Mercurial > hg > truffle
diff agent/src/os/linux/salibelf.c @ 0:a61af66fc99e jdk7-b24
Initial load
author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
parents | |
children | c18cbe5936b8 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/agent/src/os/linux/salibelf.c Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,125 @@ +/* + * Copyright 2003-2006 Sun Microsystems, Inc. All Rights Reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, + * CA 95054 USA or visit www.sun.com if you need additional information or + * have any questions. + * + */ + +#include "salibelf.h" +#include <stdlib.h> +#include <unistd.h> + +extern void print_debug(const char*,...); + +// ELF file parsing helpers. Note that we do *not* use libelf here. +int read_elf_header(int fd, ELF_EHDR* ehdr) { + if (pread(fd, ehdr, sizeof (ELF_EHDR), 0) != sizeof (ELF_EHDR) || + memcmp(&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 || + ehdr->e_version != EV_CURRENT) { + return 0; + } + return 1; +} + +bool is_elf_file(int fd) { + ELF_EHDR ehdr; + return read_elf_header(fd, &ehdr); +} + +// read program header table of an ELF file +ELF_PHDR* read_program_header_table(int fd, ELF_EHDR* hdr) { + ELF_PHDR* phbuf = 0; + // allocate memory for program header table + size_t nbytes = hdr->e_phnum * hdr->e_phentsize; + + if ((phbuf = (ELF_PHDR*) malloc(nbytes)) == NULL) { + print_debug("can't allocate memory for reading program header table\n"); + return NULL; + } + + if (pread(fd, phbuf, nbytes, hdr->e_phoff) != nbytes) { + print_debug("ELF file is truncated! can't read program header table\n"); + free(phbuf); + return NULL; + } + + return phbuf; +} + +// read section header table of an ELF file +ELF_SHDR* read_section_header_table(int fd, ELF_EHDR* hdr) { + ELF_SHDR* shbuf = 0; + // allocate memory for section header table + size_t nbytes = hdr->e_shnum * hdr->e_shentsize; + + if ((shbuf = (ELF_SHDR*) malloc(nbytes)) == NULL) { + print_debug("can't allocate memory for reading section header table\n"); + return NULL; + } + + if (pread(fd, shbuf, nbytes, hdr->e_shoff) != nbytes) { + print_debug("ELF file is truncated! can't read section header table\n"); + free(shbuf); + return NULL; + } + + return shbuf; +} + +// read a particular section's data +void* read_section_data(int fd, ELF_EHDR* ehdr, ELF_SHDR* shdr) { + void *buf = NULL; + if (shdr->sh_type == SHT_NOBITS || shdr->sh_size == 0) { + return buf; + } + if ((buf = calloc(shdr->sh_size, 1)) == NULL) { + print_debug("can't allocate memory for reading section data\n"); + return NULL; + } + if (pread(fd, buf, shdr->sh_size, shdr->sh_offset) != shdr->sh_size) { + free(buf); + print_debug("section data read failed\n"); + return NULL; + } + return buf; +} + +uintptr_t find_base_address(int fd, ELF_EHDR* ehdr) { + uintptr_t baseaddr = (uintptr_t)-1; + int cnt; + ELF_PHDR *phbuf, *phdr; + + // read program header table + if ((phbuf = read_program_header_table(fd, ehdr)) == NULL) { + goto quit; + } + + // the base address of a shared object is the lowest vaddr of + // its loadable segments (PT_LOAD) + for (phdr = phbuf, cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) { + if (phdr->p_type == PT_LOAD && phdr->p_vaddr < baseaddr) { + baseaddr = phdr->p_vaddr; + } + } + +quit: + if (phbuf) free(phbuf); + return baseaddr; +}