Read directory entries

andybalholm

Apr 6, 2023, 12:52 AM

DF5RFSLHH4Y6GBM7MUTRTHXK5WC7FWV6RSEKDYGTKPSAKE2PQBXQC

Dependencies

[2] 7VEHGTEY Switch from reading text format to reading binary format.
[3] AYLFNM5C Add the ability to output the contents of a file.
[*] EKAB33DH Start using some parser combinators

Change contents

edit in output.go at line 4

[3.59]

[3.59]

"errors"
edit in output.go at line 140

[3.3030]

type DirEntry struct {
IsDirectory bool
Name string
Encoding string
Inode *Block
}

func dirEntry(data []byte) ([]byte, DirEntry, error) {
var d DirEntry
var err error
data, d.IsDirectory, err = mapValue(uint16LE, func(n uint16) bool {
return n&0x200 != 0
})(data)
if err != err {
return data, d, err
}

_, _, err = tuple(
assign(&d.Name, toString(lengthData(uint64LE))),
assign(&d.Encoding, mapValue(option(toString(lengthData(uint64LE))), func(p *string) string {
if p == nil {
return ""
}
return *p
})),
)(data)
if err != nil {
d.Name = string(data)
}
return nil, d, nil
}

func ReadDir(dirInode *Block) ([]DirEntry, error) {
var entries []DirEntry
for _, e := range dirInode.Edges {
if e.Flag&EdgeFlagsDeleted != 0 {
continue
}
if e.Flag&EdgeFlagsFolder == 0 {
return nil, errors.New("ReadDir: found an edge that doesn't have Folder flag set")
}
b := e.To
_, entry, err := dirEntry(b.Content)
if err != nil {
return nil, fmt.Errorf("not a valid directory entry: %q", b.Content)
}
for _, inodeEdge := range b.Edges {
if inodeEdge.Flag&EdgeFlagsDeleted != 0 {
continue
}
if inodeEdge.Flag&EdgeFlagsFolder == 0 {
return nil, fmt.Errorf("directory entry for %s has an edge without Folder flag", entry.Name)
}
entry.Inode = inodeEdge.To
break
}
if entry.Inode == nil {
return nil, fmt.Errorf("directory entry for %s has no inode", entry.Name)
}
entries = append(entries, entry)
}
return entries, nil
}
edit in combinators.go at line 277

[2.6661]

[2.6661]

func uint16LE(input []byte) ([]byte, uint16, error) {
if len(input) < 2 {
return input, 0, fmt.Errorf("need 2 bytes to parse a 16-bit integer; only got %d", len(input))
}
return input[2:], binary.LittleEndian.Uint16(input), nil
}