usr/src/cmd/boot/symdef/symdef.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <stdio.h>
  30 #include <string.h>
  31 #include <sys/types.h>
  32 #include <sys/stat.h>
  33 #include <fcntl.h>
  34 #include <unistd.h>
  35 #include <libelf.h>
  36 #include <gelf.h>
  37 #include <errno.h>
  38
  39 /*
  40  * symdef is a very simplified version of nm.  It is used by upgrade and
  41  * create_ramdisk in situations where we can't guarantee that nm will be around.
  42  *
  43  * Two arguments are expected: a binary and a symbol name.  If the symbol is
  44  * found in the name table of the binary, 0 is returned.  If it is not found,
  45  * 1 is returned.  If an error occurs, a message is printed to stderr and -1
  46  * is returned.
  47  */
  48
  49
  50 static void
  51 usage(void)
  52 {
  53         (void) fprintf(stderr, "USAGE: symdef file_name symbol\n");
  54 }
  55
  56 int
  57 main(int argc, char *argv[])
  58 {
  59         int     fd = 0;
  60         int     rv = 1;
  61         uint_t  cnt, symcnt;
  62         Elf     *elfp = NULL;
  63         Elf_Scn *scn = NULL;
  64         size_t  shstrndx;
  65         GElf_Ehdr       ehdr;
  66         GElf_Shdr       shdr;
  67         GElf_Sym        sym;
  68         Elf32_Word      shndx;
  69         Elf_Data        *symdata, *shndxdata;
  70
  71         if (argc != 3) {
  72                 usage();
  73                 return (-1);
  74         }
  75
  76         fd = open(argv[1], O_RDONLY);
  77         if (fd == -1) {
  78                 (void) fprintf(stderr, "%s\n", strerror(errno));
  79                 rv = -1;
  80                 goto done;
  81         }
  82         if (elf_version(EV_CURRENT) == EV_NONE) {
  83                 (void) fprintf(stderr, "Elf library version out of date\n");
  84                 rv = -1;
  85                 goto done;
  86         }
  87         elfp = elf_begin(fd, ELF_C_READ, NULL);
  88         if ((elfp == NULL) || (elf_kind(elfp) != ELF_K_ELF) ||
  89             ((gelf_getehdr(elfp, &ehdr)) == NULL) ||
  90             (elf_getshstrndx(elfp, &shstrndx) == 0))
  91                 goto done;
  92
  93         while ((scn = elf_nextscn(elfp, scn)) != NULL) {
  94                 if ((gelf_getshdr(scn, &shdr) == NULL) ||
  95                     ((shdr.sh_type != SHT_SYMTAB) &&
  96                     (shdr.sh_type != SHT_DYNSYM)) ||
  97                     ((symdata = elf_getdata(scn, NULL)) == NULL))
  98                         continue;
  99                 symcnt = shdr.sh_size / shdr.sh_entsize;
 100                 shndxdata = NULL;
 101                 for (cnt = 0; cnt < symcnt; cnt++) {
 102                         if ((gelf_getsymshndx(symdata, shndxdata, cnt,
 103                             &sym, &shndx) != NULL) &&
 104                             (strcmp(argv[2], elf_strptr(elfp, shdr.sh_link,
 105                             sym.st_name)) == 0)) {
 106                                 rv = 0;
 107                                 goto done;
 108                         }
 109                 }
 110         }
 111 done:
 112         if (elfp)
 113                 (void) elf_end(elfp);
 114         if (fd != -1)
 115                 (void) close(fd);
 116         return (rv);
 117 }