libgo/misc/cgo/test/buildid_linux.go

   1 // Copyright 2014 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 package cgotest
   6
   7 // Test that we have no more than one build ID.  In the past we used
   8 // to generate a separate build ID for each package using cgo, and the
   9 // linker concatenated them all.  We don't want that--we only want
  10 // one.
  11
  12 import (
  13         "bytes"
  14         "debug/elf"
  15         "os"
  16         "testing"
  17 )
  18
  19 func testBuildID(t *testing.T) {
  20         f, err := elf.Open("/proc/self/exe")
  21         if err != nil {
  22                 if os.IsNotExist(err) {
  23                         t.Skip("no /proc/self/exe")
  24                 }
  25                 t.Fatal("opening /proc/self/exe: ", err)
  26         }
  27         defer f.Close()
  28
  29         c := 0
  30         for i, s := range f.Sections {
  31                 if s.Type != elf.SHT_NOTE {
  32                         continue
  33                 }
  34
  35                 d, err := s.Data()
  36                 if err != nil {
  37                         t.Logf("reading data of note section %d: %v", i, err)
  38                         continue
  39                 }
  40
  41                 for len(d) > 0 {
  42
  43                         // ELF standards differ as to the sizes in
  44                         // note sections.  Both the GNU linker and
  45                         // gold always generate 32-bit sizes, so that
  46                         // is what we assume here.
  47
  48                         if len(d) < 12 {
  49                                 t.Logf("note section %d too short (%d < 12)", i, len(d))
  50                                 continue
  51                         }
  52
  53                         namesz := f.ByteOrder.Uint32(d)
  54                         descsz := f.ByteOrder.Uint32(d[4:])
  55                         typ := f.ByteOrder.Uint32(d[8:])
  56
  57                         an := (namesz + 3) &^ 3
  58                         ad := (descsz + 3) &^ 3
  59
  60                         if int(12+an+ad) > len(d) {
  61                                 t.Logf("note section %d too short for header (%d < 12 + align(%d,4) + align(%d,4))", i, len(d), namesz, descsz)
  62                                 continue
  63                         }
  64
  65                         // 3 == NT_GNU_BUILD_ID
  66                         if typ == 3 && namesz == 4 && bytes.Equal(d[12:16], []byte("GNU\000")) {
  67                                 c++
  68                         }
  69
  70                         d = d[12+an+ad:]
  71                 }
  72         }
  73
  74         if c > 1 {
  75                 t.Errorf("found %d build ID notes", c)
  76         }
  77 }