summaryrefslogtreecommitdiff
path: root/elf.c
blob: 63c940394af55c0bdc63b0b3a05994c3c63daf62 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <elf.h>
#if defined(HAVE_SYS_LINK_H)
#  include <sys/link.h> /* Find DT_RPATH on Solaris 2.6 */
#endif /*  HAVE_SYS_LINK_H */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include "protos.h"

int
elf_open(const char *filename, int flags, Elf_Ehdr *ehdr)
{
   int fd;

   fd = open(filename, flags);
   if (fd == -1)
   {
     perror ("open");
     return -1;
   }

   if (read(fd, ehdr, sizeof(*ehdr)) != sizeof(*ehdr))
   {
     perror ("reading header");
     close(fd);
     return -1;
   }

   if (0 != memcmp(ehdr->e_ident, ELFMAG, SELFMAG) ||
       ehdr->e_ident[EI_CLASS] != ELFCLASS ||
       ehdr->e_ident[EI_DATA] != ELFDATA2 ||
       ehdr->e_ident[EI_VERSION] != EV_CURRENT)
   {
     fprintf(stderr,
#ifdef WORDS_BIGENDIAN
             "`%s' probably isn't a %d-bit MSB-first ELF file.\n",
#else /* not WORD_BIGENDIAN */
             "`%s' probably isn't a %d-bit LSB-first ELF file.\n",
#endif /* not WORD_BIGENDIAN */
             filename, SIZEOF_VOID_P * 8);
     close(fd);
     errno = ENOEXEC; /* Hm, is this the best errno code to use? */
     return -1;
   }

   if (ehdr->e_phentsize != sizeof(Elf_Phdr))
   {
     fprintf(stderr, "section size was read as %d, not %d!\n",
            ehdr->e_phentsize, sizeof(Elf_Phdr));
     close(fd);
     return -1;
   }
   return fd;
}

int
elf_find_dynamic_section(int fd, Elf_Ehdr *ehdr, Elf_Phdr *phdr)
{
  int i;
  if (lseek(fd, ehdr->e_phoff, SEEK_SET) == -1)
  {
    perror ("positioning for sections");
    return 1;
  }

  for (i = 0; i < ehdr->e_phnum; i++)
  {
    if (read(fd, phdr, sizeof(*phdr)) != sizeof(*phdr))
    {
      perror ("reading section header");
      return 1;
    }
    if (phdr->p_type == PT_DYNAMIC)
      break;
  }
  if (i == ehdr->e_phnum)
    {
      fprintf (stderr, "No dynamic section found.\n");
      return 2;
    }

  if (0 == phdr->p_filesz)
    {
      fprintf (stderr, "Length of dynamic section is zero.\n");
      return 3;
    }

  return 0;
}

void
elf_close(int fd)
{
  close(fd);
}

const char *
elf_tagname(int tag)
{
  switch (tag) {
  case DT_RPATH:
    return "RPATH";
    break;
#if defined(DT_RUNPATH)
  case DT_RUNPATH:
    return "RUNPATH";
    break;
#endif /* DT_RUNPATH */
  }
  return "UNKNOWN";
}

int
elf_dynpath_tag(int tag)
{
  return ( tag == DT_RPATH
#if defined(DT_RUNPATH)
           || tag == DT_RUNPATH
#endif /* DT_RUNPATH */
           );
}