If the ads stream calls this function first and the main file doesn't already exist, then creating the file
// for the streams causes the main file to automatically get created with 0 size. Hence we need to be careful
// while creating the main file. If we blindly create it with the os.O_CREATE option, it could overwrite the
// stream. However creating the stream with os.O_CREATE option does not overwrite the mainfile if it already
// exists. It will simply attach the new stream to the main file if the main file existed, otherwise it will
// while creating the main file after that. If we blindly create the main file with the os.O_CREATE option,
// it could overwrite the file already created when the stream was created. However creating the stream with
// os.O_CREATE option does not overwrite the mainfile if it already exists.
// It will simply attach the new stream to the main file if the main file existed, otherwise it will
// create the 0 size main file.
// So we need to sync on the main file path if the file either has ads or is an ads file and then while creating
// the main file, we need to check if the file already exists and if it does, we should not overwrite it
// but instead we should simply return the file that we already created.
//
// Reduction in number of streams when restoring an old mainfile version -
// Another case to handle is if the mainfile already had more streams and the file version being restored has
// less streams, then the extra streams need to be removed from the main file. The stream names are present
// as the value in the generic attribute TypeHasAds.
@ -91,7 +101,7 @@ func openFileImpl(path string, createSize int64, fileInfo *fileInfo) (mainPath s
// If the error was because access is denied,
// the calling method will try to check if the file is readonly and if so, it tries to
// remove the readonly attribute and call this openFileImpl method again once.
// If this method throws access denied again, then it stops trying and return the error.
// If this method throws access denied again, then it stops trying and returns the error.
return mainPath, nil, err
}
//At this point readonly flag is already handled and we need not consider it anymore.
@ -121,8 +131,7 @@ func handleCreateFile(path string, fileIn *os.File, isAdsRelated, hasAds, isAds,
func handleCreateFileNonAds(path string, fileIn *os.File, isAlreadyExists bool) (file *os.File, err error) {
// This is the simple case.
if isAlreadyExists {
// If the non-ads file already exists, return the file
// that we already created without create option.
// If the non-ads file already exists, return the file that we already created without create option.
return fileIn, nil
} else {
// If the non-ads file did not exist, try creating the file with create flag.
@ -132,15 +141,13 @@ func handleCreateFileNonAds(path string, fileIn *os.File, isAlreadyExists bool)
// handleCreateFileAds handles all the various combination of states while creating the ads related file if needed.
func handleCreateFileAds(path string, fileIn *os.File, hasAds, isAds, isAlreadyExists bool) (file *os.File, err error) {
// This is the simple case. We do not need to change the encryption attribute.
if isAlreadyExists {
// If the ads related file already exists and no change to encryption, return the file
// that we already created without create option.
// If the ads related file already exists, return the file that we already created without create option.
return fileIn, nil
} else {
// If the ads related file did not exist, first check if it is a hasAds or isAds
// If the ads related file did not exist, first check if it is an ads file or a file which has ads files attached.
if isAds {
// If it is an ads file, then we can simple open it with create options without worrying about overwriting.
// If it is an ads file, then we can simply open it with create options without worrying about overwriting.
return fs.OpenFile(path, fs.O_CREATE|fs.O_WRONLY|fs.O_NOFOLLOW, 0600)
}
if hasAds {
@ -151,18 +158,18 @@ func handleCreateFileAds(path string, fileIn *os.File, hasAds, isAds, isAlreadyE
if os.IsNotExist(err) {
// We confirmed that the main file still doesn't exist after syncing.
// Hence creating the file with the create flag.
// Directly open the main file with create option as it should not be encrypted.
return fs.OpenFile(path, fs.O_CREATE|fs.O_WRONLY|fs.O_NOFOLLOW, 0600)
} else {
// Some other error occured so stop processing and return it.
return nil, err
}
} else {
// This means that the main file exists now and requires no change to encryption. Simply return it.
// This means that the main file exists now and we should simply return it,
// it does not have the create flag.
return file, err
}
}
return nil, errors.New("invalid case for ads same file encryption")
return nil, errors.New("invalid case for ads")
}
}