1 /* ELF core file support for BFD.
2 Copyright (C) 1995-2014 Free Software Foundation, Inc.
3
4 This file is part of BFD, the Binary File Descriptor library.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
19 MA 02110-1301, USA. */
20
21 char*
elf_core_file_failing_command(bfd * abfd)22 elf_core_file_failing_command (bfd *abfd)
23 {
24 return elf_tdata (abfd)->core->command;
25 }
26
27 int
elf_core_file_failing_signal(bfd * abfd)28 elf_core_file_failing_signal (bfd *abfd)
29 {
30 return elf_tdata (abfd)->core->signal;
31 }
32
33 int
elf_core_file_pid(bfd * abfd)34 elf_core_file_pid (bfd *abfd)
35 {
36 return elf_tdata (abfd)->core->pid;
37 }
38
39 bfd_boolean
elf_core_file_matches_executable_p(bfd * core_bfd,bfd * exec_bfd)40 elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd)
41 {
42 char* corename;
43
44 /* xvecs must match if both are ELF files for the same target. */
45
46 if (core_bfd->xvec != exec_bfd->xvec)
47 {
48 bfd_set_error (bfd_error_system_call);
49 return FALSE;
50 }
51
52 /* See if the name in the corefile matches the executable name. */
53 corename = elf_tdata (core_bfd)->core->program;
54 if (corename != NULL)
55 {
56 const char* execname = strrchr (exec_bfd->filename, '/');
57
58 execname = execname ? execname + 1 : exec_bfd->filename;
59
60 if (strcmp (execname, corename) != 0)
61 return FALSE;
62 }
63
64 return TRUE;
65 }
66
67 /* Core files are simply standard ELF formatted files that partition
68 the file using the execution view of the file (program header table)
69 rather than the linking view. In fact, there is no section header
70 table in a core file.
71
72 The process status information (including the contents of the general
73 register set) and the floating point register set are stored in a
74 segment of type PT_NOTE. We handcraft a couple of extra bfd sections
75 that allow standard bfd access to the general registers (.reg) and the
76 floating point registers (.reg2). */
77
78 const bfd_target *
elf_core_file_p(bfd * abfd)79 elf_core_file_p (bfd *abfd)
80 {
81 Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */
82 Elf_Internal_Ehdr *i_ehdrp; /* Elf file header, internal form. */
83 Elf_Internal_Phdr *i_phdrp; /* Elf program header, internal form. */
84 unsigned int phindex;
85 const struct elf_backend_data *ebd;
86 bfd_size_type amt;
87
88 /* Read in the ELF header in external format. */
89 if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
90 {
91 if (bfd_get_error () != bfd_error_system_call)
92 goto wrong;
93 else
94 goto fail;
95 }
96
97 /* Check the magic number. */
98 if (! elf_file_p (&x_ehdr))
99 goto wrong;
100
101 /* FIXME: Check EI_VERSION here ! */
102
103 /* Check the address size ("class"). */
104 if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
105 goto wrong;
106
107 /* Check the byteorder. */
108 switch (x_ehdr.e_ident[EI_DATA])
109 {
110 case ELFDATA2MSB: /* Big-endian. */
111 if (! bfd_big_endian (abfd))
112 goto wrong;
113 break;
114 case ELFDATA2LSB: /* Little-endian. */
115 if (! bfd_little_endian (abfd))
116 goto wrong;
117 break;
118 default:
119 goto wrong;
120 }
121
122 /* Give abfd an elf_obj_tdata. */
123 if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
124 goto fail;
125
126 /* Swap in the rest of the header, now that we have the byte order. */
127 i_ehdrp = elf_elfheader (abfd);
128 elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);
129
130 #if DEBUG & 1
131 elf_debug_file (i_ehdrp);
132 #endif
133
134 ebd = get_elf_backend_data (abfd);
135
136 /* Check that the ELF e_machine field matches what this particular
137 BFD format expects. */
138
139 if (ebd->elf_machine_code != i_ehdrp->e_machine
140 && (ebd->elf_machine_alt1 == 0
141 || i_ehdrp->e_machine != ebd->elf_machine_alt1)
142 && (ebd->elf_machine_alt2 == 0
143 || i_ehdrp->e_machine != ebd->elf_machine_alt2))
144 {
145 const bfd_target * const *target_ptr;
146
147 if (ebd->elf_machine_code != EM_NONE)
148 goto wrong;
149
150 /* This is the generic ELF target. Let it match any ELF target
151 for which we do not have a specific backend. */
152
153 for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
154 {
155 const struct elf_backend_data *back;
156
157 if ((*target_ptr)->flavour != bfd_target_elf_flavour)
158 continue;
159 back = xvec_get_elf_backend_data (*target_ptr);
160 if (back->s->arch_size != ARCH_SIZE)
161 continue;
162 if (back->elf_machine_code == i_ehdrp->e_machine
163 || (back->elf_machine_alt1 != 0
164 && i_ehdrp->e_machine == back->elf_machine_alt1)
165 || (back->elf_machine_alt2 != 0
166 && i_ehdrp->e_machine == back->elf_machine_alt2))
167 {
168 /* target_ptr is an ELF backend which matches this
