jdk8-mips64-public/hotspot: agent/src/os/linux/salibelf.c@a61af66fc99e

     1 /*

     2  * Copyright 2003-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    25 #include "salibelf.h"

    26 #include <stdlib.h>

    27 #include <unistd.h>

    29 extern void print_debug(const char*,...);

    31 // ELF file parsing helpers. Note that we do *not* use libelf here.

    32 int read_elf_header(int fd, ELF_EHDR* ehdr) {

    33    if (pread(fd, ehdr, sizeof (ELF_EHDR), 0) != sizeof (ELF_EHDR) ||

    34             memcmp(&ehdr->e_ident[EI_MAG0], ELFMAG, SELFMAG) != 0 ||

    35             ehdr->e_version != EV_CURRENT) {

    36         return 0;

    37    }

    38    return 1;

    39 }

    41 bool is_elf_file(int fd) {

    42    ELF_EHDR ehdr;

    43    return read_elf_header(fd, &ehdr);

    44 }

    46 // read program header table of an ELF file

    47 ELF_PHDR* read_program_header_table(int fd, ELF_EHDR* hdr) {

    48    ELF_PHDR* phbuf = 0;

    49    // allocate memory for program header table

    50    size_t nbytes = hdr->e_phnum * hdr->e_phentsize;

    52    if ((phbuf = (ELF_PHDR*) malloc(nbytes)) == NULL) {

    53       print_debug("can't allocate memory for reading program header table\n");

    54       return NULL;

    55    }

    57    if (pread(fd, phbuf, nbytes, hdr->e_phoff) != nbytes) {

    58       print_debug("ELF file is truncated! can't read program header table\n");

    59       free(phbuf);

    60       return NULL;

    61    }

    63    return phbuf;

    64 }

    66 // read section header table of an ELF file

    67 ELF_SHDR* read_section_header_table(int fd, ELF_EHDR* hdr) {

    68    ELF_SHDR* shbuf = 0;

    69    // allocate memory for section header table

    70    size_t nbytes = hdr->e_shnum * hdr->e_shentsize;

    72    if ((shbuf = (ELF_SHDR*) malloc(nbytes)) == NULL) {

    73       print_debug("can't allocate memory for reading section header table\n");

    74       return NULL;

    75    }

    77    if (pread(fd, shbuf, nbytes, hdr->e_shoff) != nbytes) {

    78       print_debug("ELF file is truncated! can't read section header table\n");

    79       free(shbuf);

    80       return NULL;

    81    }

    83    return shbuf;

    84 }

    86 // read a particular section's data

    87 void* read_section_data(int fd, ELF_EHDR* ehdr, ELF_SHDR* shdr) {

    88   void *buf = NULL;

    89   if (shdr->sh_type == SHT_NOBITS || shdr->sh_size == 0) {

    90      return buf;

    91   }

    92   if ((buf = calloc(shdr->sh_size, 1)) == NULL) {

    93      print_debug("can't allocate memory for reading section data\n");

    94      return NULL;

    95   }

    96   if (pread(fd, buf, shdr->sh_size, shdr->sh_offset) != shdr->sh_size) {

    97      free(buf);

    98      print_debug("section data read failed\n");

    99      return NULL;

   100   }

   101   return buf;

   102 }

   104 uintptr_t find_base_address(int fd, ELF_EHDR* ehdr) {

   105   uintptr_t baseaddr = (uintptr_t)-1;

   106   int cnt;

   107   ELF_PHDR *phbuf, *phdr;

   109   // read program header table

   110   if ((phbuf = read_program_header_table(fd, ehdr)) == NULL) {

   111     goto quit;

   112   }

   114   // the base address of a shared object is the lowest vaddr of

   115   // its loadable segments (PT_LOAD)

   116   for (phdr = phbuf, cnt = 0; cnt < ehdr->e_phnum; cnt++, phdr++) {

   117     if (phdr->p_type == PT_LOAD && phdr->p_vaddr < baseaddr) {

   118       baseaddr = phdr->p_vaddr;

   119     }

   120   }

   122 quit:

   123   if (phbuf) free(phbuf);

   124   return baseaddr;

   125 }

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