1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/agent/src/os/bsd/salibelf.c Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,126 @@
1.4 +/*
1.5 + * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "salibelf.h"
1.29 +#include <stdlib.h>
1.30 +#include <unistd.h>
1.31 +#include <string.h>
1.32 +
1.33 +extern void print_debug(const char*,...);
1.34 +
1.35 +// ELF file parsing helpers. Note that we do *not* use libelf here.
1.36 +int read_elf_header(int fd, ELF_EHDR* ehdr) {
1.37 + if (pread(fd, ehdr, sizeof (ELF_EHDR), 0) != sizeof (ELF_EHDR) ||
1.38 + memcmp(&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 ||
1.39 + ehdr->e_version != EV_CURRENT) {
1.40 + return 0;
1.41 + }
1.42 + return 1;
1.43 +}
1.44 +
1.45 +bool is_elf_file(int fd) {
1.46 + ELF_EHDR ehdr;
1.47 + return read_elf_header(fd, &ehdr);
1.48 +}
1.49 +
1.50 +// read program header table of an ELF file
1.51 +ELF_PHDR* read_program_header_table(int fd, ELF_EHDR* hdr) {
1.52 + ELF_PHDR* phbuf = 0;
1.53 + // allocate memory for program header table
1.54 + size_t nbytes = hdr->e_phnum * hdr->e_phentsize;
1.55 +
1.56 + if ((phbuf = (ELF_PHDR*) malloc(nbytes)) == NULL) {
1.57 + print_debug("can't allocate memory for reading program header table\n");
1.58 + return NULL;
1.59 + }
1.60 +
1.61 + if (pread(fd, phbuf, nbytes, hdr->e_phoff) != nbytes) {
1.62 + print_debug("ELF file is truncated! can't read program header table\n");
1.63 + free(phbuf);
1.64 + return NULL;
1.65 + }
1.66 +
1.67 + return phbuf;
1.68 +}
1.69 +
1.70 +// read section header table of an ELF file
1.71 +ELF_SHDR* read_section_header_table(int fd, ELF_EHDR* hdr) {
1.72 + ELF_SHDR* shbuf = 0;
1.73 + // allocate memory for section header table
1.74 + size_t nbytes = hdr->e_shnum * hdr->e_shentsize;
1.75 +
1.76 + if ((shbuf = (ELF_SHDR*) malloc(nbytes)) == NULL) {
1.77 + print_debug("can't allocate memory for reading section header table\n");
1.78 + return NULL;
1.79 + }
1.80 +
1.81 + if (pread(fd, shbuf, nbytes, hdr->e_shoff) != nbytes) {
1.82 + print_debug("ELF file is truncated! can't read section header table\n");
1.83 + free(shbuf);
1.84 + return NULL;
1.85 + }
1.86 +
1.87 + return shbuf;
1.88 +}
1.89 +
1.90 +// read a particular section's data
1.91 +void* read_section_data(int fd, ELF_EHDR* ehdr, ELF_SHDR* shdr) {
1.92 + void *buf = NULL;
1.93 + if (shdr->sh_type == SHT_NOBITS || shdr->sh_size == 0) {
1.94 + return buf;
1.95 + }
1.96 + if ((buf = calloc(shdr->sh_size, 1)) == NULL) {
1.97 + print_debug("can't allocate memory for reading section data\n");
1.98 + return NULL;
1.99 + }
1.100 + if (pread(fd, buf, shdr->sh_size, shdr->sh_offset) != shdr->sh_size) {
1.101 + free(buf);
1.102 + print_debug("section data read failed\n");
1.103 + return NULL;
1.104 + }
1.105 + return buf;
1.106 +}
1.107 +
1.108 +uintptr_t find_base_address(int fd, ELF_EHDR* ehdr) {
1.109 + uintptr_t baseaddr = (uintptr_t)-1;
1.110 + int cnt;
1.111 + ELF_PHDR *phbuf, *phdr;
1.112 +
1.113 + // read program header table
1.114 + if ((phbuf = read_program_header_table(fd, ehdr)) == NULL) {
1.115 + goto quit;
1.116 + }
1.117 +
1.118 + // the base address of a shared object is the lowest vaddr of
1.119 + // its loadable segments (PT_LOAD)
1.120 + for (phdr = phbuf, cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) {
1.121 + if (phdr->p_type == PT_LOAD && phdr->p_vaddr < baseaddr) {
1.122 + baseaddr = phdr->p_vaddr;
1.123 + }
1.124 + }
1.125 +
1.126 +quit:
1.127 + if (phbuf) free(phbuf);
1.128 + return baseaddr;
1.129 +}
