elfxx.c revision 4409fc61d874df46a483e348405be1183cfd8c4b 
1/* libunwind - a platform-independent unwind library
2   Copyright (C) 2003 Hewlett-Packard Co
3	Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5This file is part of libunwind.
6
7Permission is hereby granted, free of charge, to any person obtaining
8a copy of this software and associated documentation files (the
9"Software"), to deal in the Software without restriction, including
10without limitation the rights to use, copy, modify, merge, publish,
11distribute, sublicense, and/or sell copies of the Software, and to
12permit persons to whom the Software is furnished to do so, subject to
13the following conditions:
14
15The above copyright notice and this permission notice shall be
16included in all copies or substantial portions of the Software.
17
18THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
22LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
23OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
24WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
25
26#include <stdio.h>
27#include <string.h>
28#include <unistd.h>
29
30#include <sys/types.h>
31
32#include "tdep.h"
33
34extern HIDDEN int
35elfW (valid_object) (struct elf_image *ei)
36{
37  if (ei->size <= EI_CLASS)
38    return 0;
39
40  return (memcmp (ei->image, ELFMAG, SELFMAG) == 0
41	  && ((uint8_t *) ei->image)[EI_CLASS] == ELF_CLASS);
42}
43
44
45static int
46elfW (lookup_symbol) (unw_word_t ip, struct elf_image *ei,
47		      ElfW (Addr) load_offset,
48		      char *buf, size_t buf_len, unw_word_t *offp)
49{
50  size_t syment_size, str_size;
51  ElfW (Ehdr) *ehdr = ei->image;
52  ElfW (Sym) *sym, *symtab, *symtab_end;
53  ElfW (Off) soff, str_soff;
54  ElfW (Shdr) *shdr, *str_shdr;
55  ElfW (Addr) val, min_dist = ~(ElfW (Addr))0;
56  int i, ret = 0;
57  char *strtab;
58
59  if (!elfW (valid_object) (ei))
60    return -UNW_ENOINFO;
61
62  soff = ehdr->e_shoff;
63  if (soff + ehdr->e_shnum * ehdr->e_shentsize > ei->size)
64    {
65      debug (1, "%s: section table outside of image? (%lu > %lu)\n",
66	     __FUNCTION__, soff + ehdr->e_shnum * ehdr->e_shentsize,
67	     ei->size);
68      return -UNW_ENOINFO;
69    }
70
71  shdr = (ElfW (Shdr) *) ((char *) ei->image + soff);
72
73  for (i = 0; i < ehdr->e_shnum; ++i)
74    {
75      switch (shdr->sh_type)
76	{
77	case SHT_SYMTAB:
78	case SHT_DYNSYM:
79	  symtab = (ElfW (Sym) *) ((char *) ei->image + shdr->sh_offset);
80	  symtab_end = (ElfW (Sym) *) ((char *) symtab + shdr->sh_size);
81	  syment_size = shdr->sh_entsize;
82
83	  str_soff = soff + (shdr->sh_link * ehdr->e_shentsize);
84	  if (str_soff + ehdr->e_shentsize >= ei->size)
85	    {
86	      debug (1, "%s: string table outside of image? (%lu >= %lu)\n",
87		     __FUNCTION__, str_soff + ehdr->e_shentsize, ei->size);
88	      break;
89	    }
90	  str_shdr = (ElfW (Shdr) *) ((char *) ei->image + str_soff);
91	  str_size = str_shdr->sh_size;
92	  strtab = (char *) ei->image + str_shdr->sh_offset;
93
94	  debug (160, "symtab=0x%lx[%d], strtab=0x%lx\n", shdr->sh_offset,
95		 shdr->sh_type, str_shdr->sh_offset);
96
97	  for (sym = symtab;
98	       sym < symtab_end;
99	       sym = (ElfW (Sym) *) ((char *) sym + syment_size))
100	    {
101	      if (ELFW (ST_TYPE) (sym->st_info) == STT_FUNC
102		  && sym->st_shndx != SHN_UNDEF)
103		{
104		  val = sym->st_value;
105		  if (sym->st_shndx != SHN_ABS)
106		    val += load_offset;
107		  debug (160, "0x%016lx info=0x%02x %s\n",
108			 val, sym->st_info, strtab + sym->st_name);
109
110		  if ((ElfW (Addr)) (ip - val) < min_dist)
111		    {
112		      min_dist = (ElfW (Addr)) (ip - val);
113		      strncpy (buf, strtab + sym->st_name, buf_len);
114		      buf[buf_len - 1] = '\0';
115		      if (strlen (strtab + sym->st_name) >= buf_len)
116			ret = -UNW_ENOMEM;
117		    }
118		}
119	    }
120	  break;
121
122	default:
123	  break;
124	}
125      shdr = (ElfW (Shdr) *) (((char *) shdr) + ehdr->e_shentsize);
126    }
127  if (min_dist >= ei->size)
128    return -UNW_ENOINFO;		/* not found */
129  if (offp)
130    *offp = min_dist;
131  return ret;
132}
133
134/* Find the ELF image that contains IP and return the "closest"
135   procedure name, if there is one.  With some caching, this could be
136   sped up greatly, but until an application materializes that's
137   sensitive to the performance of this routine, why bother...  */
138
139HIDDEN int
140elfW (get_proc_name) (pid_t pid, unw_word_t ip, char *buf, size_t buf_len,
141		      unw_word_t *offp)
142{
143  unsigned long segbase, mapoff;
144  ElfW (Addr) load_offset = 0;
145  struct elf_image ei;
146  ElfW (Ehdr) *ehdr;
147  ElfW (Phdr) *phdr;
148  int i, ret;
149
150  ret = tdep_get_elf_image (&ei, pid, ip, &segbase, &mapoff);
151  if (ret < 0)
152    return ret;
153
154  ehdr = ei.image;
155  phdr = (ElfW (Phdr) *) ((char *) ei.image + ehdr->e_phoff);
156
157  for (i = 0; i < ehdr->e_phnum; ++i)
158    if (phdr[i].p_type == PT_LOAD && phdr[i].p_offset == mapoff)
159      {
160	load_offset = segbase - phdr[i].p_vaddr;
161	break;
162      }
163
164  ret = elfW (lookup_symbol) (ip, &ei, load_offset, buf, buf_len, offp);
165
166  munmap (ei.image, ei.size);
167  ei.image = NULL;
168
169  return ret;
170}
171