aoqi@0: /*
aoqi@0:  * Copyright (c) 2003, 2006, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #include "salibelf.h"
aoqi@0: #include <stdlib.h>
aoqi@0: #include <unistd.h>
aoqi@0: #include <string.h>
aoqi@0: 
aoqi@0: extern void print_debug(const char*,...);
aoqi@0: 
aoqi@0: // ELF file parsing helpers. Note that we do *not* use libelf here.
aoqi@0: int read_elf_header(int fd, ELF_EHDR* ehdr) {
aoqi@0:    if (pread(fd, ehdr, sizeof (ELF_EHDR), 0) != sizeof (ELF_EHDR) ||
aoqi@0:             memcmp(&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 ||
aoqi@0:             ehdr->e_version != EV_CURRENT) {
aoqi@0:         return 0;
aoqi@0:    }
aoqi@0:    return 1;
aoqi@0: }
aoqi@0: 
aoqi@0: bool is_elf_file(int fd) {
aoqi@0:    ELF_EHDR ehdr;
aoqi@0:    return read_elf_header(fd, &ehdr);
aoqi@0: }
aoqi@0: 
aoqi@0: // read program header table of an ELF file
aoqi@0: ELF_PHDR* read_program_header_table(int fd, ELF_EHDR* hdr) {
aoqi@0:    ELF_PHDR* phbuf = 0;
aoqi@0:    // allocate memory for program header table
aoqi@0:    size_t nbytes = hdr->e_phnum * hdr->e_phentsize;
aoqi@0: 
aoqi@0:    if ((phbuf = (ELF_PHDR*) malloc(nbytes)) == NULL) {
aoqi@0:       print_debug("can't allocate memory for reading program header table\n");
aoqi@0:       return NULL;
aoqi@0:    }
aoqi@0: 
aoqi@0:    if (pread(fd, phbuf, nbytes, hdr->e_phoff) != nbytes) {
aoqi@0:       print_debug("ELF file is truncated! can't read program header table\n");
aoqi@0:       free(phbuf);
aoqi@0:       return NULL;
aoqi@0:    }
aoqi@0: 
aoqi@0:    return phbuf;
aoqi@0: }
aoqi@0: 
aoqi@0: // read section header table of an ELF file
aoqi@0: ELF_SHDR* read_section_header_table(int fd, ELF_EHDR* hdr) {
aoqi@0:    ELF_SHDR* shbuf = 0;
aoqi@0:    // allocate memory for section header table
aoqi@0:    size_t nbytes = hdr->e_shnum * hdr->e_shentsize;
aoqi@0: 
aoqi@0:    if ((shbuf = (ELF_SHDR*) malloc(nbytes)) == NULL) {
aoqi@0:       print_debug("can't allocate memory for reading section header table\n");
aoqi@0:       return NULL;
aoqi@0:    }
aoqi@0: 
aoqi@0:    if (pread(fd, shbuf, nbytes, hdr->e_shoff) != nbytes) {
aoqi@0:       print_debug("ELF file is truncated! can't read section header table\n");
aoqi@0:       free(shbuf);
aoqi@0:       return NULL;
aoqi@0:    }
aoqi@0: 
aoqi@0:    return shbuf;
aoqi@0: }
aoqi@0: 
aoqi@0: // read a particular section's data
aoqi@0: void* read_section_data(int fd, ELF_EHDR* ehdr, ELF_SHDR* shdr) {
aoqi@0:   void *buf = NULL;
aoqi@0:   if (shdr->sh_type == SHT_NOBITS || shdr->sh_size == 0) {
aoqi@0:      return buf;
aoqi@0:   }
aoqi@0:   if ((buf = calloc(shdr->sh_size, 1)) == NULL) {
aoqi@0:      print_debug("can't allocate memory for reading section data\n");
aoqi@0:      return NULL;
aoqi@0:   }
aoqi@0:   if (pread(fd, buf, shdr->sh_size, shdr->sh_offset) != shdr->sh_size) {
aoqi@0:      free(buf);
aoqi@0:      print_debug("section data read failed\n");
aoqi@0:      return NULL;
aoqi@0:   }
aoqi@0:   return buf;
aoqi@0: }
aoqi@0: 
aoqi@0: uintptr_t find_base_address(int fd, ELF_EHDR* ehdr) {
aoqi@0:   uintptr_t baseaddr = (uintptr_t)-1;
aoqi@0:   int cnt;
aoqi@0:   ELF_PHDR *phbuf, *phdr;
aoqi@0: 
aoqi@0:   // read program header table
aoqi@0:   if ((phbuf = read_program_header_table(fd, ehdr)) == NULL) {
aoqi@0:     goto quit;
aoqi@0:   }
aoqi@0: 
aoqi@0:   // the base address of a shared object is the lowest vaddr of
aoqi@0:   // its loadable segments (PT_LOAD)
aoqi@0:   for (phdr = phbuf, cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) {
aoqi@0:     if (phdr->p_type == PT_LOAD && phdr->p_vaddr < baseaddr) {
aoqi@0:       baseaddr = phdr->p_vaddr;
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0: quit:
aoqi@0:   if (phbuf) free(phbuf);
aoqi@0:   return baseaddr;
aoqi@0: }