mirror of
https://github.com/rocky-linux/peridot.git
synced 2024-12-26 04:00:55 +00:00
52 lines
1.1 KiB
Go
52 lines
1.1 KiB
Go
package gitdiff
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import (
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"fmt"
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)
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var (
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b85Table map[byte]byte
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b85Alpha = []byte(
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"0123456789" + "ABCDEFGHIJKLMNOPQRSTUVWXYZ" + "abcdefghijklmnopqrstuvwxyz" + "!#$%&()*+-;<=>?@^_`{|}~",
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)
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)
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func init() {
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b85Table = make(map[byte]byte)
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for i, c := range b85Alpha {
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b85Table[c] = byte(i)
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}
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}
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// base85Decode decodes Base85-encoded data from src into dst. It uses the
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// alphabet defined by base85.c in the Git source tree, which appears to be
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// unique. src must contain at least len(dst) bytes of encoded data.
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func base85Decode(dst, src []byte) error {
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var v uint32
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var n, ndst int
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for i, b := range src {
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if b, ok := b85Table[b]; ok {
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v = 85*v + uint32(b)
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n++
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} else {
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return fmt.Errorf("invalid base85 byte at index %d: 0x%X", i, src[i])
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}
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if n == 5 {
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rem := len(dst) - ndst
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for j := 0; j < 4 && j < rem; j++ {
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dst[ndst] = byte(v >> 24)
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ndst++
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v <<= 8
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}
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v = 0
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n = 0
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}
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}
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if n > 0 {
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return fmt.Errorf("base85 data terminated by underpadded sequence")
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}
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if ndst < len(dst) {
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return fmt.Errorf("base85 data underrun: %d < %d", ndst, len(dst))
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}
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return nil
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}
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