| // Copyright 2017 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package objabi |
| |
| import ( |
| "fmt" |
| "strconv" |
| "strings" |
| ) |
| |
| // PathToPrefix converts raw string to the prefix that will be used in the |
| // symbol table. All control characters, space, '%' and '"', as well as |
| // non-7-bit clean bytes turn into %xx. The period needs escaping only in the |
| // last segment of the path, and it makes for happier users if we escape that as |
| // little as possible. |
| func PathToPrefix(s string) string { |
| slash := strings.LastIndex(s, "/") |
| // check for chars that need escaping |
| n := 0 |
| for r := 0; r < len(s); r++ { |
| if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F { |
| n++ |
| } |
| } |
| |
| // quick exit |
| if n == 0 { |
| return s |
| } |
| |
| // escape |
| const hex = "0123456789abcdef" |
| p := make([]byte, 0, len(s)+2*n) |
| for r := 0; r < len(s); r++ { |
| if c := s[r]; c <= ' ' || (c == '.' && r > slash) || c == '%' || c == '"' || c >= 0x7F { |
| p = append(p, '%', hex[c>>4], hex[c&0xF]) |
| } else { |
| p = append(p, c) |
| } |
| } |
| |
| return string(p) |
| } |
| |
| // PrefixToPath is the inverse of PathToPrefix, replacing escape sequences with |
| // the original character. |
| func PrefixToPath(s string) (string, error) { |
| percent := strings.IndexByte(s, '%') |
| if percent == -1 { |
| return s, nil |
| } |
| |
| p := make([]byte, 0, len(s)) |
| for i := 0; i < len(s); { |
| if s[i] != '%' { |
| p = append(p, s[i]) |
| i++ |
| continue |
| } |
| if i+2 >= len(s) { |
| // Not enough characters remaining to be a valid escape |
| // sequence. |
| return "", fmt.Errorf("malformed prefix %q: escape sequence must contain two hex digits", s) |
| } |
| |
| b, err := strconv.ParseUint(s[i+1:i+3], 16, 8) |
| if err != nil { |
| // Not a valid escape sequence. |
| return "", fmt.Errorf("malformed prefix %q: escape sequence %q must contain two hex digits", s, s[i:i+3]) |
| } |
| |
| p = append(p, byte(b)) |
| i += 3 |
| } |
| return string(p), nil |
| } |