3960
|
1 /*
|
|
2 * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
|
|
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
|
|
4 *
|
|
5 * This code is free software; you can redistribute it and/or modify it
|
|
6 * under the terms of the GNU General Public License version 2 only, as
|
|
7 * published by the Free Software Foundation.
|
|
8 *
|
|
9 * This code is distributed in the hope that it will be useful, but WITHOUT
|
|
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
|
|
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
12 * version 2 for more details (a copy is included in the LICENSE file that
|
|
13 * accompanied this code).
|
|
14 *
|
|
15 * You should have received a copy of the GNU General Public License version
|
|
16 * 2 along with this work; if not, write to the Free Software Foundation,
|
|
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
|
|
18 *
|
|
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
|
|
20 * or visit www.oracle.com if you need additional information or have any
|
|
21 * questions.
|
|
22 *
|
|
23 */
|
|
24
|
|
25 #include "salibelf.h"
|
|
26 #include <stdlib.h>
|
|
27 #include <unistd.h>
|
|
28 #include <string.h>
|
|
29
|
|
30 extern void print_debug(const char*,...);
|
|
31
|
|
32 // ELF file parsing helpers. Note that we do *not* use libelf here.
|
|
33 int read_elf_header(int fd, ELF_EHDR* ehdr) {
|
|
34 if (pread(fd, ehdr, sizeof (ELF_EHDR), 0) != sizeof (ELF_EHDR) ||
|
|
35 memcmp(&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 ||
|
|
36 ehdr->e_version != EV_CURRENT) {
|
|
37 return 0;
|
|
38 }
|
|
39 return 1;
|
|
40 }
|
|
41
|
|
42 bool is_elf_file(int fd) {
|
|
43 ELF_EHDR ehdr;
|
|
44 return read_elf_header(fd, &ehdr);
|
|
45 }
|
|
46
|
|
47 // read program header table of an ELF file
|
|
48 ELF_PHDR* read_program_header_table(int fd, ELF_EHDR* hdr) {
|
|
49 ELF_PHDR* phbuf = 0;
|
|
50 // allocate memory for program header table
|
|
51 size_t nbytes = hdr->e_phnum * hdr->e_phentsize;
|
|
52
|
|
53 if ((phbuf = (ELF_PHDR*) malloc(nbytes)) == NULL) {
|
|
54 print_debug("can't allocate memory for reading program header table\n");
|
|
55 return NULL;
|
|
56 }
|
|
57
|
|
58 if (pread(fd, phbuf, nbytes, hdr->e_phoff) != nbytes) {
|
|
59 print_debug("ELF file is truncated! can't read program header table\n");
|
|
60 free(phbuf);
|
|
61 return NULL;
|
|
62 }
|
|
63
|
|
64 return phbuf;
|
|
65 }
|
|
66
|
|
67 // read section header table of an ELF file
|
|
68 ELF_SHDR* read_section_header_table(int fd, ELF_EHDR* hdr) {
|
|
69 ELF_SHDR* shbuf = 0;
|
|
70 // allocate memory for section header table
|
|
71 size_t nbytes = hdr->e_shnum * hdr->e_shentsize;
|
|
72
|
|
73 if ((shbuf = (ELF_SHDR*) malloc(nbytes)) == NULL) {
|
|
74 print_debug("can't allocate memory for reading section header table\n");
|
|
75 return NULL;
|
|
76 }
|
|
77
|
|
78 if (pread(fd, shbuf, nbytes, hdr->e_shoff) != nbytes) {
|
|
79 print_debug("ELF file is truncated! can't read section header table\n");
|
|
80 free(shbuf);
|
|
81 return NULL;
|
|
82 }
|
|
83
|
|
84 return shbuf;
|
|
85 }
|
|
86
|
|
87 // read a particular section's data
|
|
88 void* read_section_data(int fd, ELF_EHDR* ehdr, ELF_SHDR* shdr) {
|
|
89 void *buf = NULL;
|
|
90 if (shdr->sh_type == SHT_NOBITS || shdr->sh_size == 0) {
|
|
91 return buf;
|
|
92 }
|
|
93 if ((buf = calloc(shdr->sh_size, 1)) == NULL) {
|
|
94 print_debug("can't allocate memory for reading section data\n");
|
|
95 return NULL;
|
|
96 }
|
|
97 if (pread(fd, buf, shdr->sh_size, shdr->sh_offset) != shdr->sh_size) {
|
|
98 free(buf);
|
|
99 print_debug("section data read failed\n");
|
|
100 return NULL;
|
|
101 }
|
|
102 return buf;
|
|
103 }
|
|
104
|
|
105 uintptr_t find_base_address(int fd, ELF_EHDR* ehdr) {
|
|
106 uintptr_t baseaddr = (uintptr_t)-1;
|
|
107 int cnt;
|
|
108 ELF_PHDR *phbuf, *phdr;
|
|
109
|
|
110 // read program header table
|
|
111 if ((phbuf = read_program_header_table(fd, ehdr)) == NULL) {
|
|
112 goto quit;
|
|
113 }
|
|
114
|
|
115 // the base address of a shared object is the lowest vaddr of
|
|
116 // its loadable segments (PT_LOAD)
|
|
117 for (phdr = phbuf, cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) {
|
|
118 if (phdr->p_type == PT_LOAD && phdr->p_vaddr < baseaddr) {
|
|
119 baseaddr = phdr->p_vaddr;
|
|
120 }
|
|
121 }
|
|
122
|
|
123 quit:
|
|
124 if (phbuf) free(phbuf);
|
|
125 return baseaddr;
|
|
126 }
|