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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1995, 2010, Oracle and/or its affiliates. All rights reserved.
*/
/*
* pcom: Print Comment
*
* This program demonstrates the use of the libelf interface to
* read an ELF file. pcom will open an ELF file using
* elf_begin(ELF_C_READ) and examine search the ELF file
* for a .comment section. If a .comment section is found it's
* contents will be displayed on stdout.
*/
#include <stdio.h>
#include <libelf.h>
#include <gelf.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
static const char *CommentStr = ".comment";
static void
print_comment(Elf *elf, const char *file)
{
Elf_Scn *scn = NULL;
GElf_Shdr shdr;
Elf_Data *data;
size_t shstrndx;
(void) printf("%s .comment:\n", file);
if (elf_getshdrstrndx(elf, &shstrndx) == -1) {
(void) fprintf(stderr, "%s: elf_getshdrstrndx() failed: %s\n",
file, elf_errmsg(0));
return;
}
while ((scn = elf_nextscn(elf, scn)) != NULL) {
/*
* Do a string compare to examine each section header
* to see if it is a ".comment" section. If it is then
* this is the section we want to process.
*/
if (gelf_getshdr(scn, &shdr) == NULL) {
(void) fprintf(stderr, "%s: elf_getshdr() failed: %s\n",
file, elf_errmsg(0));
return;
}
if (strcmp(CommentStr, elf_strptr(elf, shstrndx,
shdr.sh_name)) == 0) {
int i;
char *ptr;
/*
* Get the data associated with the .comment
* section.
*/
if ((data = elf_getdata(scn, NULL)) == NULL) {
(void) fprintf(stderr,
"%s: elf_getdata() failed: %s\n",
file, elf_errmsg(0));
return;
}
/*
* Data in a .comment section is a list of 'null'
* terminated strings. The following will print
* one string per line.
*/
for (i = 0, ptr = (char *)data->d_buf;
i < data->d_size; i++)
if (ptr[i]) {
(void) puts(&ptr[i]);
i += strlen(&ptr[i]);
}
(void) putchar('\n');
}
}
}
static void
process_elf(Elf *elf, char *file, int fd, int member)
{
Elf_Cmd cmd;
Elf *_elf;
switch (elf_kind(elf)) {
case ELF_K_ELF:
/*
* This is an ELF file, now attempt to find it's
* .comment section and to display it.
*/
print_comment(elf, file);
break;
case ELF_K_AR:
/*
* Archives contain multiple ELF files, which can each
* in turn be examined with libelf.
*
* The below loop will iterate over each member of the
* archive and recursively call process_elf().
*/
cmd = ELF_C_READ;
while ((_elf = elf_begin(fd, cmd, elf)) != NULL) {
Elf_Arhdr *arhdr;
char buffer[1024];
arhdr = elf_getarhdr(_elf);
/*
* Build up file names based off of
* 'archivename(membername)'.
*/
(void) sprintf(buffer, "%s(%s)", file, arhdr->ar_name);
/*
* Recursively process the ELF members.
*/
process_elf(_elf, buffer, fd, 1);
cmd = elf_next(_elf);
(void) elf_end(_elf);
}
break;
default:
if (!member)
(void) fprintf(stderr,
"%s: unexpected elf_kind(): 0x%x\n",
file, elf_kind(elf));
return;
}
}
int
main(int argc, char **argv)
{
int i;
if (argc < 2) {
(void) printf("usage: %s elf_file ...\n", argv[0]);
return (1);
}
/*
* Initialize the elf library, must be called before elf_begin()
* can be called.
*/
if (elf_version(EV_CURRENT) == EV_NONE) {
(void) fprintf(stderr,
"elf_version() failed: %s\n", elf_errmsg(0));
return (1);
}
for (i = 1; i < argc; i++) {
int fd;
Elf *elf;
char *elf_fname;
elf_fname = argv[i];
if ((fd = open(elf_fname, O_RDONLY)) == -1) {
perror("open");
continue;
}
/*
* Attempt to open an Elf descriptor Read/Write
* for each file.
*/
if ((elf = elf_begin(fd, ELF_C_READ, 0)) == NULL) {
(void) fprintf(stderr, "elf_begin() failed: %s\n",
elf_errmsg(0));
(void) close(fd);
continue;
}
/*
* Process each elf descriptor.
*/
process_elf(elf, elf_fname, fd, 0);
(void) elf_end(elf);
(void) close(fd);
}
return (0);
}
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