diff options
Diffstat (limited to 'vendor/gopkg.in/src-d/go-git.v4/utils/binary/read.go')
-rw-r--r-- | vendor/gopkg.in/src-d/go-git.v4/utils/binary/read.go | 180 |
1 files changed, 0 insertions, 180 deletions
diff --git a/vendor/gopkg.in/src-d/go-git.v4/utils/binary/read.go b/vendor/gopkg.in/src-d/go-git.v4/utils/binary/read.go deleted file mode 100644 index 12e57c300e..0000000000 --- a/vendor/gopkg.in/src-d/go-git.v4/utils/binary/read.go +++ /dev/null @@ -1,180 +0,0 @@ -// Package binary implements sintax-sugar functions on top of the standard -// library binary package -package binary - -import ( - "bufio" - "encoding/binary" - "io" - - "gopkg.in/src-d/go-git.v4/plumbing" -) - -// Read reads structured binary data from r into data. Bytes are read and -// decoded in BigEndian order -// https://golang.org/pkg/encoding/binary/#Read -func Read(r io.Reader, data ...interface{}) error { - for _, v := range data { - if err := binary.Read(r, binary.BigEndian, v); err != nil { - return err - } - } - - return nil -} - -// ReadUntil reads from r untin delim is found -func ReadUntil(r io.Reader, delim byte) ([]byte, error) { - if bufr, ok := r.(*bufio.Reader); ok { - return ReadUntilFromBufioReader(bufr, delim) - } - - var buf [1]byte - value := make([]byte, 0, 16) - for { - if _, err := io.ReadFull(r, buf[:]); err != nil { - if err == io.EOF { - return nil, err - } - - return nil, err - } - - if buf[0] == delim { - return value, nil - } - - value = append(value, buf[0]) - } -} - -// ReadUntilFromBufioReader is like bufio.ReadBytes but drops the delimiter -// from the result. -func ReadUntilFromBufioReader(r *bufio.Reader, delim byte) ([]byte, error) { - value, err := r.ReadBytes(delim) - if err != nil || len(value) == 0 { - return nil, err - } - - return value[:len(value)-1], nil -} - -// ReadVariableWidthInt reads and returns an int in Git VLQ special format: -// -// Ordinary VLQ has some redundancies, example: the number 358 can be -// encoded as the 2-octet VLQ 0x8166 or the 3-octet VLQ 0x808166 or the -// 4-octet VLQ 0x80808166 and so forth. -// -// To avoid these redundancies, the VLQ format used in Git removes this -// prepending redundancy and extends the representable range of shorter -// VLQs by adding an offset to VLQs of 2 or more octets in such a way -// that the lowest possible value for such an (N+1)-octet VLQ becomes -// exactly one more than the maximum possible value for an N-octet VLQ. -// In particular, since a 1-octet VLQ can store a maximum value of 127, -// the minimum 2-octet VLQ (0x8000) is assigned the value 128 instead of -// 0. Conversely, the maximum value of such a 2-octet VLQ (0xff7f) is -// 16511 instead of just 16383. Similarly, the minimum 3-octet VLQ -// (0x808000) has a value of 16512 instead of zero, which means -// that the maximum 3-octet VLQ (0xffff7f) is 2113663 instead of -// just 2097151. And so forth. -// -// This is how the offset is saved in C: -// -// dheader[pos] = ofs & 127; -// while (ofs >>= 7) -// dheader[--pos] = 128 | (--ofs & 127); -// -func ReadVariableWidthInt(r io.Reader) (int64, error) { - var c byte - if err := Read(r, &c); err != nil { - return 0, err - } - - var v = int64(c & maskLength) - for c&maskContinue > 0 { - v++ - if err := Read(r, &c); err != nil { - return 0, err - } - - v = (v << lengthBits) + int64(c&maskLength) - } - - return v, nil -} - -const ( - maskContinue = uint8(128) // 1000 000 - maskLength = uint8(127) // 0111 1111 - lengthBits = uint8(7) // subsequent bytes has 7 bits to store the length -) - -// ReadUint64 reads 8 bytes and returns them as a BigEndian uint32 -func ReadUint64(r io.Reader) (uint64, error) { - var v uint64 - if err := binary.Read(r, binary.BigEndian, &v); err != nil { - return 0, err - } - - return v, nil -} - -// ReadUint32 reads 4 bytes and returns them as a BigEndian uint32 -func ReadUint32(r io.Reader) (uint32, error) { - var v uint32 - if err := binary.Read(r, binary.BigEndian, &v); err != nil { - return 0, err - } - - return v, nil -} - -// ReadUint16 reads 2 bytes and returns them as a BigEndian uint16 -func ReadUint16(r io.Reader) (uint16, error) { - var v uint16 - if err := binary.Read(r, binary.BigEndian, &v); err != nil { - return 0, err - } - - return v, nil -} - -// ReadHash reads a plumbing.Hash from r -func ReadHash(r io.Reader) (plumbing.Hash, error) { - var h plumbing.Hash - if err := binary.Read(r, binary.BigEndian, h[:]); err != nil { - return plumbing.ZeroHash, err - } - - return h, nil -} - -const sniffLen = 8000 - -// IsBinary detects if data is a binary value based on: -// http://git.kernel.org/cgit/git/git.git/tree/xdiff-interface.c?id=HEAD#n198 -func IsBinary(r io.Reader) (bool, error) { - reader := bufio.NewReader(r) - c := 0 - for { - if c == sniffLen { - break - } - - b, err := reader.ReadByte() - if err == io.EOF { - break - } - if err != nil { - return false, err - } - - if b == byte(0) { - return true, nil - } - - c++ - } - - return false, nil -} |