169 object file, so reject the generic ELF target. */
170 goto wrong;
171 }
172 }
173 }
174
175 /* If there is no program header, or the type is not a core file, then
176 we are hosed. */
177 if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
178 goto wrong;
179
180 /* Does BFD's idea of the phdr size match the size
181 recorded in the file? */
182 if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
183 goto wrong;
184
185 /* If the program header count is PN_XNUM(0xffff), the actual
186 count is in the first section header. */
187 if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM)
188 {
189 Elf_External_Shdr x_shdr;
190 Elf_Internal_Shdr i_shdr;
191 bfd_signed_vma where = i_ehdrp->e_shoff;
192
193 if (where != (file_ptr) where)
194 goto wrong;
195
196 /* Seek to the section header table in the file. */
197 if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
198 goto fail;
199
200 /* Read the first section header at index 0, and convert to internal
201 form. */
202 if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
203 goto fail;
204 elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);
205
206 if (i_shdr.sh_info != 0)
207 {
208 i_ehdrp->e_phnum = i_shdr.sh_info;
209 if (i_ehdrp->e_phnum != i_shdr.sh_info)
210 goto wrong;
211 }
212 }
213
214 /* Sanity check that we can read all of the program headers.
215 It ought to be good enough to just read the last one. */
216 if (i_ehdrp->e_phnum > 1)
217 {
218 Elf_External_Phdr x_phdr;
219 Elf_Internal_Phdr i_phdr;
220 bfd_signed_vma where;
221
222 /* Check that we don't have a totally silly number of
223 program headers. */
224 if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
225 || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
226 goto wrong;
227
228 where = i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr);
229 if (where != (file_ptr) where)
230 goto wrong;
231 if ((bfd_size_type) where <= i_ehdrp->e_phoff)
232 goto wrong;
233
234 if (bfd_seek (abfd, (file_ptr) where, SEEK_SET) != 0)
235 goto fail;
236 if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
237 goto fail;
238 }
239
240 /* Move to the start of the program headers. */
241 if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
242 goto wrong;
243
244 /* Allocate space for the program headers. */
245 amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
246 i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
247 if (!i_phdrp)
248 goto fail;
249
250 elf_tdata (abfd)->phdr = i_phdrp;
251
252 /* Read and convert to internal form. */
253 for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
254 {
255 Elf_External_Phdr x_phdr;
256
257 if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
258 goto fail;
259
260 elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
261 }
262
263 /* Set the machine architecture. Do this before processing the
264 program headers since we need to know the architecture type
265 when processing the notes of some systems' core files. */
266 if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
267 /* It's OK if this fails for the generic target. */
268 && ebd->elf_machine_code != EM_NONE)
269 goto fail;
270
271 /* Let the backend double check the format and override global
272 information. We do this before processing the program headers
273 to allow the correct machine (as opposed to just the default
274 machine) to be set, making it possible for grok_prstatus and
275 grok_psinfo to rely on the mach setting. */
276 if (ebd->elf_backend_object_p != NULL
277 && ! ebd->elf_backend_object_p (abfd))
278 goto wrong;
279
280 /* Process each program header. */
281 for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
282 if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
283 goto fail;
284
285 /* Check for core truncation. */
286 {
287 bfd_size_type high = 0;
288 struct stat statbuf;
289 for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
290 {
291 Elf_Internal_Phdr *p = i_phdrp + phindex;
292 if (p->p_filesz)
293 {
294 bfd_size_type current = p->p_offset + p->p_filesz;
295 if (high < current)
296 high = current;
297 }
298 }
299 if (bfd_stat (abfd, &statbuf) == 0)
300 {
301 if ((bfd_size_type) statbuf.st_size < high)
302 {
303 (*_bfd_error_handler)
304 (_("Warning: %B is truncated: expected core file "
305 "size >= %lu, found: %lu."),
306 abfd, (unsigned long) high, (unsigned long) statbuf.st_size);
307 }
308 }
309 }
310
311 /* Save the entry point from the ELF header. */
312 bfd_get_start_address (abfd) = i_ehdrp->e_entry;
313 return abfd->xvec;
314
315 wrong:
316 bfd_set_error (bfd_error_wrong_format);
317 fail:
318 return NULL;
319 }
320