mirror of
https://github.com/wader/fq.git
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b08ef00dd1
Replaces []Format with a Group type. A bit more type safe. Breaking change for RegisterFormat, now takes a first argument that is a "single" format group. Lots of naming cleanup. This is also preparation for decode group argument which will enable doing intresting probing, ex a format decoder could know it's decode as part of probe group (html could be probed possibly), or have "arg probe" group for decoder who inspect args to know if they should probe (-d /path/to/schema etc) to enable nice CLI-ergonomics.
99 lines
2.1 KiB
Go
99 lines
2.1 KiB
Go
package bencode
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// https://wiki.theory.org/BitTorrentSpecification#Bencoding
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import (
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"embed"
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"strconv"
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"github.com/wader/fq/format"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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//go:embed bencode.jq
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//go:embed bencode.md
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var bencodeFS embed.FS
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func init() {
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interp.RegisterFormat(
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format.Bencode,
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&decode.Format{
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Description: "BitTorrent bencoding",
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DecodeFn: decodeBencode,
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Functions: []string{"torepr"},
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})
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interp.RegisterFS(bencodeFS)
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}
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var typeToNames = scalar.StrMapSymStr{
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"d": "dictionary",
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"i": "integer",
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"l": "list",
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"0": "string",
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"1": "string",
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"2": "string",
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"3": "string",
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"4": "string",
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"5": "string",
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"6": "string",
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"7": "string",
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"8": "string",
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"9": "string",
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}
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func decodeStrIntUntil(b byte) func(d *decode.D) int64 {
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return func(d *decode.D) int64 {
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// 21 is sign + longest 64 bit in base 10
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i := d.PeekFindByte(b, 21)
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if i == -1 {
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d.Fatalf("decodeStrIntUntil: failed to find %v", b)
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}
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s := d.UTF8(int(i))
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n, err := strconv.ParseInt(s, 10, 64)
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if err != nil {
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d.Fatalf("decodeStrIntUntil: %q: %s", s, err)
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}
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return n
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}
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}
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func decodeBencodeValue(d *decode.D) {
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typ := d.FieldUTF8("type", 1, typeToNames)
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switch typ {
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case "0", "1", "2", "3", "4", "5", "6", "7", "8", "9":
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d.SeekRel(-8)
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length := d.FieldSintFn("length", decodeStrIntUntil(':'))
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d.FieldUTF8("separator", 1, d.StrAssert(":"))
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d.FieldUTF8("value", int(length))
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case "i":
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d.FieldSintFn("value", decodeStrIntUntil('e'))
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d.FieldUTF8("end", 1, d.StrAssert("e"))
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case "l":
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d.FieldArray("values", func(d *decode.D) {
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for d.PeekUintBits(8) != 'e' {
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d.FieldStruct("value", decodeBencodeValue)
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}
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})
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d.FieldUTF8("end", 1, d.StrAssert("e"))
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case "d":
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d.FieldArray("pairs", func(d *decode.D) {
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for d.PeekUintBits(8) != 'e' {
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d.FieldStruct("pair", func(d *decode.D) {
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d.FieldStruct("key", decodeBencodeValue)
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d.FieldStruct("value", decodeBencodeValue)
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})
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}
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})
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d.FieldUTF8("end", 1, d.StrAssert("e"))
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default:
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d.Fatalf("unknown type %v", typ)
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}
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}
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func decodeBencode(d *decode.D) any {
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decodeBencodeValue(d)
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return nil
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}
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