mirror of
https://github.com/bluekeyes/go-gitdiff
synced 2026-06-08 13:18:30 +00:00
Billy Keyes
62569e0d07
These are fairly basic as the decoder is also exercised by the fragment parsing tests, but they cover some errror cases that may not be covered otherwise.
53 lines
1.1 KiB
Go
53 lines
1.1 KiB
Go
package gitdiff
|
|
|
|
import (
|
|
"fmt"
|
|
)
|
|
|
|
var (
|
|
b85Table map[byte]byte
|
|
b85Alpha = []byte(
|
|
"0123456789" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "!#$%&()*+-;<=>?@^_`{|}~",
|
|
)
|
|
)
|
|
|
|
func init() {
|
|
b85Table = make(map[byte]byte)
|
|
for i, c := range b85Alpha {
|
|
b85Table[c] = byte(i)
|
|
}
|
|
}
|
|
|
|
// base85Decode decodes Base85-encoded data from src into dst. It uses the
|
|
// alphabet defined by base85.c in the Git source tree, which appears to be
|
|
// unique. src must contain at least len(dst) bytes of encoded data.
|
|
func base85Decode(dst, src []byte) error {
|
|
var v uint32
|
|
var n, ndst int
|
|
for i, b := range src {
|
|
if b, ok := b85Table[b]; ok {
|
|
v = 85*v + uint32(b)
|
|
n++
|
|
} else {
|
|
return fmt.Errorf("invalid base85 byte at index %d: 0x%x", i, b)
|
|
}
|
|
if n == 5 {
|
|
rem := len(dst) - ndst
|
|
for j := 0; j < 4 && j < rem; j++ {
|
|
dst[ndst] = byte(v >> 24)
|
|
ndst++
|
|
v <<= 8
|
|
}
|
|
v = 0
|
|
n = 0
|
|
}
|
|
}
|
|
if n > 0 {
|
|
return fmt.Errorf("base85 data terminated by underpadded sequence")
|
|
}
|
|
if ndst < len(dst) {
|
|
return fmt.Errorf("base85 data underrun: %d < %d", ndst, len(dst))
|
|
}
|
|
return nil
|
|
}
|