libgo/go/syscall/errstr.go

   1 // errstr.go -- Error strings.
   2
   3 // Copyright 2009 The Go Authors. All rights reserved.
   4 // Use of this source code is governed by a BSD-style
   5 // license that can be found in the LICENSE file.
   6
   7 package syscall
   8
   9 import "internal/bytealg"
  10
  11 //extern go_strerror
  12 func go_strerror(_C_int, *byte, Size_t) _C_int
  13
  14 func Errstr(errnum int) string {
  15         for size := 128; ; size *= 2 {
  16                 b := make([]byte, size)
  17                 errno := go_strerror(_C_int(errnum), &b[0], Size_t(len(b)))
  18                 if errno == 0 {
  19                         i := bytealg.IndexByte(b, 0)
  20                         // Lowercase first letter: Bad -> bad, but
  21                         // STREAM -> STREAM.
  22                         if i > 1 && 'A' <= b[0] && b[0] <= 'Z' && 'a' <= b[1] && b[1] <= 'z' {
  23                                 b[0] += 'a' - 'A'
  24                         }
  25                         return string(b[:i])
  26                 }
  27                 if Errno(errno) != ERANGE {
  28                         return "strerror_r failure"
  29                 }
  30         }
  31 }