// Asynchronously tries to read the contents of the PAX metadata entry as extended attributes, tries to also read the actual entry that follows,
// and returns the actual entry with the processed extended attributes saved in the _extendedAttributes dictionary.
private async ValueTask <TarHeader?> TryProcessExtendedAttributesHeaderAsync(TarHeader extendedAttributesHeader, bool copyData, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
// Now get the actual entry
TarHeader?actualHeader = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Pax, cancellationToken).ConfigureAwait(false);
if (actualHeader == null)
{
return(null);
}
// We're currently processing an extended attributes header, so we can never have two extended entries in a row
if (actualHeader._typeFlag is TarEntryType.GlobalExtendedAttributes or
TarEntryType.ExtendedAttributes or
TarEntryType.LongLink or
TarEntryType.LongPath)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, actualHeader._typeFlag, TarEntryType.ExtendedAttributes));
}
// Can't have two extended attribute metadata entries in a row
if (actualHeader._typeFlag is TarEntryType.ExtendedAttributes)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, TarEntryType.ExtendedAttributes, TarEntryType.ExtendedAttributes));
}
// Replace all the attributes representing standard fields with the extended ones, if any
actualHeader.ReplaceNormalAttributesWithExtended(extendedAttributesHeader.ExtendedAttributes);
return(actualHeader);
}
// Asynchronously attempts to read the next tar archive entry header.
// Returns true if an entry header was collected successfully, false otherwise.
// An entry header represents any typeflag that is contains metadata.
// Metadata typeflags: ExtendedAttributes, GlobalExtendedAttributes, LongLink, LongPath.
// Metadata typeflag entries get handled internally by this method until a valid header entry can be returned.
private async ValueTask <(bool, TarHeader)> TryGetNextEntryHeaderAsync(bool copyData, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
Debug.Assert(!_reachedEndMarkers);
(bool result, TarHeader header) = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Unknown, cancellationToken).ConfigureAwait(false);
if (!result)
{
return(false, default);
// Asynchronously attempts to read the next tar archive entry header.
// Returns true if an entry header was collected successfully, false otherwise.
// An entry header represents any typeflag that is contains metadata.
// Metadata typeflags: ExtendedAttributes, GlobalExtendedAttributes, LongLink, LongPath.
// Metadata typeflag entries get handled internally by this method until a valid header entry can be returned.
private async ValueTask <TarHeader?> TryGetNextEntryHeaderAsync(bool copyData, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
Debug.Assert(!_reachedEndMarkers);
TarHeader?header = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Unknown, cancellationToken).ConfigureAwait(false);
if (header == null)
{
return(null);
}
// If a metadata typeflag entry is retrieved, handle it here, then read the next entry
// PAX metadata
if (header._typeFlag is TarEntryType.ExtendedAttributes)
{
TarHeader?mainHeader = await TryProcessExtendedAttributesHeaderAsync(header, copyData, cancellationToken).ConfigureAwait(false);
if (mainHeader == null)
{
return(null);
}
header = mainHeader;
}
// GNU metadata
else if (header._typeFlag is TarEntryType.LongLink or TarEntryType.LongPath)
{
TarHeader?mainHeader = await TryProcessGnuMetadataHeaderAsync(header, copyData, cancellationToken).ConfigureAwait(false);
if (mainHeader == null)
{
return(null);
}
header = mainHeader;
}
return(header);
}
// Asynchronously tries to read the contents of the PAX metadata entry as extended attributes, tries to also read the actual entry that follows,
// and returns the actual entry with the processed extended attributes saved in the _extendedAttributes dictionary.
private async ValueTask <TarHeader?> TryProcessExtendedAttributesHeaderAsync(TarHeader extendedAttributesHeader, bool copyData, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
// Don't process the data block of the actual entry just yet, because there's a slim chance
// that the extended attributes contain a size that we need to override in the header
TarHeader?actualHeader = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Pax, processDataBlock : false, cancellationToken).ConfigureAwait(false);
if (actualHeader == null)
{
return(null);
}
// We're currently processing an extended attributes header, so we can never have two extended entries in a row
if (actualHeader._typeFlag is TarEntryType.GlobalExtendedAttributes or
TarEntryType.ExtendedAttributes or
TarEntryType.LongLink or
TarEntryType.LongPath)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, actualHeader._typeFlag, TarEntryType.ExtendedAttributes));
}
// Can't have two extended attribute metadata entries in a row
if (actualHeader._typeFlag is TarEntryType.ExtendedAttributes)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, TarEntryType.ExtendedAttributes, TarEntryType.ExtendedAttributes));
}
// Replace all the attributes representing standard fields with the extended ones, if any
actualHeader.ReplaceNormalAttributesWithExtended(extendedAttributesHeader.ExtendedAttributes);
// We retrieved the extended attributes, now we can read the data, and always with the right size
actualHeader.ProcessDataBlock(_archiveStream, copyData);
return(actualHeader);
}
// Asynchronously tries to read the contents of the GNU metadata entry, then tries to read the next entry, which could either be another GNU metadata entry
// or the actual entry. Processes them all and returns the actual entry updating its path and/or linkpath fields as needed.
private async ValueTask <TarHeader?> TryProcessGnuMetadataHeaderAsync(TarHeader header, bool copyData, CancellationToken cancellationToken)
{
cancellationToken.ThrowIfCancellationRequested();
// Get the second entry, which is the actual entry
TarHeader?secondHeader = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Gnu, cancellationToken).ConfigureAwait(false);
if (secondHeader == null)
{
return(null);
}
// Can't have two identical metadata entries in a row
if (secondHeader._typeFlag == header._typeFlag)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, secondHeader._typeFlag, header._typeFlag));
}
TarHeader finalHeader;
// It's possible to have the two different metadata entries in a row
if ((header._typeFlag is TarEntryType.LongLink && secondHeader._typeFlag is TarEntryType.LongPath) ||
(header._typeFlag is TarEntryType.LongPath && secondHeader._typeFlag is TarEntryType.LongLink))
{
// Get the third entry, which is the actual entry
TarHeader?thirdHeader = await TarHeader.TryGetNextHeaderAsync(_archiveStream, copyData, TarEntryFormat.Gnu, cancellationToken).ConfigureAwait(false);
if (thirdHeader == null)
{
return(null);
}
// Can't have three GNU metadata entries in a row
if (thirdHeader._typeFlag is TarEntryType.LongLink or TarEntryType.LongPath)
{
throw new FormatException(string.Format(SR.TarUnexpectedMetadataEntry, thirdHeader._typeFlag, secondHeader._typeFlag));
}
if (header._typeFlag is TarEntryType.LongLink)
{
Debug.Assert(header._linkName != null);
Debug.Assert(secondHeader._name != null);
thirdHeader._linkName = header._linkName;
thirdHeader._name = secondHeader._name;
}
else if (header._typeFlag is TarEntryType.LongPath)
{
Debug.Assert(header._name != null);
Debug.Assert(secondHeader._linkName != null);
thirdHeader._name = header._name;
thirdHeader._linkName = secondHeader._linkName;
}
finalHeader = thirdHeader;
}
// Only one metadata entry was found
else
{
if (header._typeFlag is TarEntryType.LongLink)
{
Debug.Assert(header._linkName != null);
secondHeader._linkName = header._linkName;
}
else if (header._typeFlag is TarEntryType.LongPath)
{
Debug.Assert(header._name != null);
secondHeader._name = header._name;
}
finalHeader = secondHeader;
}
return(finalHeader);
}